MILLER XR air cooled push-pull gun

By jbspeed Date 02-17-2010 03:15

Thanks for the reply Lawrence.....what do you mean by the Power Supply? I mentioned it is on a 251 that operates on 220 single phase voltage....the module that adapts the gun to the 251 has a run in dial for different wire sizes and is at the correct setting....you mentioned a synchronizing problem....I was wondering about that also...I do have the feeder tension in the machine set at their lowest and today there were a couple of "nesting" problems but only at the gun....tension too low at machine to wad up.....it seems the more attention i pay to the arc length the less problems with burn back i have...always have burn back into the tip when a wire wads up..the suggested wire speed for .035 is 520 at 230V ( if my memory is correct)..I have backed off this while welding 1/4" and seemed to weld fine....with the initial feeding of the wire through the liner I think the liner itself is too short for it is not pushed into the plastic cap at end of liner in gun and because of this it snags and will not come on though...what arc length is proper when welding with this gun? Am i correct in assuming the more amperage the longer the arc length? I appreciate you input....JB

By DaveBoyer (*****)

Date 02-17-2010 04:23

"always have burn back into the tip when a wire wads up"

Can You change the burn back setting? Perhaps the wire is burning back and sticking in the tip, and this causes the bird's nest.

Can You loosen the feed roller tension at the gun so that rather than bird's nesting it slips?

Are there any sharp edges in the gun making slivers that could bind the wire as it leavs the roller and enters the gun tip assembly?

The arc length is determined by the voltage, the amperage is detrrmined by the wire feed rate.

You may be holding the tip too close to the arc or running too high on voltage.

By ssbn727 (*****)

Date 02-17-2010 05:52

Hi jbspeed!

230Volts??? It's got to be a lot lower closed circuit voltage than 230V!!! :) :) :) More like 23-24 VDC!!! :) :) What's your gas flow rate??? Bring it up just a bit because of the increased gun distance from the work, but not too much... maybe 5 cfh more should work fine for you

Okay, 520 just a tad high but, I may be mistaken... If you can get it to weld with a good sized nozzle to work standoff distance, then you may just be within the ballpark so to speak... Now, what you need to know is with your gun, you need to have a CTWD (Contact Tip to Work Distance) of around 1/2 to 3/4 of an inch because if you're too close to the work, it's going to burn back and ball up on the contact tip... So dial down your burn back control down to zero, then increase your CTWD to 1/2" - 3/4" and start welding... If you see a bit of wire coming out from the nozzle end, and the rest is a conical shaped plasma arc column with a very bright stream in the middle, and the the sound slightly crackling and buzzing at the same time, and an ever so slight amount of resistance from the wire feed which you may have @ 520 IPM's (Inches Per Minute), then you should be achieving what you want in an Aluminum spray transfer mode... Also, are you pushing the puddle or pulling it??? In other words, are using a forehand technique, or a backhand technique instead and what position are you welding in??? In other words, is it flat, horizontal, vertical or overhead??? Finally, have you gone to the Miller website for some tips on Aluminum welding yet???

http://www.millerwelds.com/resources/articles/Common-MIG-Weld-Defects-GMAW/

Don't be dragging your welds when welding Aluminum!!! Push/forehand technique is the only way to go with GMAW Spray transfer with Aluminum unless you want alpine lace swiss cheese within the weld!!! ;) :) :) Also, if you had a different power source like a 350P with pulsing capability, or the newest one's with "Autoset" technology found on the MillerMatic 212 and 252's, you would have to only fine tune your setting as opposed to having the potential of setting too much amperage and voltage and causing much more difficulty in getting the power source to an optimal setting... This is what Larry was referring to with respect to synchronization of the gun and the power source/machine. ;)

Now remember that once the puddle is formed with aluminum, it doesn't take very long for the rest of the base metal to heat up also which means that you'll probably need to increase your travel speed slightly as you moving along the joint, other wise you may encounter the puddle widening on you and excessive reinforcement and/or distortion as well on the base metal, so go with the heat flow when welding 1/2" or less thick Aluminum... Once you get the parameters optimized by tweeking them ever so lsightly towards oyu own personal preferences, you can then ever so slightly adjust the burn back control on the wire feed control. NOT beforehand!!! :) :) :) All the best! ;)

Respectfully,
Henry

By jbspeed Date 02-17-2010 16:04

thanks so much for y'alls input......after working with the settings I was using 22.3 voltage and 346 wire speed...I have loosened up the tension on the drive rolls and this solves the birdnesting issue at that point....I am mostly welding horizontal and vertical.....always push the puddle...I am begnning to think the difficulties I have had with the burn back and birdnessting has been as much operator error than anything else due to too short of tip to work distance...NOW..the threading of the wire through the liner situation is as follows: the wire will come clear to the plastic cap that threads on the end of liner termination in gun and bumps into the cap....this is where I think the liner is too short as it does not fit into the coned area of this threaded plastic cap..I do not know where the "burn back" setting is....will refer "again" to the booklet that came with gun....by this being on a 251 I may not have this....thanks....JB

By uphill

Date 02-17-2010 17:16

I used a xr for aluminum and had some problems also. My problem was that the liner was too far from the drive roller. I moved the liner so it just cleared the smooth drive rollers on the feeder. I think the gun rollers had a slight knurl to them that haised havoc with the tip life if it was set too tight. I used this setup on a gas drive miller 44 trailblazer and really miss it. The aluminum end dump work got pushed out by the side dump craze arround here.
I remember none of the settings( or much else from 10 years ago)
Good luck

By mtlmster (**)

Date 02-17-2010 19:00

JB,
I feel for you. I've never had much luck running Al thru a liner. Al has extreme friction and resistence when sliding against another material. So in contrast I just use my spool gun with small 1lb. rolls of wire. That licked all of my Al wire feeding problems. My gun is really old, but it has given me much good service and satisfaction, because the only down time is changing the rolls and occasionally burn back on the tip when it fuses. Then I just throw the tip in my "to repair items" and put in a new one. I know miller has come out with better equipment since, but I really like my spool gun for this particular purpose. Also I believe spool guns have really gone up in price since I acquired mine, but if one is doing a lot of Al wire feed, it is definetly a plus on investment.

Just my .02

Good Luck
Steve

By Smooth Operator (***)

Date 02-18-2010 00:36

mtlmster, In my opinion using a spool gun is" stoneage technology" compared to using a machine like Lincolns MP350 w/python push-pull gun. Machine sets all parameters when you set it for your application ( mild steel,s.steel or aluminum).Only adjustment is trim control at gun handle, use this machine for all our aluminum structural/misc. metals work ( except handrail) also on S.Steel work. Bead looks just as good as a nice TIG weld. Still need to keep a spool gun for field work off a engine drive but other than that won't allow to be used in shop . PS GO PENS

By mtlmster (**)

Date 02-20-2010 13:43

Yea, your probably right, because I am from the "stoneage", and haven't used any new hi-tech equipment in years. Since I don't do much welding anymore the only opportunity I will ever get to operate the hi-tech stuff, will be if I know someone who has it and they let me try it out. BTW the only time I have ever used my spool gun was onsite welding. (Occasionally used in shop but not much). In the shop I just tig it and go on. I'm no longer a fabricator, don't have any hi-production work, therefore I'll probably never know what you guys are using other than what I read or see in an add.

I am pleased for you that there is new equipment for you guys to use that makes your job faster and easier. I'm sure that in the future as technology improves welding equipment will get even better than what you have now. I know it has changed a bunch since I started back in "69"! (Spool guns were Hi-Tech back then).

Take care, and thanks for your input

Good Luck in your business
Steve