200p dob mods

[knobby]

Having looked at it again, I think it will work either way but it will read 'minus' but thats ok, just need to get used to it !

edit - by the time i finish this it'll be goto

[stevetynant]

Brilliant thanks lenny. I've got a half size locking nut as well that would save me buying a new centre bolt. Hopefully catch up with you at the next meet.

[lennylovit]

no probs Steve , make new bolt if you like got s/steel thread bar as well

back to encoder, if you mount it above the center bolt faceing down that will turn it the other way so readout will run the other way

[knobby]

no probs Steve , make new bolt if you like got s/steel thread bar as well

back to encoder, if you mount it above the center bolt faceing down that will turn it the other way so readout will run the other way

tried that ... works but it reads as a minus no. works though ... still experimenting.

Aimed it at Aerial on a roof , zeroed it, spun it round a few times in variuos directions... pushed back to zero ... suspense builds ...

i'll tell you tomorrow

Naaaa it was smack bang on the aerial !

Not a scientific test, but a test , and it passed

[JamesF]

Looking at knobby's video I'd have thought that ideally you'd want the sensor spindle to turn anti-clockwise when the spindle is facing you as the dob turns clockwise relative to the base, or the base turns anti-clockwise relative to the mount. knobby's design achieves that by having the sensor spindle-up, I think. If you have the sensor spindle-down then I think you'd either need to drive it via a couple of 1:1 gears from the centre bolt, or have the sensor read backwards.

I may well have misinterpreted the video though.

James

[lennylovit]

i will look for another drive method in the morning ( gear wheel) and let you know got to be something on ebay (cheep)

[knobby]

You're both right, it turns the wrong way but it reads minus so its ok, just ignore the minus sign !

more pics and maybe a quick vid of it on the scope tomorrow

[JamesF]

Just been looking at the prices of plastic gears on ebay. Not at all cheap. I could get a couple of aluminium gears from motionco for the prices some of them are charging.

James

[stevetynant]

Thought about a gemred before I started the setting circle but for me it's one mod too far.you'll have three electric components going at the same timerunning and timing out in the cold.still interested to see how the mods go.good luck folks

[lennylovit]

Hi Knobby had a think bevel gears from motionco bevel gears GB1M016 £2.24 mounted like this

only need to open out the gears to fit encoder shaft and turn down your center bolt to fit gear

slotted holes to adjust to fit

[knobby]

I like that idea ...

Gave it a test last night, worked a treat, found M13, Andromeda, double cluster, all within the field of a 32mm EP.

Happy bunny

[lennylovit]

glad it woked for you keep us up to date

or like this

[JamesF]

Hi Knobby had a think bevel gears from motionco

I wondered about drilling and tapping one of the gears to match the thread of the pivot, then screwing it onto the pivot bolt the other way up and held in place with a locknut or a bit of loctite. The sensor box could then be fixed directly in contact with the base. The hub diameter seems to be 12mm though, which might be a bit small to drill out for a reasonable size pivot bolt?

James

[lennylovit]

get a longer bolt and turn it down to match gear

[JamesF]

Another job on the "justify the purchase of a lathe" list

James

[texaspete1973]

Wow Lenny,youve certainly started off at a fast pace with the modding! I'm liking what youve done so far and youve given me some good ideas, hope to see you at the next meet

[lennylovit]

out the shed today and made 4 center washers + 2 bushes for other s w v g members , be lost without my lathe ,love to make things

[lennylovit]

got your bit under way Pete , order a 12" lazy and we will help you fit it

[stevetynant]

I think we're coming to the end of dob modding, apart from go faster stripes on the ota I'm struggling to see where to go next. New scope next in a few years and start all over again.

[stargazer79]

My mods have been quite standard for a dob. The ota and focuser tube have been flocked, bobs knobs conversion on the primary and secondary mirrors, adjustable feet, 2d spirit level added to the base, second finder scope mounting plate has been added so I can use my rdf and finder scope. Just need to get my setting circle laminated and purchase a wixey

Sent from my GT-I9100 using Tapatalk 2

[texaspete1973]

I'll be ordering it very shortly,cheers Lenny

[knobby]

My mods have been quite standard for a dob. The ota and focuser tube have been flocked, bobs knobs conversion on the primary and secondary mirrors, adjustable feet, 2d spirit level added to the base, second finder scope mounting plate has been added so I can use my rdf and finder scope. Just need to get my setting circle laminated and purchase a wixey

Sent from my GT-I9100 using Tapatalk 2

Hi stargazer, does the flocking make much difference?

[Lenny147]

Yeah is flocking going to make that much difference? Isn't it more for imaging? I'm thinking of doing my 250px

[stevetynant]

Should hopefully increase contrast at the eye piece but yet to see the proof of that as yet. I think after a while even with better eye pieces your talking about small incremental improvements.

[Lenny147]

That's sort of what I thought, I may get round to doing it sometime in the future but for now it can wait