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Possibility of Using Inch ACME thread in a Metric Threaded Hole

HMH

Plastic
Joined
Apr 9, 2022
Hello everyone, I wanted to get a few opinions on the possibility of using an imperial sized ACME threaded rod in a metric tapped hole before giving up on something. I just got an old 8 inch jaw low profile Palmgren drill press vise at an auction and the acme screw turned out to be pretty badly bent in multiple different directions. I was going to replace it but after searching I only found two suppliers with the M18-2.5 acme thread that I need and they only want to supply it in 1 meter lengths, which would cost me more than the vise is probably worth at this point. The hole for the threaded rod is a little loose so I was wondering if anybody had experience with having to replace a metric rod with an imperial one and if it's feasible. Thanks.
 

52 Ford

Stainless
Joined
May 20, 2021
Hello everyone, I wanted to get a few opinions on the possibility of using an imperial sized ACME threaded rod in a metric tapped hole before giving up on something. I just got an old 8 inch jaw low profile Palmgren drill press vise at an auction and the acme screw turned out to be pretty badly bent in multiple different directions. I was going to replace it but after searching I only found two suppliers with the M18-2.5 acme thread that I need and they only want to supply it in 1 meter lengths, which would cost me more than the vise is probably worth at this point. The hole for the threaded rod is a little loose so I was wondering if anybody had experience with having to replace a metric rod with an imperial one and if it's feasible. Thanks.
Drill out the metric threads and make a threaded insert with SAE ACME and silver solder it in place.

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PDW

Diamond
Joined
Jul 24, 2006
Location
Australia (Hobart)
Hello everyone, I wanted to get a few opinions on the possibility of using an imperial sized ACME threaded rod in a metric tapped hole before giving up on something. I just got an old 8 inch jaw low profile Palmgren drill press vise at an auction and the acme screw turned out to be pretty badly bent in multiple different directions. I was going to replace it but after searching I only found two suppliers with the M18-2.5 acme thread that I need and they only want to supply it in 1 meter lengths, which would cost me more than the vise is probably worth at this point. The hole for the threaded rod is a little loose so I was wondering if anybody had experience with having to replace a metric rod with an imperial one and if it's feasible. Thanks.

No. That's something only the lowest form of hack would do, unless lives depended on getting it working and you were in some 3rd World shit-hole that didn't have the proper item available.

PDW
 

52 Ford

Stainless
Joined
May 20, 2021
No. That's something only the lowest form of hack would do, unless lives depended on getting it working and you were in some 3rd World shit-hole that didn't have the proper item available.

PDW
How do you REALLY feel?

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eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
How do you REALLY feel?

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I dunno. I thought he made it pretty clear...:D

Can't say I disagree.

OP, do you have a lathe? Make a new metric screw? Unless the nut is roached too. Then maybe go with new nut and screw or modify nut and new screw. So many options.
 

52 Ford

Stainless
Joined
May 20, 2021
OP, do you have a lathe?

Good question. In my first post I just assumed he did. No lathe makes a big difference. That M18-2.5 trapezoidal thread is weird.

I didn't see it listed on McMaster.

I think drill press vises are dumb, anyway. Just bolt your drill press down if you're worried about it moving. Don't bother getting a vise to put it in.
 

Limy Sami

Diamond
Joined
Jan 7, 2007
Location
Norfolk, UK
Learn how to screw cut metric threads, .......... despite dire warnings on the internet - they won't turn you gay, give you AIDS or bring down the wrath of god on you
 

thermite

Diamond
Learn how to screw cut metric threads, .......... despite dire warnings on the internet - they won't turn you gay, give you AIDS or bring down the wrath of god on you

True enough as to cutting metric threads.

Just curious, then..

...what WAS it as turned you gay, gave you AIDS, and brought down the wrath of God on yah?

Went to the polls piss-drunk and accidentally voted Tory, maybe?


:D

PS:

If all you have is a clapped-out Palmgren alleged-vice?

Screw screwing with the screw.

Just Cee-clamp over the outside of the POS.

Gar-ron-tee it will hold better.
 

4GSR

Diamond
Joined
Jan 25, 2005
Location
Victoria, Texas, USA
The poster said it was a OLD Palmgren vise. It's going to be Imperial not metric! I have a couple of them and they have inch screws on them. Why do people try to apply metric to old American iron????
 

Limy Sami

Diamond
Joined
Jan 7, 2007
Location
Norfolk, UK
Be very careful, 2.5mm pitch is VERY close to 10 tpi (10.16 TPI to be precise) .......add in (sometimes very liberal) manufacturing tolerances and a bit of wear on both the thread pitch and OD, AND bearing in mind it's both US made and old, you could well be barking up the wrong tree in stating 18 x 2.5.

Just saying ;)
 

Joe Gwinn

Stainless
Joined
Nov 22, 2009
Location
Boston, MA area
Be very careful, 2.5mm pitch is VERY close to 10 tpi (10.16 TPI to be precise) .......add in (sometimes very liberal) manufacturing tolerances and a bit of wear on both the thread pitch and OD, AND bearing in mind it's both US made and old, you could well be barking up the wrong tree in stating 18 x 2.5.

Yeah, 3/4"-10 is very close to 19-2.5 that after some wear they are likely interchangeable.

In any event, a 3/4-10 acme threaded rod ought to either fit or be very close to fitting.

Nor is great precision required.

 

52 Ford

Stainless
Joined
May 20, 2021
If 3/4 does not fit, turn or grind a bit off the crest.
If it will thread in but takes a bit too much force, you can use a bit of lapping compound. Just clean it up with Brakleen afterward.

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HMH

Plastic
Joined
Apr 9, 2022
Sadly neither my wallet nor the small amount of space I have available will permit a lathe, so no lathe for me. Otherwise I would definitely try and turn a new threaded rod myself.
 








 
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