Slow speed belt sander

[Leigh Betsch]

Anyone ever use a slow speed bench top belt sander to sharpen chisels and plane irons? I'm thinking that a slow speed precision belt sander would be a lot better than a Worksharp because you would have a lot more abrasive material in a 30" or 40" belt that a 6" dia disk. I've seen belt sanders for grinding knives but I'm envisioning a much slower moving belt that would be more like a lapping machine. I know that you can buy diamond polishing belts for superfinishing all the way down to 50,000 mesh. I'm contemplating building one because the ones I've seen are pretty crude. I'm just wondering if anyone else has tried this and if there are pitfalls that I haven't considered sharpening with a belt. I'm thinking that the belt has to be in fairly high tension because a wrinkle would dub the edge, it should be water proof so you can wet sand, the platen should be lapped flat, probably variable speed or at least have a step pulley so you have several speeds to choose from.....any other ideas?

[Cliff McNeill]

I have to admit I too have been wondering the same thing about something slower enough to try some lapping on. Anyone try it yet?

[Alan Zenreich]

I've been using a variable speed 2"x72" belt grinder to sharpen my turning tools and plane irons.

This grinder has an 8" wheel, or I can switch to a flat platen. I have belts ranging down to a couple of microns

Sorby has a sharpening machine based on a sanding belt... same idea on a smaller scale.

[Eric Brown]

Belts don't last long and you still might never achieve the flatness that stones provide. Also, the speed of sharpening with power also increases the risk of burning the blade. Add up the cost of belts and consider the time to install them and you will probably fine that stones are cheaper in the long run. Personally I like the quiet and satisfaction of sharpening by hand. I use both sandpaper on a granite surface plate and the Shapton waterstones. I use honing guides. Just starting to get into edges with shapes (like gouges, etc). Got the new DMT Diamond Wave 1200 from Woodcraft but have yet to use it. I'll try it out tonight.

Eric

[george wilson]

I also have a variable speed 2' X 72" belt grinder- the Wilton Square Wheel grinder. I added a variable speed C face motor myself,because the grinder is already expensive enough. Surplus Sales (Right name?) used to sell a bargain 1 1/4 HP variable speed motor and control. Actually more powerful than the 1 hp. you can pay 2X for.

The slow speed comes in handy when I am making knife blades,and the slightest mis -step will produce a divot in your 95% finished blade. I am a nervous old man!

I have to say that it is not possible to get a belt tight enough to not have a SLIGHT rounding of the top edge of what you are grinding. It is only very slight,but as said,only finishing on a stone will give perfectly square edges.

The belt grinder is great to have,because it will remove metal more efficiently than anything else I have.

There are other belt grinders that run twice as fast as mine,and they cut incredibly fast. I think mine runs 4200 sfpm. the fastest ones run about 8000 sfpm. I saw a guy take a 2 1/2" angle iron at a machine show,and cram it against one of those fast grinders. I think in about 5 seconds he had ground the angle iron off to a 45 degree angle!!!

I ,being old and tired,don't care if the belts last real long. I use the blue zirconia ones,and they last me pretty well. I need all the help I can get! I sometimes lightly drag a diamond dresser across a 36 grit belt to sharpen it up a bit. It makes the belt reasonably sharper,but not new. Just a tip. Don't cut through the cloth!

[Leigh Betsch]

Thanks for the input. I've got to travel for business for a few days but when I get back I think I'll get to work building a slow speed belt grinder-sander-lapper. Might take me a while but I've got a design kicking around in my head. George, I found a web article where a guy built a grinder like the Wilton Square Wheel one, he did a very nice job but I'm thinking a more simple and more precision one. Alan where do you get your fine grit belts? I work for 3M and 3M makes diamond belts for super finishing all the way down to 50,000 micron but not at the plant I'm at. So unless I can find some seconds for sale in the company store (not likely) I would end up paying full price from a retailer and the diamond belts are very expensive. George do you slow your grinder down and lap with it or do you just use it to rough out the blade?

[philip marcou]

I also have a variable speed 2' X 72" belt grinder- the Wilton Square Wheel grinder. I added a variable speed C face motor myself,because the grinder is already expensive enough. Surplus Sales (Right name?) used to sell a bargain 1 1/4 HP variable speed motor and control. Actually more powerful than the 1 hp. you can pay 2X for.

The slow speed comes in handy when I am making knife blades,and the slightest mis -step will produce a divot in your 95% finished blade. I am a nervous old man!

