Home made Dobsonian Base.

[scogyrd]

ha ha

cheers mate - I did mention somewhere that my mount was inspired by you and OOUK of course

good luck with your own build!

I don't know how I missed that bit.

Your mount does look good though, it looks a lot neater than mine.

[Astrokev]

quite positive and actively applying for jobs etc - want a new career so in seek and justify all my skills mode currently. got a decent package though so have some time and it may even work out well. my wife has a good job too and I think will be the main breadwinner for a long time to come!

you're a genius mate with the LP. I do actually have some still in the loft so bonus!!

this will enable me to get it finished while Russ and I work on a joint purchase of some laminate/formica.

Good luck with the career change! I'm in the same boat, actively applying for new "opportunities" and hoping for the best. Living off my package so don't really want to blow any of it on the long list of projects I've got lined up....just in case! Well, not yet anyway!

Edited June 9, 2011 by Astrokev

[Moonshane]

same here mate so thanks for the tip! and here it is - 12" version of 'Good Life' by Inner City - not seen the light of day for about 20 years!

[Moonshane]

I don't know how I missed that bit.

Your mount does look good though, it looks a lot neater than mine.

he he no probs mate. hey if it works, it works. the best thing with this one is has cost me the grand total of £2 at the current time as I already had the wood in the shed.

[Telrad]

I thought to myself, I wonder...........and as an added bonus (and this was pure luck) the scope sits nicely within the base with the alt bearings attached, making for a quite compact and neat package - allowing it to be carried in and out in one. nice.

Very neat and tidy solution. So much better and safer than carrying dobs individually. I always think that one day, it'll slip in my hands when I carry the OTA on mine But with your dob mount, it looks secure and definitely makes it's easier to 'lug' around. Seriously think that you should submit this design to some manafacturers, and get them to re-design their dob base. It would certainly make it better to carry with the handle/cut-out! You're a genius dude.

[spaceboy]

Sorry to hear about the redundancy Shane. I have been out of work for a while now but like you my wife has a good job with a good company so in the end we decided it would be best if I looked after the kids. I won't lie I'd much rather be back in work, for one it would be easier than having to look after two energetic children all day . I'm sure you and Kevin will find some thing soon.

[swamp thing]

this will enable me to get it finished while Russ and I work on a joint purchase of some laminate/formica.

Don't buy formica Shane have a word with a local kitchen fitter and grab one his sink or hob cutouts.

They've only got to pay to dump em otherwise.

Regards Steve

[Beulah]

Shane,

Excellent work, you are very handy with the tools.

I am beginning to wonder whether to make a base like this for my dob, I am getting hacked off with the footprint of the circular base...

Edited June 9, 2011 by Beulah

[Astrokev]

same here mate so thanks for the tip! and here it is - 12" version of 'Good Life' by Inner City - not seen the light of day for about 20 years!

Excellent choice!

[Astrokev]

Sorry to hear about the redundancy Shane. I have been out of work for a while now but like you my wife has a good job with a good company so in the end we decided it would be best if I looked after the kids. I won't lie I'd much rather be back in work, for one it would be easier than having to look after two energetic children all day . I'm sure you and Kevin will find some thing soon.

Cheers Spaceboy. Much appreciated. Meanwhile, I continue to plan, draw ideas, research, plan, dream.....

[Moonshane]

Very neat and tidy solution. So much better and safer than carrying dobs individually. I always think that one day, it'll slip in my hands when I carry the OTA on mine But with your dob mount, it looks secure and definitely makes it's easier to 'lug' around. Seriously think that you should submit this design to some manafacturers, and get them to re-design their dob base. It would certainly make it better to carry with the handle/cut-out! You're a genius dude.

ha ha wouldn't go as far as genius but yes, I'm close

your comments have actually made me think of an addition I will make tomorrow - some finger sized cut-outs in the alt discs. this will make it much easier to pick up the OTA. I am sure you'll be fine carrying the dob - main this to worry about is things under the feet I suppose.

Sorry to hear about the redundancy Shane. I have been out of work for a while now but like you my wife has a good job with a good company so in the end we decided it would be best if I looked after the kids. I won't lie I'd much rather be back in work, for one it would be easier than having to look after two energetic children all day . I'm sure you and Kevin will find some thing soon.

cheers matey. mine are too old at 16 and 13 so no chance of that. applied for a few so will wait and see.....

