How to shim your motor tower

[Pseudotectonic]

View attachment 121458

How to shim the motor tower:

1. Measure the ID of the motor opening on the gearbox (usually about 10 mm)

2. Measure the ID of the motor opening on the pistol grip (usually similar to above)

3. Measure the OD of the motor tower (usually about 9.x mm)

4. Wrap the motor tower with aluminium tape, first clean the aluminium surface with some alcohol so it sticks to itself better, wrap in counter-clockwise (seen from motor side) so it is less likely to loosen, build up enough layers until you get about 9.8 mm OD or whatever OD that is a close fit but with a little clearance

5. Test fit with a closed gearbox with pistol grip attached, it should insert without any force but with minimum rattle or side movement, rewrap if needed

6. Done!

Image credit:

- Airsoft Customs custom tower on youtube

- 3M Scotch Aluminium Tape

- Some random motor from Evike

 

[Rogerborg]

How much extra feats-percent will I get, mister?

 

[Pseudotectonic]

This will prevent the motor tower from dancing on the gearbox opening, hence pinion gear dancing on the bevel gear in use and putting on extra friction and wear, the motor will stay aligned much better and the meshing will be improved, the reduced peak loads from the reduced chatter can improve efficiency by probably a few percent, and it will sound better

 

[Sewdhull]

I thought everyone would make it so thier motor stayed in one place whilst in use.

Seems pointless shimming your gears and then let your pinion flail about as it rides the bevel because the motor isn't fixed to anything or slotted snugly into anything. Some might be lucky with tower gearbox fit ment. I had a mil play.

I used .5mm wall brass tube as a shim.

 

[Adolf Hamster]

Dont want it too tight though as you'll not be able to adjust motor height

 

[Pseudotectonic]

.5mm wall brass tube

Nice, you cut it yourself? Does it free float or glued down?

adjust motor height

Yes it should have a little play for free movement, a bit like shimming other gears

 

[Sewdhull]

Nice, you cut it yourself? Does it free float or glued down?

Yes it should have a little play for free movement, a bit like shimming other gears

Yes, for this type of thing on thin tube I'll use a drill to hold the tube and a file to cut the tube itself, just put it on the tube in the right spot, let it make groove and then file it as the tube revolves. Once you have a decent groove you can use a sawblade, then back to the file to finish it off. Deburr and it's ready.

I make it an interference fit, heat the tube and drop it on. 

If the tube has a bigger OD than needed, reduce that with wet and dry in a spinning drill before cutting.

This one didn't need it.

Or you can ream the opening to fit the tube, a 10mm reamer works but all this depends on how much gap you have to start with.

A bearing in the thin end would be nice but this tower doesn't have one.

The tolerances for some parts are really poor I have found in Airsoft.

View attachment 121468

 

[Pseudotectonic]

Wow that is labour and skill intensive but certainly a much nicer result than tape

 

[Skara]

This is one of those bodges I haven't tried yet!

You'll hear from me when my warheads completely destroy them gearboxes

 

[Sewdhull]

Wow that is labour and skill intensive but certainly a much nicer result than tape

It's just 10mins to cut and prep the tube, it's half a mil wall thickness.

Can't use a pipe cutter cos the cut piece is too short.