New user with Cosmo 170 (SIP) and a headache

[BChild]

You'll be happy then?

I'm happier........ I spent a lot of time thinking it was me not the machine and that was frustrating I knew what to do and how to do it but nothing worked right

My recomendation would always be buy a decent welder if you can - but if you can't then modify what you have to make it better but only as a last resort

I think you're estimate on time is, let's say, conservative I must have spent a couple of hours reading your interesting and compelling progress

Charging time, easy £25 per hour. First hour usually £35 each hour after £25.

I'd recon you've got easy 8 hours of tinkering, fiddling, coffee and biscuits, fitting, refitting, coffee and biscuits, writing, reading, coffee and biscuits, waiting! Fitting and failing, coffee and biscuits, refitting and testing etc.

It's a great result though, as many people don't cost their time into the equation so in that aspect a fine result.

It was a thought provoking series of questions and comments and for that I thank you sir - I think we all spend more time on stuff than we should or can justify if we costed it but the learning part pays dividends for future years - as far as electrickery goes wiring up a plug was about my limit till I bought this welder

Hope it prompts others to take little annoying idiosyncrasies of their machines and try to make them better, there are a lot of wire feed related issues with less expensive welders and as it's quite critical to success you're tenacity will I'm sure encourage others to do the same.

You know it could become the 'must have' welder, you should start buying them modifying and selling them on, get one over to TechnicalAl, Malcolm and others and ask for testimonials.

weldquip could be asking for exclusive distribution rights

well done that man!

Scarey thought and probably unlikely but it's been a journey of discovery and as I often say every day is a school day

 

[BChild]

Right bought a flowmeter to stick in the line between gas regulator and welder

I found two avaliable - one was 0-15 LPM and the other was 0-45 LPM

I bought the 0-15 one but on inspection is says argon gas on the chamber - anyone know if this will affect the readings (assumes yes)

Form a quick search

The density of Ar is 1.784 grams/liter, while the density of CO2 is 1.799 grams/liter.

Thats close enough for me not to worry

 

[shenion]

My flowmeters have Ar, Ar/CO2 and He scales.

The Ar and Ar/Co2 scales are near identical. At 25LPM, you can just see a bit of difference.

 

[BChild]

My flowmeters have Ar, Ar/CO2 and He scales.

The Ar and Ar/Co2 scales are near identical. At 25LPM, you can just see a bit of difference.

Yep I figure now that at my operating window around 10 LPM i'm not going to be too far out.

In hindsight I probably should have purchased the higher range one

When would you need to go above 15LPM in MIG welding? Around 10LPM seems to be the recognised setting as a starting point - I guess welding outside you can wind it up to compensate for a breeze in the absence of an effective wind break

Anyway now have an adaptor made up for the output from the flowmeter to the welder pipe so I can fit that tonight properly.

Next task for this welder is to mount the PCB away from the front casing - to enable me to remove the 10 turn pot from the board and mount it directly to the front casing - I can then fit the 0-999 counter to it (currently the shaft is to short to be able to lock the counter to the pot shaft)

I want to get the welder to a finished with the modifications stage before the training session with Malcolm and both the above are key to my plans for noting settings and being able to go back to them as starting points/references

 

[BChild]

Oh and in other news having a rotten Mini to weld up I skipped the make your own welding caddy/stand/trolley and bought a Clarke one off the "bay of E" - mainly because the Pub bottle of CO2 was chained up to the racking and close to the welder (for safety) and it was limiting the portability of the welder....... safe sure but not exactly practical or mobile.

