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Old 06-03-2009, 05:14 AM   #1
Majorstrain
 
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Default Making a QCTP (Quick change tool post)

Just thought I might share my progress on making a QCTP for my lathe.
The original tool post is the standard type that is 75mm square and 65mm high. The new tool post is based on a design that pulls the tool holder into the tool post.

When I finish the QCTP I'll finalize the drawings and post them in the plans section (I imagine I'll have lots of changes due comments and the process of making the parts), but until then here is what I have so far.

Your suggestions and comments are most welcome

Cheers,
Phil

QCTP_70mm.pdf
STD_holder_70mm.pdf

These files updated 6-6-09
Changes: dovetail dimensions given using rods 6mm or 1/4" rods
section D-D view direction corrected for looking at base from under side, not from top through.



QCTP_70mm.pdf
STD_holder_70mm.pdf

These files updated 21-6-09
Changes: Drawing now have truncated dovetail corners (chamfered).



Attached Files
File Type: pdf QCTP_70mm_Assembly.pdf (1.36 MB, 2571 views)
File Type: pdf Parts_70mm.pdf (62.5 KB, 1731 views)
File Type: pdf QCTP_70mm.pdf (250.5 KB, 1602 views)
File Type: pdf STD_holder_70mm.pdf (48.7 KB, 1466 views)
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Old 06-03-2009, 05:27 AM   #2
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Default Re: Making a QCTP (Quick change tool post)

I manged to scrounge some 4130 bar stock the was 90mm in diameter and 85mm long.
I skimmed the sides and squared up the ends on the lathe.



Then proceeded to turn it into a square bar on the mill. A quick note : 100mm bar stock is required to get the full 70mm square, Since I only had 90mm bar the corners will have a rounded edge. No great loss I think.





When that was done, I roughed out the dove tail slots.



Now I just have to wait until I buy, make, or borrow a 60° dove tail cutter.

Cheers
Phil



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Old 06-03-2009, 10:08 AM   #3
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Default Re: Making a QCTP (Quick change tool post)

Looks like a copy of a Hardinge...It's a good post!

I built one like it some time ago for my old Atlas lathe



I used an 11/16" hex head bolts to match the Atlas supplied wrench, but the rest is nearly identical...and you will like having two clamp bolts as it really locks the post down.

The key is to cut the two female dovetails the same time with the clamp nut, the arrow shaped part, in the post and spaced out say .03" with a washer while your cutting it. After you cut both dovetails and the clamp nut, remove the washer

I would make the dovetails to roll dimensions, not to the apex dimensions shown on your drawing as there is no way to measure an apex dimension. Put two 1/4" diameter or so ACCURATE dowel pins in and machine both female dovetails to the same dimension. If you measure between the two rolls, you can measure it very accurately, especially with guage blocks or even an adjustable parallel in between the two rolls. If you do that with the clamp bolt in place it will clamp at the same handle position with tool holders in either position. That will be very welcome in use.

For holders, get a long bar and cut the required dovetail full length, to a roll dimenstion again, then part off the individual holders from there.

Hope that helps! You'll like the toolpost!

Regards,
Dave

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Old 06-03-2009, 10:33 AM   #4
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Default Re: Making a QCTP (Quick change tool post)

Yep, I've modified it to make it easier for me to make.
The operating theory is basically the same.
I'm thinking about making the mechanism a cam lock arrangement rather than the screw system.
I'll give it some more thought when I get to that stage.

Cheers
Phil

Nice pic, What metal did you use Dave?

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Old 06-03-2009, 10:49 AM   #5
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Default Re: Making a QCTP (Quick change tool post)

....Nice pic, What metal did you use Dave?...."


Scrapboxalloy ........I think It was a chunk of 12L14, complete with rounded corners like yours......it ran for 5 years and went with the lathe when I sold her. No issues.

The Arrow piece was 4150 HT though.....I had a female thread in that piece and that IS a wear item.
No troubles with mine though.

The parts don't really rub together ( other than the arrow) with any pressure so as long as the mating surfaces are kept clean, your good.

Dave

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Old 06-03-2009, 11:14 AM   #6
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Default Re: Making a QCTP (Quick change tool post)

Phil,
I thought about it a bit and think you should stick with a clamp bolt. It would be tough to make the camlock feature as part of that clamp. Maybe a sacrificial clamp bolt used while you machine the camloc and dovetail features into the clamp.... maybe?....haven't thought about it beyond that.
Cool thing is if you use the design you currently have, the toolpost becomes the fixture to machine the clamp bolt.......I hate making fixtures!

....A clamp bolt was good enough for Hardinge.........

Dave

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Old 06-03-2009, 11:24 AM   #7
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Default Re: Making a QCTP (Quick change tool post)

Quote:
Originally Posted by steamer
It would be tough to make the camlock feature as part of that clamp. Maybe a sacrificial clamp bolt used while you machine the camloc and dovetail features into the clamp.... maybe?....haven't thought about it beyond that.
Cool thing is if you use the design you currently have, the toolpost becomes the fixture to machine the clamp bolt.......I hate making fixtures!

....A clamp bolt was good enough for Hardinge.........

Dave
Your absolutely right Dave, I'll stick with the bolt idea. The sacrificial blot is a great idea also.
Thanks
Phil
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Old 06-03-2009, 02:28 PM   #8
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Default Re: Making a QCTP (Quick change tool post)

Phil very nicely done plans so far. What kind of flood coolant are you using and how long have you been using it? I ask because I have a mister right now and want to add flood coolant to my lathe and mill.

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Old 06-03-2009, 04:08 PM   #9
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Default Re: Making a QCTP (Quick change tool post)

looking good Phil, great idea having the locking lever on the side out of the way ,i think i may build one for my larger lathe.
Rob

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Old 06-03-2009, 07:26 PM   #10
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Default Re: Making a QCTP (Quick change tool post)

Hey Majorstrain
Really liked your post I am planing on making a QCTP for both of my lathes I like the way your making yours. What size lathe are your prints for. Keep up the good work I might use your prints if you don't mind Cliff.



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