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outlawspeeder
11-16-2012, 12:17 PM
I want to build a QCTP. That said Iíve been looking at many of the plans out there. I want two mounts. The top will tighten the mount, lower to lock the quick mounts. There is a wedge type, pin type, and pin with flats on it.

So on to my questions:
What is the best way to lock the quick mount? Wedge type, Pin type, or Pin with flats on it. (If there are others Ö Please post.
If you know of a good set of plans to start from please post. I still have not seen how the wedge style works so one of those plans would be great!

I know I can buy one of these but then this would not be a hobby.

danlb
11-16-2012, 12:27 PM
The wedge type is generally considered superior because it allows you to remove a tool and pot it back on more precisely than a piston style. This is because the wedge pushes the holder into the edge of the dovetail. A piston style holder pushes the holder out , so the location is based on beveled edges of the dovetails.

In general, a cheap QCTP will get you within a few thousandths of an inch when you put the tool back on.


I used a piston style on my smaller lathe and have no problems with it, but I always check the alignment of everything when I change tools.


Dan

Bob Fisher
11-16-2012, 05:15 PM
I have one of each and have not noticed much difference in performance when changing tools. The smaller one is a Dorian and on my 9X20, the AXA size is on my 40's vintage Logan. Both seem ok to me. I once had a Harbor Freight QCTP which worked also worked fairly well. The HF unit is really simple and is basically a "wedge" type. Bob.

outlawspeeder
11-16-2012, 05:36 PM
Ok so here the next big question??? AXA size Is ther A double D? What are the sizes? The size of the dove tail hight range of the tool rest???

Maybe I'll build the taper jig first. I think I have the plan for that.

Duffy
11-16-2012, 08:20 PM
I have a "cheap and dirty" piston type, but am in the process of building a "split dovetail" type. This will follow the design sold as a casting kit by Andy Lofquist at Metal Lathe Accessories. His design uses a different size tool block from the "standard" designs, and i want to have ALL my tool blocks interchageable betwee both lathes.
essentially, his design uses only one locking handle. It first locates the tool on the compound, and then, with more torque, locks the assembly. This is achieved by forcing a tapered, (self-releasing,) plug downwards to cause the sides of the dovetail to spread and lock the tool holder. The clearance between dovetail and tool holder is only a few thou, so a slight turn on the handle locks pretty securely.
I am building from scratch and the only bit that matters is the taperd plug, which is recommended to be cast iron.
This design appeared in one of either HSM or MW waaaay back.
Building your own tool blocks is a mugs game. It is generally agreed on this site that you cant buy the raw material for the price of a finished tool block, ($8.00-$10.00!)

danlb
11-16-2012, 08:45 PM
Ok so here the next big question??? AXA size Is ther A double D? What are the sizes? The size of the dove tail hight range of the tool rest???

Maybe I'll build the taper jig first. I think I have the plan for that.

The size that matters for the tool holders is the height of the cutting edge above the top of the compound. Look at the following link for the dimensions.
http://www.industrydepot.com/DorianToolToolHolders.htm

Consider the following for a small 9 inch lathe; Assume there is 7 inches swing over the saddle, but the compound has a raised spot for the tool post. The distance from the top of the compound to the center of the chuck is only 1.5 inches. That means that the total height of the tool and the 'A' dimension of the tool holder must be less than 1.5 inches when added together.

Dan

Paul Alciatore
11-17-2012, 02:38 AM
If you are going to make one, you may want to consider an alternative design. This is mine and it has some advantages over the standard dovetail design.

http://img.photobucket.com/albums/v55/EPAIII/QConSBLathe.jpg

One advantage is it's basically a two piece construction: the post and the holder. This makes it rock solid because when the holder is attached to the post there is 360 degree contact between them making it virtually a single, solid piece of steel. Far more solid than the limited contact provided by a dovetail design.

The flat on the post serves as an indexing reference. It is a lot broader than some round post designs that use a slot and pin for indexing. This provides very good repeatability when the holders are interchanged. I have measured better than 0.001".

