The difference a disk makes

Ok, I Should of set up my grinder months ago.... Wow.

I had a pretty good oops, from the edge of my 2x72 belt, you know.....2" in
I didn't think it was That bad, but it was. You could feel it with your finger ......

It's GONE.
Lickety Split.


With the large,flat surface, I can really twist and torque the handle pretty easy, pushing Down.
I'm able to walk my grind to the edge without worrying of rounding the top spine. Like I would with my 2x72.
 
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I really love having a KBAC for mine. I know there's cheaper alternatives out there, but I'd rather not skimp when it comes to that. Being able to easily control RPM's and also being able to toggle switch between forward and reverse makes it a much better experience for me.
 
Something I realized, with my extremely limited experience.
I have about 30 mins of play time on my disk grinder........

I find a bevel guide/file guide seems to really work well.
when I First started out I bought a bubble level guide, but stopped using it. I just freehand on my 2x72 without anything now. With the jig, It felt like I had too many things to pay attention to, and I felt distracted.

So recently, I decided to clamp the stop down on my blade for the disk. Wow, I can really, easily plow against the disk's spinning edge.
I Like that concept a lot now, and might look into a carbide file jig specifically for this. Or maybe I'll make a plastic version to glide against the rim?
 
thanks to this thread, I now have a functional disc sander! The motor is from the first 2x72 I got, which came to me in a trade for a knife made by Jason Knight. It's a single phase, 1750 rpm motor, with a switch installed. Pretty decent motor, but I didn't know it couldn't be hooked up to a vfd until recently. Awhile back, I bought a disc for it, thinking that hooking everything up the way I wanted would be easy. Never occurred to me to mount it horizontally, which I did today. I ran it for a bit to true up a tang, and man it's like the heaven's parted and the hands of angels reached down and blessed my tang with flatness!

Thank you, Shop Talk, for existing!
nv9b4bD.jpg
 
I don't believe that motor can be run on a VFD. It is a capacitor start motor. It should be single phase.
However, you should be able to wire the switch for forward and reverse with center off.
 
Stacy E. Apelt - Bladesmith said:
I don't believe that motor can be run on a VFD. It is a capacitor start motor. It should be single phase.
However, you should be able to wire the switch for forward and reverse with center off.
Click to expand...
reverse, you say? 🤔
 
weo said:
yep.
Kinda a necessity on a disc grinder so you can do both sides the same, not have to do one side edge up and the other edge down.
Click to expand...
what I really need it for yesterday is to true the tangs of three knives I'm working on, where I pretty much need to have a file guide on. There is literally no way to use the disc on one side without holding the knife in such a way as the rotation would propel it into my crotch. I have a reverse switch for my 2x72 vfd on the way, which will take care of the Brodbeck attachment, but I realize now that I need a switch for this thing too. Amazon, here I come!
 
A reverse switch for teh VFD is not what you want.
Look at the wiring diagram on the motor. It shows what the reverse connections are. Wire an ON-OFF-ON switch (DPDT center off) so you can switch from one to the other. Don't throw the switch from forward to reverse until the disc stops spinning or you can create a huge current spike.

Here is a basic diagram. It may or may not exactly match your motor:
1687689145958.png
 
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You could always set up variable speed using two step pullies and a belt, but at that point it's probably more worthwhile to just pick up a motor on ebay that you could hook up to a VFD! :D
 
Any thoughts from regular users on horizontal vs vertical mounting, is one more productive than the other?
 
DanF said:
Any thoughts from regular users on horizontal vs vertical mounting, is one more productive than the other?
Click to expand...
It depends on what task you do Dan . I have them four ................ Work rest on vertical mounting is MUST . Soft backing behind sand paper make wonder in some task . . .. .
 
REK Knives said:
Why not set it up so it can do both?
Click to expand...
Good and valid point!
For me, I hate changing out setups once I have them in place, hence four benchtop drill presses, a 2x72 with flat platen and one for a grinding wheel.
Always looking for a way to save a few minutes, when the minutes have become precious. :)
 
DanF said:
Any thoughts from regular users on horizontal vs vertical mounting, is one more productive than the other?
Click to expand...
Not regular use, yet.

I'm a product developer by trade, and I over think things by my nature.......

MY reasoning for wanting to set my disk up horizontal, instead of the more conventionally done (vertical) is because in my opinion it's easier to push down than push against.
it's very intuitive pushing down flat, compared to pushing vertical flat.

easier to see with your eyes to see flat, and easier with your hands. IMO.

*I have no intention of mounting a table/support on my disk. I bet most disk grinders are mounted vertically just for this "selling feature".

I'm using it to flatten blades, tangs, and handle material. I want flat, I don't care about perpendicularity. (In these steps)
 
Crag the Brewer said:
MY reasoning for wanting to set my disk up horizontal, instead of the more conventionally done (vertical) is because in my opinion it's easier to push down than push against.
it's very intuitive pushing down flat, compared to pushing vertical flat.
Click to expand...
How are you holding the steel while flattening on a vertically-mounted disk? I've seen some jigs built around magnets that seem like a good approach.

