Team Aggregat's Build Diaries

Hi all,

It's been a little over 10 years since I last built a featherweight (and that wasn't really up to much, I only went to one event with it), so I thought I'd start a build diary for my new featherweight. It's a scaled up version of my antweight, 'The Mole'. Working name is EnorMole.... But any suggestions for large mole related names are welome. :P This is the original Mole:

https://lh6.googleusercontent.com/-8...0/IMAG0144.jpg

I'm planning on keeping it fairly simple and am hoping to get it ready for Newport on July 20/21. The chassis is a mixture of 12mm and 10mm HDPE, with 4 drill motors. I'm currently testing on a 3s lipo, but will be using a 5s for the first event. Speedos are a bit ancient, they're some old 30A electronizes with the external relay mod that I pulled out of the shed, although it's only a matter of time before I get some Botbitz 85As.

Anyway, first step was to get the drills and strip the motors out of them and grub screw down the clutch. For the wheels I've gone for some 1/8 buggy wheels. I fancied something different from the blue wheels or banebots wheels, and also I needed something that looked a bit like the wheels on the antweight version of The Mole. They don't seem particularly rugged or grippy, but they'll do for the meantime. They're attached to the motor shafts via 17mm hexes, which fit onto the motor shaft via a 17mm nut with a 3/8" UNF thread.

https://lh3.googleusercontent.com/-2...0/DSCF0566.JPG

https://lh5.googleusercontent.com/-X...0/DSCF0563.JPG

Next up was some motor mounts made out of 12mm HDPE. Cutting the rear bracket was easy enough, but the front one was a bit of a pain. I'm pretty low tech when it comes to robot building equipment, but after lots of drilling, sawing and filling they all fit and are ready to be bolted onto the base plate. I'm sure there's probably an easier way to mount drill motors, but this seems like a pretty sturdy solution. The base plate is 40cm x 50cm of 10mm HDPE.

https://lh3.googleusercontent.com/-w...0/DSCF0586.JPG

https://lh4.googleusercontent.com/-V...0/DSCF0589.JPG

https://lh3.googleusercontent.com/-3...0/DSCF0593.JPG

The side panels have been cut from 12mm HDPE, as opposed to the 6mm HDPE I used in the antweight version. Next up was to cut some holes in the base plate for the wheels. They're not the tidiest edges as all I have is a jigsaw. Next up is to screw the motor mounts and side panels onto the base plate, then get the speedos all wired up.

https://lh3.googleusercontent.com/-M...0/DSCF0594.JPG

The main aim is to get something up and running for the event at Newport, so it will just be a basic 4wd pusher. But i reckon I'll have 4/5kg to play with, so I was toying with the idea of having interchangeable top panels with different weapons. I'm going for a simple axe first, then the plan is to make an interchangeable spinner module ready for the championships next year. At which point, I'm firmly expecting it to get destroyed, and then I'll start on a proper featherweight. I see this one as more of a learning experience.

Sorry for the lengthy ramble, but I do really enjoy reading other people's build diaries, so fancied doing one of my own. I'll be posting further updates for my feather, and also info on my Antweights and the upcoming Beetleweight build (as soon as the parts arrive). Any advice or comments welcomed! :)

Cheers,

Rhys

So far so good. Those wheels look pretty grippy and it does make a nice change from the banebots/robochallange.
Looking forward to the beetle!

Looks very nice so far, better than anything I could do. As for motor mounts, what I believe is the easiest way, is to attach P clips to the front and rear of the motor, and use blocks of HDPE to raise it up. Cheap, effective, the only way I can (Bar Zipties). I haven't put them into practice as of yet, but I'd still have a look at it for future projects.

Looking good so far, very nice :)

The only thing I can offer as a suggestion for the front drill mounts is to simply cut a rectangle rather than the oval-ish shape that matches the drill gearbox case. I did what you've done in 20mm Nylon for the drill mounts in the first Drumroll and it took ages!

If you go for the rectangle, just mark it out to 30mm x 25mm and cut it with a jigsaw. Easiest way to do that is to start off by drilling a hole in each corner of the rectangle big enough to fit your jigsaw blade through (I find 8mm works well) and then just cut from corner to corner. Means you can just cut in straight lines rather than having to worry about doing curves with it. Just make sure to cut on the inside of the lines you've marked, so that you're more likely to have a tight fit that you can rasp/file down rather than a loose fit that's difficult to 'undo'.

