New user with Cosmo 170 (SIP) and a headache

[BChild]

Polo Wing now finished - Primered painted flated back and laquered with a quick rub of compound to blend it all in



So back to a rusty Mini

 

[madkayaker]

looks good no weld line

 

[BChild]

OK following on from a thread elsewhere on here

I've purchased some large spools of wire - both 0.6mm and 0.8mm size

The adaptors (plastic moulded cotten reels that probably cost 50p if that) that came with the welder are a sloppy fit and when I set it up they it was hard to stop the spools over shooting slightly after a feed - I realise that the bigger spools aren't as likely to unwind as easily as the little ones but I can't say I was impressed by either the quality or the fit

Temporary fix - wrapped the adaptors with insulation untill they were a snug fit - anyone seen this problem before?

Edited to add - what sort of tension do the larger spools need to be under?

 

[Benji]

Try tensioning the spool so that it just prevents overrun on your fastest wire speed. This should be adequate. As far as ill fitting adapters go, I have used offcuts of drain pipe as packers, notched to fit.

 

[BChild]

Try tensioning the spool so that it just prevents overrun on your fastest wire speed. This should be adequate. As far as ill fitting adapters go, I have used offcuts of drain pipe as packers, notched to fit.

OK - I'll set the tension for minimum overun on 50% maximum wire speed (since the wire feed transformer modification and reset of the pot on the board) when set to minimum the wire barely creeps out but I'm not using anything above 25% on the wire feed speed adjuster on the front of the machine so fastest wire speed would be way more than I need.

In fact the more I think about it the more I think I need to somehow make the adjustment on the front of the machine a bit finer - I'll have to consult my friend who has more electrickery knowledge than I do to see if this is easily do-able

 

[BChild]

Talking to myself a bit but...........

I think I'll chart the wire feed m/min for the 6 power levels and maybe 5 positions on the dial to see if the potentiometer is linear - which I doubt

Does the trim pot have an effect on the operating range of the main dial?

By this I mean having adjusted the trim pot to achieve the creep speed at the bottom wire feed setting have I made the main pot work in a narrow operating range where it is oversensitive to adjustments?

Are there guide values for rate of feed at various power levels?

As I said talking out loud but I've done a few searches on here and it seems that a lot of "hobby brand" have very sensitive wire feed controls but very few fixes

 

[BChild]

Sorry to continue to come back to this thread but I'm one of those keep it all in one place where possible type people!!!

I'm also not someone who gets on well with just trying stuff at random till it works - I need to understand what I'm trying sort of cause and effect process

If it's boring and not what anyone is interested in OK - I've only wasted my own time typing

So tonight I did a number of evaluation exercises to determine if I was even close to some of the settings I have read about on this forum as good starting points.

First

Gas speed too much is bad - too little bad (and 10 L/min seems to be a figure that comes up a lot) OK first point I don't have a flowmeter so resorted to measurement with what I did have to see where I was.

Take two new food bags, kitchen timer, and a 2.5 L jug of water

Measure 2.5 Litres of water into one and look at the size, tie it off - so now I have an idea of what 2.5 litres volume wise looks like

Flip the roller off the wire so no wire comes out (cos that would make a hole ) and using the other plastic bag place it over the shroud

Press the trigger at the same time as hitting the timer and release the trigger after 15 secs

Compare with same bag filled with water - Bag of CO2 looks slightly bigger than bag of water therefore my gas setting is slightly more than 10L per min but certainly in the ballpark so happy with that - I've marked the regulator now

Next

wire speed I was pretty sure that the wire feed system after the separate transformer mod had resulted in the welder no longer changing the wire feed speed with power changes but I needed to check to make sure.

