Help!! Stalling out my Grinder...

Normark

Normark

Joined
Nov 7, 1999
Messages
6,651
Hey Guys....

I'm Stalling out a Brand new Variable speed 2X72 with a 1hp AC motor and Frequency Drive, running Wide open...

Any suggestions ?
Am I pushing too hard, is something wrong ?

Really frustrated...

Help!!

ttyle

Eric...
 
You flat grinding ?. That will definately put the motor to the test. I have a 1 1/2 hp and frequency drive setup and havent bogged it down yet, but i havent really pushed all that hard either. Did you play around with any of the settings on the drive Eric?
 
1HP is a lot for a drill,but not much for a 2X72 grinder.A 1.5 to 2HP will do much better.It is possible that the drive is creating low torque,especially at low speed.
Again,more power to start means more power after loss.
Stacy
 
I have a 1.5 hp variable speed and have often killed it when tapering tangs. There's a lot of friction when flat grinding and it's no surprise you might be bogging down a 1 hp motor. I'd say either be patient and grind slower or upgrade to 2 hp - actually I recommend both. ;) Had I known then what I do now, I'd have definately sprung for the 2 hp option on my BIII. We sure do live and learn, eh? Hang in there, sounds to me like you're experiencing the normal stuff.
 
Did you get the Bee variable Eric? It's a nice grinder but not a powerhouse. It's pretty easy to bog down even sanding wood blocks flat if you lean into it. It reminds me that grinding is about finesse - not power - and sometimes I need that reminder when I'm getting impatient.

The Bee needs some mods from it's starting point. The platen is soft and benefits greatly from a ceramic liner. Also, the 2 1/2 " platen doesn't make much sense on a 2" grinder. I made one out of 5160 that is about 2" wide. That didn't wear as fast as the original but the ceramic liner is the cat's meow!

The tool rest needs some mods so it is more adjustable. I haven't got around to this part yet but you will eventually see the need.

The placement of the controls seems a little dangerous, way at the back. Extra care when leaning for them is called for. I would suggest a kill switch on the floor at your feet is an important safety feature.
Lastly, one of the reasons I bought it was because I liked the idea of the closed housing for dust collection. I have a 1 1/2 horse dust collector - and it keeps the airborn stuff down but the housing still packs up with debris pretty quick. When switching from wood to metal, you have to clean it pretty good or put up with those annoying little fires. ;)

Hope this helps a bit.
 
Your VFD has several programmable features that can help. You should consult the moanual...or a tech at the manufacturer.

You might have current limit on the drive set too low...that is that the drive will only supply 1/2 hp rather than your full 1 hp. Can you verify the current to the motor ( clamp-on amp meter...or current display on the drive)?

Also, for a belt grinder you can reduce the slip compensation...or speed correction feature which makes the controller increase the power to maintain a constant speed. What happens is that the controller may sense a samll 1% loss in speed...then crank in 200% power to regain the negligible speed loss...resulting in a shutdown fault. Disabling or reducing slip comp will keep the controller and motor much cooler in the long run while supplying max power for the peak loads while neglecting the trival loads. This is the best set-up for a belt grinder.

The VFD may also have setting for hertz-volts curves.....which I can't explain but I know makes big changes in performance...you'll need to talk to the techs.


Aside from all the garbbly-gook I just posted....the bad news....1hp is on the small size...I think with most certainty....that it is just too small. When finacially feasible, use the 1hp for a disk...and jump up to a 2hp for the belt grinder. The more comfortable you get with the grinder....the more you gonna want more power.


Good luck,
Rob
 
I asked on your first thread about this grinder, and you didn't reply, so I'll ask again here.

What kind of grinder, and motor setup are you using??????????????:confused:
 
Eric, keep in mind if you go to 1.5 (sometimes, depends on the motor), or 2HP always, you will need to run the motor off a 220V outlet/circuit, not 110. I got a sweet 2HP motor for $100, then learned that I needed to have a 200V outlet, then learned my panel in the basement was full, etc. Paying an electrician $175 or so for the work wasn't in my budget, so I had to stick with a 1HP, unfortunately. Haven't stalled it yet, though. Anyway, depending on your home/shop setup electric-wise, you may need to figure in some extra wiring and electrical crap if you upgrade.
 
