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Topic Review (Newest First)
12-21-2009 08:30 AM
oldred
Quote:
Originally Posted by jonahb
The only thing that would worry me about pre-heating a frame is that the chance to overheat it and change the carateristics of the material it self. There is a reason why they tell you not to drill or heat frames on Heavy equipment and Trucks (in my pick-up's book also). I have seen bulldozer frames (made a Cat d3 dozer from low track to a high track in a few seconds with the idler being pushed into the cab), excavator booms fail because of overheating the material and in some cases the material is greater than 2 inches thick!


Exactly what SuthnCustoms said about frames but just to add a bit more.

One of the (mis-guided) arguments about preheating is that you will get the metal too hot when the heat from the weld is added but it simply does not work that way, if welded properly the base metal will be no hotter when finished than if preheat had not been used and preheating is nowhere near hot enough to damage the metal. The base metal will sink off the heat and weld temperatures will be controlled by welding rate. When done this way the weld starts out much closer to the same conditions that it will be when finished as opposed to starting out cold with not only thermal shock to both the weld and base metal to contend with but also rapid and localized expansion of the base metal. Think about what is happening when you start out welding on cold base metal, you will be inducing a difference of thousands of degrees of heat into a tiny area which is not only going to cause high stress as the hot metal tries to expand against the cold metal but this same cold metal is going to chill the weld bead much too fast. You would not quench a red hot weld bead with water would you? While the effect is not nearly as severe as quenching with water it is still happening to some degree until the base metal reaches a workable temperature. When properly preheated the metal will have already expanded over a much larger area and thermal shock to both weld and base will be minimized, the temperature differences between the weld and base will still be significant but after the base reaches about 400 or so degrees the adverse effects are reduced to the point of no longer being a problem.


BTW, it is standard procedure to preheat bulldozer parts. I spent 35 years maintaining Caterpillar mining equipment and made just about every conceivable weld on everything from D4 bulldozers to the D11's.
12-21-2009 06:20 AM
SuthnCustoms
Quote:
Originally Posted by jonahb
The only thing that would worry me about pre-heating a frame is that the chance to overheat it and change the carateristics of the material it self. There is a reason why they tell you not to drill or heat frames on Heavy equipment and Trucks (in my pick-up's book also). I have seen bulldozer frames (made a Cat d3 dozer from low track to a high track in a few seconds with the idler being pushed into the cab), excavator booms fail because of overheating the material and in some cases the material is greater than 2 inches thick!
Heavy Equipment and Bigger truck's frames are made of a hardened steel,not mild steel,same with all crane and excavator booms and dozers.Most being a hardened wear plate steel,completely different animal from car and pickup truck's frames
Car frames and most pickup trucks up to 1 ton are mild steel frames.
Pre-heating is common practice for frame welding by the professionals on mild steel frames.
The reasons why they say not to drill and weld on them is most people don't know or have the capability to do the job properly.
Drilling a hole close to the edge of a frame will cause a crack and breakage,that's why a plate welded over the area the hole is needed and drilled is the common practice for added structural strength.

I've drilled and welded on many mild steel frames ,Jeeps,trucks..rods..etc and never seen a problem,jeep and 4x4 frames are regularly modified for different spring setups regularly by hobby garage welders and do just fine and these things are abused to the EXTREME,but they always take the advice of pro's on the setup and right way to do it,prep,preheat,fish plates,,etc
12-21-2009 02:45 AM
jonahb The only thing that would worry me about pre-heating a frame is that the chance to overheat it and change the carateristics of the material it self. There is a reason why they tell you not to drill or heat frames on Heavy equipment and Trucks (in my pick-up's book also). I have seen bulldozer frames (made a Cat d3 dozer from low track to a high track in a few seconds with the idler being pushed into the cab), excavator booms fail because of overheating the material and in some cases the material is greater than 2 inches thick!
12-20-2009 10:21 AM
oldred Fellows look at the amp ratings on the 110 machines, you are asking for trouble trying to weld a frame with an amp rating that low without preheating first. Theoretically you could heat each joint but in addition to the extra work you would most likely run into warpage problems. The problem is the heavier metal acts as a heat sink and will chill that low amp weld bead much too fast which will result in thermal shock to both the bead and the base metal. What happens then is that even if the bead appears ok it will usually be brittle and there will be under-bead cracking.



Try this, take 2 pieces of 1/4" plate about 4" square and butt weld with the 110 machine edge to edge without any sort of preheat then try it again after heating both pieces to about 400 deg. (just too hot to touch with your bare hand). Look at the difference in the welds, that's the problem and a 110 machine simply does not have the energy available to get around this. I know there have been improvements in 110 machines but that does not make up for the fact that the total energy input available is too low to avoid the problem, those bigger coils may increase the duty cycle but they can not create energy and only have what energy is available to them to convert to welding current.


