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davidwdyer
01-07-2010, 05:50 PM
I'm studying Ivan Law's idea for home made gear cutters. He has a setup using buttons. Those who have the book will know what I am talking about.

What I don't understand is on pages 114 and 115.

There he has charts for sizes of "buttons" and their distances from each other.
The number are labeled as "Ins" which seems to be inches. BUT, that makes no sense to me. :confused:

Could it be, for example, that on page 114 cutter no. 1, the distance between the buttons is 49.60 inches? That would take some humongous lathe.:eek:

Any help with these charts would be appreciated. Could the measurements be in millimeters?

dp
01-07-2010, 06:05 PM
If the buttons for cutter #1 are .513" in diameter then there's no way you're going to get their centers closer than .513". Either there's an error in the text or it doesn't say what I think it says.

loose nut
01-07-2010, 06:28 PM
The numbers shown can't be Inches or MM, look at the W if it was 4" it is way to wide and 4mm is way to narrow. I made some gear cutters many years ago according to this book and all I can remember is that this section gave me fits to. The button size for making a form tool for cutting a 20 gear, I can't remember the DP, was about 3/8".

I think the info in the charts has to be put into an equation to get your answers but its been to long and I don't remember how I did it.

The answer may be in an earlier section of the book.

davidwdyer
01-07-2010, 06:29 PM
If the buttons for cutter #1 are .513" in diameter then there's no way you're going to get their centers closer than .513". Either there's an error in the text or it doesn't say what I think it says.

That's what confusing me. Perhaps there is some numbering system common to the Brits that I don't understand.

Hey you guys over on the other side of the pond, how about a little help here.

loose nut
01-07-2010, 06:34 PM
Ivan Law was old school and the book was written before Britain fell completely into the Metric madness, other diam. in the book appears to be in inches.

loose nut
01-07-2010, 07:03 PM
Might be all wrong here but I think this is it, maybe, possibly.

I looked in my gear catalog and there isn't a 1 DP gear in it. Conclusion, it is just a base line for calculating out the proper answer.

Reread page 114 top right side wear it says that the charts are for 1 DP and to divide the value in the chart by the DP of the gear you wish to cut.

take a 20 dp gear with 24 teeth

this would be a #5 cutter

for d divide 8.55 by 20 = .4275
c divide 9.4 by 20 = .47
e divide 3.71 by 20 = .1855

and the width of the tool divide 4 by 20 for the practical minimum. =0.200" (not real sure about this, seems to narrow)

Give it a try and see if it works out.

Pherdie
01-07-2010, 07:18 PM
It appears there may have been an error. Taken from www.rittercnc.com:

> I've been reading Ivan Law's book on making gear cutters and he
> described the design and build of a "button cutter" to generate an
> approimation of the involute profile.
>
> Mr. Law sets out two tables of design information for the cutters, one
> 20deg pressure angle and the other is at 30deg pressure angle. The
> design data is normalised at one diametrical pitch.
>
> The puzzle I have is that the two buttons are of diameter "D" and the
> distance between the button centres is "C".
>
> The thing I'm struggling with is that in both tables "C" is less than
> "D". How can this be?
>
> Too be honest it's a bit of an armchair question as I've had a kind
> offer from one of the guys on the group to cut the two gears I'm after,
> but can't abide leaving things I don't understand to one side!
>
> Steve
>
>
I have a spreadsheet that will calculate these values. You can see it here:

http://www.helicron.net/files/involutecuttercalcs.xls

It calculates the button diameter, pitch and infeed for the form tool
described by Ivan Law in his book "Gears and Gear Cutting". To obtain
actual sizes then either divide by the DP of the actual gear to get
sizes in inches or multiply by the module to get sizes in millimeters.

The table in the book is acknowledged as being in error and other tables
exist on the 'net. One of these can be found here:
http://www.metalwebnews.com/howto/gear/gear1.html
(written by John Stevenson)

dp
01-07-2010, 07:22 PM
I see that it has been normalized to 1 in the text. I missed that. That still leaves the 135T diameter buttons needing a shave for any DP, though, to get them close enough together on center.

I recall now this same mental exercise a couple years ago when I got the book. One more gray cell accounted for!

Edit: I'm also curious about the use of the topping cutter - I know what it does but don't yet know what it does looks like when it's done.

loose nut
01-07-2010, 09:43 PM
There seems to be a significant difference between Ivan Law and the charts at metal web news which makes it strange that when I cut some gears using the charts in Ivan's book they run very nicely and quiet, with the lathe change gears that they ran against.

Since bought cutters cover a range of sizes, it is taken that a fair amount of error in the cutter will still produce a good gear so the difference between Ivans book and the MWN article doesn't seem to be that big a deal.

Which ever charts you use the method is still the same.

loose nut
01-07-2010, 09:47 PM
It appears there may have been an error. Taken from www.rittercnc.com:

> The puzzle I have is that the two buttons are of diameter "D" and the
> distance between the button centres is "C".
>
> The thing I'm struggling with is that in both tables "C" is less than
> "D". How can this be?
>
>

This is true of the tables but if you do the math for the buttons "c" becomes greater then"d".

Someone else can figure it out I'm not a mathematician.

Rich Carlstedt
01-07-2010, 10:15 PM
Guys I may be all wet so this is a shot in the dark.
Could it be that flats need to be ground on the buttons so the C/L can be made closer.
If you have .5 buttons, and need a .480 C/L, then a .010 flat should be made
on each button before mating.
The cutter you generate doesn't go to the button C/L as I recall ?
(Read Ivans work 40 years ago)

Rich

oldtiffie
01-08-2010, 12:07 AM
Here is the OP:

I'm studying Ivan Law's idea for home made gear cutters. He has a setup using buttons. Those who have the book will know what I am talking about.

What I don't understand is on pages 114 and 115.

There he has charts for sizes of "buttons" and their distances from each other.
The number are labeled as "Ins" which seems to be inches. BUT, that makes no sense to me. :confused:

Could it be, for example, that on page 114 cutter no. 1, the distance between the buttons is 49.60 inches? That would take some humongous lathe.:eek:

Any help with these charts would be appreciated. Could the measurements be in millimeters?

My copy of Ivan Law's book says it was first published in 1988.

It can be reasonably be assumed that his methods etc. were developed and refined previous to that and pretty well certainly before affordable CAD was available or in use.

The tables referred to are indeed for 1 DP at various pressure angles. As the book says - divide by the DP you want to use.

The units are in inch and could just as well be in mm.

While "DP" is an "inch" measure/unit and the metric (mm) system is in "module" they have a defined relationship so it is relatively easy to convert to or from one to the other. In short, convert your metric "Module" to the inch "DP" and there you are.

