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Found a DC motor, should I buy it?
- Thread starter galadduin
- Start date
Nathan the Machinist
KnifeMaker / Machinist / Evil Genius
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Personally, I'd stick with three phase AC and a VFD over DC with and a DC drive.
The AC is locked (more or less) to the frequency supplied. The DC is controlled via voltage, and there is more slippage unless there is RPM feedback to the amp.
And that one is made in China.
..my .02
The AC is locked (more or less) to the frequency supplied. The DC is controlled via voltage, and there is more slippage unless there is RPM feedback to the amp.
And that one is made in China.
..my .02
- Joined
- Feb 17, 2007
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- 3,375
A 3 hp 3ph should be saved for a belt grinder with VFD. I think it would be overkill with a disk. It should reverse by switching any 2 inputs. You would still need some form of phase converter to make the 3 ph work with normal 220.
The DC motor should work for a disk, if it is totally enclosed. If not it won't last long. You would also need a big enough variable DC power supply to use it
For my disk grinder I use a 1hp 3ph TECF from Grizzly
http://www.grizzly.com/outlet/Motor-1-HP-3-Phase-3600-RPM-TEFC-230V-460V/G6239 $85
and a TECO VFD http://dealerselectric.com/item.asp?cID=&PID=417 $131
It makes varible 220 3ph and uses 110v input nad says protected chassis. I don't know how well protected. I mount mine high on the wall where I can read it and control the speed and direction with a pot and spdt switch mounted by the grinder.
I also set the grinder up like this so I can change out heads and use it as a buffer. The addition of a foot switch is also very handy. Get your work where you want it and step on the petal to start turning.
You mount the shaft on bearings mounted on a piece that has a sg tube at 90 degrees, that slides into a receiver like a KMG grinders use. The motor is mounted below. By sliding the tube back in the receiver it loosens the belt and you can remove the shaft assy. When installing shaft assy you put belts on pulleys and then pull belt tight and lock down tube in receiver with knob
The DC motor should work for a disk, if it is totally enclosed. If not it won't last long. You would also need a big enough variable DC power supply to use it
For my disk grinder I use a 1hp 3ph TECF from Grizzly
http://www.grizzly.com/outlet/Motor-1-HP-3-Phase-3600-RPM-TEFC-230V-460V/G6239 $85
and a TECO VFD http://dealerselectric.com/item.asp?cID=&PID=417 $131
It makes varible 220 3ph and uses 110v input nad says protected chassis. I don't know how well protected. I mount mine high on the wall where I can read it and control the speed and direction with a pot and spdt switch mounted by the grinder.
I also set the grinder up like this so I can change out heads and use it as a buffer. The addition of a foot switch is also very handy. Get your work where you want it and step on the petal to start turning.
You mount the shaft on bearings mounted on a piece that has a sg tube at 90 degrees, that slides into a receiver like a KMG grinders use. The motor is mounted below. By sliding the tube back in the receiver it loosens the belt and you can remove the shaft assy. When installing shaft assy you put belts on pulleys and then pull belt tight and lock down tube in receiver with knob
Nathan the Machinist
KnifeMaker / Machinist / Evil Genius
Moderator
Knifemaker / Craftsman / Service Provider
- Joined
- Feb 13, 2007
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- 19,121
Yes, all three phase motors I've ever come across can be reversed simply by swapping any two lines.
A four step pulley on the input and on the output sides give a good speed range on my knife grinder. 1000-5000 SFM in useful increments with my particular setup. That is two step pulleys - one on the motor, on one the machine - gives you four speeds across a nice range.
Because the resulting belt lengths work out the same I was able to rigidly attach the motor to the bench and just roll the belt over to change speeds. It was simple to setup and it literally just takes a couple seconds to change speeds. This is my setup:
It was very simple to setup. Works for me.
A four step pulley on the input and on the output sides give a good speed range on my knife grinder. 1000-5000 SFM in useful increments with my particular setup. That is two step pulleys - one on the motor, on one the machine - gives you four speeds across a nice range.
Because the resulting belt lengths work out the same I was able to rigidly attach the motor to the bench and just roll the belt over to change speeds. It was simple to setup and it literally just takes a couple seconds to change speeds. This is my setup:
It was very simple to setup. Works for me.
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- Dec 25, 2004
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- 1,363
A neat setup you have there. I think I'll implement a similar design. I have three phaze electricity in my shop so I dont have to change a thing for my AC motors
. Thanks Jim for detailed pics. This really cleared my mind up :thumbup::thumbup:...Nathan, I have a similar setup for my 3 hp belt grinder also:
It works great for me.. I use the buffer attachment without belt loaded at highest speed (which is not much). I run the belt at minimum and medium speed pulleys. I think I need to tweak the alignment of wheels as it wobbles at high speed...
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- Nov 23, 2003
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- 773
That looks like it may be a treadmill motor. They are not rated for the duty cycles that are typical of grinding applications, and are typically rated at higher hp than they actually put out.
I wouldn't use that motor simply because it is a 4600 rpm motor. Much too fast for a disk grinder.
Mike L.
I wouldn't use that motor simply because it is a 4600 rpm motor. Much too fast for a disk grinder.
Mike L.
- Joined
- Nov 23, 2008
- Messages
- 437
Galladuin
If you've got the dc controller I've got a DC treadmill motor that you can have if you pay shipping.
Tore apart my controller and built an electro-etcher out of the parts, LOL.
3 Phase is the way to go though, IMHO.
I just wired a dryer outlet on my Teco last weekend. Wired a dryer cord on both KMG and Disk motor. Eventually I'm hoping to also add a horizontal to the mix. All variable speed reversable on one controller. :thumbup::thumbup::thumbup:
Josh
If you've got the dc controller I've got a DC treadmill motor that you can have if you pay shipping.
Tore apart my controller and built an electro-etcher out of the parts, LOL.
3 Phase is the way to go though, IMHO.
I just wired a dryer outlet on my Teco last weekend. Wired a dryer cord on both KMG and Disk motor. Eventually I'm hoping to also add a horizontal to the mix. All variable speed reversable on one controller. :thumbup::thumbup::thumbup:
Josh