Worth Upgrading To Inveter Rated Motor 1340gt?

marcusp323

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Been going back & forth on whether to buy one for a while. The stock 3 phase hasn't given any trouble or anything, but just want to hear from people who have done it & whether they think the $$ were well spent.
Mark
 
I replaced the stock 3-phase motor with a Baldor as part of a VFD conversions. I actually never used the stock motor, so I can't compare the two, but I will say the Baldor is dead quiet and vibration free and has amazing torque at the low end. The Baldor I bought (on eBay NOS) fits in the space of the old motor, and the only mods required were to shorten the shaft on the unused end, and drill two new mounting holes in the stock PM1340 mounting bracket.

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Curious where you bought your replacement pulley too. I can't seem to find any that really run very true!
 
I have had good luck with Surplus Center on pulleys. I must say that I use their printed catalog versus their website. The catalog is easier to deal with.
 
Tried a couple from McMaster-Carr & was sorely disappointed. Used to getting quality stuff from them but not so much in that area evidently!
 
Curious where you bought your replacement pulley too. I can't seem to find any that really run very true!

When I did the conversion on my PM-1440GT the only manufacturer that had the size pulley I needed was Gates. I found the best price to be from Motion Industries. It has a small bit of run-out due to the slip fit on the motor shaft but once the belts are properly tensioned (using a belt tension gauge) it has no adverse affect and runs very smooth.
 
The stock motor works well, I would say the major limitation is that I would not push the motor beyond 90Hz since the Hp will probably fall off, and low/high speed cooling could be an issue with continuous use. An inverter rated motor (Marathon BlackMax, BlueMax, Baldor IDNM, etc.) are usually rated to 120Hz with no Hp drop off, and usually are good to much higher RPM with full Hp (5000-5500). By going to 120 Hz, you can run the lathe off of a single pulley from ~50 RPM to a top end of between 1800-2000 RPM depending on the motor pulley. Something like a 2.7" (2.5-2.9") on the motor and the larger drive pulley works well, you need the next size longer belt (like a BX25). Most of these type of motors are TENV, so built with a lot of iron/metal to dissipate the heat and are rated at all RPMs with no additional cooling needed. Mine gets almost to hot to touch with continuous use, but these are rated to withstand temperatures to around 300F. They are pretty bullet proof and very quiet without the fan. An inverter/vector motor can be pushed to higher overloads for short periods (180-200% for a minute), so with the a better VFD they can be pushed harder and can handle a very wide speed range. The motor offers a bit tighter control over the RPM under load (a few RPM difference) and maybe better controlled braking, but we are talking small differences.

I do not think it pays to run out and buy a new motor, but they do come up routinely on ePay for as low as $100 plus shipping for new 2Hp Marathon inverter rated motors (reasonable price range is 100-300). If you get a great deal and have a few extra $, than it may be worthwhile.
http://www.ebay.com/itm/Marathon-Black-Max-Motor-2-HP-60HZ-230-260V-5-400RPM-1-7-AMPS-/381869088167
 
If you do get an inverter rated motor, don't get Leeson's.

I was very disappointed to pay extra money to get Leeson's wattsaver inverter duty motor with a "made in China" label on it.
 
Sounds like my pulley foray, a disappointing tag to find, attached to far too many labels one used to consider high quality stuff. Not that the Chinese aren't capable of making good products, just that it's a lot of hit or miss in my experience. :(
 
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