More tube surgery

[Dave_D]

So now i'm adding extras like electronic focusers and (fairly soon) the extra bulk of a cooled DSLR, the tube of my trusty orion optics GX250 just isn't up to the task of supporting this lot. I've already noticed slight flexure in the focuser area by applying lateral pressure to the crayford, and indeed, i could see the tube ever so slightly distort.

Enter a piece of 500mm x 250mm x 0.5mm galvnised steel sheet, discounted to the princely sum of £2.50 at B&Q. It's incredibly springy... i've bent it round to approximately the diameter of my ota and it returns to almost flat. Should provide the necessary strengthening to the focuser area of my ota.

Also going to be a good excuse to flock the tube once it's done 

Only downside is that i'll have to (once again) completely disassemble the ota so can someone please buy some incredibly expensive kit to ensure a few days of total cloud coverage 

[RichM63]

This should be interesting.

I'll order a new guide/finder scope if you think it will help.

[laser_jock99]

I did a tube strengthening mod on my 8" F4 Newt to allow heavy imaging kit to be fitted

http://stargazerslounge.com/topic/188542-diy-super-newt/?hl=%2Btube+%2Bstrengthening#entry1965191

The final result is a super stiff tube around the focuser. The other upgrades you need to consider if you haven't done so already are longer, stronger dovetail bar(s) preferably the Losmandy type. The other essential addition is a strong 'top bar' to connect the two tube rings and give the tube more longitudinal stability. 

Heavy duty, 500mm dovetail bar vs standard skywatcher bar.

10" F4 Newt with the longer, heavy duty dovetail bar and 'top bar' fitted. The wider spaced tube rings are less inclined to 'tube sag' and the 'top bar' ties in the free end of the tube rings.

[Dave_D]

The other upgrades you need to consider if you haven't done so already are longer, stronger dovetail bar(s) preferably the Losmandy type. The other essential addition is a strong 'top bar' to connect the two tube rings and give the tube more longitudinal stability. 

That'll have to wait until i have a mount that won't curl it's toes up because of the extra load... only got a vixen gp which is already groaning under the weight.

[faulksy]

done my vx 14 as well

thats the ring i made

fitted here then flocked

[Dave_D]

Whoever did it, thanks for the clouds  i don't feel as bad stripping my scope lol

Anyway, progress so far

time to drill and rivet the tube then onto flocking...

[Dave_D]

btw rust-oleum spray chalkboard paind is giving a very nice finish. just in case anyone needs to spray the inside of their ota

https://www.google.co.uk/shopping/product/7340631293896060112?q=rust-oleum+chalkboard+spray+paint&es_sm=122&bav=on.2,or.r_cp.r_qf.&bvm=bv.71198958,d.d2k,pv.xjs.s.en.jzbNoov7U2A.O&biw=1600&bih=775&tch=1&ech=1ψ=DprLU_SJJqTY0QWQ4IHoBw.1405852175596.3&ei=EJrLU5W9JOXA7AaZ_4DYBw&ved=0CFAQpiswAA

[Dave_D]

focuser drawtube is now no longer an 'orrible big lump of shiny aluminium

not too happy with the rivetting... going to move up to 5mm dia rivets to really clamp the tube to the strengthening plate. after i chastise the child for putting green ink everywhere 

[Dave_D]

scope is finally back in action. the reinforcing plate seems to be doing it's job and the mods to the focuser and addition of an electronic focuser are working well. managed to fire off a few subs in the general direction of ngc7000 but i still need to fine tune the collimation. pondering treating myself to a catseye...

only about 15 minutes worth of subs as i didn't finish the rebuild till almost 1am and then the messing around setting up, so was around 2am.

still getting the mysterious vertical spike on bright images but nowhere near as pronounced as before flocking, bearing in mind that my scope is set up about 10 feet from the house and had to keep the the toilet light on for sick child. must have forgot to enable deringing but y'know, no biggie just for a test.

[Dave_D]

so, i made a circular template the exact inside diameter of my ota to try to figure out why the primary was off-centre. after a royal comedy of errors and 3 hours measuring every dimension of my mirror cell with a digital vernier, plus two minutes banging my head against the wall, i found out that my mirror cell only centralises the primary in the tube in one position (not the position it was currently in) which was giving me issues with collimation, and the three arms that attach to the ota are slightly off 120 degrees... slow hand clap to orion optics. hope their new scopes are better. definitely need stronger springs though. tbh i'm not too happy with the cell, it's a but 'amateurish'.

[RichM63]

LOL Dave, it was off centre to account for the flex bend in the tube that you have now cured with the reinforcing plate.

Good to hear that you are progressing.