Apr 27 2011

Camera, motor, kittens

Going through the workshop, making small improvements and sorting some things out.

For one, after several months of it bothering me, I knocked together a better mount for the angle-poise webcam.

Doesn’t look like much, but now the tilt is on top of the pan pivot rather than the other way around. The previous one was smaller but meant the image was only level when looking directly forward (along the line of the arm). Turning to show what I was doing to the left or right meant the image turned on it’s side. This way the image should remain level and I’ll be able to manuver the camera closer to the action.

In my sorting, I also scrapped some broken battery drills that either had dead batteries, broken chargers or damaged electronics. So I have four sets of low-voltage motors with reduction gearboxes and torque-limiters, and one electric screwdriver with just the motor & gearbox.

I haven’t checked yet, but Wikipedia suggests about the maximum torque you can expect from a battery drill is around 30Nm.

I’d been considering using them to make a large track-mounted robot arm, but at only 30Nm it’s unlikely they’d be able to make the arm move under it’s own power, let alone do anything useful.

If I packed out the torque control spring I could have them continue to run at higher levels, but I’ll still need more powerful motors I suspect. I’ll be looking into what’s cheaply available. Initial enquiries suggest radio-control vehicle motors won’t have enough torque. Steppers may be another option.

I’m envisioning something of a comparable reach to that of a human arm, so about 30cm between joints.

And finally, we still have some kittens looking for good homes.


Apr 27 2011

Eye-blank developements

I’m glad to say there’s finally some good news on the eye-blank front. A few recent castings have been coming out crystal clear! The new epoxy resin is starting to work out.

It’s crystal clear, without the yellowy tone of the eurethane clear-cast and without the blue hint of the noxious styrene resin.

The only issue is that it’s rather harsh on the silicone moulds, clinging to them very tightly. Mould-release has helped a bit but has also left the blanks with a slightly “frosted” surface.

I have some test blanks currently curing in hardier urethane-rubber based moulds, which hopefully will not require mould release. If they come out as well as I hope, I should be able to start production proper within the next fortnight.

A urethane mould curing

The experiments continue. More updates should soon follow. For science!

PS: Site gallery and previous post images may not respond correctly for a while as I shall be making alterations to the gallery plugin the site uses.

Apr 27 2011

Twitter Updates for 27-04-2011

Apr 26 2011

Twitter Updates for 26-04-2011

Apr 25 2011

A reason why they’re cheap

I found another couple of battery drills being thrown out last week. One Power Devil and one McKeller.

The Power Devil is the usual bottom-rung battery drill, though looks like it’s been fitted with a replacement chuck.

I opened up the battery pack, and it was pretty much what I expected.

Mostly empty.

The McKeller on the other hand was much nicer and more powerful. However neither drill had a charger unit, so they’ve both been stripped down to motor and gearbox. I’m thinking they could be good for making a reasonably powerful robot arm.

The chucks on all of them attach with a 24tpi UNF thread. I might have to belt-gear them down, but then again PWM control would probably be fine and simpler to attach.

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