[FTC]: Trivial things that can cause big problems.

[PhilBot]

During our first few days of really trying to build stuff with the FTC Tetrix hardware, I couldn't figure out why the kids seemed to be able to break, or jam the various HEX drivers I had purchased for the team.

Finally I figured it out...

The Tetrix kit includes a neat little fastner for attaching an axle to most plate parts. It has a slot and machine screw used to compress the slot and clamp down on the axle.

The key technique that seemed to be lost on most of the kids was that it's important to insert the machine screw into the part from the correct side.

If you look at the hole that bridges the slot, one half is threaded, the other is not. The idea is that you insert the screw through the larger non-threaded hole, and then screw it into the threaded side. Now if you tighten the screw, it clamps the piece down on the axle.

However, if you insert it in the other way, it serves no function at all, except as a really frustrating exercise for the kid, who, no matter how hard he tightens the screw, cannot get it to grip the axle tightly....

Hence the collection of broken tools and screws that need to be forcable removed from the piece.

So.... if you haven't already, I suggest you add this to your next "training" session with your kids.

Phil.

[ttldomination]

I have yet to receive my kit, but when we do, i'll be sure to look over that.

[Abra Cadabra IV]

Already found that out the hard way. Nothing was damaged too much, but it was a really frustrating way to waste half an hour trying to figure out the problem.

Thanks for posting this. It should save some other teams the frustration.

[gdo]

I broke and bent a few myself before noticing the error in my way. I can't believe I actually read the manual they gave us, although it could really use some additions to it.

BTW, when you get to mounting servos with gearing, don't waste your time trying to find the correct standoffs, its much easier to drill the holes out that get 1" standoffs, sand them down by an 1/8", put spacers to offset the servo, and then finally mount them, just drill four holes and you will feel much better after and save yourself a lot of time

[PhilBot]

Originally Posted by gdo

BTW, when you get to mounting servos with gearing, don't waste your time trying to find the correct standoffs, its much easier to drill the holes out that get 1" standoffs, sand them down by an 1/8", put spacers to offset the servo, and then finally mount them, just drill four holes and you will feel much better after and save yourself a lot of time

I wouldn't mind seeing a picture of that....

[gdo]

Has anyone done servos with gearing so far? Maybe I was missing something in the way to mount them, but as soon as I tried to gear the servos for a 2:1, the spacing would not work from whatever I saw. Maybe we are just supposed to do 1:1, but I don't think my design will life all the pucks I wants to with 1:1.

[gblake]

Originally Posted by gdo

Has anyone done servos with gearing so far? Maybe I was missing something in the way to mount them, but as soon as I tried to gear the servos for a 2:1, the spacing would not work from whatever I saw. Maybe we are just supposed to do 1:1, but I don't think my design will life all the pucks I wants to with 1:1.

Back in March; using the Small (S), Medium (M) and Large (L) gears we were given for the Showcase, it was relatively easy to create any of the 1:1 gearings and to create the S:L gearing. However, I too had fits trying to assemble a S:M or M:L gear train. The big holes were not in the right spots to make it easy to create those ratios. So - You and I appear to be equally clever

I remember kludging something together back then but I didn't take pictures.

Bottom line: I think that the S:M and M:L gear trains can be built; but I don't thenk the result will be as elegant as the 1:1 and S:L gear trains. Maybe someone else has figured out a good way to build them?

Blake

[ttldomination]

Hm...we seem to be having trouble with the clamps for the axles as well, the axles seems right, but then it continues to slide around. I'll go back and check to make sure it's in right.

Thankx.

[jbbjjbt]

I have been telling the kids not to put in all four screws before clamping to the axle. I only recommend using three so one side of the clamp will still move.

[ttldomination]

Right now we are only using two. We are running low on screws and we will be placing an order soon. When we get our roughly 300 screws in, I expect we'll put more in. .

Does anyone know where to order the large screws? Like the really long ones?

[qwertyuiop[]\]

i believe you can get them from mcmasters. they have almost all the nuts and bolts you will need, and in a higher quality metal.

[ttldomination]

Are they legal? Are we allowed to purchase them?

[jbbjjbt]

Originally Posted by ttldomination

Are they legal? Are we allowed to purchase them?

If they are identical they are legal. So they need to be the same type,size and finish. I plan to order some.

Does any one know the length of the longer screws?

[ttldomination]

They should be in the little manual. I think they're 1.25" but make sure you check. Could you post the link here after you've ordered them?

[jbbjjbt]

Originally Posted by ttldomination

They should be in the little manual. I think they're 1.25" but make sure you check. Could you post the link here after you've ordered them?

Here are the longer screws I ordered from

http://www.mcmaster.com/

http://www.mcmaster.com/nav/enter.asp?partnum=90128A164

http://www.mcmaster.com/nav/enter.asp?partnum=90128A160

They look identical to me.