MM251 Questions....

[Paul Cataldo]

Fellas,
I'm thinking of upgrading my MM210 to a 251, and other than MORE POWER, I'm trying to determine the difference between the two machines.
Some questions/concerns:

1. -I ran an 8awg romex wire for my MM210's outlet in my shop. IF I recall, 8awg wire is good for 40amps. Now I'm wondering how many amps the MM251 will pull?
IF I would have had some 4 or 6awg romex lying around, I would have just gone ahead and ran it, for future welder upgrades, but I didn't at the time, and I'm just wondering if this 8awg romex will be enough. BTW, the run of 8awg is about 55-60' from my electrical panel to my shops welding area.

2.
Here is a quote I read on IOC's ebay site, regarding the MM251:
"The Millermatic 251 also has exclusive timer features built into the operation for the saving of tips, gas, and wire when the gun trigger is activated but not welding"
Can someone explain exactly what this feature is, and how it works? I realize it's just a timer, but I'm not quite sure what this feature does.
Specifically confused about how it "saves TIPS"????

3. I know the MM210 can spray with .030 wire, and a 98/2 mix, and I'm really curious if the MM251 will spray MUCH easier than the 210, or what???? Does the 251 also require the 98/2 mix, in order to spray????

4.
Here is a BIG concern of mine. I have read numerous times on this forum, that the 251 has a VERY "soft" arc, and many guys say they do not prefer this soft arc. Well, I guess since I'm fairly new to welding, I'm wondering just exactly what a "SOFT ARC" is??? I mean, do I have a "soft" arc on my MM210? If so, then is the 251 even softer, or more crisp?? Can someone please explain sharp/soft arc's to me? Spending this kind of money is a HUGE deal for me, and I want to always make the right decision.

I guess that's it for now, and I appreciate everyone's help. You guys are so great, and one of my absolute FAVORITE things to do, is come home from work, and ask a question on the Miller board, and wait for replies!! I love it!
BTW,
If anyone knows of a place to buy a new MM251 for less than IOC's price of $1800-ish, let me know.
Thanks fellas...

[Paul Cataldo]

Anyone?
I figure there has to be someone itching to discuss the 251's arc quality here!
Thanks guys...

[Paul Seaman]

Paul:
The 251's arc is similar to, the 210 with a stronger arc force. If I were doing it though it would be a step toward the 350p.

Peace,

[cruizer]

Lets see,,,,,, the MM200's had a diode rectifier, and a couple of little boards The output specs were the same as the 250. They had a few quirks but with the right amount of rewiring over came them. This was a great machine.

Then along came the 250. Big board, and a SCR rectifier. Not a good machine due to wayyyyyyy to many problems.

The next evolution was the 251. IGBT (transistor) rectifier. Way cheap for Miller to produce.

Not too repairable and expensive to fix from an operator point of view. If a major problem existed, its basiscally a throw away machine. This unit does weld better than the 250, but not as good as the well designed 350p.

Another good design is the Lincoln 255, and 300, and esab 250/260's

[lramberson]

Lets see,,,,,, the MM200's had a diode rectifier, and a couple of little boards The output specs were the same as the 250. They had a few quirks but with the right amount of rewiring over came them. This was a great machine.

Then along came the 250. Big board, and a SCR rectifier. Not a good machine due to wayyyyyyy to many problems.

The next evolution was the 251. IGBT (transistor) rectifier. Way cheap for Miller to produce.

Not too repairable and expensive to fix from an operator point of view. If a major problem existed, its basiscally a throw away machine. This unit does weld better than the 250, but not as good as the well designed 350p.

Another good design is the Lincoln 255, and 300, and esab 250/260's

I was gonna stay out of this but this is too easy a target...

First, cruizer how as being a "Weld Tech" can you claim the unit is a throw away unit... If a issue were to arise you are supported with FACTORY SUPPORY second to none. My dealer and the 4 large shops I work with have had very little problems with the 251 and commonly call it Bullet Proof, and have switched completely Miller because of quality issues.

Second, you are comparing an Inverter machine to a Transformer machine, apples to pineapples, the only similarity is the common word apple.

