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Open Source Equatorial Mount

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#1 Adam Brunette

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Posted 17 January 2013 - 03:11 PM

Hello Everyone,

This is my first post, but I have been lurking on the forums for some time now. I getting back into astronomer, but have been interested in astronomy for many years.

Anyways, The reason im here is because I have begun designing an open source mount for those of us that like to take the do it yourself approach. I never seem to have enough money for my hobbies, so im always looking for ways to save. One being building a mount for a 12" SCT that I can use for astrophotography. I have alot of experiences with machine design so I thought it would be a good project.

The goal is a mount that can be machined 90% on just a lathe and most of the rest with a drill press. Using this as a guide, I think anybody with a lathe should be able to build one. Im shooting for a capacity of about 70lbs of equipment max or somewhere around there.

Here is a picture of what I have so far.
https://plus.google....977397423256...

Im looking for suggestions to make this as generic as possible. Currently, the mount is adjustable from 0 to 62 degrees. Im not sure if this is enough range, or even too much. Im at 42 so Im not worried about myself. Second thing im wondering about is what a common diameter for the counterweight shaft should be. Currently I designed it for 1-1/8" which is the same as the Losmandy counterweight shaft. Is this a good generic diameter or should it be different?

For some additional information: The large bearings on the RA and DEC are 6.3" diameter. The main tubes are machined from 4" diameter 1/2" wall aluminum round tube. The side supports are made from 5/8" plate aluminum and the base plate as well.

I think that's all I have for now. If Im out of my mind and there is no interest, please tell me. If there is interest, I will work with anybody interested to make the best low cost home built mount available.

-Adam

#2 stmguy

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Posted 17 January 2013 - 03:16 PM

I think that is a great project. On the Dec shaft dia , years ago I saw a mount at Stellafane that had a huge diameter Dec shaft which was very short, the reasoning being that that long Dec shafts can act as tuning forks and set up a harmonic which can be hard to track down..who knows ?

I say go for it

Norm

#3 fetoma

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Posted 17 January 2013 - 04:01 PM

Adam,

I am a machinist, and can give you some feedback if you are interested. One thing I recommend is not doing much on the drill press, but rather a milling machine like a Bridgeport. Give me a nice lathe and a Bridgeport with digital readout, and I could make just about anything. Problem is I have neither, nor access to them.

I believe that the capacity will much depend on the internal gears and bearing size. The bigger, the more capacity.

As for the counterweight shaft, I think the Losmandy size would be fine, but if you need something a bit beefier, you can go with the Casady size bar.

#4 hectar

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Posted 17 January 2013 - 05:09 PM

Adam I do have some CAD experience. your sketch does not shows much details. Could you post actual pictures and full cross sectional drawing with all of dimensions here?? Just curious, where are you located: Nigeria??

#5 Sean Cunneen

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Posted 17 January 2013 - 05:17 PM

From someone who has built a large mount, the challenges for me were how to drive the axis. Figuring out clutch arrangments for the RA and DEC that would hold and move nicely with a gearing assembly that was easy to make yet strong enough and precision enough for a large scope was very difficult. People who look at my project now have no idea how many renditions or drafts I've built to get to where it is now!

If you check out ATM vol 1, there is a section on mounts and what ingalls says holds true to this day, a telescope mount is only as good as the junctions between the dec axis and the tube as well as the RA and the dec axis. Those two junctions should be your focus. Everyone always gets hung up on the size of the bearings when in reality, mounts move so little bushings are often a better choice. If I could have machined bushings, I would have, but I had to go with bearings myself.

The other "rule" is to keep the counterweight shaft as short as possible and have the OTA as close to the RA shaft as possible.

I am envious of your Computer skills, I have to use "mind-cad"

#6 DaveJ

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Posted 17 January 2013 - 05:24 PM

...Second thing im wondering about is what a common diameter for the counterweight shaft should be. Currently I designed it for 1-1/8" which is the same as the Losmandy counterweight shaft. Is this a good generic diameter or should it be different?


