Tripod for my Dob...

[Chris Stacey]

As you've probably heard me moan about before, I dislike the base of my dob - the weight, awkwardness of it, ep height etc, all elements that annoy me. I can't afford an eq mount so I thought I'd build a mount myself. It operates exactly the same as the original base, i.e... rollers and tension handles. The tripod though is easier to manhandle, it folds up to just over a meter tall (which comes in handly if I want to take my dob anywhere - the dob fits perfectly into a snow boarding bag I acquired, which itself has thick padding, and the tripod, case of ep's, laptop etc all fit perfectly into a large Nike sports bag). The tripod is very sturdy, I modified an old PA speaker tripod I had laying about, it was originally build to house very heavy speakers so it'll easily perform for my intentions. The section the OTA sits on is rock solid, I could literally hang off of it with no movement at all. The laptop section can either move in parrallel to the scope so it never gets in the way, or I can loosen one handle and move the laptop section independantly, so I can have the laptop to the side of the scope etc.

As you can see there are a few more things to do, namely, the sections for the tension handles to go into. That will be two semi-circular pieces of beach wood (painted black obviously lol) the same diameter as the existing base so the handles fit straight in and operate to the same tension. Even without the tension handles the ota sits in at any angle I wish with no movement at all, but moves freely and easily when required - I completely surprised myself at getting those dimensions spot-on.

Another slight alteration that will be made is to lift the arms ever so slightly - when the OTA is horizontal it is about 3 - 4 degrees off the horizon, so i'll lower the bracket slightly, also I want to put a rotary angle encoder through the main shaft so I'll need to lower the bracket slightly so it doesn't interfere with the tube when it's horizontal.

Apart from that i'm just going to lag the legs and a little bit more tidying up.

Total build costs, about £25. Most of that was on 1.25" metal plumbing fittings and a can of black metal paint.

Oh yeah, the heater band you can see in the picture was one of my early mistake purchases, buying things I didn't need without realising, it works great as a counter weight to the dew shield though, hence I leave it on (Just wanted to point that out before someone mentions it )

[philsail1]

You've done a very professional job with there Chris! I take it it's still an "Alt Azimuth" set up, but on a tripod instead of flat base. Looks a more comfortable height than the Dob Base. I like the lap-top table!

As with any hobby - a lot of us tend to modify, and sometimes actually improve on the manufacturers original design!

The most important thing is, "if it works for you, then it must be better than the original!"

Regards,

philsail1

[Chris Stacey]

Thanks phil. Yeah it's still alt/az but on a tripod. Despite a few more bits to do to it I used it last night, it is so much more pleasurable to use. When pointed at the Zenith the ep is exactly at eye level - that in turn makes all other observing position far more comfortable. Previously when it was on the base I would get back ache within the hour and call it a day, I set it up about 22:30 last night and was using it until about 3am this morning - my longest session to-date.

Given that my DIY skills are normally akin to a limbless man I'm pretty pleased with how it turned out, it will increase my viewing sessions, so it's a win-win situation for me.

[Doc]

Thats a great set up you have made. I think making things for your scope is a great part of this hobby.

[Chris Stacey]

Cheers Doc. I agree, half the fun is in coming up with new ideas and then putting them into action.

The wife is delighted too, I'm in the shed most of the day.

[FLO]

That looks a good idea Chris, it also enables you to set it up on wet grass.

[Chris Stacey]

I hadn't thought of that Steve, that's another bonus.

[Doc]

Patent it Chris and get in mass produced

[Chris Stacey]

Don't go giving me ideas Doc, I'm likely to waste £200 on an application just to find out - See what you've done, I've already looked up the price. lol. In all seriousness though, it suits me and has made viewing easier and more enjoyable and that was the main intention.

Don't know why the links broken, I'll repair that. Just working on the tension handle holders and clips, plus a couple of other handy ideas I've had. I'll post a finished product in a few days.

[weareborg]

Hi chris

Any chance you could repair the links to your pics? I would love to see you design. Looking at doin something similar myself.

Andy

[Chris Stacey]

No probs, Andy.

I haven't got pictures of the finished tripod yet, for example, I've lowered the T-bar so the scope sits horizontal, the arms are much thicker and with two semi-circle sections above the rollers to put the tension handles into. The whole arm section looks much thicker and sturdier then the pics (I will put a finished one up soon).

Here's 2 of the original pics though:

[weareborg]

Thanks for that Chris.

That truely is a wonderful portable mount you've got there. Ive just had to get rid of my EQ5 mount and GOTO system to raise funds, but Ive kept my 8" OTA so that I can build a dob type mount for it. But after seeing your design, its certainly gotme thinkng. lol

Do you think that it could be motorised?? Before I purchased my Explorer 200 I was planning on building an 8" dob and motorising it using Mel Bartel's Scope Drive system, so I was wondering if it could be fitted to our tpe of mount.

Andy

[Chris Stacey]

Thanks for the compliment.

I don't know anything about Mel Bartel's Scope Drive system tbh, I'd have to have a look. If it could be motorised it's something I'd be interested in exploring myself. I can't afford an EQ5 or equivalant, I won't be able to until the current financial climate passes. I'll have a look at motorising and get back to you - vice versa, if you have any luck give me a shout.

I'll tell you one thing I learnt whilst experimenting with the T-bar, a standard bar with the arms directly attached pulls the scope over and makes it unstable (no matter how heavy you make the legs or laptop stand). To avoid it being over heavy I played around with hanging some weights directly off the arms in different T-bar configurations. The best method I found was to run the center pole through some 1x2 box section, then place your center bar through your cross-bar and above the box section. The arm section are in 3 sections, staggered in length, 3 inch, 6 inch and your final top section. All 3 sections are bolted togther with one large 10mm bolt. The arm sections are connected to the cross-bar and not the box section, the box section is long enough to support the weight of the corners where the arms meet the cross bar That method seemed to put most of the weight on the center bar and not make it top heavy. Even without a laptop opposite it feels sturdy and secure, well it worked for me anyway lol.