great minds think alike
But not necessarily do alike. I spotted a similar toy myself this week and pondered about servos as well. Great to see you actually hacking into it, satisfying my curiosity.
As before with writers, the conondrum is about range vs precision. Or size vs resolution. (she said what!??)
Changing te gear ratio should give you full reach across the tablet. Worry about precision later. It takes only a very few vectors to write "LMR".
Welcome back my dear toy hacker!
8ik
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Quandry
Yes. In fact, I’ve already decided that the gear seen in the photo above is not going to be suitbale. In fact, I think I’ll make it a 1:4 instead of a 2:1. Can’t immediately see a way of attaching the damn small gears to the servos, though.
Ahhh
Well, NOW I have! That’s a very real possibility.
Here’s a question: my experience of these is that the “mechanical interface” is a slotted screw. I don’t see an easy way to attach to it. Any thoughts? Have you seen others with a more useable interface?
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Now THAT is the million
Now THAT is the million dollar/pound/yen question! How to mount things to other things that arent meant to be mounted there?
I have 1 here that has a tiny brass cap with a slot in. I don`t know what it takes to solder to brass but maybe you could solder or araldite a pin into the slot, which would give you a basis for fixing a sprocket on.
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Good point
Brass, you say? I’d use ordinary lead/tin solder! I just need something to which I can solder it. Hmmm… A brass 3mm bolt…
Hmmm
Good point. I wanted to do this on the cheap, with stuff I already have, though.
Wait a minute. I think I HAVE steppers…
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Extending Servo Range
I recently had a project where I wanted to extend the servo range. I used 10-turn potentiometers (full size, not trimpots). You can see it on this instructable (http://www.instructables.com/id/Low_Cost_Hobby_Servo_XY_Table/) and the site (http://www.teletoyland.com/Projects/Sandbox/How_it_Works/index.php). Also, timing belts may be easier to do mechanically than gears - much wider margin for error. They make smaller timing belts than we used.
Rock on
Yep. I dug out some old Astrosyn steppers. They have very little torque, but they only draw 200mA at 12V, so I can drive them with a ULN2803. I thin kthese came out of a one-armed bandit.