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Thread: Wheel For Belt Grinder/Sander

  1. #11
    Senior Member HT1's Avatar
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    OK take everything I say as training not a critique please,

    if properly designed, I pulley should definitely not require any risers on the edge.. really the edge does not need to be thick at all so it should have a low mass, but if the solid spoke creates a large cross sectional thickness at the tee formed by the wheel edge you can get course dendrite formation which will weaken the structure, risering helps stop this, but it is a poor way of dealing with it, the better way is to limit the thickness of the web and the outer edge, this is alot of the reason for spokes or cast in holes in pulleys, think about it a heavy pulley is advantageous in many applications since it stores energy, making a light pulley negates this, but is required in the casting process... it looks cool done artistically also. My first image is a great lesson, this is one place a large fillet(radius) can cause shrinkage. as to the HUB, two options, core a hole in it or riser it. there are two gating options from the outside with a horseshoe shaped runner and multiple gates or a horn gate going to the hub... the horn gate puts hot metal under the riser so good, but horn gates are problematic in other ways. I would avoid that option... unless you have a space issue. (small flasks) as horn gates puts most of the gating system under the casting so you can reduce your flask size by several inches





    neat read here if a little off subject
    http://etraxx.com/projects/machinery...belt-pulley-i/

    V/r HT1

    P.S. so in short I agree with most of what has been said :-)

  2. #12
    HT1, Oh My... I want to do this correctly so any or all information is training for me, as long as my brain can take it in..

    So, your saying that I should use those formulas if possible for the wheels?

    and I should possibly lighten up the pulley and open up the middle cross section with some type of holes or spokes?

    All of this I can do, I am in no hurry, just want to do the best I can for an arthritic old man.lol

    Thanks HT1, I appreciate it..
    c

  3. #13
    Senior Member HT1's Avatar
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    Quote Originally Posted by corky View Post
    HT1, Oh My... I want to do this correctly so any or all information is training for me, as long as my brain can take it in..

    So, your saying that I should use those formulas if possible for the wheels?

    and I should possibly lighten up the pulley and open up the middle cross section with some type of holes or spokes?

    All of this I can do, I am in no hurry, just want to do the best I can for an arthritic old man.lol

    Thanks HT1, I appreciate it..
    c
    those formulas are nuked out .. do something simple draw how thick the web and the rim is in real scale add the fillet radius and inscribe a circle in it
    this reference and figure 113 will help,
    http://archive.hnsa.org/doc/foundry/part2.htm#pg104

    if your inscribed circle is under 7/8 inch you should not need a raiser at all if you keep the temperature at the bottom of the pouring range( IM ASSUMING Aluminium here). I would try it without a riser if the circle got up to say 1.3 Inch . at that point I would look a the design for changes . But if you decide it needs riser on the edge, they do not need to go on top of the casting if you centerline gate, you can feed through side risers that will perfectly feed your problem areas, though you will need 3-4 risers that route. but really the only place I would consider risering that til it got Hugh would be the center hub


    BTW Figure 137 is a nice reference for you, just be aware that piece is better then 2 ft in Diameter and is super thick, they probably intend on machining multiple belt grooves in it so it needs that heavy machining allowance, you do not have that issue .


    V/r HT1

  4. #14
    Quote Originally Posted by HT1 View Post
    those formulas are nuked out .. do something simple draw how thick the web and the rim is in real scale add the fillet radius and inscribe a circle in it
    this reference and figure 113 will help,
    http://archive.hnsa.org/doc/foundry/part2.htm#pg104

    if your inscribed circle is under 7/8 inch you should not need a raiser at all if you keep the temperature at the bottom of the pouring range( IM ASSUMING Aluminium here). I would try it without a riser if the circle got up to say 1.3 Inch . at that point I would look a the design for changes . But if you decide it needs riser on the edge, they do not need to go on top of the casting if you centerline gate, you can feed through side risers that will perfectly feed your problem areas, though you will need 3-4 risers that route. but really the only place I would consider risering that til it got Hugh would be the center hub


    BTW Figure 137 is a nice reference for you, just be aware that piece is better then 2 ft in Diameter and is super thick, they probably intend on machining multiple belt grooves in it so it needs that heavy machining allowance, you do not have that issue .


    V/r HT1
    I like all this info, it helps a lot to see how things work.

    Most of yesterday afternoon and evening I drew out a lot of pulleys, using those formulas, from 2" to 10", just for fun to see how they would actually look like, they look more normal than that big clumpy thing I made at first.

    And what I call spokes they call arms, they can get fancy if a person wants to go that way like you said.

    So back to work and starting anew, to see what I come up with.

    And I still haven't found my phone..Hmmmm

    Thanks alot and have a nice day.
    c
    If You Cant Be Handsome Ya Gotta Be Handy

  5. #15
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    Very interesting reading. I'm learning a lot from your thread. My sheave is a little different but there are lots of similarities.

    Thanks

  6. #16
    Quote Originally Posted by oldironfarmer View Post
    Very interesting reading. I'm learning a lot from your thread. My sheave is a little different but there are lots of similarities.

    Thanks
    Thanks
    If You Cant Be Handsome Ya Gotta Be Handy

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