Oerlikon mig welder 'EZ'wire feed, problem... ever heard of that brand?

[EastGrinstead-guy]

Hi all.

I have been using an old Hobart 150 mig for a while on car bodywork (it's very good) but bought a bigger mig welder from Leicester recently (via certain online auction website) to help with fabricating larger items such as suspension brackets etc.

It is an Oerlikon 17OC

The machine works great with plenty of power but after maybe an inch or two of weld it the wire slows down, and if you keep the trigger on and watch the wire coming out, it gets slower and slower and eventually stops. The wire is not binding up. If you leave it a few minutes it starts working again , for an inch or two etc.

The wire drive unit has EZ stamped into it, have you ever seen these ? I rang my local welder shop and they have not come aross this drive before.

I assumed the wire drive motor was actually stopping, but it still runs, you can hear it, but the rollers stop. If you unclip the pressure roller the drive roller starts turning again but can be stopped by squeezing between fingers, (ie, no torque)

I assume there must be some kind of clutch inside? Either that or a gear is slipping on a shaft or something. Any idea what could be wrong or how to go about repairing it ?

I'm in the middle of a DIY Landrover project.

Thanks!
Will

 

[weldequip]

First thing to do would be to change the Lining in the torch which can cause all kinds of annoying feed trouble (only a few quid), but if you can physically stop the wire feed roller between finger & thumb it sounds a little more serious... stripped gears inside the box
weldequip

 

[EastGrinstead-guy]

Hi, no bad gears noises, and the fact that it recovers after a few mins seems to rule out the teeth, so I was wondering if wire drives ever have some kind of torque limiting device (spring loaded clutch, like a takeup spool of a cassette player for instance) .

 

[weldequip]

Could be worn motor brushes, poor connection's or even a circuit board problem, difficult to say... got a picture of the feed assembly you can post?
weldequip

 

[EastGrinstead-guy]

Hi. Motor is running fine. Adjusting the wirespeed control while the roller has stalled has the effect of varying motor speed (audible) as it should. This effecively places the problem between the motor and the drive roller. I didn't think to photograph the wire drive before leaving the machine at the repair shop. But it is grey, rectangular and has the make E Z cast into it. The back of the motor protrudes through to the other side .

 

[rtbcomp]

Sounds like a gear or roller isn't fastened to its shaft properly ??

 

[EastGrinstead-guy]

Welder shop rang up saying they couldn't get it do do the fault, I drove there and got it do do it straight away, the roller stayed completely stalled even when taking ones fingers off it. So they said 'Its probably ya brushes mate'; so I showed them the motor still running , not very impressed , charged me £20 to gain me absolutely nothing, so I have the machine back here and I have taken the wire drive out and will dismantle the gearbox.
here is a photo of the drive.

 

[rtbcomp]

Does the shaft in the middle of the roller rotate when the roller has stopped?

 

[weldequip]

You can't replace the brushes on that motor to my knowledge... got the new motors in stock though
weldequip

 

[EastGrinstead-guy]

Hi, no the shaft does not rotate, and is D shaped, there is grub screw that fastens the roller to it. I;m suspecting its the motor spindle freewheeling in the motor pinion . Do motors come with pinion on? Going to dismantle now

 

[weldequip]

It will either be stripped nylon gears as I said originally or the main brass drive wheel on the motor shaft that has come adrift. Replacement motors come with the drive shaft, if it's stripped gears it's a full replacement gearbox/motor assembly.
weldequip

 

[EastGrinstead-guy]

HI, well, it was the pinion . It pulled off the motor with no effort. I couldn't really think of a good way of fastening it so I just crimped the pinion in the vice very slightly to make the hole ever so slightly oval, then i tapped it back on . Back together now and welder working. Just welded up a dumbel as a favour for the local gym!

Might buy a motor anyway as I don't think it is a permenant fix, let me know how much they are. It's 24 volt and attaches with three screws. The design Reminds me of the motors they put in R/C cars!

 

[malcolm]

Loctite of some sort would probably be a permament fix (so long as you didn't want to remove the pinion in the future).

 

[EastGrinstead-guy]

I figured the shaft was so shiny it would still slip, maybe putting some grooves in with a dremel might help the loctite sit there? Anyone repaired this fault successfully?

 

[EastGrinstead-guy]

just a little update, i gave the pinion a slight squeeze in the vice so it was a tighter fit on the motor .tapped it back on using a socket, all back together and welding a treat.

 

[rtbcomp]

The correct grade of Loctite should be OK, it requires the slightest clearance and relies on the absence of air to cure.

Now you've made the hole oval (crafty fix by the way!) there would be room for the loctite to sit anyway. Just make sure all the grease is removed and give it a couple of days to cure.

 

[Wozzaaah]

Try squeezing the shaft with some pliers or mole grips, if you can put some marks on it it should grip the inside of the pinion better than if it was smooth.

 

[EastGrinstead-guy]

hi, strangely enough, i did exactly this, i put some decent big moleys on the shaft, as tight as i could get 'em, even wobbled em around a bit, barely even scratched it. Very hard material.

 

[Wozzaaah]

Yeah they are pretty hard. I reckon loctite is the best solution so far, should work fine.