What grit ceramic belt to start?

M

milkbaby

Joined
Aug 1, 2016
Messages
644
I have a Grizzly 1x30 and have been using 50 grit zirconia as the first belt to hog off steel. But I basically need to use two fresh belts per knife because my grinder runs only one speed, i.e. super fast.

I was thinking of picking up some ceramic belts, they don't seem a lot more expensive. Should I drop down to 40 or 36 grit instead of starting with 50? I've been leaving a 400 grit belt finish so it hasn't been too big a deal leaving a few 50 grit scratches. Will 36 be any worse? I'm hoping lower grit will help with managing temps during post-HT grinding.
 
Basically, the 1x30 belt is running too fast, as you already know. I would drop to a 36 grit, but you will need to do frequent water dips if the blade is heat treated & you have to grind. The 400 grit will burn at the speed you have, so be careful. If you work up through the grits slowly (36, 50, 60, 80, 120, etc.), use fresh belts & just kiss the edge gently between water dips, that's as good as it gets. A 2x72 belt has 4 times more surface area, so it would run cooler & last much longer than anything you will do with the 1x30. Go slowly & don't apply much pressure, easy passes & you can do it.
 
Thanks noseoil! I've been dipping every single pass and also keep a spray bottle for the platen. Every single knife I've made is shorter or slightly different profile at the tip because it's so easy to burn out the HT when grinding afterwards.

I've been using Aldo's 1084 in 1/8" thickness with almost no warping out of the HT, but I'm worried about the other steel I recently bought since he's out of 1084 in that thickness. Now I'm worried about both warping and grinding post-HT, and want to do what I can to maximize success with the limited tools I have.
 
I try to run at the minimum thickness prior to HT & have as good a finish as possible. The better, cleaner & thinner the grind is before it's run through HT, the less work, easier grinding & nicer the finished product will be, at least from what I've found. Working with the tools you have will teach the best way to utilize them & learning will be much quicker if you get a chance to move up to a 2x72 at some point. Just keep plugging away at it.

If you go to a stainless (AEB-L is nice friendly stuff) you can run your grinds down to practically a finished edge & have very little clean-up to do. I've just gotten my first batch back & it's very nice to have so little to deal with in post HT work. I ran one down too thin & still had no trouble with it warping, but it's a small blade.

Actually doing my first 1084 stuff now. What edge thickness did you use for them before the quench & how were they to work with?
Also, how hard did you run them? I still send all my stuff out, since quality HT is fairly reasonable in batches.
 
I was trying to keep the 1084 edges to about 0.015-0.020" but know that I've accidentally gone even thinner and didn't have any major problems, never bacon edge. That stuff Aldo has is awesome.

I only have a two brick forge, so i go non-magnetic and then just a shade over, canola oil at 130F quench. No tester, but guesstimating I've tempered between 59-60 up to 63-64, included edge angle probably between 20 to 30 degrees. The hardest ones haven't been chippy, but only been used by me on wood cutting boards in the kitchen.
 
I don't know what speed that grizzly runs at but if I had to guess I would say 4500sfpm. If that's the case then there is nothing wrong with that speed. Yes it's fast but not faster then 99% of the 2x72 grinders out there. I hog metal at the speed all the time and 50grit is nice. Larger grit can strip off quicker if your not careful. At that speed I would not see any problem grinding up to 320+ grit. I would then hand sand from there on out. Drop back to 220gr paper and start hand sanding. But ceremic is the only way to go when dealing with faster speeds. I use to grind with ceremic blaze belts at just under 10,000SFPM.
 
Thanks JT and Benjamin! I'm so new to this, every bit of knowledge is helpful.

I calculated the sfpm of my 1x30 and it's just under 3300. I think the main problem is the small belts and tiny thin platen heat up very quickly and can't disperse heat well. Also, I'm using 1/8" and 3/32" steel which easy to heat up. The zirconia belts I've been using must break down quickly, so they're doing a lot more "rubbing" than "grinding" producing more heat from friction. That's why I'm wanting to try ceramics.

It's annoying because I feel like I'm just starting to get my grinds close to what I envision in my mind, but I'm always battling overheating and burning up the temper post-HT.
 
I went to a local tile supply house & had a small piece of gloss-finish tile cut for my factory (steel) platen. Glued it in place with JB Weld & it helps a bit with the heating problem and a small belt.

The small belts do tend to heat too quickly, especially at the tip of the blade, that's why a sharp belt & very gentle pressure with easy passes is as good as you can expect with the small belt size.
 
I only use a fresh ceramic belt to grind the last bit of material before hand finishing. For tips in general, look into an atoma diamond plate. They cut extremely well , I am starting to use this to get the really really thin tips finished as a step in between grinding and hand finishing. The atoma will last a long time as well as keep your other stones flat, also a much safer alternative to setting your secondary bevels than using a grinder.
 
You must log in or register to reply here.
Back
Top