AddShoe, A 110 welder could be used to weld some areas with proper preparation and proper pre-heat but to build a frame this becomes impractical. There are some other very skilled and experienced MIG welders (weldors) here that will probably chime in soon and some of these guys will recommend not even trying small frame welds with pre-heat, I can not disagree with them as their reasoning is not only sound it is the accepted industry practice. I personally have had good success welding heavier sections with a 110 MIG using preheat and for the occasional small job I believe this to be acceptable but the extra weld prep and extra attention required really makes it impractical for something like an entire frame.
12-20-2009 09:48 AM
speedfoos I made my frame with my 110 Lincoln. I am not worried at all about its structural soundness. I made two passes on the welds and am willing to be guarantee mine and my family's lives on its integrity. That statement is not based on ignorance.
12-20-2009 09:44 AM
ogre
Quote:
Originally Posted by AddShoe
oldred are you saying it would not be a good idea to go into assembling a frame with this welder?
are you trying to justify the cost of a new welder to your wife or are you interested in the facts?
yes, your 110v lincoln will do what you want
12-19-2009 09:13 PM
cjperotti The model you posted will do whatever you need it to do.

110-volt migs have come a long ways since they were first introduced in the market back in the early 80’s. In the beginning, they were nothing more than a battery charger rigged with a cheap wire-feed attachment to weld and had a poor duty cycle. Today’s 110 migs have heavier coil windings with larger capacitors to accommodate what they are intended to be used for. Improvements in the wire-feed attachments have also been implemented.
12-19-2009 08:40 PM
amx180mph
Miller Matic

I use a Millermatic Passport Plus with a spool gun that is wired for 110v it welds just as well as my Millermatic 252 220V. I have a magnaflux system and test welds when ever I am concerned on overhead welds and hard to reach areas. The welds from either welder are very strong and very clean. I know nothing about the cheaper welders never used one so not much more I can add to this board.

Dale
Cunningham & Hersh Hot Rods
12-19-2009 08:09 PM
70455 Three phase welder is best for building frames, but most people won't have on to much money. So 220 would be the next best thing. 110 just not good idea for car frame. I wouldn't trust my life to the 110.
12-19-2009 07:18 PM
AddShoe oldred are you saying it would not be a good idea to go into assembling a frame with this welder?
12-19-2009 06:40 PM
oldred Those duty cycle ratings are a lot like HP ratings on compressor motors and most are optimistic to say the least! There simply is no comparing a 110V welder to a 220V and there is a heck of a lot more to it than just 1 extra minute welding time out of 10, the highest setting on most 110 machines is not really high enough to do a proper job on frame welding and the duty cycle will be a PITA. You can certainly do small frame welds with a 110 machine but this will require preheating with a torch due to the low amp setting and that makes it impractical for large jobs.


A stick welder (a DC machine) will do an excellent job on frames and with 7018 rods strength will not be an issue, HOWEVER doing this with stick requires a very different level of skill and doing it improperly could be disaster!
12-19-2009 06:18 PM
cobalt327 20 % duty cycle just means that you can weld 2 minutes out of 10 at max rating, IIRC.
12-19-2009 06:14 PM
ogre In tools/equipment such as welders, the maximum duty cycle is defined as the percentage of time in a
10 minute period that it can be operated continuously before overheating.
source wikipedia

20% duty cycle means that 2 min welding, 8 min cooling. do not turn the welder off, the fan is doing the cooling.
your 110v unit is 20% duty cycle. the 220v unit is duty cycle rated at 30%, 3 min welding, 7 min cooling.
keep what you have. not worth the $$$ to get 1 min more of welding in 10 min.
seriously, i have welder 20 min with my 20% welder @ heat 3 of 4

your welder welds 5/16" steel in a single pass.
your welder will weld thicker material in multiple passes.
you could theoretically weld 2" material with your welder. it would take for ever but you could do it...
12-19-2009 05:52 PM
AddShoe

This is the welder I have, found the pic on google images.

output range 25-135 Amps DC
welds up to 5/16" steel
20% duty cycle (any input on this factor would also be cool for the thread)
12-19-2009 05:20 PM
ogre i have the lincoln weldpac 100, 110v set up for fluxcore wire. it did fine welding in my mustII crossmember and boxing the frame. you have to grind fluxcore welds to make them look right. my welder is 20% duty cycle. i bought the 110v unit for portibility.
i won't say a welder is a welder, but a lincoln weld is a lincoln welder. input voltage has nothing to do with output voltage. if you look at lincoln's 2 small mig welders the 140 & 180. the 140 is 110v in, 30 to 140 amps & 33v out. the 180 is 220v in and 30 to 180 amps & 34v out. you can weld the same stuff with either one. the higher the amperage the thicker the material that you can weld in a single pass. you can weld thick materials with a small welder by doing it in mulitple passes. more heat on most materials will warp & stress the metal. usualy multiple passes is preffered over a high heat single pass.
the 110v lincoln will weld anything you want to weld on a car or truck. yes it will weld a frame and do a fine job at it. you must live within the duty cycle of the welder. the duty cycle is rated for maximum heat, at lower heat (that you will use most of the time) the duty cycle increases.
keep your 110v unit, it will be fine. i keep mine setup for fluxcore and do not own a bottle, but i wish i had a gas setup for mig.
i do have access to a mig at my friends shop, we do production ss exhaust welding with a 180t, often welding an hr with it.
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