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Equipment Discussions >> ATM, Optics and DIY Forum

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4670645 - 07/02/11 07:51 PM Attachment (39 downloads)

I then proceeded to drilling and tapping the brass focuser screws. Brass is pretty hard to machine. Here's a shot just before securing all parts:

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4670648 - 07/02/11 07:54 PM Attachment (31 downloads)

The brass inserts were then attached into the handles with some Loctite 603 glue.

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4670651 - 07/02/11 07:55 PM

Too bad the screws were 1-2mm too short. I'll have to redo this chore. the result is rather nice though

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4670664 - 07/02/11 08:01 PM Attachment (38 downloads)

Then it was time to finally decide how to mate the steel base plate and the bottom of the rocker. I chose a simple solution with a threaded insert acting as a reference.

I drilled a 7.5mm hole in the middle of the rocker to accommodate a metric M6 threaded insert.

Then I carefully installed the threaded insert in that hole. Finally I drilled the insert to 6mm thread.


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neo
Carpal Tunnel
*****

Reged: 02/12/08

Loc: Iasi, Romania
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4671217 - 07/03/11 04:39 AM

Down the hat to you sir a superb craftsmanship with every step!
Attention to details is remarcable


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: neo]
      #4673953 - 07/04/11 05:49 PM

Thank you Alex

I did not have the time to finish my report over the weekend.

Friday night I fully assembled the scope for the first time, with the welded ground board. At 3AM the job was done, and I consider the telescope functional.

First Light was Fri night (technically speaking Sat morning), when I set up the scope so Chriske and Guy (the two ATMers without whom my scope project would not have flown) could have a look. We looked at M13, M11 (Wild Duck), M27, M57, M31/32/110. When I tried to frame the Veil nebula I had to give up because of the blue sky background

It's fun to live at 51N around this time of the year - observing time is rather short due to the lack of astronomical night during 10 weeks.

On Saturday I tuned the azimuth bearing by adding a stack of plastic overhead slide washers (0.4mm thickness in total) to the center support point.

To ease transport I'm considering to keep the steel ground board frame detachable from the rocker. However a regular wing nut protrudes too much so my primary cage hits into it. A regular nut or a custom made flat wingnut (threaded scrap steel) might do the job here.

I'm very happy with the end result

Tweaks needing still some work are the electronics and the filter wheel, as well as a collapsible eyepiece holder I drilled last Friday. And a new set of brass thumbscrews to keep the focuser in place as the ones I made were 2mm too short


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4683834 - 07/09/11 08:37 PM Attachment (27 downloads)

I bought a new set of brass bookshelf holders and was very positively surprised that those ones already came drilled and tapped with a M3 thread

All I had to do, is getting longer M3 bolts and insert them into the pre-tapped holes.


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4683842 - 07/09/11 08:41 PM Attachment (31 downloads)

Unfortunately I couldn't source 30mm long brass M3 threaded bolts, hence I got myself some regular zinc plated steel bolts. I cut off the countersunk head of the bolt with a cutting wheel mounted on a Dremel.

Attached photo also shows the filter wheel housing after I spray painted it black. Protruding from the focuser plate are the 4 brass thumb knobs. Eventually I'll glue the threaded end into the knobs so they can't get loose.


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4683847 - 07/09/11 08:43 PM

The bad news of the day is that I'll have to completely rethink the filter wheel. It's hard to keep in place, when in place it doesn't run smoothly, and the cogwheel now stalls.

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4814092 - 09/18/11 06:08 AM

Most of what is called "summer" is gone now, and I did not have the occasion yet to try out my scope under decent skies

What I want to address now, are the following items:

1. Reduce weight where possible

I'm thinking about trimming the rocker and cut some holes in the lateral boards holding the altitude trunnions.

2. Make the altitude trunnions fit inside the primary cage

That should definitely ease transport. One option is to have the altitude trunnions have a banana shape instead of a full (half) disk.

3. On-board electronics

I'm talking about the power connector to the primary cage for powering the fans. Today I have no idea where I should best place this connector.

In addition I'll add a fan speed regulator circuit, LED illumination inside the primary cage for facilitating setup and tear-down of the scope during a dark and cold night.

Finally, one day I'd like to add a heated green laser module in an edge of the primary cage for easy star hopping.

