belt sander and thinning blades?

BJE

BJE

Joined
Apr 12, 2006
Messages
3,080
I am new to the world of power sharpening devices. I would like to regrind a few of my knife blades so they cut better and sharpen more easily. What would be the best and most cost efficient way of doing this? Also, are there any good instructions or tips for doing this? The hardest steel I will be working with is D2. I will mostly be working with blades under or right at 4in. long. Thanks for any advice.
 
If you want to thin existing blades - assuming flat grinds

You may prefer a disc grinder. It will be easier to maintain the existing angle.
Apply the blade to the disk at the angle, start & stop the disc with a foot switch while in contact.

http://www.beaumontmetalworks.com/

1hp-vs-disk.jpg


It's about 1/3 the price of a comparable 2x72" Belt grinder
As you can see, you may be able to fab this up yourself cheaper.
The Variable speed option is a must have. Lower speed gives less heat and more control.
The 9" disc allows you to use inexpensive flat sheets of abrasive paper and spray on adhesive.
 
Last edited:
Be extremely aware of heat build-up.
 
I am wanting to thin the primary grind, much like what Mr. Krein does to the knives people send him. I would like to do that for myself. I will be very careful of heat, but I don't think it will be that much of a problem. I have heard alot about the belt grinder from Harbor Freight, but I don't know if it will be big enough for what I am planning to do.
 
I dont see anything wrong with useing a small belt grinder (Im assuming you are speaking about a 1"X30" or something like that when refering to HF) well actually speed can be a problem with those little boogers... Make sure you read up on platens (something I have been meaning to do for a while! :) ) The platen on my grinder is serviceable but deff. not ideal. I believe I will be cutting a piece of glass and temp glueing it to the current platen.

Id also recomend a disk like Steven pointed out. Although mine is not variable speed and is only a 6" I have found it to be a very usefull grinder overall in my "shop".

Let me/us know what you end up doing and how it works out for ya! :thumbup:
 
I know it has already been mentioned, and you've already said you're aware of it, but grinding hard steel (especially something like D2) can generate heat quickly. And you only need to exceed the tempering temperature in one spot for one instant and you've moved your temper. The thinner you go the easier it is to do this. The magic number for many of my D2 blades is 450F. It won't even run a color to let you know you screwed up.

My "tip" is to find a groove where you grind, dip, grind, dip etc... Start with a course belt so it cuts with less pressure, so you generate less heat for the majority of the stock removal. Use belts like they are free, sharp belts cut cooler. Grind slow.
 
How difficult is this? I am pretty good with my hands, and I have some experience with a bench grinder, but I don't want to waste my money if it takes years of practice.
 
difficulty level ? Well it sure ain't what I would call easy. If it were a knife I really liked , I would pick up some cheap ones to practice on first. If it is something you think you will do over and over , then invest in the tools , if not , send it to Krein :)
 
I agree with John. You are not likely to get results like Tom (he is very good at what he does) without quite a bit of practice. However, if it is a skill you would like to acquire buy some tools and practice on some cheaper knives.

Allen
 
I'm as good with my hands as anyone, but my first few attempts went onto the scrap heap. It depends on your expectations. While I wouldn't say it is really hard to do a half way decent grind, you probably won't get there your first few tries.

It takes a lot of practice to get grinds good enough to sell. I don't think that is what you're after. If you're just wanting to thin out some blades for better performance, you can probably get "good enough" in a few attempts. Just don't be thinning out any $300 CRKs etc.
 
I'd be leary to re grind an already hardened blade with a 1x30.sure,many guys after heatreat including myself,but on a 2x72" with good ceramic belts.if you dont plan on seriously getting into knifemaking i'd send 'er to Tom!
 
I am not looking to do this for money, just for myself and maybe a few friends and family. How long does it take to remove that much metal on a power grinder? For me it takes about 30min. on a very coarse stone to thin out a factory edge to a satisfactory level. Are we talking about five or twenty min.? Which belts would you reccomend? I have been looking at the belts from lee valley, but can't decide between the blue zirconia or the aluminum oxide grinding belts. Thanks for all the help and keep it coming.
 
Any knifemakers in your area ? Chances are pretty good you could get someone to show you the ropes so to speak and perhaps even let you attempt it under their guidance , just so you can see if it is something you want to get into.

