OXA QCTP on a Unimat? Trying to make a Christmas gift work for my tiny lathe

[STEMtheMachining]

So my wonderful GF got me a QCTP for my lathe, or at least the information she looked up online said it was for my lathe. Includes 4 cutter holders, a burring bar holder, etc. Very nice and good quality steel it seems.

But the post is (what appears to be) an M10, and my little lathe's t nuts are an M6.

So here's my thought, and this is where I need your help:

I get an M10 equivalent OD rod of tool tool steel, and then turn the lower portion down to M6, and thread that. The M10 rod keeps the tool steel tight in the QCTP, and the small (10 mm or so) section is threaded for an m6 to interface with a t nut. If I then heat treat the tool steel, this should make it hard enough it won't flex and it'll survive the stress of the tool holder.

So my questions.

Am I way off here in my mod? Would that m6 stud be robust enough to withstand the force?

Is there a better way to do this?

Thanks once again.

Update: Upon further inspection, the cap of an m6 cap screw is the diameter of the m10 threaded portion, so another possibility is:

Buying a longer m6 cap screw and turning a sleeve with an m10 OD and an M6 ID, and pressing it into the QCTP to remove the slack. This would allow me to avoid threading tool steel, but instead require me to get the ID/OD dims within 1-2 thousandths.

Is this a better option?





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[Ulma Doctor]

I bought an extremely inexpensive import OXA system for my SL1000, made the modifications and tried to use it.
After many test cuts on multiple materials, i took the OXA off and put it back into the box it came in.
The quality of the inexpensive system was so poor that I went back to the factory toolpost

I hope you have a different experience

 

[STEMtheMachining]

I bought an extremely inexpensive import OXA system for my SL1000, made the modifications and tried to use it.
After many test cuts on multiple materials, i took the OXA off and put it back into the box it came in.
The quality of the inexpensive system was so poor that I went back to the factory toolpost

I hope you have a different experience

This one isn't inexpensive though, and it's much more robust than the little silver QCTP that I suspect you're talking about. (I looked at it as well, even came with some boring bars and carbide inserts, woohoo.)

That and the fact it was a gift is why I'm willing to modify it to make it work.

I'm just curious if either of my mods are
a) practical to solve the problem
b) something a beginner can achieve

Plus I finally found some metal stock, so I'll need some projects.





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[MERLIncMan]

I could be mistaken, but once the post is torqued to spec, there oughtn't to be any concern of flex - it effectively becomes one with the compound. The sleeve seems easiest (but permanentish with a press-fit) while the stud seems most reasonable.

I doubt you need to make it of anything too strong - like I said, torque to spec and the flatness of the tool post against the flatness of the compound does all the load bearing.

I've never seen a Unimat in real life, but it's a cute little thing! How hard do you plan on making her work, that you're concerned about a tool-steel stud for a QCTP?

Not that we need an excuse to make tool steel....

 

[STEMtheMachining]

I could be mistaken, but once the post is torqued to spec, there oughtn't to be any concern of flex - it effectively becomes one with the compound. The sleeve seems easiest (but permanentish with a press-fit) while the stud seems most reasonable.

I doubt you need to make it of anything too strong - like I said, torque to spec and the flatness of the tool post against the flatness of the compound does all the load bearing.

I've never seen a Unimat in real life, but it's a cute little thing! How hard do you plan on making her work, that you're concerned about a tool-steel stud for a QCTP?

Not that we need an excuse to make tool steel....

I don't plan on ever doing heavy work with it, anything more than 20 thou and it gets really bogged down.

Given the relatively light forces involved, would it even need to be a press fit? or would a clearance fit (is that the right term?) be sufficient ?

I'm here to learn, and the Marines gave me thick skin, so if I'm way off base - say so.

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[MERLIncMan]

A Marine!?!?
We used to scoot you guys around to do stuff that the Army was too snooty to do

A looseish bushing sleeve should be absolutely fine - the stability will come mainly from the downforce of the bolt/stud. Good fit, not too much slop.

Is Clearance fit the right term? No idea, but it gets the point across, so that's right enough for Dept of the Navy

I think the tool-steel shoulder-bolt would probably be more fun and a more satisfying experience though. Use some O1, single point thread it, temper it to a nice straw color. Your sweetie will make encouraging-girl noises when you show her the part you made for your new goodie (at least, that's what my sweetie does).

Or, just get a bushing, slap it in there, and get to making chips!

 

[Ulma Doctor]

You don’t necessarily need to use tool steel to make a stud, almost any steel would be sufficient. The difference in modulus of elasticity is negligible for the purpose.

If you were so inclined, you could make a monolithic stud, that has a square end the dimensions of the T-slot, and threaded on the distal end to accept the locknut

 

[STEMtheMachining]

A Marine!?!?
We used to scoot you guys around to do stuff that the Army was too snooty to do

MARINE: My a** Rides In Navy Equipment. (not sure the rules on profanity here)

I was one of those that you knew was on board, but you didn't usually ever see, and we commandeered your Helos in the middle of the night.

Let's leave it at that. Thanks for your service.

A looseish bushing sleeve should be absolutely fine - the stability will come mainly from the downforce of the bolt/stud. Good fit, not too much slop.

Is Clearance fit the right term? No idea, but it gets the point across, so that's right enough for Dept of the Navy

To be fair, no sleeve at all would be close enough for the DOD. They'd just tell us to ignore the slop.

I think the tool-steel shoulder-bolt would probably be more fun and a more satisfying experience though. Use some O1, single point thread it, temper it to a nice straw color. Your sweetie will make encouraging-girl noises when you show her the part you made for your new goodie (at least, that's what my sweetie does).

Or, just get a bushing, slap it in there, and get to making chips!

Unfortunately I live in an area where machinists don't, so finding steel bushings is near impossible. I'll have to make one after I order the steel.

On the plus side, it means I can buy starrett and mitutoyo measuring tools for dirt cheap at the pawn shops. So - win?



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[MERLIncMan]

Unfortunately I live in an area where machinists don't, so finding steel bushings is near impossible. I'll have to make one after I order the steel.

On the plus side, it means I can buy starrett and mitutoyo measuring tools for dirt cheap at the pawn shops. So - win?

Every reason to buy new tools is a good, legitimate, and necessary reason to buy new tools.

House and shop are, however, necessary tools - so if buying Starrett would make you loose those, maybe think a little longer

Bronze bushing from Lowes, Fastenal, or Lightning Bolt would probably be fine.

 

[STEMtheMachining]

You don’t necessarily need to use tool steel to make a stud, almost any steel would be sufficient. The difference in modulus of elasticity is negligible for the purpose.

If you were so inclined, you could make a monolithic stud, that has a square end the dimensions of the T-slot, and threaded on the distal end to accept the locknut

That's an interesting idea. I hadn't considered that. And I can't even wrap my brain how to accomplish that.

M10 rod, threaded, and then use the mill to cut the bottoms in to the square nut dimensions, and then put it back into the lathe and turn down the proximal end to the necessary diameter for the unimats cross slide?

Am I on the right track?

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