Type of File for Thinning Rim Diameter

[Rfeustel]

Hi,

I do not have a lathe and need to thin some rim diameters (30-30 -> 225 Win). I’m a metal working noob, but I have a proper, variable speed drill press. I’ve read people chuck the case in a press and use a file.

What kind of metal file would I use? I thought it would be a single cut, but then I read a double cut is better for brass. Then I read about “mill files” for use on a lathe. But that seems like over kill.

I’m trying not to go from rimmed, to rebated rim, in .00002 seconds. LOL.

Any thoughts from experienced people would be greatly appreciated.

Thank you.

[Mk42gunner]

I don't know which type of file would be best for brass. Seems like I used a 10" Mill Bastard file when I was converting brass, but that has been a few decades ago.

One word of warning: Handles. Using a file on something turning under power is the one place I insist on having a handle on a file. I have heard or read too many stories of the file getting thrown back at the operator to want to chance it. A file tang at speed could produce a horrible wound.

Oh and don't wear loose clothing or jewelry.

Robert

[Winger Ed.]

I don't know which type of file would be best for brass. Seems like I used a 10" Mill Bastard file when I was converting brass, but that has been a few decades ago.

One word of warning: Handles. Using a file on something turning under power is the one place I insist on having a handle on a file. I have heard or read too many stories of the file getting thrown back at the operator to want to chance it. A file tang at speed could produce a horrible wound.

Oh and don't wear loose clothing or jewelry.

Robert

^^^^ this ^^^^

The brass will 'give it up' and wear down easily.
So get a fine one with shallow grooves real close together.
And also a stiff brush to clean it out when it clogs up.

Rubbing chalk into the grooves will help some, but it'll still clog up.

[kootne]

A couple more hints, use a file with a "safe" edge, meaning no teeth on that side. Does a lot nicer job.
As far as cleaning out the teeth when they clog, take a fired cartridge case, (I use -06) flatten the mouth and shoulder in a vise. To clean the file, push the flat end over the teeth, parallel to the teeth. Hold the brass case tipped up up at about 30 degrees. It will quickly form the pattern of the teeth and you can push out the clogged metal and everything else that is in the grooves between those teeth. Works better than any wire brush or file card.

[NyFirefighter357]

^^^^ this ^^^^

The brass will 'give it up' and wear down easily.
So get a fine one with shallow grooves real close together.
And also a stiff brush to clean it out when it clogs up.

Rubbing chalk into the grooves will help some, but it'll still clog up.

Soapstone works as well.

[Rfeustel]

Wow, so much wisdom here. There was so much I was about to do wrong, including hurt myself. I love this forum.

[country gent]

a swiss pattern fine file with safe edges will give a very nice finish look at the grobert files. A file with both sides safe is best you dont have to check each time. Another couple tricks 1) clean the new file with solvent before use this removes protective oils and loading. 2) load the file with chalk this reduces loading and pinning also lubricates the cut. 3) use a tooth brush to clean small files.

[cwtebay]

I have used a Swiss pattern file with a single safe edge for all of my rim thinning and extractor groove business.
I do soapstone it before use and use a steel brush afterwards to clean.
I generally use a piece of emory cloth wrapped around a thin piece of oak to make 'em purdy.

Fwiw - a safe sided half round bastard file in the groove above the rim of your 30wcf cases is perfect for making 225 brass. I don't own a lathe, but I chuck the neck into my drill press arbor and use it as such. I've made hundreds of them that way, definitely doesn't take long!!

Sent from my Pixel 5 using Tapatalk

[Rfeustel]

a swiss pattern fine file with safe edges will give a very nice finish look at the grobert files. A file with both sides safe is best you dont have to check each time. Another couple tricks 1) clean the new file with solvent before use this removes protective oils and loading. 2) load the file with chalk this reduces loading and pinning also lubricates the cut. 3) use a tooth brush to clean small files.

Thank you Sir Gent. I’ll check out the Swiss pattern file.

[Rfeustel]

I have used a Swiss pattern file with a single safe edge for all of my rim thinning and extractor groove business.
I do soapstone it before use and use a steel brush afterwards to clean.
I generally use a piece of emory cloth wrapped around a thin piece of oak to make 'em purdy.

