pic: Chassis Idea

[Rion Atkinson]

Originally Posted by Akash Rastogi

Looks good.

I'm wondering...did you want the wheels on dead axles or live?

(Starts editing the OP.)

The wheels are on live axles. Sorry about that.

-Rion

[Akash Rastogi]

Hopefully someone with more experience with 6wd can post here (I've never built a live axle system before) but what is the purpose of having a live axle system? To my understanding, the occasion when you use a live system is when the gearbox is directly driving either the center wheel (live) or a corner wheel but then the other two wheels are on dead axles.

Someone want to clarify this for me?

[Madison]

Originally Posted by Akash Rastogi

Hopefully someone with more experience with 6wd can post here (I've never built a live axle system before) but what is the purpose of having a live axle system? To my understanding, the occasion when you use a live system is when the gearbox is directly driving either the center wheel (live) or a corner wheel but then the other two wheels are on dead axles.

Someone want to clarify this for me?

As far as I can tell, there is no particularly compelling reason for this to use live axles.

[Akash Rastogi]

Originally Posted by Madison

As far as I can tell, there is no particularly compelling reason for this to use live axles.

I meant to ask the question in general too. Is there less loss of power when using live axles or something? What is the benefit, if any?

[Brandon Holley]

Originally Posted by Akash Rastogi

I meant to ask the question in general too. Is there less loss of power when using live axles or something? What is the benefit, if any?

The benefit of live axles comes from being able to use the axle as the transmission of power to the wheel. As opposed to bolting the sprocket directly to the wheel and placing bearings in the wheel, the live axle setup transmits power from the sprocket through the axle to the wheel.

Some setups may only function with a live axle setup. However given the choice between dead or live axle....I use dead axle wherever and whenever I can.

Art- If your supporting the shaft on both sides anyways (assuming a wheel your using can have a bolt pattern), then bolting each end of the shaft in place is even more simple IMO, instead of having to turn down the ends of the shafts.

-Brando

[artdutra04]

Originally Posted by Brandon Holley

Art- If your supporting the shaft on both sides anyways (assuming a wheel your using can have a bolt pattern), then bolting each end of the shaft in place is even more simple IMO, instead of having to turn down the ends of the shafts.

Turning down the ends of shafts on a lathe takes one tool.

Drilling and tapping the ends takes three: a center drill, the drill bit, then the tap.

On a manual lathe, it's faster to turn the ends down.

[Jared Russell]

I will sum up my experiences with live and dead axles below.

Live axles are useful because:

• You can drive them from any point on the shaft (e.g. West Coast Drive where there is a bearing block between the driving sprocket and the wheel).
• The keyed/hex shaft becomes a "universal" interface for attaching wheels, bearings, sprockets, gears, brakes, encoders, etc. As long as your piece has an (ex.) 1/2" keyed bore, it will rotate along with everything else on the shaft. With a dead axle, you must attach pieces to each other directly, and not all wheel and sprocket combinations play nice in this regard.

Dead axles are useful because:

• You are minimizing the rotational mass of the wheel assembly and therefore maximizing efficiency since the shaft itself doesn't need to spin. Unless you have a truly massive axle or bad bearings/alignment, however, we're probably not talking a huge difference.
• In the cantilevered case, you are minimizing torsional loads on ball bearings with dead axles (since the bearings are still centered on the axis of rotation no matter what the deflection of the shaft).
• The closer together two bearings are, the easier it is to have them stay aligned. In a dead axle setup with two bearings in a single wheel, alignment is trivial. Live axle systems that support both ends of the shaft can get out of alignment more easily.

Did I miss anything?

[JVN]

Originally Posted by Jared341

Dead axles are useful because:

• You are minimizing the rotational mass of the wheel assembly and therefore maximizing efficiency since the shaft itself doesn't need to spin. Unless you have a truly massive axle or bad bearings/alignment, however, we're probably not talking a huge difference.
• In the cantilevered case, you are minimizing torsional loads on ball bearings with dead axles (since the bearings are still centered on the axis of rotation no matter what the deflection of the shaft).
• The closer together two bearings are, the easier it is to have them stay aligned. In a dead axle setup with two bearings in a single wheel, alignment is trivial. Live axle systems that support both ends of the shaft can get out of alignment more easily.

Did I miss anything?

We also use dead axles as structural members of our chassis (a round axle with tapped ends = chassis standoff.)

If you get creative with your axle placement and the structural design of your chassis this can eliminate the need for other structure and result in a lighter overall system.

-John

[Brandon Holley]

Originally Posted by artdutra04

Turning down the ends of shafts on a lathe takes one tool.

Drilling and tapping the ends takes three: a center drill, the drill bit, then the tap.

On a manual lathe, it's faster to turn the ends down.

# of tools is kind of an unfair comparison here. Drilling the ends of a piece of stock is probably the simplest operation you can do on a manual lathe. No zeroing (assuming your going to just do a rough estimate of depth because your tapping the hole anyway) and no measuring of the piece to ensure correct diameter.

My guess is that the lathe operations would take close to the same amount of time for both kinds of axle, including the tool change for the drill. The tapping will cause the dead axle to take a longer amount of time, but we're talking about a matter of minutes which I do not feel is enough to justify changing a design from dead to live. There are a ton of other considerations obviously, but I just wanted to point that out.

-Brando

[IndySam]

Nice looking CAD.

We have done similar box chassis in the past and depending on the game we will more than likely do one again this year.. They are strong, simple and very reliable but heavy.

You can replace the shaft supports with simple aluminum blocks and make chain tensioning and changing wheel drop easier.

You can also loose the entire upper structure or wait and make one that is more game appropriate out of lighter stock.

We don't use welding anymore. Instead we glue everything together. Never had a failure.

[IKE]

Originally Posted by IndySam

We don't use welding anymore. Instead we glue everything together. Never had a failure.

I would love to hear more about this.

[IndySam]

Originally Posted by IKE

I would love to hear more about this.

We machine connectors (like 8020 quick frame) that slip inside the 1" square tube and then use Loctite Hysol to bond them together.

You can hit it with a sledge hammer and the aluminum will give way before the Hysol does.

[Creator Mat]

for dead axles we just use 1/2" bolts. We find them to be easy to take on and off because all they need to be attached is nut. Yes you do give up some weight and room with the added material but we feel that the simplicity makes up for it.

[gburlison]

Originally Posted by IndySam

We machine connectors (like 8020 quick frame) that slip inside the 1" square tube and then use Loctite Hysol to bond them together.

You can hit it with a sledge hammer and the aluminum will give way before the Hysol does.

Which Hysol formulation do you use? Epoxy, Urethane, or Polyurethane? Any other information about how you bond the aluminum frame together would be appreciated.

[Trent B]

IndySam I am with gburlison in that I would love to hear more about this. I never thought of gluing a frame together but that may be a good alternative to welding as we have a sponsor who could get us the 8020 parts easily enough (if we can't make our own) Do you have any examples of possibly a 2x1 tube connector? If you don't I would still love to see what your 1x1's look like.

Thanks,

Trent B

About the CAD Model, interesting choice of live axles but I suppose the wheel was the deciding factor.

I found too when I did some of my own CAD models, for things like batteries, cims and gearboxes its usually easiest just to set the weight and be done with it (no messing around with materials, but always use them on stuff you plan to build yourself (aluminum frame)).

I have yet to design a frame like this, might try to CAD one quick before the kickoff.