Team Invade's Build Diary

[Team Invade]

Re: Team Invade's Build Diary

Considering the last feather we built was Explosion back in late 2007/early 2008, and we've still got all the parts for the new Invasion which never happened, I thought it was about time we made a new one.

However, this time my Dad can't be bothered, excuse was something to do with him being too busy with one heavy and two feathers to maintain, so this one I'm building by myself.

So I've already got:
2x Feather Gold motors
2x 4Ah lipos (one spare)
1x Sidewinder
3x RoboChallenge wheels (we've lost one somehow)
Various amounts of HDPE
Various amounts of Hardox

But we've already got a pusher, so I'm going to order a brushless setup and try a spinner this time

So, first progress:





The first thing I did was cut the 20mm bulkhead (last weekend). Back then it was going to be a drum spinner (hence why it is so long), but I've changed plan to a vertical so they'll be shortened, but I'm leaving them for now as I'll probably have changed my mind again by next weekend. I had my first go on the lathe this weekend and made the aluminium spacers, turned down the wheel and pulley and bolted them together. The outer HDPE is only 10mm but it'll be wrapped by Hardox when finished so it should be fine.

Did a quick test by plugging it into the lipo and all seemed fine. It's only running on 5S so I think the 3:1 reduction should be fine.

There are a few things left to do such as shortening the axle, shortening the screws that fasten in the motor and adding some bearings, but that shouldn't take too long so I'm hoping to start the next one next weekend

[typhoon_driver]

Re: Team Invade's Build Diary

If that's HDPE that you are using then I would swap it to nylon.

[Team Invade]

Re: Team Invade's Build Diary

Yes it is HDPE. The drive pod feels pretty tough though so I think it should be fine. I think I'll probably use nylon for the spinner bulkheads though as I'm going to have to buy a new sheet anyway and I think the HDPE may be too soft.

[typhoon_driver]

Re: Team Invade's Build Diary

That should be fine. I was concerned that you were going to support the disc axle with hdpe

[Ellis]

Re: Team Invade's Build Diary

Nowt wrong with 10mm HDPE wheel protection!

Looking forward to this, man. Will be interesting to see how those motors perform at 3:1. I know virtually nothing about gold motors, only that the 12v model doesn't exist now? They must be low RPM if 3:1 doesn't result in silly speeds.

As for HDPE for spinner bulkheads, is nylon really that superior? Why? It's somewhat stiffer, but also more brittle, for the high speed stresses of spinner mounts is the slight give in HDPE that undesirable?

Perhaps I'm a little bias, our negative experience with brittle plastic is a little more developed than some ( ), though I have seen several instances of nylon cracking in combat.

[maddox10]

Re: Team Invade's Build Diary

I don't understand the bias against 10mm HDPE.

It seems that after 11 years of roboteering, and using HDPE as armor, I'm still happy with it.

The only failure we had, was against Kan-Opener, and that was with Obsidian.
And the damage there that doomed the machine, was the buckled 5mm 6082 ali baseplate and crumbled drive.

[mattsdragons]

Re: Team Invade's Build Diary

Inertia XL uses HDPE bulkheads for the disk, works pretty well it would appear

[daliad100]

Re: Team Invade's Build Diary

Nylon is significantly stronger and deforms much less before breaking than hdpe.
Good for critical structural components (disc mounts etc.) possibly less good for armour depending on how it's used/ what it's up against.

[Bodge Job]

Re: Team Invade's Build Diary

Yeah I agree, nylon is a lot sturdier, you can feel the difference when you work with it. The only problem I have found with nylon is that it becomes more brittle when it's cold, so you have to be more cautious when machining it outside in winter. But luckily you don't fight them out side, so it's fine.

[Team Invade]

Re: Team Invade's Build Diary

One wheel pod finished





I've cut down the HDPE and axle, and countersunk the screws for the motor so the belt doesn't catch on them. Now that I'm using screws that aren't too long the belt feels a lot tighter, which is good. The whole setup weighs about 1.75kg, which I think is quite good considering that there's 875g of motor and 20mm thick HDPE in it.

I've decided on using Nylon for the spinner bulkheads. I do think that HDPE would probably just about manage but it's always better to be certain. I think the drive ratio should be fine. The motors are 24v and I'm only going to be running them on 5 cell, and I did a quick test and the speed seemed fine.

[Team Invade]

Re: Team Invade's Build Diary

Started the second one



...amongst all the HDPE sawdust

Not got a second set of pulleys yet so that'll have to wait.

[Merkabah_PT]

Re: Team Invade's Build Diary

Looking good.
Reminds me of these:http://www.robotmarketplace.com/prod...K-BKTMODA.html

[Team Invade]

Re: Team Invade's Build Diary

More progress.



Joined the two side pods with more pieces of 20mm HDPE. Quite wide at 48.6mm but it's still pretty small, hopefully the width will help to counteract the gyro effect. Just over 4kg so far, looks like it's going to be tight on weight.

I'm just about to start the central bulkheads which will be 22mm nylon.

On another note, our three existing robots with a nice new paint job before they got scratched at Telford on Saturday:

[Team Invade]

Re: Team Invade's Build Diary



Cut the bulkheads out of 22mm nylon, each weigh approximately 1kg. I had to drill holes around the curvy bits to cut them out. I have to say they do feel a lot tougher than HDPE, harder to work with though! They could still do with a bit of filing to neaten them up, but that's not essential. I'll do that when finished if it's done with any time to spare.



I've mounted the two bulkheads to the two bits of HDPE. They'll also be screwed to the back but I can't do that until I've got the brushless mounted. At this point it weighs roughly 6.2kg.



The disc in place. Still need to attach the pulleys and bearings to the shaft. The disc weighs approximately 2kg so I'm guessing it's around 8.4kg now, but I haven't checked yet. I'd say it's likely to be around 12.kg to 12.5kg all finished without any Hardox armour. Pretty certain that it's going to weigh the full 13.6kg now!

[Ellis]

Re: Team Invade's Build Diary

Looking really really good!