Using a large diamond plate for flattening stock

G

Gerolld

Joined
Jun 30, 2015
Messages
6
This may have been asked before, but I can't seem to find it if it has.

I can't afford a surface grinder at this time, and using up seemingly endless sheets of sandpaper feels almost as expensive sometimes. Has anyone ever used one of those larger 8" or 10" diamond plates by DMT or Atoma to flatten stock, especially after heat treat? I'm sure it would still be labor intensive, but after just a few knives it should pay for itself (in sandpaper costs) if it worked. Sandpaper would still be needed in this case to get the desired final finish, but the diamond stone could soak up the material hogging job.
 
It would be a poor method, as the plate would quickly clog.

Just tape some low grit 3M or Rhynowet paper to a granite block of glass plate and do it by hand.

Tip:
Go in a figure-8 motion. If you go back and forth it will not end up flat.
 
I've tried using my DMT Coarse and XX-Coarse to flatten surfaces on blades and quite frankly they suck for that job. They don't seem to cut much faster than sandpaper and they leave huge grooves that are a monster to sand out (essentially defeating the purpose). They are great for lapping waterstones. You can buy a 100 sheets of 120 grit Rhynowet for about the same price as a DMT XX-Coarse, and I doubt the plate would last longer. I use a crappy 12-inch disk sander with an 80 grit PSA to flatten. I hold the piece with two welding magnets and I try to put very even pressure on all four corners. I then finish on a surface plate with 120 grit, using figure-8 motions like Stacy said.
 
As a general rule, diamond sucks for working with steel. In powered applications, the steel absorbs the diamond. In unpowered applications, diamond stones tend to clog up rapidly and because of its toughness and abrasion resistance, steel will tear up a diamond stone much faster than far harder materials do. Low grit PSA on a granite block is the way to go.
 
Thanks for the input. Using a disk sander sounds like a very good alternative to do the grunt work.

I don't mind finishing with the sandpaper off the grinder, but in my short sightedness I ground a couple chisel grind blades pre-heat treat. After quench they had a wonderfully successful warp due to the thickness variation of the grind lol. At the rate I was going I was gonna use up about $25 worth of 120 grit. Hopefully I won't forget that and make the same mistake again.
 
Gerolld said:
This may have been asked before, but I can't seem to find it if it has.

I can't afford a surface grinder at this time, and using up seemingly endless sheets of sandpaper feels almost as expensive sometimes. Has anyone ever used one of those larger 8" or 10" diamond plates by DMT or Atoma to flatten stock, especially after heat treat? I'm sure it would still be labor intensive, but after just a few knives it should pay for itself (in sandpaper costs) if it worked. Sandpaper would still be needed in this case to get the desired final finish, but the diamond stone could soak up the material hogging job.
Click to expand...
You can try scythe .It works for me when I use file jig to make some knives............

dB3Rzew.jpg
 
For flat sanding I use elmer's spray adhesive on the back of the paper to hold it to the granite. It lets me use the whole piece and keeps the edges from curling and is still only semi-permanent. For hogging tape might still be better just because of a reduced changeout time.
 
You can wear out a diamond Stone. Sandpaper is probably cheaper overall and it probably does the job faster too.

Also, I would not recommend using Diamond to flatten a stone. I've done it, it wears out your diamonds pretty quickly. This is a good application for a 220 grit or 120 grit silicon carbide paper.

I use 220 Grit silicon carbide paper on my Stones about once a week to keep them flat and sharp.
 
For flattening waterstones, use a master flattening stone. They are grooved to allow the swarf not to be trapped. Use lots of water.
I use a Norton flattening stone. They only cost about $30, and last a long time.

Using a 100 grit diamond stone to flatten a water stone is just inviting a stray piece of 100 grit diamond getting imbedded in a 8000 grit shiagi-to waterstone.
 
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