[BW] GR-01 Build Diary

[Giles]

@Brandon - Yep, scoop on the front will be on its way soon!

@Overkill - Egg beater it is then!

More cad work today!

Figuring out the drive system. Pretty happy with it so far.



The blue parts are spacers to help add support to the framework without the need for more threaded rod/bolts.

All of the wheels will be 3D printed to include the pulleys in one single piece. I will be insetting bearings into these by pausing the print half way, inserting the bearings and then resuming the print.

The idler pulleys will be 3D printed also. Because I have complete control over their diameter with 3D printing, I will be able to adjust them to give the perfect amount of belt tension (hopefully!).

The motors are counter sunk into the alu frame and will be held in place with a 1mm or 2mm front plate.

I've changed the material of the outer wall to use HDPE and I have also cut out the majority of the material from the inner piece, making them 86 grams instead of 200!

THINGS TO DO:

Firm up the weapon bulkheads - I'll probably add a set of bolts either side of the shaft and another plastic spacer between the two walls either side.

Add scoop - Design and integrate some form of scoop. Probably a similar idea to the mini flip out ones I printed out as a test. This will help to push opponents up into the spinning weapon.

Add weapon motor mountings and belts - Need to think about how this will work. Thinking of using two o-ring style belts for it.

Housings/shock absorbers for electronics - Thinking of putting these inside a little box which is shock mounted onto the frame. Hopefully this will take some of the stress away from the electronics.

Design an egg beater style weapon - Replacing the drum design with an egg beater.

For all of the 3D printing I will be using two types of filament.
The first one is Taulman 910 Alloy. This stuff is STRONG. I'll be posting some strength tests of the stuff when the new spool arrives next week. They have some stats on the website for it here: http://www.taulman3d.com/910-features.html I'm hoping it will be a nice light yet strong alternative.
The second filament I will be using is called Ninjaflex. Its a rubbery filament that can stretch and bend. With a durometer of 85A it seems perfect for tires and shock mounting things. I'll be playing around with different uses for this stuff a lot. One idea is to make little pouches to put the ETC's/receiver inside of.

[harry hills]

You're so legit it hurts slightly. Great work fam.

[overkill]

I don't think the 3D printed wheels will last long - all the 3D printed antweights that I have seen broke after a few fights, including nylon ones printed on pro machines by Shapeways. Give it a go, but also think of a plan B just in case.

Making printed carriers for electronics works very well, I haven't had anything die from shock damage in several years.

I'm guessing that the blue spacers are plastic. Would it be possible to replace them with a custom sized aluminium nutstrip? That would save space internally and provide a much stronger attachment between the outside bulkheads and the rest of the frame.

[Shakey]

I don't know how they've been 3D printing antweights Nick but all I can say is that it's wrong if they are dying in a few hits. If you do it right they can be EXTREMELY strong. Nylon prints being some of the strongest of the lot.

[psycho_fling]

The ability of a 3D printed part to survive in a robot is down to a number of factors. Material, printing technology, the way in which the model was printed, layer thickness etc and the design of the part in the first place.

For your wheels are you making the tyres and hubs separate or in the same build? Which printer do you use btw?

Great designs

[GlenR]

The 3d printed ones were almost universally ruined after a fight with a spinner, I can't recall any being made from it in the last event we had, but then again its an enclosed arena so the robots don't shoot out after the first hit :P

Thats a sweet design too, Looking foward to seeing it running. The forks are especially cool!

[typhoon_driver]

Taulman may be ok but you need to watch what the orientation of the weak bonded layers is in relation to the most likely stress.

[Giles]

Thanks for the replies all! My shipment of filaments arrived today, so I'll be testing out the feasibility of it all over the next few days. In my experience with 3D printing, this stuff should be up to the job, but we'll see!

I just realised that since swapping the side panels from being aluminium to HDPE, I can no longer get them laser cut. Does anybody know of a good CNC service that can work with HDPE? Or perhaps another option?

[shakesc]

HDPE cuts nicely with standard woodworking tools - just have a steady hand
I use either a chop saw or a circular saw and fence

[RogueTwoRobots]

A jigsaw with a woodcutting blade works great for HDPE, especially in the smaller thicknesses. It will go through thinner stuff like a hot knife through butter though, which makes it quite easy to end up with wavy lines as opposed to nice clean straight ones, so if you do opt for that method, a steady hand as Chris mentioned, or even just taking it slowly, will prevent that.