8020/Acrylic Worm-Gear Pan and Tilt Prototype

Thanks Slau - this is the kind of design I was talking about. It's not the cheapest in the world, but overall value is amazing. (Weight to performance, cost to flexibility, power consumption -- the worm gearing allows power kill between motion, so batteries are only consumed by motors when actual movement is needed. This also allows really pushing the steppers, so those tiny steppers can run up to 10lbs of kit!) It's not as big as it looks in the picture, either. It only weighs about 6lbs. The final design will remove almost 1 lb of weight from it. Removing the camera arm allows it to easily fit in a LowePro CompuTrekker pack. If one doesn't care for nodal centering, another lb or 2 can be shaved off. The other neat thing (not shown)? You can quickly invert the tilt 'tower' on the pan base by adjusting two bolts -- allowing one to put the camera outboard of the pan, allowing for full 360' tilt rotation.

The primary changes waiting to be made are in the shafts and bearings. If the new changes work great, the only thing that one couldn't order from a vendor from existing stock tomorrow would be the acrylic panels. I'm figuring for someone w/o the tools or wherewithall to make them themselves would run about $50 for laser-cut service.

Anyhow, the design changes are that the shaft part supporting the weight will be increased from .25" to 10mm (0.394") and all of the hubs will be eliminated by using an M8 bolt to attach directly to the center of the shaft (Edmund optics sells an adapter from M8 to 1/4-20 for about $5 for attaching to tripods). The hubs are major source of cost and frustration.

Additionally, to eliminate the issue of the set-screws on the worm gears, the part of the shaft that the worm gear is mounted on will actually be M6 threading. Since the shaft will step down from 10mm to M6 threading, there'll be a nice face to press the gear against, and then a nylock nut is used to compress the gear against this face - virtually eliminating any slip under any torque level, and not requiring constant re-tightening when one elicits too much torque on the arm.

This also, implies that _anyone_ could put it together with a few basic tools. No custom work needed!

The shaft would then be supported on only one end, by a dual-bearing support (10mm bore size), eliminating mis-alignment issues and increasing the strength of the bearings against downward/sideward force.

!c

Yeah, you just set the sleep pin on the ED's (or whatever driver). The nice thing about a sleep function, is you only really need one pin. It would be a waste of pins to have separate statuses for things that rarely change. So, just use a switch on each driver - use this to override "sleep" for any axis that shouldn't sleep, and then you just use one pin for all drivers.

The Camblock design works fine from what I've heard. The problem putting everything in one box (as camblock does - not just motor and gears, but also some electronics) is that everything has to be what it's designed for to get that compact design. Making one change means you have to re-design the enclosure. Which is fine for most people's projects, but by trying to provide a starting point where anyone could start from, with parts anyone can buy, makes it a lot harder to make things more "generic". In this case, I separated the drivers from the axes (not shown, but in little black boxes that bolt onto the extrusion), and put the motors on the outside of the gear box. This way any NEMA15 motor can be used with the design, not just the little 1/4 stack-length ones I've chosen. And, of course, if someone wants to upgrade their motors, having the drivers separate means they can upgrade those too without re-designing the whole thing.

Putting them all in one box tends to make things more compact, definitely. I would approach that route if that's your need. However, if you feel you're going to experiment with different hardware - I'd suggest going more modular in the overall design. It will save you lots of headaches and boxes of useless panels =) Here's a real example I experienced:

I originally put my drivers inside of the enclosure, with the motors inside too. I designed a circuit board for the ED's, that had inputs/outputs/ and chains through to another controller (one cable to run two motors). I machined in the mounting holes for the driver's carrier board, and a hole to adjust the current limit pot on the ED. Everything was great, until I got to assembling, and then realized that the side I had placed the hole in required me to have proto board that was copper clad on both sides - which I didn't, and the headers/wiring I used prevented me from being able to mount the board upside down w/o hitting a gear, and then no entry could be had from the top side because a gear blocked the pot! Oops! I had to open up the enclosure every time I wanted to adjust the stepper.

So, while I'm leaning towards more general designs to share - you can make it as specific as you need for your application, I'm just trying to reduce the points for mistakes as I share my designs - even if that means they're sometimes a little too simple for most people's needs. =)

!c

Silly question, but I've got ask... *grin* Why not just put a normal setup inside of a big, watertight, acrylic box? Seems like it'd be way cheaper that way, unless you have other requirements. (Not to discount the coolness factor, in any way =)

Can get anything machined out of aluminum around here, I take it you're in NL? Not sure what the machinists scene looks like there, but there are about 50 machining shops within a few miles of my house, caveat emptor... *grin*

If you really wanna spend some bucks, but wanna go easy - there's emachineshop.com, can use their CAD software for free, and then, if you like, have them build it. I use their CAD, 'cos it's easy as all get-out, but do the machining myself.

!c

... and that's why I'm not a diver! Being of the mind I normally inhabit, I would just throw a bunch of lead bricks in there and let whoever had to get it back to the top to sort things out, hehe.

!c