If you have a good grip of CAD there is no good reason why you could not use the underlying principles used in Law's book and to solve for your own disc diameter and separation (centre distance).

I'd prefer to use a single disc and use a dial indicator for the "off-set" (centre distance) to set the single disc to cut both radii. That can all be solved in CAD.

Dual discs require a lot of accuracy for the separation as well as having a common centre line normal to the axis of the cross-slide.

These discs are harder (worse??) than screw-cutting as while both are "form-tool" work, the cutting of the gear cutter has very long cutting edges as well as being an interrupted cut - the worst of all worlds. There is no "off-set the top slide by 29.5 degrees" either.

I would not worry too much (or at all) about the "In feed "E"" in Law's book either as I'd rather use Machinery's Handbook - or preferably any CAD - and a good set of vernier calipers (gear micrometer or disk micrometer - if you have them) to measure "over the gears" to get the correct tooth thickness and "clearance" and "back-lash". In this case the "distance over the gear teeth is theoretically the distance over the disks which cut the gear-cutter.

I should point out that in many if not all cases that we - or I anyway - see in BBS posts and on u-Tube videos are small gears on long (cantilevered) arbors and cutting brass, aluminium or mild steel.

Vibration and "chatter" are "killers" for all of these tools - "shop-bought" included - as they all have zero back and side rake - which is not bad for cast-iron and brass (which handle these "zeroes" pretty well) but it is quite another story for most steels. This applies even to HSS gear cutters and so applies more so to those made from "01" (USA) or "Silver Steel" (UK, OZ, NZ).

For this reason I prefer to use a single toothed HSS hand-ground cutter with top and side rake and just cut one side of the gear tooth at a time.

I prefer to "gash" the cut and remove the bulk of the material to be removed with a saw and then use my "single sided" single-toothed tool to cut one side to about completion and then reverse the tool in the tool-holder and reverse the direction of the mill spindle and direction of feed.

If I need to re-sharpen the hand-ground tool, I can do it with a diamond hand hone (round) "on the job" or take it out and sharpen it on the pedestal grinder.

I can always "take a little bit more" off with that very keen edge better than I can with a multi-toothed cutter - especially one with no back or side rake.

When - or if - I ever get around to buying a "shop-bought" HSS cutter, I will hand grind the back and side rake on it as I use the "as new" edge as a guide for grinding.

Restoring the original edge is not a problem on the Tool & Cutter grinder as I can set the side and top rakes to zero and take very little off and so get more "(s)mileage" from my cutter.

This post by John Stevenson is a very elegant solution to the "sticking-out arbor as a cantilever" problem and very effectively simulating/emulating the better support on a horizontal mill:
http://bbs.homeshopmachinist.net/showpost.php?p=505770&postcount=10

which is:

Make one and make a support while you are at it to keep it rigid.

http://www.stevenson-engineers.co.uk/files/vertical%20support.jpg

Not my machine and I'd like to give credit on this to whoever made it but I don't have that information.

If I was making one I'd use a dovetail packing piece and an off the shelf self aligning plummer block.

.

davidwdyer
01-08-2010, 04:00 AM
I see that it has been normalized to 1 in the text. I missed that. That still leaves the 135T diameter buttons needing a shave for any DP, though, to get them close enough together on center.

I recall now this same mental exercise a couple years ago when I got the book. One more gray cell accounted for!

Edit: I'm also curious about the use of the topping cutter - I know what it does but don't yet know what it does looks like when it's done.

The buttons don't cut anything on the actual "face" of the disc you are cutting. They only cut on the sides. So to do any adjusting or cutting on the very end, the flat edge of the cutter, you have to have some kind of "toping" tool.

John Stevenson
01-08-2010, 04:16 AM
Rich has one of the answers, you need flats on the sides of the buttons so you can get the required centre distance.

The tables are based on 1DP so you divide all the numbers by the DP you are using.

There are differences in Ivan's table to the ones on the Metal Web forum BUT if you lookcarefully at the drawings there is a difference in how they are used.

Usings Ivans you touch off on the OD with the OD of the button, move sideways to line up central, then infeed. In Ivans although he gives a width W it's only a recomendation

The Metal Web tables with W is critical because you touch on both edges with the buttons to ensure you are central THEN infeed.

This is why the tables are different in values but if you draw them out for a given size in CAD and overlay them they are a perfect match.

So in a nutshell it doesn't matter who's tables you use but you MUST use the infeed method linked to those tables.

.

oldtiffie
01-08-2010, 05:29 AM
Thanks John.

On re-reading my previous post I goofed as ther "interrupted cut" only applied to the almost Heath-Robinson (but very clever) reciprocating arrangement on a lathe that I think you've posted several times. Could you re-post or provide a link to it please.

I think it fair and best that the pages of Ivan's book referred to be posted so that those who don't have the book or access to it are not excluded from the discussion. Here they are:
http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Gear_form4.jpg

This is how gears mesh in a true involute - note that the involute curve runs from the gear blank outside diameter to the base circle (the "clearance" at the bottom of the cut is not shown):
http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Involute_wheel1.gif

This is my solution to Ivan Laws' disks and tables. It too can can be drawnfor 1DP and re-scaled to suit any other DP - including metric modular (which are fractional - ie "decimal") - DP's.

The "half tooth" etc. can be "mirrored" around the centre line and both as a unit can be spaced/arrayed around any Pitch Circle Diameter (PCD) as often as required for the number of teeth.

The solution for the disks is:
http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Gear_form6.jpg

It relies - as does Laws - for the arc swung from the tangent point on the base circle and intersecting the pitch circle an angle which is equal to the Pressure Angle (PA) from the base circle to the gear blank OD very closely approximating the involute curve.

You can have any DP, PA or numbers of teeth that you like with this.

If you draw your gear out in full you can not only get the measurement over the gears (for gear tooth thickness and "clearance" and "back-lash") but can use it to generate a *.DXF file for use in CNC-ing the gear.

If you CNC it, you can side-step the "buttons" process altogether.

A caution though.

This should be OK for gears that are not critical and which require to conform exactly to the involute form. It should suffice for the majority of smaller - and some larger - gears made in the average HSM shop.

Having said that, the "standard" sets of gears for each DP don't follow the involute form precisely either as that have a correct involute curve at the pitch circle and with the rest of the gear form being of a cycloid form.

I suggest further reading of Machinery's Handbook and other books/texts which cover these topics in a lot more detail.

There is no reason why a single tooth end-milling cutter with the tooth form on it should not be used directly in the milling-head collet and the gear-cutting arbor and "discs" etc. done away with altogether. Both John Stevenson and Evan have done it this way and it seemed to work very well.

Perhaps John and Evan will re-post the articles or provide links to the previouys relevent threads as they are well worth seening (again).

davidwdyer
01-08-2010, 05:34 AM
Yes, I get it now.

