5mm 12 tooth gear mod to 4mm gear

[ripley802]

Well not really a train mod but figures I would post this one. So you may have come across this issue and already have a fix or maybe you have found the right size gear. (If you have found the gear, let me know..)

Anyway, here was my dilemma. Some of the older Tomy, especially the Talk n Action engines take a different gear that is not readily available. Here are the specs.

7mm Diameter, 2.5mm bore, and 4mm thickness. There are several places that have the right specs just the thickness is 5mm. These typically will not work though as they are too big.

So I took the 5mm gears I had and then set out to make a "jig" to replicate the gear. BYW,I tried casting these in plastic which did work, but the plastic was somewhat flexible and I did not feel the would be the best thing to use. I scrapped that idea and went with plan B.

Step 1.
If you have a thicker piece of aluminum or steal that may work too, but I took a scrap piece of wood and I had some metal duct from my HVAC. I flattened the metal and used roofing nails to attach to the wood.

Step 2.
I had to try various size bits and practice at the depths, but I found that a 9/32 inch bit seemed to do the trick. Then test the depth by using an existing 4mm gear or scrap to test the dept.


Close up:



Step 3.
I used a dremal with a sanding drum bit to sand the gear down flush with the metal top.


Step 4.
Finally clean up the burs and then they should be ready to go.

Final result in comparison with the 5mm




I know not much of a difference but sometimes that all that is needed. Now once you have the gears you can use the tutorial @Super did to replace the gears.

I have swapped a few now and they seem to work great. This got my TnA Henry back up and working. I had super glued his hear but it kept catching and stalling out.


Let me know if there are any questions. Thanks.

**edit**
Link to other thread to replace a gear:
Super's Gear replacement tutorial

[Super]

Fantastic Ripley

Excellent bit of tooling there. I am going to make me a jig like this when I need a similar gear. Thanks for the tutorial.

[ripley802]

Fantastic Ripley

Excellent bit of tooling there. I am going to make me a jig like this when I need a similar gear. Thanks for the tutorial.

No problem. Yeah my first though was to use a large piece of 2x6 wood. It is about 14" long. I was going to make several holes then use a belt or orbital sander to do several gears at once, but that seemed like overkill. One at a time is ok because it litterly only take ls a few seconds to sand down.

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No problem. Yeah my first though was to use a large piece of 2x6 wood. It is about 14" long. I was going to make several holes then use a belt or orbital sander to do several gears at once, but that seemed like overkill. One at a time is ok because it litterly only take ls a few seconds to sand down.

By the way the metal is there so you do not sand down the wood too much.

I did that on my first attempt. But if you had some mild steel or aluminum that would likely be best.

At this rate Mr Ripley will soon be scratch building these locos lol!

Here comes t&a Edward

[ripley802]

Haha. Not a bad idea. If only I could figure out the circuit board.

[ripley802]

No pics of this, but the other day I made a very simple "wheel puller" of sorts. At first I had twisted the wheel which stripped it. After having to super give that one I wanted to come up with something a bit easier.

Basically I took a small piece of aluminum I had laying around which was about 1/8" thick. I cut a small slit in it the width of the axel and then about 1" long. From here basically I slip the wheel assembly in and position the device on a vise. I used a small punch but other tools would work to tap out the axel.

Now it is ready for the new gear.

I also am making the same jig I made above out of aluminum so that it is a bit more compact and easy to use.

[Super]

Look forward to seeing the finished product. I gave some though to this also, a while ago, and was looking into clamps that can be reversed but could not find one small enough at the time. I should keep looking but I want to see your tool first.

[ripley802]

Look forward to seeing the finished product. I gave some though to this also, a while ago, and was looking into clamps that can be reversed but could not find one small enough at the time. I should keep looking but I want to see your tool first.

Thanks super. Well as mentioned it is not much but it does the job. I may try to come up with something a bit better later on but this has been a life saver so far.

Here is the set of wheels and the tool I made. The axel slides in the grove, from there I place over the opening of a vise:


The thing at the top is the metal punch I am holding which I tap the axel out with:


Here is a pic of the "Gear jig 2.0" :


Again very simple, but effective.

I picked up the correct drill bit this weekend and the whole size is a bit better now. I only had a "wood" bit in 9/32". The one I picked up is a 9/32" metal bit, much easier to work with aluminum now...

[Super]

Looks to work very well and a lot better than twisting the wheels off. Good job.

Pressing the wheels out like that, instead of twisting probably doesn't remove too much of the inner plastic wheel, so, you could most likely get to remove the wheel 2 or 3 more times before the wheel becomes loose. If you mark the wheel on the inside to the axle you could press the wheel back on in a different spot every time you remove it so you can get "fresh" plastic bite.