Disc Grinder Questions

slightly off topic here, but I was wondering if anyone would care to share their ideas/ideals regarding horsepower and RPM of the motor for their disc sander, particularly if no VFD is part of the equation
 
Crag the Brewer said:
@AVigil
Oh.... I think I get it now...

I was thinking/worried about going over the center (red line) that looks flat.

You are talking about the green area creating a spooned out area?



Makes total sense, Now.
I was thinking 2D....haha, not 3D I guess

*Very informative thread!
Thanks.
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I was going to add this to my picture too, thanks for saving me the trouble...
 
Lorien said:
anyone would care to share their ideas/ideals regarding horsepower
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I'm pretty sure I have a 3/4hp. I'm not pushing very hard into the disc so don't need the extra HP. I use it just to finish the flats, not hogging off material.

PS - Really off topic here, but do you still have/use the blade from the Wheeler's Steel WIP thread?
 
weo said:
I'm pretty sure I have a 3/4hp. I'm not pushing very hard into the disc so don't need the extra HP. I use it just to finish the flats, not hogging off material.

PS - Really off topic here, but do you still have/use the blade from the Wheeler's Steel WIP thread?
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haha, that IS off topic! The answer is yes and yes

I have a sealed motor that's 1.5hp and 1750rpm, from my olde frankengrinder, and it hadn't occurred to me that I could just buy a disc and slap it on there til finding this thread. Seems like with a good workrest the disc might also be good for profiling as well and flattenating?
 
Lorien said:
slightly off topic here, but I was wondering if anyone would care to share their ideas/ideals regarding horsepower and RPM of the motor for their disc sander, particularly if no VFD is part of the equation
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I have 1 hp which is likely more than necessary.
The VFD seems essential. I can set up and do the two sides of a swedge exactly the same thanks to reverse. I also vary the speed a little depending on what I'm doing.
 
N.W. Gean said:
I have been using my disc in this fashion for a couple months now. It is extremely useful for flattening tangs and scales, however, you find it troublesome to keep switching back and forth. As soon as I can pickup another motor to hook into my VFD, I will do so.

I bought mine from USA knife maker, but I am not sure if it matters as everyone seems to ask about 100 for theirs. I am using one with the 1 degree taper, but I don't have enough experience to say if it is good or bad. You can find many threads where it is argued for one way or the other.
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Glad to hear it has been working for you. I think Ill get a disc and see how long it is before I convince myself I can squeeze a dedicated motor into my shop.
 
Colby L. said:
Glad to hear it has been working for you. I think Ill get a disc and see how long it is before I convince myself I can squeeze a dedicated motor into my shop.
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You will probably tire of the change out in a short order. I didn't even use the disc for several months because of how difficult it was to pull the drive wheel off the motor until I found out I couldn't live without a disc grinder. Tip: use a bit of anti seize or some kind of grease when you put on the drive wheel so you can switch easier.
 
I'm getting really warm to the idea of having a disc grinder to use, and already have a (overpowered) motor. So, any thoughts regarding frames/workrests?
 
Lorien said:
I'm getting really warm to the idea of having a disc grinder to use, and already have a (overpowered) motor. So, any thoughts regarding frames/workrests?
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Sounds like you already have a spare motor available but I thought I'd update the thread regarding my original question. I ended up with a 9" flat disc that I have been using on my grinder per my original question. It has been working great for what I expected. Not as nice as a dedicated machine but I had vfd capability from day one and just plan my work flow to avoid going back and forth between needing the disc vs. the belt set up. I made a low tech work rest for the disc which works for squaring up pieces but mainly I've been using the disc free hand with my grinder turned horizontal.
 
what I'd like to do is hook this motor up to the vfd for my grinder, which is 2hp 3500rpm. The motor I have, (aka; don't need to buy) is 1.5hp 1750rpm. Not sure if it's possible, but I thought I saw something about a toggle for something like this somewhere?
Total neophyte when it comes to all this stuff but I'm starting to understand a tiny amount. Probably just enough to get myself into some real trouble
 
Toggles and switches are fine but can be limiting. I prefer to have a three phase female plug on the end of the cord coming out of the vfd. All three phase motors that you want to run in your shop (that are the same or less hp than the vfd is rated) have a male three phase plug at the end of the cord coming from the motor. Plug in whatever motor you need when you need to use it. In addition to the first grinder that I had wired this way, I have run a second grinder, surface grinder, bridgeport mill and a very large horizontal bandsaw all from the same vfd. Only one at a time though.
 
JMJones said:
Toggles and switches are fine but can be limiting. I prefer to have a three phase female plug on the end of the cord coming out of the vfd. All three phase motors that you want to run in your shop (that are the same or less hp than the vfd is rated) have a male three phase plug at the end of the cord coming from the motor. Plug in whatever motor you need when you need to use it. In addition to the first grinder that I had wired this way, I have run a second grinder, surface grinder, bridgeport mill and a very large horizontal bandsaw all from the same vfd. Only one at a time though.
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wow that sounds super easy!
 
Lorien said:
wow that sounds super easy!
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What you want is a rotary cam switch.

Post in thread 'Running two grinders off one VFD' https://www.bladeforums.com/threads/running-two-grinders-off-one-vfd.1777906/post-20364540

I use one between my two grinders as well.
svuvcxL.jpeg
 
thank you, I knew there was a thread about this. Aptly named, too. Shoulda been easy enough for me to search out given the descriptive title :rolleyes:
well, I won't beat myself up about that- thanks again!
 
JMJones said:
Toggles and switches are fine but can be limiting. I prefer to have a three phase female plug on the end of the cord coming out of the vfd. All three phase motors that you want to run in your shop (that are the same or less hp than the vfd is rated) have a male three phase plug at the end of the cord coming from the motor. Plug in whatever motor you need when you need to use it. In addition to the first grinder that I had wired this way, I have run a second grinder, surface grinder, bridgeport mill and a very large horizontal bandsaw all from the same vfd. Only one at a time though.
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Do the various machines in question have to have the same horsepower? Don't VFDs have a jumper for the HP of the machine they're driving?

-Mark
 
NeutronStar said:
Do the various machines in question have to have the same horsepower? Don't VFDs have a jumper for the HP of the machine they're driving?

-Mark
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I am by no means an authority on the electronic thingamajigs, but as long as the VFD packs the same or more HP than the machine it's fine in my experience.
 
Scaniaman said:
I am by no means an authority on the electronic thingamajigs, but as long as the VFD packs the same or more HP than the machine it's fine in my experience.
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The thing to be careful about is if your vfd is configured to output more current than your motor is rated for then you risk burning it up if you push it too hard. For example a vfd set for 2 hp but hooked up to a 1 hp motor will run fine until you push the motor hard enough to draw more than its data plate current at which point you're risking overheating it and burning it up. If the vfd was set to 1 hp it would limit the output current to keep the motor safe.
 
Do any of the modern VFDs have programable HP settings? I mean by keyboard setting, not changing the jumper or module.
 
Stacy E. Apelt - Bladesmith said:
Do any of the modern VFDs have programable HP settings? I mean by keyboard setting, not changing the jumper or module.
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I'm currently running a KBDA-29 and the output current limit is set via the front keypad but it's a bit of a cumbersome process, not something you'd want to be changing every day.
 
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