..another Crack under motor

[solentlife]

When I repaired mine months ago - I never dismantled the shell as you have done. It would have to be a really serious case for me to consider that.

I scratched out the cracks to a shallow fine V and then filled with PU glue. Once set - sanded back and fitted the plates.

I have had ONE small crack appear since then where I had inadvertently while sanding 'lifted' a small piece of PU. That has been sorted with PlastWeld (MEK) ....

Nigel

 

[Ciccio]

..well maybe I had been a bit excessive this time... after the first cracks I decided to reinforce all arms with plast aid to possibly prevent others..then a second time I had openend it to understand why another Crack had come and found that the glue didn't fill completely that spot...and now for the third time I wanted to check if I had missed another...actually i think that now these last cracks might be caused by screws over tightening...however will fix metal plates once the glue has hardened

 

[Ciccio]

..hope this will hold...at least for some times..

 

[wichkans]

Just my humble opinion but when we see the cracking under the motor mount it always seems to start from a hole for the screw and the cause could be from over tight screws, weak plastic may also play a part.
I am not sure if using a material to fill the void will do much good but it does make sense to me that the metal plate or the plastic Plate used for the prop guards will help because of the plate acting as a way to displace the force of the screw head on the plastic under the motor.
You can imagine if the screws were over tightened deflecting the plastic around the screw head down and then the vibrations of the motor causing more stress on that area.

 

[solentlife]

Fact cracks appear from the screws is basically because cracks must start from an edge.
The screw hole is a perfect candidate ....

As I suggested - a combination of stress from motor and the weak area creates a situation leading to cracks. Of course if screws are over-tightened this will add to it.

Nigel

 

[DanMan32]

Are we sure those aren't scuff marks? I've thought at times I had cracks but found to actually be dirt.