Fixing a 6" f10

michaellxv (Michael) · #1 31-08-2013, 01:11 PM

Today I picked up a 6" f10 newt on an EQ pipe mount. It was free from a deceased estate and is mostly intact.

Why would I want to do this when I have a 10" light bridge I have hardly used all year? I'm still trying to work that out

, I guess it will be a bit of fun and as I now have 3 telescopes I have a collection

.

There is actually 2 tubes of different lengths. One has a primary mirror and secondary holder but no mirror. The other has no primary but has a different secondary holder with mirror.

The mirrors looks to be in quite good condition. I tried a quick swap of the secondary but it doesn't line up with the focusser. Oh, what focusser you just slide the EP in the tube.

The pipe mount is surprisingly smooth and i've never had a EQ mount before, although if I can get the OTA working I would probably look at building a dob mount for it.

So first problem to look at is the secondary holder and mirror.

brian nordstrom (As avatar) · #2 01-09-2013, 11:03 AM

Cool Michael , some ones pride and joy from yester-year , good luck it looks to be all there , a nice focuser , like the ones that pop up here regularly in the classifieds will finish it nicely .

On the mount pipe fitting mounts work very well , nice and solid , here is my pipe mount and scope I made in NZ , its a 5 inch f/13 with a 3/4 inch secondary , a real planet buster as yours will be to , it looks like f8-9 ? .

Brian.

michaellxv (Michael) · #3 02-09-2013, 05:26 PM

On closer inspection I found the secondary arrangement that I swapped in has a small lens presumably from a barlow in the path. Not sure that I like this idea. Also I worked out that to align the seconndary it was just a matter of grabbing the tube it is in and turning. Unfortunately in the process one of the spider vanes gave way so I have a bit more work to do in this area.

I did manage to get a bit of a look through it and everything is basically ok so I will keep working on it.

Brian, that's a neat arrangement on your's for attaching the OTA to your mount. Does it work well and do you have any more info on the design?

michaellxv (Michael) · #4 13-09-2013, 10:06 PM

I have attached the secondary mirror to the original holder and spider re-installed this in the OTA. I finally got to check it out properly tonight between clouds looking at the moon. Everything looks to be in order despite the lack of focusser and having to hold the EP by hand in the right spot.

I started drawing up some plans for a Dob mount and due to the tube length it's going to be quite tall. With the plan as drawn I can get all the pieces out of a single 1200x900 sheet but i'm not sure if I will need to make the base (280x280) a bit larger for stability?

Saturnine (Jeff) · #5 13-09-2013, 11:07 PM

Hi Michael

Have been following your adventures with the 6" F10, hopefully it has an well figured mirror , if so it will be a fine planetary scope.
The 6" F8 dob that I have, made the base 400mm in diameter and it's rock solid in anything but the strongest breezes, the wider the base the more stability you'll have.
For a scope the length of yours I'd recommend a base of 300 / 350 mm minimum if you have the materials.
Good luck with the project, a man can't have "too" many projects.

Jeff

michaellxv (Michael) · #6 14-09-2013, 07:55 PM

After playing with my cut template I got the base up to 350x350 then when I went to get the sheet of ply I found that the only 18mm sheets they had were 1200x594

I would need 3 sheets this size with lots of waste.

They had 1200x1200x12 sheets for $20 so I went with that. The base is now 400x400. I currently have 2 pieces being glued together to make the base stronger. I will use the offcuts to strengthen other key areas.

I did all the cuts today and assembled a dry run. Now its in pieces again glueing bits together.

For the Az bearing I am going to try something a bit different. I picked up a stick on vinyl tile and a pack of stick on furniture slides. The Alt bearing will be a 100mm pvc pipe cap.

mental4astro (Alexander) · #7 15-09-2013, 02:29 AM

Hey Michael,

The rocker box being so tall, you might like to add a pair of buttress 'wings', one on each side. With the large base, these buttress supports will greatly increase the rigidity of the box. The ply you've used being 12mm, it will need some more suring up.

The buttresses will also help with the aesthetics, as the mount won't appear so stark & awkward.

Mental.

michaellxv (Michael) · #8 15-09-2013, 07:34 PM

Quote:

Originally Posted by mental4astro

Hey Michael,

The rocker box being so tall, you might like to add a pair of buttress 'wings', one on each side. With the large base, these buttress supports will greatly increase the rigidity of the box. The ply you've used being 12mm, it will need some more suring up.

The buttresses will also help with the aesthetics, as the mount won't appear so stark & awkward.

Mental.

I have a couple of strips 30mm wide that I was thinking of using as a buttress but not sure if they need to be bigger to do the job.

A bit more progress today, I cut the alt bearing and did a quick check that the scope does actually fit. As shown I can stand and see in the EP except when pointed straight up. Once it goes up on the base it will be a bit higher, I don't think i'll be putting big feet on this.

mental4astro (Alexander) · #9 15-09-2013, 07:54 PM

30mm strips might not be sufficient. The latest pics you've posted have the scope really tall, which means the mount will experience a fair bit of torsion as you push & pull the scope. Here's a suggestion - stores like Bunnings often have an "offcuts" section where they cut timber. You might be able to find a piece of ply that can do the job if what you have left over isn't sufficient. That the offcut stuff is thicker isn't a problem. A bit of sandpaper & elbow grease, you can round off the edges which will help disguise the thickness.

michaellxv (Michael) · #10 15-09-2013, 09:56 PM

Thanks Alex, i'll see what I can find. I might put the 30mm strips on the inside corners.