In the far future I'll add secondary mirror heating.

4. Improve the filter wheel

The current setup does not work. It looks like I will need to use a ball bearing to keep the filter wheel in place. Maybe other things I should do here as well, to make it work.

I'm open to all suggestions - I do not claim to be a veteran ATMer at all


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874002 - 10/22/11 09:33 AM Attachment (19 downloads)

Time for an update.

After having transported and used the scope a couple times (still not under decent skies though) I start to see where I could improve things.

First, the rocker is rather tall because of the 4 protruding bits at the ends of the altitude bearing. I decided to cut those 4 corners, leaving enough room for keeping the primary cage confined within the bounds of the rocker while still offering enough room for repositioning the PTFE (Teflon) pads.

As in other phases of woodworking I first roughly measured where the cut should go, then I marked the right position on a piece of masking tape. A manual hack saw has been used together with a wooden guide to make a straight cut. The end result was very satisfying.

Here's a shot with the 4 corners and the masking tape in place:


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874006 - 10/22/11 09:39 AM Attachment (15 downloads)

With the 4 corners removed:

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874011 - 10/22/11 09:43 AM Attachment (11 downloads)

Yesterday I drilled the hole for the XLR power connector in the side of the primary cage. I determined the location of the hole based on the available clearance (just below the lower baffle of the primary cage) and constrained the location of the hole to be drilled by the known size of a wood screw holding the primary cage together.

The dimensions were transferred on a bit of masking tape (as usual):


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874015 - 10/22/11 09:46 AM Attachment (15 downloads)

I had to remove the mirror cell for the job, and eventually it turned out that I was too close to a small screw so that one had to go as well for the job to be completed. That made the job rather long.

The hole has been drilled with a 20mm Forstner bit. To avoid tear-out I clamped some scrap wood to the back (I made sure the hole would go right in the middle of the wooden plank that keeps the lower baffle in place).


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874025 - 10/22/11 09:50 AM Attachment (13 downloads)

I sanded the hole after this.

In parallel I have been working with varnish as well. Every surface got at least 2 new coats of varnish, now that the cutting and drilling is over.

Here's a view of my improvised workshop:


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874032 - 10/22/11 09:52 AM Attachment (15 downloads)

The perforated disk resting on the hexagonal box is an eyepiece holder for the AT Voyager mount. It holds up to three 2 inch and nine 1.25 inch eyepieces.

Here's a view from the other side.


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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874035 - 10/22/11 09:54 AM Attachment (13 downloads)

A close-up of the drilled power connector hole in the primary cage. The hole received a generous coat of varnish, thanks to a 20mm diameter varnish roller which I could fit into the hole

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874049 - 10/22/11 10:02 AM Attachment (18 downloads)

Finally, yesterday night after a brief observing session under unfavorable yet typically Belgian fall conditions (very humid and cold, but still relatively starry), I couldn't detach my focuser anymore, since the custom bolts I made had their heads going off but the threaded rods remained in place. I had to resort to pliers for removing 2 threaded rods.

This reminded me to use Loctite 603 metal glue (this green stuff from a red bottle) to lock the heads onto the threaded inserts. That was yesterday's final job.

After that I re-cut the threads as some were damaged with the pliers earlier that night.

Here's the end result:


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square_peg
Postmaster
*****

Reged: 03/26/04

Loc: Maple Valley, WA
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874079 - 10/22/11 10:25 AM

Looking good, Olivier. I like how you make do with what you have and still get professional looking results.

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Olivier Biot
Amused
*****

Reged: 04/25/05

Loc: 51°N (Belgium)
Re: My very late 14 inch f/5 project... new [Re: Olivier Biot]
      #4874090 - 10/22/11 10:27 AM Attachment (20 downloads)

Here's a photo of the parts that I'm considering to use as an eyepiece holder for my scope.

The rectangular plank is a spare I cut for making the removable slanted back panels at the back of the primary cage.

Based on the dimensions of the eyepieces I have, I came up with the hole pattern in the wood.

The rounded triangles are the trimmed leftovers from the rocker. They'll serve as holders to keep the eyepiece holder board perpendicular to any vertical surface I'll mount it to.

What I have not yet decided, is where to mount it.


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