With the 1x30 belts don't last long , and while removing metal doesn't sound all that hard , keep in mind this is hardened steel. The finer grits are used for scratch removal , the coarse stuff for material removal ( and sometimes skin ;) ). The ceramics tend to run cooler.

I could never get a platen setup on the 1 x 30 that I was happy with. Plus that 1 x 30 is a screamer , it runs fast ! The 1 x 42 is pretty fast as well. I made one knife using a 1 x 42 and bought a Bader , with the 1 x 42 it seems all I ever got good at was changing belts. :)

Perhaps a better option is :
http://www.sears.com/shc/s/p_10153_12605_00921513000P

You can find it on sale often for $99

You mentioned heat shouldn't be a problem , believe everytone - the edge heats up fast , so a nice cold bucket of water and quench that sucker constantly.

And remember , its not just about removing metal , its removing metal EVENLY. Especially since your end goal is to make it cut better.

Warning though - once you get it going and find the satisfaction in doing it yourself. There ain't no turning back... soon you have drill presses , disk sanders , 2 x 72 grinder's , mill , lathe....etc. ;)
 
The other consideration is how uniform the edge will be when you reshape. If you are a little off you could have a hollow point or and area where the grind is uneven. For utility this would not be a problem but for looks may not be good. I have given away some finished knives because I screwed up the final grind.

You may want to try some good diamond stones. This will give you more control and can remove alot of hard material fairly quickly. Otherwise I use the slack belt on a 1 x 30, and finish sharpen with a leather belt with green polishing compound. Might as well get a good sharp edge while you are at it.
 
John T Wylie Jr said:
Warning though - once you get it going and find the satisfaction in doing it yourself. There ain't no turning back... soon you have drill presses , disk sanders , 2 x 72 grinder's , mill , lathe....etc. ;)
Click to expand...

AMEN TO THAT!
All I have to add to this is a few safty tips: wear those glasses, it's easier to work on knives when you still have both eyes.
Bucket of cold water is a necessary piece of equipment on any grinder.
HAVE FUN WITH IT! A few cheap knives to practice on is a good idea, you could even mess with re-shaping the blade profile after you have the edge thinned on them. Good luck and Happy Grinding,
Jeff W.
 
Ceramic belts as well as zirconim are available for the little 1x30 machine. JMHO good belts are more important than anything else.http://www.supergrit.com/products/products_belts-ceramic.asp
even with 2, 2x72 grinders I still find use for my smaller sanders. If you watch for a sale you can get the HF 1x30 for just over $20.00 http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=2485
I preferred a 4x36 woodworking sander over the 1X30 because of its slower speed, and it is more useful for other things.
 
Oh hey I was gonna mention... Everyone is saying "buy a few cheap blades to practice on..." I took that to heart when I first started and I believe in it, no doubt. The way I did it (always lookin for the most economical way ;) ) was to go to my local swap meet and buy a bunch of cheesy machetes! These give you plenty of edge to practice on and you can dedicate, oh say, 6" sections of edge for practice. I got some cheap ones that I did this with and then I found a brand new coldsteel bolo for a couple of bucks. I put a nice edge on that one and kept it for camping and whatnot.

Is there a way to slow down my 1"X30" just outta curiosity?

My Pop (he doesnt know what I really need) bought me a HF 4"X36" (I think) with the 6" disk and honestly between the 3 grinders I have been able to make some halfway decent knives.

My first regrind on a factory knife was changing a Ka-Bar tanto folder into a Ka-Bar clip-point folder :D This went very well asthetically but I believe I murdered the HT. Didnt matter thoughh because Im a sharpening junkie, I use the knife only at work on cardboard and enjoy sharpening it every night... really! I sharpen everyone in the factories knives. Its weird how little 'normal' people care about how dull their knives get! Jeez...

Anyway carry on...
 
what I am going on my 1 x 42 is swapping out the pulleys. Getting rid of the tiny 1" one in the front and the one in the back as well ( its a darn metric size ). Figured to get a much bigger one in the front ( gonna have to slot the chassis for belt clearance ). PLaying with the ratios I hope to slow it down 30-40%.

Just an idea ( mine is a delta , though if the Grizzly aint a metric shaft I may mod that one instead. )
 
Like everyone said PRACTICE on whatever you can get your hands on. After 30years a bader 2 square wheels and 5 9' discs I still trash blades more than I'm comfortable with.
Ken
 
You must log in or register to reply here.
Back
Top