What parts to build a disk grinder

rfrink said:
He has interchangeable plates that fasten to the main disks. this way when he changes grits, he simply changes the plate. His wall is full of different plates made from different materials...with different grits ready to use. No waste from using a sheet one time and tossing it. When done, just hang it on the wall until needed again.
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Rob, if you made a system like that, I would buy one.
 
Rob, we are talking about the one that uses the magnetic sheets to mount the paper to, aren't we?
 
Regarding the feathering adhesive. I bought a can of spray adhesive at Home Depot or somewhere like that, and yes it's sticky as all get-out. But reading the label I saw where it talked about a less-sticky alternative: Spray one surface and apply when it's just tacky, kinda like Mike said - it doesn't come off on the fingers. I tried this and if timed correctly it works very well. One caveat however - make dang sure it sticks all over the plate!

I had two variations of failure. One, the paper did not stick fully over the full surface. My grind was flaky and I got rounded edges. Two had more to do with not trimming the edge carefully than with the adhesive. There was a little hangnail of paper off one edge that I either didn't notice or considered too little to worry about...

I spun that baby up and was happily grinding away when BLAM! the blade went flying and my hands came away with a creepy numb feeling... When I assured myself everything was still attached I retrieved the blade and put a new sheet of paper on the disk and got back to work. With renewed respect for powerful objects spinning at high speed. :eek:

Done properly though it is easier to change sheets. This is good because I haven't quite figured out the "optimum" grit to leave on the machine for most tasks.

One thing that has helped me to grind vertically is that the table I made wraps part way around the sides of the disk. That way it serves as a rest when I'm grinding the flats of a tang or whatever. One thing to think about when building the table is its material. Mine is aluminum (the grinder having been built out of what I had laying around the shop, like many things :) ), which is a bit "sticky" for sliding the knife back and forth over the disk. Steel would have been better because, I think, it would be "sliperyer". [Larsen mangles the language again]
 
I've had the same problem with Elmers spray adhesive Dave. My disks always launch at my head though.

I tried rubber cement once and it held well. Too well. I couldn't get it off. Took 2 hours to change the paper.

The other system I was talking about used a steel platter and sheet magnets that I bought at Ben Franklin. I mounted the paper to the magnets. Works fine on slower speeds. Higher speeds are an adventure.
 
3-M, feathering disk adhesive is made specifically for disks, and to make it easier to change the abrasive sheet without having to go to a lot of trouble.

Just follow the directions on the tube, or spray can, and you will be able to change abrasive in seconds. You can do this a few times before you have to clean the disk, and reapply the adhesive.

Again, any auto body supply paint store will have it.
It is also carried by K&G.
http://www.knifeandgun.com/catalog/adhesive_186655_products.htm
 
Thought I'd show a picture of mine too, as I'm pretty proud of it. :) All built out of stuff laying around the shop with the exception of the motor and controller of course. The motor is 1.5 hp which I got from American Science and Surplus (a gadgeteer's heaven) for $50 and the controller off eBay. I would not have been able to make the controller work without the highly skilled aid of our own Roger Linger, who figured out what was wrong with it and tracked down some esoteric part. Now it works like a charm. I am a lucky human, no doubt about it. :D

BFDisk01.jpg


One thing that was worth doing was to cut out an angle underneath the table to allow it to belly up to the disk when lowered at an angle. Without that the table surface would have been a quarter inch or more from the face of the disk. Took some grinding, filing and carefully chosen motivational language to get it just right, but I'm glad such a discplined worker. ;) Paid off.

The table slides out to allow room for changing paper, which was the part of this thread that got me going again. When I've used up that expensive can of adhesive I have now (shouldn't take long as I seem to use as much clearing the spray thingie as I do coating paper) I'm going to try Mike's feathering spray. That sounds like what I need.
 
peter nap said:
I have a bunch of disk grinders for different things. I made most of the platters but found recently that Woodcraft has them for 15.00. I have a couple now and like them. One day when I get off my butt, I'm going to order one of Rob's beveled disks.

John Leitch wrote and article in Knives Illustrated winter time last year about his disk system.
Rob, I tried this and have a problem with it. On very slow finish grinders it works OK but on my faster grinders, it launches a spinning steel Frisbee at me.

Anyway...I try to stay with 1 hp and larger motors just because I like big motors and scrounge them, I have enough grinders so I can switch grinders and grit without changing disks. I am going to try the 3m feathering adhesive. I have had a running battle with adhesives on the faster grinders,
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Hello Peter.

when you set up your grinder with this disk did you put the dowell in the center of the disk to hold it and keep it centered? I know John and when he was designing this we talked about it quite a bit. I have used this set up on a 1725 RPM motor for a long time and never had a problem, I dont know how it would work on a 3400 RPM motor. The nice part is you rarely have to mess with adhesives and you dont need a bunch of different machines. Take care and be careful.

Eddie Baca
 
Thank you Eddie. To be honest, I did not put the Dowel in. I had completely forgotten about it. This is one of those things that I read about and filed away in the back of my mind. When I finally got around to doing it, I didn't go back and reread it.

It makes sense that I would be having problems without it.

Thanks again!
 
Dave, I remember when you posted your disk grinder before, it was then and still is the prettiest disk grinder I have ever seen. I especially like the heat sinks. I went to see American Science and Surplus and got stuck for a half hour before I snapped out of it and came to. I have added that one to my favorites.
 
:D Tracy it's not so pretty anymore...seen lots of hard use! :D American Science and Surplus is a blast. Every time we get their catalog my wife and I fight of who gets it first. :D (She wins.)
 
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originally posted by ddavelarsen:
Ideally you'd be able to switch it (disc grinder) from vertical to horizontal. Vertical to do stuff like dovetail bolsters and scales; horizontal to flatten tangs and blades ... I'd sure like to have some input on how one might go about building it such that you could do this ... if one of you guys has an idea how to go about it and the Photoshop skill to draw it.
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Ask and you shall receive. ;) The attached picture is a method I modified from Wood Magazine's Idea Shop 3. They had a 2-machine cabinet with the fixed pivot rod in the middle of the platform (not toward the front as I show) and mounted seperate machines on each side of the platform. To switch machines, they just flipped the platform over & locked it in place with the locking pins on each side.

As shown, be sure your platform is wider than your disc or install stops (or a cabinet front panel) to keep the platform from over-rotating and jamming the back side of the disc onto the top edge of the cabinet sides, which could bend or break the disc. :(

If the picture doesn't convey the idea clearly, feel free to email me with questions.
 
Ha! And what's really nice about that is I could do it with my current machine with very little in the way of changes. Excellent! I may just give this a shot. It would mean a free standing machine that would also free up some bench space... Benefits, benefits. Since I've learned to do everything I've needed to so far on the vertical disk it may be a while before I build this, I've printed your diagram for happy future reference. Thanks a lot!
 
Phil it seemed like this may have gotten off track and there's one question we may not have answered fully. My setup is variable speed and the controller is reversible. This is most worthwhile as it allows you to switch working sides while maintaining the same orientation of the disk's rotation. eBay is a great place to find controllers but Steve Sando also has a source for inexpensive new ones. I can't remember that source but he'd be happy to direct you. Be sure whatever you buy off eBay is guaranteed to work! Mine didn't. Roger pulled my "rest" out of the sling on that one.
 
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