Another advantage is you can change holders with one hand in a single motion. Just grab the holder by the handle of the adjustable nut and drop it on the post. A quick rotation of that handle and you are done. No tools needed. You don't even have to shift your hand from the holder to the locking lever. Removal is equally easy and fast.

Adjustments of the tool position are easy and they do not interact with each other. A tool can be repositioned in the holder without changing the angle or height. Height changes do not change angle or position. Etc. This makes adjustments in use very easy.

The dimensions can be scaled to fit almost any lathe.

Of course, it does not use the commercially available, dovetail style holders.

This photo shows the various parts.

http://img.photobucket.com/albums/v55/EPAIII/Disassembled.jpg

Ignore the SS SHCS shown for locking the tool bits down. I replaced them with grade 8 SHCS shortly after the photo was taken due to flattening of the tips under pressure.

The construction was published in the Feb-Mar 2010 issue of Machinist Workshop. Or if you PM me I can e-mail you a copy.

jackary
11-17-2012, 07:26 AM
Hi outlawspeeder I have just built a variation of the MLA toolholder and I am pleased with the outcome. I does not index because I do not do much repetition work, it locks both the toolblock and at the dovetail with just a slight tightening of the central handle. I have fitted it to a new topslide (compound) for my Chipmaster lathe. The plan was to minimise the cantilevered overhang of the toolholder.
http://i107.photobucket.com/albums/m287/jackary2003/P1030617.jpg
http://i107.photobucket.com/albums/m287/jackary2003/P1030612.jpg


Alan

outback
11-17-2012, 09:32 AM
Below is a quick change AXA post I made. The toolholders are locked in place with a 1/4-20 SHCS. I used it for 5 or 6 years then bought a Aloris toolpost. It is simple and easy to make.

http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/CAD%20Drawings/DOVETAIL.jpg

http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/CAD%20Drawings/TOOLPOST.jpg

http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/CAD%20Drawings/ASSEM1-1.jpg

http://img.photobucket.com/albums/v30/jglass/quickchange.jpg

Here it is again on my Denford/Orac CNC lathe. I came up with a speed handle for tightening the toolholders.
with handle (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/highspeedspindleinlathe.jpg)

Jim

rode2rouen
11-17-2012, 12:07 PM
I want to build a QCTP. That said I’ve been looking at many of the plans out there. I want two mounts. The top will tighten the mount, lower to lock the quick mounts. There is a wedge type, pin type, and pin with flats on it.

So on to my questions:
What is the best way to lock the quick mount? Wedge type, Pin type, or Pin with flats on it. (If there are others … Please post.
If you know of a good set of plans to start from please post. I still have not seen how the wedge style works so one of those plans would be great!

I know I can buy one of these but then this would not be a hobby.


The Omni Post type would be a good starting point for "rolling your own". Stone ax simple, rugged design that could be easily scaled to the size of your particular lathe.

http://krfcompany.com/


Rex

outlawspeeder
11-17-2012, 11:27 PM
Outback I like that one. I would like to put a handle on it to make it Quick. Jackary, that is a very clean look. Paul Alciatore I like the it but there is not a up/down adj.

I am still looking but have started to pull from the best of what I see.

Paul Alciatore
11-18-2012, 12:56 AM
My post DOES have an "up/down" adjust (tool height). It is a bit hard to see in the photos because the screw is recessed. If you look at the tool holder that is standing on edge in the rear of the second photo, you can see the adjustment screw sticking out of the bottom, next to the "D" shaped hole for the post.

It is easily adjustable from the top and since it uses friction (fishing line in the threads) to hold the adjustment there is no locking nut and no backlash when adjusting it. Simply dial it in and re-lock the holder on the post. Fast, easy, and accurate. Far easier than the height adjustment on the "standard" dovetail holders which can change in height when the adjustment is locked down.

All in all, I did put a lot of thought into the design and I believe it is better than most that I have seen.



Outback I like that one. I would like to put a handle on it to make it Quick. Jackary, that is a very clean look. Paul Alciatore I like the it but there is not a up/down adj.

