A different QC Toolpost

This is from an original design by J A Radford and was featured in the Model Engineer.
The main advantage of this design is that it can be made without the use of a milling machine as indeed was mine and has been in use for 40 years on my South Bend.
I can vouch for its sturdiness in use and it will still repeat to .0005 inches, it also gives a little more room when working close to the tailstock.
Mr Radford as I recall made a drilling jig for the dowel locations and drilled and reamed on the bench drill.
I did not follow that approach myself and instead jig bored them using my vertical slide, I am glad I did as I have only recently made some more tool holders and after all that time I doubt I would have found the jig.

I do not have the original drawings but have re drawn it to scale on 3D Cad (Sketchup) and have taken a screen shot to show the parts. The sizes are to suit your preferences but on mine the dowel ctrs are 2 inches and the centre clamp ram is .750 inches. The only other relevant dimension is the offset of the cam clamp which is .0625 (could be a little more say .075). The keen eyed will notice that the drill rod location pegs are screwed to the main block, I think that modern adhesives would probably do the job just as well.

Attachment 12384Attachment 12383Attachment 12385Attachment 12386

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Thanks olderdan! We've added your QCTP to our Machining category,
as well as to your builder page: olderdan's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/qctp-4"> <img src="/uploads/153756/qctp-4.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/qctp-4">QCTP</a> <span> by <a href="http://www.homemadetools.net/builder/olderdan">olderdan</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/qctp'>QCTP</a>, <a href='http://www.homemadetools.net/tag/tool-post'>tool post</a> </div> </div> </div> </div>
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Hello,

Nice build. Thanks for the photos and plans.

A question please ?

Once you have turned the lever and pulled the piston tight is it possible for the lever to loosen again or is there some sort of locking mechanism that I haven't seen or understood ?

Bill

Hi Bill,
Thanks for the comments.
In answer to your question there is no need for any extra locking device as the cam itself provides all the force and security needed.
I have used this holder for many years sometimes on heavy interrupted cuts as well as parting of and it has never loosened in use.
Indeed I have kept the clamp lever short to avoid to much force being applied.
It grips so well that sometimes it is necessary to give the end of the ram a bump with the hand to unstick the holder.
Hope that helps.
Alan

I really like this design because of the sturdy low clearance. Interesting you did it all on your lathe.

Thanks for sharing the pics and drawings.

Turning hardened steel.
It is possible to turn sintered and Hss steel up to 65 Rockwell accurately with the right tool.
The tool tip required is a CBN (Cubic boron nitride), not cheap but they last a very long time with careful use. If you have an irreplaceable part to refurbish it can be an alternative to grinding with a comparable finish.
Case hardening on old motorcycle parts is usually around .010 thou deep and it is possible to skim off .002 Dia with this method.
Attachment 12437Attachment 12438


Mid range speed and finest feed no coolant.


Make new bushes to suit and good as new.
It is usual to sharpen the top face only on these tips with a diamond wheel (I have only needed to do that once in a dozen usage).

olderdan,

This is a good design for the QCTP and interesting story about building the parts without using a milling machine. How did you make the semi-circular grooves for the tool holders? Is it possible to make a pair by drilling (or boring) two holes spaced at 2" centers and then use a bandsaw to split the pair? More information about how you set up your milling work on the South Bend lathe would be interesting to know.

Thanks for sharing the photos and drawings. Also thanks for the tip about using CBN tools.
Regards, Paul Jones

Hi Paul,
After milling the blanks I clamped them in pairs and and drilled and reamed them on the centre line using co-ordinates with the vertical slide and cross slide.
Has the advantage of doing two at a time, after which I milled about .015 of the mating faces.
After milling the large clamping T slots ( vertical slide again) , I used the tool post itself to mill out the tool slots.
I hope to post more info on some of my milling setups soon.

My vertical slide is made from a large Colchester top slide and is nice and solid.

How can I get some plans for this very nice toolpost?
jhewitt5@wi.rr.com

Attachment 18551

Well gonna try and use your style for my own tool post. Going to try and use 16x60 hardened and ground dowels for some extra durability. Not designed one of these cams before so accidentally ended up with 5mm of movement rather than the 1.8mm I was shooting for so more iterations to come

Looks like that's where HBM got the idea for their toolpost.

https://goo.gl/8ZSEnJ

I bought one a few years ago for my Myford as a cheap alternative to the Dickson and never regretted it.

Seeing I visited this toolpost post nearly a ago, an email reminder brought it all back. I don't know of Mr. Radford olderdan refers to, but his design is an excellent take on the European favorite. Can't track down the originator or copyright but versions are Swiss and Italian for sure, likely there are others.

Won't paste the search link, it is ridiculous in length so I'll suggest Google Italian Lathe Toolpost, and Quick Change Toolpost, in images. plenty to examine. If you do more than one variety or quantity of lathe work, that might justify more than one toolpost. This is my go-to, next is Aloris, then indexing turret. I have a rare KDK turret for second op and light work. There are benefits to each pattern, none have ideal configuration. This variety has the most positives in my book. Narrow, in depth of post to part. Less bulk/ weight than the very good Aloris pattern, more along KDK. Weakness of KDK is dovetail fights leverage of a bit too far from the clamping action. Cool for chucking & second op work, hate them on good-sized lathes.

