Drive pulley source ?

[Rick Fisher]

Does anyone have a good online source for double v-belt, machined drive pulleys?

I may be googling the wrong words?

I found some on Grizzly, but nothing with an 1 1/8" hole.

There must be some company that has a huge selection of these things?

I need a 3 1/2" ID Drive pulley of good quality. Measured inside to inside. With a 1 1/8" Hole for a 184T nema frame motor.

Its really a simple request :)

[Rick Fisher]

Perhaps someone mathmatically inclined could check these figures.

My bandsaw has a history of being a serious blade breaker, the evidence is everywhere and it was written on the saw in black felt marker.

It has a 1700 RPM Motor with a 5" drive pulley, a 10" run pulley and 23.5" wheels.

The motor, and drive pulley (I suspect) are not origional.

I calculate a S.F.P.M of 5226. (surface feet per minute). If the motor is actually 1725 rpm. Then of course its more?

Most all bandsaw blades are rated for no more than 4000 SFPM. So I suspect that this is a good place to start.

A 3.5" drive pulley would reduce the SFPM to 3712 SFPM, if the motor is 1725 rpm.

If anyone thinks I am on the wrong track here, let me know.

The blades are 15' long. I am repairing all the damage and the idea of a blade letting go would be discouraging.

[Tom Veatch]

...It has a 1700 RPM Motor with a 5" drive pulley, a 10" run pulley and 23.5" wheels. ...

Assuming the Pitch Diameter (PD) of the pulleys is about .5" less than the OD, and no slippage on the belt(s):

1700 RPM on a 4.5" PD drive pulley would yield 1700*4.5/9.5 = 805.3 RPM on the run pulley (9.5" PD).

Assuming the run pulley is rigidly attached to the wheel, the wheel would also turn at 805.3 RPM.
A 23.5" diameter wheel has a circumference of 23.5*Pi inches = 73.83".

Each revolution of the wheel moves the blade 73.83" so the Blade FPM = (73.83 * 805.3)/12 = 4955 fpm.

If the motor is 1750 RPM which is likely, the blade FPM becomes 5101.


To get the FPM down to 4000:
keep the existing drive pulley and replace the run pulley with one that has a 12.16" PD or larger, or
keep the existing run pulley and replace the drive pulley with one that has a 3.5" PD or smaller, or
replace both pulleys with a pair in which the drive pulley PD is no larger than 37% of the run pulley PD.

[Pete Bradley]

5000 FPM is on the high side, but not out of the question for a machine of this size. My 20" industrial machine was designed for 4500 FPM.

Does it break blades for you? What are you using for bands and tension settings?

Are the wheels reasonably coplanar (within 1/8 or so at the sides)? They don't have to be dead on, but I can imagine that if they were way out, that might accelerate band failure.

Pete

[Wilbur Pan]

Perhaps someone mathmatically inclined could check these figures.

A 3.5" drive pulley would reduce the SFPM to 3712 SFPM, if the motor is 1725 rpm.


Your math is right on. But don't worry about the exact SFPM of your blade. As long as you are below the rated maximum speed of the blade, there's a huge range of usable blade speeds, so being off by 50 or so won't matter.

I've read that if you have a choice between two pulley combinations, you want to go with the combination that puts a smaller pulley on the motor.

One of these (http://www.surpluscenter.com/item.asp?UID=2008090407444978&item=1-2BKH45&catname=powerTrans) and one of these (http://www.surpluscenter.com/item.asp?UID=2008090407444978&item=1-2913-125&catname=powerTrans) should get you set up (total cost about $15), assuming that you're using an A type v-belt..

[Joe Meazle]

Surplus center is where I was going to to send you too. Did you get a new Motor? what did you get?

[Kirk Poore]

To buy locally, you can look up "power transmission" under your yellow pages. McMaster-Carr (http://www.mcmaster.com/) or MSC Direct (http://www1.mscdirect.com/cgi/nnsrhm) will have some on-line. Search for sheaves. Your best bet is a two-part pulley--an outer pulley with a tapered bore sized to you shaft. Not cheap, but paying for quality here is worth it.

5200 SFPM doesn't seem too fast to me. I think your breakage problem lies elsewhere.

Kirk

[Curt Harms]

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=17623397&PMT4NO=48892430.

or this:http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2248379&PMT4NO=0

MSC has a pretty good selection of pulleys.

HTH

Curt

[Cliff Rohrabacher]

Does anyone have a good online source for double v-belt, machined drive pulleys?

http://www.martinsprocket.com/home.htm

http://www.powertransmission.com/cgi-bin/newleads.cgi?Sheaves

[Rick Fisher]

You guys are all a great help.

This saw was purchased sight unseen in an online auction.
The lower guides where missing completely, yet they where still running the saw.

At first, I thought the breakage was due to no lower guides. The inside of the saw has extensive evidence of broken blades. There are tears in the lower door where the blade has broken and struck the door.
The table insert is gone and they replaced it with an oak one. The oak one is trashed, blade marks everywhere.

The tires are scored from what I can only assume is an errant blade dancing around inside the machine.

So I started wondering why they took the lower guides off? Did the guides get destroyed by a blade as well?

The speed which I calculated doesnt match the speed given by SCM. So something is not origional.

[Rick Fisher]

So I took some of the advice offered. Surplus supply has exactly what I am looking for, for $10.00 :)

I came up with a funny.

Finding out you need new knobs, tires, pedal and other parts. $200.00
Finding out you need new guides and mounts .... $300.00
Finding out you need a new motor and mag switch $700.00

Buying a used Italian machine at an online auction, sight unseen....

PRICELESS... :)

[Rick Fisher]

I need a double pulley. Problem is that all these pulley's have an overall width of 1.75".
The idler pulley is actually part of the lower bandsaw wheel so its permanent. The width of my drive pulley and idler pulley are both 1.25".



http://i335.photobucket.com/albums/m455/jokerbird_photo/IMG_0943.jpg

Looks like my search is still underway.

[Joe Meazle]

Rick,
My motor runs at 1680 RPM (If my Italian is right);)

[Wilbur Pan]

Looks like my search is still underway.

Do you have a picture of the motor pulley? Also, what kind of belt does your bandsaw use? That may be a good starting point in terms of looking for a replacement pulley.

[Curt Harms]

So I took some of the advice offered. Surplus supply has exactly what I am looking for, for $10.00 :)

I came up with a funny.

Finding out you need new knobs, tires, pedal and other parts. $200.00
Finding out you need new guides and mounts .... $300.00
Finding out you need a new motor and mag switch $700.00

Buying a used Italian machine at an online auction, sight unseen....

PRICELESS... :)

At least for the motor, is it a weird base, or are there other strange mounting characteristics? If not, you should be able to beat $700.

[Rick Fisher]

The motor portion includes a new Mag switch and pulley.

A Baldor 5hp 1725 is $545 up here. (In Canuckistan) :)
Mag switch $100.00
Pulley $??

The V-belts are 1/2 x 5/16 TxH. The Drive pulley has a 1" bore, it appears that it could be a tapered shaft and tapered fitting?? This is all new stuff to me.

[Wilbur Pan]

From the dimensions you gave, it looks like your v-belts are a standard A series v-belt. If that's the case, you don't have to worry about the outer width of the pulleys being the same. All that needs to happen is that the grooves themselves line up, and I'm pretty sure that the spacing for double grooves is pretty much standard.

I doubt that a taper by itself would be used to hold the pulley onto the motor shaft, especially with a 5 HP motor. Usually there is a key, or a tapered bushing with a split in it so that the bushing clamps down onto the drive shaft, and the pulley wheel bolts onto the bushing.