Are there plans around somewhere?

Gavin,

Indeed! We plan on posting hardware plans - we're actually working out the kinks right now on a few designs we have implemented, and as soon as we get those worked out (a few more parts coming in the mail, one or two more things to be cut), we'll get the plans opened up and shared w/ everyone. I just don't want to encourage anyone to have the exact same problems we're having right now w/o a solution *grin*

I expect to start posting plans in the next week. The first will be for a pan/tilt unit capable of doing 0.0019' minimum movements, with 120:1 worm gearing, capable of moving 8+ lbs of kit, and using about 250-350mA of power for under $500. The idea for this design uses minimum custom parts (one slightly modified gear that the manufacturer will do the modifying on for not much, a custom shaft that one can make themselves, and acrylic panels cut-to-size and drilled properly) and if one has some basic shop tools (jigsaw, drill press, and dremel) can be made in a couple of weekends.

The second plans we'll release is for a dolly that will be capable of moving up to large-sized video cameras, can be made entirely out of off-the-shelf parts, and is extensible in sections for about $400-500. This one isn't going to look pretty, but will require a LOT less work than most of the DIY designs out there. I expect it to be a month before this comes out, as there're some timing issues on my end. Afterwards, we'll follow-up with what you see in the video (a fair amount of custom work on that), and then its successor, which we're prototyping right now - very little custom work, but more expensive than the dolly we'll be posting first.

We definitely will be using lots of 80/20 to show how to keep costs down and reduce any shop labor.

!c

Slau,

"Under $500." Not, exactly $500. Depending on the route one takes, could be way below $500, could be way above $500. Note I mentioned using worm-gearing, this will allow power to be cut, even to the tilt axis, between shots. Most of the stepper drivers that are inexpensive (the easydriver, or the pololu A4983) offer a sleep line that can easily be activated. While $500 may seem like a lot, other than cheap telescope mounts - purpose built timelapse pan and tilt rigs able to move 8+ lbs of gear start on the market at several times that price. Obviously, we can hit very low prices, but you're going to have to give something up somewhere. Weight (lighter payload), different gearing (change to planetary gearing, save about $10/axis, but have to keep power running the whole time). To examine some of the off-the-shelf options:

Mumford uses the time machine w/ two Sherline "enhanced" rotary tables: price: ~$3,025.00. Uses a lot more than 350mA of power.

Camblock starts at around $8,500.00 for a two-axis kit. I don't know about the power consumption.

The design is to provide similar capabilities to these systems, NOT an expensive way to do what a $200 Meade head will do. Note, the actual price one is likely to pay is around $200/axis, so yes, under $500. (Electronics would run about another $70.)

To answer some other questions:

1 Engine (an engine can run up to 4 axis)
1 uC (the engine runs on a single uC)
Rugged, waterproof? That's partially up to you. The more you want to push these factors, the more you'll spend. Waterproof? IP65 sealed motors alone more than triple the price.

I apologize for not posting designs yet, I had to go back to the drawing board a bit, as the shaft and bearings were both problematic after some field runs. Waiting on parts from Misumi (www.misumiamerica.com) - new custom shafts ($15 in single orders, check out their interactive design), and a new double-bearing mount ($50 in single orders). This will make it a lot easier to assemble the whole thing, and should resolve both the bearing slack issue, the difficulty in aligning the shaft, and the particulars of Sterling Instrument's worm gears.

For a look at the drive train I'm using, to get an idea of where the price comes from:

( http://sdp-si.com/estore )
S1C86Z-P064B120S (120 ratio, bronze worm gear .2495" shaft) - $25.44
S1D94Z-P064SS (steel worm wheel, custom-bored to 6mm [mate to motor below]) - $25-30 (depends on order amount)

( http://anaheimautomation.com )
15Y001S-LW4 (NEMA 15, 9 oz/in, ~ 400mA max, stepper - $21)

If you add in the $65/axis cost from Misumi, that works out to about $235/axis just in drive train. Sounds expensive, right? It would be if one didn't take into account the fact that you're getting a theoretical ~ 50lbs of torque, using ~ 350mA, almost zero backlash (one can adjust it out nearly entirely), full holding strength at no power, and 0.0019' of accuracy. If you can achieve all of that for less, please share it with us! If you know a supplier of worm gear boxes that can provide 120:1 for less than $210.00, with less than an arc-min of backlash, I'd be your best friend. =)

Here are the Misumi part #s I'm waiting on:

Custom Shaft: SFRD10-41.0-F18.0-B16-P6-N6-TA4-TB5
Mounted dual bearings: U-BASB6000ZZ-L1.00

One would also need an M6-male to 1/4-20 female mounting adapter, available from Edmund Optics for ~ $6.

Once you look at the parts outlined above, you might understand how it becomes much easier to assemble. The worm gear mounts on the threaded part of the shaft, and a nylock nut is torqued down to hold the gear - the set-screw can be laid into the threading, offering an easy and affordable high-torque mount. The shaft is only supported on one side (the dual bearing block), eliminating shaft alignment issues. Screw the threaded adapter into the drilled and tapped end of the 10mm shaft, and you can connect directly to a tripod - or you can use an M6 bolt to mount your tilt arm. Now mounting issues are resolved (and they are real =).

The frame would be made of 8020, we tried designing it just to use an acrylic plate to connect two like axes, however it was both limited in strength and adjustability. Using some pieces of 80/20's 1010 series extrusion, and a few connectors - one gets a nice frame for the kit, with the ability to do nodal adjustments, for about $60.

I'll be posting pictures as soon as the new stuff comes in and I can get it all put back together. (I just have panels laying around waiting for the new parts.) If you want to get an idea of what the original design pan axis looks like, see here: http://openmoco.org/node/100

!c