Anyway it's how can I say............. Flimsy

- the bolts and washers are a bit undersized for the holes in the mechano bits so might have to get some more suitable washers and beef it up

- I can stiffen it up by welding a few braces here and there

- need to find a tool box that will fit in the base tray to keep all the consumables where I can find them whenever I need them







might as well have made my own

 

[BChild]

OK Finished the last remaining mods (some pics inserted)

Re-mounted the PCB to allow Pot to be mounted to the welder face (bit of nylon - cut slots and a cable tie will never be my finest hour but for the moment it will do)

Need to extend the thermal overload LED but that won't take long and as I don't run it on the high settings probably wouldn't matter but I'll do it anyway

Fitted the counter (0-999 on a ten turn pot)

Looks OK ish - not exactly OE but not totally out of place

Re-trimed the internal pot to get the wire to just creep when the trigger is depressed - it was a bit fast before

Did a bit of welding to evaluate settings before I go back and attack the mini

I like my welder now - I'm not sure what Malcolm will make of it but it's not half bad now even on that rubbish CO2 stuff - sure it will never be a portamig or any other high end machine but I reckon it will do what I need it to do and when it's worn out I'll justify buying a top end machine

The ten turn pot and 0-999 counter means that you can move it approx 15 clicks either side and still be in the sizzle zone, 15 lower and it's a softer sizzle, 15 higher and it gets fierce (bear in mind that's equivilent now to breathing on the old pot) So 30 click window or 1/3 or a turn leaves plenty of scope for trimming

I took some pics of some welding beads and a video which once I reduce it I'll try to host

 

[BChild]

Welder on cart

Regulator and Flowmeter set up

 

[Rusty]

Nice work that Man

 

[BChild]

At last videos reduced and uploaded

Power 1 - Wire feed 65

http://www.youtube.com/watch?v=hakmqe4gm5U

Power 1 - Wire Feed 75

http://www.youtube.com/watch?v=K0t-ALXG3HI

Following videos were on power 2 and 3 with wire speeds around 100

http://www.youtube.com/watch?v=Ir-hTJipGIA

http://www.youtube.com/watch?v=ySclnAr-DHk

http://www.youtube.com/watch?v=AktjM5DSo7A

 

[BChild]

I know

- some I'm not working fast enough (higher power runs)

- some I'm not working slow enough (lower power runs)

And for some reason I have yet to fathom my starts are always very spitty till the arc stabilises and I get into a run

I was thinking that maybe I need to start but keep the torch stationary for a couple of secs then start to travel

Anyone got any other comments - I couldn't get too close to the work with the camera as I didn't want to spark erode the lens

 

[BChild]

I'll try to do some more test runs tonight with a pause before I start pushing to see if that solves the problem unless anyone else has other ideas, the welder is nice a smooth now once you are into a run and the wire feed motor hums along nicely.

 

[BChild]

OK continuing to talk to myself

Did some more test runs and the above problem proved interesting

First I started by setting the welder to the lowest setting (1) and a very low wire speed (35 clicks) I then tried to start a bead run. I got all the same characteristics as shown in the tutorial where Malcom shows the effect of wire speed from too slow to too fast

Increasing it in 10 click stages resulted in a continuous run being possible from around 75 and it all got a bit fierce around 155

I tried the same on the next power setting (2) and needed 85 with it all getting too fierce around 185

Just for good measure I went and repeated the process on power setting 3 and needed 95 clicks with 155 being the limit (was surprised it was less than the previous power level)

I checked out the wire speed and converted the values to m/min (timed over 15 secs and x 4)

Pot = M/Min
10 = 1.08
20 = 1.80
30 = 2.16
40 = 2.48
50 = 2.64
100 = 3.12
150 = 3.48
200 = 3.96
300 = 4.92
400 = 6.00
500 = 7.56

Looking at the handy chart on wire feed speeds v material thickness 0.8mm to 1.0mm should be in the 2.5 m/min (40 clicks) to 3.0 m/min (100 clicks) so I was more at the top end of that plus a little bit which confused me a bit

So I turned it down and went and tried again and found I could start a bead at 40 below the figures originally used - I did need to wait before starting to move forward and I had to work a little slower as well as get the torch closer to the work but it certainly gives a fairly wide operating range - I wonder if this is a result of both the material and the welder warming up - ie cold start you need a bit more power but as the welder warms up you can trim it back a bit?