I think you'd better check the specs on the diameter of the Losmandy counterweight shaft - it's larger than you mention - much closer to 1.25" than 1.125".

#7 Adam Brunette

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Posted 17 January 2013 - 05:52 PM

Adam,

I am a machinist, and can give you some feedback if you are interested. One thing I recommend is not doing much on the drill press, but rather a milling machine like a Bridgeport. Give me a nice lathe and a Bridgeport with digital readout, and I could make just about anything. Problem is I have neither, nor access to them.

I believe that the capacity will much depend on the internal gears and bearing size. The bigger, the more capacity.

As for the counterweight shaft, I think the Losmandy size would be fine, but if you need something a bit beefier, you can go with the Casady size bar.


The plan for the drill press was just for holes. I have a lathe and 2 come converted CNC mills, but I wanted to design something that somebody with a drill press and X-Y table and a lathe would be able to build.

The main end bearings are as big as I could get and still be economical. They are 6218-2RS which have a 160mm outside diameter which is about 6.3". The inside is 90mm. They are sealed and should never need greasing.

-Adam

#8 Adam Brunette

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Posted 17 January 2013 - 06:04 PM

Adam I do have some CAD experience. your sketch does not shows much details. Could you post actual pictures and full cross sectional drawing with all of dimensions here?? Just curious, where are you located: Nigeria??


I will get some more detailed pictures and cut-aways posted either tonight or tomorrow.

Im in Central Massachusetts in the USA.

-Adam

#9 orlyandico

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Posted 17 January 2013 - 06:38 PM

I found some neat ideas from looking at the Mach1. The polar fork is not a single-piece casting or anything but several machined billets that are bolted together.

the RA axis is simply a large tube that is bolted to another billet (that is then held in the polar fork).

the mount was obviously designed so that castings are not necessary. I'll try to post some photos of the internals when I get a chance.

#10 ccaissie

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Posted 18 January 2013 - 10:19 AM

Just curious, where are you located: Nigeria??

Charlton, MA is not very close to Nigeria, but some of us from Worcester used to think so. :roflmao:
For a project that is designed to be low cost and simple, I'm thinking this is quite sophisticated. I am familiar with the pillow block and plate designs when it comes to simple.

I agree that the broad brush concept is very nice. Details are what make it easy/difficult, and these issues come out in either prototype building or in detail CAD drawings that work out all the clearances, sizes etc. of components. As the details get worked out, please post. I'm interested in producing a nice GEM someday, as I consider a scope finished when I've star tested the optics, and I've got a lot of fine OTA's kicking around.

Love the open source concept. Sharing works.

go man, go!

#11 Startraffic

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Posted 18 January 2013 - 12:45 PM

Adam,
If you want beefy, & simplicity take a look at the Opticcraft mounts. http://www.opticcraft.com/ They use a lot of pillow block bearings & heavy shafts in their designs. The biggest machining issue looks to be the RA & DEC gears. I think they use Byers gears & thrust bearings for the drive mechanisms. I'm not a machinist by any means but their design seems simple, modular & solid.
I'm planning on a 8 or 9 for my 14.5" trailer scope.

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#12 ahopp

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Posted 18 January 2013 - 01:33 PM

Startraffic, I too have a mobile observatory, 8.5'x23'. Would love to see pictures of your setup and trade notes/experiences.

Tony

#13 hectar

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Posted 18 January 2013 - 01:33 PM

RE: ccaissie

I was just curious and I asked him because he didn't mentioned his location until it was asked in my post…(until 4th post)

To be honest, I had similar experience at another forum with a scam artist who had quite good knowledge of the astronomy and he asked me if I could help his sick sister studying at UK and send her some money. (and Nigeria had similar reputation).

