Tommy bar material?

[fcs]

I need to make tommy bars for my small set of machinist clamps, vee blocks etc. I tried W1 steel rod, but it’s too soft, at least without hardening. What should I use instead? Something I can just cut to length.

 

[Ulma Doctor]

if you have a propane torch, you can heat the W1 to red hot and hold it there for a minute or 2 and plunge the W1 into water
this will harden the W1
you'll need to temper the W1 by slowly reheating to around 350 to 400°F (a pale straw color)
the W1 will be hard, but tough at this point

another possibility is 1144SP shafting material, it is quite tough in the condition supplied

 

[MrWhoopee]

I assume you are bending the tommy bars, what diameter are they? ETD-150 or 4140QT (pre-hardened, sometimes designated 4140HT or 4140PH) are about the hardest you will find off the shelf, but (IIRC) are not available in sizes under 1/2". Another possibility is Thomson 60 Case shaft, which must be cut with an abrasive cut-off wheel. Flame hardening the W1 that you have may be the best solution. That and shortening the bars.

 

[NC Rick]

+1 on 4140 ph! Wonderful to machine and very tough if not super hard. Thompson shaft is very hard outside and for me a problem to work with if it isn’t going to stay a shaft. If you are going to heat treat it yourself without an oven 1095 is about as hard as it can be (similar to drill rod).

 

[Winegrower]

What’s a Tommy bar?

 

[Illinoyance]

I use the shank of an old screwdriver. Sometimes the whole screwdriver.

 

[fcs]

These are all small, inexpensive Asian clamps. (I make small things.) The holes measure a little under 0.120 so I suppose they are 3mm. Maybe I will try hardening the rod I have but if that doesn’t go smoothly I may just order some 3mm M2 drill blanks from McMaster. Unless there’s a reason that those won’t work. I’m not tightening anything with high torque.

M-C has 4140 rod but not in sizes under 0.250

 

[kd4gij]

I just use allen wrench to tighten small clamps like that.

 

[fcs]

I just use allen wrench to tighten small clamps like that.

Good idea. I’ve got a box of orphaned Allen’s. Just keep a few with the clamps.

 

[NC Rick]

FWIW I make some little formed tools which preform a similar task to what you are looking for. I need to form the end in a bending jig and found W1 to be quite a bit less mailable than O1 as we get the 0.257” rods delivered from McMaster carr. The W1 is stiffer and snaps before we can put about a 20 degree bend in them with about a 2d. Bend radius. I’m not sure if drill blanks will be a lot stronger but they won’t bend!