…to make a small special part for one of the jewelry hand tools. It is to replace the below broken part. I can furnish additional pictures with measurements or can show you the broken original to measure when I get to DMS.
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Here is a specific link to shoulder screws. Just need the dimensions from the broken one.
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What is this from…?
It’s the screw that attaches the handle on the disk punch. The punch isn’t out of service but you can only tighten or loosen it by hand. The parts are in a small plastic bag in the top drawer under the polishing machine.
Thanks, Walter and Nick, I’ll check there and see if they have the exact size we need.
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I don’t see any that are exact, but probably close enough if we put a sleeve on the shoulder and cut the length of the threads. Do we have a metric tap and die set at DMS someplace?
Yes in the machine shop cabinets but why?
If this is threading into a pre existing hole the shoulder screw you select should match that hole.
Also it is generally a better idea to get a slightly oversized screw and turn the diamiter down than to use a shim.
Yeah, but if I order it oversized and have to turn it down I’d be back to doing machining again. I haven’t trained on the lathe so I’d be filing it by hand chucked up in a drill or something similar. It only holds a handle in place. I’d be pretty comfortable wrapping an old plastic gift card around it just so the handle doesn’t wobble. The threads have to be a pretty precise length as they don’t go into a through-hole and need to thread all the way in. When I cut threads I usually like to clean them with a die.
Would you mind sharing the critical parameters of the part for us? I don’t doubt you did due diligence in searching McMaster, but sometimes other’s searching fu can find items on their site that are hidden in alternate categories. My friend Matt serves this service for me when I can’t find the parts I’m looking for. But, he orders around $1500 in parts from them on a weekly basis. Also, don’t be scared to give them a call if you can’t find the part.
Second, how close of a match have you found? If you have a screw with the proper thread, but the non-threaded shaft is too wide, that is a minor modification to fix. Also cutting the threaded area down so it fits a fixed length hole is minor. But, re-manufacturing the screw from a fully larger version is kind of a waste of time an money.
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@Terrence - if you find a screw with matching thread pitch, but you have to cut down the length - then buy a matching nut. Put the nut on before you cut it to length and then removing the nut will clean up the boogered threads at the end.
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This is a metric screw and I think the threads are M4. The overall length of the screw, head to tip (before breaking) looks to be @ 17 mm. Diameter of the shoulder is 6 mm. Length of the shoulder looks to be @ 7.5 mm. Diameter of the head is 12 mm (I know, probably not crucial). Length of the threaded portion might be around 5.25 mm, but some error due to distortion where threads broke. Diameter of threads 4 mm.
I can supply the original when I come to DMS if needed.
Yeah, if the threads are long enough I usually do that with a die.
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Well,
I pulled your photo into Photoshop and used the ruler included to do some measurements. It looks like the shoulder diameter is 1/4 inch, the shoulder length is a touch longer than 1/4, the Threads look to be 10-24, as I can see about 6 threads and the length of the threaded area is about 1/4 inch from the photo and the width of the threads look to be a #10.
If I’m wrong about the thread pitch and it is a 10-32, then this is a pretty exact match,
Or if it is metric, this is my best guess, but again it kind of looks like a M4 coarse thread rather than a M5 course thread.
Hope this is helpful.
Yeah, it is a metric and I think the threads are M4.
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Thanks for the updated actual measurements, google gave me this option.
https://www.accu.co.uk/en/cost-effective-slotted-shoulder-screws/14261-SFH-M4-6-A1?google_shopping=1&c=2&mkwid=s_dc&pcrid=209497832366&kword=&match=&plid=&gclid=EAIaIQobChMIh4iW7K-g1gIVD41pCh067w3OEAQYBCABEgK0LfD_BwE
It seems super close, are you sure the sholder diameter is 6mm and not 5.5mm? 5.5mm seems to be the norm for the M4 shoulder screw.
Rather then guestimating, I suggest using these two tools (both available in the machine shop) to make accurate measurements of the relevant parts. Use the thread checker to thread into the hole the above piece fits into.
Thanks, Walter. I wasn’t sure that we had a thread checker or where it was located, so I threaded a screw from the hardware drawer into it. M5 was labeled, but the next size I found was not labeled so my best guess was an M4.
If McMaster doesn’t sell the exact part needed, then I suggest contacting the company that made it and order a replacement.