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  • Mike Amick
    replied
    Thanks John ... After all, I have decided to not use the old motor pulley. I am going
    to use a var speed set up that will allow me to forgo the need for the step pulley.

    I have started another thread asking opinions on how fast you can run these big pulleys ..

    Sorry for the false alarm .. but .. to tell you the truth, the education on shaft lengthening
    was well worth it.

    Leave a comment:


  • John Stevenson
    replied
    Problem with that motor in the picture is that it has a smaller bearing than the final shaft diameter so a setup up isn't going to be successful.

    The shaft cannot be pressed out of a DC motor without causing a rewind as the comm and rotor are two separate entities and when you press them out you squash the windings inbetween the two.

    If I had to do this I would turn the shaft down 1/16" undersize including where the bearing sits, then drill the end about 5/16" for 1" deep, not critical and drive a tight fitting steel pin in equal to the length you need plus a bit.

    I'd then weld the whole lot up, pin as well to get an oversized welded slug on the end.
    Support in a steady, face the end, centre and machine to original size but to the length you want.

    THEN sleeve the pulley to match, about an hours job not allowing cooling times from welding.

    Leave a comment:


  • garyhlucas
    replied
    Seeing the motor and pulley I don't think I'd weld it. I'd make a new sleeve extension to fit over the new motor shaft. That might mean I'd need to bore the step pulley for a slightly larger size like 1". But then the motor is replaceable without welding in the future. Make a 1" sleeve with a 5/8" bore.

    Leave a comment:


  • The Artful Bodger
    replied
    I swear BK they bl**dy well do!

    Last week we were negotiating with an Air Force museum to get some gun muzzles to finish off one of the aircraft we have on display in our museum. They brought out one and remarked "See, there is nothing to them, you could have some made". Within minutes I was compulsorily volunteered to make some for us and for other museums too. My shop is now knee deep in aluminium swarf and I have a nice carton of muzzle brakes for Hispano 20mm aircraft cannons!

    Leave a comment:


  • Black Forest
    replied
    Originally posted by The Artful Bodger View Post
    Ha ha! I hope someone says that about me one day!
    What are you talking about! They're already saying that about you. Hey take it to that old fart John, he fixes stuff up pretty good.

    Leave a comment:


  • digr
    replied
    When I did mine I welded a larger than needed extension shaft on (beveled for 100% weld) the armature and then set it up in a four jaw on the lathe centered it, drilled a center hole and turned it down to the proper size. The extension shaft was large enough so I didn't have to worry about getting it that close to true.

    Leave a comment:


  • lakeside53
    replied
    Bore one out, male equiv on the other, v around both edges, press together, weld up, run down. Put a center on the extension first to make it easier to turn, or use a steady on the bearing surface.

    Leave a comment:


  • Mike Amick
    replied
    Ok .. here is a pic of the big ol OEM .. with the long shaft and the
    other armature.



    and again ... how do I hold the shafts to weld them. If I use regular v blocks
    they wont be centered, unless I maybe shim the small size to get it in the
    middle of the big shaft.

    Might have to give wilson idea a try.

    Mike

    Leave a comment:


  • WilsonT
    replied
    It seems to me that if you are changing from a 5/8 shaft to a 3/4 shaft, it would not be necessary to turn the 5/8 shaft down. Just mill the flat spot. Drill/bore a 5/8 hole in the 3/4 shaft, then mill the slot, slide them together and weld. You might even use heat/cold to get a shrink fit.

    Leave a comment:


  • John Stevenson
    replied
    Well when you decide what motor you are using post some pictures as not all motors are equal and it's sometimes easier to do two motors two different ways.

    Bearings could be metric as they are usually cheaper, tend to go 15mm, 17mm, 20mm then jump to 25mm

    Leave a comment:


  • Mike Amick
    replied
    Originally posted by John Stevenson View Post
    Silly question but if you are going up from 5/8" to 3/4" what bore size is the front bearing ?
    I haven't taken the new motor apart. Truth is .. I'm not sure which motor I will be using.

    I am replacing the 1hp 3ph OEM on the Millrite I am working on. When I hook it up to the
    static ph converter it surges, surges surges ..then sometimes gets going sometimes not.
    Also the bearings are noisy. But overhauling it is not out of the question. It has a long
    .75 shaft to into the thick step pulley.

    I also have 1hp 3ph motor with a .875 much shorter shaft.

    And I have several large 3hp treadmill motors and controllers with 5/8 shafts also shorter.

    I have a lot of experience with the treadmill stuff and am leaning that way. I know a VFD
    on the 3ph is a nice option as I have that on my Cincinnati mill.

    But to answer your question John, the shaft needs enlarged to fit the pulley. I can only
    assume that the 5/8 shaft has a bear ID of 5/8 .. grin

    Mike

    Leave a comment:


  • Jaakko Fagerlund
    replied
    Originally posted by mikeamick View Post
    Ok .. interesting. I welded up an old vice and tried to mill the weld smooth. Broke a bunch
    of EM's I always thought it was the weld it self that was hard (mig welding) I am way not
    afraid to give it a try on the shaft though ..
    Vice is made of mystery metal and can't know for sure what it is, as I've seen them made from cheap structural steel as well as from prehardened stuff and some high carbon stuff also. If you go and weld high carbon content steel or other highly alloyed, the weld and the area around it will most probably become hard as hell.

    But if you weld structural steel (S235 or S355), there is no distinguishable difference in the hardness when machining it.

    Leave a comment:


  • John Stevenson
    replied
    Silly question but if you are going up from 5/8" to 3/4" what bore size is the front bearing ?

    Leave a comment:


  • Mike Amick
    replied
    Oh .. one more quick thing. What is the age ol way of aligning the new shaft with the
    old shaft for welding ?

    Leave a comment:


  • Mike Amick
    replied
    Originally posted by Jaakko Fagerlund View Post
    If the shaft is plain old S355 and not some highly alloyed, the welding isn't going to harden it. Every weld I've machined has been soft as peanut butter in the lathe, the only issue being some interrupted cutting as the weld is not symmetrical or round.
    Ok .. interesting. I welded up an old vice and tried to mill the weld smooth. Broke a bunch
    of EM's I always thought it was the weld it self that was hard (mig welding) I am way not
    afraid to give it a try on the shaft though ..

    Originally posted by jlevie View Post
    Reduce the diameter of the 5/8 part, bore the 3/4 part, and heat shrink the two together.
    Thats why I come here .. lol Can't believe that thought didn't come to me. Just steal a
    little meat from the smaller shaft help the integrity.

    Ok .. I think I am going to go what appears to be the traditional route. I'll weld prep the
    shafts and weld. Also .. as per the great suggestion, I will use a shaft that is larger than
    needed so I can straighten and smooth.

    Thanks
    Mike

    Leave a comment:

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