I am still looking but have started to pull from the best of what I see.

justanengineer
11-18-2012, 01:51 AM
One advantage is it's basically a two piece construction: the post and the holder. This makes it rock solid because when the holder is attached to the post there is 360 degree contact between them making it virtually a single, solid piece of steel. Far more solid than the limited contact provided by a dovetail design.


Unfortunately Paul I must disagree based on three points. 1. The two piece construction of your toolholder itself is a major source of flex that the standard Aloris style doesnt have, 2. if your toolholder is adjusted upward you lose much of any rigidity you had due to flex of the rather skinny toolpost itself, and 3. the small diameter of the spacer that the toolholder sits on. If you look at a typical QCTP, the main "block" of the post sits directly on the compound and typically makes for a nice wide base for the post itself, without this base needing to have any vertical adjustment. If the spacer between the post and the holder was a much larger diameter and the toolholder itself was one piece with a simple large screw to clamp it, it would be close to the rigidity of the dovetail QCTPs, but then repeatability comes into play and you would very likely be fighting a losing battle.

I do applaud your efforts at trying to create a better tool tho. Always gotta try for a better mouse trap.

uute
11-18-2012, 03:40 AM
It might take some searching, but there was a design similar to Outback,s where a round "piston" ran thru the dovetails, locking via a thru-bolts like his does. You cut the dovetails w/ piston in place (bolted tight w/ washer under them. Seemed quick, simple & solid to me. Easily made to standard dimensions to use standard tool blocks.

uute

vpt
11-18-2012, 09:54 AM
http://i107.photobucket.com/albums/m287/jackary2003/P1030617.jpg




All of that looks beautiful! I assume you made the compound as well? Very nice job!


My first project on the lathe when I got it was to make a QCTP. I made the entire thing on the 10" atlas with also using a milling attachment. Piston type, not sure on exact repeatability of the tool (never checked) I just set the tools once and forget about the setting. Haven't had any trouble with anything yet.

http://img175.imageshack.us/img175/7198/ebay010.jpg

http://img189.imageshack.us/img189/9827/ebay015b.jpg

Lew Hartswick
11-18-2012, 10:26 AM
Dovetails are all well and good but a LOT harder to make than 90 deg V's .
So the toolposts on the Clausing/Metosa lathes at school are some Spanish
MH 90 things that I have reproduced in aluminum quite a few times and made
a scaled down version for a South Bend for the teachers home shop. I have
some pix. someplace. If I can find them shortly I'll post a pix or two.
...lew...

GadgetBuilder
11-18-2012, 11:49 AM
John Stevenson posted an interesting dovetail design some time ago:
http://www.metalwebnews.com/howto/toolpost/toolpost.html

And here's the standard round toolpost with clamping toolholders:
http://www.homemetalshopclub.org/projects/toolpost/toolpost.html

Just more ideas for your design.

MLAToolbox
11-18-2012, 06:03 PM
JACKARY, compliments on your nice looking version of the MLA toolpost. Also, the topslide compound it's mounted on is sheer elegance.

I would just like to bring up one thing, that with the original, prototype version of the toolpost it was found that the dovetail clearances in the relaxed position should be around four or five thou., ideally, if I remember correctly, and not to exceed about seven thou. Those tolerances were easily accomplished by gauging with the toolpost body when milling the toolholder dovetails. I now have seventeen toolholders of various types, and presently there is no urgency to make more. When there is, should there be access to a milling machine, I would consider pre-milling the dovetail in a long slab of steel and, as needed, sawing off from it toolholder blanks like slices from a loaf of bread. The key would be in milling the dovetail with reasonable accuracy, so that the toolholder blanks would all fit equally well, rather than equally poorly.

A friend and I, using his milling machine, made a pair of larger versions of the original, prototype toolpost, with the intent that one of them would be used on his South Bend heavy ten lathe, using the large collection of Aloris and knock-off Aloris toolholders he already had, as well as some he had made.

During that project we decided to measure the dimensional variation, or "allowance" among them, and found the variation to be too great to be accommodated by the MLA toolpost without alteration. I forget what the variation was--I think I could look it up--but it was quite significant. Which does point to one advantage of the wedge type toolpost, in that it is fairly tolerant of dovetail dimensions. That can be seen, if I recall from my friend's lathe, in the various positions the Aloris locking handle assumes depending on the toolholder mounted.