Adam's project sounds nice AND If it is "open source" as he mentioned, he must have built it (he says so), lets share it here. Also if it is real, I would sure do my contribution but not by sending him money. Sorry Adam, I hope you are not one of the scam ??(My apology if I am wrong).


I am looking forward to hearing from Adam and knowing his machine design experience as well.
My next question: Is he willing to meet any of us from here and show the real project (and the progress)??

( I would warn everyone to be aware of SCAMS on any forums here at Cloudynights.com ).

#14 Adam Brunette

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Posted 18 January 2013 - 01:43 PM

From someone who has built a large mount, the challenges for me were how to drive the axis. Figuring out clutch arrangments for the RA and DEC that would hold and move nicely with a gearing assembly that was easy to make yet strong enough and precision enough for a large scope was very difficult. People who look at my project now have no idea how many renditions or drafts I've built to get to where it is now!

If you check out ATM vol 1, there is a section on mounts and what ingalls says holds true to this day, a telescope mount is only as good as the junctions between the dec axis and the tube as well as the RA and the dec axis. Those two junctions should be your focus. Everyone always gets hung up on the size of the bearings when in reality, mounts move so little bushings are often a better choice. If I could have machined bushings, I would have, but I had to go with bearings myself.

The other "rule" is to keep the counterweight shaft as short as possible and have the OTA as close to the RA shaft as possible.

I am envious of your Computer skills, I have to use "mind-cad"


Sean,

Thanks for the advice. Im going to find the information you mentioned now.
I chose bearings for a few reasons, One, as you mentioned is they dont need to be machined. Ebay is a good source for mechanical parts I have found over the years.

So you saying make sure the junctions between the the RA and DEC tube as rigid as possible. Im thinking of having the dovetail on the DEC machined right into the end so its as stiff as possible but thats down the road a little.

-Adam

#15 Adam Brunette

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Posted 18 January 2013 - 01:44 PM

...Second thing im wondering about is what a common diameter for the counterweight shaft should be. Currently I designed it for 1-1/8" which is the same as the Losmandy counterweight shaft. Is this a good generic diameter or should it be different?


I think you'd better check the specs on the diameter of the Losmandy counterweight shaft - it's larger than you mention - much closer to 1.25" than 1.125".


Dave,

You are correct, they are 1.25". I have corrected the drawing to reflect this. Thanks!

-Adam

#16 Adam Brunette

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Posted 18 January 2013 - 01:48 PM

I found some neat ideas from looking at the Mach1. The polar fork is not a single-piece casting or anything but several machined billets that are bolted together.

the RA axis is simply a large tube that is bolted to another billet (that is then held in the polar fork).

the mount was obviously designed so that castings are not necessary. I'll try to post some photos of the internals when I get a chance.


The Mach1 is a very nice mount. I was able to get some ideas from it. Like you mentioned, the DEC tube is mounted to the RA Axis.

I would LOVE to see the insides of one! Right now im stuck deciding on a clutch design.

-Adam

#17 Adam Brunette

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Posted 18 January 2013 - 02:18 PM

Just curious, where are you located: Nigeria??

Charlton, MA is not very close to Nigeria, but some of us from Worcester used to think so. :roflmao:
For a project that is designed to be low cost and simple, I'm thinking this is quite sophisticated. I am familiar with the pillow block and plate designs when it comes to simple.

I agree that the broad brush concept is very nice. Details are what make it easy/difficult, and these issues come out in either prototype building or in detail CAD drawings that work out all the clearances, sizes etc. of components. As the details get worked out, please post. I'm interested in producing a nice GEM someday, as I consider a scope finished when I've star tested the optics, and I've got a lot of fine OTA's kicking around.

Love the open source concept. Sharing works.

go man, go!


HA! A local! Well, What looks like use to be.

Im not sure it will be "Simple" but it will defiantly be as low as cost as possible and very sophisticated.

I use a program called Solidworks to do my designs in. It is a full 3D cad program that has fancy features like interference detection and structural analysis. I dont usually have issues with a design when I finally build it as Ive already found and designed them out in software.

