Cutting groove for O rings

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DaveRC

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I need to cut grooves for some O rings, all on the lathe, these are quite small, 1mm width and into Stainless Steel (303) and need to be a really good fit. (Going to be holding 150BAR of pressure)

What tool would be best, grind down a HSS parting tool is about the only think I can think off so far.

Thanks

Dave
 
Dave,
303 is one of the nicer cutting S.S. so making and using H.S.S. is fine but I wouldn't make it from a parting tool. There's too much to grind from the sides to get it to thickness. Just use a square H.S.S. lathe bit. I would use a .250 blank. Much less to grind. I always start from the left side of the blank and grind my clearance on then slowly work in from the right side to get the desired thickness. Keep a water container handy to cool the blank when it starts to get hot. And keep your wheel dressed.
gbritnell
 
Thanks for that, I now have some blanks on order along with a dressing tool (about time I got one anyway).

Dave
 
Hi Dave,
For very small grooves, to make a very clean job of it, I have found I need two groove cutting bits, a RH and a LH. Each one cuts one sidewall, a bottom corner, and half the groove width. I think I made one set of these from broken SS drill bits grounds away until there was only a wee nubbin of a cutting tooth. But everyone discovers his own way though.

As for fits, it might be very beneficial to have one of the several O-ring "bibles" in your resource library. O-ring fits and clearances aren't always logical or intuitive, they need what they need. The "Parker" O-ring book is well respected one that come to mind first, I've had mine for years, although there are probably others just as good, and probably now all updated and on-line.

PS - Here it is http://www.google.com/url?sa=t&rct=...sg=AFQjCNHXAzA-cmKyp-vKwU9UlZ0z3mkcNg&cad=rja
 
Last edited:
If you visit www.uxcell.com. you will find packets of HSS blanks of the size you are after for only a few dollars. Simply put an angle on the face, make a block to hold them in for your tool holder & you can easily make a perfect groove of the exact size. I use them slightly under center height. I think they are sold as graving tool bits, or try HSS on their search. Takes a bit to find what you are after but worth it, & good service with free postage after your first buy.
All disclaimers - just a happy customer.
 
Thanks chaps, some interesting reading and some good ideas, will give me something to work with.

Dave
 

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