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Thread: Machined Pulleys: How to Measure and Where to Purchase?

  1. #1

    Machined Pulleys: How to Measure and Where to Purchase?

    I've got a shaky Delta bandsaw with a wobbly drive pulley. The local service center had a replacement pulley, but it's only slightly better than the first one.

    When I spin the wheel by hand, I can actually see the pulley wobble. A link belt helped a bit, but it's still quite shaky. I can only assume the wobbly drive pulley is part of the problem since it doesn't shake much when I remove the belt and run the motor by itself.

    So, I've been looking into machined pulleys.

    First, I don't really know what to measure to ensure I get the right pulleys. Second, I have no idea where to pick one up. So I've spent a lot of time on google, but haven't become any less confused.

    If I measured the pulleys correctly (which I don't think I have), the drive pulley has a keyed 3/4" bore and a 4-5/8" OD and the motor pulley (which seems to be okay) has a keyed 21/32" (maybe 5/8") bore and a 2-13/64" (maybe 2 1/4") OD.

    Any help ya'll can offer is greatly appreciated!

    Paul
    Paul Fitzgerald
    Mid-South Woodworker and Turner


  2. #2
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    Paul -

    I'd call Louis Iturra down in FL....a delta band saw guru. A google should list his #... Iturra Designs.

    Secondly, try McMaster-Carr online.....lots of goodies from them available..

  3. #3
    Paul,

    Look for a bearing supply company or "power transmission" company. Any place with a service counter will be to help you out. They are used to folks dragging in a destroyed bearing or pulley and finding a suitable replacement. Prices are probably lower than your expecting, I just picked up a 6" machined pulley the other day. Cost, $13.75 out the door. No need to go mail order and "hope" you get it right with the added bonus of shipping costs!

    I see your in a suburb of Memphis, there are a number of bearing distributors in your area:
    http://www.superpages.com/yellowpage...-TN/T-Memphis/

    Mike

  4. #4
    Rob Will Guest
    Quote Originally Posted by M Toupin View Post
    Paul,

    Look for a bearing supply company or "power transmission" company. Any place with a service counter will be to help you out. They are used to folks dragging in a destroyed bearing or pulley and finding a suitable replacement. Prices are probably lower than your expecting, I just picked up a 6" machined pulley the other day. Cost, $13.75 out the door. No need to go mail order and "hope" you get it right with the added bonus of shipping costs!

    I see your in a suburb of Memphis, there are a number of bearing distributors in your area:
    http://www.superpages.com/yellowpage...-TN/T-Memphis/

    Mike
    What Mike said. The local bearing shop can help. Often right off the shelf.

    Rob

  5. #5
    I've taken vacation for the rest of the year, so I finally had time to go by a few bearing dealers.

    First, I called to find out which had counter sales. Half didn't sell to the public. I dropped by the rest.

    When I asked for machined pulleys, the first few shops said all they had were cast pulleys and they'd have to order the size I needed. They'd take at least two weeks to come in.

    The next place also only carried cast pulleys, but said they can have machined pulleys made, but they're a special order, would take 6-8 weeks to come in, and are twice the price of cast.

    And the last place I went to just looked at me like I was a moron.

    I really didn't expect "we don't stock those sizes" or "what's a machined pulley."

    I've looked at Grainger and McMaster-Carr, but they don't seem to have the right size.

    Any ideas?

    Paul
    Paul Fitzgerald
    Mid-South Woodworker and Turner


  6. #6
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    If your pulley is a 4 5/8" (4.625") outer diameter, you should be able to use a 4.45" or a 4.7" cast pulley (often referred to as sheaves) in its place. These are standard sizes for Browning pulleys, and their clones. The only difference is with the 4.45" pulley, your blade speed will be a little faster, and with the 4.7" pulley, it will be a little slower. This won't affect the running of your bandsaw too much, but I'd go with the smaller pulley, as a little extra blade speed is always good.

    FYI, the critical measurement is the diameter where the drive belt seats in the the groove, which is referred to as the pitch diameter, or sometimes working diameter.

    And in case you're worried about not replacing the pulley with an exact replacement, when I was rehabbing my old bandsaw, I replaced the pulleys on both the motor and drive wheel with pulleys of different sizes from the original to get the blade speed I wanted.

  7. #7
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    "machined pulley" is one of those terms that comes up on forums like this more than it comes up in actual shops. If a brand new Delta pulley has a noticeable wobble, it's time for some diagnosis.

    What's the history of this saw? Was there a time during your ownership of the saw when the pulley didn't wobble? Is it possible that the bottom shaft is bent, for example if the saw fell over? Is the shaft or keyway badly worn, filed, or damaged?

