Fitting a thumb safety, steps involved
This was copied from a thread where a member asked how to fit a thumb safety. Although not a step by step descriptions, it gives you some insight on what needs to be done. I hope you find it useful.
OK, let's try and give a description of the steps involved, or actually, let's point out what needs to be done. I am sure that other members will jump in to add their ideas, if I forget something (too early in the morning).
- First of all, I check to make sure that the safety can go on the frame with
no interference. In other words, on a stripped frame, I put the safety on and
make sure that it moves up and down without a problem. I have run on one
incident where the frame clearence notch in the safety was too narrow to allow
full movement.
- After that, I reassemble the pistol and install the sear, disconnector and hammer, but I leave out the grip safety. In that way I can look inside the back of the pistol to see what's happening inside.
- You should now familiarize yourself with the thumb safety's operation. If you look in the shaft of the thumb safety, there are some areas of interest, shown in the picture above.
- If the safety refuses to go in its place, then the sear clearence area needs to be made deeper. File the sear clearence area towards the rear of the safety, not towards the sear engagement area, but at 90 degrees to it.
- Now move the safety to its full downwards position. Check that the hammer is free to move through its travel. If not, then the hammer clearing area needs to be filed down a little.
- With the safety in the frame, try to move the safety up. It probably won't go all the way. Now it's the time to start filing the sear engagement area. Go easy, one stroke too many and your safety is permanently damaged. So when you are sure that the safety can move all the way up in its slide notch, while at the same time fully blocking the sear from moving when you pull the trigger, it's time to stop. Make sure that the trigger doesn't release the hammer with the safety in the up position and you should be good to go.
Did I forget anything?
Put your gun back together and check it.
Originally Posted by socrates
Would you modify or add anything to these instructions if the safety seems
to work ok, passes all function checks, and moves through its whole range of
movement, but is just very "stiff" and hard to operate? I have a new hammer,
sear and disconnector, and I'm wondering if now I need to file the safety a
bit to fit it.
You have to figure out what causes the difficulty of moving the safety. If this is the same safety that worked OK in the pistol before, then most probably the safety is rubbing somewhere internally. Disassemble the pistol and reassemble it without the grip safety, in that way you can see inside the pistol and figure out where the safety is rubbing. I bet you (as Garrettwc said) that the new hammer is touching it somewhere.
quote:
"Note that ordnance specifications allows .005 inch of sear movement during
this test. This holds true for guns with unaltered, ordnance-spec hammer
hooks.(.027-.030 inch and slightly under square, or captive.)"
-1911Tuner
So, would this .005" movement allow a click to occur, or not? I'm thinking no since the tip of the sear shouldn't be clearing the hooks.
I'd rather have the safety completely block the sear. I do not like movement there.
Same here, just a curiosity question. On my original safety, it was not fitted properly from the factory. The new one, not touched, didn't work either, until I threw in a new sear pin (which was a LOT tighter in the frame). That just popped into my head and had me thinking late at night (which is never a good thing).
quote:
Thumb safety not fully engaging into the slide cut
Thanks John for the instructions and the photo. I'm new at this sear/safety stuff and your post cleared up about 99% of my problems.
I have a Charles Daly 1911 and installed the Cylinder & Slide Tactical II hammer/sear/disconnector/sear spring in the pistol and found the thumb safety would not engage the sear.
I found where the safety lug stopped before rotating up and blocking the sear leg. I began stoning the engagement area (several times) and the safety now engages the sear, but the safety still does not rotate up into the slide cut.
After reading your post and some on another site, I see where I must do a bit more stoning.
quote:
Disassemble the pistol and reassemble it without the grip safety, in that
way you can see inside the pistol and figure out where the safety is rubbing.
I bet you (as Garrettwc said) that the new hammer is touching it
somewhere.
In doing this to my CD, I used a "Dental" mirror I bought a Walgreen's. Works great, especially with a bright directed light. You can really get behind the safety and see very well.
Awright- I am trying to fit a new thumb safety to my RIA. I have already replaced the hammer and sear. The safety fits and moves freely in the stripped frame, but will not install with the hammer in place. When I color the end of the thumb safety shaft and the side of the sear with Dykem I can see where they are hitting and why the saftey won't seat. Looking at the end of the shaft, it forms kind of a backward comma; the point of the comma seems to be the engagement area, and this is where the safety is contacting the side of the sear. If I file off the point of the "comma," the safety ought to slide right into place, but I'm not at all sure that's the thing to do. It looks like that point is supposed to be there. Trying to resolve this same issue with my old safety is why I'm installing a new safety now.