So I set the kitchen timer for 10 sec and measured the wire output on lowest power and highest power

So armed with a handy little chart from elsewhere on here I had some guide figures

http://www.mig-welding.co.uk/calculator.htm

Results of initial max and min at max and min power settings

Max wire speed 2.6m in 10 secs for both settings

min Wire speed 0.25m in 10 secs for both settings

I've converted these figures to m/min later

Just to make sure I switched the welder to a random middle power setting and sure enough both results above still held true - so wire feed no longer adjusted with power levels - on this basis if I want a less sensitive potentiometer - ie less change for more movement (making it easier to find the sweet spot bearing in mind I'm on CO2 so it's apparently harder to find) I can maybe

Option 1 - change the potentiometer to one that gives wider working window for my normal welding tasks (car bodywork)

or

Option 2 - adding in a switched resistor

or

Stick with option one and change to thicker wire for heavier work if I ever need to do that as it seems from that handy little chart that you need way way less wire speed on 0.8mm compared to 0.6mm and this totally expains why I was working right at the 0% end of the scale on 0.8mm wire

So next I looked at the speeds for just one setting accross a range of wire feed settings - without a graduated scale it's hard to get a good approximation of 25% and 75% but at least 0%, 50% and 100% were easy

Data below

0% = 0.25m in 10 secs (1.5m/min)
25% = 0.58m in 10 secs (3.5 m/min)
50% = 1.02m in 10 secs (6.1 m/min)
75% = 2.16m in 10 secs (13.0 m/min)
100% = 2.6m in 10 secs (15.6 m/min)

All the above were carried out on 0.6mm wire and my only conclusion is it's probably not that linear toward the top of range but as I have't plotted it yet.....

So for the rotten mini that needs sills and patches using 20 guage steel (1.1mm?) I should be using (according to the chart) between 3 and 3.6 mtrs per min

So I needed to do some welding and see if I could find the sizzle

I did - the mini has another patch - no pics - it's still shocking but it's better than the last one - trimming the wire speed "sizzle" was present between 30 and 40% on the dial - so I measured the wire speed at the max end of the sizzle point

0.77 mtrs in 10 secs (or 4.62m/min)

Well thats a bit high going by the chart and explains my weld characteristics sort of a sausage extruded on the top!!!

So I resorted to running a few lines on a slice of 20 guage steel - at the same time I also adjusted the darkness on my autodarkening visor/helmet - another discovery

At min it's all a bit...... BRIGHT!! and I struggle with definition of the weld pool

At Max it's so damn dark I can hardly see the arc

So middle for diddle and hey I can see the pool and follow it - another discovery!!!

So that's it for tonight - You want pics of the weld lines?

 

[BChild]

Ok want it or not it's late so here we go

0.6mm wire, CO2 and 20 Guage steel on either bottom power 1/6 or 2/6 power.

Doing my best to weave and trying to see the weld pool while adjusting my visor to see the weld pool better



Yeah I know about the holes I kinda slowed up a bit......



Trying to show hight of welds



Trust me these are seriously flat compared to some of my previous efforts

Ahh moving on to that penetration thing - Flip side - the deliberate hole helps you orientate the weld runs



Some better than others - some subtle changes to wire speed and flipping between bottom power setting and one up from that

I'll get me coat

 

[BChild]

Right potentimeter used in my welder is a 2K2A - well thats whats written on it) now in the previous set up with wire speed coarsely adjusted by power settings and the potentiometer used as a fine trim that was probably OK but now the pot has total control and I think the adjustment is a bit coarse and I'm only using a maximum of 40% (mostly less than that) of it's operating range and as I did a bit more tonight on the teabag mini it's pretty obvious that small changes have a big effect and it's not so easy to find the sweet spot (it also appears to change slightly as the welder warms up which kinda disrupts your flow)

Annoyingly google has revealed that some A types are linear and some B types are linear all depends where it was made!!

So I guess I need to find out what the specifications are for it and what would be a suitable alternative

 

[weldequip]

Try it on Argonmix gas instead of CO2 & it will seem like a different machine
weldequip

 

[BChild]

Try it on Argonmix gas instead of CO2 & it will seem like a different machine
weldequip

I'm sure you are right but I have a few reasons why thats unlikely to happen

A Mini resto project belonging to my nephew arrived and took up a car space in my garage!!

