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Pully On A Treadmill Motor Shaft?

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Franko

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#1
I got this treadmill motor several years ago with dreams of putting it on my Grizzly G4000. For various reasons, I never got around to it. Now, I think it would make a great belt grinder motor. treadmill shaft_0424.JPG

It think it is a pretty good motor and I do have a controller that should work with it, but my problem is how do I attach a pully to the motor shaft which is step threaded but has no key groove. It might be possible to cut a key way in it, but it seems like it would not be a minor endeavor.

The shaft is 17mm and the major diameter of the threads is right at .5" with left hand threads.

Any suggestions? Am I missing something simple?
 

Chip_per

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#2
I think you may have to make a step collar that would fit and rest against the inner bearing race, and then the pulley would be sandwiched between it and the nut. "Friction drive".
 

GarageGuy

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#3
When you make your pulley, it also needs to have a step so the retainer nut clamps it against the shoulder.

It's just my opinion, but I wouldn't use an open construction external fan motor for a belt grinder. It will collect swarf. TEFC sealed motors are better for dirty environments like grinding. You could probably make an enclosure for it, though.

GG
 

rgray

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#4
On the ones I've had the cast pulley/flywheel was the fan for motor cooling. It had around a 6" dia. flywheel and the belt drive pulley around 1" dia all one piece with the threads for the shaft. If you had that it would probably be good to use it or maybe find one. Motor cooling would be nice and the air flow is out on the pto end. A hose or shroud could be added to the other end of the motor so it picks up clean air farther from the sanding.

I've been using a smaller treadmill motor (1 hp) for a sander for 2 years with no fan and it is still working fine. It is an 8" x 3" double wheel sander and mostly gets used for deburing. Not heavy use like a knife grinder.

I run it with a timing belt pulley whose inner dia is larger than the motor shaft. I made a spacer that I set screwed to the motor shaft and then the timing pulley is set screwed to that. Not very ridged but there isn't much pressure there and I haven't had any trouble with it.
 

caveBob

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#5
Couple things Franko, this was supposed to be just a quick & dirty setup for testing the pulley. Meant to cut then turn down the extra meat on the motor pulley, but never got back to that so far... and I have a better (much like yours) motor. But, surprisingly... has worked so well to this point, it remains, waiting for the better motor... still kinda hokey, but works very well tho...

hH1Fe3l.jpg

A very clever guy that goes by Dickeybird on another forum came up with an ingenious inexpensive solution which I bookmarked:

Cooling off a hot treadmill motor
http://bbs.homeshopmachinist.net/threads/47611-Cooling-off-a-hot-treadmill-motor

I will be doing that mod whenever I swap out the "better, newer" motor.

I have that same KB controller on my lathe... love it...
 

Franko

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#6
Russ, mine has a plastic ducted fan (one broken blade) on the other end that was pressed on small splines on the shaft.

I guess it wouldn't be impossible to mill or grind a flat on either shaft for a set screw. I'd have low expectations for a friction fit against the shoulder on the threaded shaft.
 

Mac1

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#7
I would just file or mill a flat on the shaft and use a setscrew.
 

Franko

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#8
Nice Cavebob. Is that large circular thing part of the pulley or a flange mount for the motor?

Dickybird is indeed very clever. Who knew you can heat shrink a plastic bottle on a form?
 
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Kernbigo

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#9
you can try this drive i have use lots of them (fenner drive key less locking device) google it
 

caveBob

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#10
Nice Cavebob. Is that large circular thing part of the pulley or a flange mount for the motor?

Dickybird is indeed very clever. Who knew you can heat shrink a plastic bottle on a form?
That's the original pulley that was mounted on the treadmill motor, like Russ mentioned... the smaller pulley that it connects to used to be mounted on the drive-shaft that propelled the treadmill. Kinda funny, got the whole treadmill free from Craigslist with a warning that it was broken and they just wanted it gone since it was replaced with a new treadmill. What was broken on it was the running belt had a rip on it, something got dropped on the belt, it developed a tear/hole, so they just bought a new one...