Chiro75 said:
Eric, keep in mind if you go to 1.5 (sometimes, depends on the motor), or 2HP always, you will need to run the motor off a 220V outlet/circuit, not 110.
Click to expand...
Lots of motors are made to run off 110 or 220 volts. I have a 3hp 1750 rpm Baldor that I runs off 110 volts on a 30 amp circuit. It works great because it is set up correctly. It cannot be stalled. ;)

Chiro75 said:
I got a sweet 2HP motor for $100, then learned that I needed to have a 200V outlet, then learned my panel in the basement was full, etc. Paying an electrician $175 or so for the work wasn't in my budget, so I had to stick with a 1HP, unfortunately.
Click to expand...
If you don't know what you are doing, hire an electrician. It is safer and cheaper in the long run. Not hiring an electrician is like me doing my own back adjustments. :rolleyes:
 
Lots of motors are made to run off 110 or 220 volts. I have a 3hp 1750 rpm Baldor that I runs off 110 volts on a 30 amp circuit. It works great because it is set up correctly. It cannot be stalled.
Click to expand...
Wouldn't it use less power if it ran off 220V? Or less amperage, I guess is the way to look at it? I wasn't aware that you could run something like that off 110. The 2HP motor I had would've run at 20-24 amps, so I suppose if I had a 30 amp breaker that the outlet was wired to I could've done the same. Interesting!

If you don't know what you are doing, hire an electrician. It is safer and cheaper in the long run. Not hiring an electrician is like me doing my own back adjustments.
Click to expand...
Absolutely! Which is why I downgraded to a 1HP that runs fine off the existing electrical in my basement. It wasn't in my budget to pay someone at the time for the electrical work, so I chose to downgrade my motor. I didn't even like the idea of wiring up the motor myself, but an electrician walked me through it, so I was confident that it was done right.
 
Rob said what I would have said. There would seem to be a limiting factor in the current.

I've had DC and AC motors on variable speed - both 1.5 HP.

I could easily bog the DC motor/drive - but it really takes some hard pushing to bog the AC motor/drive.

Like Mike said, has a lot to do with what motor and drive you have.

What I've got now runs off 220V but is only 1.5 HP. It draws very little current (keeps my elec. panel happy). I can't remember the last time I bogged it down. I do alot of cutting on the bandsaw first - so less hogging at the grinder. Also, I avoid pushing hard against the platen because removing deep scratches is the KNIFEMAKER'S BANE and not worth any time I might save. Going slower cuts down on the oopsies too. Tests your patience at first, but if you give it a few minutes, you quickly adjust. I have to do this EVERY time I hit the grinder....like calisthetics...
 
Hey Guys....

Holy cow,, Thanks for all of the replies..I really appreciate it..

Mike,, it is a Bee 2x72 with a 1HP AC motor with Freq drive...

Well the nice thing about it I guess is that it's a AC motor,, and compared to the price of a 2HP DC motor with runs about $900.00,, to throw a 2HP AC motor shouldn't be a problem..

Power isn't a problem in my shop right now..Have Tons of room left in the panel,,and the only thing I don't like to do,,is wire motors in..Everything else is easy..

I haven't played with any of the pots on the inside of the controller, although I have had to open to have a peak...

As far as this grinder goes, yaa already by looking at it,, there are a few things that I don't like about it,,other than that it seems to be a decent machine.. I've been in contact with Darren Ellis about ceramic liners,,and will probably order a couple once I figure this out a little more...

I think maybe what I'm doing is just being a little too gung ho with it,,and need to relax...

I'm the kind of guy who likes to take things to the max right away to see what it can do.. One of the very reasons I don't drive a motorcycle(130MPH) Way too scary to do again..:)

Anyway,, I'm going to call on Monday and see if there are any adjustments to be made
if not,, I'll just buy a 2HP and be done with it..

