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  1. #1
    Join Date
    Mar 2014
    Location
    Australia, Perth
    Posts
    4

    Default Need some assistace with small project

    hello, new to this forum here, i was recomended to post here by a friend to see if i could find someone to help me. i have two small pulleys that need moddifying but i dont have access to a lathe or mill.



    the ID is currently .125" but i need it bored to .158"

    if there is anyone close buy that could help me out or point me in the right direction would be greatly appreciated, cheers

    would be more than welcome to throw a bit of cash or some beers if anyone can do it for me

  2. #2
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
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    6,541

    Default

    Hmm. The bore you are chasing still is not big. However, if no one closer sticks their hand up, I'll give it a go with the assistance of Aus post. What does the pulley go on? Does the bore have to be 0.158" spot on or is there a tolerance band (+/- 0.002 or +/- 0.004 or...)

    Michael

  3. #3
    Join Date
    Jun 2011
    Location
    Australia east coast
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    71
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    2,713

    Default

    Quote Originally Posted by Michael G View Post
    Hmm. The bore you are chasing still is not big. However, if no one closer sticks their hand up, I'll give it a go with the assistance of Aus post. What does the pulley go on? Does the bore have to be 0.158" spot on or is there a tolerance band (+/- 0.002 or +/- 0.004 or...)

    Michael
    Sounds like it needs a 3.5mm drill bit followed by a 4mm reamer to me.... or possibly just a 4mm new drill bit depending on tolerance.

    One assumes the current hole is actually on centre so all it needs is to be opened out.

    PDW

  4. #4
    Join Date
    Oct 2011
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    Norwood-ish, Adelaide
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    59
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    Default

    Quote Originally Posted by PDW View Post
    Sounds like it needs a 3.5mm drill bit followed by a 4mm reamer to me.... or possibly just a 4mm new drill bit depending on tolerance.
    That was the plan...

    Michael

  5. #5
    Join Date
    Mar 2014
    Location
    Australia, Perth
    Posts
    4

    Default

    The current hole is centered yes , its to fit onto an electric motor the shaft of which is the measurement in the first post, I presume there should be a little bit of tolerance but not too Mich. I shouldn't need to press the pulley onto the motor but it should slop either

  6. #6
    Join Date
    Mar 2014
    Location
    Australia, Perth
    Posts
    4

    Default

    Double post

  7. #7
    Join Date
    Jun 2011
    Location
    Australia east coast
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    71
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    Default

    Quote Originally Posted by Steven L View Post
    The current hole is centered yes , its to fit onto an electric motor the shaft of which is the measurement in the first post, I presume there should be a little bit of tolerance but not too Mich. I shouldn't need to press the pulley onto the motor but it should slop either
    Have you checked that shaft dimension with a micrometer or at least a decent set of vernier calipers?

    The difference between 'a little bit of tolerance' and 'should not slop' is an entirely subjective call I'm afraid. I'd say the hole should be in the range 0.001" to 0.002" over shaft diameter at most, and to hit that tolerance, one has to know what the shaft diameter actually *is* (and how it was measured if the person making the fit didn't do the measurement themselves). You haven't said this, only what size you want the hole to be, but with no tolerance band.

    I'm not trying to be picky, these things are important to getting a satisfactory job. It's unlikely in the extreme that anyone here is going to bore/drill/ream a hole exactly, precisely 0.15800". It'll be somewhere between 0.157" to 0.159". A 4mm reamer is 0.1574" so I suspect your shaft is actually 4mm, FWIW. A sharp 4mm drill bit *should* be good enough, a 4mm reamer probably perfect.

    PDW

  8. #8
    Join Date
    Mar 2014
    Location
    Australia, Perth
    Posts
    4

    Default

    "Preferably use a 4mm reamer - then you won't have to worry about it. If someone needs a tolerance for helping you tell them the size we're shooting for is .1575"-.159" absolute max - don't want much outside of that range. The actual motor shafts are .1576" by my measurement. .1575" may be a little tight, you might have to warm the pulley just a tiny bit to get it on. So target .158" as ideal".

    qouted from a friend on another forum that has done mod, he is a machinist (outside AU) so ill take his word on it

    sorry for tha lack of info i didnt realise how specific the measurement needed to be in order to machine it

  9. #9
    Join Date
    Nov 2006
    Location
    Heidelberg, Victoria
    Age
    79
    Posts
    2,074

    Default AB where are you?

    Anorak Bob, got your ears on?

    You are probably the closest if you can help out.

    Ken

  10. #10
    Join Date
    Mar 2011
    Location
    Dural NSW
    Age
    82
    Posts
    1,203

    Default Can assist if required

    I can assist if there are no other takers.
    Thought I had an oversize reamer but no luck, however I do have a set of "Number Drills" that could accomplish this task.
    Operations......
    Hold in collet in lathe.
    Centre drill the existing .125" dia hole first, to provide an accurate lead in for the drill.
    A "Number 25 drill is .1495" dia
    Follow that with a "Number 22 drill at .157" dia (to perform as a reamer).
    That should finish on size or possibly .1575" dia which should be spot on.
    Please lets know ?
    regards
    Bruce
    ps Best to do a trial run first on a seperate piece of brass.

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