Don't buy formica Shane have a word with a local kitchen fitter and grab one his sink or hob cutouts.

They've only got to pay to dump em otherwise.

Regards Steve

cheers Steve, good suggestion but I'm not a fan of the weight or the materials in worktops and much prefer ply. BUT as you say, a ready made solution!

Shane,

Excellent work, you are very handy with the tools.

I am beginning to wonder whether to make a base like this for my dob, I am getting hacked off with the footprint of the circular base...

it's highly recommended. if I'd have been making a 12" scope base, I bet it would have only been a couple of inches wider, maybe less.

definitely easier to move about and less storage taken up too.

Excellent choice!

cheers Kev!

[Moonshane]

quick update. added teflon pads, tacked and driven below surface - didn't have 'etched' teflon so glue no use. rounded off the sharp corners to aid smooth rotation. will see how the record/teflon effect works in the morning. obviously the pads are attached directly over the feet to ensure the weight is transferred to the ground directly. makes for a more solid mounting.

glued on the record to the bottom of the rocker and went round to father in law's (he has a pillar drill) to sort out the alt bearing holes.

will put up more pics of the finished thing tomorrow. will just need painting (by Steve!).

[Astrokev]

I've not searched yet, so may be readily available, but where did you get your teflon?

[rabbithutch]

Howdy, Shane!

Great design and great execution on the dob mount!

Any chance we could get dimensions?

[Moonshane]

I've not searched yet, so may be readily available, but where did you get your teflon?

hi Kevin

I generally get mine from Ebay - just search Teflon sheet

the one I used for this was 3mm thick and Kriege and Berry suggests 1.5x1.5 inches square for smaller dobs.

I think you can get 'etched' teflon too (and I'll be buying this next time) and this is better as it will take a good quality epoxy from what I read.

[Moonshane]

Howdy, Shane!

Great design and great execution on the dob mount!

Any chance we could get dimensions?

cheers Bob

To some extent the measurements are academic as they need to be designed to suit the tube for which you are making the base, the position of the balance point / length of the tube and of course observer height.

My main concern is always stability and I feel anything less than 12" at the base is basically unstable. It's broadly in 18mm ply. quality of ply is not essential if you are painting but if you are staining/varnishing then you'll want better 'furniture' quality timber.

the design is literally :

groundboard

a circle with feet set at 120 degrees and as far out as possible. this could be any shape really but a circle remains hidden at all times. e.g. a square would have corners sticking out when the rocker is turned. (toes, dark etc). teflon pads on the upperside 1.5"x1.5"x3mm fixed above the feet. mine is 13" diameter.

Rocker

basically four rectangles and a square base. square piece at the bottom to match the groundboard plus maybe 1/2".

sides need a circular section cut to match the bearings attached to the tube. needs to have a large enough curve to be able to fix teflon pads at 70 degree points from centre of arc. as mentioned match the height to the observer's height. I literally got him to hold the scope up to his eye while seated at about the mid point and measured to the ground.

front piece should be measured to reach as high as possible but to allow the scope to drop down to a few degrees.

back piece high enough to provide support and low enough to let the primary end of the mirror pass plus a few inches for balancing if required.

alt bearings

just circular sections maybe 1.5-2x the diameter of the tube. they can be half circles too. obviously need to be matched to the circular sections on the sides of the rocker.

hope this makes sense. really, like an equatorial platform, you need to match the dimensions to suit your own circumstances - one of the main advantages of making one yourself and the reason why I suppose, manufacturers use more 'generic' dimensions?

Edited June 10, 2011 by Moonshane

[Astrokev]

Shane

An interesting design point you mention above regarding the circular cut-outs on the rocker box.

Since the alt bearings only touch the rocker box teflon pads at 2 points, is there any reason why the cut-outs couldn't be simple right-angled "V" cut-outs. Although circular cut-outs do look more pleasing to the eye, from a functional viewpoint I guess they don't have to be. The teflon pads would need to be placed at the points of contact (which with a right-angled "V" would be 90' apart). Does this make sense and would you agree?

Years ago, I made a dob in this way, and it worked fine.

[Moonshane]

hi Kevin, yes, I totally agree.

as long as the teflon pads are at about 70 (not 90) degrees apart (imagine a 70 degree piece of pie from the centre of the bearing radius) then the shape of the cut out at the top of the side bearing does not matter. effectively, be it on a curve or a V, it's in the same place. so the angle of the V would need to be 110 degrees to ensure they are 90 degrees to the alt bearing surface.

