Recommendation? Bevel vs Flat disc grinder

[weo]

I think people are overthinking the arc thing. On a 2" wide blade with a 1° arc angle, the hollow is .005". And that is assuming you hold the knife at an exact center to edge orientation. If holding the knife at 45° to the edge-center line the hollow is less than 1/1000 of an inch.

True, but like I said above, when hand sanding using a flat piece of G10 as a sanding stick in preparation for etching, the hollow is very apparent and for me, takes longer to sand out than what comes off my 2x72. I haven't tried using my sanding stick with the leather piece glued on. That may give enough 'give' to make the hollow a non-issue.
I may just have to spend more time on the disc grinder, though.

 

[N.W. Gean]

Update: I got the disc today, and played with it some. I'll post some pics tomorrow. Having an issue with facets but am quickly learning that approach is very important. I have yet to notice the 1 degree bevel hurting anything. Does stop the other side from grabbing though.

I have read about people using thin cork or hard rubber backings on the disc to smooth the chatter, but would this defeat the purpose of making things flat?

Edit: Also, from watching youtube videos, I get the feeling that I'm grinding on the wrong side of the disc but I'm not sure. If when facing the disc it's turning left, should I be using the left or right side? if I try the left it's extremely grabby but that seems to be how it's done in the videos.

 

[Crag the Brewer]

Update: I got the disc today, and played with it some. I'll post some pics tomorrow. Having an issue with facets but am quickly learning that approach is very important. I have yet to notice the 1 degree bevel hurting anything. Does stop the other side from grabbing though.

I have read about people using thin cork or hard rubber backings on the disc to smooth the chatter, but would this defeat the purpose of making things flat?

Edit: Also, from watching youtube videos, I get the feeling that I'm grinding on the wrong side of the disc but I'm not sure. If when facing the disc it's turning left, should I be using the left or right side? if I try the left it's extremely grabby but that seems to be how it's done in the videos.

Any more Current updates?

I'm leaning towards a beveled disk, as I like large blades.....
are you getting the hang of it, and using it often?

I'd love to hear more peoples view on this.

I too am curious as to how to address the disk/rotation/blade positions too?

videos with grinding (also with 2X72) don't always show blade edge direction, and belt direction.

 

[weo]

Edit: Also, from watching youtube videos, I get the feeling that I'm grinding on the wrong side of the disc but I'm not sure....

I too am curious as to how to address the disk/rotation/blade positions too?

I think the answer depends both on what you are trying to accomplish, what your motor can do and what works for you. In general, you want the rotation of the disc to be going away from your face so that if you lose your grip, the piece is thrown away from you, (down) and not up at your face.

Hopefully you have a reversible motor so that you can change the direction of the spinning disc so you can be doing the same thing on each side of the blade. A lot of folks will grind edge up for rough grinding, then edge down for putting on the final edge.

 

[Crag the Brewer]

I think the answer depends both on what you are trying to accomplish, what your motor can do and what works for you. In general, you want the rotation of the disc to be going away from your face so that if you lose your grip, the piece is thrown away from you, (down) and not up at your face.

Hopefully you have a reversible motor so that you can change the direction of the spinning disc so you can be doing the same thing on each side of the blade. A lot of folks will grind edge up for rough grinding, then edge down for putting on the final edge.

Thank you. Did you ever get use to it being hollow grind? do you regret it?

I made a motor mount, so all I need is the disk. I think it will be easier to shape my blade tips on this compared to my belt grinder, idk?

 

[N.W. Gean]

Any more Current updates?

I'm leaning towards a beveled disk, as I like large blades.....
are you getting the hang of it, and using it often?

I'd love to hear more peoples view on this.

I too am curious as to how to address the disk/rotation/blade positions too?

videos with grinding (also with 2X72) don't always show blade edge direction, and belt direction.

Haven't used it in a while. Got tired of switching and motors are expensive. Ended up building an SGA and being happier with that, given that I really just wanted a reliable method of flattening scales and steel.

 

[jefflynnjstar]

I use both, but like the 1° bevel disc. It isn't "grabby" on a blade with a length over 5".
I think people are overthinking the arc thing. On a 2" wide blade with a 1° arc angle, the hollow is .005". And that is assuming you hold the knife at an exact center to edge orientation. If holding the knife at 45° to the edge-center line the hollow is less than 1/1000 of an inch.

i have a 9 inch beveled…. I do no actual blade , bevel grinding on it. I bought it to finish flats vs using a flat platen 2x72,,, Will it work for finishing the flats above the hollow grind at the spine…. ????? The flats only??? And how will it work on truing up wooden/ micarta scales…. ?????

 

[LCoop]

I may be wrong. I've been there before. But I think Stacy may have changed his opinion. I do know I like my flat disc grinder.

 

[Stacy E. Apelt - Bladesmith]

Yes, after more use I found little difference between the two. It was more of a technique issue.
Making the disc grinder VS was the biggest thing I would recommend to anyone.