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| Precisely cutting screws and bolts |
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| ieezitin:
Ladies & Gentlemen I seem to remember a little project on here where someone made a fixture for the lathe where he could insert a bolt/screw and part it off very precisely every time. The head of the bolt/screw was inserted into the chuck first leaving the threaded end sticking out, also the head of the bolt hit a stop that was incorporated into the fixture. I have a requirement to make about 25 screws and I need them cut to pretty tight tolerances, but lately I have found I have had this necessity for such a tool anyways so I am prepared to invest some time and make the fixture. If anyone could help either remember the past project or could explain their way of doing this I would appreciate the advice. Many thanks Anthony |
| awemawson:
Start with a piece of hex stock: First it is through drilled and tapped for the screw you want to shorten, then counter drilled and tapped with a thread larger than the head of the screw you are shortening. Thread the target screw into it with the head lost in the counter bore. Screw a grub screw of the larger diameter up against the head Mount in chuck and machine to length |
| black85vette:
--- Quote from: awemawson on December 01, 2012, 10:55:27 AM ---Start with a piece of hex stock: First it is through drilled and tapped for the screw you want to shorten, then counter drilled and tapped with a thread larger than the head of the screw you are shortening. Thread the target screw into it with the head lost in the counter bore. Screw a grub screw of the larger diameter up against the head Mount in chuck and machine to length --- End quote --- Very nice tip! I don't need that much accuracy and tend to just tap a piece of 1/8th inch scrap metal and hold it in a vise. Insert the screw and measure with a digital caliper. Then just cut it off flush with a Dremel using a cut off wheel. The scrap acts to hold the screw and as a heat sink. Once cut you just back the screw out which cleans up the threads. I order almost all my screws in the longest length I can get and then just cut down to size. Only have to stock one screw. |
| joegib:
Suggestions already made will certainly get the job done. The posh device for this job. developed by the watch/clockmakers I believe, is the Lantern Chuck. Here's a nice example of one: http://www.model-engineer.co.uk/forums/postings.asp?th=66771 Joe |
| ieezitin:
Joe Thank you for the link. that looks like a great set up and very well made. strangely enough i am halfway through making a similar fixture out of some old pipe fittings when its finished i will post it. Anthony :wave: |
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