QCTP mount take 2

[xnaron]

Well I sold my brand new 10x22 lathe the other day after less than 30 days in my shop. My first project on it was the QCTP mount. Anyhow onto lathe #2 well actually #3 as #1 was a 7x12.

I picked up a 12x28 (really probably an 11x27) just before selling my 10x22. This time I bought the wedge AXA QCTP. Last time I did this https://www.hobby-machinist.com/threads/quick-change-tool-post-for-10x22-busybee-cx706-done.81966/

This time I think I want to keep the ability to use the 4 tool stock holder. The plan is to bore out the bottom of the AXA QCTP to fit the stud on the cross slide. Only a slight amount of widening will be required. Then I want to turn a threaded adapter nut column (4140) that will fit down into the tool post and tighten it into the stock 10mm bolt. The stock 10mm stud does not go past the top of the tool holder. I have seen other people use this approach before. There will only be 0.2" of material diameter left on the adapter to mount to the 10mm stud (see pic with 0.1" radius). There will be a fairly long engagement of thread though to hold it in place. Anyone have a better idea?

 

[mickri]

I like your idea. I have often wondered/thought about trying to do something similar for my lathe. I made a norman style QCTP for my lathe. It would be handy to have 3 tool bits on one tool holder. A general turning tool bit, a facing tool bit and a chamfer bit. I seem to use those 3 tool bits a lot. Often to save changing the tool holders I just use my general turning tool bit for facing and chamfering.

 

[mikey]

Nope, that should work.

 

[darkzero]

Yup, agreed, should work just fine.

I had a DTM tool post and the stud was the same way, shorter than the tool post, much shorter. It used an extended blind nut instead of an open flange nut that's commonly used. That was how the DTM came stock. I miss that tool post.




My first QCTP on my old mini lathe was also like you mentioned. Bottom bored out to fit over the stock boss on the compound. I didn't do the boring though, it came that way, was specifically for that model lathe. Here you can also see how far the nut extended down through the DTM.

 

[xnaron]

Thanks guys. It looks like it will be hard to try and take this qctp apart like I did with the piston one when I bored out the hole. I checked and it should fit in the four jaw chuck without taking it apart. I'll take it slow...

 

[xnaron]

Mistakes were made. I thought I would be able to bore out the bottom of the tool post 22mm diam by 18mm deep. I was wrong. I hit threads and the mech holding the tool post together let go. Sigh. Should have put more thought into it. I wanted to keep the stock stud in place but it wasn't going to be possible. Also the stud is different than what was on my 10x22 lathe. The shoulder on that one was part of the cross slide. On this one it is on the stud and the whole thing is press fit into the cross slide. I made a plug out of 4140 similar to the one shown below but only 0.125" protruding above the table. I threaded the hole for the new stud to 9/16-18 (weird on a Chinese tool to not be metric).

Lessons learned. This tool post is still usable as is but I had ordered a replacement before working this through in case it wasn't. Last picture shows one tool holder I needed to mill about 0.1" off the bottom to allow the parting tool to line up to the center line. The other tools can be adjusted without issue. In retrospect I should have probably just made the new insert just shy of flush with the cross slide top and that would allow mounting the tool post without modification. Maybe I'll make another one...

 

[Thriller]

Thank you for all the pictures in the write up. Brand new here and it’s nice to see people working on lathes like mine.

 

[Chipper5783]

Modifying the tool post and holders is certainly fair game. I ended up making new center bolts for both the QCTP systems that I have installed. Every lathe seems to be a bit different - it seems that having no modifications would be the exception.

I did the tool holder mods for the one lathe using my other lathe (must have at least two). The arrangement was to bolt up the tool post, then grip the holder with the post - worked great.

Good job on your mods.