That is certainly not to discourage the choice of the MLA toolpost in favor of the wedge and plunger types. The MLA is more easily made by the amateur machinist than the others, and in my opinion is more rigid, having full dovetail engagement with no interposed pieces. I mention it to point out that the cheap knock-off toolholders might not be suitable for the MLA toolpost, as suggested in a comment a while back.

JACKARY, it might be interesting finding out if you have measured the dimensional variations, or "allowances," among the dovetails of the toolholders you've made so far. Though I have to say, just from a feeling I get looking at the photo of your toolpost, that yours appears more flexible, and capable of greater expansion, than the prototype, and so more capable of accommodating greater variations in the toolholders. Again, compliments on a nice looking job.

uute
11-18-2012, 06:05 PM
GadgetBuilder, that's the one I remember, Sir John's wedge post!

outlawspeeder
11-19-2012, 01:09 AM
vtp is a kind of wedge but I have not seen any two wedge designs? Anyone?

jackary
11-19-2012, 06:04 AM
MLAtoolbox, I have cut through the dovetail block in the centre outwards to the the rounded notch at the back of the toolholder so that the block is only about 4mm thick at the back this seems to give enough locking expansion. I have only one other toolholder at the minute which also just slides into position when the handle is undone. I think you are right about it is best for the dovetails to fit good for the best results so I only intend to make any new toolholders a similar close fit. This will ensure the best results. Thank you for your kind words and good design.
Alan

Paul Alciatore
11-19-2012, 01:03 PM
I beg to differ.

First, my post is not "skinny". As sized for a 9" lathe, it is 1.25" diameter with only a 1/2" central hole. Since it is clamped down with a centered stud, it is under compression which will further stiffen it in use. Kinda like pre-stressed concrete.

While true that my holder is not sitting against the base of the post, it is only a fraction of an inch (several mm) above it so there is not much of the post that is exposed under it. Any flexing there will be very small. And the dovetail holders are not sitting against any solid base either: they are hanging out to one side of the post with nothing under them. Again, their posts can flex just as much or more than mine can in this respect. My next paragraph also addresses this.

All of the dovetail style holders must make room inside the post for the locking mechanism, be it piston or wedge. This further weakens them. My post has only the one, axial, 1/2" hole needed to lock it down. All the rest is solid steel. Stated simply, their posts have more holes in them and less metal left for strength.

All dovetail style holders must rely on two rather small areas of contact (on the dovetails) between the post and the holder. In addition, the wings of the holders which form the dovetails are rather small and easily subject to flexing. They are stressed in a combination of modes and are much more able to flex than any point in my solid design. The fact that my holder wraps completely around the post provides an extremely solid joint between the two pieces. I find it hard to imagine a better joint and in my humble opinion: the joint between the post and the holder is the worst part of the dovetail designs.

As for the repeatability of successive mountings, has anybody ever really tested a dovetail design in this respect. I would suggest trying a little pressure to the left and then to the right on the tool tip while mounting one. Can the dovetail design overcome such sideways pressures and still be repeatable? I would bet that some may pass this test and others (cheaper ones?) may not. I am sure mine will pass. Wear on the dovetails may be a factor here as the flats may become slightly rounded with use. The large, flat locating surface on my design provides a very dependable locating mechanism and any slight or even moderate wear should be self compensated.

By "spacer" in your third point, I assume that you mean the height adjustment screw. The dovetail holders also have an adjustment screw, usually with two nuts to adjust and lock them. Like my holder, their holders do not sit on a solid base: both are supported in the vertical direction by these screws BEFORE THEY ARE LOCKED DOWN. The diameters of these screws in the two designs are probably very similar, if anything, my 1/4" size is probably larger. And, to be fair, both designs do NOT depend on this screw as the main mechanism to hold the holder up in use: friction in the locking of the holder to the post is the main factor here. Differences? Well, my screw is under compression while there's is in a combination of tension and torsion (the nut only rests on the top of the post on one side). I claim the high ground here. Theirs has a problem with backlash when locked with the second nut. Mine doesn't. And a note on the vertical holding power of the two designs. It is a lot easier for the forces of cutting to drive the dovetail holders downwards. The relatively small holding surfaces of the dovetails will provide a LOT less friction than the wrap around contact of my design. So their spacer screw is called on to do a lot more of this support function than mine is. A lot more. If you don't believe this, take the nuts off a dovetail holder and try a heavy cut: I bet on instant disaster.