I wasn't seeing that you need to divide these number by the DP.

Also, I see that OldTiffe talks about chatter. I have already had problems with this with cutters with wide faces. Any other thoughts or tips. I see that the "one button" solution lessens this. How about you John? Are you using two buttons or one?

loose nut
01-08-2010, 10:37 AM
More points to ponder.

1. Ivan law wrote his book mostly for amateurs who build models, not for pro's and business who have to "get it right". It is intended as a "close is good enough" situation, as a replacement for expensive cutters. It isn't necessary to over think this, if you follow his directions and use his tables you can produce usable gears. 'nuf said.

2. if you are using a lighter lathe stick to the single sided cutter, trying to take a cut with the double sided cutter is asking for chatter and loud screeching noises, and your lathe won't like it either.

3. It has been stated that the diam. on the charts (for 1 DP) are large. The radius for low DP gears would be vary large so these techniques are intended more for a higher DP gear (20 DP for example) and not a 5 DP gear.

4.Tiffie stated that DP is for imperial gears and the Module system is for Metric gears. This is the way that works best, it would be harder to use the DP system with MM and modules with Imp. but there isn't any reason that you can't. Both module and DP can be used with either Imp. or Metric measurement, if necessary, just not advised.

John Stevenson
01-08-2010, 11:06 AM
More points to ponder.

3. It has been stated that the diam. on the charts (for 1 DP) are large. The radius for low DP gears would be vary large so these techniques are intended more for a higher DP gear (20 DP for example) and not a 5 DP gear.

The procedure for gear calculations is scaleable, 20 DP information is 1/2 of 10 DP so it makes sense to do the tables calculated on 1 and scale from this.

It doesn't mean that you have to use this method to make cutters for 1DP.

.

loose nut
01-08-2010, 12:21 PM
I agree, I think that making cutters for say 5DP gears might be a bit impractical (not necessarily impossible) with this method considering the size of the buttons it would need.

5DP 20 tooth gear D=1.56" C=1.74"
5DP 80 tooth gear D=6.43" C=6.32" (Figures worked out according to Ivan Laws charts in book, may be in error???)

My point was that he wrote this book for "Model Engineers" making small gears not for companies making large gears.

How many of us on this site are going to cut 5DP gears in our home shops, this method is perfectly good for what the OP wants.

davidwdyer
01-08-2010, 03:31 PM
More points to ponder.

1. Ivan law wrote his book mostly for amateurs who build models, not for pro's and business who have to "get it right". It is intended as a "close is good enough" situation, as a replacement for expensive cutters. It isn't necessary to over think this, if you follow his directions and use his tables you can produce usable gears. 'nuf said.

2. if you are using a lighter lathe stick to the single sided cutter, trying to take a cut with the double sided cutter is asking for chatter and loud screeching noises, and your lathe won't like it either.

3. It has been stated that the diam. on the charts (for 1 DP) are large. The radius for low DP gears would be vary large so these techniques are intended more for a higher DP gear (20 DP for example) and not a 5 DP gear.

4.Tiffie stated that DP is for imperial gears and the Module system is for Metric gears. This is the way that works best, it would be harder to use the DP system with MM and modules with Imp. but there isn't any reason that you can't. Both module and DP can be used with either Imp. or Metric measurement, if necessary, just not advised.

I already have problems with screeching and chatter doing various other jobs. My biggest lathe is a 13" South Bend which is quite light. Sometimes I wish I had a 2 ton Monarch.

I am right now at the point of making this decision about one button or two. Looks like one is the right choice.

Has anyone considered cutting the drill rod at a slight angle, thereby making an oval? This would seem to come even closer to an involute curve.

dp
01-08-2010, 04:58 PM
Has anyone considered cutting the drill rod at a slight angle, thereby making an oval? This would seem to come even closer to an involute curve.

They are already at a 5 degree angle in the original design.

oldtiffie
01-08-2010, 10:27 PM
More points to ponder.

1. Ivan law wrote his book mostly for amateurs who build models, not for pro's and business who have to "get it right". It is intended as a "close is good enough" situation, as a replacement for expensive cutters. It isn't necessary to over think this, if you follow his directions and use his tables you can produce usable gears. 'nuf said.

2. if you are using a lighter lathe stick to the single sided cutter, trying to take a cut with the double sided cutter is asking for chatter and loud screeching noises, and your lathe won't like it either.

3. It has been stated that the diam. on the charts (for 1 DP) are large. The radius for low DP gears would be vary large so these techniques are intended more for a higher DP gear (20 DP for example) and not a 5 DP gear.

4.Tiffie stated that DP is for imperial gears and the Module system is for Metric gears. This is the way that works best, it would be harder to use the DP system with MM and modules with Imp. but there isn't any reason that you can't. Both module and DP can be used with either Imp. or Metric measurement, if necessary, just not advised.

Thanks loose-nut.

I will try and address some of your queries as they probably being asked by some others a well.

I agree with your paras 1 and 2.

Your para 3 is very good as it points out the practical limitations of Laws and similar methods.

Laws method of making and setting disks - all of which have their separate errors and tolerances - is a tool to make a tool (the cutter) which is intended to cut the gear which at best is an approximation of a true involute.

The cutter still has to be hardened and tempered and a honed or ground edge achieved with 01/Silver-steel disks and th cutter they make which is to cut the gear.

These cutters at best are subject to the same limitations as the "shop-bought" HSS cutter "sets" (for each range in each DP and PA) in that only one gar cut with each.any cutter is reasonably accurate with rest of the range increasingly inaccurate all-be-it at a generally satisfactory level.
(See Machinery's Handbook for details).

This para of yours needs a bit of comment too:

4.Tiffie stated that DP is for imperial gears and the Module system is for Metric gears. This is the way that works best, it would be harder to use the DP system with MM and modules with Imp. but there isn't any reason that you can't. Both module and DP can be used with either Imp. or Metric measurement, if necessary, just not advised.

That pretty well sums it up.

Use in either the DP or Module type of gear or converting from one to the other or working in partial instead of "full number" DP's or modules is a bit daunting without conversion tables.

As Laws says, the text is about a DP of 1 and that it can be scaled to suit any (other) DP. He does not say that all DP's must be whole/full numbers at all. There is no reason for a gear to have a "full number" pitch circle diameter either. They can be "decimal" or "fractional" numbers.

The form of the gear is the same irrespective of whether it is a "DP" or a "module" gear.

That infers that when a "full number DP" gear is converted to a "module" gear the the gear will have a partial/fractional module pitch circle diameter and DP. The reverse applies in converting a module gear to a DP gear.

All that is required for gears to mesh satisfactorily is that they be at the correct centre distance and have the same circular pitch, pressure angle and tooth form.

