Sivakis,....I'm not surprised they don't know whats a T-nut! I tried and they all gave the same look...lol! Also imperial measurements aren't to many here. Most nuts are in Metric (M2, M3, M4...the number being the mm).
If you made the normal Barndoor with straight or curved bolt design with 2 pieces of wood and the hidge...then you could get 2 washers and a 1/4" nut and a 1/4" lock nut (the one with nylon inside). I secured my curved 1/4" threaded rod to the top wood plate this way.
- Rod-nut-washer-top plate-washer-lock nut.
At the bottom plate I used the black knobs which come with the Orion Tube Rings...they happen to have a 1/4" threaded cap which screwed onto the rod nicely. The rod then goes through the bottom plate with the black knob(threaded on) as a stopper. Turning the knob threads the rod up/down.
I have since changed the knob to a gear and about to go motorized. But at the same time...came up with another design...lol! Such is DIY when a new idea comes the others take a back seat! I will still stick with this as it's small and can be broken down to carry.
The new idea I have is more a tangent arm drive design which I need to refine more. I could easily get it fabricated outta aluminum, but the cost would justify buying ready made with a little top up...lol! Also loses the DIY aspect! The design isn't large but was looking into having EQ-like for wide field use which is a little more compact and without things sticking out all over...lol! Perhaps we could meet up and swap ideas....we may come up with something positive and permanent.
Anything feel free to PM me here. I need a ball head too...lol!
A momentuous occasion for me!
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timatworksg
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orly_andico
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Lol timatworksg, thanks for confirming that I'm not alone in this desperate search..... if it proves hard or near-impossible to find, I might have to look at more drastic measures - ie, force-driving the nut into the wood, locking it in there by sheer fit and see if that works... but if it doesn't, then I've wasted a perfectly good panel of wood.... I have enough to make another 4 panels, but I'd rather not...
Thanks for the suggestion orly_andico and an interesting one at that. 6mm bolts are a lot more common here than 1/4 but I'm wondering - if I change the bolt to 6mm from 1/4, would that affect the tracking if I follow the same 1rpm? Or would the 6mm require slightly more than 1rpm as compared to 1/4?
Thanks for the suggestion orly_andico and an interesting one at that. 6mm bolts are a lot more common here than 1/4 but I'm wondering - if I change the bolt to 6mm from 1/4, would that affect the tracking if I follow the same 1rpm? Or would the 6mm require slightly more than 1rpm as compared to 1/4?
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timatworksg
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- Location: Pasir Ris
I ended up with 1/4" rod as it was available at a Loyang Hardware store.
6mm requires a shorter distance from the center of the hinge to the rod position....as this shortens the diameter of the arc. 1/4" rod needs 29cm distance from hinge....the 6mm requires a shorter distance...which you can calculate:
====================================
Earths Rotation = 1436mins (23hrs 56mins)
Rods thread per inch = *example 1/4" diameter rod has 20 teeth per inch (you would have to check the 6mm rods TPI (thread per inch)
So the drive gear circumference needs to be : 1436/20 = 71.8"
Diameter of drive gear : circumference / pi : 71.8 / 3.14 = 22.855"
*22.855" !!!! Thats a whopping huge Gear!!
But you only need a small part of that 71.8" circumference gear (*Phew!)
71.8 / 24hrs = 2.99" (round off to 3" and lets triple that to 9" for the Rods length needed)
So all you need now is to Bend the Rod to match 22.855" diameter and cut off a 9" section that matches the curve the closest!
How far to put the rod from the Hinge center?
Diameter (22.855") / 2 = 11.43" (radius)
Measure from Hinge pivot bolt and along the wood 11.43" (29cm) and thats where you will place the curved/straight bolt.
So substitute accordingly for the Rod you need to use and count the TPI of that Rod. Calculate and you will get the distance needed.
=============================================
Yes 1RPM motors are hard to find. Unless you get a stepper, or like Orly, salvage from an old Floppy disk drive/Printer and buy/DIY a stepper motor controller with PWM (Pulse Width Modulation at the required voltage...normally 12V is best).
I made mine with a DC motor which pumps out 3RPM at 6V. I then found some 20 & 60 tooth gears to ration it down to 3:1. I happen to also have a PWM DC motor controller from Future Kit which I bought for something else (never happened due to other DIY ideas..lol)...hooked up so I have some adjustments if needed to speed up/slow down the DC motor. The PWM control pulses the motor to even give you 1RPM if needed but at the 6V rate...unlike a voltage speed regulator...that reduces power to slow a motor down...we need the boost of power but at a controlled rate...not reduced.
The parts were all salvaged....most from SIM LIM Tower..where else hehe! Gears were from Radio Control shops and I had to drill the centers to accept nuts and collars (battery drill helps).
