Is This a special Screw

R

Rick_B

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I'm talking about the screw that holds the cross feed rack to the bed. On my SB heavy 9 they appear to be flat head allen drive 8-32 X 5/8" machine screws. It also appears that the heads have been ground to sit flush with the bed. I've tried a standard 8-32 flat head machine screw and the head does stick up a tad into the bed. So is there a unique screw I need to find or is it "standard practice " to grind them flush?

Thanks
Rick


 
If you grind much off it, you will lose depth of the socket, and in FH screws, there isn't much to begin with. If only a few thousandths, go for it, but see what impact it will have on the wrench engagement.
 
This is the countersunk ones?

It/they probably is a screw that SB used. On my 10L they were slotted for a flat blade screwdriver, 3-4 of them had the slot boogered up from the screwdriver taking them out and I thought some new countersunk hex drives would look much nicer. But, as you found out, they would stand proud of the bed a few thou. My solution was to use a 82° countersink bit and deepen the hole just enough to make the screw be flush - pretty quick and simple, and the new blackened screws look nice against the shiny bed.

You will find the socket head screw used on the bed are also a SB screw, and replacing with a conventional screw will leave it proud. In this instance it will take whats called a "low cap" socket head to replace those. On the 10L the 3 that held the gear box on and the 2 that held the lead screw rear bearing onto to the bed were 5/16-18 slot head screws and I replaced those too with the 'low cap'
 
Tony - you hit it head on - the screws that are currently in there don't have much of the socket left.

Pacer - I did find a low profile flat head machine screw at Fastenal that I'm going to try.

Thanks
Rick
 
Fillister heads are usually slotted. The Metric equivalent is a "Cheese" head:

ch_head_1bs.jpg


A low head socket cap screw is what Paddy put up, and a Metric one at that. You might look into a button head socket cap screw too, if you want a low profile with a rounded appearance. Also, if the head diameter is a problem, being too large, try to find a 1936 series SHCS. They're not available in many diameters, but the head OD, and the wrench size, is smaller than a 1960 series, which is the standard.


(I worked a second job for 5 years in an industrial fastener distributor)

ch_head_1bs.jpg

ch_head_1bs.jpg
 
thanks guys but the bed is countersunk for a flat head - I don't think I want to or should re-drill for a counterbore?
 
You could probably modify the screw by recutting the angle side of the head. I'd be careful though, sometimes the socket will make that area thin already, so if much needs to be removed, it may be a bad idea. Then your choices are finding another factory screw, or making one from scratch. Measure carefully.
 
they make several different angle heads of bolts dont they?

there is also a low profile torx head that might work for you...
something like this
flat100TorxMS.jpg

flat100TorxMS.jpg
 
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