A side by side test would be nice, but, lacking that, I still believe my design is superior. By a long shot. My use of the post seems to confirm this, but I do admit this is not a scientific test.

Frankly, the more I think about the comparison between the two designs, the more I think mine is a lot better.



Unfortunately Paul I must disagree based on three points. 1. The two piece construction of your toolholder itself is a major source of flex that the standard Aloris style doesnt have, 2. if your toolholder is adjusted upward you lose much of any rigidity you had due to flex of the rather skinny toolpost itself, and 3. the small diameter of the spacer that the toolholder sits on. If you look at a typical QCTP, the main "block" of the post sits directly on the compound and typically makes for a nice wide base for the post itself, without this base needing to have any vertical adjustment. If the spacer between the post and the holder was a much larger diameter and the toolholder itself was one piece with a simple large screw to clamp it, it would be close to the rigidity of the dovetail QCTPs, but then repeatability comes into play and you would very likely be fighting a losing battle.

I do applaud your efforts at trying to create a better tool tho. Always gotta try for a better mouse trap.

outlawspeeder
11-19-2012, 01:47 PM
How does a two wedge lock work? I found one that pulls in from the corner for both at the same time. I am not sure about this type.

But I cannot think of HOW the wedge locks two without one being installed. and keeping it right.

So many choices.

machinistjh
11-19-2012, 08:10 PM
Here's one I've been working on for my SB 9". Roughly AXA sized.

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=73&d=1353370084
http://bbs.homeshopmachinist.net/attachment.php?attachmentid=72&d=1353370082
http://bbs.homeshopmachinist.net/attachment.php?attachmentid=71&d=1353370079

outlawspeeder
11-19-2012, 09:05 PM
You still have 3.5 disks? hahahaha

Looks good. did you do two cams on the lock or one?

machinistjh
11-20-2012, 02:18 PM
Sadly, yes we still use floppys because our Chevalier CNC has a disc drive and no networking card. I kept it simple, made one cam with .040" offset. I'll try to post more pics tonight.

outlawspeeder
11-20-2012, 03:49 PM
I am trying to figure out how to do two cams,... end mill it on a rotary? Two cams, one low one high. Or run two pins, one high and low for one side and one center...

I still looking to see how to do a wedge style. If someone can post photos of a store bought one….
I just can’t think how to lock two wedges.

Jaakko Fagerlund
11-20-2012, 04:21 PM
Sadly, yes we still use floppys because our Chevalier CNC has a disc drive and no networking card. I kept it simple, made one cam with .040" offset. I'll try to post more pics tonight.
Little OT, but have you considered buying a floppy to USB converter meant for that purpose? Csts something like few tens of dollars probably and lets you use a regular USB stick in the machine. The machine still "sees" a floppy.

Paul Alciatore
11-20-2012, 11:30 PM
Sadly, yes we still use floppys because our Chevalier CNC has a disc drive and no networking card. I kept it simple, made one cam with .040" offset. I'll try to post more pics tonight.

You think that is bad? Up until about four years ago I had to maintain and support a PC-XT at work which used 5 1/4" drives with the 180K disks. Our computer department wouldn't touch it, I had to do it alone. Operating system, software and all data was stored on those disks and I could not upgrade the data disks to another format because the software was no longer supported - except with laughter. I actually had to hide a couple of these old machines from the CEO so he wouldn't trash them. I needed them for parts. Evan was nice enough to send me some disks when I found out that I could no longer buy them. When we finally replaced the system the guys had turns with a sledge hammer on that computer. I led the line.

kitno455
11-21-2012, 09:16 AM
I am trying to figure out how to do two cams,... end mill it on a rotary? Two cams, one low one high. Or run two pins, one high and low for one side and one center...