I have to say that it is not possible to get a belt tight enough to not have a SLIGHT rounding of the top edge of what you are grinding. It is only very slight,but as said,only finishing on a stone will give perfectly square edges.

The belt grinder is great to have,because it will remove metal more efficiently than anything else I have.

There are other belt grinders that run twice as fast as mine,and they cut incredibly fast. I think mine runs 4200 sfpm. the fastest ones run about 8000 sfpm. I saw a guy take a 2 1/2" angle iron at a machine show,and cram it against one of those fast grinders. I think in about 5 seconds he had ground the angle iron off to a 45 degree angle!!!

I ,being old and tired,don't care if the belts last real long. I use the blue zirconia ones,and they last me pretty well. I need all the help I can get! I sometimes lightly drag a diamond dresser across a 36 grit belt to sharpen it up a bit. It makes the belt reasonably sharper,but not new. Just a tip. Don't cut through the cloth!

At last-someone who knows and appreciates the differences between a belt sander and a belt grinder.
I think a full-on knife making belt grinder is an asset in any woodwork shop as it is so useful. If it has also has a speed range to cope with different materials and differing contact wheel diameters this is even better.
Why do folk seem to want to slow grinders down?Bench grinder vitrified wheels work most efficiently at the peripheral speeds stipulated by the manufacturers (who know best), same for coated abrasives (belts) but these have a wider speed range-and run cooler. Simply the best for shaping and sharpening turning tools-or simply removing metal fast as already said.
I "came into" literally a truck load of belts in the early eighties- the accountants had decided that there was some "obsolete stock".... I am still using some of these now on my home made belt grinder, having brought them with me to NZ.
Want a matt finish? change contact wheel to a soft one. Want a mirror finish? Change to a hard contact wheel-all using the same belt....

[george wilson]

Leigh,you can only get a certain level of finish with a belt. Beyond that, I use wet or dry paper lubricated with soapy water(not TOO soapy) to produce a truly mirror finish.

I have gotten into using my Porter Cable reciprocating detail sander(senior moment! The one that takes the black rubber inserts for doing moldings) with wet or dry paper stuck on with adhesive spray. It works pretty well for hollow ground knife blades. It is very controllable,and doesn't sluff off crisp corners like just buffing does.

I have too much back trouble to hand polish forever anymore.

The variable speed Wilton square wheel bely grinder is rather ugly,but it is the most versatile grinder out there. You can very quickly switch from flat platen to 8" wheel,to small diameter drums(all running behind the belt) for different uses.

They cost a bit,but we had 1 at work,and it was the most used machine in the shop.. The blacksmiths used to come over and flatten the steel bits in their plane irons with it.

Everyone needed to grind something,from chisels to broad axes. I have 1 at home too,and use it for grinding metal lathe bits and kitchen knives-everything in between.

YOUR QUESTION: I have bought belts from Klingspor,MSC co.,and more recently on ebay-a lot cheaper. There's a person named Barbcat (kat?) who sells belts,good ones. I haven't noticed her lately,but haven't been looking too much as I am loaded with belts.

Only get the butted belts with the little mylar tape joining them. They have no bump,and lap joined belts don't seem to store very well,even in my controlled shop. They fall apart. The butted ones don't seem to. That mylar strip is magic!!!!!

P.S.-Be careful of those micron belts. They fly apart violently,and could cut the devil out of you. NEVER present a knife edge with the edge upwards to one. Those belts are VERY dangerous. You'll get a violent BLAM!!! when the belt explodes.

[Ron Petley]

I have a Coote 2X72 for knife making, great thing to have.
However, yes you can buld one lots of people do, their is a websit where pople post photos of the grinders they have built which would give you lots of ideas, maybe someones else can list it.
Sunray has inexpensive wheels, good contact wheels can get expensive.
Cheers Ron.

[Danny Burns]

Derek Cohen's site:

Mark I

http://www.inthewoodshop.com/WoodworkTechniques/BeltSanderGrinderMkI.html

Mark II

http://www.inthewoodshop.com/WoodworkTechniques/BeltSanderBladeGrinderMK%20II.html

Home Page:

http://www.inthewoodshop.com/

[Leigh Betsch]

That Coote looks close to what I'm looking for. I'm going to get my design worked out and estimate the cost to build it. I'm thinking I can build one cheaper but if it's close I'll probably spring for the Coote.
George, I'm thinking that the belt should rotate up so the chisel edge doesn't dig in a catch the belt causing an exploding belt. I think this would also reduce the dubbing. Any thoughts?

