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27th Mar 2014, 12:07 AM #1New Member
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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
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27th Mar 2014, 07:00 AM #2Philomath in training
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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
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27th Mar 2014, 08:37 AM #3Most Valued Member
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27th Mar 2014, 01:18 PM #4Philomath in training
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27th Mar 2014, 07:26 PM #5New Member
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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
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27th Mar 2014, 08:41 PM #6New Member
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Double post
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27th Mar 2014, 08:45 PM #7Most Valued Member
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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
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28th Mar 2014, 09:09 PM #8New Member
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"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
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29th Mar 2014, 03:28 PM #9Product designer retired
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AB where are you?
Anorak Bob, got your ears on?
You are probably the closest if you can help out.
Ken
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29th Mar 2014, 04:49 PM #10Diamond Member
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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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