I pressed the smaller pulley off of the "drive-shaft", turned a hub out of aluminum to fit the inside diameter of the pulley, then locktighted it together. It's stuck on pretty good so far, no issues. :) 2 set screws on the aluminum inner hub.

Keyway would probably be best/ideal, but if you were to simply drill a starter hole say, 1/8" deep that's larger in diameter than the set screw, it would be easy peasy enough, and bet it would hold fine. You won't be starting/stopping a lot of mass just running a belt.

Forgot to mention, the local auto parts store had the serpentine belt (that correctly fits the pulleys) in stock.
 

rgray

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#11
I don't know why I had sander in mind. You clearly said G4000. The 17mm dimension made me think of an alternator pulley. Many are 17mm. They are not keyed or set screwed. An alternator on full charge is said to require up to 8 hp to turn. The pulley is just squeezed between a spacer so it clears the housing and a nut and washer on the end of the shaft. The nut is large dia but at 2.5 hp the 1/2 inch nut must be fine for the treadmill motor.

Can a spacer be put on your shaft and the pulley pinched between that and the end nut?

Nice sander/grinder cavebob...!!! Very nicely done.
 

Franko

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#12
Don't worry, you haven't lost it, Russ. I purchased the motor for the lathe, but never followed up. I am now considering it for my belt grinder.
 

Baithog

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#13
Someone may have already mentioned this, but I didn't see it. The pulley that is supposed to go on that motor shaft is threaded. My motor had a pulley with a smooth section of the bore that slip fitted over the smooth part of the shaft. That was followed by 1/2-13L threads. Turning the right direction, the pulley will lock itself to the shaft. Easiest way to mount a pulley on your motor would be to mimic the original pulley. Either bore and thread an existing pulley, or turn one from scratch. Left hand 1/2-13 taps are available. No keys, flats, or lock nuts needed.

Larry
 

Franko

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#14
Thanks Larry. That makes sense and is doable. Since It will be used on a belt grinder there won't be any reason to ever reverse it.
 

hman

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#15
I'm in the process of adapting a treadmill motor that looks like like caveBob's, to run a drill press.

Franko, you were asking about the "large circular thing" ... That's a single casting incorporating the (serpentine) V-belt pulley and a large flywheel. The motor side of the flywheel has several vanes (mine has 13) that act as a fan to draw air cooling through the motor. You'll notice a narrow plate behind the flywheel, which is about 1" narrower in diameter than the flywheel OD and helps the fan work.

I plan to simply bore out the existing multi-step drive pulley from the drill press, slip it over the serpentine pulley, and hold it with a set screw or two.

Since you don't have the flywheel/pulley for your motor, you will indeed have to make some kind of pulley yourself. One idea you might consider is to use a left-hand nut to secure the pulley, instead of having to thread it after boring. Just don't bore all the way through the pulley, so there'll be a shoulder to locate it against the shoulder of the motor shaft.

PS regarding the article caveBob cited ... that's a very interesting and useful idea! Thanks so much for posting.

It's one of those "flat forehead, high shoulders" things for me, as I once took a short course in blow molding. That's how soda bottles are made. The attached photo shows the injection molded pre-form used for 1 liter bottles. Theoretically, such a bottle could be shrunk back down to that size!
Liter bottle preform.jpg
 

Franko

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#16
I've seen them do that on How it's Made on TV.

My motor has a plastic cylinder with propellers inside it that is press fitted on the opposite end. I have another of those motors that is slightly smaller and runs on 90V DC. I got carried away buying motors on eBay at that time. The big motor came with the elevation gear motor which is a very cool little gizmo.
 

Franko

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#17

kd4gij

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#18
If you are going to use a setscrew insted of a flat on the shaft. Dimple the shaft. Put the pully on the shaft then with a drill for th thread size of the setscrew drill through the hole into the shaft the depth of the point of the drill. It is much stronger than a flat and won't work loose.
 