Thanks Guys,, you've all been a big help

ttyle

Eric...
 
120, or 220, you're using the same amount of power. On 220, you're just using half the amperage(per leg) as it's split on each line, rather that all of it being on one line, as in 120v.
I have a 31/2HP compressor that runs on 120V:eek:, but they lie like dogs. I doubt it it would actually measure 1 1/2 in reality. Friggin compressor people invented lying, I think.
If it was really as rated, I would have to run at least #10, or even 8 wire on that circuit, and, of course, upgrade the breaker, which is probably what Chuck has done.
Not doing that will have the insurance company examining the ruins of your house trying to find the cause of the fire.:eek:;)

Try putting a pyrocerm liner on your platen. That will cut friction by more than half(I'm assuming you're having problems bogging when using the platen).

Another thing is, get good belts like 3M etc., and don't push so hard. Let the abrasive do the work.

I use a couple of Burr King grinders, and they come stock with a 1HP AC motors.
I switched over to variable speed 1 1/2HP, but don't remember any problems using that AC motor when grinding.

I used it for years after as a disk grinder, and another knifemaker is now using that same 1HP on a Coote grinder with no problems.

Make sure everything is set up properly, and if there's a belt drive on that grinder(but I think it's like an overgrown Wilson grinder though), make sure it's not slipping. But, IIRC that drives off an idler wheel. Also, try some tape on that drive wheel if it's not rubber covered. Might give it some additional traction.
Just a thought.:D
 
When you get your hands on a 2HP variable speed DC motor,you will never look back on your AC days again.
 
Hey Guys...

Hollow ground a 1/4" blank tonight on a 10" wheel, and it did much better....
It's gotta be the flat grinding that Bogs it down...

I even hogged with it,, and it held up pretty good....

Still want to crank up the volume on it if possible....

Thanks

Eric...
 
Normark said:
Hey Guys...

Hollow ground a 1/4" blank tonight on a 10" wheel, and it did much better....
It's gotta be the flat grinding that Bogs it down...

Eric...
Click to expand...
As I said a couple of posts above, try a pyroceram liner on your platen and it'll even ease the bogging doing flat grinding.

But profiling and such are much better done on a wheel.
 
Hey Mike...

Yaaa I've already talked with Darren Ellis about them..

Just have to figure out what size I need...

How thick are those ceramic liners,, and will they chip or crack easily ??

Reason I ask is the I want to overhang the ceramic on the platen,,just a little,,so I can track the belt over to one side to blend the plunge lines...

Will the ceramic hold up to that overhang ??

ttyle

Eric...
 
They're about 3/16-1/4" thick, some might go as high as 3/8".

There's really no reason to have the pyroceram any wider than the steel platen for the reasons you mention, as the belt can be tracked off the edge if it's the same width as the platen, and you get better support.

Make sure to round over the top, and bottom corners of that liner so the belt has it easier getting on, and off the platen. You don't have to get crazy with this, just a nice simple radius is all that's needed. Just saves wear, and tear on the belts.
You can do that with a 220 belt followed by a 400 or so. You just don't want to leave deep scratches or they'll chip out.

When you round over the ends, it will glow an orange color. That's normal so don't worry about it, but make sure you wear eye, and lung protection when you do this.

Leave the side edges alone. They don't need to be rounded over, and it's hard to get the same radius on both sides if you try.

Incidentally, you want the pyroceram platen to push the belt out a little when it's installed. It works best to give you the flattest grinds that way, and is the biggest reason for rounding the top, and bottom.


Edited to add; They're pretty tough, but if dropped they can easily crack.
Make sure the platen is flat when you install so it get's good support all along it's length. You don't want to put one on a bowed platen as it will increase chances of it cracking. Mine's been on for some years now.

It will let you machine run a lot easier as it will decrease drag, and it will dissapate heat from grinding too, which will make everything last longer.
 
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