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Mechanics and Construction => Mechanics and Construction => Topic started by: corrado33 on May 17, 2012, 01:46:58 PM

Title: Will a 3mm shaft work well with a 1/8in bore? (Gah imperial units)
Post by: corrado33 on May 17, 2012, 01:46:58 PM

Many small DC motors have a 3mm output shaft, yet many small drive pulleys have a 1/8 inch bore.  Yes, the shaft will fit into the bore, but will the small difference in diameter produce undesirable results (uneven drive, shaking etc)?  Yes the bore does have a set screw, so I'm sure it'll be held tight.  Is there any way around this? 

Yes, I know if it was the other way around (1/8 in shaft with 3mm bore) I could simply bore it out, but I can't in this case. 

Title: Re: Will a 3mm shaft work well with a 1/8in bore? (Gah imperial units)
Post by: tomcharley on May 23, 2012, 11:43:56 AM

Dear Corrado,

  Could you maybe pad the other edge of the bore with something to even out the unevenness caused by the set screw?  A piece of paper or two could do the trick (copy paper is ~.004" thick).  If you do use paper, it will crush a little, so you'll be able to make sure that the output shaft is centered in the bore by adjusting the tightness of the set screw.  If you need something a little more durable, you could use foil instead.  Standard household aluminum foil is ~.0006" thick, so you'll need a few more sheets.
  This might not work if the drive pulley is being alternately pushed and pulled along its axis because the padding might eventually work itself free.

~Tom