electronic help

[wheresmejumper]

I just picked up a lovely powcon welder.welds like a dream, but it really needs a display for reading amps.
problem is the rotary knob has a big scale so a little movement means a relatively big jum in power
It doesnt need to be that accurate relative to actual amps, just a scale that I could set myself initially, to the rotary pot
I saw a thread recently about fitting a postflow device to a tig machine, something similar is probably out there for an adjustable readout maybe off the shelf?
any help appreciated

 

[wheresmejumper]

There is a display kit for the welder out there but 1 it only reads actual welding output, not preset amps and 2 its $300

 

[shenion]

Is this MIG or arc welder?

You can use a clamp meter and someone to write down the current while you are welding.

 

[wheresmejumper]

Arc welder
I should have explained more clearly.the actual amps of the display doesnt need to be that accurate, id set 100 amps to what I felt like was 100 amps.
but I would have that as reference point, and could then use the display to move 2 or 3 amps up or down.this is near impossible with the dial as it is.its too small for its almost 200 amp range in low setting
I could fit a dial that is huge in diameter, and draw a new scale around its perimeter, but thats not my first choice.

 

[wheresmejumper]

This is a similar model


and this is the thread where the post flow electronic mod was linked to.
thats the type of gizmo im looking for
http://www.mig-welding.co.uk/forum/threads/post-flow-timer-circuit.45617/

 

[Wedg1e]

Oo, that would take a bit of thinking about... even the MPI machines I work on tend to use a roughly-calibrated dial to guesstimate the output and then verify with a digital readout when the 'shot' is on.
You'd need something along the lines of a digital voltmeter fed from one wafer of a multiple potentiometer (the other wafer setting the actual demand from the machine) to show the 'demand' current, then have a relay that switches the DVM to the shunt that reads the 'actual' current when you press the trigger (or strike an arc on a stick set).
Scaling the pot to match the output would involve multitudinous cans of worms as few welders have truly linear response to the output dial.
I'd go with the bigger knob and re-drawing the scale

 

[wheresmejumper]

Whats the porn free way to search for a big knob?
maplins only have a smallish one

 

[Robotstar5]

Whats the porn free way to search for a big knob?
maplins only have a smallish one

Try "potentiometer knobs"?

 

[julianthegypsy]

Whats the porn free way to search for a big knob?
maplins only have a smallish one

Yeah, maplins is rubbish these days...;-)

 

[hotrodder]

Whats the porn free way to search for a big knob?

Hifi amps often have big volume knobs which led me to http://uk.mouser.com/ProductDetail/Davies-Molding/1940BE/?qs=O7pb%2bE5gJ7Q3/olPh3XiHA== If you click back to knobs and dials you'll find several multiple turn examples. I'm guessing these are designed for use with multiple turn pots rather than actually being geared which'd improve resolution a lot more than a slightly larger scale

 

[wheresmejumper]

Thanks hr, I was actually on that website yesterday, but im on a tablet pad thing and that site and me didnt get along.
so I bailed and got a 2 inch dial off a pizza oven on ebay!
cost me more,but saved on paracetamol.

 

[Robotstar5]

so I bailed and got a 2 inch dial off a pizza oven on ebay!

and you can cook your dinner while welding

 

[wheresmejumper]

Its for turning the heat up, so it should work?

 

[Sean]

have a look in the modifying sip thread someone had a real nice knob -looked like a safe dial, spin the knob in the middle and the outer moved at slower speed was it BChild ? in his mega quest to make a silk purse...?

 

[Jim Davey]

I was going to say fit a ten turn precision pot like they did on the old Miller Syncrowave. Has a dual scale bezel that shows 1-10 and an outer scale that shows 0-9 every full rotation clicks the 0-9 scale up or down depending on which way you turn it and the other scale shows you your graduations in between. Quite a nice way to do it as it takes a fair amount of pot rotation to make a small change in output current.
I got my last one from RS a few years back, I'm sure they'll still be around though. Looks a bit like the hand wheel on a combination safe.

EDIT: Just noticed the post above says pretty much exactly the same thing.