I have been doing a little research on this and it seems like as long as you prep the pieces properly and get a good strong weld using a MIG to put together a turbo manifold is fine. Now the one thing i cant seem to find an answer for is how much grinding down the weld smooth would hurt the strength. I have been thinking of picking up a simple MIG for light jobs like the manifold, IC piping, exhaust work etc as im going to be starting my turbo buildup soon. Most likely I will be using mild steel/aluminized as im gonna have every pipe either black powder coated or heat resistant black finish. So would it be ok to grind down the welds on the manifold if i get a good strong weld and what recomendations would you have if im going to do this? Also what are some decent specs for a MIG thats not to pricey and will work for the jobs im thinking of doing.

Thanks in advance

 

Depends on what you mean by "prep". Here is a quick image I threw together:



The top row shows your basic MIG butt weld. Most MIG welders that you and I use do not have the power to penetrate all the way through SCH10 steel, and you end up with a open back to the weld. This will probably hold up fine, but look what happens if you then grind the weld down... You lose all of your strength and the manifold will crack. This is what happened to my first manifolds.

The second row shows a high-amperage MIG or TIG weld. Full penetration, and grinding down the weld is fine.

Third row is what I have learned to do now in order to get strong manifolds out of my 110V MIG welder. If you grind the edges of the weld area down like this, the same crappy penetration will get you a strong manifold. Sometimes It might take 2 or 3 passes to get the bead in there, but it is worth it. This weld can also be ground smooth.

 

Awesome diagram, i was thinking the best way would be like you've shown in the picture with grinding down the edges at an angle and welding it that way and grinding it down. Do you have any pics of a manifold you did with this technique? This gives me some hope for getting a mig welder and building my own manifold and not having alot of "slop" making the mani look ugly .

 

^ thats exactly why the schedule 40 stuff comes pre cut with angles like that. Makes it a lot easier to weld.

 

As does the SCH10 stuff. However you have to grind the angle back on after you have cut the pieces for the manifold. I also think the original bevel is too small to get a bead all the way to the bottom of the butt weld.

 

Are you guys butting the beveled edges together? If so then id suggest taking a piece of wire as a gauge to space the pipes apart. This will ensure FULL penetration and allow you to do 2 passes on top of eachother without the weld being too tall. Ive also found that doing this will allow you to weld a little colder with less wire speed...thus slowing things down and giving you better control over the pool. This is just something that i do...alot of peoploe dont do it but its what i prefer

Also...dont forget to prep the inside of the pipe. When welding where youre gonna get 100% penetration its easy to pull trash from the bottom of the weld to the top. I see this step skipped alot and its actually a pretty important one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sCeRaXn &raquo;</TD></TR><TR><TD CLASS="quote">Are you guys butting the beveled edges together? If so then id suggest taking a piece of wire as a gauge to space the pipes apart. This will ensure FULL penetration and allow you to do 2 passes on top of eachother without the weld being too tall. Ive also found that doing this will allow you to weld a little colder with less wire speed...thus slowing things down and giving you better control over the pool. This is just something that i do...alot of peoploe dont do it but its what i prefer

Also...dont forget to prep the inside of the pipe. When welding where youre gonna get 100% penetration its easy to pull trash from the bottom of the weld to the top. I see this step skipped alot and its actually a pretty important one.</TD></TR></TABLE>

good tips, what welder would you guys recommend for light duty jobs with only 110V available?

 

I've got the Lincoln SP135 and it's been good to me.

 

how much you pay for it? is it electric or electric/gas?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stealthmode62 &raquo;</TD></TR><TR><TD CLASS="quote"> I've got the Lincoln SP135 and it's been good to me. </TD></TR></TABLE>

same here. I love that welder. I run gas and that welder has done some terrific jobs. I can't complain from 110.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by snoochtodanooch &raquo;</TD></TR><TR><TD CLASS="quote">same here. I love that welder. I run gas and that welder has done some terrific jobs. I can't complain from 110. </TD></TR></TABLE>

any pics of the stuff you've done?

 

I have built tons of turbo manifolds with a lincoln 135. works great

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch &raquo;</TD></TR><TR><TD CLASS="quote">I have built tons of turbo manifolds with a lincoln 135. works great </TD></TR></TABLE>

well ive seen your work and it definitely speaks for itself, do you think grinding down the welds is a bad idea ?

 

ya dont grind them. i hate that.

 

I use the Clarke MIG130E. I love it, and I gather it is similar to the Lincoln unit.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch &raquo;</TD></TR><TR><TD CLASS="quote">ya dont grind them. i hate that.</TD></TR></TABLE>

why dont you like the thought of grinding down mig welds? I just think it would look alot cleaner if i take my time smoothing it out and when its coated it will look really good.

 

Its just a big waste of time for me. Also i always think people are hiding their shitty welds if they grind them down and fill and little hole or whatever. kinda like how you cant grind welds on a cage so it can be inspected. Its like a 'badge of quality' type of thing.

 

i agree. Thats why i never really liked cannondale bicycles. They grind EVERY weld.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch &raquo;</TD></TR><TR><TD CLASS="quote">Its just a big waste of time for me. Also i always think people are hiding their shitty welds if they grind them down and fill and little hole or whatever. kinda like how you cant grind welds on a cage so it can be inspected. Its like a 'badge of quality' type of thing.</TD></TR></TABLE>

Exactly!

Leave the welds alone, or just tack it up yourself and bring it to someone to have it fully tig welded..

 

use no-fluxes wire and a lot of gas. it will burn all the impurities out of the welders