Also, does anyone know of a relatively low cost source for the disk? I was surprised at the expense of some of them. I'm sure they're good quality but I was thinking I might be able to put together a low-cost setup until I saw what Nielsen and others are charging. If I need to drop over $500 I might as well just save that money for a 2x72 instead.
 
dwaterfield said:
How are you holding the steel while flattening on a vertically-mounted disk? I've seen some jigs built around magnets that seem like a good approach.

Also, does anyone know of a relatively low cost source for the disk? I was surprised at the expense of some of them. I'm sure they're good quality but I was thinking I might be able to put together a low-cost setup until I saw what Nielsen and others are charging. If I need to drop over $500 I might as well just save that money for a 2x72 instead.
Click to expand...
Im not.
I have my set up mounted horizontally.
I freehand grind everything, I tried a couple jigs/fixtures on my 2X72, but they just didn't work out the way I wanted..... cumbersome.

I'm not sure what the advantage of those swappable Nielsen disks are?

I use 3M feathering adhesive. The stuff I posted in the pictures above.
I can peel and stick one grit, use it completely or just a bit. I can peel it off, and put another one on. Peel it off, and go back to the previous disk, back and forth, back and forth. It doesn't matter.
The disk stays sticky, the sandpaper doesn't seem to. all the stickiness stays on the disk.

*I recommend a 2X72 first, before getting a disk grinder.
 
Hey - great timing - let me know how it works. I also at some point in the near future I hope to invest in a 9" disc grinder. If at 2x72 attachment works great it seems like you could save some $ and space with at attachment. I have seen a few advertised but not sure if its worth it or not opposed to the devoted disc unit. Hope you can let me know what you experience.
Lorien said:
ordered a Brodbeck disc attachment for my 2x72, fingers crossed it'll work. Much cheaper than the real deal, and the speed is adjustable. Also ordered a reverse switch for the vfd.
only downside I can see at this point is no option for a work rest, but the main thing I need it for is to true up surfaces so it should be good for that
I have a single phase 1750 rpm motor which I bought a disc for, but it's way too fast for most things. I'm sure I'll find some use for it at some point
Click to expand...
 
Crag the Brewer said:
Im not.
I have my set up mounted horizontally.
I freehand grind everything, I tried a couple jigs/fixtures on my 2X72, but they just didn't work out the way I wanted..... cumbersome.
Click to expand...

So when you flatten are you working on part of the blank and then rotating and doing the other part? I'm concerned about chasing level if I do that instead of some way of doing the whole piece either at once or with a sliding jig of some kind. Maybe it's just something that takes practice.

Crag the Brewer said:
I'm not sure what the advantage of those swappable Nielsen disks are?

I use 3M feathering adhesive. The stuff I posted in the pictures above.
I can peel and stick one grit, use it completely or just a bit. I can peel it off, and put another one on. Peel it off, and go back to the previous disk, back and forth, back and forth. It doesn't matter.
The disk stays sticky, the sandpaper doesn't seem to. all the stickiness stays on the disk.
Click to expand...

I've heard people say that you cannot re-use a disk once you take it off. In woodworking, I've generally stuck with one grit since I only use a disk for a few things and those are well before I get to finer grits.

Since you're able to re-use, then I agree that maybe the Neilsen system isn't needed. The only advantage I can think of is saving time if you have several disks set up at different grits.


Crag the Brewer said:
*I recommend a 2X72 first, before getting a disk grinder.
Click to expand...
Yeah I had brief hope that maybe a cheap disk setup could bridge the gap a bit but sounds like it's not a good path forward for me.
 
D dwaterfield
*I'm currently just a Fixed blade maker. I've read that disk grinders are even more handy for folder maker guys, as they are fitting parts more often.
*I do all my grinding Post heat treating
*I mostly work on high alloy, Hard steels.


"So when you flatten are you working on part of the blank and then rotating and doing the other part? I'm concerned about chasing level if I do that instead of some way of doing the whole piece either at once or with a sliding jig of some kind. Maybe it's just something that takes practice."

Working on very hard steels is sort of forgiving. I can Grind and Grind, and Grind, and Grind.......... It's almost like nothing happens.
so it's easy not to screw up, because work is so slow.
Yes, I can redo, reposition, flip over, and start up again. I often go back and adjust my work/grinds.

I just have to change the direction of the motor on the disk grinder when I am working on the Other side of the blade. It's very important to be able to switch your motor in reverse. Quickly, and easily.
I just have to press a couple buttons.


Crag the Brewer said:
*I recommend a 2X72 first, before getting a disk grinder.
Click to expand...
"Yeah I had brief hope that maybe a cheap disk setup could bridge the gap a bit but sounds like it's not a good path forward for me."

-Not sure? Ive seen blades that look like their plunge was made with a disk grinder.
But, I bet that was done pre hardening...... Cause it's pretty slow to remove metal after hardening on a disk.
 
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