Team Thrifty /Fifty Build Diary for Bitza

[PJ-27]

Just trying to avoid adding more components.

Its seems such a odd feature, what use does it have?

[PJ-27]

I'm using a Sabertooth 2x12 and it seems to have some strange characteristics on the built in mixing. All straight movements on the stick seem to have half power, and all diagonal movement (so moving only one motor) seems to have twice the power.

Dimension Engineering said this was odd, and suggested that maybe my battery just couldn't supply the amps to turn both motors at full whack simultaneously.

I thought this too, but I'm using a 3S 20c 2650mah Li-Po which should be able to supply more than enough power.

Obviously this is causing me great problems since I lack torque to tank turn effectively and my straight line speed and acceleration is half what it could be.

Any ideas? (I'm using those MFA Como motors)

Cheers,

[Mouldy]

Try turning the mixing off on the esc.... Then throttle up so both channels are running flat out (move stick to top left or right position for example) then compare your results to running with the mixing on... If it's better I'd suggest a dodgy mixing function on the esc.

[PJ-27]

Good idea, I'll give it a try.

[Laser]

What radio gear are you using?

[PJ-27]

Spektrum DX5E Tx and one of the cheapy DSM2 Rx's from Giant Cod.

[Laser]

Are you using the mixing on the transmitter aswell?

[PJ-27]

No I'm not because it has those stupid half throws.

[PJ-27]

Sorted.

Apparently if you have Switch 6 not in R/C mode then this effects the mixing.

I had it in this mode because this is the only way I could get the drive to fail safe. Something else I can't seem to get to work.

If I am in R/C mode when I shut off the Tx the motors creep forward and no matter how I try and adjust the trims, set the sticks on start up, or re-bind I can't stop it from happening.

Furthermore the lost signal shutdown never comes into operation, which would have me believe it is a problem with the Rx. Except it can't be due to what I described above about not being in R/C mode.

*brain explodes*

[PJ-27]

Got a problem with Spinza where the blade is no longer able to spin up.

At first I thought the problem lay in the fact that because the Ti is so bendy in some position it was putting additional strain on the timing belt. After faffing around for a few hours adjusting the tightness of the belt for a few hours I found this made little difference.

I've re-assembled, greased and oiled the blade assembly and it now spins free-er than ever but still refuses to spin up. In a check we started the blade spinning with a long piece of wood (chocks away!) and it was perfectly able to then spin up.

It's like the motor has lost all of it's torque, so before I start swapping bits out and spending money just thought I'd get other opinions?

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The pulley on the motor shaft also came loose before I could do much testing, and I managed to get oil on the main pulley so had some issues with belt slip!