Solid Tool Post Riser for my 13"x40" lathe

[ChrisAttebery]

In retrospect how does the single point cutting option look to you now?

Magical!

Actually if I had the tool it wouldn’t have been too bad. Especially with the tap to chase the threads.

 

[ChrisAttebery]

Over an inch of engagement with a 5/8 x 11 thread? You'll be able to pick the lathe up off the floor with your whole family sitting on the bed!

I believe in TLAR engineering. That Looks About Right.

 

[Buffalo21]

I go by the “as long as the thread depth/engagement is more than one bolt diameter, your okay” theory

 

[Bamban]

Most of the folks on the forum that have added solid plinths to their lathes report improvements in rigidity, though I suspect
the smaller, lighter machines benefit the most. I found benefits in greater DOC, less chatter and better parting. Because
it's smaller than the compound, it's nicer to work around and there's no danger of bumping the handle and changing
tool position.

It looks like you're doing a great job on yours. Looking forward to seeing the finished product.

You are right, my 9x20 works great with the solid mounts. I use the backside QCTP dedicated for parting. To mount the plates I just modified 1/4x20 carriage bolts for t-nuts.

 

[mattthemuppet2]

This was just a Irwin Hansen hand tap from Ace HW. As I was staining to get it to cut I kept thinking that a spiral point tap probably would have been a good purchase. I probably could have gone up one drill size, but I was lucky to find the 17/32" drill as it was. They didn't have a great selection. It should have 12 threads worth of engagement. I hope that will be enough to keep it from slipping. ;^)

well, a 5/8-11 tap isn't exactly common use so it's hard to justify big $ for one use, but keep your eye open for deals on Amazon. It's hard to get across how much better machine taps (spiral point and spiral flute) are than big box hand taps.

 

[ChrisAttebery]

The compound mounting bolts on my lathe drop out from the bottom so they will have to stay in place when I use the riser block. Yesterday I drilled two 1/2" holes in the bottom of the block on my CNC mill to clear those bolts. Then I was finally able to put the block in place on the cross slide. I indicated the block parallel with the cross slide and clamped it in place. I had only drilled the mounting holes in the block to 5/16" at this point so I used a hand drill with a 5/16" drill bit to start drilling the mounting holes into the cross slide. I removed the cross slide and finished drilling the holes on my drill press. I forgot what a pleasure cast iron is to drill. I hand tapped the holes to 3/8-16 and mounted the block. It's a little high so I'll have to face about .012" off the top.

 

[brino]

That looks very solid.

Thanks for bringing us along for the build!
I can't wait for some results....

-brino

 

[ChrisAttebery]

Last night I fly cut the top of riser until it matched the height of the compound. Then I machined an alignment plate out of 3/16" HRS. This morning I blued the alignment plate and installed it. I took some test cuts on a piece of 1" 1018 CRS last night. I did a couple passes at .060" DOC, .006" IPR and 460 RPM and then cut off a couple slices with my carbide insert cut off blade. It's definitely stiffer than before. The cut off tool would chatter in steel. Now it just plows along.

 

[ChrisAttebery]

I weighed the riser last night. It's 15 lbs, 12 oz. So I wound up removing 19lbs of steel from the block.

 

[brino]

It's definitely stiffer than before. The cut off tool would chatter in steel. Now it just plows along.

That sounds like success!
Congratulations, on a great build.

-brino