Making a QCTP (Quick change tool post)

[Majorstrain]

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).


View attachment QCTP_70mm_Assembly.pdf

View attachment Parts_70mm.pdf

View attachment QCTP_70mm.pdf

View attachment STD_holder_70mm.pdf

 

[Majorstrain]

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

 

[steamer]

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

 

[Majorstrain]

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?

 

[steamer]

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


Scrapboxalloy ;D........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

 

[steamer]

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

 

[Majorstrain]

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

 

[deere_x475guy]

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.

 

[RobWilson]

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

 

[Cliff]

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.

 

[Majorstrain]

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

WILCO Dave, I'm waiting for a dovetail cutter to arrive now, (tried making one using a triangle insert tonight. fabrication was successful to a degree, but not good enough for steel). I'll start on boring the wedge holes and and making the internals tomorrow, in prep for the combined dovetail operation you describe.

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.

Excellent point, I'll modify the drawings to suit, Thanks

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.

To tell the truth, I rarely use the flood system, I have mainly worked with aluminum and brass so far. The last time I used the flood system was when I made my 3" boring head soon after I got the mill about a year ago. The coolant is a soluble oil that I got from the boys at work, they have been using it for years. I'll find out what the brand name is tomorrow.

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.

Hi Cliff, The original tool post on my lathe is 75mm square and 65mm tall. Not real sure how to measure the lathe but it looks like it would swing 10" and be able to turn 25 -28" between centers. There is a pic of my lathe in this thread http://www.homemodelenginemachinist.com/index.php?topic=5029.0
The QCTP that this has been developed from was 60mm square without the holder and about 50mm tall. I have a set of drawing for that QCTP that I will update if you like.

Thanks for all the comments and suggestions, I'll see if I can get some more done b4 the baby arrives. T- 1 week and counting.
On the plus side the honey do b4 baby list is complete now. ;D

Phil

 

[deere_x475guy]

To tell the truth, I rarely use the flood system, I have mainly worked with aluminum and brass so far. The last time I used the flood system was when I made my 3" boring head soon after I got the mill about a year ago. The coolant is a soluble oil that I got from the boys at work, they have been using it for years. I'll find out what the brand name is tomorrow.

Phil, thanks no rush as I am not set up yet to use it anyway but I would like to start finding out what others are using.

 

[steamer]

Phil,

For a small lathe ( Say 10" and under), the basic Hardinge design is a great one.

I'm using a Phase II AXA wedge on my 1200 pound 12"x 39" Logan and it works great!

Either works fine.....one of them gives you bragging rights.... ;D :big:


Dave

 

[Majorstrain]

Got a good few hours in the shed today, the center hole is finished and the wedge slot cut in the body.

Here is the progress pics.


I don't have a 45° set square or angle plates so I used a V block and DTI to set the angle in the vice.

and now it's ready to start the center hole

I worked my way up to the largest drill bit I had (13mm) making sure not to pop out the bottom into the vice : . The hole doesn't need to go all the way through, just into the section that will be removed for the wedge block on the other side.

I used a 3" boring head and the longest boring bar I had that would fit in the 13mm hole. The hole was slowly bored out to 15mm and the full depth of the bar.

The handle end completed with the 3 different diameters. 15, 20 and 30mm.

Started roughing out the wedge slot and soon uncovered the tip of the drilled hole. That was probably a bit too close to popping out into the vice.

Wedge slot on the final cut, 30mm wide and 21mm deep from what would be the tip if my bar stock had been big enough.

Here is the wedge slot finished.
You may notice that there is a 20mm recess 2mm deep at this end of the center hole. The reason is that my boring bar was 1.5mm too short and the 15mm hole was not deep enough. To solve the problem I just centered the 20mm cutter over the hole and plunged it in 2mm. It should have no effect on the operation of the tool post.

There are a few things to add to the drawings, we'll see if I can get to that tomorrow.

Until then,
Cheers
Phil

 

[steamer]

It's looking very familiar.

I put my block on two rods to set up for the flat. You used a Vee block...that's about the only difference........LOOKING GOOD! :bow:

Dave

 

[Majorstrain]

I put my block on two rods to set up for the flat.
Dave

Interesting, could you sketch that for me Dave, I can't picture it. I know it will be blindingly simple when I see it.

Update time.
I finished the hold down holes today. That's enough for the mill until the dovetail cutter arrives, now it's back to the lathe to make the internals.

The top view

The bottom view

I learnt from the earlier boring depth issue, this time I bored the large radius first which gave me room to go deeper with the boring bar and not foul the tool shank.

The next two pics are for size comparison, the small lathe is on loan from a friend who has no space to store it.

My lathe with the old post behind the new QCTP

Friends lathe, quite a common unit badged for Hare and Forbes

Cheers
Phil

 

[Majorstrain]

Drawings updated, refer to first post.

Phil

 

[Majorstrain]

Well, after a few distractions I got back into the shed and spent some time on the tool post.
I finished the threaded insert, the retaining nut, and spacer. The metal is of an unknown grade.
I also had make a holder for an internal threading insert I had. ( that was successful after the third attempt :wall

My drawing calls for a M24x1.0 thread but I discovered that I don't have the change gears for the 1mm pitch, so I used a 1.5mm pitch instead. I imagine the making some change gears will soon follow.

The threaded insert completed

The retaining nut ready to part off

Parting off.

Didn't even drop it in the muck ;D I manage to drop the bits most times.

Stopped parting off the spacer half way so I could put a chamfer on the edge.

The completed parts and the internal threading tool.

Cheers until the next instalment,
Phil

 

[Majorstrain]

Managed to get about 4 hours in the shed tonight.

I finished the centre nut and did the turning on the leaver base. The leaver base just needs the lock screw drilled and tapped and the leaver hole drilled and tapped. Both operations I'll do on the mill.

Here are the pics.

This is the centre nut ready to part off. The M5 hole has been drilled and tapped.
I didn't have a left hand turning tool so I used my parting off tool to remove the material left of the large diameter. I was very careful to take light cuts and watch for tool flex. All went well.

The pic below illustrates my limited tool range at this time. oh:

After parting off the centre nut and turning it around in the chuck, I drilled the hole for the M10 tap.

When I tap on the lathe I usually put the tap in my tail stock keyless chuck and with the Morse taper loose I hold the tail stock chuck by hand and power tap at the lowest RPM.

Well with the M10 tap, the tap spun in the chuck and I could not get it locked tight enough. Holding the chuck by hand was still not a problem though.

After giving up on that method I went to my cheap tap set and got out the tap handle. Just my luck, the hole in the centre was just too small for the tap. :wall:

The pic shows how I ended up getting around the problem. I should note that I did not power tap using this method, I locked the lathe chuck using the back gear leaver and tapped a quater turn at a time.

Finally, the finished centre nut

The parts assembled with the centre nut.

To cut the chamfer on the leaver base I just set the compound slide to the angle required and advanced it by hand.

The progress so far with the leaver base in place.

Best regards,
Phil

 

[Maryak]

Phil,

This is going to be one very nice QCTP. :bow: :bow:

Best Regards
Bob