Here are a some tables that may assist:
http://i200.photobucket.com/albums/aa294/oldtiffie/Black_book/BB_50-51.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Black_book/BB_52.jpg

precisionmetal
01-09-2010, 03:37 AM
One very minor mod to the chart above:

The WD of 2.25/DP applies to 20DP and coarser, and ((2.2/DP) + .002") is typically what's used when finer than 20DP.

Gears are generally quite straightforward. What can get whacky is splines -- there are so many different "standards" (how can they be standards if there are many???) that reverse engineering a spline can become difficult at times.

As oldtiffie eludes to though -- there are many combinations of diametral pitch and pressure angle that yield the same base pitch, and base pitch is really what defines the gear.

PM

oldtiffie
01-09-2010, 05:38 AM
Thanks PM.

My reasons for pursuing this as I have are mainly to de-mystify
"gearing" and its principles. It was also to try making it easy and available to many HSM-ers who may not otherwise try and give it a go. This might encourage them make some small gears that will work by using the machines and the tools that they have at their disposal.

It is far short of rocket science for day-to-day use for light loads.

I have tried to provide the option of developing the profiles in a CAD system where they can pick off dimensions as well as for those that might want to proceed further to CNC.

It is quite possible to mark the whole gear out with a good scriber, rule and pair of machinists/fitters dividers.

Even marking out a single tooth - or just one side/flank can be adequate if marked out and filed accurately to make a profile to hand-grind and hone a "tooth" on the scrap end on a HSS end mill and to use it in the mill as an end mill.

I see too little here about making basic gears and use of quite basic fundamentals.

I see far too much pseudo "higher-level" discussion on gear hobbing, generating, shaving, shaping, grinding, lapping etc. which does or may or is intended to over-awe and discourage some timid or otherwise adventurous newer members from "getting into" "gear-making".

I was more than a bit pi\$\$ed off in the rudeness early in this thread of discussing a book that some did not have. It actually - and perhaps was intended to - exclude those who were not in the club with those who did have it - hence my posting a copy of it.

A caution for those new to or newly informed about basic spur gearing - this is pretty simple thus far but the going gets a lot heavier from here on in.

The more so as the topic moves past spur gears.

Anyway, I hope it was of help to some.

davidwdyer
01-09-2010, 06:37 AM
Oldtiffe,

I have copied and printed the charts you included here. This is still something I have not dominated yet. So I will need to ask more questions later as the project evolves.

There was no intent to offend anyone by referring to the Law's book. I merely had a specific question about said pages.

Your suggestion about marking out the teeth or a tooth is excellent. I will try it. Unfortunately, will be away from the shop for about six weeks and will not have a chance to follow through immediately.

They say (whoever "they" are) that learning new things in old age helps the mind keep active and avoid alzheimers. No doubt this hobby and the many things a person can learn can be part of this. What a great excuse to go out and buy more tooling!

"They" also say that those who learn a new language at an older age, for example, have 80% less chance of this disease.

loose nut
01-09-2010, 01:06 PM
To add onto to Tiffies notes.

If someone wants some good basic info on gears of all types, fitting them up not on how to cut them, get a good catalog.

I have a Boston Gear cat. from 20 years ago and each gear type has an engineering section that gives the info on how to use the gears in question mounting, spacing, HP that can be handles etc. nothing to hard, basic math for engineering.

Ivan Laws book is one of the Model Engineer Workshop Series of books that where Published by Argus press (MAP before them) I don't know who sells them now but these books are good information for beginners. They stick to the basics and cut out the crap and where made for people with limited and/or dubious equipment at best.

Tiffie, I don't think anyone was trying to be rude. In my own case I was just trying to put across the case for following the instructions in the book, keep it simple and the OP would probably have success

Lodsb
01-09-2010, 01:20 PM
Is anyone interested in this sort of thing? It calculates the buttons, etc, for a given tooth count, as opposed to a range. Nothing to prevent it being used for a range, however. Answer a few questions and it prints the various dimensions. It is a Perl script (http://www.activestate.com/activeperl/). Free stuff.

Criticisms appreciated. :-)

The output:

Number of teeth in gear: 78
Pressure Angle: 14.5
Diametral Pitch: 14

78 Tooth gear information
O.D. of gear blank= 5.71428571428571
Pitch Diameter of gear: 5.57142857142857
Thickness of cutter blank: 0.250153307955296
Button diameter: 1.39497430830332
Infeed (crossfeed): 0.605493174810102
Longitudinal (compound) feed: 0.0836451830942603
(Dual buttons, center to center = 1.43783725007009)
Depth Of Cut: 0.154071428571429

------------------------- cut here -------------------------------------------
#!/usr/bin/perl -w
#
\$input->ornaments(0);

\$Pi = 4 * atan2(1,1);
\$Teeth = \$input->readline("Number of teeth in gear: ");
print "\n";

\$OD=(\$Teeth+2)/\$DP; # od of gear
\$PD=\$Teeth/\$DP; # pd of gear

# 20 degree PA full depth teeth
\$Dedendum = 1.250/\$DP;
\$Depth = 2.250/\$DP;
\$Clearance = .250/\$DP;

# Fine pitch gears -- 20 DP and up, 20 degree PA only.
if (\$DP > 19) {
\$Depth = 2.2/\$DP + .002;
\$Dedendum = 1.2/\$DP + .002;
\$Clearance = .2/\$DP + .002;
}

# All standard 14.5 DP gears.
if (\$PA == 14.5) {
\$Depth = 2.157/\$DP;
\$Dedendum = 1.157/\$DP;
\$Clearance = .157/\$DP;
}

\$oo=\$ll*(1-sin(\$PA*(\$Pi/180)))+\$Dedendum;# cross slide infeed
\$mm = (\$Pi*\$OD)/\$Teeth;
\$c2c = (\$mm + (\$ll * 2)) - (2 * \$pp);# buttons, center to center

print "\$Teeth Tooth gear information\n";
print" O.D. of gear blank= \$OD\n";
print" Pitch Diameter of gear: \$PD\n";
print" Thickness of cutter blank: ",\$mm + .020,"\n";
print" Button diameter: ",\$ll * 2,"\n";
print" Infeed (crossfeed): \$oo\n";
print" Longitudinal (compound) feed: ",\$pp - .010,"\n";
print" (Dual buttons, center to center = \$c2c)\n";
print" Depth Of Cut: \$Depth\n";
print" Nose radius, each corner: ",.3/\$DP,"\n\n";

------------------------- cut here -------------------------------------

dp
01-09-2010, 01:25 PM
I was more than a bit pi\$\$ed off in the rudeness early in this thread of discussing a book that some did not have. It actually - and perhaps was intended to - exclude those who were not in the club with those who did have it - hence my posting a copy of it.

