Hi Guys,
Just a quick few questions about making a barn door tracker, hoping someone can help me out here.
Refer to uploaded image/drawing.
Is the distance between the plates/arm on a barn door tracker critical?
Will a wide gap between the plates/arms have an affect on the distance from the center of the hinge pin to the tangent screw?
Will the wide gap affect the performance of the tracker?
Reason being, the hinges I want to use are Glass-fibre reinforced thermoplastic;axle in stainless steel, excellent quality, very sturdy hinges I can import through work, they have no or minimal play.
(see the black hinge in picture)
Cheers
This is my first post on Ice in space, l hope it works!
(Sorry if someone has already asked this question before, I couldn't find a thread in the forum about this)
Hi Russman, to IIS.
Nice starter project, be careful, you will fall into the black $$$ hole of astrophotography real fast !!
Nope, should not make a blind bit of difference. How are you intending to drive the arm ? I notice screwed rod (?) at the other end but a lack of further detail. I presume you got some measurement specifications from off the web to determine the correct distance from hinge to the screw mount point.
Welcome to IIS. I built one a couple of years ago, and as I understand it the distance from the hinge pin center and the bolt hole is the most critical measurement. I don't believe the gap you are talking about will make a difference but I could be wrong. I had a similar gap. Not from the hinge, but because I used a coach bolt as my drive bolt with the rounded head providing a smoother action against the other board, and that head propped up the boards so they never touched anyway.
I'm trying to save $$$ not spend lol I'll try not to get sucked into that black hole for as long as possible, I imagine it will eventually get me though!
FYI - I plan to manually track for the time being. I am making the arms out of Black machinable plastic (can be drilled and taped etc), its hard, light weight and rigid! I'm making swivel nuts for the top and bottom, for the drive screw to pivot & I have the correct measurements off the web, I'll share some progress photos as I am making it... I'll make sure that there is plenty of room to mount a motor later on...
I am going to mount a view finder scope 6x30 and possibly a compass and a metal plate for my magnetic protractor (I don't know if they necessary though, they are in the thinking about it basket at the moment).
That drawing was just a quick scribble in paint, purely for the forum question the detailed image is still inside my head.
Stay tuned to this thread if you want to follow my progress
Actually, this distance (between hinge and threaded bolt) is not important at all if you intend to control the motor speed by means of computer (or micro controller).
For a computer version, have a look here.
For microcontroller version you have to have some basic digital electronics skills..
... I plan to manually track for the time being. ...
Then this distance may be critical - you will want the driving gear to turn with 1rpm, to be able to easily synchronise it with mechanical clock (by watching the second arm).
The measurement between bolt and hinge is critical.
Using a single piano hinge is the best way (IMO) to guarantee minimal movement and accurate attachment.
I took the handle off a grinder to use on mine. The large turning circle made it much easier to judge the timing.
Then this distance may be critical - you will want the driving gear to turn with 1rpm, to be able to easily synchronise it with mechanical clock (by watching the second arm).
My digital electrical skills are nil, way beyond my area of expertise, I'll have to stick to the old manual 1RPM method and make sure I get that measurement right. I think I have a 2RPM motor floating around, I can easily gear that down. I've got one of the local engineers cutting my plastic to size as I type.
Might be able to start working on it when I get home from work!
If you have 2rpm motor, then your arm length should be 2x longer, or thread 1/2 pitch, compared to what is needed for 1rpm.
Thanks Bojan, I'll keep that in mind.
You wouldn't know the specs if I used M6 x 1.0mm pitch thread would you, that would save me allot of drilling and tapping, as I have got plenty of metric threaded bits and pieces lying around!
Thanks Bojan, I'll keep that in mind.
You wouldn't know the specs if I used M6 x 1.0mm pitch thread would you, that would save me allot of drilling and tapping, as I have got plenty of metric threaded bits and pieces lying around!
I attached here a small excel spreadsheet for such calculations..
For your case (1mm thread pitch and 1rpm) the required arm length (centre-to-centre) is 229.18mm.
I've started a new thread, in the correct DIY category, as I noticed earlier this is DIY Observatories. Check out my prototype which I have decided to build before I go drilling into my nice pieces of plastic. Link below. I wonder if anyone has used a spring like this before. Beats elastic bands! Click here to follow new thread and keep and follow my progress
You can ask the mods to move this thread where it belongs...
Yes, this is a good way to reduce/eliminate the backlash in the screw.. possibly in your case the weight of the camera would bee sufficient to do the trick, though.. .
to IIS.
for the warm welcome! 
