Spot welding machine - video

**Jon** · Apr 9, 2021, 03:02 PM

Spot welding machine. By Make it Extreme. 18:48 video:

Previously:

Mini chainsaw - video
Portable air compresser - video
Tire vulcanizing machine - video
Pressure sprayer from chainsaw - video
Spindle sander - video

**Scotsman Hosie** · Apr 10, 2021, 03:59 AM

That's one helluva nice build. Only question I'd have is where — and how — did he electrically isolate the upper electrode from the rest of the handle and chassis?

**johncg** · Apr 13, 2021, 07:05 AM

There is no need to isolate the upper electrode since the lower one is isolated. Note that the output voltage on the electrodes is very low and since it is the secondary it is electrically isolated from the primary. If the chassis is grounded, it would be 0v and the lower electrode will be a couple of volts above the ground.

**Scotsman Hosie** · Apr 13, 2021, 09:37 AM

Originally Posted by johncg

There is no need to isolate the upper electrode since the lower one is isolated. Note that the output voltage on the electrodes is very low and since it is the secondary it is electrically isolated from the primary. If the chassis is grounded, it would be 0v and the lower electrode will be a couple of volts above the ground.

John,

Unless I'm seeing things, the lower electrode does not appear to be electrically isolated from the chassis. (Though it would appear to be the easiest one to isolate.) But regardless of the low voltage, the high amperage is going to weld everything in that handle up, if there's a dead short through the chassis.

Seems like a funny detail — not to at least allude to in the video.

Donnie

**Unkle Fuzzy** · Apr 13, 2021, 11:11 AM

The upper electrode has a copper cable running to it, so unless that cable fails it is the path of lowest resistance and the pivots will not weld up.

**johncg** · Apr 14, 2021, 01:48 AM

Originally Posted by Scotsman Hosie

John,

Unless I'm seeing things, the lower electrode does not appear to be electrically isolated from the chassis. (Though it would appear to be the easiest one to isolate.) But regardless of the low voltage, the high amperage is going to weld everything in that handle up, if there's a dead short through the chassis.

Seems like a funny detail — not to at least allude to in the video.

Donnie

Have a look at the 8:10 to 9:35 part of the video. The guy is doing and mounting the insulator for the lower electrode from brown Phenolic rod (composite material) which is a good electrical insulator and also heat resistant.