Today in the shop (turning problem)

skou · Post by **skou** » Thu May 29, 2014 12:44 am

Ed, if you just need to get your machinist to duplicate that "pop," any SS spindle should work. Even a model 10 spindle.

Oh, one more suggestion, get a tiny amount of some light oil in that adapter hole. I'll bet you get the "pop."

I've had arbors that would actually push back off, when installed, because of the tight fit. Had to hold them on, while tightening the setscrew. My drive spur does that.

steve

JPG · Post by **JPG** » Thu May 29, 2014 1:34 am

0.625 -0 +.002 with a bore depth of 1.200 should pop. The shaft is 0.623. All that I measured but with older ones a smidgen smaller.

The bore depth will affect the pop. Too shallow and the tapered flat will leak air. Too deep and the air inside will not allow sufficient vacuum to pop.

Also a loose fit of the setscrew could(not likely) provide a leak.

skou · Post by **skou** » Thu May 29, 2014 2:30 am

Ed, JPG, that "pop" isn't really all that important. The fit is.

I've seen spindles where the tapered flat has been cut too deep, and you've got an air leak at the very tip. (We're talking 2 or 3 thousandths, nothing to worry about.) But, with that air leak, even though you're still mounting an attachment coaxial (both have the same axis) to the spindle, you won't get the "pop."

OK, here I get to eat some crow. I just played with the ER set up in the front room, and it seems that I can pull an arbor off, get the pop, but cannot turn the arbor all the way around, on the spindle, with the setscrew in the same position. In other words, the taper extends (barely) past the end of the spindle, but I can still get a pop. I also feel (compression) resistance, when pushing on the arbor.

It takes some playing with the setscrew, (and this one is too long, so I can do it by hand) but there is a setting where the setscrew will allow the arbor to come off, but not to spin on the spindle.

Oh, it's nice to have all 3 real long Allen wrenches for the ER. Never had them before, and removing a sanding disc was, uh, "fun" at best.

steve

JPG · Post by **JPG** » Thu May 29, 2014 11:53 am

skou wrote:Ed, JPG, that "pop" isn't really all that important. The fit is.
. . .
I would add axial alignment.]

Oh, it's nice to have all 3 real long Allen wrenches for the ER. Never had them before, and removing a sanding disc was, uh, "fun" at best.

steve

I welded two 'regular' wrenches(butt joint) to get a longer one before I got one, but still use oem ONE that I (now) have.

reible · Post by **reible** » Sat May 31, 2014 4:01 pm

I'm sorry if I confused matters with the "pop". This was merely a term of endearment to the fit that shopsmith has. That in mechanical engineering terms is like saying a pinch of salt to a cook.

While in cases the fit can be established by use of design there are other times when we have things like the actual size and tolerance of of the shopsmith shaft and the arbors that fit the way they do. Shopsmith does not give that information nor are they likely to share anytime soon.

This leaves us with doing things like measuring. Now you have your calipers, I have my caliper, the machinist has a set....... add in how well a person uses them and well you can be off more then the fit will allow. I personally have an expensive version that reads to four places to the right of the decimal point. I had that for work so it was reasonable to spend the money on a one that good. It stays in its case most of the time now but if the batteries are still good (stored out of the instrument) I could still use it to do some pretty precise measurements. But if the other party involved has one from HF what good does it do?

Far and away the best way to get what I want is to send a real live shopsmith shaft and let the machinist do the fit. You will have to trust me on this.

I'll be wrapping up the shaft to send out on Monday so a few days to get there then a few days to have the two made and a few days back to me. Should be plenty of time to have them in hand before my trip up to see my brother.

Ed

JPG · Post by **JPG** » Sat May 31, 2014 4:29 pm

reible wrote:I'm sorry if I confused matters with the "pop". This was merely a term of endearment to the fit that shopsmith has. That in mechanical engineering terms is like saying a pinch of salt to a cook.

While in cases the fit can be established by use of design there are other times when we have things like the actual size and tolerance of of the shopsmith shaft and the arbors that fit the way they do. Shopsmith does not give that information nor are they likely to share anytime soon.

This leaves us with doing things like measuring. Now you have your calipers, I have my caliper, the machinist has a set....... add in how well a person uses them and well you can be off more then the fit will allow. I personally have an expensive version that reads to four places to the right of the decimal point. I had that for work so it was reasonable to spend the money on a one that good. It stays in its case most of the time now but if the batteries are still good (stored out of the instrument) I could still use it to do some pretty precise measurements. But if the other party involved has one from HF what good does it do?

Far and away the best way to get what I want is to send a real live shopsmith shaft and let the machinist do the fit. You will have to trust me on this.

I'll be wrapping up the shaft to send out on Monday so a few days to get there then a few days to have the two made and a few days back to me. Should be plenty of time to have them in hand before my trip up to see my brother.

Ed

FWIW, I used a B&S micrometer!;) Those digital calipers are ok for approximating.