Tiffie - this is crazy. If everyone got offended because the topic involved some tool or resource they didn't have this would be an unhappy place. I don't have a rotary table, for example, but I devour posts about them because I'm interested. I bought the Law book because it was (pardon the pun) geared to people like me, interesting, and affordable. I learned of it here. Rather than being offended by posts regarding its content I became interested in it and bought it. The very same process applied to my owning a fake Blake coaxial indicator.

Hopefully we never get to the point where our posts have to consider the libraries of our fellow members. That is taking PC way too far.

dp
01-09-2010, 01:38 PM
Is anyone interested in this sort of thing? It calculates the buttons, etc, for a given tooth count, as opposed to a range. Nothing to prevent it being used for a range, however. Answer a few questions and it prints the various dimensions. It is a Perl script (http://www.activestate.com/activeperl/). Free stuff.

Criticisms appreciated. :-)

Round off is ok - especially on my little Asian lathe :)

bash-3.2\$ perl buttons.pl
Number of teeth in gear: 48
Pressure Angle: 20
Diametral Pitch: 16

48 Tooth gear information
O.D. of gear blank= 3.125
Pitch Diameter of gear: 3
Thickness of cutter blank: 0.224530771718085
Button diameter: 1.02606042997701
Infeed (crossfeed): 0.415688547327737
Longitudinal (compound) feed: 0.0834395077235986
(Dual buttons, center to center = 1.04371218624789)
Depth Of Cut: 0.140625

Lodsb
01-09-2010, 02:20 PM
Thanks for testing it! :-) Someone (Mr. Law?) published a chart that seems to have it's range calculated from the middle, rather than the smallest tooth count. I'm also calculating feeds based on edges. I believe John used the corner. Just a couple things to keep in mind if any discrepancies are discovered when comparing notes.

The dedendum might need to be varied if you're trying to match an existing gear. A little work in Qcad (using the info generated by this script) will print the cutter profile to paper, on which the gear can be laid for checking.

'Tis a very slow process, this. A \$30 store bought cutter will turn days of work into hours -- they are about 20 times faster and almost mindless to use.

John Stevenson
01-09-2010, 02:37 PM
Is anyone interested in this sort of thing? It calculates the buttons, etc, for a given tooth count, as opposed to a range. Nothing to prevent it being used for a range, however. Answer a few questions and it prints the various dimensions. It is a Perl script (http://www.activestate.com/activeperl/) (http://www.activestate.com/activeperl/%29). Free stuff.

Criticisms appreciated. :-)

-------------

.

dp
01-09-2010, 02:38 PM

.

The link is for folks who don't have Perl installed. The perl code itself is in the post. Copy/paste into a file on your machine.

(change of subject) Do you know how the topping cutter is used on the Eureka?

oldtiffie
01-09-2010, 03:02 PM
Originally Posted by oldtiffie
I was more than a bit pi\$\$ed off in the rudeness early in this thread of discussing a book that some did not have. It actually - and perhaps was intended to - exclude those who were not in the club with those who did have it - hence my posting a copy of it.

Tiffie - this is crazy. If everyone got offended because the topic involved some tool or resource they didn't have this would be an unhappy place. I don't have a rotary table, for example, but I devour posts about them because I'm interested. I bought the Law book because it was (pardon the pun) geared to people like me, interesting, and affordable. I learned of it here. Rather than being offended by posts regarding its content I became interested in it and bought it. The very same process applied to my owning a fake Blake coaxial indicator.

Hopefully we never get to the point where our posts have to consider the libraries of our fellow members. That is taking PC way too far.

Dennis.

In the general case I would agree with you, but in this specific case I do not.

It only took a bit of consideration, time and effort to copy the pages that I did and then up-load and provide the link to them so that all could see them and either just read or participate in the discussion. Everything was done at my computer other than the 20 metres I had to go to and get off my freckle for and walk to get the book/s and return it when finished.

The discussion topic was about (two) specific pages in a specific book that some of us have.

A lot of my attitude in that regard has its origin in people quoting something or worse, some old "guru" as authority or proof, or in support of what they say and denying anyone else the privilege of checking it out for themselves.

Same goes for selective quoting.

Laws' book covers a topic of interest to some here pretty well for those who may be new to gears and gearing - and perhaps for some who may want or need to review that knowledge.

I would not go to the trouble of copying the whole book but in this instance it was and is my opinion that having the subject matter "on the screen" should have facilitated the discussion.

I do copy and post a lot of stuff mainly as source or an indication of what is available in the context of the discussion or a point I have made or am seeking to make or explore.

This is the OP:

I'm studying Ivan Law's idea for home made gear cutters. He has a setup using buttons. Those who have the book will know what I am talking about.

What I don't understand is on pages 114 and 115.

There he has charts for sizes of "buttons" and their distances from each other.
The number are labeled as "Ins" which seems to be inches. BUT, that makes no sense to me. :confused:

Could it be, for example, that on page 114 cutter no. 1, the distance between the buttons is 49.60 inches? That would take some humongous lathe.:eek:

Any help with these charts would be appreciated. Could the measurements be in millimeters?

It was unfortunate that the OP did not post the pages - for what-ever reason - but as I had a copy of the book anyway I could use my own book - on my own - but the discussion which was specifically requested by the OP was - at that stage - restricted to those who had a copy of the book and went and got it.

I decided to make the pages available to all who may have wanted to read them and/or participate in the discussion.

As easy as that.

John Stevenson
01-09-2010, 03:02 PM
Dennis, done that but what extension do I save as ?

Found a perl application file but it asked for some details then closed.

I'm not into computers as regards all this, everything has to be explained, i's and t's crossed.

Not sure what you mean by a topping cutter on the Eureka, I have never cut gear cutters on one ironically but have made many special form tools.

lazlo
01-09-2010, 03:08 PM
Dennis, done that but what extension do I save as ?

Save it as a .pl file, and the ActivePerl install should have associated itself with that extension. It's basically the same equations in the Excel spreadsheet posted earlier.

Not sure what you mean by a topping cutter on the Eureka, I have never cut gear cutters on one ironically but have made many special form tools.

Dennis, the Eureka is for relieving hobs. John, do you still have that cool video of your Eureka running? I've got it stashed somewhere...

Edit: I found Charles Lessig's video of his Eureka. Charles added the half-nut feed, which is extremely clever IMHO:

dp
01-09-2010, 03:13 PM
Dennis, done that but what extension do I save as ?

There's no standard but common practice is to use .pl which we all recognize as a Perl script.

Found a perl application file but it asked for some details then closed.

Likely what happened is it opened a terminal window, ran the tool, and then slammed the terminal window shut on you. Use the Start -> Run -> cmd menu command to start a terminal window that will stay open. Then go find where the Perl code is and type Perl <filename.pl>.

