Team Dudge build diaries.

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Derek Dudge
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Team Dudge build diaries.

Post by Derek Dudge » Thu Jan 11, 2018 2:32 pm

Hi again folks :D

So since I last posted I have been busy doing what parts I can of Robot build number 1. I'm still waiting to hear about the nano kit, and have begun thinking about alternatives just in case, but in the meantime I got to work on the bits I could, namely the polycarbonate bits.

I now have a body for the robot to live in!

Now, I just wanted to say real quick. I read on here several times before I started "oh, that 1.5mm poly, easy peasy, cut it with scissors, bend it by hand no problem at all". Well. Phooey. Easy isn't a word I'd have chosen haha. Several nipped fingers, a bunch of swear words, and three sheets of trial and error later, ehh, I guess by the end I'd kinda got the hang of it. My last few goes at bending were much better than the first lol. I broke a pair of scissors too! Easy to cut and and bend, my bum. I did it though!

Worth me mentioning again - umm, this is not a super high tech project. I bought a cheap knock off dremel drill, a pack of sandpaper, and a clamp. I don't have a workshop or much experience at all with this stuff. Go easy on the new guy haha. My last experience of workshop/electronics was terribly run GCSE classes, which was... a few years back now. I'm learning and relearning a bunch though.

Anyways on to the robot!

It's gonna be 4wd invertable push bot, keeping simple this first time. There'll likely be other more complicated projects (my housemate is also a huge fan and probably when this one is done me and him will make a 2nd) but first time round I've got enough on to be learning as it is.

Working name for the little guy - Third Law. Thought it appropriate for a pusher robot who's game plan will basically always be - drive at the other robot head on again and again and again. Please do let me know if you guys know of another robot who pinched that name already hehe.

My whole plan was to go for strength/resilience on the front and rear facing. I've seen lots of videos of the spinning weapons people are squeezing into 150g, and damn... So my intention is make something that can survive driving head on into one of those :D get some of that equal/opposite jazz working and try to out tank the weapon. My thinking is that with 4wd I ought to be able to shove back pretty well.

Also the sides (and more importantly the wheels) will be well covered, though side on the build is nothing like as strong as front to back. Really i feel this thing is for head on collision.

The weight of the thing bolted together - approx 65-68 grams. I last weighed it before I'd finished the lid part so I have to rough it to about 68g. Should hopefully fit into 150g with a nano kit, battery, etc. I've done an estimate and will be very close
Maybe I end up needing to drill a few holes.

Dimensions - it should *just* fit into the cube on diagonal. 122mm long, 96mm wide

Hopefully soon this diary can turn to internal stuff. I think, for now, I've done what I can.

Some pictures!

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Last edited by Derek Dudge on Sat Mar 10, 2018 3:32 pm, edited 2 times in total.

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GeorgeR
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Re: First time building diary: Third Law

Post by GeorgeR » Fri Jan 12, 2018 1:07 am

That's looking good and solid, and it sounds like you've got the weight about right. If it ends up a bit overweight a good tip for saving weight is making sure the bolts are just the right length, I saved the final 3g to get my axebot to 150g by using shorter bolts.

If your looking for an easier way of cutting polycarbonate i can recommend a pair of aviation snips, they are designed for sheet metal but work great on polycarbonate too, I use these ones from screwfix which are nice and cheap. Those and a pair of wire cutters for more intricate cuts are my main tools for polycarbonate.
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Zero - rambot - - Axiom - axebot - - Valkyrie - drum spinner
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BeligerAnt
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Re: First time building diary: Third Law

Post by BeligerAnt » Fri Jan 12, 2018 7:43 pm

I think it's fair to say that cutting 1mm polycarbonate with scissors is easy enough, but that extra half a mm makes all the difference! Tin snips and wire cutters are a good suggestion for when the going gets too tough for scissors.
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Paulmchurd
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Re: First time building diary: Third Law

Post by Paulmchurd » Fri Jan 12, 2018 8:34 pm

What about a hack saw?

Derek Dudge
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Re: First time building diary: Third Law

Post by Derek Dudge » Fri Jan 12, 2018 8:43 pm

Haha yeah I was just being a bit daft in that bit about cutting and folding the stuff. It was more difficult than I expected but really half of the problem was me using scissors that weren't quite up to it. Hopefully I've cut all the poly i need for this project now, but next time I would definitely invest in a pair of those snips linked up above.

Quick question that I'm sure one of you guys could answer that doesn't really need a whole separate thread.

Do the wheels from the nuts and bolts webshop count the type part in the 30mm? Or is it 30mm plus tyre?

Cheers!

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Re: First time building diary: Third Law

Post by James Bennett » Sat Jan 13, 2018 10:18 pm

The 30mm is including the tyre, I just measured a couple and its about 31mm to the edge of the treads.

