20-12-2004 22:25

Arefin Bari

Re: pic: Messing around

Great job Pat. Very simple and effective transmission. ...

whats the ratio? how much would it weigh?

::goes and steals ideas::

20-12-2004 22:40

Ryan Foley

Re: pic: Messing around

First of all, good work so far. I do have a suggestion how ever. You may want to consider enlarging the outside plate (closer to the sprocket). This does 3 things:
1) you can support the motor output axles in 2 places
2) you can move the cross beams higher, above where the motors mount, to help strengthen the motor mount plate
3) makes machining easier, as you could make the same plate twice rather than making 2 different ones.

Again, good work so far, and congrats on posting your first gearbox on CD, that takes some courage to do.

20-12-2004 22:57

sanddrag

Re: pic: Messing around

In your design, I would make the small gears smaller and the big gears bigger. This will give your output a lower speed and higher torque and you will not have to have as much of a chain reduction aftwerward. You might even be able to couple it right to a wheel (depending on what size the wheel is).

20-12-2004 23:05

Specialagentjim

Re: pic: Messing around

Side Plate
One thought is on the plate where the sprocket is. Trying to remove that plate in the heat of competition from the robot would be especially difficult with the holes for the screws to mount to the frame where they are (imagine trying to get a screwdriver down there during finals when a gear shears). Flip the plate around and have the frame mounting screws on the outside.

Motor Position
Its a bit scary to see the motor so high on a thin piece of metal sticking up without any support. A solid whack from a random robot or team member and that could potentially bend just out of interfacing with the gear. Possibly consider moving the motors lower in the design and centralizing it between cross supports (I think this may have been touched on earlier).

20-12-2004 23:07

Greg Perkins

Re: pic: Messing around

Hey Pat,

Excellent Job man,

I agree with Foley, I'd make that outerplate taller and support your motor shafts..and/or not put your gears so far out onto the motor's shafts.... set up a CNC mill/ or a prototrac and you could bust out enough of one plate...instead of many different plates...

I try and work and use a mirrored set of plates...it makes machining numerous times easier...

but great work mr. patty

20-12-2004 23:34

JVN

Re: pic: Messing around

Pat,
As far as the gearing goes:
I'm positive you don't need 2 stages for 8 fps from a 5500 RPM output motor.

Try dropping it to one stage, and utilizing a much larger initial reduction.
With a large single stage gear reduction, you should be able to get a nice sprocket reduction which scales to any wheel size (ie: 10:20 for a 4" Wheel, 10:30, for a 6" Wheel, 10:40, for an 8" Wheel, etc).

I'm in love with 10 tooth output sprockets for exactly this reason. It allows for a larger chain reduction (by sacrificing chain wrap, I know...)
Also, #35 - 10 tooths come with a TON of bore sizes.

John

20-12-2004 23:45

Matt Adams

Re: pic: Messing around

* *			 
* *			  
* o o o o o o o o o o o o  
* o o o o o o o o o o o o   

*'s - walls with ledge notch cut in them.
o's - wall that fits on ledge.

21-12-2004 06:27

Cory

Re: pic: Messing around

Those plates are going to be hell to manufacture. You're going to need CNC machine tools to do so.

Consider making all rounded/angled surfaces 90* angles and you could do it manually. Also, the right side plate is going to be REAL hard to make, seeing as you're going to have to start out with a solide aluminum block and mill it down so that it's got the angle on the bottom, unless such a material is already sold that I'm not aware of.

21-12-2004 06:51

NoodleKnight

Re: pic: Messing around

maybe he can leave some extra material and pound out a 90* flange

21-12-2004 08:39

Andy Brockway

Re: pic: Messing around

This is nice compact design.

As far as supporting the motor shafts..... Place the gears as close to the plates as possible and no support is needed for the cim. The andymark reducer should not need support either based on how they are using it in their gearbox.

In fact, place all gears as close to the plates as possible to reduce deflection. As for your plates, it may be tough to find angle material that doesn't require that most is cut off on the short leg. If you have a source, I am interested. I have stayed with 1/4" on my main plates and my latest design has the motors up high like yours.

The nice thing about Inventor is it lets you draw anything, the next step is to think like a machinist and decide if pretty or functional is more important. We perform weight loss on our plates with the bandsaw and drill press after the gearbox is proven functional.

The season is almost here, I hope everyone has built something by now. The last thing we all want is robots that do not move on the field!

21-12-2004 09:52

dlavery

Re: pic: Messing around