Gallery, Projects and General > The Design Shop
Microwave owen transformer spot welder?
BillTodd:
stop over thinking it! :hammer:
just stick with a 20A mechanical relay and stop worrying . it operates for a second or two then stops that's all!
if you want complication, add a temperature sensor and disable the thing until cool enough to restart.
Fergus OMore:
--- Quote from: BillTodd on November 22, 2015, 04:18:00 AM ---stop over thinking it! :hammer:
just stick with a 20A mechanical relay and stop worrying . it operates for a second or two then stops that's all!
if you want complication, add a temperature sensor and disable the thing until cool enough to restart.
--- End quote ---
I can pretty well agree. Frankly, adequate arc welders at a give away price are available to replace the complexities of cannibalising a piece of old scrap. As far as the spot welder is concerned, it can be a single side machine which is no more than a pressure loaded carbon arc rod tied to the arc set. Again, a couple of carbon arcs makes what was called Limelight by Charlie Chaplin. No, it isn't a joke it is a practical way of brazing if you have to go cheeseparing for one reason or another.
To answer the obvious question, I've done it, written about it, it was seemingly ignored and -who knows- ignored yet again.
Ah well,
Norman
John Rudd:
--- Quote from: BillTodd on November 22, 2015, 04:18:00 AM ---stop over thinking it! :hammer:
just stick with a 20A mechanical relay and stop worrying . it operates for a second or two then stops that's all!
if you want complication, add a temperature sensor and disable the thing until cool enough to restart.
--- End quote ---
Exactly,
I have an Italian Cebora unit. It is completely manual in use, plug in, place over job and squeeze the handles.....job done...
In complete contrast, when serving my apprenticeship, we had to make a tool box, the spot welder we used was bench mounted with an integral timer.....took the guesswork out of holding the handles together for too long or not long enough.... :zap:
PekkaNF:
--- Quote from: BillTodd on November 22, 2015, 04:18:00 AM ---stop over thinking it! :hammer:
just stick with a 20A mechanical relay and stop worrying . it operates for a second or two then stops that's all!
if you want complication, add a temperature sensor and disable the thing until cool enough to restart.
--- End quote ---
I propably forget to mention that I have 90C bimetal switch that I was thinking of putting there for overheating....
I have been a bit sick last three days and haven't rush with a mechanical construction. Partly also, because I'm waiting 18 mm dia 500m long pure copper rod (eyeball figure).
Idle mind had some time to play with the control part. I agree that it would be easy to manually weld with a proper welder about 2/3 to 2 sec welds, but this small welder will be reserved for a) study and b) very thin stainless steel (and other foils/wires) and friend of mine has a bandsaw welding aparatus refurbished by my old very small welding transformer that welds well, but it is pretty hard to control annealing, therefore a control circuit would be higly desirable.
Spot welder it will be, but following test hast be done outside of the living room warmth. Direct orders from ministry of the deomestic affairs. She was not amused of test to saturate the core and current measurement of simulated spot welding. Women!
Pekka
awemawson:
Pekka,
I don't think you need to 'over think' the design. Just make sure that your solid state relay is well over specified. At the end of the day SSR's are cheap as chips - if you fry one it's not the end of the world. Just replace it with a bigger one :)
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