Millermatic 251 weld start problem??

Been lurking here for a while. Advice from this group's past posts lead me to buy the Millermatic 251 MIG. The 251 replaced a Century
120VAC unit. Obviously this was a big upgrade for me. I am *very* happy with the new unit but I am having a small problem that the group may be able to help me on.
For my first big hobby project, I am rebuilding my utility trailer. I'm using new 3/16 mild steel, .030 wire, argon/co2 gas and voltage/speed from the miller's chart. When I first pull the trigger, for the first to 1 second of welding, it pops and cracks. The gun pushes pack at me. Then after the to 1 second after start, it smoothes out and makes the correct sizzle sound (music). The weld quality at start is poor (no penetration) and then smoothes to a good quality weld (for me). The transition from bad to good happens fast, like someone turns on the turbo charger.
Some initial thoughts: After the purchase of the welder, I upgraded the house to 200 amp service and ran 4 awg out to the shop, so wiring shouldn't be the problem. The 251 has a "Run-in wire feed speed setting". I checked and it was set to the factory 100%.
One thought was that the argon/CO2 had not made it to the gun. I read in the group's archive about adding a switch to turn on the gas and purge the line before starting to weld. One piece of evidence that tells me that this is not the problem is that it happens every time I start the weld, even if I have only paused for a few seconds. The gas would not dissipate in the tube that fast.
Any Ideas? I plan to do some input voltage measurements with a memory volt meter. I will also try some over V and Speed setting.
Thanks in advance.
Humanfuse (I'm no stranger to electrocution)
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The 251 is quite tunable. It sounds like an adjustment problem with the initial arc. With the machine so new you should be able to get it serviced for free. Best to get this taken care of now before it goes out of warranty.
BTW MIller always over estimates the wire speeds on their charts. Try reducing the wire speed by 5% to 10%.
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snipped-for-privacy@hotmail.com (Humanfuse) wrote in message

Humanfuse
I use a 250 DX at work & have the exact same problem with our machine. I don't think its a setup problem I feel there is something in the design of this series of machines. If you want more detailed info on this problem go to the Hobart site & ask Dan about your problem. I belive he had the same problem with his unit at work but I don't recall if he ever sorted the problem out. Hope this helps.
Rod
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snipped-for-privacy@hotmail.com (Humanfuse) wrote in message

Ernie & Rod (et al.)
Thanks for the fast feedback. It sounds like it is time to get my local distributor involved in the problem. When I bought the welder, I could tell the owner was used to dealing with local industry and professional welders and not amateurs. As an amateur hobby welder, I anticipated that if I had a problem, the burden of proof would be on my shoulders to first prove its not a setup or cockpit error.
Now that I have your sanity check that it could be a machine problem, I feel a little more confident approaching the dealer for help and not look like an idiot. Two other strikes against my relationship with the dealer: I may have worked him a little to hard on the initial deal. He got his asking price, $1600, but I got him to throw in a Miller S&S auto dark helmet and a big Ag/CO2 bottle with the deal. Second issues, I'm a Purdue Engineer, He hates engineers. ;-)
Humanfuse (I'm no stranger to electrocution)
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Humanfuse wrote:

