Possibility of Using Inch ACME thread in a Metric Threaded Hole

[HMH]

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]

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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[john.k]

Spend some time straightening the screw....it will work again OK

 

[PDW]

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]

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]

How do you REALLY feel?

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

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]

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.

 

[johansen]

you can probably buy 3/4-10 tpi acme thread and then take a portion of it and cut slits in the acme thread to make a tap.. and run it through the nut.

or just buy a nut for 7$
3/4 - 10 Right Hand Acme Lead Screws & Nuts for Power Transmission - Roton Products, Inc.

 

[Limy Sami]

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

 

[Glock34]

How do you REALLY feel?

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He probably feels like he's in MY shop. LOL!!!

 

[jim rozen]

When did Palmgren change over to metric??

Mine's good 'ol usa murrican inches.

 

[4GSR]

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]

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

 

[52 Ford]

add in (sometimes very liberal) manufacturing tolerances

Careful! Gotta keep politics out of it - Liable to end up like Milland and EG.



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[Joe Gwinn]

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.

 

[johansen]

If 3/4 does not fit, turn or grind a bit off the crest.

 

[Illinoyance]

Unless it is an OLD Palmgren vise it is probably not worth your time to fix it.

 

[52 Ford]

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]

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.

 

[HMH]

I mic-ed several spots on the screw and was consistently getting ~0.69-ish, which translates to about 17.5 mm according to the quick calculator on google. I say "old" palmgren vise because it's been fairly well beat to death but I'm not sure how old it really is. The bolts holding the jaws in were also in metric as well as the set screw holding the acme thread to the moving jaw.