I don't want to get involved in bottle rental for the amount of welding I normally do I'd be OK with disposables

Disposables are a complete rip off

It costs me £25 for a pub bottle refill and I've paid for the cyl to be tested and given a 5 year extension to it's life

It's a rusty mini - it doesn't need to look pretty just be solid

so I'll persevere with co2 and see if I can tweak the welder to suit the application as I'm probably never going to do any heavy work with it .

 

[BChild]

Right potentimeter used in my welder is a 2K2A - well thats whats written on it)

So thats a 1 turn linear 2K Potentiometer

Now how sensitive would a 2K 10 turn pot be

(Hotlinked images might not work)

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5222996

And I could use one of these for noting settings and incremental changes

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6251579

I do feel a plan coming together

 

[BChild]

You could rig it up to run from disposable gas canisters, just to try it on Argonmix. I know disposables work out expensive but, trust me, you'll notice a huge difference in performance...and might wonder why you've gone to all the trouble with the modifications (Don't get me wrong, a change in gas won't cure the inherent problems with some SIP machines, but the proper gas makes all the difference).
weldequip

I had disposable argon/co2 mix canisters when I first started - I guess the other issues with the welder got in the way of any improvement in my welding and to be frank it was rubbish whatever I used gas wise - untill I found this site I was completely convinced it was all me and that I shouldn't be allowed anywhere near a welder.......

I'm a bit odd and I know it - think of it like learning to drive a car with no power steering, no ABS and a crash gearbox - thats what I learnt in - it was hard work and difficult but ultimately you understood clearly what was happening as a result of your inputs.... I'm not saying it makes me a better driver but a clutch cable snapping 100 miles from home didn't result in a call to the AA and services of a flatbed - I just carried on driving without the clutch matching revs to speed thro all the gears.

So I guess what I am trying to say without being offensive or arguementative (because I value your opinion and understand your motives for the suggestions) is if CO2 makes my welding experience harder than it could be to master then I don't believe it's a bad thing

Like I said I'm a bit odd............

 

[BChild]

PS - if I can master the skills with a modified SIP how much easier will it be with a better quality portamig that works straight out of the box....

And I'd like to justify that once this crusty mini is out of my hair - after all the SIP will probably be well used by then

 

[BChild]

So no comments regarding the planned pot change or is it case that people are waiting to see the results?

 

[Jaeger_S2k]

Hi,
I've been reading this with interest and congratulate you on your staying power, beating this is a personal goal now. Probably what I would be doing too.

I have really only a couple of question to ask....

If you were to cost your time
(researching time),
(collecting materials/components time),
(time to fit said materials/components),
(time lost because of defect materials/components),
(time lost in identifying said failed materials/components),
and the raw cost of materials/components,
how much would you say the additional are standing at the moment?
Then what the machine cost initially?
What's the total?

I'm not having a go at you, but I think it's important to know the potential REAL cost of these 'good value for money', 'they join metal together' type units is.

Thanks

 

[malcolm]

I'm also enjoying the thread. I bought a used SIP just to see what everyone was on about. Experimented a bit but slowed up a little as what I really wanted to do was measure the speed and voltage variations in real time.

One thought though - have you considered pulse width modulation for the speed control? http://www.mig-welding.co.uk/forum/showthread.php?t=4481 Advantage is it ought to give the motor a little more torque, and ought to be less prone to speed variation through heat than the original.

I like the idea of the multi-turn pot. It'll look good.

 

[BChild]

Hi,
I've been reading this with interest and congratulate you on your staying power, beating this is a personal goal now. Probably what I would be doing too.

I guess it's ended up like that.......

I have really only a couple of question to ask....

If you were to cost your time
(researching time),
(collecting materials/components time),
(time to fit said materials/components),
(time lost because of defect materials/components),
(time lost in identifying said failed materials/components),
and the raw cost of materials/components,
how much would you say the additional are standing at the moment?

