Paperinik77pk

[MOD] Repairing an old 4,5v motor - adding a bit of Japan Tuning!

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Hi all,

today I tried something I was wondering from a long time - to replace a broken 4,5v Buehler motor with something newer.

This old thread gave me a good inspiration, but I still want my motor to run on batteries.

So, I took apart the old Buehler , removed the original metallic 13-tooth gear (2mm shaft), and got all the copper wire (which can be used for other mods :wink:)

20200326_191818

Now, time to find a substitute for the old glorious motor (this one was from 1969, even if the motor is a type II - probably in the past someone already repaired it).

Konichiwa - Capon-San!!! :snicker: Here it is the substitute...I know that it seems odd, but I had it around and it could easily fit inside the empty space left by the Buehler.

It's a Tamiya Mini 4WD Power Dash motor, capable of a stunning 19900-23600rpm at 3 Volts. Maybe too much, but it's the only 130-sized motor I had at home (I'm wondering where all the others of my old Tamiyas disappeared :sceptic:) for a totally failed Lego project.

...well... at least also the Lego motor is a 4WD...:laugh_hard:

20200326_191925

I fitted the original gear and the original front mask of the Buehler, then it was ready to go inside the chassis. It fits fine - it's not fully locked, but stays in place quite well.

20200326_192132

In order to get the electricity from the metallic chassis, I lifted the two metal contacts and I connected them to the motor contacts. A little pressure on the metallic connectors of the motor and everything's fine. The upper body part will block everything in place as usual. No soldering for the moment. Everything can easily return to its original status.

Then, a problem appears...the Tamiya motor specifications for electricity input go from 2,4V to 3V. Normally Lego motors work at 4,5v (or a bit more if using the 12v transformer in 4,5v mode).

After a fast trial at 4,5v the results were impressive - this motor was faster than any 12v or 4,5v motor I've ever seen. But after the trial, I went back to the normal 3v input, using a Lego battery box with two AA batteries and a wired connection to emulate the missing third battery.

It works! The motor can pull easily 6 cars (7710/7818) , but since it is designed to compete, it drains batteries (already at 50%) quite fast. So, before batteries run dry, I made a small video:

https://www.flickr.com/photos/138174786@N04/49702227807/in/dateposted-public/

It runs fine - but it can be improved on some aspects:

  • Motor Input. on Ebay there are lots of 130 motors with different specifications - as an example, some of them can accept from 3v to 6v, or even 9.6v, so teorically can be used with the original input of 4,5v. Some of these small motors seem to accept even from 3v to 12v...but I've to document myself better.
  • Number of Revolutions Per Minute. Probably, less RPM should better fit the original speed of the old Buehler. There is a specific "Torque Tuned" motor from Tamiya , but It is always limited to 3v maximum. So I'd go for a normal, slower Mabuchi 130 (around 12.000 RPM) 3v/6v.
  • Soldering. Once I've found the motor, two soldering points will give a better electricity flow - there are a lot of vibrations and this is surely an easy improvement.

These motors are very cheap, you can buy 10 of them for around 3 or 4 Euros.

One consideration on 3v instead of 4,5v...2 batteries instead of 3 mean less weight on the battery box or battery wagon - and LEDs can be used as lights without using any resistor. Maybe not the better choice for restoring a vintage 7710 - but it's always an opportunity. :laugh:

 

Ciao!

Davide

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1 hour ago, Paperinik77pk said:

These motors are very cheap, you can buy 10 of them for around 3 or 4 Euros.

Hi Davide,

nice!!!

I wouldn't go for the cheapest motors though. 4.5V is a fine LEGO product line from a very exciting time. It deserves the highest quality replacements parts:laugh:

Keep on the (very) good work!!!

Best
Thorsten 

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How did you remove the metal gear from the old motor and/or install it on the new motor? Just brute force?

EDIT: Also, the 4.5v motor is pretty easy to disassemble since it has screws: does anyone know of a guide for dismantling the 12v motor?

Edited by Commander Wolf

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11 hours ago, Toastie said:

Hi Davide,

nice!!!

I wouldn't go for the cheapest motors though. 4.5V is a fine LEGO product line from a very exciting time. It deserves the highest quality replacements parts:laugh:

Keep on the (very) good work!!!

Best
Thorsten 

Thanks Thorsten!!! I'd go for the Mabuchi motors, which are the ones I know best :wub:  - I've only to find a suitable RPM and Voltage :sweet:.

Obviously, this is only for replacement in case of emergency - long live the original 4,5v motors!!!:wub:

10 hours ago, Commander Wolf said:

How did you remove the metal gear from the old motor and/or install it on the new motor? Just brute force?

EDIT: Also, the 4.5v motor is pretty easy to disassemble since it has screws: does anyone know of a guide for dismantling the 12v motor?

Let's say brute force, but with a minimum effort (turn left/turn right) it came off easily! :laugh:

A thing I'd like to do (since these motors are new and pretty fast) is trying to use a plastic or teflon 13tooth gear instead of metallic one. This will allow me to leave the broken motor alone without recycling parts from it. I'll try to model a better motor support using 3d printing, or finding another solution to better keep 130 the motor in place and flat as the Buehler was, since I fear that even a sligtly different angle between driving and driven gear could damage the embedded transmission (and that's not easily repairable at all *oh2* ).

Ciao!

Davide

 

Edited by Paperinik77pk

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Here it is! :wink:

This «torque tuned motor» may be of interest for a shunting locomotive which woud pull long and heavy passenger cars. There is no battery problem as long as the 4,5V (or 3V) are delivered by track, the only thing is to avoid accidentally killing the motor with 12V.

Really interesting trial!

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56 minutes ago, Evans said:

Here it is! :wink:

This «torque tuned motor» may be of interest for a shunting locomotive which woud pull long and heavy passenger cars. There is no battery problem as long as the 4,5V (or 3V) are delivered by track, the only thing is to avoid accidentally killing the motor with 12V.

Really interesting trial!

It indeed is a good motor, looking at its specifications, but it seems they are hungry for electricity. I am searching currently on a site specific for robotic creations, and I found a motor that seems suitable for use with 4,5 volts input...it is used on Tamiya Gearboxes, so basically it's more or less the same use I'm going to do :laugh:.

There's also a little 130 motor tuned for solar power... :wink:

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Hi,

(sorry for my bad english )

the Motor problem was around 1990 allready actuell.

So I visit the lokal elektroniks shop, at this time thay sell industrial rest parts, include motors from Bühler.

After your post I search and find the old box with the rest parts from the special motors.

 

 

buehlermotoren-reste-klein-4.jpg

A few yaers later the problem was solved.

We plunder all Legoshop 50km around and found some "Service Kasten" in there back office.

(ups , sorry but I can only uploade 1 picture..... )

 

Torsten

 

 

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