1127 solid tool post mount

ttabbal

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Inspired by this thread, https://www.hobby-machinist.com/threads/solid-tool-post-mount.67428/...

I ended up changing things around a bit for material availability. The base is made from 7075 aluminum, with a piece of ground steel plate on top.

The stud is threaded to match the original M10x1.5 so I can reuse my top speed handle. I went with 3/8-24 for mounting to the top plate as imperial threads are easier on this lathe and I have a nice tap for that size. I milled a couple of flats to make it easier to tighten/loosen.

I need to get some shorter bolts for mounting to the t-slots.

IMG_20181008_222909.jpg
 
Looks nice and solid - good job!

Does it work well?
 
I should be able to find out tomorrow. I can't bolt it down yet. :)

Or I could grind ~3/4" off the other 3 bolts, but I'm not feeling that tonight. :)
 
Wow. I'm liking this setup! I did a little diameter reduction increasing DOC keeping feed the same, though I did increase speed for the last cut...

IMG_20181009_220928.jpg


Nice feeling finish for every cut. The last one was 0.250" DOC leaving just over 0.030" on the stock. Zero chatter. That's a 3/4" 12L14 bar. Granted, it's 12L14, but that's over 2x the cut I used to get a little chatter on and I could do more, but I ran out of stock. :)

One issue, the handle for the top nut ended up clocked toward the headstock. It's not an issue at the moment, but I suspect the regular chucks will disagree with it being there. I'll have to set it up for a new hole.

Correction, 0.250 diameter reduction. 0.125 DOC. Oops. ;)
 
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Nice cut. Is the OD on that 0.030" remnant consistent from end to end? If so, that is a really nice cut. Bet your parting off will be better, too.

A simple washer under the top nut will fix the clocking issue. Just adjust the thickness to produce the positioning you need.
 
Wow. I'm liking this setup! I did a little diameter reduction increasing DOC keeping feed the same, though I did increase speed for the last cut...

View attachment 277307

Nice feeling finish for every cut. The last one was 0.250" DOC leaving just over 0.030" on the stock. Zero chatter. That's a 3/4" 12L14 bar. Granted, it's 12L14, but that's over 2x the cut I used to get a little chatter on and I could do more, but I ran out of stock. :)

One issue, the handle for the top nut ended up clocked toward the headstock. It's not an issue at the moment, but I suspect the regular chucks will disagree with it being there. I'll have to set it up for a new hole.

Correction, 0.250 diameter reduction. 0.125 DOC. Oops. ;)
The solid tool post made a big difference on my PM1127 as well, especially when parting off. I’ve also been able to set up all of the tool offsets in my DRO since the position of the tool post is fixed.
 
You know, I hadn't thought to test the remnant. I got out the mic and I'm reading 2 thou larger at the tip. The rest is under a thou difference. Not bad considering I wasn't really trying to do it. I haven't tried parting on it, but I will soon. I also have the parts to try building a camjack knurler so that will get tested. I've never bothered to use the bump knurler.

A washer. I really should have thought of that. :) How would one turn it for thickness though? Super glue mandrel clickspring style? I've never tried to hold something like that. I guess I could do it in 2 operations, hold from the center then switch.. Of course, the ones I have might just be the right thickness to start with. :)
 
Try a wax chuck,

19-08-2018-004.JPG 19-08-2018-006.JPG 17-08-2018-003.JPG
That is a piece of 1/8" brass plate. It is secured by means of shellac used as an adhesive. The last picture shows that it is just a piece of aluminum turned so it can be held square in the chuck jaws.
 
I’ve used brass 5C “emergency collets” to hold onto thin parts. Not sure if there’s something similar for ER collets.
 
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