Notifications
Clear all

Belt Grinder Questions

9 Posts
5 Users
0 Reactions
2,294 Views
Posts: 145
Estimable Member Apprentice Bladesmith (5yr)
Topic starter
 

I just purchased a KMG grinder, which I'm very excited about. I have a couple questions that I hope folks will help with--I appreciate all input, and I'd like to thank you in advance.

1) What do you use (if anything) to surface the flat platen? Do you just grind directly on the flat platen plate, or do you cover it with something? I have only used grinders without a covering, but I understand that some folks do it differently.

2) What combination/series of belts and grits do you use? I've used 36 grit Cubitron belts before for the rough grinding, and liked them. Any other suggestions about the grit sequence and the types/brands of belts?

3) Also, where do you get your belts (supplier)? I anticipate buying several boxes of belts to get started, and I might as well start out on the right track.

Again, any advice is appreciated.

Steve

 
Posted : 15/05/2014 9:08 am
Robert Wright
Posts: 425
Member
 

Steve,

I would recommend adding a glass platen. It makes it grind cooler, and provides a smoother surface. Some use a tool steel platen. Several suppliers provide the glass platens in various sizes. You'll probably have to cut it to length. I use a disc cutter and just go slow. Be sure to wear a mask and eye protection, long sleeves, gloves, etc... I wear a face shield. Glue it on with JB weld. Be sure and plug the screw holes with grease before gluing.

I start with 60's and go to 120 before heat treat, but I also use a disc to keep it flat. After heat treat I'll use a Trizact belt A45 or 65 to clean up the plunge lines. Then a 120 j flex on the profile. Then it's back to the disc. I use Brownell's anti scale powder prevent scale. Really cuts down on the grinding.

I get most my belts from Pop's. He also carries the glass platens.

I get my sheet paper from Super Grit? I think that's what it's called. 80-2000. I just trim it to the disc after gluing them on. I use the trim scraps for my hand finishing.

Check out Steve Culver's web site he has all sorts of jigs to make life easier with the KMG.

Hope that helps some!

Bob

 
Posted : 15/05/2014 4:36 pm
Robert Wright
Posts: 425
Member
 

Guess I should have added, I do use 36's on occasions to profile when needed.

 
Posted : 15/05/2014 6:07 pm
BrionTomberlin
Posts: 1675
Member
 

Steve, I use the regular platen. Of course I have to resurface it every now and then. I do have a leather cover for it for special purposes. The KMG rotary platen does the same thing. For belts, most of mine come from Pops and Uncle Al at Riverside machine in DeQueen Arkansas. I normally use 36 grit for profiling and scale removal, then a 60 grit for grinding. Usually klingspor blue belts or the norton and 3m belts. Blaze and 3m 967's. I take my blades to 120 before heat treat and use 120 klingspor j flex for the final before heat treat grind. The j flex belts get in plunges real well. After heat treat back to 60 grit, usually the blaze or 967 to get everything right. Then from 120, 220, 400, before hand finishing. I like the j flex and trizact belts.

Brion

Brion Tomberlin

Anvil Top Custom Knives

ABS Mastersmith

 
Posted : 15/05/2014 7:55 pm
Posts: 181
Estimable Member Apprentice Bladesmith (5yr)
 

I have been following this thread and thought I would jump in. I have taken my knives up to 400 grit prior to HT. After HT I have been hand sanding instead of using a belt. I have not used the belt grinder after heat treat as I been worried impacting the heat treatment. Am I over worried about nothing or are you dipping the blade more quickly?

 
Posted : 15/05/2014 9:54 pm
Posts: 0
New Member Guest
 

Scott, if you grind bare handed you won't have to worry about messing with the temper. The blade gets very uncomfortable to hold long before you hit the 400deg or so that we usually temper at. I typically give the blade a quick dip every other pass which keeps it nice and cool.

 
Posted : 15/05/2014 10:49 pm
Posts: 181
Estimable Member Apprentice Bladesmith (5yr)
 

Thanks Justin. I can be a little retentive about things like this as I don't want to ruin anything mid-stream. This will make cleaning up after HT a little easier.

 
Posted : 15/05/2014 11:06 pm
Posts: 145
Estimable Member Apprentice Bladesmith (5yr)
Topic starter
 

Thanks for the information--I just ordered a bunch of belts from Pop's.

Here is a follow-up question. I know the answer to the following question depends on many factors--the quality of forging, how soft (annealed) you're able to get the blade prior to grinding, the amount of scale on the knife, the size of the knife, the amount of steel you leave on to grind off...but I'll ask anyway: what is your investment, on average, in grinding belts per knife (let's say, for a 7 inch blade fighter)?

 
Posted : 16/05/2014 12:57 pm
Robert Wright
Posts: 425
Member
 

That is a hard one to answer. I use a belt until it doesn't cut well, then retire it for wood working. A worn belt that's not cutting will make mistakes easier. Using an anti scaling powder during heat treat will make the post heat treat clean up a lot easier.

Bob

 
Posted : 16/05/2014 2:06 pm
Share: