04-24-2015, 10:55 PM
(04-24-2015, 04:37 PM)Pete O Wrote: Thanks for the responses. Regarding the apparent difference in the threads, it is a bit of an optical illusion- the acme threaded shaft is sitting flat on the bench, whilst the square threaded one is tilted due to sitting on the flange at one end. That and the fact that the crest of the square thread is so much wider than the crest of the acme. They are both 1" 5tpi.
Sorting through the replies, I'm hearing bore it to 5/8 as deep as the gear teeth, make the male section about .0025 oversize, shrink fit plus loctite. If I were to pin it, what sort of pin is used? How is this done?
If you heat it as per suggestions the Loctite will evaporate and I also think the 2 1/2 thousandths on a .625 shaft is extreme overkill. I was taught (years ago) to use .0005" to .001" per 1.0" of diameter. So at the outside I'd be using .0005" of interference. After wards I'd also pin it, probably with an appropriately sized taper pin.
An extremely good joint would include a straight knurl on the male part of the fitting at .001" or even a little more over the knurls. A diamond knurl will also work, but Lord help you if you get it started crooked. Shrink fit them together (heating the female part only) and it would be almost like they were welded. Freezing the male portion would not hurt.