Designing my 4wd belt drive 3lb beetle weight

Cody wrote:

shim it with tooth picks till you get the right tension

I did that once.

can this design work with a beater bar? regardless of the type the bolt used has to take up space in its width (when turned sideways in other words the Y coordinate), so is it practical to use this design with a beater bar since their diameter spinning far outreaches the height of the robot?

Ctown_ftw wrote:

Cody wrote:

shim it with tooth picks till you get the right tension

I did that once.

lol i've used tooth picks as shims more then once

stay on task!....and id use a Swiss army knife toothpick, after all the Germans made Sham-wow and they build good stuff (thanks Vince), and the Swiss don't worry about war, so they can concentrate on making mean toothpicks

Missed the beater question, you have always used an adjustable motor mount to adjust tension rather then the weapon shaft.

kind of obvious, but adjustable weapon shaft sounds like a bad idea.

rjw wrote:

kind of obvious, but adjustable weapon shaft sounds like a bad idea.

Not what we were talking about, but I think there could be a few ways to make an adjustable weapon shaft work. It would be most practical in order to use interchangeable weapons.

you could probably do it similar to how the back tire on a dirtbike is mounted and have adjustable screws to adjust tension and a threaded axle that bolts where you want it.
I wouldnt want to do it though

as for the weapon shaft, its an overly complicated idea. interchangeable weapons would be much easier if u designed the different weapons around the shaft.

however the "dirk bike tire axle" is something we looked into today, and will most likely appear in the new bot. so thanks to everyone who talked about this and helped explain it. it completely gave us a boost because we were stuck on how to mount a front dead shaft that would be secure enough to take a strait hit

Brandon Roberts wrote:

as for the weapon shaft, its an overly complicated idea. interchangeable weapons would be much easier if u designed the different weapons around the shaft.

however the "dirk bike tire axle" is something we looked into today, and will most likely appear in the new bot. so thanks to everyone who talked about this and helped explain it. it completely gave us a boost because we were stuck on how to mount a front dead shaft that would be secure enough to take a strait hit

A hole in each frame rail wouldnt work?! lol

edit: cause i don't proof read

Quote :

A whole on each frame rail wouldnt work?! lol

Don't mind him.

we were sketchy on the idea =p, and cut me some slack this essay fried my brain ( James -.-)

Brandon Roberts wrote:

we were sketchy on the idea =p, and cut me some slack this essay fried my brain ( James -.-)

ha i was going to call you a nerd for doing homework on a friday and then I realized that its not friday and I've completely lost track of the days since all I've done is work over break ha

i thought today was Monday until like 4pm when i went into work, felt pretty special being that its not Monday and being so i am not on the schedule

I was over in Torgr-Beetleweight blog asking about the UHMW I figure that I will continue any question back here.
It's no longer going to be belt driven, does anyone know of a free prototyping program to make a better design instead of just drawling on paper?

I think 3/8 thick UHMW for the sidewalls of my 3lb.

If I was going to use it as the bottom or top plate what thickness would you use?

4goodbuys2 wrote:

I was over in Torgr-Beetleweight blog asking about the UHMW I figure that I will continue any question back here.
It's no longer going to be belt driven, does anyone know of a free prototyping program to make a better design instead of just drawling on paper?

I think 3/8 thick UHMW for the sidewalls of my 3lb.

If I was going to use it as the bottom or top plate what thickness would you use?

So now its back to being a beetleweight?

It's back to being a beetleweight for the following reasons.
1 I now know about uhmw polyethylene, so I'm not using alum angle anymore.

2 I ordered 4 turnigy 20 amp brushed esc's $5 each for the drive, all 4 will weigh 2.4 ounces.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9090

I'm going to make a beetle and a ant it's just a matter of which one comes first.

well Google sketch Up is free, its more of a rendering program then a CAD. We use it just for that purpose of not drawing on paper. its a lot simpler to use then CAD as well so if you have no experience with any software at all give it a try.

like i said its free and 100x better then using paper. AND! you be saving the rain forests! =p


if you are still a student in school (never checked your introduction sorry =p) autocad offers a free program to get a student version, there are two threads on that though.