And as someone who often makes long, rambling posts, I say the more the better :)

Looking good so far :)

and theres nothing bad about electronize! They have served me well for 8 years and still both work haha, even if the robot does have the most inaccurate drive in the world..

@Jamie, don't the gearboxes just spin in the mounts? I imagine cutting a square would allow too much play.

The way I do it is I drill a hole that's the height of the gearbox (25mm?) and then with a curved edge rasp file out the sides, and with a flat one the top.

Hey Mr Duff. Its Marco here from times long past! Hope you are well.
Featherweight is looking great so far. 4 bar lifter would be cool and you should definetly have some weight to spare. I had electronize for a long while but one started to fail (possibly a sticky relay). I upgraded to a scorpion XXL which worked nicely with 4 drill motors.
I have mounted drills like that in the past and it didnt work out too great. After a big flip I ocasionaly landed on one wheel and that often stripped a gear internally. If I were to use drills again I would brace the wheel on the other side. Bit of rod or a roller bearing.

Aside from that, good luck! See you at newport :)

Quote:

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Originally Posted by PJ-27

@Jamie, don't the gearboxes just spin in the mounts? I imagine cutting a square would allow too much play.

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Only if you cut it too big, and even then, the gearboxes will only rotate by a couple of degrees. Here's what you're effectively doing:

Attachment 3837

So instead of cutting it to perfectly mate with the drill, the four corners (blue bits) are now just gaps. The properties of a rectanlge mean that it's not possible for any rotation to occur because the top and bottom are restrained in a gap of 25mm and the left and right sides are restrained in a 30mm gap :)

@Jamie, good point. Plus what with you drilling out the corners before cutting the straight lines you could add even more contact since the hole will have a radius.

Cheers for the comments guys. I realised the rectangle thing just as I was filing down the motor mounts. But I guess its only a one off job, so I didn't mind spending some time getting it right.

Marco, its been ages! I think you were at my last featherweight event all those years ago! I think the last time I saw you was at AWS 18 or something like that. So I take it you're coming to Newport too then? And as for the electronize, mine had a dodgy relay a few times, hence the external relay mod. The botbitz look in a different league though and are much cheaper. I think I'll wait for these to die first though.

Quote:

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Originally Posted by RogueTwoRobots

Only if you cut it too big, and even then, the gearboxes will only rotate by a couple of degrees. Here's what you're effectively doing:

Attachment 3837

So instead of cutting it to perfectly mate with the drill, the four corners (blue bits) are now just gaps. The properties of a rectanlge mean that it's not possible for any rotation to occur because the top and bottom are restrained in a gap of 25mm and the left and right sides are restrained in a 30mm gap :)

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That's exactly what I've done in Loki :)

Quote:

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Originally Posted by duff

I think the last time I saw you was at AWS 18 or something like that. So I take it you're coming to Newport too then? And as for the electronize, mine had a dodgy relay a few times, hence the external relay mod. The botbitz look in a different league though and are much cheaper. I think I'll wait for these to die first though.

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Yeah it might of been Debenham that I last saw you, I built a featherweight ram bot which I dropped on the way to the event and broke an electronize. Or the giant wooden skateboard robot? I have also been out of the loop till recently. Havnt built a new robot in 4 years.
I havnt got my 85a bot bitz speedos yet so cant recomend but if they do the job then I cant see the need for a scorpion XXL.
Yes I will be a newport. Liz and I will be there a week after my marriage funny enough so its my honeymoon!

Convince her to spend another week there and you can cone to the AWS too! ;)

Not sure if this belongs in a build diary, as I've not actually built anything yet, but all my Beetleweight parts arrived today! Very exciting. Pictured below, from left to right:

- 4mm steel plate, which the disc will be cut from.
- This 815w brushless motor
- 4s 1300mah 25-50C nanotech battery
- 60a Brushless ESC for spinner motor
- 2 x 20a brushless ESCs. I'm hoping to hack these myself to run the brushed drive motors.
- 2 x 12v 500rpm motors from ebay

Coin, ruler and antweight are all just there for an idea of scale. :P

https://lh3.googleusercontent.com/-4...0/IMAG0185.jpg

I'm still unsure as to how to mount the disc. I was considering mounting it onto the motor shaft directly with a prop adapter, as I've always done with my ants. I've never had any problems, but I know there's much more energy in a robot of this size. Ideally I'd like a timing pulley system, but that's a extra expense, weight and call for tools and expertise that I don't have.

