Barn door tracker

[gtis]

Hi

Is it possible to make a barn door tracker without the electronics

And put it in between a alt/az mount and tripod and will it work

Neil

[Steve Ward]

http://www.astropix.com/bgda/sample2/sample2.html

[steppenwolf]

Absolutely! Motorising these Barn Door (Scotch) mounts is a relatively new departure from the original design. In the original design, a disk and pointer are used to mimic the movement of a second hand on a nearby clock - it is all a matter of gearing and timing.

[ronin]

Initially they were just a screw thread such that one turn of the screw moved the "arm" the correct amount in angle for a 1 minute duration, about 1/4 of a degree (15/60).

The trick is getting the thread and the position matched up. The as said previously you rotated in accordance with the second hand on a watch.

Likely easier these days to use an allen head screw and an allen key.

Motorising them is a bit of a pain as getting a motor and gear box that rotates slow enough is not overly easy, as the final rate has to be 1 rpm.

P.S. Thanks for the link Steve, looks like something to do one cloudy nigh, which looks like it will be tonight.

[ChrisLX200]

Lots of designs now for a 3D printer (if you have access to one) - just search on Thingiverse for e.g.,

ChrisH

[Bizibilder]

The 1/4 x 20 bolt mentioned in the link is a US designation for a thread - for the UK you should find a 1/4 BSW bolt.  (1/4 inch diameter and 20 turns per inch thread pitch).  3/8 BSF is a possible substitute as it is also 20 tpi pitch - the diameter being irrelevant in this situation.

[happy-kat]

This website helps you with the maths of knowing for the threaded rod size you have bought how far away the hinge needs to be.

http://blarg.co.uk/astronomy/barn-door-tracker-calculator

For my design I used an m10 bolt this just meant my boards ended up being quite long and in hindsight a m6 or m8 would have been better.

I made one that does not need a tripod but will sit on a flat surface. I also chose a straight rod design, there are 4 main designs I chose the simplest to get going with.

http://stargazerslounge.com/topic/222131-my-barn-door-build/?fromsearch=1

I used it to capture comet Lovejoy. (I do have the parts to motorise it but it is still manual and if the weather ever gets a break I intend to use it again).

Have fun with you project.

[gtis]

Hi

Thanks can't i just make a wedge with two hinged pieces of wood and a threaded bar and set it to

My latitude and point it to Polaris and use the goto to rotate telescope

Neil

[happy-kat]

Your GoTo mount would need to support being put into EQ mode only.

Then if you have your mount on a wedge it would only track in RA axis and it should work.

You have a Nexstar I thought you could buy a wedge for those mounts?

A bit mroe reading and probably not to either.

Probably best to do some research on this to see what you mgiht be able to do.

[gtis]

Your GoTo mount would need to support being put into EQ mode only.

Then if you have your mount on a wedge it would only track in RA axis and it should work.

You have a Nexstar I thought you could buy a wedge for those mounts?

A bit mroe reading and probably not to either.

Probably best to do some research on this to see what you mgiht be able to do.

Hi

They make a wedge for the evolution but it's about £300

https://www.harrisontelescopes.co.uk/acatalog/Celestron-Wedge-for-NexStar-Evolution-and-SE6-8-93665.html

Neil

[eatabean]

I like to use a metronome app on my iphone (ProMetronome by EUM labs)  to time the turning of the screw. It talks to me in the dark, so I don't need to see a watch dial. Once I find the correct tempo for the beats, I can keep very accurate track of the stars. For you musically inclined out there, set the meter to 5/4, that will give you a "pling" on the first group of five second intervals... I like to set it to 15/4, and that gives me a "pling" every 15 seconds, close enough for hand turning. If you don't understand, ask.

[happy-kat]

That's an idea.

I sometimes use barn door clock my member Agnes it has built in tangent error correction though I don't turn it by hand long enough to make use of it I don't think.

 

Just checked the metronome is not compatible with my tablet.

[eatabean]

https://play.google.com/store/apps/details?id=com.eumlab.android.prometronome

Compatible with Android.

[happy-kat]

Yes found it on the Platstore, it is not compatible with my android device, probably my OS version is not compatible.