What I hate the most is when you find the thing you really need....something needs to be modified to accept it...grrrrr! Hence why when I start one thing...along the way these mods make me re-think and it stalls the entire production...haha! Habit!
Lastly...for the wood...I just used good ole wood chopping boards...cut in half and to size. They are stiff, solid, whitstands water...and cheap (from IKEA..lol)
Hope that helps.....my design is stalled, plus going away with family 2moro for the weekend. Wish I had it ready....sigh*** But the break will probably bring more ideas...muahahaha!
Cheers
6mm requires a shorter distance from the center of the hinge to the rod position....as this shortens the diameter of the arc. 1/4" rod needs 29cm distance from hinge....the 6mm requires a shorter distance...which you can calculate:
====================================
Earths Rotation = 1436mins (23hrs 56mins)
Rods thread per inch = *example 1/4" diameter rod has 20 teeth per inch (you would have to check the 6mm rods TPI (thread per inch)
So the drive gear circumference needs to be : 1436/20 = 71.8"
Diameter of drive gear : circumference / pi : 71.8 / 3.14 = 22.855"
*22.855" !!!! Thats a whopping huge Gear!!
But you only need a small part of that 71.8" circumference gear (*Phew!)
71.8 / 24hrs = 2.99" (round off to 3" and lets triple that to 9" for the Rods length needed)
So all you need now is to Bend the Rod to match 22.855" diameter and cut off a 9" section that matches the curve the closest!
How far to put the rod from the Hinge center?
Diameter (22.855") / 2 = 11.43" (radius)
Measure from Hinge pivot bolt and along the wood 11.43" (29cm) and thats where you will place the curved/straight bolt.
So substitute accordingly for the Rod you need to use and count the TPI of that Rod. Calculate and you will get the distance needed.
=============================================
Yes 1RPM motors are hard to find. Unless you get a stepper, or like Orly, salvage from an old Floppy disk drive/Printer and buy/DIY a stepper motor controller with PWM (Pulse Width Modulation at the required voltage...normally 12V is best).
I made mine with a DC motor which pumps out 3RPM at 6V. I then found some 20 & 60 tooth gears to ration it down to 3:1. I happen to also have a PWM DC motor controller from Future Kit which I bought for something else (never happened due to other DIY ideas..lol)...hooked up so I have some adjustments if needed to speed up/slow down the DC motor. The PWM control pulses the motor to even give you 1RPM if needed but at the 6V rate...unlike a voltage speed regulator...that reduces power to slow a motor down...we need the boost of power but at a controlled rate...not reduced.
The parts were all salvaged....most from SIM LIM Tower..where else hehe! Gears were from Radio Control shops and I had to drill the centers to accept nuts and collars (battery drill helps).
What I hate the most is when you find the thing you really need....something needs to be modified to accept it...grrrrr! Hence why when I start one thing...along the way these mods make me re-think and it stalls the entire production...haha! Habit!
Lastly...for the wood...I just used good ole wood chopping boards...cut in half and to size. They are stiff, solid, whitstands water...and cheap (from IKEA..lol)
Hope that helps.....my design is stalled, plus going away with family 2moro for the weekend. Wish I had it ready....sigh*** But the break will probably bring more ideas...muahahaha!
Cheers
My wife never complained about how much time, effort & money I spent on my Astronomy hobby!................suddenly I met her!!!
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orly_andico
- Posts: 1616
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hi sivakis
you are right. a 1/4" bolt is 20 threads per inch or 1.27mm per thread. the M6 bolt is 1mm thread. So you'd have to:
1) turn it 27% faster
2) change the distance from the hinge to the screw 0.79X the distance (i.e. make it 8.97 inches instead of 11.4 inches).
again, getting a 1RPM motor is going to be tough.
there is an alternative -- get one of those cheapo EQ-1 type mounts and use that instead. They have eye-popping periodic error but would probably do. They can't be worse than a barndoor.
I made a barndoor years ago, even put a stepper motor drive on it. But it was $#@#$ unreliable and mechanically unsound. At the end of the day, a motorized EQ-1 type mount would probably be much less headache.
you are right. a 1/4" bolt is 20 threads per inch or 1.27mm per thread. the M6 bolt is 1mm thread. So you'd have to:
1) turn it 27% faster
2) change the distance from the hinge to the screw 0.79X the distance (i.e. make it 8.97 inches instead of 11.4 inches).
again, getting a 1RPM motor is going to be tough.
there is an alternative -- get one of those cheapo EQ-1 type mounts and use that instead. They have eye-popping periodic error but would probably do. They can't be worse than a barndoor.
I made a barndoor years ago, even put a stepper motor drive on it. But it was $#@#$ unreliable and mechanically unsound. At the end of the day, a motorized EQ-1 type mount would probably be much less headache.
