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- Mar 7, 2018
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Do you just swap the crossslide back when you need to do taper work?
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PM1340 Solid Tool Post for Dorian BXA QC
- Thread starter davidpbest
- Start date
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- Dec 26, 2015
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Depends on the taper and how the part has to be held. If the part is in a chuck, or if I'm cutting threads. , I remove the solid tool post and reinstall the compound - takes 5 minutes. If I'm cutting shallow but long tapers (example would be 0.500" change in diameter over a 10" long bar) I will offset the tailstock and turn the piece between centers with a lathe dog.
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- Oct 16, 2017
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- 338
What I don't like about this approach is drilling and tapping seven holes in the cross slide. Did you investigate the possibility of using T-nuts in the same manner that the compound is attached, and instead of a registration bar, making the tool post solid block slightly wider than the compound with a recess milled such that it straddles the compound or hangs over on the spindle side (you have a DRO scale on the tailstock side)? Just asking, I have not started my conversion yet but was thinking of different ways to mount the solid block.
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- Dec 3, 2013
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There is nothing wrong with drilling the cross slide. The circular t-slot does not provide for using a t-nut of substantial size. On my pm-1440gt I only drilled the 4 corner mounting holes and used cap screws with long shoulders so part of the shoulder engages the cross slide acting as a pin. My riser has a boss on the bottom that engages the center hole on the cross slide.
If you don't want to drill the cross slide I would make t-nuts at thick as possible to use in the circular t-slot and use four. Use a registration boss in the center pocket between the riser and cross slide. Have the forward edge of the riser hang over the cross slide edge or bolt a plate to the forward side of the riser that engages the cross slide.
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- Oct 16, 2017
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I don't want to drill the cross slide. I will probably mess it up!
Any reason the riser can't be made from cast iron? You can get gray cast iron 6"x6"x3" for about 60USD excluding shipping from Speedy. The same in 1018 would cost about 280 USD.
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- Dec 3, 2013
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Don't underestimate yourself. Easy with a mill. It is a simple drilling and tapping job, just requires some disassembly of the cross slide.
Cast iron is fine. I used A36, which if I recall was $45 at the time. Cast iron was 4x as much.
I currently have my cross slide apart for some straightening up of the sliding surfaces. One project I have had is making a solid tool mount and debated about drilling holes in the topslide just for the simple reason of room. The gib is on tailstock side/right side. The thickness of the top of the dovetail area is around 1/2. The circle slot area for the compound mount. There’s just no meat for even 1/4” bolts. Leaving a 1/8” on each side in cast seems like trouble. Then the depth the whole topslide is maybe a 1” or so with the dovetail part being the majority so if only going into the top portion and not near the dovetail meat the thread engagement would be less than 1/4” in cast. That will pull the threads out easily.
I’m in the process now but I’ve made four threaded disc for the circle keyslot in cross slide. They are snug fit in thickness and I cut the radius on Id and od threaded 3/8-16. My plan is to make the block which I have cast iron and drill four through holes and bold down that way. The block is registered from the center boss in cross slide so that’s taking the grunt of the forces the screws need to keep it secured to the cross slide.
One thing that no one has mentioned is the matting of the two surfaces. The bottom of the block need to be deadflat also the top area of cross slide. If one surface is smiling, frowning however you look at it. It will translate to the matting surface so now the backside of the cross slide might bow up or down. Idk I just got done bluing every surface on my cross slide and I’ll tell you there was not one surface that blued even 60% every one touch on the corners and raised in the center. Just a thought. Here’s a pic of the bottom of a 14x40 cross slide.
I’m in the process now but I’ve made four threaded disc for the circle keyslot in cross slide. They are snug fit in thickness and I cut the radius on Id and od threaded 3/8-16. My plan is to make the block which I have cast iron and drill four through holes and bold down that way. The block is registered from the center boss in cross slide so that’s taking the grunt of the forces the screws need to keep it secured to the cross slide.
One thing that no one has mentioned is the matting of the two surfaces. The bottom of the block need to be deadflat also the top area of cross slide. If one surface is smiling, frowning however you look at it. It will translate to the matting surface so now the backside of the cross slide might bow up or down. Idk I just got done bluing every surface on my cross slide and I’ll tell you there was not one surface that blued even 60% every one touch on the corners and raised in the center. Just a thought. Here’s a pic of the bottom of a 14x40 cross slide.
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- Dec 26, 2015
- Messages
- 2,079
I completely agree with JBolt - the T-nuts are the weak link for attaching a solid tool post. The circular T-slots are kinda wimpy as well. I also think you need SOMETHING on the cross slide to act as an anti-rotation stop for the solid tool post block, otherwise a heavy cutting operation is likely to force the solid mount out of axial alignment. Using four bolts at the corners resolves all these issues.
And if you have the skills to machine the solid tool post, and get the registration pins accurately located for the QC holder, you can certainly drill and tap the four holes required in the cross slide. Remove it from the lathe and take it to your mill where you can get accurate position and the holes/taps perfectly vertically aligned.
I noticed on Facebook yesterday that Stefan Gotteswinter is making another solid tool post mount for his new Emco Maximat Super 11 lathe and he's using cast iron. I owned the Maximat V10, and it's compound was not at all rigid, so I'm not surprised this is his first modification to the new lathe. I used a chunk of 1018 from McMaster and have no regrets.
Just this week I removed the solid toolpost from my 1340 to cut a taper - first time I'd had the solid mount off in almost a year. I was machining stainless steel knobs for a new quill feed 3-spoke handle. The knurling operation on that stainless would not have been possible on this machine without the solid tool post IMO - or if it was, it would have taken a lot of passes:
And if you have the skills to machine the solid tool post, and get the registration pins accurately located for the QC holder, you can certainly drill and tap the four holes required in the cross slide. Remove it from the lathe and take it to your mill where you can get accurate position and the holes/taps perfectly vertically aligned.
I noticed on Facebook yesterday that Stefan Gotteswinter is making another solid tool post mount for his new Emco Maximat Super 11 lathe and he's using cast iron. I owned the Maximat V10, and it's compound was not at all rigid, so I'm not surprised this is his first modification to the new lathe. I used a chunk of 1018 from McMaster and have no regrets.
Just this week I removed the solid toolpost from my 1340 to cut a taper - first time I'd had the solid mount off in almost a year. I was machining stainless steel knobs for a new quill feed 3-spoke handle. The knurling operation on that stainless would not have been possible on this machine without the solid tool post IMO - or if it was, it would have taken a lot of passes:
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