Surface and disc grinders?

Fletch Helical

Fletch Helical

Joined
Sep 29, 2009
Messages
1,614
From what I've been reading about these 2 machines seem to have a special place in the hearts of a lot of makers. My question is: What makes them so different than say putting a piece of metal flat against the platen on your grinder? Most people here are sing some kind of glass, tile, etc platen to grind against. Why not just get one of those welder magnets from say Harbor Freight, stick it to the blade and press it flat up against you platen to flatten metal out. Or use the same platen for flattening out scales? While I'm all for more toys s much as the next guy, what makes these 2 tools so much different than a grinder?
 
It's nearly impossible to get a true flat with a belt grinder on the platen. Yes, with practice you can get close, but even then it will not be truly flat. What happens on the grinder is that you tend to get a bow in the belt when you push it against the platen. Even when the platen is set up as close to perfect with the belt as possible, when you push the material into the belt/platen, the belt willt tend to take off more material on the tops and bottoms of the piece.

When precision matters, a surface grinder, hand lapping (done correctly), or a mill is about the only way to get truly flat. A flat disc can also get closer to true flat than a belt grinder, and it's generally close enough for the majority of blade work. For things like folders or very intricate assemblies, it would be hard to beat a surface grinder.

--nathan
 
Nathan for the most part hit it spot on, but he left out one thing with the surface grinder. Not only will the SG make the surface flat, but you get parallel also. I had a couple blades that I had hand sanded on the granite plate till I thought they were flat, working a little harder in the ricasso area. Anyhow, I took those blades and put em on the surface grinder just to see how good my work was, and it was not even close. Sure, I kinda expected that. However, when I flipped the piece over the grind went way different cause the high spots were different. Some of that has to do with the material I removed on the other side but for the most part you could tell although they looked the same on both sides they were finished to different thicknesses in different spots.


I love my SG. that was the best purchase I made this year. Granted, it was almost a G for it, but I have been nothing but happy with it as long as I do my part. I just got my coolant mister rigged this weekend, and it did not cost an arm and a leg. Need a bigger tank though.
 
All great points above, but one other thing a Surface grinder does that no-one has mentioned yet. Try to take off .0015 of your blade using your sander.
If you get into folder making, the blade and spacers need to be spot on.
A SG can easily do the task above as well as keep both sides of your parts parallel.
Chris
 
You must log in or register to reply here.
Back
Top