Peter Wallers Robot Ramblings

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peterwaller
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Re: Peter Wallers Robot Ramblings

Post by peterwaller »

The NAND gates arrived and I have built a second controller with them in place of the OR gates and reverted to the standard firmware.
Not only does it fix the full forward, full turn problem but the motors sit at rest when the transmitter is turned off.
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peterwaller
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Re: Peter Wallers Robot Ramblings

Post by peterwaller »

As I mentioned before most of my drive all day robots had not survived the last school fete and as I am doing a demo in the summer holidays at a local library I thought I had better get some of them updated or at least working.
Although not much good in combat my old machines with pincers is always popular with the kids so I thought I would rebuild it.
One of the problems with the pincers is that when you close them around something the servo tends to stall drawing a larger current and often burning out the cheap servo's.
Before I had a thin flexible wire link between the servo and pincer mechanism that could flex enough that the servo didn't stall but it was all a bit sloppy and prone to breaking.
I have now come up with a solution that works much better and appeals to the engineer in me.
Basically there is a brass tube push rod that connects to the servo and just reaches the pincer arm but is not attached to it so it can push the pincer but not pull it.
There is a spring around the tube that is fixed to the pincer and to the tube at the other end.
The servo arm then can pull the pincer via the spring but if the pincers don't move the spring stretches so the servo doesn't stall
Image
Here in action
https://youtu.be/82EdxPb6ZT0
Last edited by peterwaller on Tue Jul 04, 2017 9:45 am, edited 2 times in total.
Puddle
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Re: Peter Wallers Robot Ramblings

Post by Puddle »

That's a really neat solution. Nice job
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GeorgeR
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Re: Peter Wallers Robot Ramblings

Post by GeorgeR »

That grabber mechanism is ingenious, and new Anticyclone certainly looks formidable (despite the colour)!
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tomchaps
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Re: Peter Wallers Robot Ramblings

Post by tomchaps »

Robert, I've just got access to a 3D printer that can print polycarb--I believe Fortus or Forte brand?--at $5 a cubic inch. I have little idea how to estimate how much I'll be using, though--I've not tried to estimate fill and wall thickness, etc, for a combat bot before. How much filament do you end up using (by weight or volume) for a typical 150g ant?
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peterwaller
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Re: Peter Wallers Robot Ramblings

Post by peterwaller »

It varies a lot between chassis but the ones in the picture below are from left to right:
Flippant.......Alloy 910 Nylon.......24 gms
Anticyclone...Polymaker PC-Max...34 gms
Defiant........Polymaker PC-Max...30 gms
Mutant........Hi Impact ABS.........31 gms
The nylon is my favorite and probably the lowest density and usually comes out a couple of grams lighter than the Polycarb .
The polycarb is stiffer but gives off more fumes that can be a problem if working in the office.
Image
I always print with 100% fill so maximum strength and weight.
If you load your file into Cura it will give you the weight and length of filament needed and you can play with the fill density and other figures and see the effect it has on both.
By the way who is Robert :roll:
Last edited by peterwaller on Tue Jul 04, 2017 9:48 am, edited 3 times in total.
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Shakey
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Re: Peter Wallers Robot Ramblings

Post by Shakey »

I find aroundabout the same numbers as Peter, most my printed chassis weigh between 20-40g.
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Re: Peter Wallers Robot Ramblings

Post by tomchaps »

Great, so at $5 per 20g, that's a totally reasonable cost. Woo. (Now I just need to learn CAD from scratch...)

Peter + Robot = Robert, in my sleep-deprived brain. Sorry!
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peterwaller
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Re: Peter Wallers Robot Ramblings

Post by peterwaller »

As you may have noticed all my picture links now fail.
This is because Photo Bucket who have hosted them since 2006 has stopped allowing 3rd party hosting unless you pay them $399 a year which seems like extortion to me.
I need to work out how to proceed but in the mean time if you right click on the dial and select "open image in new tab" it does seem to go to the picture all be it in a new tab.
That's weird having played around opening up images in new tabs some of the images are now displaying .
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GeorgeR
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Re: Peter Wallers Robot Ramblings

Post by GeorgeR »

That must be pretty annoying given how many pics you've got there. Unfortunately i don't think that photobucket is worth bothering with anymore, but I can recommend Imgur as a very good replacement.
Team Zero - AWS 58 Champion!
Zero - rambot - - Axiom - axebot - - Valkyrie - drum spinner
Blueprint - rambot - - Vampire - horizontal spinner - - Particle - ???
RBMK - quad spinner gyro walker - - Duality - dual spinner gyro walker
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