Not sure what you mean by a topping cutter on the Eureka, I have never cut gear cutters on one ironically but have made many special form tools.

Ok - in the section of the book that Tiffie has provided there is an example button holder and a topping cutter. I'm guessing it is intended to provide the proper profile for the clearance face of the finished cutter. It looks a bit like a parting cutter but fits in the Eureka tool.

oldtiffie
01-09-2010, 03:48 PM
Lazlo.

The discussion on the "Eureka" and related text etc. are at pages 123>134 in Laws' book - too much to copy all of them for a narrow discussion, but I did get off my ar\$e again for the sake of the discussion and "Eureka" - here are pages 128 and 129 which give an indication of the "Eureka":

http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Gear_form7.jpg

http://en.wikipedia.org/wiki/Eureka_(word)

Laws specifically refers to using it for a non-hobbing cutter - just a simple multi-toothed cutter similar to those in "store-bought" gear sets.

Laws - at page 124 - does how-ever say that Eureka tool is limited to cutters with an outside diameter of 1 1/4" >1 1/2" diameter and 20DP.

Frankly, if I were that desperate for a multi-tooth cutter, I'd make/use HSS/01/Silver Steel inserts to go in a multi-tool insert adaptor directly inserted into the MT/R8 taper of the/my milling head.

Again, with a little effort and consideration, anyone who is interested can see the gist of and perhaps participate in this further expansion of the content of Laws' book.

davidwdyer
01-09-2010, 04:02 PM
Oldtiffe,

Frankly, if I were that desperate for a multi-tooth cutter, I'd make/use HSS/01/Silver Steel inserts to go in a multi-tool insert adaptor directly inserted into the MT/R8 taper of the/my milling head.

I'm curious to know just what you mean by this comment. I guess I don't know what a multi-tool insert adapter is.

oldtiffie
01-09-2010, 04:27 PM
Oldtiffe,

Frankly, if I were that desperate for a multi-tooth cutter, I'd make/use HSS/01/Silver Steel inserts to go in a multi-tool insert adaptor directly inserted into the MT/R8 taper of the/my milling head.

I'm curious to know just what you mean by this comment. I guess I don't know what a multi-tool insert adapter is.

David.

Here are examples of th general principles of a face cutter.
http://www.directindustry.com/industrial-manufacturer/face-milling-cutter-76501.html

It is an adaptor into which separate insert/s tool can be mounted.

A good similar example is the cutter heads on a "Stump Muncher" machine to get rid of tree stumps etc.

davidwdyer
01-09-2010, 04:34 PM
Let me see if I get this right. You would replace what normally might be carbide inserts with custom made tool steel gear cutter bits. That's a great idea. Have you or anyone else done it before? That would require making several exactly the same, would it not?

dp
01-09-2010, 04:49 PM
Lazlo.

The discussion on the "Eureka" and related text etc. are at pages 123>134 in Laws' book - too much to copy all of them for a narrow discussion, but I did get off my ar\$e again for the sake of the discussion and "Eureka" - here are pages 128 and 129 which give an indication of the "Eureka":

Try to remember that not everyone has the ability to scan books, or a place on the net to put the pics once scanned. If I didn't own my own servers I'd never post any pics because I don't care for the crap places like photobucket put you through. That said, thanks for the links and images. It is appreciated that you can and do provide them.

dp
01-09-2010, 04:56 PM
Dennis.

In the general case I would agree with you, but in this specific case I do not.

Go back to the title of the thread, as you like to remind us, and you will see that anyone thin skinned enough to get pissy about not having the book and images handy has no grounds for it. The very thread itself requires one to have the book at hand or to sit quietly and watch those of us who do chat about it.

There's also limitations to what "fair use" means when scanning in copyrighted work - if you copy the entirety of a topic such that you've removed the need to purchase the book in order to fabricate what it describes, it probably will set you up to contact a barrister to defend yourself.

You'd be better off hooking up with a bareista for a latte':
http://www.mynorthwest.com/index.php?nid=221&sid=57118

John Stevenson
01-09-2010, 05:02 PM
Robert,
I may still have that video but it's poor quality.
Now I have this very expensive top end camera mount [ 1/4" whit bolt in a magnetic clock holder ] I will do another video at a lower speed so the action is a bit clearer, may be next week when the heating is on in the shop.

.

oldtiffie
01-09-2010, 05:29 PM
Let me see if I get this right. You would replace what normally might be carbide inserts with custom made tool steel gear cutter bits. That's a great idea. Have you or anyone else done it before? That would require making several exactly the same, would it not?

David,

making and using inserts was common shop practice that has largely been replaced with pre-shaped indexable inserts which (re)locate accurately.

The same principles apply as on the stump grinder in that there are basically two methods.

1. Sharpen the insert-able cutters individually and then re-set/mount them individually - which requires some considerable skills - to have each and all of them aligned/set up to the adaptor (mill spindle axis) and each other.

2. Leave the inserts in the adaptor and re-sharpen them in situ and in sequence - just as a chain-saw blade is re-sharpened on a jig or special tool. It is quite feasible to adapt a good but cheap chain-saw sharpening grinder to be an effective tool and cutter grinder for jobs such as this - especially if used with an indexable tool-holder such as a common shop "Spindexer".

oldtiffie
01-09-2010, 05:56 PM
Originally Posted by oldtiffie
Dennis.

In the general case I would agree with you, but in this specific case I do not.

Go back to the title of the thread, as you like to remind us, and you will see that anyone thin skinned enough to get pissy about not having the book and images handy has no grounds for it. The very thread itself requires one to have the book at hand or to sit quietly and watch those of us who do chat about it.

There's also limitations to what "fair use" means when scanning in copyrighted work - if you copy the entirety of a topic such that you've removed the need to purchase the book in order to fabricate what it describes, it probably will set you up to contact a barrister to defend yourself.

You'd be better off hooking up with a bareista for a latte':
http://www.mynorthwest.com/index.php?nid=221&sid=57118

If the "informed" discussion were to be limited to the privileged few - and there-by excluding the "uninformed' (the "great unwashed"??) you might as well have conducted it by PM.

My days of "hooking" (up?) with "hookers" are perhaps sadly - but as happens - fortunately - long gone. Some were café' - as you might expect.

I have had occasion to be aware of young "ladies" - of the "oldest profession" - and (as some might say) of "questionable morals" - soliciting operating out of shop-fronts. Does that make her/them "Shop-front Lawyers" or "Solicitors" who can "(de?) brief" a Barrister for me?

oldtiffie
01-09-2010, 06:04 PM
Originally Posted by oldtiffie
Lazlo.

