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Electric Motor and Pulley Size

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Forum topic by Charlie75 posted 03-30-2014 08:09 PM 720 views 0 times favorited 10 replies Add to Favorites Watch
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Charlie75

239 posts in 1017 days


03-30-2014 08:09 PM

Nice day here in Michigan for a change. Supposed to get warmer in the next week or two so maybe i can make some progress on my band saw restore.

Today I was looking at the motor and noticed it is pretty much packed full of saw dust. I am surprised it runs but it does. So my question is what am I getting into if I take this thing apart and clean it out? I have torn a lot of things apart but never a motor.

Also, would it be a good idea to replace the bearings while it’s apart? It seems to run quiet and there is no end play. One thing I do want to do is replace the cord. The saw originally was turned on and off by a switch on the end of the motor. I want to get one of those safety switches and mount it on the saw.

One more question not related to the motor except remotely. That’s the pulley size. The motor pulley that’s on there now measures 2 1/4” on the outside and the pulley that is presently for the saw measures 7 3/4”. Are pulleys typiclely measured at the widest part or the bottom of the groove?

Charlie

-- Charlie75, Alto


10 replies so far

View MrUnix's profile

MrUnix

661 posts in 951 days


#1 posted 03-30-2014 09:51 PM

The OEM setup for that saw was a 2.75” motor pulley and an 8” wheel pulley.. that gives you a SFPM (surface feet per minute) of 2172. With a 2.25” motor pulley and a 7.75” wheel pulley, the SFPM is 1835, so it is close to OEM. Measurements are outside diameter.

As for the motor.. you might be able to clean it out with just some compressed air, but if it’s really packed in, you will need to split it open. Not too difficult.. there should only be 4 bolts holding the end bells on. Most motors are very similar, but each manufacturer has it’s own quirks. If you do split it open, it might be a good idea to go ahead and replace the bearings if it has them; not all do and many just have bronze sleeves that need to be oiled every now and then via a fill cap directly above. Make sure you mark the relationship between the end bells and main housing so you can put them back on properly oriented.

Having said that.. given what you have already gone through, I’d probably skip tearing into the motor :) If it works, let it be. You can always come back and tear it apart later after you have to, and in the mean time, you can be making some sawdust with that machine.

Also, if you have an original motor.. they had the switch on the motor proper and a rod that ran up to beside the machine to control the on/off function. If you check some of the machines over at OWWM or VintageMachinery.org, you will see plenty of examples. If it is indeed original, I’d keep it that way and look into finding or making the switch rod.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View Charlie75's profile

Charlie75

239 posts in 1017 days


#2 posted 03-30-2014 11:00 PM

Thanks Brad. I think I may just replace the pulleys. At least the motor one. Fact I may even have one that size. If I can find it. lol Not sure about the other pulley.

I am not sure the motor is full of saw dust but there sure seems to be a lot. I have not used the compressor on it yet but I did hold a vacume against it. I’ll try the compressor next. At this point I guess I will leave it alone. It is not the original motor I don’t think. If memories serve me I think the PO told me he had replaced it when he first got the saw. The afore mentioned switch is just a push button switch mounted in the removable plate at the end of the motor. I still do plan on replacing the cord and will probably eliminate that switch. The present cord is rather tattered.

For now, I guess that motor falls under the catagory of if it ain’t broke leave it alone. Oh, I think there probably are bearings in this motor as there are no means for lubrication. My table saw on the other hand does have those so I know what your talking about.

Charlie

-- Charlie75, Alto

View Newbiewoodworker43's profile

Newbiewoodworker43

130 posts in 1195 days


#3 posted 03-30-2014 11:52 PM

I have thought about cracking open the motor from my BS and not the jointer but have hesitated based on the fact that they are working fine and I have never done this before. I probably should for both of these motors especially the BS as it was being used to cut plastic and that stuff was all over the BS when I was cleaning it up. I am sure there must be a ton inside.

On an associated topic, how do you plan on mounting the motor? Mine is currently just bolted down to the stand. It is a homemade stand. I was planning on building a new one and found a blog about a guy who did this and mounted the motor on a hunk of wood attached to the stand with a hinge. The hinge let the weight of the motor maintain the pressure on the belt, like the way my Cman contractor’s saw works. I am also trying to find a Delta flare legged stand for the BS but I have not had any luck as yet

The original motor that came with my 37-207 6” jointer does not have a mount. So I am not sure how I am going to put that on. I also have to make it so that the belt guard fits. I thought about making a mount but will probably try and find one somewhere.

