1911 Barrel fitting

[Superkaratemonkeyfighter]

Does the 1deg barrel look up only come into play when milling clearance for the slide stop and fitting a comp ? 
The hood and sides are cut square ?

[shred]

The breechface is at 1 degree so yes.

[zzt]

Also dot mounts.  If your dot mount is parallel to the bottom of the slide, you may not have enough elevation adjustment to get it sighted in.  That requires a 1 degree shim from Ebay, etc.  If you are frame mounting and the mounting holes are parallel to the rails, you need a mount that already accounts for the 1 degree tilt.

[Superkaratemonkeyfighter]

Cheely frame mount and frame was drilled during his machining so I hope that figured in. 

trying to come up with a way to machine it in a mill without a fixture and a 5mm endmill. 

I can interpolate any size it’s just knowing who far to move forward before that 60*radius starts 
There has to be some dimension off the link pin hole I can use for a reference. 
just thinking out loud. 

[zzt]

1 hour ago, Superkaratemonkeyfighter said:

Cheely frame mount and frame was drilled during his machining so I hope that figured in. 

 

Holes are parallel to the rails.  His dot mounts figure in the 1 degree angle.  Fits perfectly.

 

Check your PMs.

[shred]

Yeah, some mounts put the angle in the mount, and some expect it in the frame holes, so verify before drilling...

[Cam73]

8 hours ago, Superkaratemonkeyfighter said:

Cheely frame mount and frame was drilled during his machining so I hope that figured in. 

trying to come up with a way to machine it in a mill without a fixture and a 5mm endmill. 

I can interpolate any size it’s just knowing who far to move forward before that 60*radius starts 
There has to be some dimension off the link pin hole I can use for a reference. 
just thinking out loud. 

 

-Indicate the center of the barrel link pin hole for X zero. I use a touch off, cut and check method for the Y axis.

 

-Cut towards the feet (X axis) .140" less the radius of your cutter. A 5mm cutter is the way to go. I've had to go past .140" to expose the disco slot in the slide a little more.

 

-The amount to be removed in the Y axis is the difference between the gage pin that the barrel will lock up on with uncut lower lugs and the diameter of the pin on the slide stop you intend to use. Confirm the barrel is pressed all the way up into the upper lugs while on the test gage pin by measuring and comparing numbers using the same method/location used while determining upper lug engagement earlier in the barrel fit. Triple check there is no barrel spring while checking upper lug engagement before determining the lower lug cuts! 

 

Even a simple fixture will save you a lot of time in set up and make the 1* repeatable as you test cut towards final dimensions using different gage pins. Depending on the brand of barrel, you might not have to worry about the radius forward of the link pin hole, but be sure to check for barrel bump once you have selected a link.

 

 

Edited April 25, 2023 by Cam73
Clarification

[shred]

17 hours ago, Superkaratemonkeyfighter said:

trying to come up with a way to machine it in a mill without a fixture and a 5mm endmill. 

I can interpolate any size it’s just knowing who far to move forward before that 60*radius starts 
There has to be some dimension off the link pin hole I can use for a reference. 
just thinking out loud. 

By 'interpolate' are you plotting to CNC the profile?

 

[Superkaratemonkeyfighter]

Thanks for the info.
Using a smaller endmill to Circular interpolate out to 5mm or .200. 
Or any size really. 

but yes putting it in a small program would be trick if it’s possible.

 

[MikeBurgess]

I have a small cnc and have milled the feet with the barrel square to the x axis and programed in the 1 degree, lots of math in the program but it worked fine, I ended up making a jig to hold the barrel at 1 degree so I could more easily write a program that was adjustable at the machine to allow me to walk my way in to the fit I wanted also it allows me to throw it on the manual mill if needed.

[Superkaratemonkeyfighter]

Think I got the fixture almost done. 
located the point at the end of the 60*

so I can just run the program to that point.  

that flat back up to barrel is to much figuring for me. I may just mill the bottom of the fixture at a 61* and put that on by hand. 
 

[MikeBurgess]

8 hours ago, Superkaratemonkeyfighter said:

Think I got the fixture almost done. 
located the point at the end of the 60*

so I can just run the program to that point.  

that flat back up to barrel is to much figuring for me. I may just mill the bottom of the fixture at a 61* and put that on by hand. 
 

I just ran my program straight from the end of the 60deg to inline with the link pin (Y0 in my case) most of the barrels I have fit lately are truncated there anyway so very little of that line is cut.

 

 

[Superkaratemonkeyfighter]

KKM one of those. 
I didn’t see how the link could come much past that 60deg but I thought I be safe. 
good to know 

[Superkaratemonkeyfighter]

On 4/25/2023 at 12:53 AM, Cam73 said:

 

-Indicate the center of the barrel link pin hole for X zero. I use a touch off, cut and check method for the Y axis.

 

-Cut towards the feet (X axis) .140" less the radius of your cutter. A 5mm cutter is the way to go. I've had to go past .140" to expose the disco slot in the slide a little more.

 

-The amount to be removed in the Y axis is the difference between the gage pin that the barrel will lock up on with uncut lower lugs and the diameter of the pin on the slide stop you intend to use. Confirm the barrel is pressed all the way up into the upper lugs while on the test gage pin by measuring and comparing numbers using the same method/location used while determining upper lug engagement earlier in the barrel fit. Triple check there is no barrel spring while checking upper lug engagement before determining the lower lug cuts! 

 

Even a simple fixture will save you a lot of time in set up and make the 1* repeatable as you test cut towards final dimensions using different gage pins. Depending on the brand of barrel, you might not have to worry about the radius forward of the link pin hole, but be sure to check for barrel bump once you have selected a link.

 

 

That’s for the info it all worked out. 
Hiw much of the disco slot in slide did you shoot for ?

mine is in the hole but not centered by any means 

[Cam73]

On 5/5/2023 at 5:49 PM, Superkaratemonkeyfighter said:

That’s for the info it all worked out. 
Hiw much of the disco slot in slide did you shoot for ?

mine is in the hole but not centered by any means 

That's great.

 

Someone more experienced can chime in on this, but I think as long as the disco can move through it's entire range of motion and be restrained by the sear pin at the top of it's travel and not stopped by the timing recess before that point, you are good to go.

 

I look for the timing recess in the slide to be visible through the disco hole in the frame while in battery and not the flat disco rail, The disco head will be at the very start of the timing recess. This is normally coincident with the slide being forward enough to engage the thumb safety, but not a guarantee.