The discussion on the "Eureka" and related text etc. are at pages 123>134 in Laws' book - too much to copy all of them for a narrow discussion, but I did get off my ar\$e again for the sake of the discussion and "Eureka" - here are pages 128 and 129 which give an indication of the "Eureka":

Try to remember that not everyone has the ability to scan books, or a place on the net to put the pics once scanned. If I didn't own my own servers I'd never post any pics because I don't care for the crap places like photobucket put you through. That said, thanks for the links and images. It is appreciated that you can and do provide them.

Dennis.

It would cost nothing for anyone intereted to ask - nor for anyone else to have at least make the offer.

I just pre-empted the need for that so I am in no position to kmnow if others may have made the offer - or not.

I have no problems with Photo-bucket as any minor inconvenience is more than off-set by the convenience of my having it available as I need it.

dp
01-09-2010, 06:10 PM
If the "informed" discussion were to be limited to the privileged few - and there-by excluding the "uninformed' (the "great unwashed"??) you might as well have conducted it by PM.

The topic was driven by need - the OP needed help with something from the Law book and that requires access to the Law book contents in order to participate. That is not equivalent to setting up an insider's discussion group.

It happens a lot here that people have a need for help with some odd bit - like the back-out dial for threading on a Monarch lathe. I don't have one so can't help, but I was sufficiently fascinated by the concept that I grabbed images for later reference of one that was torn down for repair.

I assure you that when I start work on my version of the Eureka I'm going to probably ask questions about it here or elsewhere and anyone who grumbles that I've posted a topic for which they have no documentation will be ignored :)

dp
01-09-2010, 06:14 PM
I have no problems with Photo-bucket as any minor inconvenience is more than off-set by the convenience of my having it available as I need it.

There are a lot of broken Photobucket image links on this BBS. The best place to see an example is in the sticky post at the top of this page (Posting pictures with photobucket). It's annoying to follow a topic only to see the images have been yanked from PB for what ever reason.

John Stevenson
01-09-2010, 06:26 PM
Dennis,

My copy of the Eureka was built from Ivan drawings but everything was scaled up X 2.

Mine was built to make form cutters for the piano industry, ironically it's never made a gear cutter.
Because I was paid to make this I had it all case hardened after building it and we had a section in maintenance that made cupboards, benches and wooden jigs.
One very skilled woodworker and I had him to make a custom felt lined box for this to fit it.

A piano factory has plenty of nice wood and felt :D

oldtiffie
01-09-2010, 06:28 PM
That's true Dennis.

The usual cause and reason is that those who up-loaded them saw fit to remove them from or to move them to another folder in PB or canceled their account - or had it canceled - or who had exceeded the limit that PB allocates to "free" as opposed to "paid (for)" accounts.

None of that - so far as I can see - is the fault of PB.

dp
01-09-2010, 06:44 PM
That's true Dennis.

The usual cause and reason is that those who up-loaded them saw fit to remove them from or to move them to another folder in PB or canceled their account - or had it canceled - or who had exceeded the limit that PB allocates to "free" as opposed to "paid (for)" accounts.

None of that - so far as I can see - is the fault of PB.

Yep - understood. I'm not condemning PB - just the problems associated with sites like PB.

lazlo
01-09-2010, 07:15 PM
Lazlo.

The discussion on the "Eureka" and related text etc. are at pages 123>134 in Laws' book

Laws specifically refers to using it for a non-hobbing cutter - just a simple multi-toothed cutter similar to those in "store-bought" gear sets.

My bad -- in that video I posted, Charles Lessig is actually backing-off (form relieving) a hob, not an involute cutter. He added that functionality to the Eureka.

I just looked at page 124 again, and you're right -- Ivan has a non moving single-tooth version of the Eureka to form relieve multi-toothed involute cutters.
It's copied from Balzar's Form Relieving tool, a good writeup here:

http://www.csparks.com/VanDervoort/index.xhtml

But the topping tool on the bottom-left of Figure 101 is the cutter used to cut the form relief. In other words, its the same cutting tool that Charles is using in his video.

You obviously don't need to form relieve the teeth if you make the involute flycutter as he shows on page 122.

oldtiffie
01-09-2010, 07:28 PM
Thanks Lazlo.

I will scan the pages later.

But in the interim - and as slightly OT but not entirely unrelated - the "disc" ("relieved" cutter) in another guise is an excellent method of "form-tooling" - which includes but is not limited to - gear cutters, screw-cutter etc.

I will go over the methods later.

lazlo
01-09-2010, 09:53 PM
But in the interim - and as slightly OT but not entirely unrelated - the "disc" ("relieved" cutter) in another guise is an excellent method of "form-tooling" - which includes but is not limited to - gear cutters, screw-cutter etc.

Ivan's disc-based involute cutter (that you turn with the buttons we've been discussing) is turned eccentrically on the shaft, so you don't need to form relieve it. You obviously could turn it concentric and then back-off the disc, but I thought the eccentric shaft was very clever/elegant.

oldtiffie
01-10-2010, 12:10 AM
Lazlo.

The fixture that the cutter is cut on (???) DOES off-set the gear cutter but the cutter profile is concentric with its (the disk) centre ( Fig 97 page 121).

The cutter "top face" is cut to be 1/8" below the cutter centre-line so that when the cutter edge (with zero/"radial" top/back rake) is raised to the centre line there will be some degree of front clearance.

The ones I've used and/or made are cut a bit deeper so the the cutting edge can be rotated (to give some top/back rake) and raised to centre to give some front clearance. That back rake makes a huge difference as regards cutting as it "shears" instead of "bashing" its way through - similar to a good tap. Just imagine using a tap with zero back rake (OK on brass and cast-iron though!!).

The beauty of the cutters is that you can have two alternative cutting faces/edges and they can be hand-ground (pedestal grinder - no jigs etc. needed) off the top face - no need to worry about the front faces at all - and as the cutter is on a locating spindle in the adaptor/tool-holder in the tool-post there is no need to worry about re-alignment. Just tighten up and away you go.

In theory there is a "compound angle problem" but practically, providing not more than 5 degrees is involved it shouldn't matter - over five degrees -narrow/decrease the point angles by 1 degree (ie on a 60 degree screwing tool narrow the included angle to 59 degrees.)

But realistically it is be left "as is".

As I've gone as far as I have and also as I've opened my bloody big mouth and berated others for not posting the pics of the pages under discussion - here goes:

http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Gear_form8.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Gear_form9.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Gear_form10.jpg

lazlo
01-10-2010, 11:07 AM
The fixture that the cutter is cut on (???) DOES off-set the gear cutter but the cutter profile is concentric with its (the disk) centre ( Fig 97 page 121).

The cutter "top face" is cut to be 1/8" below the cutter centre-line so that when the cutter edge (with zero/"radial" top/back rake) is raised to the centre line there will be some degree of front clearance.

