Andymark Churros

[llamadon]

Hi, our team is prototyping a wcd this summer, and we have an excess of andymark Churro extrusion (http://www.andymark.com/product-p/am-2595.htm) and plan to use it as a live axle. Does anyone have experience using this material? If so, is it strong enough?

[orangemoore]

If you are just building a drivebase they might work.

But I have never heard it being used as an axle before and I am skeptical that it would be strong enough for the job. Most hex axles don't have a hole going all the way through it, as well as a dimple on every side of the outside edge.

If you could I would suggest you use something else.

[Michael Hill]

The churros are 6063 aluminum. Hex shaft from Vex is 7075-T6 (black anodized for superior performance, of course). I'd say there's not a chance they hold up, but that's just my speculation.

[Akash Rastogi]

I wouldn't even use regular 6061 hex shaft for this application, let alone the 6063 churros. Bad experiences with bending and snapped axles. (Just ask 2791, among others).

[s_forbes]

Excess material you say? Build it and see what it takes to break it! You will learn more by testing the churro extrusions to the limit than you will by using the "right" material from the start. If they fail, you can replace them with stronger shafts later.

I'm a big fan of destructive testing. It's fun and educational. Every now and then you find something that you were sure wouldn't survive, but ends up working and saving you time/money/weight.

[Boe]

Originally Posted by s_forbes

Excess material you say? Build it and see what it takes to break it! You will learn more by testing the churro extrusions to the limit than you will by using the "right" material from the start. If they fail, you can replace them with stronger shafts later.

I'm a big fan of destructive testing. It's fun and educational. Every now and then you find something that you were sure wouldn't survive, but ends up working and saving you time/money/weight.

I agree if you have it test it. Also since it already has the hole through it you can use that to put a bolt and washer on each end to hold the shaft in place, either by putting a bolt all the way through, or by tapping each end.

[AndreaV]

Sure, it's a 'learning experience" and you can use it, but I doubt it will last long. simple directional changes(with 120lb worth of robot) would probably be enough to twist them. The profile is probably the WORST for handling torsion loads, it's missing material from where it's needed the most for this application.

If you do use it make sure you have some solid hex(as high a grade as you can find) to have ready to go.

[MechEng83]

Spacer, yes. Live axle, no.

We tried this on this year's robot and it twisted it into a twizzler shape. I recommend using solid hex aluminum for your application. 6061 might suffice if the load isn't too high. We ended up using 2024 solid aluminum hex. That worked well for us.

[asid61]

6061 1/2" hex will not bend in drivetrain applications, as we had to substitute a few 7075 axles for 6061 during build and they held up through 2 competitions. This might have been due to to other drivetriain problems that stopped us from moving too much though.
6063 is considerably weaker than 6061, so I would be wary of using it. For prototyping, it might be fine, but it would be much safer to just purchase some 1/2" 7075 hex stock from Online Metals instead.

EDIT: This would be in our team's experience only.

[R.C.]

Originally Posted by asid61

6061 1/2" hex will not bend in drivetrain applications, as we had to substitute a few 7075 axles for 6061 during build and they held up through 2 competitions. This might have been due to toher drivetriain problems that stopped us from moving too much though.

I'm not totally following. Just to clarify, your saying that 6061 1/2" hex would be more than fine in a drivetrain application such as a WCD (or other drivetrain using live axle)?

[asid61]

Originally Posted by R.C.

I'm not totally following. Just to clarify, your saying that 6061 1/2" hex would be more than fine in a drivetrain application such as a WCD (or other drivetrain using live axle)?

I'm sorry, it did not bend for us. Our drivetrain didn't see very heavy use this year, and that might be why it worked fine. Teams like 254 probably would need the extra durability afforded by 7075, but for a prototype low-load drivetrain 6061 should be fine.

[Chowmaster4695]

Originally Posted by asid61

6061 1/2" hex will not bend in drivetrain applications

http://www.chiefdelphi.com/forums/sh...0&postcount=16

You stated they would bend here. Please give us accurate information. Our students use chief delphi to help them make decisions where others have more experience. If they see contradictory posts like yours then they and many others will be confused. Please edit your post.

Chow Out

[Gary Dillard]

Originally Posted by MechEng83

...twisted it into a twizzler shape.

Churros and twizzlers, this thread is making me hungry.

[DampRobot]

Originally Posted by R.C.

I'm not totally following. Just to clarify, your saying that 6061 1/2" hex would be more than fine in a drivetrain application such as a WCD (or other drivetrain using live axle)?

We've used 1/2" 6061 axles in a drive before, however, they were supported by bearings on both sides, and we were running 6" wheels instead of 4" wheels. We didn't see it twist up at all. YMMV.

Of course, with the 7075 VP stuff so cheap, easy, machinable, and strong, I would never order 6061 hex for drive shafts. They almost never come with the right dimensional tolerance on the OD anyway, whereas the VP stuff is good to go out of the box. So really, why use 6061?

OP, if you're fine with wrecking some material, go for the Churro tube. Otherwise, buy the real stuff from Vex and profit. I've seen Churro tube twisted up ("into a twizzler shape") multiple times at regionals, and I wouldn't bet much on it holding up.

[cbale2000]

We used some Churro for our collector on this years bot with no issues...



You can't really see it in that picture because the PVC spacers cover it, but it extends across the entire length of the collector, drives the wheels, and is only supported on the ends. Overall we've been very happy with it, especially because it's light and rigid (and because we already had some around when VEXPro ran out of their long hex stock during build season).

Now granted this application probably undergoes far less force than something like a drive system would, so keep that in mind when planning its use.