C Clamp Replacement Screws

[pamike]

I just acquired some very old large forged C clamps. Google search of the manufacturer doesn't yield any company results. Several have pretty messed up screws. It doesn't appear anyone sells universal replacement screws. All the screws I see are replacements for specific clamps, and they don't list the thread size or pitch. I hate to throw a 12" forged C clamp in the trash due to a bent screw. I suppose I could buy some threaded rod and make the screw but I would much rather just buy a replacement. Any good ideas?

 

[SeisMec]

Acme screw threads are measured by diameter and travel distance per turn.
Here's the relevant McMaster-Carr page.

 

[larry_g]

Make sure of the thread profile you have before ordering ACME threaded rod. There are a few different profiles that at a glance look to be ACME but are not. I wouldn't be surprised if the thread was unique to the clamp.

lg
no neat sig line

 

[davethorik]

Some of the old clamps do use weird threads. I have a Wilton Chicago 4" c-clamp that uses a double-lead square thread. Not gonna find that in mcmaster-carr.

 

[dscheidt]

Some of the old clamps do use weird threads. I have a Wilton Chicago 4" c-clamp that uses a double-lead square thread. Not gonna find that in mcmaster-carr.

Page 1241. "Fast-Travel Precision Acme Lead Screws and Nuts "

 

[larry_g]

Some of the old clamps do use weird threads. I have a Wilton Chicago 4" c-clamp that uses a double-lead square thread. Not gonna find that in mcmaster-carr.

Page 1241. "Fast-Travel Precision Acme Lead Screws and Nuts "

ACME is not a square thread.

lg
no neat sig line

 

[davethorik]

Page 1241. "Fast-Travel Precision Acme Lead Screws and Nuts "

While i get your point, i dont think that is square thread. It might work, though! I have to go dig that Wilton out and measure it. However the prices for minimum kind of preclude what would be a cheap fix for old clamps. And that is the smallest size.

 

[pamike]

Yes, I understand your points. But no one actually addressed my original question...everyone is just arguing about what thread it is and where to go it...
I am not looking for threaded rod, I am looking for complete screws with the handle hole etc...

 

[larry_g]

I just acquired some very old large forged C clamps. Google search of the manufacturer doesn't yield any company results. Several have pretty messed up screws. It doesn't appear anyone sells universal replacement screws. All the screws I see are replacements for specific clamps, and they don't list the thread size or pitch. I hate to throw a 12" forged C clamp in the trash due to a bent screw. I suppose I could buy some threaded rod and make the screw but I would much rather just buy a replacement. Any good ideas?

Yes, I understand your points. But no one actually addressed my original question...everyone is just arguing about what thread it is and where to go it...
I am not looking for threaded rod, I am looking for complete screws with the handle hole etc...

We can only do some educated guessing here as you have yet to give up the manufacture and/or the thread form, size, and pitch of what your looking for. Kinda like asking for leads to a wheel for a car without any size or brand information given.

We are not arguing, we are giving you information that you need to know, and give to the group, to narrow down your hunt.

lg
no neat sig line

 

[crguy]

Yes, I understand your points. But no one actually addressed my original question...everyone is just arguing about what thread it is and where to go it...
I am not looking for threaded rod, I am looking for complete screws with the handle hole etc...

A new screw with handle hole, etc. will cost you more than another good used clamp would. Just face it and move on.

 

[pamike]

We can only do some educated guessing here as you have yet to give up the manufacture and/or the thread form, size, and pitch of what your looking for. Kinda like asking for leads to a wheel for a car without any size or brand information given.

We are not arguing, we are giving you information that you need to know, and give to the group, to narrow down your hunt.

lg
no neat sig line

Samson brand, 12", 3/4-6 acme thread.

 

[pamike]

A new screw with handle hole, etc. will cost you more than another good used clamp would. Just face it and move on.

I didnt ask about price, I asked for a source. A FORGED 12" C Clamp on 1960's vintage that is heavy and quality is fairly expensive. Combine that with the fact that I just dont like to waste things, and I would gladly pay for a quality replacement screw.

 

[Shadowdog500]

If the screw is bent I bet a dollar that the frame is probably tweaked a little as well.
I had an old c-clamp with a tweaked frame and tossed it in the metal scrap bin after fussing with it for a while.

 

[The Cobbler]

if you watch some you tube videos on shaft straightening, you can probably get that back to usable condition
Both Keith Fenner & Keith Rucker have videos on the topic

 

[larry_g]

https://www.zoro.com/zoro-select-ac...teel-0750x36-24304/i/G1456664/#specifications

Above is a 3' piece of 3/4-6 acme screw. Get a couple of matching nuts. Weld the nut on the one end and use a wrench to tighten the screw. Grind or turn the other end to accept your existing pad, or order new pads from the usual suspects.

Second would be to get on the phone to a couple of current c-clamp manufactures and have them give you the part number for what meets your specs.

Third, maybe ask the members if they have a modern clamp with a 3/4-6 acme that has a manufacture name on it that you can call. I looked through my stock of clamps and found none with the 3/4-6 thread. I did find a bunch with non acme threads though.

lg
no neat sig line