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orly_andico
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- Joined: Sun Aug 09, 2009 11:14 pm
- Location: Braddell Heights
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Many thanks for the fast response and great advice!
Yeah, I've given up on the idea of a motorised version for now, at least until I can see my manual-version in practice before deciding.
Hmmm, so it IS possible to use M6 bolts - thanks orly for the distance calculation! This might make things a lot easier since the T-nut and bolts are readily available near my workplace.
All I need now is to get that tripod and ballhead (my Canon Tripod simply refuses to detach..............), small bit of drilling to secure everything together and I should be ready to go!
I'll take a photo of it once I'm all done
Yeah, I've given up on the idea of a motorised version for now, at least until I can see my manual-version in practice before deciding.
Hmmm, so it IS possible to use M6 bolts - thanks orly for the distance calculation! This might make things a lot easier since the T-nut and bolts are readily available near my workplace.
All I need now is to get that tripod and ballhead (my Canon Tripod simply refuses to detach..............), small bit of drilling to secure everything together and I should be ready to go!
I'll take a photo of it once I'm all done
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timatworksg
- Posts: 767
- Joined: Mon Feb 01, 2010 9:42 pm
- Location: Pasir Ris
@Orly
Yep...Sky Patrol....considered that really. Have been looking at the various small EQ type mounts meant for really small scopes and DSLR's! Sky Patrol is one...Sky Memo another and of course the Astrotrac...but the cost is always a deciding key factor. A case of basing my decision on 'do I pay a fair sum now....or DIY cheaper but prone to failures which would probably cost the same...lol!
Or maybe convert my Voyager to a small Sky Patrol clone?...hmmmm. So many ideas so little time....sigh!
Lastly,..saving up for a new CCD cam which is first in line on upgrades.
@Sivakis
The Barndoor project for me is a fun thing and I'm not concerned if it fails really. Its the fun in doing what could be possible with the limitations. Just the fix-it character in me...since a fair bit of my home reno was DIY to save cost. In the midst of some Steam Punk lights for my niece's Health Spa as decor. Need some brass plates to finish them off!
I have tons of spares, torn apart bits, lights, fixtures...all for DIY and mods which have an ending...which is just held off in many ways. Even a cooler for my Cam.
In the end...give it try if your having fun. It can cost when it comes to DIY but make a decision and go for it. If your like me...being handy...then I never did care..HAHA! Wife hates it though....gulp**
Yep...Sky Patrol....considered that really. Have been looking at the various small EQ type mounts meant for really small scopes and DSLR's! Sky Patrol is one...Sky Memo another and of course the Astrotrac...but the cost is always a deciding key factor. A case of basing my decision on 'do I pay a fair sum now....or DIY cheaper but prone to failures which would probably cost the same...lol!
Or maybe convert my Voyager to a small Sky Patrol clone?...hmmmm. So many ideas so little time....sigh!
Lastly,..saving up for a new CCD cam which is first in line on upgrades.
@Sivakis
The Barndoor project for me is a fun thing and I'm not concerned if it fails really. Its the fun in doing what could be possible with the limitations. Just the fix-it character in me...since a fair bit of my home reno was DIY to save cost. In the midst of some Steam Punk lights for my niece's Health Spa as decor. Need some brass plates to finish them off!
I have tons of spares, torn apart bits, lights, fixtures...all for DIY and mods which have an ending...which is just held off in many ways. Even a cooler for my Cam.
In the end...give it try if your having fun. It can cost when it comes to DIY but make a decision and go for it. If your like me...being handy...then I never did care..HAHA! Wife hates it though....gulp**
My wife never complained about how much time, effort & money I spent on my Astronomy hobby!................suddenly I met her!!!
Haha yeah, my wife does indulge me 
Like when i wired up my surround sound system - the living room wasn't exactly "visitor-ready" by the end of it
But yeah, DIY, for me, is the way to go! Like I said - refusing to spend $$ or finding ways to spend as little as possible makes it all the more fun, and rewarding
Like when i wired up my surround sound system - the living room wasn't exactly "visitor-ready" by the end of it
But yeah, DIY, for me, is the way to go! Like I said - refusing to spend $$ or finding ways to spend as little as possible makes it all the more fun, and rewarding
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orly_andico
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hmm. I have the same problem. I love to DIY, but the resulting monstrosities are most often unreliable or just plain don't work.
My wife always asks me why I insist on "saving money" with DIY, but the money ends up going down the toilet when my DIY fails. She doesn't understand that the process matters as much as (or even more than) the final result..
My wife always asks me why I insist on "saving money" with DIY, but the money ends up going down the toilet when my DIY fails. She doesn't understand that the process matters as much as (or even more than) the final result..