-- ---Howard, Amesbury MA

View Shawn Masterson's profile

Shawn Masterson

1262 posts in 701 days


#4 posted 03-31-2014 12:06 AM

MrUnix Spot on the exact advice I would have given. If you have never torn apart motor, they aren’t that hard, but the centrifugal switch can be tricky sometimes.

View Charlie75's profile

Charlie75

239 posts in 1017 days


#5 posted 03-31-2014 01:06 AM

Howard, All I would know about tearing into an electric motor would be to unplug it first. lol Actually, I am not afraid to give it a try it’s just that I am so anxious to make some saw dust with this that I really don’t want to get involved in one more project. If it does crap out in the future I will probably replace it at that point. Or repair it if I can.

If you recall I found a metal stand at Harbor Freight and put a 3/4” plywood top on it and also a 3/4” plywood shelf on the frame below. I cut a hole in the top and mounted the motor on the lower shelf. I fastened it right to the shelf and the link belt that I found at HF fit perfectly after removing one link.

Charlie

-- Charlie75, Alto

View Newbiewoodworker43's profile

Newbiewoodworker43

130 posts in 1195 days


#6 posted 03-31-2014 01:26 AM

Right Charlie, I remember now. Probably much faster and cheaper than constructing one out of wood. I am going to keep looking for a delta splayed leg stand because I like the way they look although I wonder how stable they really are.

For now, I am just going to keep the old stand in place. Once I get this jointer painted and reassembled I want to get going on the Adirondack chair I was building before I had to stop and get a Dust Collection system due to the mess the Cedar was making. Then the jointer came up and I am again not making saw dust but scraping rust! I think the resto of the BS is going to wait for some time.

-- ---Howard, Amesbury MA

View MrUnix's profile

MrUnix

661 posts in 951 days


#7 posted 03-31-2014 02:41 AM

I have a hinge type mount on my Delta.. pretty much just a regular hinge that is bolted to the stand on one side and the motor mount on the other side:

I also have found that if you just let the weight of the motor do the tensioning, you can run into some problems.. first off, the thing will just flop around and if you snap a belt, you could be looking at a lot more damage from the motor free falling uncontrolled. Another thing is that just the weight of the motor may not be enough to properly tension the belt. Also, they have a tendency to ‘hop’ on startups, which can, under the proper conditions, throw a belt.. and then you hit my first item above. You can see where I’m going here..

My solution was to add a tension adjustment to the opposite side, which consisted of a large machine screw, some washers, a nut and a spring;

Tension is adjusted by tightening or loosing the screw and it maintains the motor when a belt is not installed. To keep the nut from spinning under the rail, I dug through my box-o-junk out in the garage and found an old window bracket that fit perfect inside the mounting rail.. so I tack welded the nut to it which solved that problem:

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View Newbiewoodworker43's profile

Newbiewoodworker43

130 posts in 1195 days


#8 posted 03-31-2014 10:49 AM

I always wondered why my Cman table saw shudders upon start up and shut down. It has the gravity based motor mount / tensioning mechanism. Good to know that it is not something more serious going on.

I like the solution you came up with. It gives you the tensioning adjustment capability with stability. I will give this a try when I redo the stand for the BS.

For the Jointer I am thinking of just mounting it on a block of wood on the stand shelf and adjusting the link belt accordingly. I was lucky enough to get the belt guard with the first jointer and want to use it.

By the way, I noticed in your pics that you painted the pulley. Did you paint the inside (where the belt runs) or just the outside.

-- ---Howard, Amesbury MA

View tyvekboy's profile

tyvekboy

685 posts in 1766 days


#9 posted 03-31-2014 05:18 PM

As far as your switch for the band saw. Mine (circa 1970’s) had the same type of switch setup. I added a pull rod so I wouldn’t have to bend down to turn it on and off.

When I made my dust collection cover, I added a safety switch to my bandsaw.

it’s just mounted on a board that is attached to a hole in the upper frame.

This made it really easy to turn the saw on and off. You can get this type of safety switch at Rockler, Woodcraft, and even on Amazon. The end of the power cord just plugs in to a receptacle that comes off the safety switch.

Hope this helps.

-- Tyvekboy -- Marietta, GA

View Charlie75's profile

Charlie75

239 posts in 1017 days


#10 posted 03-31-2014 07:36 PM

My BS motor did not have a switch anything like yours. All it is is a little silver push button on the end of the motor. It may even have been added when the PO got the motor.

I want to add a switch just like the one you show in your final two images. Where did you get it?

Charlie

-- Charlie75, Alto

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