Barrel Hood Fitting Jig

I hope my boss never sees my future projects list....

I'm putting it on it.

Greetings,

Would you kindly add a photo illustrating how the "rollers" mount to the jig body.

Cheers,

Dave

fc60,

I don't have such a picture at the moment.  But each roller runs on a spindle made of .250 drill rod which is permanently soldered into the jig body.  The spindle is drilled and tapped for a screw in its end.  Spindle length is controlled to stand a few thousandths taller than the roller to allow some up/down play in the roller.  The roller is turned to size, drilled and reamed to a .250 bore so there is no radial slop on the spindle, cut to length, and hardened.  It is held on the spindle by a screw and washer.  When mounted the roller has a little up/down play on the spindle but no discernible radial play.

I'll see about adding a picture.

I use the formula that Weigand has on his web site using this work sheet.  http://www.jackweigand.com/1911%20Barrel%20Hood%20Fitting%20Worksheet.html
Then I put the barrel in my mill and make the cuts.

Ok now the wrench in the gears!
The slide lugs are machined off center in the slide ;p)
Very common on older Colts. Now the centerline of the hood isn't aligned with the slide lugs. 
Jon

I have seen fixtures similar to Dr. Don's over the years, but it would be impossible for me to remember who or when they originated.
I too, like KC, use the Weigand formula of knowns and unknowns to compute the cuts. I also spend time truing and squaring up the hood  recess portion of the slide with guage blocks..   This is my rig.. It is an Accupro Truing Block. This allows me to do all the hood cutting and fitting in minutes instead of  hours..

The lower lugs are tapped into zero on the surface plate.

Both sides of the hood can be cut very accurately without removing or testing the fit..One of the joys of a surface grinder.

The barrel is set up on a guage block and the end of the hood is cut. The guage blocks allow barrel removal and return to zero to get that exact Jo Block fit.. The hood length does not require the barrel lugs to be on zero axis..

This is great stuff!

Jon makes a good point. The sides are not equidistant from bore centerline. The fixture would work if you switched bushings for each side.

Think the roller pins are offset from the bore centerline

I too use the Weigand formula as I have a mill. He has a great u tube video on the process

Jon,

Yes the hood is not centered on the bore axis.  But the roller spindles are offset from the bore axis by the same amount.  So you can indeed cut both sides of the hood by just flipping the file over to the other side.  Of course you have to have the correct OD rollers in place.

As for the slide lugs being off-center, I don't know how you would correct for that without altering the hood cutout in the slide. Am I missing something?

No you didn't miss anything, I just couldn't resist stating that if the slide lugs are off center because they were miscut that you're perfectly centered hood isn't going to be perfectly centered for those lugs. So when you start fitting the upper lugs it will push the barrel off center. On a typical new Caspian slide you won't have this problem, but on an old Colt slides in the last year I have fit three barrels and the slide lugs were crooked. I knew this up front so I had to compensate with the barrel hood and the upper lugs to reach a happy medium. if you go purely by the Weigand method it doesn't accommodate for that. So that's where old fashioned gunsmithing comes into play, because even though the upper lugs are oversized for example on a Kart barrel there isn't always enough meat to remove from one side to accommodate for the off center slide lug. I've worked on slides that pushed barrel off center enough that the slide wouldn't go on frame because the barrel lugs couldn't pass into the frame slot. Unfortunately many shooters cannot afford a new Caspian built pistol, so their old Colt becomes their match pistol. That's reality. And for the record Jerry Keefer is my hero! I can only dream of having his knowledge and his machine shop.
Jon

Jon,

Thanks for elaborating on this.  I had thought about it after your comment.  My tentative conclusion was that the Weigand formula was not going to address that problem either, and that old fashioned hand fitting with spotting blue and files might be the only way to get there.

And yeah, Jerry's setup and knowledge are really something!