My logic with this project is as follows: I have no want to manufacturer mounts. I simply don't have time. I do feel like others can benefit from my designs and some people will be able to build it if they want to.

Adam,
If you want beefy, & simplicity take a look at the Opticcraft mounts. http://www.opticcraft.com/ They use a lot of pillow block bearings & heavy shafts in their designs. The biggest machining issue looks to be the RA & DEC gears. I think they use Byers gears & thrust bearings for the drive mechanisms. I'm not a machinist by any means but their design seems simple, modular & solid.
I'm planning on a 8 or 9 for my 14.5" trailer scope.

Clear Dark Skies
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Startraffic,

I will take a look at what they make.

As of right now, the hardest part to make is the RA and DEC gears. They have to be super accurate. I have been looking into other options from my other machine design experiences, but I don't think I can come up with anything in the same cost range.

RE: ccaissie

I was just curious and I asked him because he didn't mentioned his location until it was asked in my post…(until 4th post)

To be honest, I had similar experience at another forum with a scam artist who had quite good knowledge of the astronomy and he asked me if I could help his sick sister studying at UK and send her some money. (and Nigeria had similar reputation).

Adam's project sounds nice AND If it is "open source" as he mentioned, he must have built it (he says so), lets share it here. Also if it is real, I would sure do my contribution but not by sending him money. Sorry Adam, I hope you are not one of the scam ??(My apology if I am wrong).


I am looking forward to hearing from Adam and knowing his machine design experience as well.
My next question: Is he willing to meet any of us from here and show the real project (and the progress)??

( I would warn everyone to be aware of SCAMS on any forums here at Cloudynights.com ).


ccaissie,

I understand your concern as I am a long time traveler of many different forums.

Since you post, I updated my profile to reflect my information.

To clear up a few little details though. The project will be released as Open Source when completed. (or sooner if somebody comes to me directly) I have no built the mount yet, as Im still in the design phase. I wanted to get opinions before I designed something people didn't like.

I dont take offense to your caution of scam potential. I would be cautious too if it happened to me.

Yes, I am willing to show the real thing to people when that time comes. Like I said, it is just in the computer right now. :grin:

And to finish up all these reply's, Here is some of the stuff I've built before.

Time lapse camera panner:
I designed this to hold very large cameras to do time lapse work. It is capable of rotating over 200lbs and can do so with 8400 steps of rotation per revolution. Unit runs from a 12V battery pack for cameras. http://www.flickr.co...57626111606853/

And a video:http://www.youtube.com/watch?v=iUJx6F_MnxA
And one of the milling machine I converted to CNC machining the top housing of the panner: http://www.youtube.c...h?v=UL8_wRSTzXs

And a shot of the little machine :http://www.flickr.com/photos/adambrunette/4737054165/in/set-72157624365713534/

I have done so many projects I cant list them all, But check out my you tube channel for a good overview including machine building, My golf cart, My electric Corvette, robotics and others. http://www.youtube.c...2b?feature=mhee

phew...done for now. I will post more pics of the GEM later.

-Adam

#18 hectar

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Posted 18 January 2013 - 06:14 PM

Adam you look quite resourceful and if it can be done, your name will be written in the history books of the astronomy just like Dr. Craig Stark who wrote world's best and free guiding program called PHD!!!

I would suggest following:

1. Declare it officially as an open source hardware project…
How/should this declared officially, so all of us here will be legally/morally bound to it? Could someone provide declaration/suggestions or more information about this?? We need help…
Btw I did find
http://www.youtube.c...h?v=9xGRaPrcvVg
By http://www.oshwa.org/
What every one thinks about this??
I personally think it is needed as there will be everyone's time and efforts involved. We must be honest and fair. We should honor what we say or declare.
(I would hate to see it stolen by the companies who are already making 300% or more profit, preying on people’s dreams and producing cheap/raw castings)

2. Come up with a plan. I.e. what are the sources of requirements for this project?? What is needed?. How it should be done etc..
I would say, we should start with a manual equatorial mount that will be capable of becoming an automated one. How strong, how much load, we will find out.

