How to sharpen keyway cutter

[D.sebens]

I have a hss keyway cutter that the relief has been ground flat. The thing won’t cut to save its life. What’s the best way to restore?

Edit: after searching around I guess this is a slitting saw?

 

[D.sebens]

I need to use it for one job of a few cuts. It is on a horizontal milling machine I am trying to sell. I am using that machine to fix my other mill. I could purchase a new cutter if need be but would rather not.

 

[benmychree]

It can be sharpened, but it would pretty much need a tool & cutter grinder to do it, and yes, it is a slitting saw (with side relief}.

 

[markba633csi]

Maybe you could try running it backwards against a wood block with some emery cloth fastened to it- a sort of hone. Might sharpen enough for
the one slot you need to cut
???

 

[D.sebens]

I might try that. I found two b&s new old stock cutters on eBay for $20 for the set. I ordered them and will keep them with the mill I’m keeping in case I need them some day.

 

[benmychree]

Maybe you could try running it backwards against a wood block with some emery cloth fastened to it- a sort of hone. Might sharpen enough for
the one slot you need to cut
???

That is just plain ridiculous! Cutters need to have angular relief on cutting surfaces that need to be able to cut, period, If a person had a tool post grinder and devised a tooth rest, it MAY be possible to sharpen it on a lathe, secondary relief coule easily be done by hand on a bench grinder.

 

[D.sebens]

I think that would work if I still had back relief. I don’t think it would work for me though.

 

[benmychree]

I might try that. I found two b&s new old stock cutters on eBay for $20 for the set. I ordered them and will keep them with the mill I’m keeping in case I need them some day.

That is the best thing that you could have done, perhaps someday you also might be able to sharpen the other one that you have, bear in mind that cutters need a positive relief angle on the OD to be able to cut likely in the order of 3-5 degrees.

 

[chapmansean]

If the rip saw cavities are ground flat, they must be reground to the correct clearance angle for a proper cut.

To restore the relief, you can use a bench grinder or a tool with a diamond disc and a cut-off his grinder. After setting the angle of the relief correctly, the relief must be carefully put back into the saw. Take your time and fine-tune the angle until you get the result you want.

If you are unsure if you can sharpen the relief yourself, you should take your saw to a professional tool sharpening service. They have the equipment and expertise to regrind reliefs and restore saw cutting performance.

 

[benmychree]

I think that one could easily replace most dull cutting tools by shopping on e bay, for less cost than a professional sharpening job, as has already been shown by the original poster's deal made for two new cutters for $20.