View Full Version : 1911 thumb safety, how to reduce pin size ?
August 23, 2005, 04:28 AM
I just picked up an extended thumb safety, made by one of the higher end 1911 parts mfrs.
The top part of the pin is tapered slightly and needs to be slightly smaller (and untapered) to fit the frame. It appears to be tapered about .003 from tip to the bottom. The tip fits perfectly - about half way, then the taper is larger than the hole in the frame.
How do I turn the pin down or remove just enough for it to fit properly ? I have bought these before and they slipped right in.
I have the Kuhnhausen books and the pin is within tolerance - the low end at the tip, the high end at the base.
I thought about chucking it up in a drill press and using a fine grit paper to slowly reduce it, but I'm not sure that's the proper way to do this.
Can someone tell me the best approach to this ?
Thanks for the feedback
August 23, 2005, 10:05 AM
If you wanted to avoid returning the safety for a replacement, I'd probably use the emory paper and a vise to "shoe shine" the base of the pin. Just go slow and check for even roundness often.
August 23, 2005, 10:46 AM
Send it back
August 24, 2005, 10:56 PM
If the pin is within spec, your frame hole isn't, so a replacement safety may not fit either. If you haven't done so already, measure the pin with a micrometer (the kind that looks like a C-clamp; a caliper isn't accurate enough). Dont forget to wipe it off and close it to zero to see what to subtract from your final reading?
When you know what the pin diameter really is and have verified it is really in spec, go to MSC (http://www1.mscdirect.com/cgi/nnsrhm) and get a straight flute, straight shank, HSS chucking reamer. If you run the site's quick search for chucking reamers you will get a list with a refinement menu at the top and by entering flute and shank styles, the size list becomes active for the type. This style is available in increments of thousandths and some half thousandth increments. Try to get one that equals the size of the pin at its wide point or is up to a half thousandth larger. Ream only the left side hole, using lots of oil and turning very slowly and with a light touch to let the reamer guide itself in, then get out quickly. Using reamers properly is something of an art that would take a magazine article to describe, but you aren't needing to hold ten thousandths here, so you should be OK. Use a drill press at its lowest speed if one is available to help keep the reamer perpendicular.
After widening the hole, if necessary, lightly shoe-polish the pin with fine wet/dry paper around the base until it just turns freely.
August 25, 2005, 12:41 PM
Or a rat tail file.
August 25, 2005, 01:12 PM
I'm not a gunsmith, but I have done a few. I think I would rather fit a safety to a frame rather than a frame to a safety.
We have established that the pin on the safety has a taper. How close is it? Can you fit it in the holes with nothing else in the frame? Even if it's overly snug? If so, I think what I would do is put some oil on the pin, and work it back and forth until it fits. This may still enlarge the frame hole, but I doubt it. Insert it with the safety facing backwards and upside down to give yourself a good arc to work it through. Go slowly, taking off a little bit at a time, and use oil.
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