eccentric feed roller

[Mr Burns]

A couple of years ago i bought a Sip mig welder.Had the usual wire feed problems. I braced the feed roller mounts, put in a separate transformer for the feed motor and still got erratic wire feed so i gave using it.
Now recently i decided to have another go at it. just feeding the wire (not welding) and looking at the feed mechanism, i noticed the feed roller going up and down. It seems the roller is eccentric. Should i risk buying a new roller ? Will the new roller be concentric? Should i buy a new welder? Does anyone have a spare roller i could borrow?
Any advice greatly appreciated!

 

[BrokenBiker]

the roller should have no play in it, should only rotate smoothly. If it is moving up and down it is releasing the tension at some point then applying it again at another, which is not what you want

 

[rtbcomp]

Is the eccentricity in the roller or the shaft or both? If both can you position the roller on the shaft to cancel out the eccentricity?

" it is releasing the tension at some point then applying it again at another," This will also vary the load on the motor and thus the wire speed.

Also check the idler roller, if that's eccentric it could force the feed roller to move up & down.

 

[Jan]

By 'up & down' do you mean laterally (across) or vertically (along) the drive shaft? Although the feed roller on my SIP machine was fine - after the bracing mod, of course - I bought a spare roller as I was buying & fitting other parts, so the minimal extra cost was well worth it.

 

[Rig Pig]

You need to strip the wire feed down and find out what's bent or badly machined, I'm guessing that the shaft is bent but whatever it is it's going to mess up the feed! You can probably sort it out with a flat surface and a vice and light hammer.

 

[Mr Burns]

Just took the machanism to bits, put the shaft on vee blocks.
No noticable eccentricity on shaft.
With roller on shaft eccentricity is 0.2mm. Dont sound a lot, but when feeding wire looks like a cow munching grass!

 

[Rig Pig]

Good old Chineese quality control! Do you know anyone with a lathe who would drill and bush it for you?

 

[Flapdisk]

Just took the machanism to bits, put the shaft on vee blocks.
No noticable eccentricity on shaft.
With roller on shaft eccentricity is 0.2mm. Dont sound a lot, but when feeding wire looks like a cow munching grass!

Could be the wheels aren't circular though mate or the hole is not in the middle, it might be the powered one or both