DIY welding RC motor mount to board-trucks

[spinningmagnets]

Edit: after posting this, I went back and watched the entire video...he didn't figure out yet how to dial the system in to actually weld aluminum, but...this is still a great idea, and when I find a video or website with the info needed to complete the aluminum welding job, I'll post it in this threa.

Using a salvaged microwave oven transformer (MOT) to create a desktop welder for small aluminum welding jobs.

https://www.youtube.com/watch?v=fQXBNkaB1tU



[youtube]fQXBNkaB1tU[/youtube]

Here's an article on hooking up two MOTs in series to make a welder, and even though he's welding steel, there is aluminum welding rod available. Of course, I still need to find out what thickness of aluminum rod, and what volts and amps need to be used to weld aluminum. You can vary the number of wraps on the secondary coil of the DIY MOT in prder to lower the voltage, and by using fewer wraps, you can fit thicker wire to raise the amps.

One of the reasons store-bought welders are as expensive as they are is that they are adjustable. If you are making a welder to do only one job, you only have to adjust the wraps of wire once.

http://mods-n-hacks.wonderhowto.com...sing-parts-from-old-microwave-part-2-0146590/

 

[amberwolf]

I havent' watched the video so don't know if it covers this, but:


Keep in mind if welding aluminum, especially for structural stuff, you'll need to have a neutral gas (argon, etc) surrounding the weld area or the hot metal will bond with the gases in the air and make a (much?) weaker area. Essentially it's "rusting" it from the inside out as you weld it.


(I don't know how much of the heat treatment issue applies but that may play another part in strength, separate from the above and probably less important).

 

[psychotiller]

Welding aluminum isn't going to work. Especially if you want to have any structural integrity.

 

[spinningmagnets]

Thanks, amberwolf and psychotiller.

I prefer a harsh truth over a comfortable lie...If someone wanted to bond two aluminum parts together...what are the best options (other than buying a TIG welder and taking a night class at the community college)?

 

[psychotiller]

This is what I've done in the past. Clean both pieces really well. Then put a bead of JB weld around one side of the pieces where they meet. Make sure everything is square before anything cures. Then, turn the pieces over and put a bead of Jb weld on the other side where the pieces meet. Let it sit until it cures. Usually a day or so.

The parts will never move again. Unless you really REALLY want them too

-Edit
Also helps to make sure your pieces fit together fairly well before you JB

 

[Bob K]

JB weld is great stuff. Bolted AND bonded structures are the best. The bolting forces take the clamping loads and the
JB Weld takes the shear loads. Ultimate bonding of aluminum with JB weld is as follows:
1. De-grease with solvent
2.With gloves on ( skin oil really contaminates a bonded joint! ) sand both interfaces with no coarser than 180 grit wet or dry.
3.Apply JB weld and then ( while your gloves are still on) sand with 180 grit some more.

Note: this step breaks the oxide layer and the JB weld prevents new oxides form forming by virtue of blocking any air ( oxygen)
from coming into contact with the newly bare metal. This is good for and extra 33% more shear strength.

4.Lightly wipe off the excess grit and sanding dust ( goo, actually ) and re-apply more JB weld.
5. Using A piece of .007" diameter copper wire as a bondline spacer to control the bondline thickness
in three places minimum, then assemble and lightly bolt up the assembly just snug.

Note: .007" bondline thickness is CRITICAL for maximum strength. Less than .005" or more than .010" and shear strength falls off fast.

6. use 125 degrees F of heat to cure the JB weld for hours ( I usually go overnight) . This is vital for maximum polymer crosslinking
and maximum shear strength
7. Use a torque wrench and torque charts to final torque fastener.

OH, one more thing. OVER MIX YOUR JB WELD ! It has a long "pot life" so you have the working time
and incomplete mixing will nullify all of your above efforts.