I have found that it is often easier to score polycarbonate with a knife and snap it, rather than using scissors.
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FoxFire
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Re: First time building diary: Third Law

Post by FoxFire » Sat Jan 13, 2018 11:38 pm

Liking the look so far :) What kind of drill did you use for the holes and screws?

Derek Dudge
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Re: First time building diary: Third Law

Post by Derek Dudge » Sun Jan 14, 2018 12:31 am

I used a cheap dremel style grinder/drill tool that I got from amazon for a tenner. It's probably a get-what-you-pay-for level of quality really but it drills Polycarbonate okay

So, nothing new to show pictures of but...... Tonight I ordered a nanotwo ESC and 4 of the tough hub wheels from the nuts and bolts site, and 4x 30:1 6v micro motors from another site (sadly these are out of stock on the N&B site.

I was a little confused as to how all 4 motors connect to the ESC but Alex explained a bit in an email and I'm feeling ok about that again now.

Things I still need to buy:

Batteries & charging/safety bits
Soldering iron (the esc will need soldering to the motors now its not a kit per se)
A few wires and other miscellaneous internals bits such as a little switch
Transmitter handset.

Might have to wait until end of the month now to finish shopping, but at least if the motors are delivered fairly quick I can work on mounting those.
Last edited by Derek Dudge on Tue Jan 16, 2018 12:54 pm, edited 1 time in total.

Derek Dudge
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Re: First time building diary: Third Law

Post by Derek Dudge » Tue Jan 16, 2018 12:49 pm

Small update. Had a little time to kill so I swiss cheesed the lid in anticipation of being very damn close to the weight limit. I could do a ton of holes in the base of the chassis if more is necessary. It probably will be.

And yay, motors! They are cute little things, huh? Tiny gears.

I got the esc and wheels coming probably next week from nuts and bolts, but I'm glad the motors came quickly because now I can keep working on it in the meantime figuring out where and how to attach them. Gotta rise them up from chassis base so the wheel centre is halfway up the thing.

Might need to get a little hot glue gun.

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MrEnDo
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Re: First time building diary: Third Law

Post by MrEnDo » Tue Jan 16, 2018 10:29 pm

Nice build so far!

Where did you get your motors from?

Derek Dudge
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Re: First time building diary: Third Law

Post by Derek Dudge » Tue Jan 16, 2018 11:42 pm

From hobbytronics. They were more expensive than some I saw on ebay but I didn't want to wait weeks for shipping.

I have been fiddling around trying figure out how to mount the motors up. And i have a plan now.

Kinda a stroke of luck, that turned onto their side, the mounts that came with the motors are almost spot on tall/wide enough to have the peg where i need it so the wheels are halfway up. It's very damn close. Within a mm. I'm not gluing anything until i have the wheels to double check, but at most a sliver of plasticard or something might have to go under.

I gotta stick a bracket to each mount to do it this way.

I attached a picture of a hasty mock of what I'm thinking. Please excuse, I had to draw the lines on my phone.

My plan: is yellow line needs to be cut/filed away a bit, so it fits underneath the lid.

Green lines will be hot glue, attaching the mount to the bracket and then all of it to the chassis.

Blue line will be a removable plasticard or tape flap, to stop the motor moving around inside the mount, but allow the motors to still be removed if they get damaged etc, since the mount and bracket will be stuck down.

So.. I guess my question is, you guys think those hot glue joins will be strong enough?

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MrEnDo
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Re: First time building diary: Third Law

Post by MrEnDo » Wed Jan 17, 2018 7:48 am

I wouldn't of thought hot glue would be strong enough, maybe epoxy glue?

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peterwaller
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Re: First time building diary: Third Law

Post by peterwaller » Wed Jan 17, 2018 8:59 am

I normally mount my motors using the two threaded holes in the face plate.
You need the mounting to have a 4.6mm hole for the shaft bearing and two 2mm holes 4.5mm either side for the mounting screws which are M1.6 by 4mm long. Don't make the screws any longer as they can reach the gears and lock the motor.
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MarkR
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Re: First time building diary: Third Law

Post by MarkR » Wed Jan 17, 2018 12:08 pm

I see that there are various motor mounting options; I like the idea of using a plastic (maybe 3d printed, or bent polycarb) mount, then making "wrap around" wheels which overlap the gearbox.

I saw that technique on a youtube video, it looks like quite a neat idea to save length on the gear motor.

Create a hollow wheel that can slide all along the shaft then wraps around the gearbox.

But most of my parts for antweight haven't arrived yet, I've not built one before :) (but I have built bigger non-combat robots)

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Phil_8
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Re: First time building diary: Third Law

Post by Phil_8 » Wed Jan 17, 2018 4:06 pm

Trim those bolts to save a load more weight too!

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