Please help me. I just started stock removal knife making. I purchased belts from Pop's and he sent me 60 grit zirconia, 220 grit AO, 400 grit AO and 800 grit AO. I can get a nice flat grind finish in the 220, but when I go to either the 400 and especially the 800, the belt seems to clog really fast and grabs the blade leaving BIG marks. I slowed the belt speed down, but am still having problems. Any suggestions?
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fine grit belt frustration?
- Thread starter 69camaro
- Start date
- Joined
- Jul 27, 2003
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- 5,699
Use 36, 60, 120, 220 and then finish by hand sanding.
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- Aug 1, 2000
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- 863
This is one of the biggest benifits of the Rotary Platen Attachment. It is truly an amazing finishing tool...especially with the finer grit belts. It eliminates the "thump" and gouge caused by the belt seam.
If you ever get up to Columbus, feel free to stop by the shop where you can play with one as much as you would like. Bring some blades...and maybe some belts in case I don't have what you normally use.
If you ever get up to Columbus, feel free to stop by the shop where you can play with one as much as you would like. Bring some blades...and maybe some belts in case I don't have what you normally use.
- Joined
- Feb 5, 1999
- Messages
- 1,068
You may not be taking enough off at each grit after 60. It's a big step from 60 to 220, so you might try some 120's or 150's.
Spray some WD40 on the back of the belt so it slides over the platen easier, if you are flat grinding. Then make sure you are well into the grinder with your body, elbows locked to your sides That will take the bobble out of things and keep your grind lines straight.
If your belts are clogging really badly, they may be cheap belts and you'll have to upgrade. Grabbing is usually the sign of a used up belt when we try to get the last bit of performance out of the belt but already have. You hit a point where you have to put a new one on and throw away the old belt. We all hate to do that, because belts can be a sizeable investment.
The investnebt has to be contrasted against a messed up grind line that you have to spend more time fixing, or the possibility of injury and lost time from making as a result.
In my experience, when the belt starts to grab, it goes in the trash, period. I'll keep used up belts around for profiling or cleaning up a profile, but that's it.
Should you try 36 grit, they eat steel in a hurry. They also leave deep grind lines that you will have to grind out with another grit. Go easy on 36's. Leave lots of room to go at the blade with other grits. If you profile with a 36, always clean it up with a much finer grit before HT. The 36 can leave a deep enough grind line to cause a stress riser that results in a broken blade. Treat them with respect. A 36 will eat skin awfully fast, too, should your work slip.
If you are grinding to 600 prior to HT, you may be wasting some time, too. Depending on the steel you may have to drop back quite a bit befire you can break through the discoloration from HT. Watch your heat when using 400 and 600 grit belts on finsihed blades. The finer the grit, the faster the heat build up.
Perhaps the solution to your problem is in there somewhere.
Gene
Spray some WD40 on the back of the belt so it slides over the platen easier, if you are flat grinding. Then make sure you are well into the grinder with your body, elbows locked to your sides That will take the bobble out of things and keep your grind lines straight.
If your belts are clogging really badly, they may be cheap belts and you'll have to upgrade. Grabbing is usually the sign of a used up belt when we try to get the last bit of performance out of the belt but already have. You hit a point where you have to put a new one on and throw away the old belt. We all hate to do that, because belts can be a sizeable investment.
The investnebt has to be contrasted against a messed up grind line that you have to spend more time fixing, or the possibility of injury and lost time from making as a result.
In my experience, when the belt starts to grab, it goes in the trash, period. I'll keep used up belts around for profiling or cleaning up a profile, but that's it.
Should you try 36 grit, they eat steel in a hurry. They also leave deep grind lines that you will have to grind out with another grit. Go easy on 36's. Leave lots of room to go at the blade with other grits. If you profile with a 36, always clean it up with a much finer grit before HT. The 36 can leave a deep enough grind line to cause a stress riser that results in a broken blade. Treat them with respect. A 36 will eat skin awfully fast, too, should your work slip.
If you are grinding to 600 prior to HT, you may be wasting some time, too. Depending on the steel you may have to drop back quite a bit befire you can break through the discoloration from HT. Watch your heat when using 400 and 600 grit belts on finsihed blades. The finer the grit, the faster the heat build up.
Perhaps the solution to your problem is in there somewhere.
Gene
- Joined
- Feb 5, 1999
- Messages
- 1,068
Good belts and WD40 eliminate seam thump as well, for a fraction of the cost. Breaking the edge of the belt eliminates gouging, at no cost whatever. I'd rather use the money to buy something else for the shop.
Gene
Gene
Lot's of different approaches to this. Gene already made the point but going from 60 to 220 seems to be a big jump. You might try 120 in between. Use Norax belts above 120 grit and save the AO for wood or other handle material.
Last, when a belt grabs, it's normally worn out and needs to be pitched.
Last, when a belt grabs, it's normally worn out and needs to be pitched.
- Joined
- Oct 3, 2002
- Messages
- 12,297
Flat grinding is hell on belts. I start with a 60 ceramic, 120 yellow Klingspor, 400 yellow Kingspor, then hand sand. I also really slow the speed down on the finer grits, variable speed is a must for flat grinding. On my big knives, I use a new 400 on each side, (2, 400 belts per blade) then throw them in the trash. I get all my belts from Pop's, ask for the best belts not the cheapest.
I'm going to try one of those rotory plattens one day, wont give a true flat grind but more of a slight convex grind, this could be good though.
I'm going to try one of those rotory plattens one day, wont give a true flat grind but more of a slight convex grind, this could be good though.
- Joined
- Jul 8, 2001
- Messages
- 3,623
Here's a couple suggestions, go to gator 400 grit belts, they last and last and last. Then pad your platen. I use a piece of 4-5 oz leather on mine, its just there to soften and make the belts more forgiving. Once I get to a good clean 600 grit on the grinder,I hand sand to 2500, doesn't take long.
Good luck,
Bill
Good luck,
Bill
Don't expect the same belt life from the finer grits that you get from the coarser ones. You may grind 10 or more blades with a good quality 36g ceramic belt and still keep it around for profiling or rough work. If you get much more than 4 blades out of a good quality ceramic 220g belt, you are pushing the limit. 400 and 600g A/O belts do nice work, but they don't do it for long.
Be careful about padding the platen or using the rotary platen attachment. They are fine for a convex edge but will round out flats. If that's what you want great -just be aware of it. It can cause problems with fitting scales or areas you want flats with well defined edges.
Rob!
Be careful about padding the platen or using the rotary platen attachment. They are fine for a convex edge but will round out flats. If that's what you want great -just be aware of it. It can cause problems with fitting scales or areas you want flats with well defined edges.
Rob!
You could also try a belt/wheel rubber abrasive cleaner, sometimes called grinding belt dressers. I use these to extend the life of the belts. The rubber unclogs the belts and work just like a pencil erraser. Turn on belt sander and apply light pressure for a few moments, and you are good to go again.
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- May 3, 2004
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- 979
This may sound a little silly, but it sounds to me like you are pushing too hard and not letting the belt do its job. I use quite a bit of pressure when grinding with the 60 grit belts, but on the finer grits I use a soft hand. I just use a steel platen with no backing and I generally get 4-5 times the life out of the finer grit belts than I do the 60 grit ones.I really can't remember the last time I had a blade catch, if ever.
Thanks,
Del
P.S. I only use AO belts
Thanks,
Del
P.S. I only use AO belts