[george wilson]

Definitely don't rotate up. You want that steel dust going down,preferably into a vacuumed dust chute. I have a dedicated vacuum for my belt grinder. Never put sparks into a wood dust collector system.

Steel dust,and belt grit dust are most definitely not what you want to be breathing. Ai the least,have a container of water large enough in length and width to catch the swarf. But,do try to vacuum it if you can.

I got lucky and found a used Delta dust collector with about a 10" or 12" impeller mounted on top of about a 40 gallon drum. It is all factory stock. It has a cloth bag going out 1 side. To catch anything that gets through the bag,I have it next to a exhaust fan in the wall,with shutters that close when the fan is off.

The main wood dust collector's filter is also right in front of another such exhaust fan. I got sick in the early 60's teaching 6 periods of wood shop with no dust collector. It made my lungs susceptible to bronchitis for years afterwards. I don't want to add lung cancer to that!

[Leigh Betsch]

Actually I am thinkng about making it a horizontal sander. I guess my real thought is to make the belt so it would lap from the back to the front of the chisel. I not sure if this is clear.

I added a sketch
changed it to a jpeg, try that

[Glen Evans]

What are the main benefits of the 72" belt length over a 42" belt? Cooler cutting?? I've been looking at the Lee Valley system item number 68Z75.01 for making carving and marking knives...seems like a pretty cheap entry point but I don't know enough about it to decide--any thoughts?

Thanks
Glen

[george wilson]

Can't open your attachment.

Glen,are you talking about a 1" X 42" ? the long belt is 2" X 72". Will last a lot longer,much more abrasive area.

[Leigh Betsch]

I changed to format, give it a try now

[Glen Evans]

George, yeah I'm talking about a 1" x 42" unit. From your comments I conclude that the smaller abrasive area of the smaller belts would reduce their life (that makes sense). Are there any other downsides I should know about??

thanks
Glen

[Ron Petley]

As George mentioneb the belt on knife grinders moves in the other direction, the blade does not dig into the belt.
I just did the bevel on 8 plane blades no problem.
What you need is a good platten, a very flat smooth backing for the belt where you are grinding, some people use a glass plate. 2X27 belts come in the most types used for steel, including cork. The longer belt also runs cooler and lasts a little longer. In fact you would be amazed how long a GOOD 2X27 belt lasts if used properly.
Cheers Ron.

[george wilson]

Ron,Do you mean 72,not 27?

[george wilson]

On my Square Wheel grinder,the platen is cast iron,and years ago cost almost $100.00 to replace. It doesn't take too many month's use to develop a divot across the cast iron right above the tool rest. I developed the practice of making a steel plate out of fully hardened,and not drawn A2 steel to screw onto the original platen.4 flathead screws,one in each corner are drilled and countersunk into the A2 steel before it is hardened. The cast iron platen is also drilled and tapped to receive the screws. The screws are not where you use the belt,so pose no inconvenience. When the A2 is fully hardened,it is about 65 R.C.,or as hard as a file. It has chrome in it,and wears much longer than the cast iron.

When the A2 plate does get worn,I turn it over,having countersunk the plate from both sides.

A2 has to be hardened inside a stainless steel envelope. I add some Kasenit to add even more carbon to it to make it even harder.

The best grinders I have seen are for grinding auto window glass,and have a carbide platen behind the belt. I think they are made by Hammond.They are huge,and not easy to find,though.

[Wayne Morley]

Another very good and versatile abrasive belt grinder (also known as a polishing machine) is made be Stephen Bader. They have a floor machine that uses a 132” belt and a bench model that uses a 72” belt. They also sell all kinds of attachments and contact wheels. There web site is http://www.stephenbader.com/

I agree with what another person said about the belt speed. You will get better results and longer belt life with speeds in the 3500 to 10,000 feet per min. range.

As far as belt life goes most people replace the belt way before it is used up. I ran a polishing shop for about 12 years and I found that you could turn 10 pounds of brass into dust with one 120 grit belt 132 inches long by 1.5 inch wide.

All of the advice that George Wilson gave is very good, I would like to emphasize that an abrasive belt grinder can be a dangerous machine. You can get a serious and painful cut by bumping the edge of a belt going 8000 ft/min. Use proper safety equipment including gloves, safety glasses and a dust mask or respirator.

[george wilson]

Nonsense,Wayne. I NEVER got burned on a belt.:)

Actually,I'm lucky I didn't get severely slashed by a thin mylar belt. I had a few violently blow up.

[Dave Lehnert]

You can find a Shopsmith and belt sander for cheap on craigslist.