Bill C.

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#19

spongerich

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#20
Cutting a slot for a woodruff key shouldn't be that hard. You could probably do a good enough job with a Dremel tool and some stubs of worn down abrasive disks. (You save them don't you?)
 

lwhaples

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#21
This is what I found when searching Fenner Drives that looks like it would be applicable to my motor shaft.
They are a bit costy, at about $70.

View attachment 99790

  • Series: Trantorque OE
  • Component Bore Diameter: 32 mm
  • Shaft Diameter: 17 mm
http://www.fennerdrives.com/trantorque/_/Trantorque-OE-17mm/?s=ZnwyMzE4Oml8MTAyNA==
I used one of these on my Kubota.I bored a Love joy and used the Fenner to connect it to the 22mm shaft coming off the crank.Was able to find the needed size on ebay for $20. shipped.
 

Chucketn

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#23
Franko, I have a spare 1/2 x 13 LH tap if you need one. I bought a batch(new old stock) on E-Bay a while back. I've made a couple adapters for treadmill motors with them. All the DC PM treadmill motors I've collected have that thread on them. I made the pulley for the TM motor that runs my mill from the small end of it's flywheel.

Chuck
 

Franko

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#24
Interesting offer, Chuck. What sort of remuneration would you require?
 

Chucketn

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#25
Maybe trade for something you have extra?
I don't remember what I paid for the box of 5 taps, but it wasn't much.
PM me your address and I'll put one in the mail.

Chuck
 

Franko

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#26
Chuck, I can't PM you because it's turned off in your privacy settings.
 

Chucketn

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#27
Try again Franko. I think I turned it on.

Chuck
 

dpstanfill

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#28
I am new to hobby machinist, but I do have a tip here. In addition to the left hand 1/2 x 13 thread on tread mill motors, the pully issue is easily solved. Type L tempered copper has an almost perfect ID to fit the 17mm shaft ( usually less than .03 mm ie: an slight interference fit) While the OD is within +/-.001 of a 3/4" pully bore (makes an excellent no play bushing). I have used this trick many times in the past, and I will try to post pictures later.

Also I have successfully used multiple flats ground into the OD of the 17mm shaft and a machined Steel pulley with multiple set screws, even adding a third set screw (offset 60deg.).
 
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hman

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#29
I am new to hobby machinist, but I do have a tip here. In addition to the left hand 1/2 x 13 thread on tread mill motors, the pully issue is easily solved. Type M tempered copper has an almost perfect ID to fit the 17mm shaft ( usually less than .03 mm ie: an slight interference fit) While the OD is within =/-.001 of a 3/4" pully bore (makes an excellent no play bussing). I have used this trick many times in the past, and I will try to post pictures later.
OK, I'm a bit lost here. I assume you're talking about pipe, not fittings.

Went to http://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf and looked up pipe dimensions (Pages 62 thru 64 for K, L, and M). Parts of the tables for K, L, and M (with my labels) are reproduced below.

Nothing in the M table looks like it has and OD of ¾". However, both K and L pipes of nominal ⅝" size have ODs of .750". Of the two, it looks like L's ID of .666" is a better fit to 17mm (.669") than K's ID of .652". Am I missing or mis-reading something here?

Your tip is very useful, but I just want to be sure I get it right.

K Copper pipe dims.jpg L Copper pipe dims.jpg M Copper pipe dims.jpg
 

dpstanfill

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#30
Sorry, thanks for catching that it is Type L rigid but in 5/8 as the wall is nominal .042 though it seems to run closer to .0405 to .041 I have a piece in front of me that I just cut a bushing from and the ID Mich's at .669 and is a no slop slight interference fit for my motor shaft that I have on the bench, and the OD comes in at .751 (now where is my roll of 120 grit). Type M does not even come in 5/8 ID. As an added note Grainger down here stocks it in 2 foot lengths for $5.84 including tax. None of the big box stores seem to carry 5/8.

I edited my previous post to eliminate confusion.
 
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