Fall project... circa 1976 500 rebuild

enyoc · Post by **enyoc** » Mon Nov 04, 2013 7:56 am

JPG40504 wrote:What speed are you turning them at?

The bench tubes are not nearly as precise, so I turned them at the lowest speed of the Rikon mini: 430.

The way tubes are much better balanced, I felt comfortable at 810.

JPG40504 wrote:Put a threaded coupler on the threads and chuck that hex shape in the chuck.

There is a plain section prior to the threads, the drill chuck is quite secure. Not sure it's necessary, and not sure where to find a reverse threaded coupler of the right size. It looks 'spindly' but it's quite a strong connection, plus I am letting the abrasives do the work and not applying a lot of pressure.

JPG · Post by **JPG** » Mon Nov 04, 2013 10:55 pm

enyoc wrote:The bench tubes are not nearly as precise, so I turned them at the lowest speed of the Rikon mini: 430.

The way tubes are much better balanced, I felt comfortable at 810.

There is a plain section prior to the threads, the drill chuck is quite secure. Not sure it's necessary, and not sure where to find a reverse threaded coupler of the right size. It looks 'spindly' but it's quite a strong connection, plus I am letting the abrasives do the work and not applying a lot of pressure.

A coupler is not 'reverse' threaded. It is essentially a long nut. It is hex shaped like a nut, is threaded all the way through the center like a nut, but is more than 4x longer than a nut.

In this case it would allow the chuck to grip the larger hex shaped outside of the coupler while the inner threads attach securely to the 'pipe gripper'.

That said, I am thinking of a 'freeze' plug 'pipe gripper'. Your 'pipe gripper' may be different.

enyoc · Post by **enyoc** » Tue Nov 05, 2013 10:42 am

JPG, my pipe gripper is a sanding drum like

http://amzn.com/B002LVUWO0

... and is reverse threaded

JPG · Post by **JPG** » Tue Nov 05, 2013 1:26 pm

Tis the 'reverse threaded' words that confuse me.

I bet the shank has 'normal'(right handed) threads and a 'normal' threaded interior bore and a normal nut. When the nut is tightened(rotated clockwise) the interior causes the rubber to expand.

If the threads were 'reversed'(left handed), the rotaton of the shaft would tend to back the shaft out from the interior parts thus making the rubber smaller etc.

I Agree the smooth shaft is adequate in this case.

enyoc · Post by **enyoc** » Tue Nov 05, 2013 4:19 pm

think about which side the nut is on... they are left handed, bassackwards, wrongwaycorgan threads, else the load against a clockwise rotation would loosen the nut.

JPG · Post by **JPG** » Tue Nov 05, 2013 5:19 pm

enyoc wrote:think about which side the nut is on... they are left handed, bassackwards, wrongwaycorgan threads, else the load against a clockwise rotation would loosen the nut.

Methinks oppositely.

Now I be assuming assuming the the shaft threads into that core part that causes the rubber to expand and the nut pulls that.

However 'if' the movable internal 'expander' is not threaded and the hub is, then a left hand thread is appropriate.

Since you are adamant, I now assume the latter. However, how is the shaft turned to adjust the rubber size? Slot in the shaft(either end) or 'head' on the 'inner' end?

enyoc · Post by **enyoc** » Tue Nov 05, 2013 7:35 pm

here, disassembled, is a picture of the lefty-tighty, righty-loosy little bugger...

the head of the 'bolt' is plain (no slot, just smooth)

enyoc · Post by **enyoc** » Tue Nov 05, 2013 7:43 pm

JPG40504 wrote:how is the shaft turned to adjust the rubber size? Slot in the shaft(either end) or 'head' on the 'inner' end?

the shaft isn't turned, it's chucked then the nut is tightened with a 7/16 wrench.

JPG · Post by **JPG** » Tue Nov 05, 2013 10:28 pm

Well that certainly removed all confusion! Thanks.

Amazing how 'all' the details makes understanding easy!:)