    To answer your original question, Grizzly has what you want. Your local electric motor rebuilder can get them too. You would just need to measure the bore and diameter of the pulleys that you have. However, you should get to the root cause of the problem before ordering or the pulleys may be no more successful than the link belts.

    Pete

  8. #8
    Quote Originally Posted by Wilbur Pan View Post
    If your pulley is a 4 5/8" (4.625") outer diameter, you should be able to use a 4.45" or a 4.7" cast pulley (often referred to as sheaves) in its place. These are standard sizes for Browning pulleys, and their clones. The only difference is with the 4.45" pulley, your blade speed will be a little faster, and with the 4.7" pulley, it will be a little slower. This won't affect the running of your bandsaw too much, but I'd go with the smaller pulley, as a little extra blade speed is always good.

    FYI, the critical measurement is the diameter where the drive belt seats in the the groove, which is referred to as the pitch diameter, or sometimes working diameter.

    And in case you're worried about not replacing the pulley with an exact replacement, when I was rehabbing my old bandsaw, I replaced the pulleys on both the motor and drive wheel with pulleys of different sizes from the original to get the blade speed I wanted.
    That makes sense. I don't have to match the sizes, as long as I get the blade speed I want/need.

    Do you know if you're supposed to calculate SFPM with the Outer Diameter or the Pitch Diameter?

    Quote Originally Posted by Pete Bradley View Post
    "machined pulley" is one of those terms that comes up on forums like this more than it comes up in actual shops. If a brand new Delta pulley has a noticeable wobble, it's time for some diagnosis.

    What's the history of this saw? Was there a time during your ownership of the saw when the pulley didn't wobble? Is it possible that the bottom shaft is bent, for example if the saw fell over? Is the shaft or keyway badly worn, filed, or damaged?

    To answer your original question, Grizzly has what you want. Your local electric motor rebuilder can get them too. You would just need to measure the bore and diameter of the pulleys that you have. However, you should get to the root cause of the problem before ordering or the pulleys may be no more successful than the link belts.

    Pete
    It's a brand new saw. The wheel shaft has less than 0.001" runout. The pulley itself has 0.018", which is enough for me to see it wobble. I don't see any issues with the keyway being worn, filed, or damaged.

    Delta will replace the pulley for me, but I figured I could pick up a better set of pulleys just as easily.

    I'll check Grizzly too... thanks for the tip!

    Paul
    Paul Fitzgerald
    Mid-South Woodworker and Turner


  9. #9
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    Befor replaceing the pulley, check the shaft to make sure it is not bent. This might seem odd, but there more chance of the shaft being bent then the pulley.

  10. #10
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    Like Al said ,check the shaft and make sure it's not bent. If it's not, Woodcraft has a replacement pulley and belt kit made for the Delta contractor saw. It's about $60 or so.
    Michael Gibbons

    I think I like opening day of deer season more than any udder day of the year. It's like Christmas wit guns. - Remnar Soady

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  11. #11
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    Quote Originally Posted by Paul Fitzgerald View Post
    It's a brand new saw. The wheel shaft has less than 0.001" runout. The pulley itself has 0.018"
    I'd be surprised if that little runout could cause serious vibration, even in a 14". Are you sure the wheels are ok? Have you run it without a band to make sure it's not coming from the top wheel? Just some more things to try.

    Pete

  12. #12
    Browning and other brands of cast iron sheaves are machined. Surplus Center has what you want.

  13. #13
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    Quote Originally Posted by Paul Fitzgerald View Post
    Do you know if you're supposed to calculate SFPM with the Outer Diameter or the Pitch Diameter?
    Ideally, you should use the pitch diameter. But the amount of error in this calculation is negligible. The range of useful bandsaw blade speeds for any given blade is pretty wide, so the difference between using the outer diameter and the pitch diameter becomes insignificant.

    For example, on my bandsaw, I have a BK36 (3.75" OD, 3.4" working diameter for a B belt) on the motor and a BK80 (7.75" OD, 7.40" working diameter). Using the working diameters, the SFPM is 3320 ft/min. Using the outer diameters, the SPFM is 3496 ft/min, which is just a hair over 5% difference. The amount your bandsaw motor slows down when you feed it that 8/4 chunk of white oak will have a much larger impact on the blade speed than that 5% error.

  14. #14
    Paul,
    A cast pulley is a machined pulley. It might seem a bit counterintuitive, but the cast pulley has to be machined to specs. if you look at one you'll notice, especially on the smaller ones, virtually the entire pulley is machined. It's true that you can get a shiny "machined" pulley made of steel, but you'll find that those pulleys are generally marketed towards the hobby WW community. The main intent is to remove a large wad of cash from your wallet rather than remove vibrations. A quality cast pulley will serve you just as well for a lot less.

    Mike

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