You're talking about the flycutter :) I'm talking about the disc-based cutter, which is figure 100 --- the top-right picture on page 123 (the last picture in your post). That's turn eccentrically so you don't have to form relieve it.

oldtiffie
01-10-2010, 09:26 PM
Originally Posted by oldtiffie
The fixture that the cutter is cut on (???) DOES off-set the gear cutter but the cutter profile is concentric with its (the disk) centre ( Fig 97 page 121).

The cutter "top face" is cut to be 1/8" below the cutter centre-line so that when the cutter edge (with zero/"radial" top/back rake) is raised to the centre line there will be some degree of front clearance.

You're talking about the flycutter :) I'm talking about the disc-based cutter, which is figure 100 --- the top-right picture on page 123 (the last picture in your post). That's turn eccentrically so you don't have to form relieve it.

http://i200.photobucket.com/albums/aa294/oldtiffie/Gear_theory/Gear_form10.jpg

Thanks Lazlo - really.

Oops - twice.

I missed your post and I got it wrong ("foot in mouth" disease).

You are quite right.

I went back to the methods we used to make those types of cutters for screw-cutting, form-tooling etc.

The tools used to make those discs were set at lathe centre height and had a good back rake and front clearance on them but the tool profile was "adjusted" (compound angles) to be correct on the disc tool when it was at centre height so that it had both back rake and front clearance. The entire profile was abole to be used just by grinding the top face ona pedestal grinder. I think that John Stevenson posted a pic of one.

There were no available "big iron" or "main-frame" computers - let alone PC's or cheap portable hand-held scientific calculators that we have now. It was all done from standard "Logarithms and Other Tables" - and with slide rules and pen and paper. Total PITA.

Compound angles without the use of a good 3-D/"modeling" CAD package is very difficult.

But if it works its very good - and if it doesn't? - "back to square one".

Here are stages 1 and 2 of a relatively simple example of one I did some time ago for a simple screwing tool or the like. I think it was for solving a cutting edge profile using a square HSS tool-bit in a "tangential tool-holder" situation if I recall correctly.

http://i200.photobucket.com/albums/aa294/oldtiffie/Sketches/Tangent-diamond_tool1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Sketches/Tangent-diamond_tool2.jpg

I could do it by "Solid Geometry" in a good CAD package that had 3-D using all of "Model Space" to achieve the required result in "Paper Space" but even though I am quite well acquainted with the use and principles of CAD (used it quite a while ago) I am too far out of "hands on" practice to have to re-learn it.

But I have to get back "up to speed" with my CAD - but not yet.

dp
01-10-2010, 11:56 PM
I could do it by "Solid Geometry" in a good CAD package that had 3-D using all of "Model Space" to achieve the required result in "Paper Space" but even though I am quite well acquainted with the use and principles of CAD (used it quite a while ago) I am too far out of "hands on" practice to have to re-learn it.

But I have to get back "up to speed" with my CAD - but not yet.

I like your hand drawings and that you have gone to the additional effort to color them. This image was from a discussion of tangential threading cutters and how to get to 60º using compound angles and a square section cutter.

Would love to webpub a full workup of that discussion, including the hand drawn art and working tools photos if you're willing, on my server.

oldtiffie
01-11-2010, 01:10 AM
Originally Posted by oldtiffie
I could do it by "Solid Geometry" in a good CAD package that had 3-D using all of "Model Space" to achieve the required result in "Paper Space" but even though I am quite well acquainted with the use and principles of CAD (used it quite a while ago) I am too far out of "hands on" practice to have to re-learn it.
But I have to get back "up to speed" with my CAD - but not yet.

I like your hand drawings and that you have gone to the additional effort to color them. This image was from a discussion of tangential threading cutters and how to get to 60º using compound angles and a square section cutter.

Would love to webpub a full workup of that discussion, including the hand drawn art and working tools photos if you're willing, on my server.

Thanks for the huge compliment Dennis.

Go for it - with my blessing.

I put it up as being on the web anyway - not just on the VP HSM forum.

I'd prefer that my name not be associated with it if you can (I am painfully shy, modest, inoffensive and introverted as you will have noticed!!) - but if that can't be managed - go ahead anyway - as the end gain is more important than my mis-guided vanity (or something).

If it helps you to help others, I am more than pleased to assist in any way I can - in any HSM-related items of interest that I post.

I am a trained and qualified Draftsman - but I prefer to sketch and colour. I don't really care about the "Technical Correctness" of my work - as long as the "message" is there and useful in the hands of the reader/user I am satisfied and have met my objective.

In my chequered career (Drafting - but not Chess included) - I used to teach the Chief Engine Room Artificer - and 0fficer pre-University level - candidates. (I am an ex Chief Ordnance Artificer). I concentrated on "back of a writing pad" size page as we had to in "on the job" situations in the Navy where brevity and accuracy and using what we had to hand was used extensively. My attitude - and those in the classes - was that a concise sketch that "worked" was preferable to a "nice drawing" that didn't. They were great guys and very good thinkers, innovators and lateral thinkers but the Submariners among them really were a "stand-out".

We convinced the "Management" to use "sketch" instead of "draw" and that when we set a realistic problem the class was broken up into small groups (3>4) and told to find a job in our various Marine Engineering facilities that we had (lots). They were able to go back to the Chief's Mess (I was a member too) and the Lounge or Bar or their accommodation and sort out the pros and cons. If there were say 5 or more submissions of project sketches and every one was different from the others but if each had a viable solution then each was correct. Each group had to distribute copies to every other group and each had to explain their approach and reasons - "in writing" and verbally and answer queries, comments and criticism from the others. The classes assessed and gave the "pass mark/level" (we never had anyone fail the course - even if some came close). The course was for very capable "hands on" guys where "on the job" counted most and got them to where they were. It was not for the "academics". The "math" and science stuff (lots) were taken by other but the Navy really was superb in the "after hours" tutoring and assistance they gave in those areas - and some needed a lot.

I was asked if I'd give teaching "Buoyancy and Stability" a go to fill in gaps if the Engineer/Shipwright Officer was not available. I only had to do it a couple of times but I loved it and was assessed as making a pretty good fist of it. It took a lot of study not only to "teach" it but to answer and discuss some very interesting comments, advice and scenarios. Needless to say some B & S appreciation was pretty important and of interest to all of us on a war-ship at sea.

It was a great time with some great people - and some very "interesting" "after hours" "activities".

But the basis of it was good sketching.

A whole 24 top-quality drafting stations (manual) got junked - but the air-conditioning stayed. That big class-room was VERY popular with a lot of others!!

Management (Marine Engineering Officers) were very supportive as they could see the benefit to the Fleet and careers of the candidates.

"On the job sketching 101" was essential when I was an apprentice and it has stood me in good stead in many ways over many years since.

I hope it is of help to others.