Both olderdan and Rainbows capture the best aspects; rigidity in vertical axis close to the bit as practical, and easily made. Rainbows initial design lacks orientation of a transverse bit, hampering cutoff and threading tools. Both locate by use of ground rod, where commercially made is with ground vee's. i also like olderdan's adjustment screw, positioned well above top of holder.

What do you mean by transverse bit?

Also here is something to consider with these round dovetails.
We are reaming the holes so the hole will be ever so slightly bigger than the rod.
Attachment 18554
Exaggerated the size difference for show, you see the pin and groove mate in one area.

Now having assembled the toolpost, what if I rubbed the side with the pins on a piece of wet and dry on my surface plate?
Attachment 18555
By making a flat on the edge of the pin the groove now seats on the rod in two places instead of one.


Also I am making a solid toolpost, one without a compound slide, Robrenz on youtube does a very good video on how he mounted his toolpost. Im gonna copy him in using a few dowel pins to align the toolpost about its axis.

Distributing contact is a good idea, such you might get flattening the front of pin. I'd think reaming pin size plus .0005 or .001 will be very good alignment and repeatability.. With access to CAD or some calculating offset of the reamed contour/ pin size would reveal ideal combinations. By offset, I mean percentage of 'hole' remaining and protrusion of pin. Clamping has to be on the Radii, not face of post. .030 clearance wouldn't hurt a thing. Reamers by the way are available in near every diameter desired.
[edit additional] occurs to me that enough flat to get contact at 45 degrees would be worthwhile.

To insure the greatest similarity among holders, I'd;
Mill the blocks completely first, with to-be-removed material supporting drilling area.
Drill the holes in all blocks one side [right or left] at a time, located by a stop.
Bore those about .015 -.025 undersize at the same setting of boring head, also one end at a time, with same stop set up. Need be, rough bore first, allow clean up so 1 setting will cover all the holders, Same center-to-center, size, surface finish, and parallelism one and all. Reaming won't correct variance in center to center difference, ever. Similarity=repeatability and makes or breaks a QCTP.

And by transverse bit, I imply bits mounted in holder along side of post such as threading. You may of had that in mind, but only one drawing was shown, so...olderdan's "family shot" depicts holders slotted along face and side. You'll save yourself a LOT of tedious grinding in what would normally be conventional cutters. I don't recall what accommodations were made for cut-off tools, but setscrews shouldn't bear directly on upper surface!

Retention of bits in general, coarse threaded set screws are more common, but my preference leans to fine; more secure with the same amount of torque. I'd want 3, spaced for the bit length you use, corner obviously works either direction. Use dog or flat points not cupped, they mar tools. Advantage to dogs, when they mushroom and they will, they're still removable.
If you use square heads and a nice little wrench, it's better than a socket filled with chips. Possibly better feature is durability, the square head employs far greater wrench engagement. Ever round out a hex socket? Ever see a worn square; sure, from horrible abuse.
Attachment 18556
Buy a whole box if you can, they don't go stale or shrink, but cost is sure to rise.

"Advantage to dogs, when they mushroom and they will, they're still removable."

Thanks for all that TM51, but the above and about square heads answers some brain worms that have been bugging me about "why" on my old Atlas 7b. I saw on another forum where a guy added a couple of locks on the cutter head on his 7b so I did it to mine.

He explained that he added the locks because on a shaper you need the gibs tight so they stay put when cutting. But if you have them tight enough to stay it makes it hard to adjust and is really hard on the lead screw and nut causing them to wear faster. I was also having a problem with keeping dimensions in a pass and thought this might be a good mod.

I couldn't order the adjustable handles with the dog point so I put them in my tool grinder and made them into dog points. Not knowing anything except that the other gib adjusters were all dog point. Now I know the reason for dog points! I also couldn't figure out why the gib adjusters all were square heads, now I do! I also cut the eye brows into the gibs so the dog points didn't gouge the gib. In the end it worked perfectly even though I didn't know the specific reasons for what I was doing, only copying what I would call historical engineering.

Would you share the Sketchup file?

Ralph

I too would love a set of tech drawings even cad would be awesome!
charron63@gmail.com

Quote:

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Originally Posted by Rainbows

What do you mean by transverse bit?

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Somehow I neglected responding to the question...It seems one of two things.
1 is only the block shown doesn't extend beyond side of post, inhibiting a parting tool. Yes, the drawing focuses more on the mechanical QC aspect, not block features.
2nd, the minimal alignment in two parallel lines of contact almost guarantees binding when pressure pushes down on block/ toolholder combination. I'd still ream size for size with 60% something offset of the pin in post. That will retain them [dowels are +.0001 or .0002] in post. The holder cavities will then engage outer extreme remaining 'edge', reducing movement perhaps 400%. Clearance would remain at face of post and holder, .010 sufficient. Flats on pin faces directs alignment to wider point of diameter, without gripping the full half.
I've prepared an exaggerated sketch.
Attachment 33015