Third, we can write a book on the design differences and + & - between the two or who is better, I just wish Lincoln would sponsor a site and I could go there a promote Miller on there dime with no proof. Did I say that

Lets talk ship time for each company & the issues there. I really hate to point out 3 weeks to 2 months depending on which machine is totally unacceptable for a manufacture to expect a customer to wait. Especially in a replacement part for a downed machine. Back to the service issue I guess.

I am done!!!!!!!

[Scott V]

I know the MM210 can spray with .030 wire, and a 98/2 mix, and I'm really curious if the MM251 will spray MUCH easier than the 210, or what???? Does the 251 also require the 98/2 mix, in order to spray????


The 251 will spray fine with 90/10 and .035 wire. It's a lot more powerful
then the 210 in that area. It would be one of the main reasons to buy a 251 over a 210. The 210 will spray on the top tap with 90/10 but it's really
does not have any extra voltage to play with.

[Miller Kevin]

Paul,

Let me see if I can claify a few things for you.

Fellas,
I'm thinking of upgrading my MM210 to a 251, and other than MORE POWER, I'm trying to determine the difference between the two machines.
Some questions/concerns:

1. -I ran an 8awg romex wire for my MM210's outlet in my shop. IF I recall, 8awg wire is good for 40amps. Now I'm wondering how many amps the MM251 will pull?
IF I would have had some 4 or 6awg romex lying around, I would have just gone ahead and ran it, for future welder upgrades, but I didn't at the time, and I'm just wondering if this 8awg romex will be enough. BTW, the run of 8awg is about 55-60' from my electrical panel to my shops welding area.

2.
Here is a quote I read on IOC's ebay site, regarding the MM251:
"The Millermatic 251 also has exclusive timer features built into the operation for the saving of tips, gas, and wire when the gun trigger is activated but not welding"
Can someone explain exactly what this feature is, and how it works? I realize it's just a timer, but I'm not quite sure what this feature does.
Specifically confused about how it "saves TIPS"????

Tip Saver = If you short the contact tip to the work the output of the machine will shut down and in most cases not damage the contact tip.

Gas Saver = If the trigger is pulled and an arc is not started after a short time the gas solenoid will shut off, weld output also shuts off.

Wire Saver = If the trigger is still depressed for 1 minute after the gas saver circuit kicks in the wire feed will also shut off and a help 004 will display on the meters


3. I know the MM210 can spray with .030 wire, and a 98/2 mix, and I'm really curious if the MM251 will spray MUCH easier than the 210, or what???? Does the 251 also require the 98/2 mix, in order to spray????

4.
Here is a BIG concern of mine. I have read numerous times on this forum, that the 251 has a VERY "soft" arc, and many guys say they do not prefer this soft arc. Well, I guess since I'm fairly new to welding, I'm wondering just exactly what a "SOFT ARC" is??? I mean, do I have a "soft" arc on my MM210? If so, then is the 251 even softer, or more crisp?? Can someone please explain sharp/soft arc's to me? Spending this kind of money is a HUGE deal for me, and I want to always make the right decision.

I guess that's it for now, and I appreciate everyone's help. You guys are so great, and one of my absolute FAVORITE things to do, is come home from work, and ask a question on the Miller board, and wait for replies!! I love it!
BTW,
If anyone knows of a place to buy a new MM251 for less than IOC's price of $1800-ish, let me know.
Thanks fellas...

Hope that helps,

Kevin

[stinkinlincoln]

The shop I have worked in for the past 4 years has 3 newer MM250s with digital meters, One older MM250 no meters, an ancient MM200, an MM251, and a lincoln 255. We run only T54 gas .035 er70s6. We short arc mild steel from 16 ga. to 3/8. We spray arc 3/16 to basically unlimited thickness (w/preheat). I used to use the old mm250, I now use the 251. I don't know why the 251 wouldn't spray with any gas that is reccomended for spraying, it has plenty of cajones for it, up to 31 volts. I have never needed above 26.5V. I find that the 251 has a very "tuneable" spray. I can get smooth spray from 23.2V 370ipm to 26.5V 430ipm to spray everything from 1/8 on up. The older 250 tended to just make more spatter if you tried to adjust for a hotter or colder spray. I notice that I run less voltage for a given wire setting than the guys running the 250s, If I try to run their settings I get serious splatter. According to the meters on the machines mine drops less voltage between Open circuit and weld voltage than the 250s. Roughly .3V versus 1V. People are probably referring to the inductance characterisics of the machine when they talk about 'soft arc'. Inductance levels affect the way the wire is pinched when it short circuits to the metal, this in turn affects the puddle qualities and penetration. As far as reliability of the 250s all of them have been in service longer than I have been there only 1 has had down time due to a gas solenoid. The 255 has been out of commission twice.
I should probably have a different username if i don't want people to think I'm biased against lincoln .Lincoln has made good machines but from what I've seen of the 255 it is not one of their better efforts. Bottom line, my 251 has 2 years use on it without a single problem, it welds, it welds good, its versatile, I really don't want to weld anything heavier than it has the power for. If I were equipping my own shop it would be on the list. BTW I believe 8 guage wire to be entirely adequate.

