10" dob, stepper motor for focus and movement - Page 2

asimov (John) · #21 16-08-2005, 10:05 PM

Good to finally put a face to the name Dave.

asimov (John) · #22 16-08-2005, 10:11 PM

BTW Apart from being addicted to this forum/astronomy/telescopes/collecting EPs I pull ANYTHING electrical apart just to get at the motor. I must have 30 odd motors kicking around by now.

davidpretorius · #23 16-08-2005, 10:23 PM

no worries asimov, well mount all assembled, stepper motor controller ordered tonight. Also talked to astronomy online and i am going to make one of these to attach the toucam to the 1.25" super duper series 500 eyepieces and also make to attach to the 2" ulltra wide. Simple idea!. It was going to cost $119 plus $85 for the extra bit for the 2" adapter. The toucam has a std thread for a tripod, so why not use so i can start to take shots at a wider view of say 50X, not the 200X i am getting in prime focus

http://www.astronomyonline.com.au/images/ph047m-0.jpg

asimov (John) · #24 16-08-2005, 10:30 PM

You don't muck about do you mate!? You certainly know how to throw yourself into a hobby.

iceman (Mike) · #25 17-08-2005, 06:45 AM

Those bearings on the base look nice - I wonder if they'll work on their own for hand-pushing the dob.. might be a good alternative to the teflon pads/magic sliders.

davidpretorius · #26 17-08-2005, 08:17 AM

bearings worked well last night, ie hand pushing. I have to extend the tube that aligns both base mount discs though, as with the extra height, it as sloppy if the nut wasn't done up, and it was a little tight if the nut was done up to keep the discs aligned, if you know wht i mean.

elusiver · #27 17-08-2005, 11:40 AM

from what i've read roller bearings are good for hand pushing but they have a tendancy to be too light.. and move with the wind. Simple way to counter this would be some sort of breaking mechanism. Or add something to give it abit more contact friction. With your centre bushing you could use a cut piece of a dynabolt housing.. i think that'd work.

Thiink · #28 17-08-2005, 11:47 AM

Hey David, let me know how you go with the afocal adapter. Theres an afocal adapter on my list of things todo and am keen to see how yours pans out.

davidpretorius · #29 17-08-2005, 12:12 PM

will keep you updated, looking good so far

Sausageman (Mike Boggan) · #30 17-08-2005, 02:48 PM

David,
I was talking to a mate yesterday about the sloppyness that would occur.
You will have to get a longer threaded bolt. You fit it from under the base upwards then run a nut down the bolt and tighten it. This will take out the slop and give you a solid point for rotation. The friction on the bearings can then be adjusted using the top nut, I haven't actually seen the arrangement on his dob, but it should work fine.

Mike

davidpretorius · #31 17-08-2005, 02:52 PM

thanks mike, will try tonight

ballaratdragons (Ken) · #32 17-08-2005, 02:59 PM

Dave,

what's next for the Dobbie? A coffee maker?

You are going to have to hire a Sea Container just to bring all that lot over for the Star Camp

Good to see DIY!!

davidpretorius · #33 17-08-2005, 06:08 PM

http://www.1-11.com.au/products/m_images/AL1450Open.jpg
we sell these jobbies at 1450mm wide. so my 1250 dob should fit in plus room for foam and accessories area. i am building up a tool kit, cordless drill, soldering iron, allen keys, wire, connectors, 12V battery all to fit inside! If we have any problem, then hopefully we can fix it at snake valley.

at the end of the day, i hope to be all kitted up.

at the end of the day, it is great to be an agent for engineering and hand tool companies. so many things get damaged in transit

I have a acclaim wagon, which I will be bringing over on the boat

davidpretorius · #34 20-08-2005, 08:25 PM

with the stepper, motors, i have read than you can micro step them by using different signals, but torque drops off exponentially. looks like gearing is the way to go. rs have gear reducers, but they are $168.

EL, have you bought one of these yet?

http://www.jaycar.com.au/products_up...oduct_3253.jpgfor $10 from jaycar?

Starkler (Geoff) · #35 20-08-2005, 09:49 PM

Quote:

Originally Posted by elusiver

from what i've read roller bearings are good for hand pushing but they have a tendancy to be too light.. and move with the wind. Simple way to counter this would be some sort of breaking mechanism. Or add something to give it abit more contact friction.

Some of the GS dobs came with roller bearings and some recommend a small piece of carpet or similar between the ground and top boards to create a bit of friction. You'll certainly need something so the scope doesnt 'roll downhill' or move in the wind.

elusiver · #36 20-08-2005, 10:54 PM

dave.. where's the base gonna go in the case

yep went to jaycar last night... got a couple of things. the gearbox is too small. but they have this geared generator type thingy that looks like it might be a goer.

el

davidpretorius · #37 21-08-2005, 08:26 AM

cool el, i have seen the gear kits you can buy, but not that keen to make up the box etc

let me know on the generator thingy, any pics or links on the internet

yup, base does not get to go in the case

cristian abarca · #38 21-08-2005, 04:05 PM

Hi guys regarding stepper motors ,in a previous thread someone said that printers have them. Which are better laser or ink jet printers?

Regards Cristian

davidpretorius · #39 21-08-2005, 04:09 PM

gee my guess off the top of my head would be inkjet because the ink tray has to be precisiely mved to where you are printing. but there could be some more stepper elsewhere in a printer???

i nabbed three (free) very nice 1.8 degree stepper motors out of old 5 1/4" disk drives

asimov (John) · #40 21-08-2005, 04:22 PM

I have a few steppers, precisely what do you guys need?