The drive motors look promising considering they were pretty cheap. Here's a quick comparison with the standard sanyo type antweight motor:

https://lh4.googleusercontent.com/-Y...IMAG0187_1.jpg

They're rated for 12v, so I'm hopeful they'll be ok on 4 cells. They're only £6 each with free P&P from china, and they only took 8 days to arrive. Fingers crossed they're decent as they look about perfect size for Bettleweights. Building won't start for a few weeks yet as I'm busy finishing my feather and getting antweights ready for the next AWS. But as anything gets done, I'll post it here.

Looking good. We've gone for similar sized motors, although mine is slightly more powerful and has a higher KV. That should make for some interesting weapons! I'm really interested in what you end up building. Any chance of making it to Deeside?

I should have it built by then, its just a case of if my car will be able to make it that far. Its being a bit of a t**t at the moment, and I suspect it might be dead by then. But I'm starting the build as soon as AWS 41 is over, so that should give me plenty of time. I went for the lower kv as I was thinking of going direct drive. If I do end up going for a pulley it will likely be 1:1, or something very close.

I could pick you up on the way through if you want?

A nice POP, best of luck with the ESC hacking.

I don't think direct drive is the best option in this weightclass due to the greater forces that you mentioned, though it may be worth trying it to see (just stand well back incase it fails). As an alternative to timing pulleys, what about mounting the brushless motor vertically, attaching a wheel to it and running friction drive?

Don't think it's been done in that orientation before and doesn't call for as accurate a setup as traditional transmission methods; just have the motor mounted to a hinge that's sprung in such a way that it keeps a constant pressure on the disc (to account for wobble in the disc or wheel). You can then adjust the speed/ratio by varying the wheel size or how close to the disc's centre you put it.

Quote:

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Originally Posted by psychostorm

I could pick you up on the way through if you want?

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Ah, really? That would be awesome, cheers mate.

Progress has been slow, but I've finally got Enormole all wired up and working. I'm not the best at soldering, and I'm pretty slow at it, so I had to clear an entire evening to get it all done. The worst part was getting the external relays on the electonizes all wired up. It seems like such a waste of time as I know I'm going to use TZ85as some time in the near future, but I guess I need something for the interim. I was going to solder new wires onto the motors, but lost patience and just left the standard drill wires on there. Maybe that'll be a job before the next event. At the moment I just want to get it ready for Newport.

https://lh3.googleusercontent.com/-g...0/DSCF0601.JPG

https://lh6.googleusercontent.com/-e...0/DSCF0604.jpg


It's starting to look a bit more like a proper robot now. There's still loads to do before Newport though. First off, the 3 cell battery is geting replaced. I fancied a 5 cell, but looking at its current performance on 11.1v, I dont think 18.5v is necessary. I may just get a 4 cell pack now. Judging from the video, what do people think?

Then I need to build a case for the lipo. Am I right in thinking that we now need a metal cover all around the battery? Is 2mm ali going to be enough? I really don't have the tools to do much steel work. I also need a link, fuse and LED, but these should be easy enough to sort. The side panels are already cut and just need screwing on. Same goes for the scoop and front wedge, and it'll be done. I'm not expecting much in my first event, a wheel came loose even in testing tonight. But I've learnt so much already, and I've not even made it into the arena yet, so I'm hopeful for my 'proper' featherweight, which will be started at some point after next years FW championships.

It doesn't drive too bad for something I've kocked up in a few afternoons. It certainly had a bit more punch than I was expecting (hence potentially dropping the 5 cell idea). But I guess you can't judge much in a small space like this, I'm sure it'll seem underpowered when it comes to a real fight.

http://www.youtube.com/watch?v=h_rtjFQPywE

As usual, comments/criticisms greatly welcomed! :)