Modifying Standard Gear Box

This board contains easy-to-do fixes on your new tanks from stock. This will hopefully help beginners to get the accuracy they want from their models.

Postby walter » Fri Apr 27, 2018 12:14 pm

In part 1 of scratch build Tiger 2 I was asked the question why I used a Taigen 5:1 gear box.
Way back I liked the idea of making my own gear box but quickly realized such a project would be very time consuming. When Taigen brought out a new 5:1 gear box it looked so ideal for my tank.
In later discussions it was stated Taigen 5:1 gear boxes had weak motors and low torque.What had me some what worried.
The old gear box making project surfaced again.
Having 3 sets of standard gear boxes laying around, why not try to convert them. If the project would fail nothing would be lost.
Removing the the motor driven gear and the motor with a new bevel gear and pinion and mounting the motor at the rear should be quite strait forward.
Before I carry on this mite not be appealing or even a good idea to a lot of members.
But here we go.
The motor driven gear has 45 teeth I wanted the modified gear boxes run slower so the bevel gear had to have the number of teeth increased.
I could only manage 7 extra teeth with a max. diameter of of 30.3mm. That would give a clearance of about 0.5mm to the neighboring gear.
The bevel gear has a face angle of 79 degree and pinion has 11 degree.
The first thing is I had to make a gear cutter.
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Postby walter » Fri Apr 27, 2018 12:17 pm

Cutter
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Cutter

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Postby walter » Fri Apr 27, 2018 12:18 pm

Cutter
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Postby walter » Fri Apr 27, 2018 12:21 pm

Standard gear box I used.
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Postby walter » Fri Apr 27, 2018 12:23 pm

I removed the motor driven gear
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Postby walter » Fri Apr 27, 2018 12:25 pm

Bevel gear cutting in progress.
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Postby walter » Fri Apr 27, 2018 12:26 pm

Finished bevel gear.
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Postby walter » Fri Apr 27, 2018 12:30 pm

This little gear with 15 teeth will be pressed into the bevel gear.
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Postby walter » Fri Apr 27, 2018 12:31 pm

Like that.
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Postby walter » Fri Apr 27, 2018 12:32 pm

The back of it.
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Postby walter » Fri Apr 27, 2018 12:33 pm

The first pinion I made in brass.
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Postby walter » Fri Apr 27, 2018 12:35 pm

But then I opted out for a steel one.
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Postby walter » Fri Apr 27, 2018 12:37 pm

Pinion pressed onto motor shaft.
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Postby walter » Fri Apr 27, 2018 12:42 pm

I made a small brass block to give the gear box frame rigidity and also a surface to attach the motor holding plate.
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Postby walter » Fri Apr 27, 2018 12:44 pm

The motor holding plate. The 3 bottom holes are elongated to give some fine adjustment to the pinion and bevel gear.
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Last edited by walter on Sat Apr 28, 2018 9:34 am, edited 1 time in total.

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Postby walter » Fri Apr 27, 2018 12:46 pm

The brass block fitted.
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Postby walter » Fri Apr 27, 2018 12:48 pm

From underneath.
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Postby walter » Fri Apr 27, 2018 12:54 pm

Gear box assembled. From the start I wanted to replace only the one steel gear, but on one of the gear boxes the steel gears where of bade quality and needed replacement. So I did the lot.
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Postby walter » Fri Apr 27, 2018 12:56 pm

All brass gears
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Postby walter » Fri Apr 27, 2018 1:00 pm

I also replaced the brass bushes with flanged ball bearings 3x6x3 and the drive shaft 5x9x4
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