Sheepscot Turntable - Official Work Thread

[Bob Holmes]

How will ring rails and center pivot be attached to the concrete?

[Gordon Cook]

I noticed in the picture of the pivot casting that it had a hemispherical shape. Then in the picture of it installed that shape has been machined to be flat on the end.
Way back when, many turntables for playing records had a center pivot with a hemispherical shape on the end because that shape in a flat bottom cup created a thrust bearing with the least friction and noise. It also allows for slight misalignment.
I had 'assumed' that would be true in this case as well when I saw the round shape of the pin.
Can someone explain why the pin would be cast with the round shape and then have that machined off?

[Jason M Lamontagne]

The original intention was that the male hemispherical end would fit into a female hemispherical end.  Upon realizing that the center pivot really shouldn't take any weight, -'f any wear on thevsoider wheels would increase the center pivot load, we decided to through bore the female center pivot.  That means the shape of the end of the male pivot becomes irrelevant.

See ya
Jason

[Paul Uhland]

Jason...I'm assuming your statement is: "...AND any wear on THE SPIDER wheels would increase the center pivot load, we decided to through-bore the female center pivot "...makes the most sense to me.

[Bob Holmes]

Let me see if I've got this right:  it's a "spider sandwich" between upper and lower ring rails?

[Paul Crabb]

I see that the ring rails for the underside of the bridge have been bent. Have the lower ring rails also been bent? Were the ring rails bent on site or sent out and bent? Just wondering given our unsuccessful efforts to bend the lower ring rails last weekend.
Paul C.

[Mike Fox]

"The Bender".. You bend over to pick it up by yourself, and you stay that way. Heavy..

[Ira Schreiber]

Aldon Rail Bender. Manually operated and a back breaker. I have bent many rails with one of these over the years. Bigger models are hydraulically operated. Still a back breaker but much less turning of the screw by hand.

[Paul Uhland]

Branford has  a hydraulic one.
Make them a deal.  

[Benjamin Campbell]

Is that the rail bender with the brazed repair? If so – I donated it when I first joined the museum back in the 90s and was fearful that it would not hold up under actual use. I am impressed that the repair has held and that such a perfect arc could be bent with that type of tool. I assumed that we would have to have the ring rails bent/rolled at a structural steel shop.

[Stewart "Start" Rhine]

The key to uniform bending is to measure/mark exact increments on the rail and apply equal amounts of pressure at each increment.  This is done by running the bender screw against the rail hand tight at the center line of each mark and then turning the screw five times with the same amount of travel to the bar. 

[Pete "Cosmo" Barrington]

But...I thought it was ... EIGHT_to_the_bar! 
*ducks and runs*

[Paul Uhland]

Musical or not, looks like it woiks fine to me.
Will rail segments be welded in to complete the coicles?
Hope da crane comes soon. 

[Jason M Lamontagne]

We intend to apply bent joint bars at the 3 joints in each ring.  The crane, the services of which are being donated, is scheduled for early next week.

See ya
Jason

[Chuck Watford]

Great work!  Any photos of the spider and wheel assembly yet?