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View Full Version : Necessity is the mother of Invention



lane
11-03-2007, 09:22 PM
At work last week I needed to cut some .175 wide radius groves in some parts I was making for a customer.Had a quick idea for a tool I have had in my mine for years but never got around to building. So I set in and made a crude one and got the job done. It worked so well Friday evening I decided to set in and make a whole set for my lathes at home.Here are some measurements For any one interested.5/8 x1 x4 1/2 CRS Mill face end 7 ,move back leaving .010 from edge of part at 7 to edge of hole . Drill and ream what ever size hole you need. I made 3/16- 1/4 -5/16 -3/8 -and 7/16 . Lay part on side moving back behind reamed hole enough that threads will clear hole and drill and tap 1/4 - 20 thread thru part and counter drill .265 dia. 5/16 deep with bolt head on right side or tail stock side of tool holder.Stand part up and 1/2 inch behind taped hole are about 1 inch from beveled face drill a 5/32 hole thru part on center of 5/8 dem. and thru the 1inch thickness. Then lay parts down on 5/8 side and with a 1/16 slitting saw saw to 5/32 hole. Stand the parts back up in vise and cut .250 deep back about 3/4 from 7 bevel face back. Turn up side down and cut shank of holders to 5/8 thick 3 1/4 long.
Here are some photos .
http://i178.photobucket.com/albums/w277/lane5263/002Frontview.jpg
This is the 5 tool holders.
http://i178.photobucket.com/albums/w277/lane5263/007Toolholdersandtestpart.jpg
Side view
http://i178.photobucket.com/albums/w277/lane5263/003Frontviewwithtestpiece.jpg
Front view with test part
http://i178.photobucket.com/albums/w277/lane5263/MachiningRadius.jpg
Machining grove in test part.
The tool bits are a 3/8 shank broke end mill ,3/16 broke end mill, a 7/16 broke center drill a 5/16 broke center drill and a 1/4 broke carbide drill. So any broke bits will work for bits what ever size you have . Need to make one 1/2 inch but will have to use 3/4 x1 inch stock for that one .

Nutter
11-03-2007, 09:45 PM
Great idea. Thanks for sharing.

jimmstruk
11-03-2007, 09:51 PM
Very good , thanks for the idea. JIM

wierdscience
11-03-2007, 11:16 PM
Good idea,now I have one more tool to make:D

C - ROSS
11-03-2007, 11:31 PM
Darn it anyway now I have more work to do and no time to get it done.

Wasted the afternoon doing honeydo projects and then backed a pickup into the tractor that she left out in the middle of nowhere, several miles on any side of it and I hit the darn thing. Spent the evening straighting the bumper.

Neighbor gave me three 6 volt generators, wanted to put one on a tractor but no time. Special church day tomorrow (100th year anniversary) so tomorrow is gone also.

Nice project wish that I had thought of that way.

Thanks for sharing with us.

Ross

dp
11-03-2007, 11:48 PM
I'll have to whipp one up and try it on my shaper - it has good geometry for a shaper and replaceable cutters. Nice idea. They can be modified to be form cutters for making involute gear cutters, too.

A.K. Boomer
11-03-2007, 11:49 PM
Very Clever Lane, nice workmanship too.

Mcgyver
11-04-2007, 12:14 AM
yours look prettier than mine :D

http://bbs.homeshopmachinist.net/showthread.php?t=24051&page=2&highlight=radius

each one is for a different size? I made one and turned the drill rod down. As i look at yours again, the different sizes would give the smaller dia's more support

Rustybolt
11-04-2007, 09:47 AM
I knew i was saving those broken endmills and taps for a reason. Brilliant idea.

ammcoman2
11-04-2007, 10:00 AM
A really good idea and superb workmanship - as usual. Thanks for sharing.

Interestingly, I have a Diamond tool holder which is used for most work and noticed recently on the Oz website that an option is to install a round tool bit for corner radiusing.

Your aproach is much easier to make and one could angle the tool holder to do corners.

Hmmm - my list has just got longer! As well, it will take me at least three time longer to make them than you did.

Thanks and regards,

Geoff

Lew Hartswick
11-04-2007, 10:41 AM
Lane, How did you grind the cutter ? If it is straight it'll have negative
rake (the 7deg slope) so it has to be at least that or preferably more.
The if it's ground before mounting how to index it with the body of the
tool??
I've built several of the "diamond" tool holders including one for
threading (using a triangular bit) and they work fine. So this using a
round bit for "form tooling" would be a good addition.
Thanks.
...lew...

