Rough settings for spray and SC transfer on simple machine.

  1. Mattycoops43 Member

    Newport, South Wales
    Hi all

    I hope this is in the right place, I am really looking for pointers about spray transfer rather than SIP specific info.

    I have done lots of mods to my SIP 140, it is now welding reliably and well, so I have been practising and improving my welding. I have been doing lots of reading and watching on Spray Transfer versus other types of mig. I can get a lovely Spray transfer weld on horizontal welds.

    My question is about settings, I think I am over thinking slightly and getting confused. My SIP is now running a 24v wire feed PSU and one of the aftermarket motor/gearboxes that are on fleecebay. So I have variable wire speed and 5 power settings.

    Is there an easy way to measure or work out the voltage that relates to each numerical setting on the rotary power switch? I have been watching videos that talk about certain voltages for certain thickness's. I know the basics, if I make a hole it is too hot etc, but I am looking for some reference points, and I would like to start jobs without having to experiment too much to find the right settings.

    SO this brings me to my second question. I want to be able to switch between spray transfer and SC and have an idea what settings to aim for. I am getting spray transfer with the wire on lowest possible setting for lowest power setting, and then a tiny increase as power goes up, so even on highest voltage, I am still only welding on speed about 10%. If I then want to weld vertical, I have no idea what wire speed to start with.

    Have I got my head round the basic idea properly? Spray transfer is lowering the wire speed, effectively upping the current till the wire vaporises as it enters the weld pool, so to switch back to 'normal' welding I need quite a jump in wire speed.

    I have been a bit stumped by changing from a 20v PSU to 24v when I changed the motor and gearbox as I was struggling to get enough wire speed before and I didn't like running at 95% wire speed on full power as I was left with very little adjustment if needed. (possibly not helped by the previous motor burning out).

    Anyway, any pointers would be appreciated.
  2. matt1978


    What do you mean by SC?

    Also you couldn’t be further from the mark regarding Spray. If you reduce the wirefeed rate you will also be reducing the current. With Mig welding, wirefeed rate is directly linked to Current/Amperage.

    In order to know the settings you need to say which wire diameter your going to be using and also the gas mix. An Ar/Co2 mix will be easier for you, 100% Co2 Gas will make it difficult.

    If you put your voltage settings and wirefeed rate to the maximum and then adjust the wirefeed rate down until you reach a nice spray condition.

    The max voltage output from your machine is not high enough to match the maximum wire feed rate, in other words it can’t supply enough voltage to burn off the amount of wire which is why you thought that to get into spray that you need to lower the wirefeed rate.
  3. Wozzaaah

    Wozzaaah The wizard of woz Staff Member

    Wiltshire, UK
    Lowering the wire speed will put your machine into globular transfer, not spray.
    At the lowest voltage and WFS settings you’re already into globular transfer.
    It’s unlikeky you’ll get such a small machine into spray at all.
    Regarding measuring the voltage, just stick a multimeter between the contact tip and return clamp then operate the torch trigger and Jot down the voltages for each setting. You’re looking at probably between 18 and maybe 26v. Don’t forget to disable the wire feed first.
  4. Wozzaaah

    Wozzaaah The wizard of woz Staff Member

    Wiltshire, UK
    SC = short circuit (AKA dip for others watching)
  5. Munkul Member

    Cumbria, UK
    at low wire speeds it SOUNDS like spray but it's not. It's just burning the wire back and will drop a ball into the weld pool now and again.
    You need to measure your wire speed and work out what turn of the control knob gives you how many inches per minute.

    Then look at a chart or calculator like this:

    your machine will never get into true spray mode I wouldn't have thought, it won't be able to deliver the on-load voltage of 24v+ you need, even with a high argon mix. Ideally use 98/2 Ar/CO2 which lowers the spray voltage.

    Remember spray isn't the be all and end all, you'll mostly be welding 3mm thickness or under with those sort of amps, any thicker and you'll severely struggle for penetration. With 3mm or under you're better off with SC anyways.
  6. matt1978


    A lot will depend on the wire diamter that he is using, if it is 0.6mm which is quite common on these hobby machines then it is quite possible that the machine will have enough voltage to get into a spray mode. However I wouldnt recomend a gas mix with less than 5% Co2.

    2% Co2 is a mix for Stainless Steel and CrNi's
    Wozzaaah likes this.
  7. Mattycoops43 Member

    Newport, South Wales
    Thank you for the comments guys. I am using 0.8mm, with hobbyweld 5 gas. I was running on 0.6 before though and have only recently converted to 0.8.

    I had the thought of actually measuring the wire speed, maybe measuring time for 10m and working it out. I can wind the same 10m in and out so I don't use loads of wire.

    Ok, I have misunderstood something somewhere then. I have watched videos of globular and spray, and it definitely sounds like spray when I weld. but I'm not arguing with people who have the experience I don't. I'm not sure exactly what I have not understood though? So if the wire feed slows, the wire runs hotter, but it doesn't mean more current? What actually makes the current higher then? I am assuming the current is not a result of switching to a higher voltage.

    Is there anywhere that explains the theory better than youtube videos?


  8. Easiest way to work out wire feed speed is, run the wire for 15 seconds, measure how much wire has fed out of the torch and multiply it by 4, this will give you how many metres per minute you are running
    Mattycoops43 likes this.