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Cutting a V-Grove Pulley

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  • donf
    replied
    The third time is a very good result. I made a pulley for the alternator after the crank pulley and that came out on the first try. Thanks for all who gave advice the boring bar in the Bridgeport worked excellent for making a keyway. I have about $25 dollars in scrap in the first two tries, so not a big deal at all and learning a few more skills at the same time.

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  • donf
    replied
    Thank you for the feed back. I will order an old fashioned boring bar and grind a bit to make a 4.4 mm cut. I have two scrap pulleys to practice on so I can cut keyway in several spots to get the process refined. I think the third one will be a keeper.

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  • Richard P Wilson
    replied
    Originally posted by donf View Post

    Genius! No one else would have thought of that. I would have done that but a cnc run requires at least 15 or 20. I got 4 other orders so that group buy failed. I have been trying to buy one used but production stopped 25 years ago. The 4.4mm size broach is odd. I called around to machine shops today and no one has it. As it is the raw stock cost me about $13 per pulley purchased rough cut to size, so its just time. I got it close using two parting blades stacked together sideways and used the compound on the lathe. I got 90% there on this one but I did mess up the keyway I cut too much. Looks like I get more practice.
    I've managed keyways by regrinding a boring tool so the cutting edge is vertical, then racking it through the bore. Its best ground so it cuts on the 'pull' stroke, not the 'push' stroke, you get less chatter that way. You wouldn't want to do it often, or on tough materials, but on aluminium it will be fine. 'Some jobs are best left to those who are equipped to do them' Pah!

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  • Richard P Wilson
    replied
    Originally posted by ezduzit View Post

    Some jobs are best left to those who are equipped to do them.
    Most of the fun of a home shop is managing to do a job that by most standards you are not equipped to do! IMHO

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  • donf
    replied
    Originally posted by ezduzit View Post

    Some jobs are best left to those who are equipped to do them.
    Genius! No one else would have thought of that. I would have done that but a cnc run requires at least 15 or 20. I got 4 other orders so that group buy failed. I have been trying to buy one used but production stopped 25 years ago. The 4.4mm size broach is odd. I called around to machine shops today and no one has it. As it is the raw stock cost me about $13 per pulley purchased rough cut to size, so its just time. I got it close using two parting blades stacked together sideways and used the compound on the lathe. I got 90% there on this one but I did mess up the keyway I cut too much. Looks like I get more practice.

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  • Jim Stewart
    replied
    Originally posted by ezduzit View Post

    Some jobs are best left to those who are equipped to do them.
    Not a helpful comment.
    -js

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  • David Powell
    replied
    As you have already shown thought and patience I would think the keyway would just be a little extra challenge.Go for it, as you suggested, when you get near you might be able to sharpen a piece of keystock and use that as a primitive broach to take out the last couple of thous.Regards David Powell.

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  • ezduzit
    replied
    Originally posted by donf View Post
    ...I still have to figure out how to make a 4.4mm keyway cut. I am thinking a small end mill and a file to get the edges square.
    Some jobs are best left to those who are equipped to do them.

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  • donf
    replied
    Mostly done with a new crank pulley to slow things down at higher rpm. I still have to figure out how to make a 4.4mm keyway cut. I am thinking a small end mill and a file to get the edges square.

    Attached Files

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  • donf
    replied
    Holding it in the 4 jaw chuck worked a lot better! Thank you for the advice! This one is not done yet but its made it a lot farther than the first try.
    Attached Files

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  • Ridgerunner
    replied
    My method is to turn the outside to diameter. Drill for a center and then do the grooves first. This way the center helps resist side pressure while doing the grooves. Finish any features on that side on the pulley and then bore the center. Lastly, part it off and if necessary flip the pulley and face or machine any features on the other side. At least this way I feel the grooves are concentric with the bore.

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  • mattthemuppet
    replied
    Originally posted by The Metal Butcher View Post

    Or finish the hub and then turn all the V-groove features and the bore. First option has better holding power though. Either way, there is no reason to use an expanding mandrel on this. It will only make a worse part.
    that was the problem that I had, not much holding power by gripping the hub. Had to re-true it in the 4 jaw a few times before hitting on the "part cut the Vs then go back and finish them all" approach.

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  • Stepside
    replied
    Take a new V-belt and bend it in the arc about the same size as the sheave/pulley you are going to use. You should see the sides of the belt bulge outward. The belt attempting to bulge is what gives it traction. Or look at a worn out belt and you will see the sides are concave instead of straight. A worn out pulley/sheave will not have straight sides but will be concave as well.

    The angles are not as critical but should be close. The belt should never touch the bottom of the groove.

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  • Richard P Wilson
    replied
    Its isn't that difficult. I recently made several vee belt pulleys from aluminium stock, ranging from 2" OD to 7 1/2" OD, on a 100 year old 8" lathe (4" centre height) I'd chuck the stock, turn the vee profile, do the bore (Drill, bore, finish ream), then turn over and do the hub. Doing the vee, I ground a profile tool from a 1/2" HSS blank, roughed out the groove to full depth with a parting tool, then went in with the profile tool, one side at a time, until it was just shaving full width, full depth.

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  • donf
    replied
    Thank you for the education. I will give it another shot this week sometime.

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