The threads i know off hand are:
" Solidworks Student"
" Free Student Versions of SolidWorks/AutoCAD" (in Tech Help)

I have had limited experience with Google Sketchup, but some folks think it's an OK tool for getting the rough idea together. It seems to be a pretty "quick learn", with several video tutorials.

In a similar way, I first got my feet wet with CAD by using a free online utility called emachineshop. What's good about emachineshop is that it gets you thinking in the correct way to move to full scale CAD (The process and interface are somewhat like solidworks or autocad), it has (or at least had, back when I was using it 4 years or so ago) a really good set of video tutorials, and it's free. What REALLY sucked about it was the inability to do assemblies. Each part was a separate entity and there was no way to put them together on-screen. I imagine that Sketchup has similar limitations, but I really don't know.

It can't hurt to take a look at both, if you are looking for FREE stuff.

This is the design that I came up with for my lifting beetle-weight after a few variations.
I haven't thought of the exact dimensions yet but I want close to 10-12 inch's in width so I can get other bots into the lifter.

I'm going to have 4 gear-motors to power the wheels I was looking at these http://banebots.com/pc/MS-25XXX-180/MS-25010-180 but they are discontinued so I will have to find something similar.

For now I will use 4 - 20 amp brushed single channel esc's for the drive so I'm looking for some gear-motors like the discontinued banebot motors to take advantage of the extra amps.

The lifter is most likely going to be powered by a low rpm gear-motor I have a design in my head for that but I haven't put it on paper yet.

Let me know what you think of my design so far and if there are place's that I can improve.

EDIT I think I just found a better solution and it's also cheaper I could by 2 of these 1000rpm
ebay gear-motors and belt drive it to the front or I could just buy 4. They look similar to the b16's.
Does anyone have any experience with these motors? http://cgi.ebay.com/Two-Mini-12V-DC-Gear-Motors-1000rpm-Hobby-buySAFE-/250673405483?pt=LH_DefaultDomain_0&hash=item3a5d4c9e2b
I also found this one http://cgi.ebay.com/One-Medium-Torque-DC-3V-420RPM-Gear-Motor-Multi-Purpose-/300512533116?pt=LH_DefaultDomain_0&hash=item45f7f15a7c

did look at them but there probably the same ones a couple guys are using

Which gear-motors and what combination do you thick I should use?
4 of these motors 1 on each wheel over-volted to I'm not sure how many volts?
http://cgi.ebay.com/One-Medium-Torque-DC-3V-420RPM-Gear-Motor-Multi-Purpose-/300512533116?pt=LH_DefaultDomain_0&hash=item45f7f15a7c


Or 2 of these gear-motors in back with belt drive to the front, but I'm not sure if there is enough room on the shaft to add a motor and a pulley?
http://cgi.ebay.com/Two-Mini-12V-DC-Gear-Motors-1000rpm-Hobby-buySAFE-/250673405483?pt=LH_DefaultDomain_0&hash=item3a5d4c9e2b



I'm kind of leaning towards the 3v gear-motor over volted to 7.4 or 11.1, but I wonder if if would have the same power as 2 of the other gear-motors, and I wonder how much each one of the 3v weigh.

I am NOT speaking from direct experience with any of those motors, but overvolting a 3V motor to 11.1V just sounds like a fire waiting to happen.

I'm exaggerating, of course, but I don't see that motor lasting long. My general rule is overvolt no more than 50% (3V to 4.5V, 12V to 18V, etc).

I received my UHMW polyurethane yesterday in the 3/8 thick and the 1/8 thick, I think I may of ordered it a little thick I guess I will have to make my robot thinner to make up for the extra weight.
I think I may go with the 12v 1000 rpm gear-motors unless someone has a better solution.

I have no experience with those 1000rpm motors, but I do use these:

http://cgi.ebay.com/2-x-12V-DC-1000RPM-Mini-Torque-Gear-Box-Motor-Hobby-/320569452140?pt=LH_DefaultDomain_0&hash=item4aa36da66c

The ones you listed appear to have longer, heavier motors on them, and their torque is listed as lower, but I don't know how much to read into that because the listed torque on them both is much less than they can produce.

From my experience with mine I am happy with them. The motors are a bit weak for their size, but the gearbox seems very robust, I've had wheels ripped off without damaging the gearbox.