rack and pinion

[Bernard Rooney]

Hello I'm new here. My kids knocked over my boss's seben scope - about 150 ml I think - anyway the focusser was damaged and I need to replace it. It is a rack and pinion type (cheat ship plastic). Any ideas where to get a cheap one?

[Geoff45]

I doubt that you'll be able to buy one. Usually people buy focusers to upgrade their cheat ship ones, so shop's are only likely to stock something upmarket. You could try a few shops like Bintel to see if they have a discarded one lying around.

[bmitchell82]

also just be aware that some focuses house a lens that often come with cheat ship telescopes. if that is the case, your in for a world of hurt! :(

[Bernard Rooney]

Thanks for the replies.

Someone from Beecroft - that brings back memories. I lived at penno yupes ago. I'm near Nimbin now.

Seben got back to me and said I needed to take a pic of the focuser so they can price it. Here's a pic of the scope:

http://www.astroshop.eu/seben-telescope-n-150-1400-big-boss-eq-3/p,3997

In the meantime I've managed to glue the base of the focusser where it went through the tube, smashing itself into four pieces - the tube itself is now panel-beated back to a regularish shape. Mirrors and lenses still good. Just the rack on the rack and pinion focusser was damaged as the rack was plastic (why would a German company import Chinese and ruin the German good reputation for workmanship?) I've found a way to fix that too... so all good. The boss didn't take it as bad as I thought. Afterall I had to clean the whole scope including primary mirror as he left it uncovered on the verandah for months and pointing up. There were daddy long legs in there. Also fixed his spotting scope and the aforementioned rack was already partially damaged when i got it.

But wow, watching that thing hit the turf was one downer!

It only has a spherical mirror and I'm suggesting they get a parabolic mirror as I understand it improves focus - does it affect magnification and does the secondary mirror need replacing as well. Thanks if you got this far.

[torana68]

plastic (why would a German company import Chinese and ruin the German good reputation for workmanship?)

yes well, bit of a con as you would think German made would be ok but its actually nasty Chinese (as opposed to good chinese)

It only has a spherical mirror and I'm suggesting they get a parabolic

Id suggest binning it , doesnt sound like hes interested and it isnt worth much/anything anyway. It wont be any better with a new mirror as all the other bits are near rubbish, overall cost would be more than a good second hand 6" dob (which might actually work) :D
Roger

[Bernard Rooney]

I thought I could get this to replace the focuser. Its 31ml, but I'm not sure about length... how much does it matter anyway unless one is an ornithologist?


http://cgi.ebay.com.au/Meade-1-25-newtonian-telescope-eyepiece-focuser-70-/360282720179?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item53e28607b3

my original is the one on this scope:
http://www.astroshop.eu/seben-telesc...ss-eq-3/p,3997 (http://www.astroshop.eu/seben-telescope-n-150-1400-big-boss-eq-3/p,3997)

[bmitchell82]

good find, that could work for you. just measure the old focuser with the draw tube fully racked in from where the tube would be to the top of the racked in focuser, then ask the seller for the same measurement.

If they are approximately the same then your in like flynn a bit of fitting and you should be right as rain! good luck :thumbsup:

[Bernard Rooney]

Thanks. Like too many ebay sellers he doesn't respond. But I guess i can legthen what I need using the old inner tube and some plastic cement.

[torana68]

.....just clicked past 2 am where he is , Im guessing hes asleep :D

[Bernard Rooney]

My fault, he did respond. Seben wanted $72Aus for their cheat ship one! Thanks again. I borrowed his scope cause I sold my little 70 ml one and had withdrawal symptoms. I've contemplated buliding my own for a while - even making my own mirror - and can see this would be a great place to start.

Its so tantalizing out there. I'm in a great viewing spot here and just lying on my back and gazing remains unbeatable. So many thoughts go threw ya hed. What is beyond the universe? Probably more universes. What is beyond universes? What is BEYOND beyond universes. I don't see why it should ever stop. There are certainly no grounds for thinking so.... and its the same within us.

[Ian Robinson]

Here's one http://www.amazon.com/Orion-Basic-1-25-Rack-and-Pinion-Focuser/dp/B0000XMXF2
but it looks like it's cheap plastic junk .

If you can't find one, I think I have a nice all metal 1.25" rack and pinion focusor with a universial base that I bought for a project that never happened so it's never been used, which is stashed in the back of the filing cabinet somewhere.

[ZeroID]

Sounds like you still haven't scratched that itch properly. Won't go away will it ? I'm back after about 20 years and building a 10" Dob after getting hooked with a little 4'5" cheapie a few months ago. Now I've got the dreaded 'Aperture Fever' :eyepop: and need a remedy.
Forget about the bosses cheapo and scratch that itch, you know you need aperture ..

Clear skies !!

[GrahamL]

Sorry to hear of the trauma this scopes gone through Bernard.

A new focuser will not likely fix whats happened here in that should you of needed to reallign the optics with this scope fresh out of the box its a difficult proposition .. bouncing off the ground ?..is a huge ask
verging on impossible.

[Bernard Rooney]

Its all good now.