[kelly'$mygirl]

I don't relly like the 251 i would rather use my mm35 or mm250. Do u guys think if i ran a ER70s-6 .045 wire in my 251 it would weld better on 1/2'' than a ER70s-6 .035 wire? I usualy run the machine at 21.6V and 355 IPM for anything up to 3/4''.

[Scott V]

I was gonna stay out of this but this is too easy a target...

I think this is what Cruiser was saying.
Look at the board size of this unit and all the copper.
It welds way closer to a MM-200 then any MM-251.

This is the best 250 hands down. Too bad they quit
making it. It's also tougher if pushed way beyond
the duty-cycle. They fixed all the nagging problems
of the standard model with this unit, then canceled it???

[Danny]

I think this is what Cruiser was saying.
Look at the board size of this unit and all the copper.
It welds way closer to a MM-200 then any MM-251.

This is the best 250 hands down. Too bad they quit
making it. It's also tougher if pushed way beyond
the duty-cycle. They fixed all the nagging problems
of the standard model with this unit, then canceled it???

Scott, does my unit get to be at least second best, even with all its nagging problems?

The 251 is a nice unit, but this yellow unit just happens to be a nicer short arc unit then the 251.

I'd most definitely take a MM 251 any day of the week over a MM 250. You'd have to pay me to take the MM 250, and even then i'd just drop it into the scrap metal bin at the recycling center.

If I planned on doing a lot of spray arc, and the choice was between the 210 and the 251, I'd most definitely go with the 251.

[Scott V]

Scott, does my unit get to be at least second best, even with all its nagging problems?

The only real problem is the contactor's can go out on the standard unit.
The heavy-duty unit fixs that one. Some people do not like the fan
being as loud as a F-102 Delta Dagger

The circuit board on yours looks a little smaller though.

[gascart]

Yes the 251 has a softer arc .... makes beutiful beads consistantly. I love this machine with C8 gas for up to 3/16" work for short circuit and spay. 1/4" on up, use C25 for short circuit - or go with C8 and go into spray mode.

I'd never want to trade or sell this fine machine ... even though I have a 350P! (they both have their sweets spots)

You can spray with the 251 -- but you will be towards the upper end of the machine's capacity on heavy stuff. And the lighter weight M25 gun may get a little too hot if you're doing much spray.

The 350P has a rather harsh arc in short circuit mode - even with the inductance turned up - but if you want to spay - this machine will do it all day long! (Quite nicely, I might add) The heavier roughneck 4012 gun handles the extra heat in spay mode quite well - but is harder to manipulate than the M25. This machine is also very capable of making wonderful "spray like" welds on lighter stuff (like 1/8") in pulse mode. Quite an amazing machine.

Wiring: The 251 will draw up to about 42 amps on 230v, and the 350P will draw up to about 61 amps on 230v. Size of wire depends on load and distance.

[lramberson]

The more I read the less I want to get rid of my 251

[imported_brisland]

The Miller 251 is a great machine for the hobbyist or the professional welder welding 1/4" or thinner steel plate...I have used several of them and like the machine...however like the Lincoln 255 (I owned 3 in the past) they are not heavy duty for working 8 hours a day...5 days a week....I find the Miller gun is more durable than the lincoln for sure...if spray transfer is something you wish to accomplish properly (X Ray quality) this machine does not have the power or duty cycle for it....yes it is possible to do but not recommended...the XMT series is what you want for spray...I have not used the 350 for one reason...the price...you might as well buy an XMT at that point...

Bottom line...if you are not a business and you want to tinker in the garage this machine is a good choice ...if you want to make money with no headaches and run the machine 8 hours day...pay the extra...

-B-