wire speed

[markib71070]

DRAPER 1502T turbo
this is on min setting 1 wire speed 6

When I just pull the trigger (open air), the wire feeds smoothly and correctly... but as soon as I start welding I can hear the motor pulsing, and the wire feed gets jerky. during the "jerky" part, it is nearly impossible to get a good arc going seems to bounce of hte metal and burn back....
Each time I would check the tip, etc.... and the wire would feed fine so long as I was feeding in open air... that again, if I was welding it would do the same burn back to the tip

if i turn the power setting from min to max it will weld fine on thicker metal

It is as though it isn't getting enough voltage (starving while arcing).... or something.... I haven't cracked it open yet, but I was hoping someone has experienced this and can give me some good direction.

so today 7/4/2020 i went and had a play with the welder and set everything min 1 so was on lowest setting for body panel thickness, turned speed to 0 the slowly turned the wire speed up whilst holding the gun to the metal got to between 1 and 2 and weld sounded like bacon frying as people always refer it to
question is
other welders ive used wire speed has always been around the 5-6 mark and people ive spoken to said the wire speed is a little slow @ 1-2 and should be around 5-6
???? what you guys think...ty in advance Mark

 

[eddie49]

The effect that you are seeing, where the wire feed is smooth but becomes jerky when welding starts, is probably due to the design simplification on a lot of low-end welders, where power for the motor is tapped off from the main welding power.
At low power range settings, the available voltage will be low, so the motor will run slowly. Worse, as the arc is struck, the voltage will drop, so the motor voltage will sag, the wirefeed will stop momentarily which breaks the arc, allowing the motor voltage to rise again.
Larger machines avoid this issue by having a completely separate auxiliary power supply for the motor.
Some users solve this by adding an external stabilised 12v or 24v DC power supply.

 

[angellonewolf]

how old is the unit ?

 

[hotponyshoes]

Try in open air but pushing the wire into a bit of styrofoam or something. If its jerky then you have a motor issue (maybe clean and re grease?)
If not sound more like power issue as said above if power is coming from the welding current

 

[a111r]

What Eddie has described is a well known affliction of SIPs and Cosmos. You might find this thread interesting, https://www.mig-welding.co.uk/forum/threads/new-user-with-cosmo-170-sip-and-a-headache.8028/

I have done most of these mods. I did not find them a revelation, either.
In retrospect, it is far easier just to buy something inherently better, like a Clarke.

 

[markib71070]

thnx guys n gals for your replies.. yeh as most of you have said sounds like the motor is tapped in to the main welding power
clean and greased the motor still does the same as before..

 

[markib71070]

how old is the unit ?

not too sure ,ive had it for about 2 years and never used it till now as my SIP 150 wire feed started to play up
but the guy i brought it off brought it new and only run half a reel though it and was left in the corner of his garge after that

 

[hotponyshoes]

Is the wire pulling off the spool cleanly by hand?
Try opening off the feed rollers then pulling wire from the end of the torch and see if it pulls through smooth by hand.

It's not had that spool of wire sat in it for 2 years going rusty has it?

 

[markib71070]

Is the wire pulling off the spool cleanly by hand?
Try opening off the feed rollers then pulling wire from the end of the torch and see if it pulls through smooth by hand.

It's not had that spool of wire sat in it for 2 years going rusty has it?

no i binned the old reel of wire and replaced it...and yes the wire is pulling off the spool very cleanly

 

[markib71070]

The effect that you are seeing, where the wire feed is smooth but becomes jerky when welding starts, is probably due to the design simplification on a lot of low-end welders, where power for the motor is tapped off from the main welding power.
At low power range settings, the available voltage will be low, so the motor will run slowly. Worse, as the arc is struck, the voltage will drop, so the motor voltage will sag, the wirefeed will stop momentarily which breaks the arc, allowing the motor voltage to rise again.
Larger machines avoid this issue by having a completely separate auxiliary power supply for the motor.
Some users solve this by adding an external stabilised 12v or 24v DC power supply.

is there a way of fixing this so the wire feed motor has its own supply if so how easy is it to do.??

 

[angellonewolf]

If been left around ina garage replace the inner liner

 

[markib71070]

If been left around ina garage replace the inner liner

already have that was the 1st thing i done when i removed the old reel

 

[a111r]

is there a way of fixing this so the wire feed motor has its own supply if so how easy is it to do.??

See link in #5.
It is not easy. It involves modification of the mains wiring, adding a laptop 20 volt SMPS, a relay to the trigger path and overall, interpreting the SIP annotated circuit diagram and adapting it to your model.

But if you've the skills, it's not too hard either. I had all the parts in stock and did it over a couple of evenings. I spent far longer reading all the threads...

 

[markib71070]

See link in #5. It is not easy and involves modification of the wiring.

lol didnt see that ty ill have a looksy at that

 

[a111r]

First post here has the diagram, might save you some hours finding it!
https://www.mig-welding.co.uk/forum...feed-power-supply-alternative-approach.11532/

 

[markib71070]

ty

 

[eddie49]

is there a way of fixing this so the wire feed motor has its own supply if so how easy is it to do.??

If you have basic electrical skills ( e.g. domestic wiring or auto electrics ), a soldering iron and a voltmeter, I'm sure you can get the mod done. You may have, or know someone with, electronic knowledge, but if not then I'm sure the collective experience here on this Forum can assist you.
I have not looked for a circuit diagram for the Draper 1502T yet. Some photos of the front panel, the data plate, and inside would help.

Often people use a laptop power supply:
https://www.ebay.co.uk/itm/Dell-Lap...upply-F9710-PA-1600-06D1-19V-173/133131058157
Or a generic 24v 2Amp power supply:
https://www.ebay.co.uk/itm/AC-100-2...ight-Driver-Power-Supply-Adapter/253494602759

Even with a good stable source of power, the variable power controller for the wirefeed motor may be inadequate. The usual solution is to fit a modern Pulse-width Modulated ( PWM ) controller:
https://www.ebay.co.uk/itm/3A-DC-6V...trol-Switch-Controller-Module-MO/153887474936
This runs the motor with pulses at the full 24 volts, so that maximum torque is available all the time. The speed is controlled by varying the effective "on" time of these pulses. It gives a smooth and controllable speed over a wide range. From a picture of the printed circuit board we may be able to tell if the Draper already has a controller of this type.

As you can see, there is a lot of scope for tinkering and improving... Maybe you need to start by deciding if the rest of the machine is good enough, and suitable enough for your needs, to be worth investing your time and money. These factors include the range of power ( especially at the low end for thin metal ), the MIG torch, and the build quality of the whole wirefeed motor and assembly.

 

[fixerupper]

I have found with hobby type welders ...if you want weld thin material it's better to start with the welder on a higher setting and then turn it down until you find the sweet spot ..(.rather than start from the lowest setting ) ie good penetration with out blowing holes ...some times it's better to have more power but move a bit quicker...and/ or with something behind to take the heat away ...

 

[markib71070]

thnx again guys for the replies