[BW] GR-01 Build Diary

[Giles]

More cad doodling. A lot of stuff to figure out with the weapon and chassis still, but I'm starting to like this design. At the moment its using 10 toothed HTD3 pulleys, I've found these in 10mm belt thickness, wondering if 5mm can be obtained somewhere? I've used 5mm ones in the CAD drawing on the secondary wheel drives, but I'm not sure if they exist, couldn't find any myself.

[Ellis]

Looking really good. I use http://www.beltingonline.com/ for all things transmission, they have standard HTD widths but can also cut to any width you want.

[Giles]

Cheers Ellis!
More cad work. I'm about ready to ditch 123D Design and move everything into inventor. Getting frustrated with the limited amount of tools now (especially when wanting to make belts).

Heres a lil more rough design work. Moved the belts inside the frame for safer housing and more compact walls, moved the motors back to directly drive the rear wheels and thought a bit more about the drum mounting. Hopefully when I get everything into Inventor I'll be able to solve design issues faster.

[Mouldy]

like it!

[Max]

Design looks awesome!

If you are limited in terms of manufacturing capabilities you could easily get those side panels laser cut by a company like laser-master depending on material.

[suvv]

this looks outstanding a other good option for wheels is the finger tech foam wheels they are insanely grippy and very durable especially if your going to have exposed wheels im looking forward to sing this come to life

[Eventorizon]

That looks mental! I love it! Just make sure it cant get stuck on its side

[overkill]

The CAD looks great but there are some improvements you can make:

The pyramid shape looks cool but it raises the drum off the floor, this prevents the drum from hitting low hight bots and wedges will be able to get under your bot from all directions. If you use a shape like this, the drum will be far more effective:



This also gives the bot a wedge as a secondary weapon and makes the bot harder to attack from the rear.

Another possible issue is the small pulleys driving the wheels. Because the belt is driving three wheels in a triangular pattern, it will not be engaging many teeth in the pulleys and might slip or rip teeth off the belt. you could make the pulleys larger or add an adjustable idler wheel to make sure there is plenty of tension on the belt. Having an adjustable idler also makes assembling the bot much easier as you can put the belt on while its slack. In the design above, you could run the belt like this:

[RogueTwoRobots]

While adding the idler is a good idea, wrapping a toothed timing belt backwards over the motor pulley isn't so much

But I'd agree with reducing the height of the robot to bring the drum closer to the floor. It does look like the teeth would be quite far from the ground otherwise, and most of the current crop of beetles have a rather low profile. Great design and research work so far though!

[overkill]

Doh, what was I thinking? Double sided timing belt, perhaps?

[Eventorizon]

Doh, what was I thinking? Double sided timing belt, perhaps?

I've been looking into those for ages (that design is getting to look an awful like Conker 4, and its his first try!) But they are very expensive and I've never found anything that could go in a Beetle sized robot. I am sure they are out there but they are proving damn difficult to find.

[harry hills]

If you go for HTD5 then double sided belts start at £2.

[Giles]

Thanks for the suggestion! I gave it a try during my lunch break to see how it might look in 3D.

My main concern with the wedge is that it needs to be very close to the ground to be effective. To ensure this works nicely when inverted, i've added a hinged wedge tip to it, so that when the robot flips, the tip of the wedge is always brushing along the arena surface.



What do you think? Wedge tip bad or good idea? Might be more hassle than its worth?

[harry hills]

More hassle than its worth in my book. Also it really doesn't look as good with the larger drum. I also think it needs to be a smidge wider too.

[Eventorizon]

Yeah, but not in a length you can actually use in a beetle, minimum length I have found is 565mm: http://www.beltingonline.com/5mm-dou...ing-belts-4574