Slide machining recommendation please

R

redlightrich

New member
Hello all, I have purchased this slide for my Kimber, and the slide channel is a few thousandth's too small. My frame in the mating area is .07525, and this slide's measurement is .07525 ( the display changed when I moved my hand for the pix). Please note, my measuring device rounds to the closest half "tenth" so, there is the possibility of 6 tenths error. The slide does start and will go on approximately 3/4 of an inch by wiggling it before I become uncomfortable forcing it more.

Removing metal from the frame rail is not a good option for me, as I already have 2 slides that fit the frame. If I remove metal from the frame, I will be introducing unnecessary clearance with the existing slides.

Does anyone have a suggestion as to who can handle this type of machining process? I am not opposed to buying tools and working it by hand if that is possible. My guess is I need to remove approximately .001 to .0015 from each side, for a total of .003

The factory slide is fit a little on the loose side, and it measures .0759 in the same area. My second slide, which fits better ( but still not perfect) measures 0758.

Ideally, I can open this slide to .0756 or .0757

Any referral or recommendation will be greatly appreciated.

Thank you

Rich
 

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It's not a machining process, fitting slide to frame- it's a somewhat tedious, hand-labor process of using lapping compound, or perhaps stones in the beginning if too much material needs to be removed for efficient lapping.

I'm not a pistolsmith- so I won't go beyond that as like many operations there are different methods and materials used, and specific recommendations would also relate to the level of precision desired here.

Just google "1911 slide lapping" on the web or YouTube- or hopefully a pistolsmith here will chime in. If you're not comfortable with D.I.Y., look for a local pistolsmith and have him do it for you.
 
"...hand-labor process of using lapping compound or perhaps stones..." Stones for a few thou. Lapping is more about making stuff flat and smooth. Doesn't remove metal by the thou.
.0756 or .0757 may or may not be enough. It's really a trial and error thing.
"...If you're not comfortable with D.I.Y..." Needed to be bigger. snicker.
 
DON'T lap the slide/frame.
You can use stones, diamond files, or even wet/dry sandpaper to remove metal inside the slide.
See if you can measure the inside of the frame rail cuts in the slide. If they are too small, you will have to remove metal from the frame rails, too.
 
I assume you are looking at the groove depth of the slide, and not the width of the groove.

If you have a mill and the proper width slot cutter (0.101"), with a diameter small enough to fit inside the slide, you can probably just touch off on each slide groove, and take 0.001" from each to get it to fit. A close sliding fit, would be about 0.002" wider the frame rail dimension.

If not, you might use a joint file, (see link below), a type of needle file, that will fit within the grooves of the slide. They come in thicknesses from 0.051" to 0.047". and are side cutting only. You'll probably want something like a #0 or #2 cut, or you'll be weeks taking out any metal.

http://www.ottofrei.com/Store/Glardon-Vallorbe-Swiss-Made-Needle-Files/Glardon-Vallorbe-Round-Edge-Needle-Files-LA2417.html

Another way, would be to machine a piece of flat under 0.1", so it is thin enough to wrap a piece of grit paper around, and use that to work out the groove depth. Don't be afraid to use a coarse enough grit, until you get it fitting, then polish/lap it. The only problem with this, is allowing the paper to hit the sides of the groove, since you only want to deepen it.

You can get a pillar needle file, but they will cut on all sides, though they don't have a slightly rounded edge profile.
 
Note that the OP does not want to modify the frame because he has other slides that are fitted to it, so the work must be done on the sldie.

For a job like that, he might need to buy a square or rectangular cut file that is too wide and make it safe-side by simply grinding off the sides so it cuts only on the bottom. Of course that destroys the file for anything but another job of the same kind, but it works.

Jim
 
I have another suggestion.

A)Lapping is generally the process of using a softer metal to drive a grit to cut the harder metal.
B) The grit size will determine the clearance you will end up with. For a ballpark estimate,you may get nearly .001 out od 800 grit,and near .002 from 500 grit..Note,I daid "ballpark"The lap size will also play a part in what you are doing.

C) You have only looked at width.I suggest gage pins to check your height measurement.You do not want that sloppy,either.

You need a coulple,maybe three brass blades.Start with one clearance .001 or less through your slide.A dragging slip fit.

Have one more a line to line,snug fit.

For height? You may want .002 clearance or .003,if you do not want to cut.

You will want to figure out some means to Stroke it,a simple handle.

Use the slip fit,smallest blade,and say,800 grit aluminum oxide lapping paste first. Stroke till its free,clean up,try your fit.
Too tight? Go to 500 grit.Your lap will cut a little bigger.

Cleanup,and try.

More? use your next tighter brass blade,and back to fine grit.

That's how I would do it.

Once you make the blades,probably very little time cutting.


A very good machinist can do amazing things with the sort of "vintage" machinery likely to be in a home shop.But working less than .001 on a 30 year old Bridgeport someone picked up for $2500 is not without risk.

Put a ground parallel in your vise and a test indicator in your spindle.

Zero your indicator on the parallel as if you were squaring the vise.
Travel it x + and X - .What does your indicator tell you? Is it stuck on zero?

Now,repeat with the contact point of your indicator on the top of the parallel.

You will learn about your machine
 
Thank you for all the ideas. No, I can't simply lap this in, as that will affect the frame. Of all the ideas, I think the one that will work for me best is the "blades" in incrementally larger sizes. I can use the "blades" with a coarse compound, until it runs thru smoothly, then I can use the next size blade.

