Mirror's arrived and now the fun starts

[justin138]

Hi Phil, that sure is looking good! Quick question, what are you going to use to cover the mirror when the scope is not in use?

I was thinking of utilising your design and thought of a sliding cover to stop things falling on the mirror. Any thoughts?

Justin

[geppetto]

Justin

A cover is the next job before the inevitable happens :shock:

It will be a square of MDF (with cutouts to fit around the truss poles) cut to rest on some wood blocks

at the front end of the bottom OTA box.

Will post a picture when its done

[geppetto]

Cover fitted to protect the mirror from stuff falling on it :shock:

Next job is a complete disassemble to glue the joints and then

the MDF can have a coat of primer (unless a clear sky gets in the way ).

[GordonCopestake]

Looks good Phil! Great job. I see you have a shroud too, good addition!

[geppetto]

Gordon

Yes, the shrouds temporary, in fact its a bin bag :oops:

Going to call in at Chesterfield market next week and will be looking for some

blackout type material to make a proper one that easily clips on/off.

It's a necessary addition with all my local street light pollution

Will also be flocking the OTA boxes as well....

[lunator]

Phil

Amazing progress.

If you want to use AM's idea of hockey pucks there is a store in North London called Skate Attack and it will be able to provide pucks at a reasonable cost.

Cheers

ian

[GordonCopestake]

Phil, did you spot this by the way?

http://www.astrobuysell.com/uk/propview.php?view=9066

[geppetto]

Gordon

Thanks for the heads up.

Sent him an email

[geppetto]

Just an update

Second hand 2" focuser on it's way for the QDD (thanks again Gordon for the heads up)

Ad placed for a 63mm elliptical flat but no luck as yet.

QDD base unit is glued and primed with matt black, final coat will be satin black.

After a few nights use, I decided to move the ALT bearing blocks 1.5" nearer to

the secondary as my 2" 26mm eyepiece was making it slightly nose heavy as was

my Nikon camera. Also the new focuser will be heavier than the plastic one in now.

Measured up for some blackout material for it's shroud.

Results so far show how much more I can see with this 12" mirror even though the coating

is poor.

The base works well, both axis quite smooth but a bit of "sticksion" to sort out on the AZ.

Next job is to replace the truss wood screws with 6mm nuts and bolts, do a final check and

then the OTA can have its base coat.

[GordonCopestake]

I should take commissions hehe

I look forward to seeing images of the final beast! You really should rename it, as it's no longer QD Dob, it's actually a HQ Dob!

[geppetto]

You really should rename it

Open to suggestions guys

(clean ones only of course :nono:)

[GordonCopestake]

How about "Philip's 12" MDF Dobsonian mounted Newtonian telescope" - The P12MDMNT, snappy!

[geppetto]

Lovely day today so got some stuff done.

Trusses are now bolted on and the ALT blocks have been moved

so I'm now getting perfect balance.

Re tapped the threads on the 4 ends of the spider to M4 thread

as I hadn't got any long enough screws of the original thread size.

Done some sanding down but the primer will have to wait till tomorrow

because the skies clear again 8)

Re collimated, dressed up the QDD in it's bin bag shroud and hoping to

have a look around later

[FLO]

Mr Dobson would be proud of you 8)

[lunator]

Top quality shroud

Great peice of ATMing Phil

[geppetto]

Took advantage of the nice weather to get the QDD

stripped down and painted with an aluminium based undercoat.

Final coat will be satin black 8)

[GordonCopestake]

So THATS how you re-aluminise a mirror!

[geppetto]

So THATS how you re-aluminise a mirror!

Brush marks can be a problem though Gordon

[GordonCopestake]

I thought thats were diffraction spikes came from?!?

[geppetto]

Secondhand R&P 2" focuser with 1.25" adapter arrived this morning for the QDD.

It's in very good condition and has a smooth motion, 1000% better than the plastic

one that's in now.

Will strip it and polish it all up and replace the sticky grease..

A bargain 8)

[geppetto]

Been doing a few scribbles to work out how the QDD's setting circles are going to be fitted.

The AZ will be similar to what I did on my Revelation DOB, a circle of thin ply (26" diameter for this scope)

fitted between the two base boards marked 0 to 360 degrees with a viewing hole and pointer on the upper base board.

The ALT idea is based on an inclinometer.

The ALT blocks will be through drilled in a pattern to reduce weight and to add a bit of style.

The block on the focuser side will have a 0 to 90 degree scale fitted and I will make a pendulum

which will freely swing from the ALT block center bolt and will indicate the elevation of the OTA.

The scale will have a bit of adjustment to do an initial set up of the OTA using a spirit level

Should work well me thinks 8)

[geppetto]

Bit further forward this morning.

Given the undercoat a sanding down ready for the satin black top coat.

Increased the size of the focuser hole to suit the new focuser.

Moved the mounting holes for the ALT blocks forward another inch

to compensate for the extra weight of the new focuser.

Through drilled a pattern on the ALT blocks to give it a bit of style 8)

Made and fitted (slide to adjust) the 90 degree ALT scale and the

pendulum indicator gizmo.

The pendulum is fastened to a piece of Teflon which slips nicely

around the ALT block centre bolt. The weight is a brass door knob

[Andrew*]

brilliant!

[GordonCopestake]

Looks good Phil, what scale is the disc? Do you get a good resolution?

[geppetto]

Do you get a good resolution

Gordon

The ALT blocks are 12.5" diameter, bigger than they look in that picture.

The ALT scale I've just measured and between each ten degree mark

is just over an inch.

Each degree covers one tenth of an inch on the scale.

Not bad at all