Open motors vs TEFC

[Rick Fisher]

I sold my 6" Delta X jointer the other day. I took the rear cover off to tighten the belt for the new owner and noticed that the motor is an open style.

I have owned it for almost 5 years and never had a problem, and... it was covered in dust.. worked fine..

So I have to wonder.. if Delta put this type of motor on a jointer.. what is all the fuss with TEFC.

Has anyone ever had a problem with an open drip motor on a woodworking tool?

[Mike Henderson]

Yep, I had a open frame motor (Baldor) on my table saw and the sawdust used to foul the centrifugal switch on a regular basis. I finally replaced it with a TEFC and have never had a problem since.

All I had to do with the old motor was blow it out with compressed air and it would start working again, but it's a pain when you're ready to do some work and the saw won't start.

Mike

[george wilson]

Never put an open motor on a bandsaw for cutting metal. Some people I know did it,and the motor blew out in a few months.

[Tom Veatch]

I'm with Mike and George. In a dirty environment and a capacitor start motor, TEFC is the only way to go with a capacitor start motor. The only advantage to an ODP enclosure, that I can see, is you know for sure when you let the magic smoke out.

[Mike Henderson]

So you might ask, "If TEFC is so good, why aren't all motors TEFC?"

The answer is that an open frame motor cools better. The TEFC has to be built "better" to get the heat out since the fan only blows air over the housing and not through the inside. So the TEFC is more expensive. When the environment is not dirty, an open frame motor is the better choice.

Mike

[Rick Fisher]

I have this big jointer coming...

Its 3 Phase.

Sadly, a VFD is going to cost almost $1000.00.. and I have to disable the electromag brake on the motor...

If I get a rotary phase converter, I figure I should get a big one, for future expansion. . $2000.00..

New single phase motor.. $500.00

Problem with a single phase motor swap-out is that the machine needs a C-face mount.. and the Italian motor is spaced differently than the Domestic motors.. sigh. .. So I would need a flange and a new sheave..
In addition, the motor needs to be smaller HP, or I need a different Mag starter..

Good times.

I wouldnt put an open drip motor on it.. but when I saw that one on the Delta, I figured ..

[Tom Veatch]

When the environment is not dirty, an open frame motor is the better choice.

Perhaps I should have stated it explicity, but I thought the context was "dirty environment".

[Rod Sheridan]

I had the same experience as Mike, my previous saw (Craftsman) had an open frame motor that occasionally needed the sawdust blown out of it to free up the starting switch.

A TEFC motor will keep the inside of the motor clean, however you have to keep the outside clean. If the motor gets caked in gunk, the fan blows cooling air over the gunk, which is a thermal insulator. The motor is now running much hotter than designed for.

Now admittedly, in the light use home shop environment it might not become an issue, however in a production shop it's good practice to clean off the motor during normal inspections.

Regards, Rod.

[Larry Edgerton]

I have this big jointer coming...

Its 3 Phase.

Sadly, a VFD is going to cost almost $1000.00.. and I have to disable the electromag brake on the motor...

If I get a rotary phase converter, I figure I should get a big one, for future expansion. . $2000.00..

New single phase motor.. $500.00

Problem with a single phase motor swap-out is that the machine needs a C-face mount.. and the Italian motor is spaced differently than the Domestic motors.. sigh. .. So I would need a flange and a new sheave..
In addition, the motor needs to be smaller HP, or I need a different Mag starter..

Good times.

I wouldnt put an open drip motor on it.. but when I saw that one on the Delta, I figured ..

Rick

I have a 50 hp Rotophase converter and I was thinking of looking at into option of running my whole shop off of a large VFD. Not sure if this can be done on multiple machines. None of the electricians I deal with know if that can be done. If you find some good reading on large VFD's let me know please.

Its not good to let a roto converter run with no load, and I an tired of switching it on and off. I'm setting up a new shop soon and would like to avoid that. One thing I have thought about is having someone make me up a remote for the converter that will take the 100Amp startup.

Congrats on the new jointer. That will be my next major investment, then a 42" widebelt..... and a tractor.......and a woodmizer.......and a spray booth.....................

[Rick Fisher]

Larry, there is a Rotarty Phase converter made in Arizona, sold by Laguna, which seems to have a wireless remote?

I know very little about it but saw the remote in a picture that Benny sent me.

Unless he left his keys on the machine when he sent me the pic. lol..

I think the remote is just operating a relay? pretty small unit.

Relay may not be right.

I am planning on attaching the starter for the RPC, right to the jointer..

You can run mulitple motors on a VFD, but I would wait. The larger ones tend to create larger issues .. Its the fastest growing technology and I think in a few years, they will be far superior to what they are today.

If you call Laguna, they can probably get you a wireless remote.. I could be wrong..

[Howard Acheson]

An open drip motor on a jointer is perfectly fine. A jointer and planer puts out large chips and little "dust". Therefor, there is not the fine dust that can clog up a motor. You will typically find TEFC motors on tablesaws where the motor in inside the sawbox. Therefore it's in a very dusty environment. Some contractor saws have open drip motors, some have TEFC but the motor is outside of the primary dust generating environment.

[Steve Rozmiarek]

This is an extreme example of one of the reasons that I've always considered TEFC to be worth the extra $.

Late last night, I was working on a large pump motor, 100 hp, 480 volt 3 phase. It had blown two 150 amp fuses. Usually that means a dead motor, but it did not test positive for faults to ground, so I refused and hit the start. I was ready, but when that much current gets turned loose to make windings into little copper BB's, it's impressive. Especially at night! That motor was not a TEFC, motor, and it shot hot stuff all over the place. Burned some weeds around the well too, but if a open motor lets go in a sawdust filled woodshop, it may not just trim the weeds...

I don't think anything would have contained the power unleased in that well motor, but a 3 hp jointer motor may be contained by a TEFC case if it fails catostropically? Thats my theory any how, thoughts?

[Mike Henderson]

I've seen small motors burn up, meaning the stator coil gets extremely hot, but I've never seen a small motor "blow up", meaning spit melted copper.

You should have a small motor on a protected circuit so the breakers should kick in before you get real fireworks. You'd essentially have to have a short to ground to get it to spit melted copper.

Mike

[Larry Edgerton]

Steve, I have another bit in my pocket, I'll try it again......

[Steve Rozmiarek]

Steve, I have another bit in my pocket, I'll try it again......


LOL! Sounds good Larry!

[Scott T Smith]

I have this big jointer coming...

Its 3 Phase.

Sadly, a VFD is going to cost almost $1000.00.. and I have to disable the electromag brake on the motor...

If I get a rotary phase converter, I figure I should get a big one, for future expansion. . $2000.00..

New single phase motor.. $500.00

..


The problem with most VFD's is that they are not rated to take the startup surge from a motor at full power, and you have to start them at 0 hertz and then spin the VFD up to 60 hertz (or 50, depending upon where you're located).

For this reason, I would not want to run an entire shop on a VFD.

In two of my shops, I have/had a 30hp phase converter feeding a 3 phase load center, and all of the machines hooked into that. Quick, easy, and you can stack converters if you need more power.

Probably your least expensive option is the motor replacement, but a whole-shop rotary phase converter may be the least expensive in the long run. You can often pick them up used for a pretty good deal (I recall that I have around $700.00 in mine).

In fact, I have a spare 240 single phase to 208 three phase converter if you're interested. I forget the HP, but it's in the 25 - 30 hp range (or thereabouts).