You can slow the belt way down. and change the belt direction by mounting on the opposite end.

http://www.shopsmith.com/ownersite/catalog/images/01_BeltSander.jpg

[Leigh Betsch]

I saw one of these Shopsmith belt sanders for sale somewhere but I didn't know if it would be easy to attach an electric motor, so I passed on it. How is it driven? Would it be difficult to attach an elelctric motor, keeping in mind that I'm not much of a welder but can do a pretty decent job of machining.

[Dave Lehnert]

I saw one of these Shopsmith belt sanders for sale somewhere but I didn't know if it would be easy to attach an electric motor, so I passed on it. How is it driven? Would it be difficult to attach an elelctric motor, keeping in mind that I'm not much of a welder but can do a pretty decent job of machining.

It would not be hard at all to mount it on a stand. Shopsmith makes a "Power stand" but not too sure how slow it would run.
http://www.shopsmith.com/ownersite/catalog/images/01_PowerStandsGroup.jpg
Some people are buying old Shopsmiths and cutting them down to make a mini to run tools.

http://www.shopsmith.net/forums/image.htm?u=1010&dateline=1206644762

[Alan Zenreich]

I too have a Bader III 2x72" variable speed belt grinder that I use for sharpening chisels. I have both an 8" wheel and the 'knifemakers' flat platen/wheel combo.

I currently have it configured with a Nova Sharpening Center (from Teknatool)

I'm also experimenting with final honing/touchups using scary sharp method on plate glass.

[george wilson]

You do grind bevel upwards into the direction of the rotating belt with norman cloth backed belts. Just do not try it on those paper thin mylar belts.

If you don't grind with the cutting edge upwards,you can't tell how thin your edge is getting.

[David Martino]

Interesting discussion... I have a 3x21 Bosch belt sander (portable, not benchtop) that I was thinking about using as a grinder for chisels, plane irons &c. The sander has a clamp attachment for clamping flat or vertical on a bench, and also a fence attachment. Any tips or things I should watch out for?

[John Schreiber]

Interesting discussion... I have a 3x21 Bosch belt sander (portable, not benchtop) that I was thinking about using as a grinder for chisels, plane irons &c. The sander has a clamp attachment for clamping flat or vertical on a bench, and also a fence attachment. Any tips or things I should watch out for?
I've done this for rough sharpening. I use it in place of a grinder to get nicks out of a blade or to change a bevel angle. It doesn't get as hot as quickly as a grinder, but it can still burn a blade. I keep a bowl of water near by to dip the blade into so that it doesn't get hot.

I have some wooden 25° and 30° angled blocks which I use to keep the blade at the right angle. I'm not fully satisfied with that system though.

I still hone the blades after use, but it seems to be a real improvement on a grinder.

[george wilson]

Contaminating your belt sander with steel dust may come back to bite you. If you haven't truly gotten rid of the steel dust and get it on your wooden projects,any water or water based stains,fillers,etc. will give you indelible blue (on oak) or brown spots that you will find a chore to remove.

[philip marcou]

Has anyone tried out the 3M Trizact diamond belts and if so what is the verdict?

[David Martino]

Contaminating your belt sander with steel dust may come back to bite you. If you haven't truly gotten rid of the steel dust and get it on your wooden projects,any water or water based stains,fillers,etc. will give you indelible blue (on oak) or brown spots that you will find a chore to remove.

Hmm, hadn't thought of that. Maybe dedicated belts for wood vs. metal?

I have heard you'd want to be careful of grinding some metals together - aluminum and steel or iron? - because the combined filings can be explosive...

[Wayne Morley]

Has anyone tried out the 3M Trizact diamond belts and if so what is the verdict?


I have used them, and for some applications they are very good and the extra expense is worth it. The main problem with this product is that it is pressure sensitive. By that I mean, if you apply to much pressure when grinding you will strip the abrasive off of the belt and ruin it. It is not what I would call a general purpose abrasive. I wouldn’t bother with it unless you have a specific, high volume, application in a manufacturing environment.

[philip marcou]

I have used them, and for some applications they are very good and the extra expense is worth it. The main problem with this product is that it is pressure sensitive. By that I mean, if you apply to much pressure when grinding you will strip the abrasive off of the belt and ruin it. It is not what I would call a general purpose abrasive. I wouldn’t bother with it unless you have a specific, high volume, application in a manufacturing environment.
Thanks Wayne. I was given pieces of belts by a merchant to use by hand or in the lathe , for metal working and found it to be disappointing, so possibly it only works well when used at high speeds as in a belt grinder or dedicated sanding machine.