Recreating Cutts compensator

[choppero]

I am doing a recreation of the Cutts compensator. I have a print calling out a 46 deg dovetail. This translates to a 67 deg dovetail cutter.???? I can't verify the originality of the print but the sights off an original and a Kahr do appear to match that. Right now there are 80 of these on the bench waiting for that dovetail. Anyone know who could tell me? Doug Richardson has passed and I don't know who got the prints.

[reconbob]

   There is no reason for the 46 degrees. Use a 45 degree and you will be OK.

Bob

[choppero]

Thanks Bob I have taken a picture of My CAD representation along side the print. And another picture of the sight sitting in a 45 deg dovetail cut.

Tom

[laurencen]

the angle cut in the Cutts looks double what it should be

[Chip]

From your drawing, I would agree that the toe of the cut is 67 degrees from horizontal and 23 degree from vertical.  I don't know what the original angles were, but the sight you have looks to be the same as the cutts and sight I have.

Edited April 16, 2023 by Chip

[choppero]

is there anyone with the cutts print? If this print of mine is accurate, it's a start toward having some cutters ground.

Edited April 16, 2023 by choppero

[anjong-ni]

http://www.nfatoys.com/tsmg/pdf/5564369.pdf

 

Here is the print of the compensator. ...Phil

[choppero]

Thanks Phil. It seems the print I have is accurate. I wonder if the dovetail cutter exists somewhere?  My tig instructor gave me a company in CA , H&L Precision grinding. I'll. give them a shout for a quote. Any other leads would be appreciated.

Thanks again,

[reconbob]

    Chip has got it right here. I made a mistake - 46 degrees is not the angle of the

cutter, it is the included angle of both side of the dovetail. So I think you are going

to need a custom grind for this. See photos - the dovetail in an original comp is clearly

not as sharp as your sample. And I put an angle gage on one side of the dovetail and

it sure is close to 67 degrees.

 

Bob

[laurencen]

48 degree dovetail cutters are available, I would try one before I have one custom made, it would be easy to alter it to 46 degrees on a cutter grinder or a surface grinder with a 5C index fixture 

[choppero]

I've found 36 degree cutters and will try one. The included angle throws me. I have yet to find a company description using included angle. If Laurencen knows of a source I would like to see. Since this intended to be a drive fit, it may be acceptable using 36 degrees. Now finding available sights at a reasonable price may be a challenge also. 

[laurencen]

hi choppero, take a look at Harvey tool, here is a link ,https://www.harveytool.com/products/dovetail-cutters---parker-hannifin-o-ring-dovetail-cutters-with-drop-hole-allowance they show 48 degree included angle cutters

what machine are you cutting the dovetail on, if a 4 axis CNC chuck the comp in the rotary axis use a standard cutter and rotate it to get the right angle, 

[choppero]

Good source laurencen. In stock 2 flute coated or uncoated. I am cutting on a 4 axis using collet. With the correct angle cutter I need only make my 1/4" relief cut and cut straight in. Frankly I had not considered rotary comp. For 1 off that is handy to remember. Thanks.

[anjong-ni]

 

I notice that the pistol slide dovetail angles are measured "down to the slide" like this ATI.

So the Thompson compensator would be "67-degrees", right?

Surely there is a pistol dovetail cutter that matches this closely enough ("Drive fit").    ... Phil

 

[choppero]

It seems you have experience with CNC laurencen. I have not used a 2 flute dovetail cutter before. Harvy tools has a good tech department and speed and feed charts. 2 flutes, it would seem, have greater flute strength. I'd really hate snapping a $104 cutter out of ignorance. any advice? I appreciate your input here.

Edited April 18, 2023 by choppero

[laurencen]

2 flute is no different to 2 flute end mills, if it were me I would make a pass with a slot drill then use the cutter to remove the angled face, way less load on the cutter.

$104 is not that bad just use lots of fluid to get chips away dovetail cutters do tend to plug up easier than standard milling cutters

[Got Uzi]

The other thing with a dovetail cutter to keep in mind is it’s better to rough the slot in with a standard endmill and then cut the corners out with the dovetail. The key is to not go too wide on the roughing. You only want to clear out the center. Leave .005-.010 on the bottom for it to clean up. I’ve cut several pistol slides and custom red dot mounting plates this way and it works well. 
 

Feeds and speeds, that all depends on the material, tooling holder, material holding and machine. A chart will o Lt get you so far, but what the “chart” says will work, doesn’t always translate to real life…been there, learned that. 

[choppero]

All great advice. I had planned on using a 1/4 endmill as is called out in the print. I too have cut many dovetails in barrels and slides always with a slot. But not often into a pocket. The tech at Harvey indicated that it may take 2 to 3 passes each side. 

Edited April 18, 2023 by choppero

[laurencen]

trick with a pocket do not cut fill depth more as you widen the cutter increase the depth, I run them at a lower RPM and feed rate to avoid chatter