Pulverizer Build Diary

[Max]

Your links dont seem to work without copying and pasting it into the url bar so its hard to check all your parts. I think you may have unchecked the box " Automatically parse links in text"

It will be very expensive getting all those parts laser cut and I doubt 10mm aluminium will laser cut very well as I imagine it will melt. I would still suggest starting simpler just making a cheap rammer/wedge/lifter as you will learn a lot about being at an event and about what works in a robot, you don't want to spend lots of money to find it doesn't work or gets destroyed in its first fight.

[Mega Masher]

Max, what about 3mm stainless steel. And max, no offence, but I'm not just gonna give up on this idea. Ive seen the rammer bots, bit I want to build something never done before in the uk (I think). I'd much prefer to try hard to build a good bot than get a not-so-good one built in 10 mins. See what I mean??????
Pinski1, research melty b, it shows you what it is used for. The robot reads a value from the accelerometer, and from there works out the speed it is spinning at, then lights up an led to light up the "front" of the robot. Then it can turn on or off a motor dependant on where it is in each rotation to make the whole bot drift in the general direction I tell it to with the controller. Hope that helps. Btw I can't use tz85's as I need to give the motors 70amps continuously and up to 190 for stall current. Tz85's can't do that.

[Pinski1]

Ah, right, I see what you're planning now. Neat. I must admit without wanting to go further into the maths behind "melty brain" robots it seems a gyro would be a better choice. *shrug*

I'd definitely advise against using a DIY speed controller just because it's very hard and expensive to make something that is as reliable as the £30 TZ 85As.

[Ellis]

You can get aluminium watercut quite cheaply.

Unless there's a huge shell to go on this, a 10mm end-tapped (meaning no finger joints or anything) aluminium box structure doesn't sound very sturdy as the exterior of the robot. It would be fine for a regular style machine, but one which is spinning is going to attempt to skew the chassis; squares are inherently weak in the direction of forces this shape would suffer.

Do you intend to attach teeth directly to this chassis or is there a shell to go around that just hasn't been designed?

[Mega Masher]

Pinski1, yes, you could use a gyro, but it would have to be an optical gyro, which is very expensive.
Ellis, I see what you mean, but I'm not sure what I could do to solve the problem of it not being to strong. I could add in bracing or something like that. What shapewould you recommend????

[Ellis]

Well, triangulating the corners with "gussets" would help, as triangles are strong and resist compression a lot better than squares. But then, a circular body is probably the most efficient shape, in terms of strength/weight, as well as it seems logical for a spinning robot (hence others tend to build fullbody machines round or near-round polygons). I don't know the maths, but there's a chance the wind resistance of a square will make for quite significantly reduced electrical efficiency, and a circle, apart from the teeth surface area, doesn't suffer this at all.

I realise it's harder to work with a ring design with the average set of tools, but it might be worth looking into what you have available. If there's a scrapheap near you, a rummage around might bring something up, some steel drainpipe or something could be an ideal starting point. In the past I've had thoughts about using a motorcycle wheel hub as the basis of a full body on the cheap.

[Max]

Ok, just another thing, it looks like you are only getting the dewalt motors without the gearboxes- you need these unless you are going to make a large external gearbox.
You need one of these for each motor:
http://mobile.robotmarketplace.com/0-DEWUT.html

[Mega Masher]

Btw, Monster Shred!!!!!!!!!!!
http://i1280.photobucket.com/albums/...ps24ca3bbd.jpg

[Mega Masher]

Max, I'm not getting those as I'm going to make my own using pulleys-see my post of the parts list a few hours ago. Max, we've already discussed this earlier in the thread. I do actually do research myself you know!
Ellis, good idea, will have a think about that. I think that triangulation would help loads, but wind resistance is very important, and may slow the bot down. I only chose the rectangular shape for it's compactness and the fact that it would be easier to make.

[Eventorizon]

I don't like to do this but this will not work.

Those motors do 21'000 rpm ungeared. with the 14T and 36T pulley reduction the drive shafts are doing 8166RPM. With your 73mm wheels your robots top speed is 69.8mph... that is stupidly fast. That is uncontrollable to the extreme. And that isn't taking into account the speed when spinning. Most machines don't go over 10 or 12mph.

I have used that accelerometer in university projects and you will require custom programming to make it work with your set up. That in itself may be months of work to make sure it is safe and reliable. You will need an on board processor as well. If that gets damaged your machine will be useless.

Finally, going by the name you have found the US bot 'Death by translation'. That machine took 3 years to build by 2 very experienced engineers and a dedicated software programmer. And after all that it wasn't very effective, even in a large arena. In the Robochallenge arena you will never get it up to speed before you are hit by another robot.

Full marks for trying to be different but there are a whole bunch of reasons why no one has bothered.