Q:

Need advice – cutting inside o-ring

I want to make a new breech. What is the best way to cut the inside o-ring groove. Any pictures of homemade cutting tools would be great.

Thanks

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Thanks for all the idea’s so far. I have a few more days at work and then I can get home and try them.

Another good way Saw hss square bits work well and in your case you will be using a small boring bar? a good way to shape a hss square tool bit is to mount it in your boring bar tighten up the set screw that holds it in and grind it to the size and shape you want it to be, keep a pan of water by your grinder to keep the tool from getting to hot or it will loose it’s hardness I have a couple jigs made up just to hold hss square lathe bits, you get a better feel for grinding and keeps your fingers save and also cooler!

i ground an allenwrench…it will work ok….is easy to sharpen…and they seem to come with everything …i dont use my good allenwrenches….just the cheap ones that ikea and such thows in their kits…..i had one that just kept going and going…..

i took an good sized allenwrench or punch i cant remember bored a hole in it…hammed a broken drillbit in there and gound it sharp…that will cut nice grooves and even internal threads…the drillbit i hammered in there is hard as nails and i havent had to resharpen it yet

I used a grinder and beltsander to grind a j shape in an hss lathe bit blank and made the point like .0002 smaller so the oring had a sug fit. No idea how to post pic lol

Thanks jezx,

I thought I seen a post a while back where they cut and used a 3/8 drill bit rod in a boring bar holder. I think I will try and use the chop saw and bench grinder to make one, as you described.

take a chop saw an slowly cut in from the side on a tool bit ( dont over heat), leaving about .05” sliver for the cutting edge, cut in deep enough to get in side deep enough .. . with clearance on both for cuttin edges .
cut the bottom off the tool til it fits it the hole easy top to bottom, rised above center ..( cutting face with lots of clearance . )

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