Fasttrack
11-04-2007, 12:13 PM
Dern it - i was going to post a thread here in a few weeks when i got around to making something like that. I've always got a bunch of broken 1/4" drill bits for some reason so i thought i should make a tool holder to accept broken 1/4" drill shanks.

Those are pretty cool - i think while i still have access to a bridgeport i should make a couple of the common sizes like 1/4 5/16 and 3/8

Tin Falcon
11-04-2007, 01:12 PM
Lane: Great work ,thanks for sharing . You project has been in the back of my mind on the tools to make list.
They are esentally an adaptation of the Smith and Coventry design out of England a hundred or so years ago they also made left and right hand angled versions they were sold as somwhat of a universal tool holder and could be used for turning shaping and planeing. The angled version has the slot cut from the back side rather than the front. The slot and hole for tool tool are oriented 45 degrees from the center of the shank. the beauty of that is you use the same tool for facing cuts and turning cuts.
Thanks again for taking time to write up and photograph the project.
FYI here is a copy of the catalog page.
http://i78.photobucket.com/albums/j108/Tin_Falcon/005.jpg
Tin

John Stevenson
11-04-2007, 07:36 PM
Lane,
Nice work and a credit.
I went into the workshop earlier to find one I did some years ago but couldn't find it.

Probably a good job as compared to yours it was crude but it worked for me at the time.

I had need of a 5/32 radius in a shaft so being lazy / in a rush / etc I dimpled a piece of 3/8" square steel bar with a 5/16" drill and brazed a 5/16" ball bearing into the dimple. Then ground the top half away so I had half a sphere.
A bit of dressing of the holder on the grindstone and it was away to go.


.

lane
11-04-2007, 08:08 PM
Lane, How did you grind the cutter ? If it is straight it'll have negative
rake (the 7deg slope) so it has to be at least that or preferably more.
The if it's ground before mounting how to index it with the body of the
tool??
I've built several of the "diamond" tool holders including one for
threading (using a triangular bit) and they work fine. So this using a
round bit for "form tooling" would be a good addition.
Thanks.

...lew...

Just grind with bench grinder with table set at eye ball10-12 degrees. If you get a soothe grind you can eye ball the grind marks on the face to rotate tool square to the shank plenty close enough.

lazlo
11-04-2007, 09:47 PM
What's the advantage of the tangential ("diamond") holders?
I see them a lot in the turn of the century machine shop books, but I've never seen a modern one?

I vaguely recall an advert in one of the 90's HSM magazines...

dp
11-04-2007, 10:08 PM
The "Gadget Builder" has an example here: http://www.gadgetbuilder.com/ToolHolders.html#Tangent

And Frank Ford has a couple quickie alternates:
http://www.frets.com/FRETSPages/Machining/QuickTricks/ToolPostFile/toolpostfile.html

Spin Doctor
11-05-2007, 11:36 AM
What's the advantage of the tangential ("diamond") holders?
I see them a lot in the turn of the century machine shop books, but I've never seen a modern one?

In a production tooling situation the amount of regrinds in the tool is one heck of a lot more

lazlo
11-05-2007, 11:58 AM
In a production tooling situation the amount of regrinds in the tool is one heck of a lot more

I read GagetBuilder's history of the Diamond/Tangential tool, and his build log of making a Quick-Change version of the side-tangential tool. He seems really happy with his, and says that he was getting a better finish with it, but he seems to imply that it was because it was easier to grind to a nice finish than a "conventional" turning tool.

GagetBuilder: any comments? :)

Bill in Ky
11-05-2007, 01:43 PM
Thanks for posting that. Great pictures too...
Now I have a new project !!

BadDog
11-05-2007, 02:11 PM
I think it's only real advantage, other than easy sharpening, is that it would (or could, depending on mount) be some tiny more rigid than a standard oriented bit. Other than that, you're just giving up flexibility in form for ease of sharpening. A reasonable trade-off I would think. Use it where it works well, and switch to conventional when you need some other form. But I can't see where it's all that much different otherwise. I've thought of making one for my AX post, but it never got to the top of the pile.

Hmmm, maybe some combination of round/diamond holder? ;)

lazlo
11-05-2007, 02:20 PM
Hmmm, maybe some combination of round/diamond holder? ;)

I was actually referring generically to Lane's toolholders as tangential toolholders, or diamond toolholders as they're sometimes called in the old machine shop texts.

