Designing Custom Gearbox's

[Eventorizon]

Are there any basic hints and tips to designing custom gearboxes?

I was planning a 2 stage reduction of 3:1 - 3:1 with the Technobots MOD1 gears, 12 tooth and 36 tooth.

Will I need bearings, how big should the walls be, do you bolt the gearbox together, how can you save weight etc

I am guessing you aught to have this kind of thing CNC'd so if there is any companies or people who will accept a solidworks file let me know

Thanks in advance

[psycho_fling]

Re: Designing Custom Gearbox's

make sure you use decent shafts bearings are a must or bushings depending on a few things

it will probably make things easier if the gear boxes can be assembled outside of the robot so bolting together will help (just make sure the bolts and supports aren't going to get in the way)

ali is probably your best bet and you could also use say 10mm which has been pocketed (other people will advise better on thickness)

and alot of companies use solidworks or accept the many file types you can save your model as

hope this helps

[blazerbotics]

Re: Designing Custom Gearbox's

Its going to be expensive to have them made if you dont have access to a lathe or mill yourself.

[Eventorizon]

Re: Designing Custom Gearbox's

The technician at my university will do it if I ask nicely. They will do it when they have time so as long as I give them it long before I actually need them then I can get almost anything made.

What would people say to having them milled from blocks of nylon rather than Alu so that I don't have to worry about bearings, or could you make them from nylon and put the bearings in anyway?

[maddox10]

Re: Designing Custom Gearbox's

Depending on application, but I have good experience with steel as main gearboxplates.

Has to do with my preference for dead-axles.

Fairly simple too. I calculate gearratio, talk to the right people, and get a set of lasercut 5mm thick steel plates at the front door.
Get the right gears from my suppliers (Technobots is one), adapt them to bushing or bearing (prefer bushing, lighter and cheaper for me)
Take out the silversteel axles from my stock, grind those to length, drill and tap the right holes, turn the right spacers and start building up.

The more parts I can weld together the more I like it.

But if money allows, I prefer a ready to use motor/gearbox.
That is why I bought Gimson GR01's, and am happy with them.

[Eventorizon]

Re: Designing Custom Gearbox's

We currently use 4 GR-01's in conker and they are superb but they just cant put out the same power as the Speed 900's. Satanix runs of 2 of them and he was bashing Conker around the arena like I had no drive at all. They are just punchier and more powerful; given the right ratio.

[maddox10]

Re: Designing Custom Gearbox's

I know perfectly what gearbox Satanix 1.666 uses.

MSR 12-72 to a 130mm wheel.
Steel support plate welded in the chassis.
15mm silversteel dead axle, bolted in with M8 bolts.
Bronze 15-22-30 bushing
Single stage 6-1 gearratio. Welded on Z12 Mod1 gear on the motor, custom ali Z72 mod 1 on the wheel.
Full HDPE wheel, screwed and carpet-taped bike wheel rubber running surface.

Why do I know...

[Eventorizon]

Re: Designing Custom Gearbox's

I knew most people would know, there are few secrets in the pits

And you probably helped/did build Satanix would be my guess. But the point still stands. 4x GR01s and 2x S900 = no contest, S900's every time. Why do you think I ended up down the pit

[psycho_fling]

Re: Designing Custom Gearbox's

Mario did build them

[Mouldy]

Re: Designing Custom Gearbox's

My prefered method is machining a gearbox from a billet of aluminium, including bearings into the sections in the billet, i find steel heavy, and plastic to soft for a gearbox housing, and i prefer to have live axles. Each to there own i guess... 360's disc and gearbox are made like that, as are ploughbots drive box's, all the old whyachi stuff and a few other robots out there

Build of my selfwrighter gearbox for example; viewtopic.php?f=240&t=2810

But its totaly your preferance.

[ewan]

Re: Designing Custom Gearbox's

From seeing some of the fight videos I think the reason you were never pushing with Conker is you didn't have any wedges and the others were always getting under you, Satanix included. You could've had all the power in the world but as they were lifting your wheels off the ground it was to no effect.

[Eventorizon]

Re: Designing Custom Gearbox's

That to, but even if it was a straight shoving match I reckon Satanix would have won cos I always had the back 2 wheels on the ground when he was pushing me and yet back I went (with half the grip and torque available I know but still, poor conker)

Alu seems the best bet with live axles as I am using such a small gear (the 12 tooth). 2 Half's, bolted in each corner and then bolted to the base sheet with 4 more. Hopefully tough and rugged. I think KIS will play a large part in the design!

Thanks for the input To the Mac!

[Kenny]

Re: Designing Custom Gearbox's

It doesn't matter what motors you use, if you have a good wheel base, grip and are able to get under the other robot you will push it, also try to aim for 4wd everytime if space allows it, with 2wd the grip is always changing because the robot rocks on the centre point

[Eventorizon]

Re: Designing Custom Gearbox's

Silly question to go on the end but does anyone know the RPM/V of a speed 900?

The box says nominal 12V, but range from 6-40V. And the speed is given as 6500 rpm.

Does this mean 6500 rpm at 12V? There website is useless and stupidly I threw out the boxes thinking I would not need them again.... grrrr

If I go with what I know then on a 6 cell lipo, 22.2V, then its...

(6500/12)*22.2=12025 rpm

Am I right?

Edit: Conker does/did have 4 wheels but cos Satanix got under it was only the back 2 on the ground

[PJ-27]

Re: Designing Custom Gearbox's

To back Kenny up, I believe Cobalt uses 550 size motors on Banebots gearboxes. Only difference between them and the gimsons is the Ali gearbox housing. Cobalt also only had 2 for drive.

Just goes to show how important good weight distribution, 4wd and a ground riding wedge is.