24.4" f/3.2 truss dobsonian project

[planetman83]

The width is 24mm, exactly like the width of the rocker sides. The grouping of 2 rollers also helps if I add goto for the use of steel wire rope to move between the rollers.

Edited April 8, 2021 by planetman83

[planetman83]

I received the second and final wood batch from the cnc cutting machine. I will now glue the groups of 2 pieces of wood. 15+12=27mm for the alt bearings and 12+12=24mm for the rocker up wood and sides. 

[faulksy]

29 minutes ago, planetman83 said:

I received the second and final wood batch from the cnc cutting machine. I will now glue the groups of 2 pieces of wood. 15+12=27mm for the alt bearings and 12+12=24mm for the rocker up wood and sides. 

looking good

[planetman83]

I was too busy all these days with the telescope. I am trying to make it as good as small as possible in every  dimension. The wheels with the bars inside so the width is minimum without getting in the way of the motion of the mirror box. and as low as possible. My goal now is the rocker + mirror box + the upper cage to be able to fit in my car. My car's trunk height is small (63cm), so it is a bit tricky. I have to do a few tweaks in order to make it happen.

Edited April 14, 2021 by planetman83

[mdstuart]

Fascinating. Interested in how your alt motion is with those bearings once it is all finished as I want to improve my alt motion.

Mark

[faulksy]

Brilliant mate. Looks ace

[planetman83]

Guys, what do you think? I managed to make it fit in my car. I have to make some improvements to the wheels so it can go up in the car easier.

[CedricTheBrave]

Epic

[saac]

7 hours ago, planetman83 said:

Guys, what do you think? I managed to make it fit in my car. I have to make some improvements to the wheels so it can go up in the car easier.

Lovely design, well done. I think I may steal some ideas from your design for the wheelbarrow arrangement - at the moment I have to lift this all and it's getting a bit heavy now  

Jim 

[mdstuart]

Looking forward to first light.

Excellent work.

[planetman83]

Guys, I am ready to test the telescope when the weather lets me. I forced to move the roller bearings to the back and the teflons to the front because the roller bearings jump when they go on the alt bearings gap.  I think the telescope is beautiful except of the small circles of wood putty of different colour you can see on the mirror box. This is not my job and I didn't know how to work the wood and what to do at each step.

 

Edited April 27, 2021 by planetman83

[faulksy]

1 hour ago, planetman83 said:

Guys, I am ready to test the telescope when the weather lets me. I forced to move the roller bearings to the back and the teflons to the front because the roller bearings jump when they go on the alt bearings gap.  I think the telescope is beautiful except of the small circles of wood putty of different colour you can see on the mirror box. This is not my job and I didn't know how to work the wood and what to do at each step.

 

That looks awesome. My classic dob originaly I used 2 wheels. Then I added a centre axle and put both wheels in the middle. Then only 1 ramp was needed

[mdstuart]

Looks amazing. How is the alt movement? How smooth, how much friction to start and then maintain movement etc?

Mark

[planetman83]

3 hours ago, faulksy said:

That looks awesome. My classic dob originaly I used 2 wheels. Then I added a centre axle and put both wheels in the middle. Then only 1 ramp was needed

Great idea! I will make the same modification.

 

2 hours ago, mdstuart said:

Looks amazing. How is the alt movement? How smooth, how much friction to start and then maintain movement etc?

Mark

I am going to test all these things today, if the weather lets me.

[planetman83]

17 hours ago, faulksy said:

That looks awesome. My classic dob originaly I used 2 wheels. Then I added a centre axle and put both wheels in the middle. Then only 1 ramp was needed

What is the weight of your telescope? Which wheels do you use? Can you upload a photo of the centre axle wheel system?

[faulksy]

1 hour ago, planetman83 said:

What is the weight of your telescope? Which wheels do you use? Can you upload a photo of the centre axle wheel system?

no problem. i will do it later

[planetman83]

I assembled and tested the telescope last night for the first time. The alt and az movements were good but a little bit stiffer than what I want. I will make some changes to this matter. The truss poles need to be cut at about 1cm as expected and planned to focus with everything, with the televue paracorr setting to A (if I use other settings, the poles need to be cut more but I don't want to cut them more than needed for now, what do you suggest about it? ) Regarding the balance, it needs about 2kg at the front (I had planned to need about 1.5kg in order to be able to add filter wheels or anything else at the upper cage later but I think I overdid it). I was also be afraid of being front heavy. I will add some counterweights at the upper truss poles.

I will also make a light shroud and a light baffle.

Edited April 28, 2021 by planetman83

[planetman83]

For the record, this was the previous telescope. (As I said before, I make a reconstruction of a used telescope). 

Before:

Total weight: 138kg

Unable to transfer it

 

After

Total weight: 84kg

Able to transfer (I hope)

[niallk]

20 hours ago, planetman83 said:

I assembled and tested the telescope last night for the first time. The alt and az movements were good but a little bit stiffer than what I want. I will make some changes to this matter. The truss poles need to be cut at about 1cm as expected and planned to focus with everything, with the televue paracorr setting to A (if I use other settings, the poles need to be cut more but I don't want to cut them more than needed for now, what do you suggest about it? ) Regarding the balance, it needs about 2kg at the front (I had planned to need about 1.5kg in order to be able to add filter wheels or anything else at the upper cage later but I think I overdid it). I was also be afraid of being front heavy. I will add some counterweights at the upper truss poles.

I will also make a light shroud and a light baffle.

Looks amazing- wow!! 👍👍👍

[planetman83]

On 27/04/2021 at 15:03, faulksy said:

That looks awesome. My classic dob originaly I used 2 wheels. Then I added a centre axle and put both wheels in the middle. Then only 1 ramp was needed

I already made the conversion.

[Michele Scotti]

23 hours ago, planetman83 said:

For the record, this was the previous telescope. (As I said before, I make a reconstruction of a used telescope). 

Before:

Total weight: 138kg

Unable to transfer it

 

After

Total weight: 84kg

Able to transfer (I hope)

Hi, as it seems you have a well built big aperture scope -btw congrats!- may I ask you to take a measurement of its natural frequency? It is one of the key aspect of the mechanical performance of a telescope and would definitely help me to benchmark our project.

I loosely described it here

you have a nice flat area over the focuser where it would be easy to clamp your phone and run AnaHerz - it takes 2min.

Kalispera!

Michele

Edited April 29, 2021 by Michele Scotti

[faulksy]

1 hour ago, planetman83 said:

I already made the conversion.

same as i did, but i have wheels almost touching just a washer between them

[planetman83]

18 hours ago, Michele Scotti said:

Hi, as it seems you have a well built big aperture scope -btw congrats!- may I ask you to take a measurement of its natural frequency? It is one of the key aspect of the mechanical performance of a telescope and would definitely help me to benchmark our project.

I loosely described it here

you have a nice flat area over the focuser where it would be easy to clamp your phone and run AnaHerz - it takes 2min.

Kalispera!

Michele

It works only with iphone? I don't own an iphone.

[Michele Scotti]

6 hours ago, planetman83 said:

It works only with iphone? I don't own an iphone.

Oh damn! Didn't consider that it's only on IOS. Thanks for looking into that anyway

[planetman83]

On 29/04/2021 at 20:29, faulksy said:

same as i did, but i have wheels almost touching just a washer between them

I left some space in order to be more stable. My ramp is 28cm wide.