In other news there now seems to be a bit of play in the wire down the torch ie I constantly need to cut a short length off the wire before I restart and I didn't before - might be due to the welder being closer than normal now it's on a trolley but it seems odd

I also tried the thin metal technique again but found I needed to up the power a bit to be able to link the welds

I also found that welds aren't very good when you forget to turn the gas back on - it's very similar to flux cored wire with a completely different sound and weld characteristic let alone weld shape

I took some pictures but I need to sort them and make sense of what I have

 

[R Kraft]

If it is overrunning a little, maybe you will have to put a braking relay on the wire drive motor.
Robert

 

[BChild]

If it is overrunning a little, maybe you will have to put a braking relay on the wire drive motor.
Robert

I guess that means - going back to the schematics posted earlier and trying yet again to make sense of this electrickery thing!!!

 

[BillJ]

In simple terms, you need a relay that has normally-closed contacts as well as the usual normally-open contacts. Most relays you'll come across will have both. The normally-closed contacts are the ones that make the connection when the coil is not energised.

Connect the coil to a suitable supply that is only switched on when the motor is running (perhaps the output of your new transformer?) and connect the normally-closed contacts to the two motor terminals. When you press the trigger, the coil will energise and the contacts will open so they will not interfere with the motor. When you release the trigger and the coil is de-energised, the contacts will close and short the motor terminals together, abruptly dissipating all the stored energy in the motor and bringing it to a halt in pretty short order. You will see and hear the difference between that and the operation before this mod.

 

[BChild]

In simple terms, you need a relay that has normally-closed contacts as well as the usual normally-open contacts. Most relays you'll come across will have both. The normally-closed contacts are the ones that make the connection when the coil is not energised.

Connect the coil to a suitable supply that is only switched on when the motor is running (perhaps the output of your new transformer?) and connect the normally-closed contacts to the two motor terminals. When you press the trigger, the coil will energise and the contacts will open so they will not interfere with the motor. When you release the trigger and the coil is de-energised, the contacts will close and short the motor terminals together, abruptly dissipating all the stored energy in the motor and bringing it to a halt in pretty short order. You will see and hear the difference between that and the operation before this mod.

Damn - thats a fine explaination - I understood it and why it will make a difference

Need to go back and look at those schematics again but thanks for the explaination

 

[BillJ]

Oh, I forgot one important thing - the supply to the motor must be switched through the normally-closed contacts on the same relay. This means that there is never a situation where the power is switched to the motor but the normally-closed contacts have not yet opened (the relay takes a certain time to operate). If this happened the power supply would be shorted momentarily through the relay contacts, which is not good.

So unplug the positive wire from the motor. Then connect the common contact (the one that flicks between normally-open and normally-closed contacts) to the motor positive terminal, the normally-open one (that connects when energised) to the wire you just pulled off the motor and the normally-closed one (that connects when de-energised) to the motor negative (without removing the motor negative wire - leave that in place too).

 

[BChild]

So unplug the positive wire from the motor. Then connect the common contact (the one that flicks between normally-open and normally-closed contacts) to the motor positive terminal, the normally-open one (that connects when energised) to the wire you just pulled off the motor and the normally-closed one (that connects when de-energised) to the motor negative (without removing the motor negative wire - leave that in place too).

So a typical 4 wire automotive relay should do the job - I'll have a rumage, take a few pics of the schematic on the top of the relay and run thro my plan to meet your specifications above which I almost understand - almost meaning you've done a damn fine job of getting it straight in my head but electrickery

 

[BChild]

OK Pictures work for me so here's a few

Automotive relay (GM cos that's what I have a lot of) 30 Amp 12V - Suitable?

Schematic from the side

Bottom of the relay labeled with the pin numbers

So if my understanding is correct (doubtfull)

powering up 85 and 86 results in circuit being made between 30 and 87 so the circuit between 85 and 86 is closed all the time - Did I mention my lack of electrickery understanding

now I'm stuck

 

[R Kraft]

That one is a single pole, single throw.
You need a single pole, double throw.