New 1911 project: Lap or file slide to frame?

[scott.cr]

Hi all, I'm building a 1911 and the foundation is an SW1911 frame and an STI slide.

S&W's radius for the grip safety is like .170" -- unusual eh? So facing the prospect of keeping the ugly OEM grip safety caused me to look for alternatives and I ended up shipping the frame to EGW to have them weld up the tangs so I can use .250" grip safeties. I'll say that the weld job itself was a bit toothpasty, but after working it with a file it looks perfect. I also had them do a 30 LPI checker job on the frontstrap. It's gorgeous and the price not too bad. Turnaround for the work was about two weeks.

ANYWAY. I'm looking for suggestions on fitting the STI slide to the frame. It's not near close to fitting. I was considering purchasing a slide/frame file from Brownells and doing all the fitting by hand filing. Does this sound like a foolish idea compared to lapping? I'm good with a file and can make metals look like they went under a flycutter.

What about intermixing the two faiths? (Roughing it with a file and finishing with lapping, for instance.) Is there anything bad about either way? I've heard a few 'smiths sneer at the lapping method, but can't quite figure out why.

 

[1911Tuner]

Fitting

Howdy Scott,

As a rule, if the slide will start onto the frame, you can lap it. If it won't, it's best to start filing. I wouldn't rough-fit it with the files though. First, determine where you need to file and go S-L-O-W. Use the files as though you didn't have lapping compound, and use the lap for the final fit. When you get it to the point that the slide will go onto the frame about a third of the way with some effort, go to the lapping compound. I start with 800-grit for one on-off pass. Rinse well. Dribble some oil into the rails on top of the lap to keep it from galling. Go to 5 micron lap for one pass and rinse. Go to straight J&B Bore Cleaner for a few passes...until it starts to glide. Rinse. Mix a medium-thick slurry of J&B with CLP Breakfree or any other teflon-based oil, and move the slide until it gets smooth. Might take 50 passes...Might take 250.
Every so often bias the pressure for 2-3 strokes...first to one side, then the other...Then up, then down...with the slurry only.

When using the lapping compounds...while the slide is still a tight fit, be careful on the rearward stroke so that you don't damage the fronts of the frame rails should it suddenly break loose and go full travel. If it gets stuck, use a piece of 2X4 to knock it back off with a piece of heavy cloth covering the slide. Towel material will do. Don't knock it further on once it sticks hard.
Wipe the fronts of the frame rails each time the slide comes off, or you could cut them undersized before the rear area comes to size. Not necessary with the slurry.

Don't force the slide any further onto the frame than bumping with the heel of your hand. Each pass will push it a little further. Even if you can only advance it a tenth of an inch at a time, it's better than sticking it hard and galling the rails trying to get it back off.

Finish it with oil until the slide will make full, unhindered travel by tilting the frame up and down at 45 degree angles. Might take several hundred strokes.

If you're very good with the files, and very patient, you can bring it into dimension to the point that you'll only need straight J&B, followed by the slurry and straight oil. Takes time though...

Luck!

 

[WarMachine]

^^^The above is the reason God created gunsmiths

I just KNOW that I would screw-up trying to properly fit most anything to my 1911. I really envy the skill some of you guys possess...

 

[ZenMasterJG]

Seriously. its practically voodoo.

I'd certainly have a better chance fitting it by dancing naked around it and slaughtering a couple chickens....

 

[BluesBear]

Just remember to keep the Chicken Blood to CLP ratio less than 1 part blood to 5 parts CLP. 1 to 8 is better.

And you need to kep it refrigerated until use so it doesn't get too thick and sticky.


Chicken beaks when ground extremely fine can be added one peck, er, um, I mean, one part beaks to four parts lapping compound.

 

[1911Tuner]

Voodoo

Nahhhh. It don't take chicken blood or dancin' around. Patience and time...
The right tools, and a little elbow grease is all.