Where to find simple bearings for a tracking platform?

Phil Hart · #1 19-10-2009, 09:32 AM

I'm trying to build a simple tracking platform, which will actually be used as a slowly rotating base for night timelapse videos rather than long tracked exposures, but functionally they are very much the same.

I have a stepper motor and gearbox connected to a threaded rod. At the moment this directly drives a large wooden disc, but the axis tilts/flexes from the action of the threaded rod.

I tried the cheap Lazy Susan bearing here: http://www.smallparts.com.au/store/p...susan/all/1/3/

The flanges on that made it easy to attach things to, but there is still far too much loose play in that bearing.

So I am trying to find a simple precision bearing that is easy for me to attach to the tracking platform base and the driven wooden disc. Any ideas?

thanks
Phil

Phil Hart · #2 19-10-2009, 09:46 AM

Actually any suggestions for a whole worm/worm gear and easy to attach bearing combination would be great, as my wooden disc has lots of inherent problems too..

bojan · #3 19-10-2009, 11:30 AM

Try car wreckers. Or old washing machines..

Spanrz (Brett) · #4 19-10-2009, 12:58 PM

I have bought some parts (worm gear set) from small parts. Because I bought them in "surplus" mode, they were cheap, but I have to wait weeks for arrival..... They ran out (I suppose).
When they come in in the next couple of weeks, I'll let you know of the quality.

But Smallparts.com.au can be a pain to deal with, as they don't operate as a normal business (strange way of dealing).

See how it goes.

Rod · #5 19-10-2009, 01:17 PM

Hi Phil,

Not sure I completely understand what you are doing. Is this the same as an equatorial platform or are you just rotating the platform in azimuth?

I was going to suggest getting some nylon allthread rod and using it to create an epoxy gear on your wooden disk. JB weld is the best stuff I have used for this but some people I know have had good success with knead it. The epoxy gear can then be driven with another short piece of allthread (nylon or steel). I use 8mm allthread and the worm sits in 8mm roller bearings.

Come to think of it the azimuth drive on my scope might be similar to what you are thinking of. I can post a picture if you want.

Rod.

Phil Hart · #6 19-10-2009, 03:30 PM

This bit of kit started life as an equatorial platform (not very accurate) but I have flipped it over so the axis points to zenith rather than SCP and I am effectively just rotating in azimuth now.

Pictures would be great. What sort of bearing is your main gear wheel sitting in?

Phil Hart · #7 19-10-2009, 03:31 PM

definitely let me know how the small parts gears look. i was looking at their site earlier..

Spanrz (Brett) · #8 19-10-2009, 06:16 PM

Quote:

Originally Posted by philiphart

definitely let me know how the small parts gears look. i was looking at their site earlier..

This is what I bought (Below pic). This photo was a few months ago, as I asked for a photo of the gears before I even considered a purchase.

The problem is, their website (smallparts) is very cumbersome. The pictures are not really identifiable to the actual product, which is silly. The details are quite good, but the display/format of the pages are very busy.
Also, their way of business is a little weird. Smallparts can not be contacted other than email or online purchase, if you want to talk to someone, you have to talk to a subsiduary (hobby parts supplies - I think)...

I got a little peeved, when I did an online purchase, they charged my credit card within a day, then had the nerve to tell me a few days ( I think 4 days) after the purchase, "maybe weeks to get delivery as we have just sold out, do you want to wait?"
Wait??

I have already paid for them.

And I thought "surplus" meant that they still had stock?...Just.

360 toothed gear, I think it's about 150mm in diameter. This will be driven by the stepper motors. It's an experiment.
I just got frustrated in finding something good, this was it, but it's a case of waiting for it now. I ordered the gears on the 21 of Sept. One is supposed to have been supplied in 2 weeks, it hasn't, the other gear comes mid-late Nov....
They also put requested delivery at 30th of this month, so god only knows when I'll get them.

http://farm3.static.flickr.com/2443/...ea316f4c_b.jpg

Also, this is the Az bearing that comes with Bintel 12" Dob.
Something you are after?
2 thin bits of steel plate (maybe 1-2 mm thick) and a needle roller bearing.

http://farm4.static.flickr.com/3324/...4064498b_b.jpg

bojan · #9 19-10-2009, 06:36 PM

I believe the parts (or at least most of them) Small Parts are selling are actually coming from those guys in US:
http://www.sdp-si.com/Press/New/Belts2_5.htm

https://sdp-si.com/eStore/

Perhaps now that our $ is strong, this is the place to shop.
Also, here it is much easier to find your way...

Rod · #10 19-10-2009, 07:05 PM

Quote:

Originally Posted by philiphart

This bit of kit started life as an equatorial platform (not very accurate) but I have flipped it over so the axis points to zenith rather than SCP and I am effectively just rotating in azimuth now.

Pictures would be great. What sort of bearing is your main gear wheel sitting in?

Hi Phil,

My azimuth bearing is fixed and it is the worm that travels, attached to the aluminium rocker you see in the photo. A piece of 10 millimetre tubing is in the centre and acts as a pivot. The power cable is fed through this tube. A lovejoy coupling connects the allthread worm to the stepper motor.

Rod.

Phil Hart · #11 19-10-2009, 11:29 PM

Quote:

Originally Posted by Rod

Hi Phil,

My azimuth bearing is fixed and it is the worm that travels, attached to the aluminium rocker you see in the photo. A piece of 10 millimetre tubing is in the centre and acts as a pivot. The power cable is fed through this tube. A lovejoy coupling connects the allthread worm to the stepper motor.

Rod.

that's quite a contraption rod.. impressive. thanks..

Phil Hart · #12 19-10-2009, 11:35 PM

Quote:

Originally Posted by bojan

I believe the parts (or at least most of them) Small Parts are selling are actually coming from those guys in US:
http://www.sdp-si.com/Press/New/Belts2_5.htm

https://sdp-si.com/eStore/

Perhaps now that our $ is strong, this is the place to shop.
Also, here it is much easier to find your way...

thanks bojan.. that site is easier to navigate, but unfortanately i couldn't see the larger worm gears there and the smaller ones seem to be out of stock

Phil Hart · #13 19-10-2009, 11:38 PM

Quote:

Originally Posted by Spanrz

This is what I bought (Below pic). This photo was a few months ago, as I asked for a photo of the gears before I even considered a purchase.

360 toothed gear, I think it's about 150mm in diameter. This will be driven by the stepper motors. It's an experiment.

thanks Spanrz.. that worm and gear look great

i'd probably be happy with something half the size to keep weight down..

can you give a part number or direct link to that on the small parts website? i can't find anything that large, but there are a lot of sub-categories of worm gears with not much helpful information for plebs like me to find their way through them..

Spanrz (Brett) · #14 20-10-2009, 12:46 PM

Quote:

Originally Posted by philiphart

can you give a part number or direct link to that on the small parts website? i can't find anything that large, but there are a lot of sub-categories of worm gears with not much helpful information for plebs like me to find their way through them..

http://www.smallparts.com.au/store/p...hobby/all/1/3/

Yes, I did say it was very cumbersome to get around. Haha, easy to get lost there.

snowyskiesau · #15 20-10-2009, 02:34 PM

I've bought bearings from VXB in the US.
They have a large range and the prices are pretty good, especially with the $A at it's current rate.