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Problem with TB2 leg extension when body closed up Options
Tarkas
#1 Posted : 06 June 2019 13:25:32

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I've finished my 1/144 Thunderbird 2, but there's a problem with the extendable legs. They work fine in the test phase before the main body is closed up, but once the two assembled upeer and lower body halves are screwed together, the rack and pinion gears on one side keep jumping teeth. This means that the legs extend asymmetically and won't fully retract because the upper or lower limit switches are triggered before one side is fully extended or full retracted.

I've taken her apart and reset the gears, and once again it all works fine until I rejoin the two halves. The obvious implocation is that screwing the upper and lower bodies together is somehow warping the gears. Anyone encountered this or have any ideas on how to fix it?

Thanks,
Phil, rather frustrated by this last-minute glitch Cursing
roymattblack
#2 Posted : 06 June 2019 13:47:44

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When I built mine (the Custom build on this forum) I replaced the fixing screws at the very front of the side rail mechanisms.
I drilled out the fixing holes a small amount and used much heftier screws so I could tighten it all down MUCH more so that nothing could move where it shouldn't.
When the upper body was finally fitted, all was well.

Roy.
darbyvet
#3 Posted : 06 June 2019 17:10:31

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I know many people have had this problem with TB2.When the top is off there isnt much weight on the mechanism and it works fine, but once you add the weight of the top part the gears start slipping. There 2 things that I did .First of all check the drive shaft from the motor.Mine was bent and when I straightened it I got less skipping.the second thing I did was add a washer under the gear at the top and middle of the gear mechanism.This makes the gears mesh better and stops the skipping.You may have to experiment with the thickness of the washer.If it is too thick the mechanism binds.I cant remember the exact thickness of the ones I used -I found them in my spares box from a tamiya truck build, but they were pretty thin.

Carl

darbyvet
#4 Posted : 06 June 2019 17:18:31

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here are the pics of which gears to put washers under and the drive axles to check

you do need washers on both sides.I didnt need any washers on the fron gear, but some people put them under that one too.
Carl

darbyvet attached the following image(s):
tb-3.JPG
tb-4.JPG
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