Hinge Tracker, the no wood barn door tracker

[ismangil]

I've started building Gary Seronik's hinge tracker project from Sky & Telescope magazine.

This picture is just how it will fit, it's not glued yet, and no way to properly turn the bolt.

It's basically a 200mm strap hinge, and the driver bolt is UNF 32 thread per inch.

-- Perry Ismangil

[barkis]

Interesting choice of hardware. Are you intending to drive the bolt with a motor, or manually? The pitch of the screw thread, and the distance the contact point is from the hinge itself (Polar Axis), determines the rotation speed required of the drive turning the bolt.

Good luck, it's a good project, so please keep us informed of your progress.

Ron.

[ismangil]

This version will be manual, and it has been calculated at 1 rpm.

The difficulty with motorizing this type is constraints by the simple hardware, it's hard to find cheap enough motor with the correct size gearing etc to get 1 rpm.

The original author based in the US managed to find 4 rpm DC motor with just the right size gears.

I can't find such motors here, without going into stepper motors etc.

-- Perry Ismangil

[gnach]

Greetings Ismangil,

How are you proceeding on the hinge tracker?

I found a link for cheap motors, referenced in another barndoor forum. The vendor is from Hong Kong that seems to offer these regularly.

ROBUST SMALL SYNCHRONOUS MOTOR AC 12V 1RPM CW/CCW fTr J91 | eBay

[ismangil]

Haven't continued this project as I'm busy with a telescope

I did get a motor from Hong Kong, a slow one, still need gears. The link you gave is AC, I wanted battery ones.

So components all there just needs to tie them all together.

[steelfixer]

Perry I have hundreds of plastic gears here from 8 teeth up to 80 teeth.

I rescued them from the local model shop when they were having a clear out.

If any sizes can help you out let me know and I will post them off to you.

[Moonshane]

can you not use a PWM controller? that's what I did with my eq mount.

[todd8137]

i was under the impression it was 20 threads per inch, mine was another design, is 32 threads per inch just for this strap hinge version ?

[ismangil]

Perry I have hundreds of plastic gears here from 8 teeth up to 80 teeth.

I rescued them from the local model shop when they were having a clear out.

If any sizes can help you out let me know and I will post them off to you.

Great, I'll figure out what I need and let you know!

[ismangil]

can you not use a PWM controller? that's what I did with my eq mount.

I intend to use that as well to tune the speed.

[ismangil]

i was under the impression it was 20 threads per inch, mine was another design, is 32 threads per inch just for this strap hinge version ?

yes due to distance from hinge to bolt this needs 32 tpi. Makes it nice 1rpm.