Scogyrd did this on his thread but not sure what his angles were.

I have to say the LP and teflon combo is beautifully smooth. no stiction and perfect 'stoption' too. it moves when you want and stops where you put it.

I have found some contiboard end tape in the shed (the iron on stuff) and this will work well with the teflon pads for the alt bearings. will iron this on shortly and then show some pics of the whole thing. even with no teflon it slides beautifully in the saddle.

the whole thing is rock solid and I'll be making another one for my 6" f11 in due course.

wow, you CAN make anything out of plywood.

I am even thinking about making an alt az mount for a refractor and a car.

[Telrad]

Shane, I like the teflon pads. Smart idea, nothing less from a dab hand as yourself

I might try to make a base, but I fear mine would look like some sort of prototype as opposed to anything worth putting my scope on.

I have thought about making an eyepiece tray though to attach to my current base.

Nice One Shane !

Edited June 10, 2011 by Telrad

[Moonshane]

cheers matey.

the way I look at it is this. if you can get the materials for maybe £20 for the average base - OK maybe £30 you can have a go and if it goes in the skip afterwards at least you've tried.

you can get the wood all cut to size at the place you buy it from for either nothing or a few quid too.

none of the measurements are critical really, just that they need to be the same - eg the sides need to be the same size and shape, the sides need to be as wide as the base, the groundboard which is hidden need be no particular shape. you can use straight V cuts as mentioned by Kevin for the top of the sides. you could even rough cut a circle with a standard hand saw and then if you have a drill or grinder, use this as a 'lathe and sand the circle into shape, cut it in half and you have your bearings.

there's always a number of ways to do things and this was a great learning experience for me and will be useful when it comes to making the other two scopes I have planned.

I have just completely finished it and it works superbly.

easy to balance (the rings are a real help there) and lovely action.

I'll post some final pics later on as I need to tidy up now before my wife gets home and we go for some lunch!

Edited June 10, 2011 by Moonshane

[Telrad]

Shane, I can't wait to see the final pics. I am looking forward to it. As I say, I am inspired, and will definitely try to build one too now. I think it's great and you've designed and built it superbly. I'll have to pop down Homebase now and get some tools like you suggest, lathe etc. Cheers Shane! (enjoy lunch dude!)

Edited June 10, 2011 by Telrad

[Moonshane]

ha ha

have a go matey. seriously, all you need is care, a hand saw and a drill and I am sure you could make one.

an angle grinder would be good as a wood turning lathe to smooth the circle for the bearings with sandpaper. I bet if you have a woodworking shop nearby, they'd cut you a circle for not much cost. the alt bearings are really the only critical part.

[scogyrd]

One tool I would recommend buying when building the base is a sash clamp, or two. They're not really needed, my previous two bases were made without them, but they do make constructing the box part of the base so much easier. They don't have to be expensive either, mine cost about £8 each.

Buy Axminster Aluminium Sash Cramps from Axminster, fast delivery for the UK

I hadn't thought about using a drill as a lathe either. It's not a bad idea really. I'll have to try it when I get round to sanding my side bearings.

I'm sorry to read about you all being made redundant too. I've been unemployed for the last few months so I know how you all must be feeling, although I was self employed so I didn't get any redundancy pay.. In the long run it could be a good thing for us all though. I've been using the time to go back to college and gain some qualifications. I think the main thing to do is to try and keep yourself busy.

[Astrokev]

Mmm, interesting idea using a drill as a lathe. A couple of points spring to mind though -

1. Challange #1. Make sure the drill is well fixed to prevent any movement during working on the piece.

2. If the diameter of the piece being lathed is large, this is likely to put a huge strain on the drill motor at start-up due to the large inertia. (the drill is designed to turn relatively small diameter tools with low inertia).

3. Getting the piece to be completely square wrt the drill axis of rotation is difficult, and becomes more so as diameter increases.

Not saying it's impossible, but I once tried to lathe circular plastic sheet material using a drill and all the above created challenges/difficulties.

Oh, and wear goggles !! I recall an incident at school woodwork class once where a schoolmate failed to attach the cherished wooden bowl he was making onto the lathe correctly. Next thing, the bowl was through the window and ended up 20 yards across the field. Not pretty.

Edited June 10, 2011 by Astrokev

[Gina]

I've used a drill for sanding small parts.