Need advice on making a solid toolpost

[ssdesigner]

Attached is a pic of my setup with the cross slide removed. This is the LMS 5100 lathe. would rather not have to make a new compound slide if possible but I am not sure how to tap into it with the gibs being where they are. I do have the two threaded holes in the swivel disc, but I feel like I would be losing rigidity by using those holes. Lots of YouTube videos on this but of course not one with the setup I have.

Looking for best approach to add a solid tool post / riser. Thanks!

 

[VicHobbyGuy]

I do have the two threaded holes in the swivel disc, but I feel like I would be losing rigidity by using those holes. Lots of YouTube videos on this but of course not one with the setup I have.

I wouldn't worry about using the holes in the swivel disk for attaching a solid riser (a.k.a. 'plinth) in place of the compound slide. I've made a couple of risers (first one Al, ver 2.0 is cast iron) and I followed the common method which is described online (YTube, FB 7x mini lathe group, websites). It's working fine for me, and it's only a matter of 5 minutes (or less) to swap back the compound if I need to cut a taper.
BTW, my lathe is also a Sieg and it looks just like yours.

 

[ssdesigner]

I have seen a lot of positive comments about using cast iron. So you just put a couple of bolts through the cast iron piece that tap into the swivel disc then? And used the existing threaded rod to mount the quick change to?

 

[VicHobbyGuy]

I have seen a lot of positive comments about using cast iron. So you just put a couple of bolts through the cast iron piece that tap into the swivel disc then? And used the existing threaded rod to mount the quick change to?

Yes- whether the aluminum 2-part or the newer cast iron riser, it was just a matter of counterboring some holes for socket head (metric) machine screws for attachment. The counterbores and screws need to be thought through, as you can break that plate if the screws are too long. The riser block also needs a shallow hole for the boss on that rotating plate. BTW, I'd do the marking for the riser attachment holes by transfer punching through the rotating plate.

Also, I couldn't have machined down that cast iron dumbbell I used for the riser very easily on my 7x lathe - I did that on a 10x lathe .
A riser instead of the compound made a really big difference in the performance of my lathe- especially on parting/cutoff operations. The cast iron version is a bit better but the first version I made from separate pieces of aluminum I had on hand was 'the great leap forward'.

I recall making a new threaded post for the toolpost so I don't need to swap it when I install the compound.

 

[ssdesigner]

Thanks for all of that info. Super helpful.

I plan to pick up a 2”x2”x3” chunk and widdle it down on my mill with the fly cutter.

 

[VicHobbyGuy]

I plan to pick up a 2”x2”x3” chunk and widdle it down on my mill with the fly cutter.

That's a smarter plan! Cast iron is dirty stuff to deal with anyway, but starting with a better quality chunk will make it better.
You have more sources for materials at decent prices in the US.

 

[ssdesigner]

Funny enough, a chunk that size with shipping would run me over $50

One cast iron dumbbell shipped from Amazon was $26

 

[VicHobbyGuy]

One cast iron dumbbell shipped from Amazon was $26

You may get "a good one".

 

[homebrewed]

Longtime owner of a 7x12 mini-lathe here. So a couple of things. You mentioned replacing the compound slide to get rid of the swivel disk, but that disk is part of the cross slide. Might be important when it comes to buying the right thing. Also, when the compound is tightened down the swivel disk doesn't come in contact with the bottom of the compound. Think about it. The screws that tighten the compound down ONLY attach to that disk, so if the compound was riding on top of the disk it would freely rotate. A highly undesirable thing, any operation requires a fixed cutter position. So it is a non-issue. Don't worry about it.

Second, I made a solid riser (or plinth, depends on who is talking about it) that fits on the cross slide. Mine is about 2x2 inches. It's good for many purposes, but not ALL purposes. So I didn't get rid of my compound. I didn't add a detent on the bottom of my plinth -- I never found that having fixed orientations of the compound or plinth was all that useful.