The tool itself can be round, or corner-tangential (diamond tool), or side tangential (like GagetBuilder's tool), but it seems like the approach angle (and benefits) are the same for all three.

BadDog
11-05-2007, 02:25 PM
Agreed.

That last sentence was in reference to the previous "I wanted to build one" comment. I had always planned on a simple diamond, but it would be nice if it could also do various round (whew, complicated).

Jim Caudill
11-05-2007, 03:01 PM
Lane, nice work and an inspiration! One question, did you mean to allow .100" between the front rake and the bit holder hole? I interpet your posting to indicate only .010" wall thickness at the front edge of the toolholder (which seems a little on the thin side - might as well cut the slot all the way thru)

Frank Ford
11-05-2007, 03:21 PM
I have little trick for when I need a quick radius cut. I just grind the end of a carbide drill bit or end mill so it has a sharp corner at the perimeter, and clamp it in a standard #2 holder:

http://www.frets.com/FRETSPages/Machining/QuickTricks/ToolPostFile/carbidedrillend03.jpg
(Only the two front screws are tight because this is still a good drill so I wouldn't want to crack off a cutting edge.)

I can adjust the depth of cut by raising or lowering the holder as I run the tool into the work - here I'm running in reverse:

http://www.frets.com/FRETSPages/Machining/QuickTricks/ToolPostFile/carbidedrillend04.jpg

Files work too, if you're into breaking a few rules:

http://www.frets.com/FRETSPages/Machining/QuickTricks/ToolPostFile/toolpostfile03.jpg

Cheers,

Frank Ford
FRETS.COM (http://www.frets.com)
Gryphon Stringed Instruments (http://www.gryphonstrings.com)
My Home Shop Pages (http://www.frets.com/FRETSPages/Machining/index.html)

Spin Doctor
11-05-2007, 04:37 PM
I read GagetBuilder's history of the Diamond/Tangential tool, and his build log of making a Quick-Change version of the side-tangential tool. He seems really happy with his, and says that he was getting a better finish with it, but he seems to imply that it was because it was easier to grind to a nice finish than a "conventional" turning tool.

GagetBuilder: any comments? :) Almost any form tool that would be ground for production purposes in the last 100 years would most likely be ground on a Tool Grinder of some sort. Reginding the tool would simply be a matter of setting up in a jig or fixture and dusting it off. Plus in a production setting
the tool would probably have a height adjustment screw that it would sit on in the tool holder

lane
11-05-2007, 08:10 PM
Lane, nice work and an inspiration! One question, did you mean to allow .100" between the front rake and the bit holder hole? I interpet your posting to indicate only .010" wall thickness at the front edge of the toolholder (which seems a little on the thin side - might as well cut the slot all the way thru)

Yes .010 the only reason is you want the hole as close to the edge as possible when drilling and reaming it . Then after you cut the clamp slot. and finish the holder you may mill or grind a little more off the front and expose some of the radius of the tool bit. Getting some of the body in front out of the way for more working clearance.

Tin Falcon
11-06-2007, 04:57 AM
What's the advantage of the tangential ("diamond") holders?
I see them a lot in the turn of the century machine shop books, but I've never seen a modern one?

I vaguely recall an advert in one of the 90's HSM magazines...
If you read the turn of the centery books you will see that most tooling of the time was hand forged from carbon steel and ground . If you look at the tool Add I posted it gives a cost savings break down of useing a tangental tool vs forging and grinding ones. Bottom line it saves time it is much easier to grind a quck touch up by the operator as aposed to sending a tool back to the tool room to be dressed up and ground. also you do not have to keep reforging new ones. just replace the blank when one wears down . Also using a blank of HSS as aposed to a carbon steel cutting edge the tool lasts longer between sharpening.
Ease of grinding is a big advantage. I can grind by hand any shape thay is needed but it took time to learn and it takes time to do. Also any time you can just do a quick touch up to the top of the tool this insurse you did not change the tools shape while grinding.
Another advantage is you can do turning and faceing cuts with the same tool another time saver.
The modern indexable carbide insert tool holders have pretty much taken over the tool crib in modern shops . The reason much higher production speeds repeatability and you are paying the machinst to machine not grind tools.
Tin

GadgetBuilder
11-20-2007, 12:52 PM
I read GagetBuilder's history of the Diamond/Tangential tool, and his build log of making a Quick-Change version of the side-tangential tool. He seems really happy with his, and says that he was getting a better finish with it, but he seems to imply that it was because it was easier to grind to a nice finish than a "conventional" turning tool.