My guess is I will need 3 or 4 blades in .001 increments.

Now the trick is to find someone to machine me the "blades", if a mistake is made machining the blade, there is no problem. The slide however can easily be ruined by trying to machine such a small amount.

I also liked the idea of machining a file so it only cuts on it's edge. Either way, I see a machine shop in my future!!!

I will avoid the temptation to try something that will not work well. I don't need this slide right away, and I don't want to compromise the gun frame. I will take my time and do it right.

Thank you again

Rich
 
One more thing to consider is corner conditions.
They can fool you.Any cutter used to make an inside corner,such as you have in the slide rails and frame,will leave a corner condition.Dead sharp corners don't workout on cutters.I deally,your cutter will leave the radius ground on the cutter.It might be .003 or so,more or less.

Or,the cutter may show wear,which will effect the form of the cut.

Remember,inside corners are naturally radiused or imperfect.

Outside corners are naturally sharp,or burred.

So,even if you have the correct dimensions on two parts to fit together,you can have interference at the corners.

The inside corner radius is a good thing.Leave it.You may have to lightly chamfer the outside corners so they do not interfere with the inside corner radii
 
Thank you for that information. I am now searching for a machine shop to make my "blades" which I will use to fit the slide. I am in no urgent rush, but I hate leaving things sit around.

I don't think the blades are difficult to make with 3 simple cuts

Thank you

Rich
 
These are designed for removing vertical slide play- but perhaps might be useful in this application if you can get an accurate measurement of slide groove height. HiBC mentioned gage pins which would be ideal, but you're not going to have them.

http://www.brownells.com/gunsmith-t...de-tools/1911-slide-fitting-bars-prod842.aspx

Looking at your electronic calipers, I would enter a note of caution.
If they're a very inexpensive import- they will often not have an accurate measurement. Ok for looser tolerances, and sometimes "repeatability", but for actual accuracy not so much. I once put a HF caliper up against my Mit and it was off by ten thousandths.
 
I did see those Brownell's tools. I have considered buying the correct one, cutting it down and use it to lap the slide.

I will keep searching until I find exactly what I need. I don't need to rush, and I don't want to harm the slide or render it useless.

I will get this resolved. I always seem to find a way!

Keep the ideas coming. Something is bound to work!!

Thank you

Rich
 
Depends on the machineshop,but
1) tape over your slide to protect it from handling damage with blue painter tape
2) Take the slide to the machine shop.Disassembled,take the frame,too.
3) Explain you want some brass laps,what you are doing.
I would think between 2 and 4 inches long..maybe a 10-32 hole for a knob attachment?

Let them help you measure,just take the frame home.They need an FFL to keep it overnight.
If you want no cut on the height,ask for about .005 total,.0025 per side,clearance on the height.

Ask for blade one to be about .001 to .0015 total width clearance.Easy slip fit,but will cut some with 800 grit.

Ask for blade two,line to line fit.Maybe two of those.If you think you need it,maybe a .001 tight,
But really,this is LAPPING,and you don't lap out .002 or .003.
You lap a line to line or slightly tight fit,cutting off the high spots.

If the slide starts on,then gets stuck,you can probably lap it fine.

Start by putting about a .003 or so chamfer on all outside corners that run against an inside corner.

Then work finer grit to coarser..backwards,because bigger rocks cut more clearance.

Whether the grease in the compound,kerosene,olive oil,I don't care,dont let it cut dry

On the Brownell's slide fitting bars..nice idea,good thinking!.

The issue,think microscopic.See what you cannot see.Brass is used because it is soft.The grit particles embed in the brass.The brass is a matrix.The brass drives the grit.There is far less friction/cutting on the brass.The cutting will be on the steel.

So,if you get your hardened steel bars,the grit will embed in your slide,and cut the bar!.
 
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I had a Peterson, I had a QuickWay and I had a grinder that looked like a drill press, I wore that one out. I took it apart thinking I would tighten it up and then I got over the it.

The last grinder I worked on was attached to a lathe. I should have suspected something was definitely wrong when I found all of the ground connectors missing.

F. Guffey
 
Rich,

I've built a lot of custom 1911 pistols many from slides and frames that were gunsmith fit units.
They had to be machined to fit but I never machined the slide to go all the way on the frame because I wanted to hand lap them.
I used 38-900 and 38-1200 mixed with cutting oil for the lapping process and when I finished, the slides would slide on the frame fore and aft under their own weight as if they were on ball bearings.

Without taking measurements for myself of your slide and frame I can't say for sure, but I believe your concerns of your other slides being to loose after lapping the new slide may be something not to fret over.
If your concern is mechanical accuracy don't be to concerned, mechanical accuracy from slide to frame fit is a much smaller contributor to accuracy then most people believe.

Best Regards
Bob Hunter
 
Thank you Hunter, I believe I need .003 more clearance. One of my 1911 frames is exactly .0045 smaller than the frame I want to use, and the slide goes on that with clearance. In studying the relation of the parts, I may be able to remove .0015 from each side of the frame rails without compromising the accuracy when the gun is set up as a .45, however, I also often use it as a .22, which is a favorite caliber of mine. My fear is not that the .45 accuracy is affected as much as I worry about the 22 accuracy. The 22 barrel is mounted in between the rails, and held in place with the slide lock. If I introduce additional side play to the slide, I fear that will transfer over to the barrel. Currently as a 22, it is accurate and reliable. I am afraid to change that for the worse. I will however consider your thoughts.

Thank you and kind regards

Rich
 
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