14-01-2015 22:39

s_forbes

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Nifty! I like the single reduction and the angled module approach you're taking. Needs more Shellac. And mind that ground clearance.

I'm also really jealous of your laser cutter... that's got to be one of the most useful tools you could have for a 6 week build season.

14-01-2015 22:50

asid61

Re: pic: Bit Buckets 2015 Prototype Drive Pod

+1 on the laser cutter. How long does it even take you to cut out your chassis? It's crazy how fast you guys can get stuff done with that thing.

14-01-2015 23:21

z_beeblebrox

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Our off-season chassis took about 4 hours of laser time, including setup. This module took 9 minutes.

It's a pretty neat tool to have; we can make 2D parts faster than literally any other team.

Edit: At least as fast as any other team.

14-01-2015 23:23

orangemoore

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Well, that is assuming no one else has access to a laser cutter.
Cough Cough

14-01-2015 23:26

MrForbes

Re: pic: Bit Buckets 2015 Prototype Drive Pod

we just have to assume that no one else does, because we only see 4183 posting pics of all these neat parts



.

14-01-2015 23:30

kuraikou

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Honestly because we have one now working without one would be extremely hard, if you have a lot of extra money (ha a first team with extra money) I suggest getting one, they are useful in most situations and cut time in design, fabrication, and programming by quite a bit.

14-01-2015 23:33

craigboez

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Thats a neat looking encoder. Do you have any experience with it that you can share?

14-01-2015 23:38

z_beeblebrox

Re: pic: Bit Buckets 2015 Prototype Drive Pod

This year is our first time using them, but there's some information here.

This is the model we're using; I believe they're also available in FIRST Choice.

15-01-2015 00:37

Lone Wolf

Re: pic: Bit Buckets 2015 Prototype Drive Pod

1899 makes almost fully-wood robots every year.

15-01-2015 01:27

asid61

Re: pic: Bit Buckets 2015 Prototype Drive Pod

That kind of speed makes me want to abandon our bridgeport and buy a laser cutter.
But the team probably wouldn't have the heart.

15-01-2015 01:28

AdamHeard

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Why geared so fast?

Why not both? Never give up the mill....

15-01-2015 01:39

asid61

Re: pic: Bit Buckets 2015 Prototype Drive Pod

I would take the mill home.
We might get rid of our old Grizzly lathe in favor of something that can actually cut steel in a few months, so a hobby machine might be coming my way already...

15-01-2015 01:53

Amar Shah

Re: pic: Bit Buckets 2015 Prototype Drive Pod

I remember reading your laser cutter is 29x17", but how powerful is it?

15-01-2015 08:40

z_beeblebrox

Re: pic: Bit Buckets 2015 Prototype Drive Pod

We're using Killough drive, so robot speed is 1/sqrt(2) wheel speed. We also like the simplicity of a single reduction gearbox.

I'm not certain; I think 60 or 75 W.

15-01-2015 09:31

JamesCH95

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Neat drive module. I like the single reduction, very simple. What sort of fasteners are you using to tie everything together?

Does a 4'x8' CNC plasma cutter count? Each of these parts took 4-5 minutes of cut time (1/4in 6061 T6), and that long cut time is due to the dozens of pierces for the lightening pattern.

http://i.imgur.com/QCryxlE.jpg

https://www.youtube.com/watch?v=2HHVwJ_C31M

The side-panels took less than 2 min each to cut from 0.032 5052 Al.

http://i.imgur.com/gU6AhRa.jpg

Or a 4'x4' CNC router? All of these parts together took about 17min of cut time, most of which was in the pocketing.

http://i.imgur.com/FgtZxiL.jpg

15-01-2015 10:42

Bruceb

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Exactly what wood are you burning with your laser. I say exactly because I have access to a 160 watt laser and have tried cutting 1/4 Baltic birch and if it will cut depends on where I get it.
Some cuts real nice and some will only seem to cut to the glue line then just starts burning. So, if you have any details on what you are using it would be appreciated.
Thanks

15-01-2015 10:47

AdamHeard

Re: pic: Bit Buckets 2015 Prototype Drive Pod

I think a killough actually has a root2 speed up.

15-01-2015 12:14

s_forbes

Re: pic: Bit Buckets 2015 Prototype Drive Pod

I hadn't put much thought into it, but I believe you are correct. Those modules will probably need another reduction stage.

15-01-2015 13:20

Amar Shah

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Some plywoods have glues or fillers that don't cut well, which would explain it. 160W is otherwise overkill for 1/4" plywood.

15-01-2015 13:40

Bruceb

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Yes it will cut an inch of pine but not some plywoods.

15-01-2015 14:06

z_beeblebrox

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Likely true. I'll look into it today.

.25" 5-ply Baltic Birch plyood from Woodworkers Source.

15-01-2015 23:27

z_beeblebrox

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Version 2, ready to be cut tomorrow. Two stages of reduction, for an adjusted robot speed of ~10 fps. Adding a reduction stage only made it ~.25" longer and wider.



Our mostly complete chassis. This will also (hopefully) be cut out tomorrow.

15-01-2015 23:44

BHS_STopping

Re: pic: Bit Buckets 2015 Prototype Drive Pod

I'm just taking the conservation of energy route.

Assume constant power output P. P = force * velocity (dot product used here). Since the force of the wheel along the direction of motion is effectively reduced by a factor of 1/sqrt(2), the velocity must increase by a factor of sqrt(2) to maintain that power output.

16-01-2015 01:36

Dunngeon

Re: pic: Bit Buckets 2015 Prototype Drive Pod

What settings does your team use for the cut? I just realized we have a 60W 30x15 laser cutter sitting in the other room at school.

16-01-2015 08:44

z_beeblebrox

Re: pic: Bit Buckets 2015 Prototype Drive Pod

I'm not sure; the settings for our laser aren't "real" units like Watts or Inches/ second. I'd suggest you just try different settings until you find something that works. But do try it; the laser is an amazing resource to have available.

16-01-2015 08:55

orangemoore

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Most laser cutters are different. If you want know the setting you can figure them out. But a good starting point is the internet and research into the laser cutter you have.

16-01-2015 11:38

Dunngeon

Re: pic: Bit Buckets 2015 Prototype Drive Pod

Definitely, I wasn't trying to just copy paste settings. That rarely works in my experience. I was curious about the speeds you're able to go. Although if the laser doesn't use real units that's disapointing .