Blimey - very good points

Researching time - couple of hours on this forum maybe covers the wire feed brace, separate wire feed transformer and euro torch modification I would say

Materials all delivered to my door so far so zero time there

Time lost while modifiying it to make it work better rather than actaully progressing with the welder probably a fair few hours (Euro torch conversion was pretty much done and dusted in one evening but the wire feed separate transformer modifcation dragged on a fair old while due to other commitments and also the fact I was at a low ebb as far as any self belief was concerned with regard to my ability to weld or work with electrickery (not my favorite subject and I have to lean on friends for help and advice - something I don't like doing just because I don't understand it)

Cost of components I'll look up what I've spent

Then what the machine cost initially?

Can't remember exactly but I have in my head about £200 (ish)

What's the total?

It's not going to be good is it but I'm going to work it all out and get back to you!!!

I'm not having a go at you, but I think it's important to know the potential REAL cost of these 'good value for money', 'they join metal together' type units is. Thanks

No offence casused - great points and great questions

I don't need to work the money out to know that in real terms I would have been better off buying a better quality "portamig" from weldquip, however as I have stated earlier I didn't have that cash avaliable to spend - I guess if you have a budget it limits your ability to purchase the "best" and it seems in the case of some hobby welders you should expect to have to do some tweaking here and there!!

Just for discussion......

I guess while companies continue to produce hobby machines in a price competative marketplace they will try to skimp/economise on construction quality

When comparing machines without specific knowledge we all compare on price v specification - I didn't have a clue other than a target amp range.... so I know that's exactly what I did.

If SIP for example produced a machine at the hobby end of the market that was say £100 more expensive than the rest because they used

- better quality components (or some of the modifications that are commonly needed already installed)

- separate wire feed control

- a decent handbook that gave some proper information about set up and use

Would it sell? I guess probably not because the features and quality wouldn't neccesarily be recognised by the prospective buyers and they would also need to educate their potential market/customer so additional expense in advertising etc which is hard to quantify the expense v the sales

 

[BChild]

I'm also enjoying the thread. I bought a used SIP just to see what everyone was on about.

Blimey - thats nice to see someone who "can weld" (I've seen some resto pics you've hosted and was impressed) buying something that has a bad reputation and seeing if they were really as bad as their rep!

Experimented a bit but slowed up a little as what I really wanted to do was measure the speed and voltage variations in real time.

Sounds like a datalogger would be usefull?

One thought though - have you considered pulse width modulation for the speed control? http://www.mig-welding.co.uk/forum/showthread.php?t=4481 Advantage is it ought to give the motor a little more torque, and ought to be less prone to speed variation through heat than the original.

Hmm - I'll have a look at the link and try and get my head round it....

I like the idea of the multi-turn pot. It'll look good.

The dial "knob unit" has been delivered this morning and it's not ideal - well the idea is but it's quite small (pictures don't always give a clear indication of physical size) so will be difficult to operate with a gloved hand

Still waiting on the 10 turn pot....

Anyway having got one of the items in my sticky mitts I've had a look for a larger one and this looks much better as it has a larger knob that will be easier to work with a gloved hand and also a 0-999 number indicator based on the 10 turn rotation

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0811153

Picture looks like this

In black shouldn't look out of place on the front of the welder as far as add ons go?

Data sheet is here and that says knob size is 17mm diameter which is almost twice the size of the one I've already purchased

All dimensions on the link below

http://docs-europe.electrocomponents.com/webdocs/00ad/0900766b800ad527.pdf

 

[R Kraft]

If there was a decent schematic of the SIP pcb board, it would be easy to add a resistor.
The pcb is expecting 15-20v from the output transformer.
I don't have a SIP to do actual measurements so this idea is approximated.
For example.
At 30a and about 15v
The low speed trimmer would provide 4 or so volts, just to get the motor started spinning.
So the span of low to high speed would be about 11v with 9.5v, being in the center.
With the 24v transformer the span from low to high would be 20v, with 14v in the center.
A pm motor's speed is proportional to voltage so that would mean the motor at low amps is turning about 50% faster than it did originally .
A resistor in series with the pot should reduce the speed, and increase the resolution of the pot.
You could use a trimmer, so that you would end up with a high and a low speed adjustment, and a switch to give you high/low speed .
But with no schematic, I can't suggest where in the circuit to put the resistor.
Robert