how many of you guys have mild steel cages ? whos got chromoly ?

curious ,


i think in the certain application it doesnt matter as much as people think . to say 8.50 .....maybe when you need everybit for a x275 build . My cars C/M but could have saved some dough doing it ourselves with a mig welder using m/s

CM is LOTS lighter,mine is ms.

Mine was a mild steel 8pt, but I just cut that out and it's now being 25.5ed in chromoly. I'm hoping it won't weigh too much more than it did.

MS because I don't own a TIG welder YET. Been debating upgrading to small case 220 Lincoln or a TIG and keep the 110 machine.

Both of my cars are mild steel! couldn't afford cm.

ms here, for now...... the weight diff is not as much as you think it would be.


I built mine like back in 99, back then it was good to 7.50, of course that changed as the cars all got faster. I plan on taking the cage out from the firewall back and redoing it all next fall, cutting the old heavy rear framerails out and rebackhalfing it and doing a better job on the tinwork, I may even get some new rear quarters on it and habe them stretched properly......and maybe some real paintjob lol.

You'll save about 30lbs in a typical 10pt cage and around 100lbs in a full chassis.

5pointslow wrote:curious ,


i think in the certain application it doesnt matter as much as people think . to say 8.50 .....maybe when you need everybit for a x275 build . My cars C/M but could have saved some dough doing it ourselves with a mig welder using m/s

MILD steel encompasses a lot of territory.
DOM is stronger than ERW and there are also a lot of different metal compositions with differing amounts of carbon in many of both.
All mild steel does weigh about the same though their strength may differ some.

Don't understand the cost arguement. It cost almost the same for good materials shipped here. CM is easier to notch, bend, and weld. Either will do the job though. I prefer CM.

Let me add that we tig everything so that is not a variable.

mild steel here

Mild steel here also

Mines mild steel. If I switch it I will just switch cars.

whatbumper wrote:Don't understand the cost arguement. It cost almost the same for good materials shipped here. CM is easier to notch, bend, and weld. Either will do the job though. I prefer CM.

Let me add that we tig everything so that is not a variable.

One of the reasons most of us don't use cm is we can't tig weld.

Duffy doesn't even use MS anymore. I did the fronthalf in CM..... when I did the cage and stuff some 15 yrs ago all I had wad a mig.

Im in the middle of backhalfing and caging an 85 chevy swb, I just had him get it all in MS just to make life easier as Im doing it pretty much for free lol.

mine is cm now. tig welding sucks ass IMO but its worth the trouble if weight is an issue.the best advice i can give is if you want a cm cage or chassis and cant tig weld..pay somebody that can!

bbf-falcon wrote:

whatbumper wrote:Don't understand the cost arguement. It cost almost the same for good materials shipped here. CM is easier to notch, bend, and weld. Either will do the job though. I prefer CM.

Let me add that we tig everything so that is not a variable.

One of the reasons most of us don't use cm is we can't tig weld.

we are self taught. wanted a cleaner build on our first 10.5 car and this was the way to go. Bought a good machine and started playing.

bbf-falcon wrote:

whatbumper wrote:Don't understand the cost arguement. It cost almost the same for good materials shipped here. CM is easier to notch, bend, and weld. Either will do the job though. I prefer CM.

Let me add that we tig everything so that is not a variable.

p

One of the reasons most of us don't use cm is we can't tig weld.

I went with milb steel as that was all I had in my budget at the time I built mine cm was almost 250 more for the cage that I didnt have at the time.Plus buying a tig sure wasnt in my budget at that time the tig welding was not the factor as I can tig weld aluminum stainless or steel.Yes most of us dont have or access to a tig and some dont know how to tig. But if in your budget the cm is stronger but if you running on a real tight budget ms might be your answee

cm your joints gotta be real tight.........some will take that out of context.....

richter69 wrote:cm your joints gotta be real tight.........some will take that out of context.....

like a german virgin. gudentite.

I don't mind working with either material when TIG welding.

In the end the amount of time spent actually grinding/fitting a joint works out to about the same for either material when TIG welding. With the thinner wall 'moly you spend less time actually pushing against the grinding wheel cuz it's easy to remove, but you make more trips to the grinder trying to sneak up on the final fit to get a tight fitting joint. But with the thicker wall mild steel there are less trips to the grinder since you are looking for a little looser fitted joint, but you spend more time actually against the grinding wheel because of the thicker wall takes longer to remove. On the other hand fitting a thicker wall mild steel joint for MIG welding IMO is probably the quickest/easiest since you don't have to be (or want to be) super exact/tight on the fit up. You want a decently loose fit with MIG/mild steel to help with heat penetration so you don't end up with a mountain of wire weld puddle piled up trying to get good heat in there.

Tig welding between the two materials is another story, the thicker walled mild steel will always take a little longer to do vs the thinner wall 'moly. The thicker wall ms takes longer to get up to temp at the start of the pass, & the slightly looser ms joint takes more/larger filler material & more time to fill.

Some of the time spent on assorted PITA prep work for TIG welding, like sanding the weld joint area, is about the same for either material. The exception is fresh (no rust) bare cold rolled/drawn welded seam ms tubing (CREW) since it has no scale/coating on it needing to be sanded off. Hot rolled ms (HREW) has a little thicker scale/coating than DOM ms has (but they are very close to the same), 'moly usually has the least/thinnest amount of scale/coating on it vs either HR or DOM.

Bending the two materials is a mixed bag. The cold rolled/drawn ms is very soft/ductile & super easy to bend with very little spring-back because the material is in effect stress relieved since it's worked/rolled/drawn cold. At times it almost acts like it's too soft/ductile to be use as cage structure material. Both hot rolled & DOM take a lot more effort to bend & have more spring-back (vs cold rolled/drawn) since both HR & some DOM starts out as "hot rolled" base material. The mandrel process does stress relieve DOM a little (from it's original "hot rolled" starting point) making it a little more ductile, but still no where near as soft as the cold rolled material is. And normalized 'moly is somewhere in the middle, it's both "rigid" and ductile (to a point) at the same time. It's not super hard to bend because of the thinner wall & it's ductile properties, but it's "stiffness" can create a decent amount of spring-back.

my car 8.50 cage was done by DMC .... and is all chromoly but what i paid for it and how fast i plan to go lol .......it prob doesnt matter if it was mild steel either though . Only gain i see in my case of combo would be re-sale value might be a lil higher but even then i dont know

Price of steel has gone up over the years , i bet the price for a c/m cage now is even more than it was 4 years ago

I have a ? for you tiggers. If you are building a chassis or whatever.Can you spot it together w/mig and then take it to the TIG shop?

just dont get crazy w the tack welds

bbf-falcon wrote:I have a ? for you tiggers. If you are building a chassis or whatever.Can you spot it together w/mig and then take it to the TIG shop?

Years ago at Logghe, I have seen a moly chassis spotted together with gas welding first but never cold welded with a MIG ... that is a good question for the metallurgist people on here; embrittlement next to the weld spots would tend to scare me.

richter69 wrote:just dont get crazy w the tack welds

^^^^ and put/hide the mig tacks under or behind the the bars, in inconspicuous places. Make where you see the tig welds look better.