Checkering file question.

[jdm61]

I have a couple of Grobert checkering files (can't remember the new name of the company) and they are great tools. The only problem is that they only come in the flat models, so while you can do flat surfaces and convex surfaces like the front strap of a 1911 frame, you appear to be out of luck if you want to do something like put fine jimping on a convex or "inside" curve like a finger groove. To my eye, the jumping that you get form a course checkering file looks so much cleaner that jumping done freehand or with a dremel.

The problem is that I have yet to find anything like a "half round" checkering file anywhere, so I got to thinking. Could I make one myself? I was thinking that I might be able to forge out some W2 and grind it into the the shape of some different size half round files and then cut the "checkering" with the flat checkering file like you would do a front strap, then heat treat it to high hardness. Do you think that this would this work or would the cutting "teeth" not be sharp enough?

 

[logem]

It sounds like you may be stepping into detailed carving or graving to get the hollows checkered. Push/graving tools may be in your future? I think there are some very specific custom tools available for checkering hollows, but they may cost quite a bit. Check Midway USA or Brownells.

Sorry that I can't help much here.

Mike L.

 

[Joe Edson]

I cut a 2-line checkering file from my 20 line checkering file for this purpose. I did it with a dremel cut off wheel - lots of ice and a straight edge to make sure I only got a 2-line out. Took about an hour to cut, lol.

But for thumbnotches it works slow but great. Even checkering spaces at a 20-line per inch spacing without trying to do by hand.

Next time I'm just going to take a new file to the local waterjet cutting company and have them cut a bunch of 2 and 3-line files from it.

 

[jdm61]

I cut a 2-line checkering file from my 20 line checkering file for this purpose. I did it with a dremel cut off wheel - lots of ice and a straight edge to make sure I only got a 2-line out. Took about an hour to cut, lol.

But for thumbnotches it works slow but great. Even checkering spaces at a 20-line per inch spacing without trying to do by hand.

Next time I'm just going to take a new file to the local waterjet cutting company and have them cut a bunch of 2 and 3-line files from it.

That was Option #2, but it still says that the 2-3 line file is still flat so are the angles right when you use it on a curved surface?

 

[tim37a]

I did the same thing Joe did except I had it EDM cut into several 2 line and 3 line files. They work great although trying to jimp annealed M390 was pretty hard on them. Takes some practice to get nice cuts. What finally worked best was to use the files to makes marks and use knife files to make the actual cuts. The 2 line file works on 1/2" dia. circles.

Tim

 

[jdm61]

Tim, as best a I can tell you have no more than 10 rows of teeth on a 20 lpi file. How much "fudge room" did you leave for the heat affected zone from the EDM machine? My understanding is that it is not very big, but that you mostly have to worry about it on the initial cut and not so much on the later "skim" cuts. Also, how much did the job cost?

 

[12345678910]

How about you start with the file you want, then bend it length wise and re HT (protecting for decarb)

 

[KCGGBC]

Screw head slot files work really well in radii.

 

[jdm61]

Because the file cuts lengthwise and I want to cut across the radius.

How about you start with the file you want, then bend it length wise and re HT (protecting for decarb)

 

[tim37a]

The file was under water so as far as I could tell, there was no heat affected zone. He is a back yard machine shop so he charged me $50 or $100 to cut 2 files up. I can't remember now - the memory is the first thing to go!!

Tim