5/16-18 machine screw with small head

pipsters · Sep 27, 2012

My vise resto I am doing (and slowly giving up on day by day) needs a 5/16"-18 roughly 3/4" long flat headed machine screw to hold the jaws.

The problem is all of them that I can find have a .59" head diameter.

The max I need to have is roughly .42" +/- on the head.

I don't own a lathe so I can't turn them down.

Just wondering what are my options...or is this thing scrap...(it kinda already is but I wanted a beater vise, but it still needs jaws).

Conor · Sep 27, 2012

drill press and file?

larry_g · Sep 28, 2012

http://www.fairburyfastener.com/xdims_shcs_low.htm

Will a lohead shcs work for you. Standard hardware at betters stores.

lg
no neat sig line

DandDMachine · Sep 28, 2012

Put the screws of the thread in a drill and spin the head against a bench grinder wheel. Give it gentle pressure and let the stone do the work. Its not perfect but will be pretty close to concentric if your careful. I have done this a few times in a pinch.

2oolhound · Sep 28, 2012

I've done much worse with just a file. Lock 2 nuts on it and secure it in a vice and get at er. You'll be done before you could have gotten to the hardware store.

pipsters · Sep 28, 2012

DandDMachine said:
Put the screws of the thread in a drill and spin the head against a bench grinder wheel. Give it gentle pressure and let the stone do the work. Its not perfect but will be pretty close to concentric if your careful. I have done this a few times in a pinch.

I was trying to figure out a how to do this...thank you...that is spot on and makes total sense. I couldn't come up with a way to keep the outside of the screw nice and round but you have it.

pipsters · Sep 28, 2012

larry_g said:
http://www.fairburyfastener.com/xdims_shcs_low.htm

Will a lohead shcs work for you. Standard hardware at betters stores.

lg
no neat sig line

Unfortunately no, I looked at those but I need the taper, actually all the tapers I've found are really too dramatic but I'm gonna have to make it work.

Outlawmws · Sep 28, 2012

Is there meat in the jaw to countersink to the larger size? You said its a beater, so it's not like it has to be factory spec.

pipsters · Sep 28, 2012

Outlawmws said:
Is there meat in the jaw to countersink to the larger size? You said its a beater, so it's not like it has to be factory spec.

Yeah there might be a little bit to drill. I ordered 6 from Fastenal for a total of around $9 so we'll see about it when they get here.

Outlawmws · Sep 28, 2012

The other thing that can be done if you are short of thickness for the screw head depth in the jaw facing ,is to get it the minimum needed to clear the screw head, and then countersink the main jaw just a little so there is a slight step between the jaw counter sink and the clearance for the screw. You want the pressure on the attached jaw face, not the main jaw. It just needs a little.

DynoDale · Sep 28, 2012

This is probably what you're looking for:
Making some "special" vise jaw screws.

pipsters · Oct 1, 2012

Ok I used my bench grinder and wound down the screws I got from Fastenal. Worked pretty well once I got t hang of it. I now have 4 new screws with P4 heads on them.

In the one pic you can see the old screw I drilled out, the new unabused one, and one that I ground down to fit.

5/16-18 machine screw with small head

pipsters

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Conor

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pipsters

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pipsters

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