John's post above says to file the clearance area back toward the rear of the safety, but that's not where I'm showing contact. The safety currently stands out from the frame about 1/16 of an inch when the hammer is installed.
Like I tell my apprentices at work, "There is no dumb question. Not asking a question is dumb." So here's a really.....uneducated....question- am I correct in deducing that the thumb safety works by blocking the hammer? This might be the key my visualizing how this part should fit; the STI animation doesn't really help in this case.
quote:
am I correct in deducing that the thumb safety works by blocking the
hammer?
The thumb safety blocks the sear. It will only impede the hammer to the extent that the plunger resists its fall.
quote:
am I correct in deducing that the thumb safety works by blocking the
hammer?
Answered this one myself by going to the Tech Issues page and scrolling all the way to the bottom, to the "Trigger Parts" thread. There I found those great cutaway pics, which show the thumb safety shaft impinging upon the sear, locking it against the hammer, thus immobilizing both. The "comma" profile of that particular shaft is much less pointed that that of my safety.
If I'm seeing this correctly, I can go ahead and CAREFULLY dress my thumb safety where the Dykem is rubbed off by the sear; that should allow the safety to seat fully, and operate properly when seated. My earlier efforts were a bit too vigorous, and eliminated any possibility of interaction between the TS and the sear. A new King's #201 Combat Speed Safety costs $29.99 plus tax froms Guns Etc, and is a one hour round trip from home.
The reason the TS wouldn't seat fully seems to be that the hammer needs to be present in order to hold the sear in its operating position. With the hammer out of the pistol, the TS would slide right home and swing through its full range of travel.
I see that Mr. Tuner has posted a reply to my dilemma which seems to confirm that I had indeed stumbled upon the truth. Thank you, sir!
Tonka, the simplest way to fit a thumb safety is to assemble the gun without the grip safety and the plunger assembly. Then, insert the thumb safety and you can see what is interfering with its movement. When you get down to the final fit, use the layout fluid or even a sharpie marker to dress the last bit and get everything workin'.
Wow. That's exactly what I struck upon for a course of action. Uh... this time, that is Once dinner's in the oven I'll get back to work on the pistol.
It is done. I'll give it a "smoke test" tomorrow morning, weather permitting.
I think this is probably the problem with my pistol. Because the safety won't go all the way up when it's in the slide notch. But on a stripped frame. the safety moves up and locks the trigger well. I do believe then that on a stripped frame, the sear is able to engage well in the sear engagement area of the safety. Would it be possible for me to remove by filing the top portion of the safety lever and also a portion of the slide notch (right side) so that the the safety can go a little up and still achieve the same effect as when you file the sear engagement area deeper?
D-will-, you'd do well to read this whole thread, maybe twice, and pay a lot of attention to 1911Tuner's advice. Also look in the smithing/maintanance area, and you'll find a thread about this very subject, with some excellent pics of what you should be seeing. There's also a test regimen to follow when you're ready to see if your fix worked.
The thumb safety operates by blocking the movement of the sear, locking the sear against the hammer. It has NOTHING to do with the trigger; that's the grip safety's job.
I can't stress this enough: BE VERY CAREFUL WHEN YOU REMOVE METAL. The reason I had to fit a safety in the first place was that I installed a new hammer and safety set, and the thumb safety wouldn't seat properly because the stud on the thumb safety was being blocked by the new sear (which didn't have exactly the same profile as the stock sear.) I filed too much, AND in the wrong area, and ended up having to "upgrade" to a $39 King's extended thumb safety. I think I actually like the old GI part better.
If i could do this, you probably can, too. Good luck, don't get too file happy, and be patient.
quote:
Would it be possible for me to remove by filing the top portion of
the safety lever and also a portion of the slide notch(rightside) so that the
the safety can go a little up and still achieve the same effect as when you
file the sear engagement area deeper?
EEEK! NO! PUT THE FILE DOWN AND GO HAVE A NICE GLASS OF MILK!
Sorry, I missed that part earlier. Don't fit any part EXCEPT the thumb safety. Don't file on your sear, frame, or slide. Like I posted before, seek out the wisdom to be found in the gunsmithing section. It's actually pretty simple, but isn't to be rushed into by any means.