Regardless of the the deal you got, you still should get a fully functional piece of equipment. Since you have researched the problem, you probably know the machine better then he does. Make calls or appearances daily until the problem is rectified. He will probably send you to the local warranty repair rep. It is worth befriending the repair guy, as he is the one going to bat for you with Miller. If the sales guy doesn't like engineers, that's his problem.
Good luck
--
John L. Weatherly
Nashville, TN
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You can post your problem at http://www.hobartwelders.com/mboard/ and Miller enginer will reply monday. If you call Miller help number that is on your welder and in the manual they will help you trouble shoot problem over phone and or direct you to Miller service center. If the service center doesn't fix welder to your saticfaction or in timely manner call Miller and they will expidite the repair. That welder starts are controlled by electronics which have probably failed. Fix might be simple adjustment or a board swap.
Let us know how it goes.
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OH GOD not a PURDUE ENGINEER!!!!!
Forget I said anything, I didn't realize I was helping an engineer. Oh god the shame.
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Google is merciless. Look what you posted on 2003-08-14
"I started out as a machining/welding student, thne went to gunsmithing school, then to Purdue to be a metallurgical engineer, but somehow ended up with a degree in Theatre Tech."
So you would not help one of your old colleagues? ;-)
Note that I go quite apt at googling your posts, because they are generally so informative.
(and in case anybody wonders why Ernie ended up in Theatre Tech, this was explained on 2002-01-27: "The birth of Steel all over the world is an amazing study and is what made me want to become a Metalurgical Engineer. However, the math required drove me away, and I ended up with a degree in Theatre Tech." )
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Yes but as a machinist at Purdue, Engineers were my mortal enemy.
Plus my father was dept head for industrial engineering for 15 years.
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Sounds like Erine is an engineer at heart. He just hasn't come "out of the closet" yet. I think my welder problem is solved.
After installing the full bottle of gas, I still had the arc start problem. I had a friend with more welding experience have a look at the machine after lunch. He laid a few beads and the problem was gone. He watched me weld and spotted my problem right away.
I have a bad habit of starting the arc with the gun tip about an inch or more away from the joint. I then move the gun tip closer to the required inch. I practiced starting the arc with the gun closer and the starts are smoother. I need more practice.
Thanks for the help.
Humanfuse
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<snip>
Wow, that's the same thing the dealer said when he found out. :-) I embrace my geekness.
I have new information on the problem. The good wife let me have some more shop time today. So after getting the wood stove going, I got back into my welding project. I fired up the welder and opened the valve on the bottle. The tank was *empty*. I am 90% confident I closed the valve tight the day before??
Could the problem be that I was almost out of gas and the gas flow regulator wasn't working properly when the gas solenoid first opens?? The look of the first second of weld is similar to what I had experience when out of gas. The bottle I was using was the old one from the Century and I don't remember how much was left. Or, I could have had a full bottle yesterday and forgot to fully tighten the valve and it all leaked away. In this case, the gas obviously had nothing to do with the problem.
First thing in the morning, after using my slide rule to calculate the proper amount of coffee to add to the pot, (That's for you, Ernie) I'm going for a fresh bottle of Ar/CO2. I will give the group an update after some more testing. If it's not an empty gas bottle problem, my guess is that Ernie and Mr. Duncan are right about the arc start circuit being the bad or out of tune.
I'm not too concerned about the relationship issues with the dealer. I think he was *somewhat* kidding about hating engineers. I'll give him a chance to help me. If he won't, I will get the name of the local Miller warranty repair rep as John suggests. If it's not a gas issue, I'll post the problem at the Hobart site as Mr Duncan suggests. I'll also try Randy's suggestion to snip the wire. My owners manual also suggest this technique.
More later. Thanks for all the help to date. If it turns out that I was simply out of gas, I'm guessing I am about to get a bunch of harassment. :-(
FYI, In my last post, I stated I got a free bottle of Ar/CO2 with the deal. This was a miss type. For the free new bottle, I got pure Argon for future aluminum work. I am going to try pushing alum wire down the factory gun with an optional teflon liner. But that's another thread.
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Something that people neglect to do is snip the wire each time. I know it is a bother but to get a good start take your side cutters, grip the wire gently, pull to remove slack then snip it off at an angle. Try it and see if it makes a difference in your starts. I don't snip all the time but if the weld is for a test or critical I use my cutters. Randy

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snipped-for-privacy@hotmail.com (Humanfuse) wrote in message

have your run in set at 100% That is actually faster than what your wirefeed speed is set at on the front panel. What I am saying is that if your wire speed is at 200 and your run in is at 100% I beleive your wirespeed at first would be 10% higher than that. On my 250X I had an internal pot to adjust, and I had mine set set almost at its lowest point. This lets your wire come out much slower at first and after a seccond or so it gets up to the speed you have it set for on the front panel. this way the wire dont come slaming out and hit the material and burn back resulting in a much softer start.Your run in adjuster should be much better to set than my unit I believe you do yours from the gun. I would start at 50% and go down from there. Chub
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