Fwiw - a safe sided half round bastard file in the groove above the rim of your 30wcf cases is perfect for making 225 brass. I don't own a lathe, but I chuck the neck into my drill press arbor and use it as such. I've made hundreds of them that way, definitely doesn't take long!!

Sent from my Pixel 5 using Tapatalk

Mr cwtebay, are you saying lay the safe edge against the web portion of the case, file side turned toward the rim, to thin the rim thickness? Or does it thin the diameter, or both?

[Rfeustel]

To those like me who didn’t know, Grobert are a brand. Very nice!

[cwtebay]

Moved

[cwtebay]

Mr cwtebay, are you saying lay the safe edge against the web portion of the case, file side turned toward the rim, to thin the rim thickness? Or does it thin the diameter, or both?I've never had any need to alter the diameter of the web, only thin the rim. I rest the cutting surface on the back side of the rim, the safe edge against the web.

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[Scrounge]

https://toolmonger.com/2010/01/11/a-good-read-file-filosophy/ Some links of use to people who want to learn about how to use a file.

https://archive.org/search.php?query=filosophy&and[]=mediatype%3A%22texts%22 also several versions of the File Filosophy book from Archive.org

Remember that the guys who built the Industrial Revolution started with hammers and chisels, hacksaws, and files.

Bill

[seetrout]

In case you want to save those .30-30's and some time and effort.

https://www.opticsplanet.com/winchester-ammo-reloading-225-win-wws-usc-rifle-brass-case.html

Says in stock, but who knows for sure.

[Rfeustel]

I've never had any need to alter the diameter of the web, only thin the rim. I rest the cutting surface on the back side of the rim, the safe edge against the web.

Sent from my Pixel 5 using Tapatalk

Understood. Thanks!

[country gent]

A simple "jig" for this an be made up from 1/4 X 2 flat stock about 6" long.

Drill a flat bottomed hole along one edge to the depth you want the rim thickens slightly larger in dia. this leaves a recess for the rim to sit in.
Bolt to drill press table with the hole aligned with spindle.
Lower rim into recess. lock spindle
lightly lay file on pads and slowly push forward. When the file stops cutting your to thickness.

[uscra112]

The commercial name for the file you want is "lathe file".

https://www.amazon.com/Nicholson-Hand-American-Pattern-Rectangular/dp/B001HWJT5W/ref=sr_1_5?dchild=1&keywords=lathe+file&qid=1628945018&sr=8-5

Lathe files are cut with a high skive angle so they cut smoother on a spinning workpiece, and have safe edges.

I've used files like the one I linked to for reducing both web diameter and rim thickness on hundreds of cases.

[Rfeustel]

https://toolmonger.com/2010/01/11/a-good-read-file-filosophy/ Some links of use to people who want to learn about how to use a file.

https://archive.org/search.php?query=filosophy&and[]=mediatype%3A%22texts%22 also several versions of the File Filosophy book from Archive.org

Remember that the guys who built the Industrial Revolution started with hammers and chisels, hacksaws, and files.

Bill

This is pretty cool. I got the 1954 edition downloaded.

[Rfeustel]

In case you want to save those .30-30's and some time and effort.

https://www.opticsplanet.com/winchester-ammo-reloading-225-win-wws-usc-rifle-brass-case.html

Says in stock, but who knows for sure.

Only 2 weeks-1 mo for shipping allegedly. We’ll see. Thanks. It’ll be good to see the real thing.

[Hahndorf1874]

I found a Stihl chainsaw raker file is great for this application,fine cut,also has safe edges as well.

Cheers Mal in au.

[Rfeustel]

A simple "jig" for this an be made up from 1/4 X 2 flat stock about 6" long.

Drill a flat bottomed hole along one edge to the depth you want the rim thickens slightly larger in dia. this leaves a recess for the rim to sit in.
Bolt to drill press table with the hole aligned with spindle.
Lower rim into recess. lock spindle
lightly lay file on pads and slowly push forward. When the file stops cutting your to thickness.

Thanks, country. Trying this. If it all works out I’ll put up an informative post.

[barrabruce]

Hacksaw blade
Run it flat along the case teeth onto the shoulder.