The inevitable has happened: replacement jaw screws

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Established Member
7 Apr 2020
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Somewhere on my floor lurks an SC4 jaw screw; after an hour of cursing on my hands and knees, and not in a fun way, it's clear the only way it's going to turn up is by ordering a replacement. No problem I thought, these are obviously bog standard machine screws. Except they aren't. The heads have a smaller diameter than standard DIN 7991 machine screws.

I've also bought a set of Charnwood long nose jaws and these need an slightly smaller head still, about 9.8mm.

Is there a standard name or size for these things? I can find replacement sets easily enough on Record Power's website, etc, but I feel like £5-6 for eight screws seems excessive.
I got stung with this on my record rp2000 chuck. Luckily I haven't lost one but have rounded a few heads. Postage is another fiver on top.

I haven't purchased yet but am nervous changing jaws over. I have another chuck that I prefer but have 70£ tied up in scrap with this until I get new screws.
If you buy standard HT set screws from evil bay or Amazon you need only to put them in your battery drill and spin the heads onto a moving grinding wheel - the amount that needs to be removed from the circumference is negligible. Wise to stick to high tensile, though.
A strong magnet on a stick might find it,and will certainly help your knees. You will also find all sorts of other things you didn't know you'd lost, as well.

Before you invest too much time, you might want to make sure that the thing in question you are hunting for is actually magnetic.

I use an old speaker core from a sub-woofer - it still looks like a speaker,but it does the job. You know when you drop a box of screws...
Thanks for highlighting this issue. I’ve got a RP SC3 and presumed they were ordinary machine screws. I think I’ll be being a bit more careful from now on.
Hope you find a cheaper solution
2s up for the magnet.

When I manage to drop a screw changing the O'Donnell jaws on my C10 Axy chuck it always falls into the large pile of shavings under the lathe. I have tried sifting through that pile a number of times repeating "GOLLY GOSH" several times until I tried the same with a rare earth magnet. Since then it takes me just a few seconds to find it.

On a stick you could find all sorts
Magnet on a stick doesn't sound like a totally daft idea! I've given up on finding the original, but in future when I feel the need to change jaws I think taking the chuck off and doing it on a tray might be sensible. In the meantime I can't (easily) find high tensile screws the right size so I've bitten the bullet and order the Charnwood screws that should do for both.
I also have a rare earth magnet on a stick about 18 inches long, its kept, until needed stuck underneath my bandsaw table. I bought a few with the hole in the middle When I let 2 collide with each other I now have 4
Before you use your magnet put a small bag or bit of tape over it. Makes it much easier to remove all the rubbish that it inevitably picks up.
Chuck manufacturer costs for machine screws is outrageous. I have used the following website to order both countersunk, and cap head machine screws, you can also get Torx head if you prefer as less rounding problems than Allen keys ... crews.html
As already suggested, if the head is too large put in a drill and spin against bench grinder.

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