grinding belt problem

Joined
Apr 4, 2001
Messages
1,803
Help the FNG!
I'm new to this so I've only used one brand of grinding belts on my grizzly.
I've been using belts from Industrial Abrasives.
When I finally got around to (flat) grinding down to a finer grit (120 to 320) instead of hand sanding, I find that the butt joint causes 'deep marks/ripples' that show up after 120grit finish and simply move around as I try to grind them out as a result of striking the butt joint.
I suspect these belts would be OK for slack sanding or hogging out but for finishing up, I'll need something else. I'll take any all reccomendations.
Thanks.

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Greetings tmickley.
The reason for this is really quite simple although you may not want to hear it ( I know I didn't!) You are pressing too hard! and why are you pressing sooooo hard against that platen? Beause your <atronge><u>BELT IS WORN OUT!</stronge></u> Actually it took me forever to learn one of knifemakeing's simplest facts: don't use worn out belts. I bet both Bruces' (Bump and Evans) will agree; when a belt stops "cutting", toss it! YOu should, in any given grit, feel that almost "new belt cut" with whatever your useing or it ain't work'n. Remove your flat platen (by now, I bet it has a gouge or two in it's face yes?) re-sand it flat,( I use a 6X48 to ocassionally do mine), and put on a new belt and those gouges in your nice new blade will go away.
Now, you said in your post: "When I finally got around to (flat) grinding down to a finer grit...", I surmise you've been flat grinding all along? yes? if not, tell us what you are doing.
I too have used Industrial abbrasives products however you get what you pay for; they wear out quickly and of grater importance, don't track so great. The belts I use are the "Klingspore" brand LS312, and LS309 belts. Either one is ok by me. My regimen is this: first, no belt at all!! That scale on a freshly forged and normalized knife blade is about rockwell 60 or even better, why waist belts on this stuff? I use two different welder's angle grinders (one big one small) to get down to white steel, an immediate savings in belts, next, your choice; some use 36, some 50, others 80 grit for the initial shapeing of the blade, next it's 120, then to 220, then to 320 and that's it. After 320 you can leave it lay or hand sand or use a 3M scothbrite belt, whatever. What you <stronge>can't do</stronge> is try and clean up a mistake made in the rougher grit with a lesser one; even though it's just out of 36 grit, it has to be "right" in order to go on to 120. And lastly, use belts that still cut!!! I will say that those of us that have variable speed are spoiled. In the grits from 220 on down, you need less surface speed for them to "catch" (cut/grind ) properly even when new, and on the 320 or less grits, my belt is at a crawl. Sometimes on a bowie blade, I'll go through<stronge> 4 belts</stronge> on a single knife....

regards and good luck, mitch
 
Mitch pretty well covered it. I wish I could type that fast. I start with a rough 10" stone on a homemade grinder for the initial scale removal and rough shape. I like all the 3M belts. The 977 for the courser grits will pay for themselves. Im knee deep in worn out belts. Bruce B
 
CL, Mitch and Bruce.
Thanks for the suggestions. I finally threw out some worn belts the other day and will learn to pitch them routinely -- now.
I placed orders for some Norton, 3M and Klingspor in various grits today so I can try them all.

I had already replaced the graphite/canvas platen pad with 1/4" piece of glass and saw improvement. The glass has cracked but is still holding up well. I'll be ordering a spare platen to tap a piece of hardened 01 onto it next week.

Mitch, you mentioned you used up to 4 belts on one Bowie. This really surprised me and told me I can't get 4 knives from one belt.

I've taken to spraying WD-40 on the smaller grit belts and it seems to help keep the blade cooler and gives me a bit more control. Could just be me too.

I'll have to look around for a stone grinder to knock off the initial scale. Just like most, I'm running out of bench space.
 
I get my belts from:
Abrasives South
po Box 61809
Charleston,Sc. 29419
1-800-255-8112
I have had really great service from this company and there belts hold up really great.Alex Daniels told me to use them as he has been using them for years.
I also stop at 320 grit,but I do lightly polish the blade before hand rubbing with a dull 320 grit belt.But with light pressure only.I am using a hardened steel platen also.
I start with a 4 inch angle grinder to knock off the scale then start with 60 grit,then 150 grit then 320 and finish with a dull 320.This is the only dull belt that I will use as the others will take forever to grind and not leave a good grind.This is the teqnique that Alex uses and since he has been coaching me I figured that I would use his way of grinding.He starts his hand rubbing at 600 grit after the dull 320 grit.I haven't been able to get that clean of a grind yet but I am working on it.I do start hand rubbing at 320 just to make sure I have the grind cleaned up then do most of the work with 400 grit.
I'm rambling I think,
Bruce

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Bruce Evans Handcrafted Knives
The soul of the Knife begins in the Fire!!!!!
Member of,AKTI#A000223 and The American Bladesmith Society
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If you go to a neoceran glass piece It will do a great job for you and really last. Attatch the neoceran with either some silicon or two layers of carpet tape the type that is very thin without the fabric in it . Frank.
 
Hey TMICKLEY- welcome to the forums!

Mike is right- the neoceran is the way to go for the platen. It is available at most larger glass shops, who use it for fireplaces.

The platen on my Grizzly was not flat- which caused the glass to break under pressure. I had mine ground flat, used JB Weld to secure the neoceran, and am running the heck out of it with no problems. It was worth a little extra fuss to get the platen working smoothly.

Good luck and happy grinding!
 
The glass cracked on my platen during the set up from being uneven also. I asked the glass shop for neoceran initially and they hadn't heard of it so I settled for plate glass.
I'll look around again for neoceran now that I have a better description of what it is used for and do it right this time. Thanks.
 
I agree with most of everything that has been covered but when you get down to a finner grit,there is a trick that i found works well,I throw most all my worn out belts
but I uses a supper worn out 400 grit sprayed with TFL 30 and grind the hollow or flat with that it is probably equal to a 800
grit.RW Wilson told me about that trick you can come off a the belt if you have gotten all the scratches from the other belts and go
wright into buffing or hand finish,it only takes about 5 minutes to buff to a mirror
finish,first a sisalla wheel grey compound
then to a medium felt wheel with dark green
coumpound K@G them to a swien buff or air way wheel with white compound and then to a sewn buff with scrathless pink.run the sisalla wheel at 1725, and the hard to medium at 3450 and the last to at 1725 let up on the pressure on each wheel,you will be surprised what it looks like
 
OK, an update on my grinding problem. Took a new blank, same steel and basically the same profile. I used all fresh belts starting with 36 to 60, 120, 220 and ended up with 320. The 'deep marks/ripples' didn't come until I hit 320 grit and then went away quickly when I eased up on pressure on the blade to not have the butt joint 'knock' on the platen. Success! Thanks to all that chipped in.
Tracy
 
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