I still looking to see how to do a wedge style. If someone can post photos of a store bought one….
I just can’t think how to lock two wedges.

You can see the repair parts diagram in a pdf on the aloris site. It uses an acme threaded cylinder, which pushes the wedges down and out.

allan

RussZHC
11-21-2012, 10:23 AM
If you dig around a bit you should also be able to find parts diagrams for Dorian and DTM, they, along with Aloris usually claim their designs hold better and with more repeatable accuracy. As well you may also be able to find KDK diagrams (single holder design) though I think some of their "holding abilities" could be related to the shape of the holders (that is just an opinion, I believe the holders sort of wrap around a corner of the post).
IMO one of the values of making your own, should be that you could design it so all the locations where things are "normally"held in space could be touching another surface. I am thinking particularly of how each holder for a non-specific set-up is held by the wedging or pushing action on its own rather than touching a surface below.

vpt
11-21-2012, 10:53 AM
I believe people try to hard with the tool post/holder. I have the simplest piston style and have yet to ever see any problem of a loose tool or the post moving. Even when chattering the living dickens out of the lathe I have never had the tool loosen up or move.

machinistjh
11-23-2012, 10:51 AM
Sorry I'm a little slow getting back here. I finished my tool post the other day, everything turned out very well. I was worried that I may have to mill some off the bottom of the holders to be able to get low enough for the cutters. Not a problem. It looks a little big for my 9" lathe, but I think it will be fine.

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=74&d=1353681745
http://bbs.homeshopmachinist.net/attachment.php?attachmentid=75&d=1353681770
http://bbs.homeshopmachinist.net/attachment.php?attachmentid=77&d=1353681816http://bbs.homeshopmachinist.net/attachment.php?attachmentid=78&d=1353681832

uute
11-24-2012, 02:36 AM
That did work out Nice!

Well done.
uute

thaiguzzi
09-09-2014, 01:30 AM
Hi outlawspeeder I have just built a variation of the MLA toolholder and I am pleased with the outcome. I does not index because I do not do much repetition work, it locks both the toolblock and at the dovetail with just a slight tightening of the central handle. I have fitted it to a new topslide (compound) for my Chipmaster lathe. The plan was to minimise the cantilevered overhang of the toolholder.
http://i107.photobucket.com/albums/m287/jackary2003/P1030617.jpg
http://i107.photobucket.com/albums/m287/jackary2003/P1030612.jpg


Alan

Sorry, old thread i know. But just want to say that is a most beautiful version of the MLA QCTP, beautiful top slide (compound) on a fantasticly clean Chipmaster (great lathes). Compliments of the highest order.

Paul Alciatore
09-09-2014, 04:41 AM
Very nice looking build.

Happy Chips!

PStechPaul
09-09-2014, 07:59 AM
I like the design of that toolpost. It's very clever how the clamping knob simultaneously spreads the body of the post into the notches of the dovetail as it also clamps it to the compound. It seems to be something I could make. I just got a small 3/8" 45 degree dovetail cutter that should work for something like this. I found import toolholders for about $20 each:
http://www.ebay.com/itm/NEW-AXA-1XL-OVERSIZE-5-8-QUICK-CHANGE-TURNING-FACING-LATHE-TOOL-POST-HOLDER-/131242809520

vpt
09-09-2014, 08:30 AM
Sorry I'm a little slow getting back here. I finished my tool post the other day, everything turned out very well. I was worried that I may have to mill some off the bottom of the holders to be able to get low enough for the cutters. Not a problem. It looks a little big for my 9" lathe, but I think it will be fine.

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=74&d=1353681745
http://bbs.homeshopmachinist.net/attachment.php?attachmentid=75&d=1353681770
http://bbs.homeshopmachinist.net/attachment.php?attachmentid=77&d=1353681816http://bbs.homeshopmachinist.net/attachment.php?attachmentid=78&d=1353681832



Old thread day today?


Curious if you are still using the socket screw or if you ever put a handle on the compound bolt as well?

A handle on the compound bolt alows for quick turning of the tool post which I feel happens just as much as tool changes if not more.