Tormenta 2 - Build Diary

[Kenny]

Re: Tormenta 2 - Build Diary

It may be better with a end support, can you get a bearing which the bolt head will fit into and drill a piece of aluminium and mount to the base, i think the problem you have is the sprocket drive is trying to pull the smaller sprocket, support it so it can't get stress on sideways movement should solve it

[Ellis]

Re: Tormenta 2 - Build Diary

It has had a support on the other side of the sprocket since we started. That picture from a few posts ago is old, and doesn't show it. We have been super careful with the bearing, knowing the stresses involved could quite easily destroy it.

I'm off to once again dismantle the side of the robot (at least it's fast and simple, might take 5 minutes if I take it easy), as apparently dad has just bought goodies from one of the B&Q-type places down here that may help this.

We're not back to square one, quite, half way back perhaps but not all the way. I'm going to think about ways to avoid cottering (that should be a word, along with cottered!) all the way through the material and instead a little way from each side. Twice the failure point has been (as you'd expect) where we have drilled all the way through.

As well as that, we're going to turn the torque required to activate the limiter down.

I'll keep this updated throughout the day. Thanks for the comments and help.

Edit: and incidentally, the rest of the machine is working nicely. Famous last words, perhaps, but the drive rig as a whole, batteries-thru-speedos-thru-motors, is showing positive signs. The previous machine didn't get this amount of drive testing.

[harry hills]

Re: Tormenta 2 - Build Diary

http://www.youtube.com/watch?v=p6PZhONZ3Ac

[Liftoff]

Re: Tormenta 2 - Build Diary

Any luck with the repairs?
As a last resort I'd suggest you ditch the reverse thread screw you're using, its too small at 1/4 diameter. A bigger diameter bolt will be much stronger. All you have to do is drill the sprocket, and drill shaft to a bigger diameter, say 5/16 (or 8mm) Buy an M8 or 5/16 24UNF taps and cut a thread in the drill shaft. Then lock all together using an M8 or 5/16 high tensile bolt. Then use a 3mm roll pin to cotter all together.
Can you post a pic of the problem area and the parts in question?

[Ellis]

Re: Tormenta 2 - Build Diary

The reverse thread bolt we have is no longer in use due to a slight technical issue, by which I mean it's in two pieces. :P

And, we can't use a bigger bolt because the bore of the sprocket can't be any bigger!

We're really stuck. We're rebuilding it as we had it last night, and we'll set the torque limiter low. We don't have time for anything else. At least, we hope, it will work visually, it just won't be able to lift much before the limiter kicks in.

I'll post pics of the final setup tonight, assuming it doesn't break for a 4th time. We have decided to try and fill any gaps that will allow slippage (and thus enough momentum to break again) with solder. The alternative would be glue, so this works.

[blazerbotics]

Re: Tormenta 2 - Build Diary

the amount of torque going through that sprocket, glue and solder wont do anything. I would really try and get it welded, its the easiest way without having access to a full machine shop.

[Ellis]

Re: Tormenta 2 - Build Diary

We know, yeah. :|

Well, we'll build it so that it works nicely below major stress, and leave it. Discussing the potential of Mario welding it for us at MMM.

May just move the weak point to the next thing (gearbox?) which will probably be more expensive!

[Liftoff]

Re: Tormenta 2 - Build Diary

Agree...solder not going to help much, adhesives - depends, I've used adhesives which stick to metal like welding, but I doubt you have any access to those...I'd go with welding as said above. if you don't have access to welding I cant see any way out if not by up sizing the sprocket hole ( looking at the photo below you have more than enough space for that)

[Ellis]

Re: Tormenta 2 - Build Diary

We could potentially up-size the hole by a mm or two (has been drilled out since that picture) but we're reluctant having experienced the power involved.

Well, Mario has extremely kindly offered to help. We think making it to the House of Chaos shouldn't be too difficult, in which case we'll have at least one skilled person leaning over the thing who will guide us. If he thinks a bigger hole is necessary, may a bigger hole be drilled!

I have a feeling he intends to just weld the buggery out of it, though. :P

We'll build this, avoid breaking it, be happy, and let Mario do the thinking if we can stop by.

[Liftoff]

Re: Tormenta 2 - Build Diary

good to know you found someone to help you out, it would have been a pity if it didn't work 100% after all the effort put in this build!
Have fun :wink:

[maddox10]

Re: Tormenta 2 - Build Diary

In the end, it became welded. And rewelded after the first test. And made a spare that broke by looking at it. Wrong kind of steel for the axle.
That motor and gearing put a mountain of torque on that poor little sprocket.

Oh well, I hope the last fix I created will do the trick. We'll see at Maidstone.

If this doesn't work, I'll weld the bugger out of it.

[Ellis]

Re: Tormenta 2 - Build Diary

Mario has been great with this, in both the results and the turn around time of new potential solutions.

The latest I believe was a single piece of steel, turned down to a shaft on one end (for the sprocket) then left large to screw onto the drill shaft, with dual grub screws.

If this breaks, I'll genuinely be surprised. Indeed, we shall see at Maidstone!

--------------------

My internet time is almost up so I'll keep it short in saying thank you to everybody at MMM so much for a fantastic event! We had a brilliant time, despite the issues obvious to those there (Mmm smell those motors burn! Hear those gearboxes strip!) we managed to come second in the main event, which was completely unexpected. All thanks to those who helped us out, many names escape me, but you know who you are.

For a first outing with our second robot and our third event ever, we're pretty happy. Pretty major changes will have to happen to make T2 more reliable, a rethink of our drive motors mainly, as well as improvements on the lifter control as the current setup is (electronically, I mean) clunky.

I'll try and do a proper write-up once we're through Maidstone and have a full damage report!

Ellis

[PJ-27]

Re: Tormenta 2 - Build Diary

Videos!!!!!!

[Ellis]

Re: Tormenta 2 - Build Diary

Using a dongle which is excruciatingly slow, can't upload footage until we get back home really. Hoping others will start uploading as we're equally desperate to re-watch our/the fights!

[Revsmin]

Re: Tormenta 2 - Build Diary

Got pics:

Album