Flat Grinding on Disc Sander

Mike Martinez

Mike Martinez

Well-Known Member
Those of you who use a disc grinder to true your flats, how do you keep your plunge line clean? I'm going to give it a try but am weary about screwing up the plunge lines.
 
I suppose that you get close to the plunge then gradually pull the blade up? perhaps you only take the disk to the plunge and stop?

Good luck anyhow
 
I've got cork on my disk which is rounded around the perimeter. The radius in my plunges is miniscule though so the edge of the disc will bump into the plunge instead of tearing it up.

If your plunge is more rounded you may get a different result than I do. No cork may also cause it to bite.

The only area with any real danger of a flub is the very top of the plunge where it meets the flat/spine. I just stay out of there with the disc.

With the disc I'm not really truing the flats per-say. My purpose is to use the disc to save hand finishing time which it does well for me. The disc will show you clearly if you have anything that needs fixing on the bevels.

If I find an issue after hitting the disc I'll fix it on the belt typically then go back to the disc.

A lot of the plunge issue is going to be determined by your plunge geometry and the thickness of the blade. It's fairly easy with thin stock to run right over the plunge and trash the ricasso so be cautious of that.

Go for it ! It's not as bad as you might think.

-Josh
 
Josh Dabney said:
I've got cork on my disk which is rounded around the perimeter. The radius in my plunges is miniscule though so the edge of the disc will bump into the plunge instead of tearing it up.

If your plunge is more rounded you may get a different result than I do. No cork may also cause it to bite.

The only area with any real danger of a flub is the very top of the plunge where it meets the flat/spine. I just stay out of there with the disc.

With the disc I'm not really truing the flats per-say. My purpose is to use the disc to save hand finishing time which it does well for me. The disc will show you clearly if you have anything that needs fixing on the bevels.

If I find an issue after hitting the disc I'll fix it on the belt typically then go back to the disc.

A lot of the plunge issue is going to be determined by your plunge geometry and the thickness of the blade. It's fairly easy with thin stock to run right over the plunge and trash the ricasso so be cautious of that.

Go for it ! It's not as bad as you might think.

-Josh
Click to expand...

Thank you Josh, its always nice to hear from someone of your calibre and knowledge.
 
Mike,you are right to be concerned about screwing up your plunges when switching to the disk grinder but I believe your going to have to screw some up in order to learn how to do it.
I hollow grind my blades first on a 14" wheel then switch to a 9" disk. I grind a lot off toward the tip and less at the plunge so that the plunge is mostly ground on the disk grinder.
I hope this helps a little. You might want to grind some blades out of cheap mild steel to get the hang if it before grinding real blades.
 
Calvin Robinson said:
Mike,you are right to be concerned about screwing up your plunges when switching to the disk grinder but I believe your going to have to screw some up in order to learn how to do it.
I hollow grind my blades first on a 14" wheel then switch to a 9" disk. I grind a lot off toward the tip and less at the plunge so that the plunge is mostly ground on the disk grinder.
I hope this helps a little. You might want to grind some blades out of cheap mild steel to get the hang if it before grinding real blades.
Click to expand...

Thank you Mr. Robinson, I was thinking that the "gods," of blades would take a few sacrifices before it came together for me. :)
 
Knifemaker.ca said:
Sorry Cal. My imagination must be lacking. :confused2: How do you clean up a hollow grind on a flat disc? Working over the edge of the disc at an angle that fits the hollow???
Click to expand...

I'm sorry for not explaining myself completely.
I start my FLAT grinds on a 14" wheel,to take off the bulk of material because its quicker than the disk. Then I switch to the disk to finish them up,flat.
 
Hey calvin, any chance you could take some pics or maybe a short video on what you do with the disc? I am fascinated and think a disk grinder from kmg is next but want to see how its done if possible.

Thank you
 
Timy said:
Hey calvin, any chance you could take some pics or maybe a short video on what you do with the disc? I am fascinated and think a disk grinder from kmg is next but want to see how its done if possible.

Thank you
Click to expand...

Timy,
Maybe,one day,when I get a helmet cam.:biggrin:
 
Hey Calvin - I can come over some day to help with video if you wish. You grinding 'n talking while I hold camera and learn<:)

Ken H>
 
KenH said:
Hey Calvin - I can come over some day to help with video if you wish. You grinding 'n talking while I hold camera and learn<:)

Ken H>
Click to expand...

Ok Ken,that will work but it will be after Thanksgiving day,I'm going to be REAL busy until then.
 
After Thanksgiving works good for me also - nice winter project<:) I've got a buddy that's decent editing videos and maybe I can get him involved also.
Ken H>
 
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