3. I am well aware what SW can do/ or what it’s capable of…We all will discuss what parts will be required and how they should work etc and then build them part by part. Then do the final assembly, run the simulation/FEA, which will point out itself where improvements/modifications are needed…

4. As we go along, you post videos and pictures of the progress here, at your YouTube channel and flicker account.

5. Once the design is complete/perfect, Most of us will manufacture it or get it manufacture at machine shop. Do the test and trials etc..

6. Next step will be to automate it and modify design for motors/controllers to run it and so on…(if needed)

7. Etc...Any suggestions??

PS: I am still awaiting dimensional drawing you were supposed to post here...

#19 skywolf856

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Posted 18 January 2013 - 07:51 PM

I think the Opticcraft mounts are the easiest design to duplicate with minimum machining capabilities required.

Here is my version with a 1 5/8" polar shaft and 1" dec shaft running in pillow blocks.

The clock drive is mine too! Designed using Stock Drive gearing products off the shelf using a Hurst 1 rpm syncro motor.

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#20 skywolf856

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Posted 18 January 2013 - 07:53 PM

Here is my homemade clock drive.

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#21 orlyandico

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Posted 19 January 2013 - 01:21 PM

you can get the gears from Aeroquest:

http://www.aeroquest...com/pricing.php

smaller one for the DEC. or, if goto is not necessary, use a tangent-arm DEC. it would be simpler, cheaper, and suffer less from backlash and stiction.

i would vote for a Raspberry Pi (or Chipkit32 Arduino) for the Goto controller, if Goto is desired.

the 10 Micron mounts use an embedded Linux SBC, not the cheesy low-RAM microcontrollers that are generally used in mounts.

#22 BoriSpider

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Posted 20 January 2013 - 11:25 AM

I should know a little about the OpenSource licensing since I
follow alot of OS projects, but I don't. Adam can join the G+
community "Makers, hackers, artists, engineers" community run
by adafruit.com and get the answers there.

I like this open source astro equipment trend. I have(just got)
a 3d printer. If the cad files are in a Blender friendly format
I can get them to my printer and print them to see how they fit together.
If the files can be exported to a '.stl' file, even better. If proto-typing in plastic will help I can be of
service.

#23 hectar

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Posted 20 January 2013 - 12:09 PM

I should know a little about the OpenSource licensing since I
follow alot of OS projects, but I don't. Adam can join the G+
community "Makers, hackers, artists, engineers" community run
by adafruit.com and get the answers there.

I like this open source astro equipment trend. I have(just got)
a 3d printer. If the cad files are in a Blender friendly format
I can get them to my printer and print them to see how they fit together.
If the files can be exported to a '.stl' file, even better. If proto-typing in plastic will help I can be of
service.


Me too!. "3d printer" which is kinda misleading term, is actullay a full manufacturing device; I dont have yet, but I am planning to get one. They are great for building proto-type parts.

#24 ccaissie

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Posted 20 January 2013 - 02:19 PM

A lot of nice looking work can be done using pipe fittings bored to suit bearing inserts etc. Clearly you want to get past the "sawmill" look on your mount.

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#25 Startraffic

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Posted 21 January 2013 - 07:21 AM

Tony,
I've actually got 2 trailers underway. One is a stock 16ft beavertail twin axle car trailer that I got for moving my tractor with. The other is a purpose built 9ftx16ft dual axle trailer for a 14.5f30 Shiefspeigler Bino obs. I just got the plans approved by MD Motor Vehicle Administration (after 4 yrs of design work!) & the construction/welding jig built. I haven't done much more than gather steel & axles yet. & I'm still guessing that the Opticcraft 8-9 will hold the scope. The scope & mirrors haven't been built yet.

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