GagetBuilder: any comments? :)


Hi Lazlo,

I missed this thread when it was new so didn't comment then.

I like the tangential a LOT and use it in preference to other tools whenever possible. I recently added a second lathe and need another tangential because it is a pain to keep resetting the height when moving the tangential between the machines.

I think the reason the tangential works so well is that the rake is steeper than that of most tools (unless one takes pains to add a chip breaker to increase the rake). Another thing is that when cutting from left to right it has a slicing action rather than cutting with the point and this provides an even better finish than right to left cutting. Unlike regular QCTP holders, the tangential can turn or face without changing the position on the toolpost.

Sharpening is quick and easy using the dedicated sharpening holder so the tool is kept sharp, perhaps another reason it works so well. Because the sharpening fixture reproduces the angle exactly, relatively little material is removed when sharpening so it takes only seconds - most of the time is taking the tool in and out of the holder. The hollow grind in the cutting face makes lapping after sharpening quick too.

One problem with the tool is caused by the steep rake - it sometimes chatters if I try to cut brass and also some aluminum. I suspect that grinding a cutter with less rake (by packing the sharpening fixture up at the front) would work better for these materials but haven't tried it yet.

John

Norman Atkinson
10-29-2008, 04:26 AM
Apart from an attempt to point DickeyBird in a direction to find cheap and cheerful turning tools- and I should have said HemingwayKits, I sort of kept out.
Lane has come up with the old pre-last century tangential or skiving tools. To my shame, I have yet to try them.

However, the time is ripe to say 'What if?' What if one has to have a concave ground tool and not a convex one?
Unlikely? Think again! I have just ground a concave parting tool for my rear tool post on a Myford. Why? Quite simply the tool is inverted and the subsequent ribbon off the kerf is narrowed to minimise binding in the cut. It literally rolls the ribbon into nice little 'Curlie Queues'.

Now this is only one time for a different grind and so what about doing the ends of end mills which should take a very slight radius to avoid chipping? Again, a proper t&C is desirable. The next situation is on how to go the whole hog and regrind ball nosed cutters.

I can think of even more wicked things but enough for now.
Well, how do the rest of you manage?

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

With failing eye sight, I suspect that I have misposted but really the subjects are so close that they should really be linked.

oldtiffie
10-29-2008, 07:18 AM
Another option is at (my) post #18 at:
http://bbs.homeshopmachinist.net/showpost.php?p=390253&postcount=18

Thomas Staubo
10-29-2008, 05:05 PM
I have just ground a concave parting tool for my rear tool post on a Myford. Why? Quite simply the tool is inverted and the subsequent ribbon off the kerf is narrowed to minimise binding in the cut. It literally rolls the ribbon into nice little 'Curlie Queues'.

How do you grind such a concave parting tool, or rather how is the tool ground?

Is it concave on the front edge of the blade, or on the top (bottom in your case with the inverted placement)?


A picture could be helpful if a description is effortful.


.

Norman Atkinson
10-29-2008, 08:40 PM
Hi Thomas,
I suspect that you have a Myford and will have read George Thomas's Model Engineers Workshop Manual.
GHT describes the construction of a rear tool post which is inverted and goes on to suggest that the blades be inclined at 7degrees which allows the top( or bottom) of the blade to be straight. In other words, it only needs bringing forward to centre height after re grinds.
GHT also remarked that the front edge could take a convex vee to assist parting off. This is where I was at. It worked OK. He went on to suggest that if a vee of 140 degrees( concave) was ground along the (top) edge, the swarf would narrow and being upside down fall out of the cut and not jam. When all Hell would be let loose0 the Big Bang!

Ok, he suggested that a decent T&C would make easy work of the grinding. Then friend Chaddock was sort of unearthed( recent correspondence) and he had this spindle which would operate at angle grinder speeds( Oh, yes!) He could use a conventional thin angle grinder wheel which was cheap and nasty to be messed about with. He could afford to waste discs rounding them off etc.
I got round to angle grinding wheels on the Clarkson and thought- bugger it, the thin 6mm wheel is already rounded off. So I simply left it rounded and put the blade in a small( Myford) vice and ran the 1" long grind.
Martin Cleeve had done something similar but used a drill but with a rounded wheel edge.
So I have a blade more or less GHT, done on a Chaddock idea with a Cleeve approach.

It took less time to do than write it!

No photos, I am pretty useless at such modern stuff

Cheers

Norman