Rookie Exhaust Effort

denisducati750

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Well I’ve decided to have a crack at building my own custom exhaust. Rough going with a new MIG and lots of thinking tIme but enjoying the challenge. Tried this 2 into 1 merge bit and feel I can do it - but will re-do tomorrow leaving the cut ends a bit longer so the down pips are better spaced. D
 

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Hey, that’s pretty good Denis! Keep at it and you’ll soon have the knack.

I find watching an experienced welder is mesmerizing and they make it look sooooo easy.

Pete
 
Zat flux core MIG? gotta go gas, just sayn' Design, cutting and fitting looks great!
Um, the welds? not so much, add lots of heat or slow down the feed. Do lots of practice on thin scrap first. You want plenty of heat and penetration. Control melt outs by keeping "on time" short. Weld, stop, let cool till the red goes away looking through the shield, repeat. A much easier process if you aren't constantly chipping slag.
 
Zat flux core MIG? gotta go gas, just sayn' Design, cutting and fitting looks great!
Um, the welds? not so much, add lots of heat or slow down the feed. Do lots of practice on thin scrap first. You want plenty of heat and penetration. Control melt outs by keeping "on time" short. Weld, stop, let cool till the red goes away looking through the shield, repeat. A much easier process if you aren't constantly chipping slag.

Agreed - while it is cheap and appears to be MUCH simpler, the fact is that flux core welding really doesn't work all that well.

I've got a brand new Lincoln MigPak180 rig in the shed just waiting for warmer weather and my danged knee to feel better and then it'll be Pete's Inferno around here as I learn to do this myself. :yikes:
 
Great feedback fellas and appreciated! I’ll only use the MIG very occasionally so wanted to avoid storing a gas bottle. I grabbed a heap of off-cuts yesterday so practice time today. I’d only planned on tack welding the system with a pro mate doing the actual welds. But yesterday it took a very long time to clean away a few racks just so I could break the joint and change the angle so the gas less wire seems to offer plenty of strength for the sorts of little jobs I’ll be doing. Setting up for some practice welds now!
 
I also agree with Gary. First thing i thought was that man needs to ditch the flux core. As for the bottle,when you do get it makes sure you open all the way and dont forget to close it when your done. Dont ask me how I know it will be empty if you dont close the valve when done.
 
I went from flux core to gas and the difference is amazing. But I switched from a harborfreight flux welder to a hobart 140 with c25. Honestly the gas stores fine, an 80 cubic foot bottle lasts me about a year and is only $30 in my area to swap out. The weld quality when going to gas shielding after flux is a "wow I can weld better than I thought" moment.

Keep working at it, I did my merge basically the same way and it works great.
 
Great feedback fellas and appreciated! I’ll only use the MIG very occasionally so wanted to avoid storing a gas bottle. I grabbed a heap of off-cuts yesterday so practice time today. I’d only planned on tack welding the system with a pro mate doing the actual welds. But yesterday it took a very long time to clean away a few racks just so I could break the joint and change the angle so the gas less wire seems to offer plenty of strength for the sorts of little jobs I’ll be doing. Setting up for some practice welds now!
Your welding pro will hate ANY slag left behind by your flux core wire.
 
I've built a number of exhausts and have learned a good bit over the years. I use a TIG welder but have done some stuff with MIG as well. I'd have to agree with the others and recommend getting some shielding gas hooked up. Your welds will come out much cleaner, really is night and day from my personal experience.

Spend a good amount of time cleaning your materials, more important for TIG work but still worth the time no matter the welding process.

I like to chamfer the edges of all my tubes, not sure if it'll make a big difference if you're MIG welding. With TIG and a chamfered edge you can run lower amps and the distortion around your welds will be minimized.

If you can come up with a smaller tight fitting tube to put inside your exhaust tubes during welding it'll act as a heat sink and also prevent tube distortions. Just make sure you can get them out when you're done! I have done some exhausts where I just make little rings to put inside the tube at the junctions and just leave them in. If they're not very thick I don't think it's gonna restrict your system to the point of doing much. I'll even file the edges of the rings so air can move over those little internal bumps smoothly. They also help to hold the tube in place if they fit tightly enough.

I've stopped making my own merge collectors and have always bought my materials from this place: http://www.mandrelbends.com/ I live near there so shipping is cheap and they offer probably the best prices I've seen on tubing/bends/collectors etc...

I prefer to work with stainless cause it looks nice and holds up better. If you play around with it you'll want to back purge the material (fill the inside with gas) to protect your welds. There is a product called SolarFlux specifically designed for welding stainless without back purging, I've had great luck with it so far.

Weld in small amounts at a time, the cooler your material stays the less warping. Sometimes the hardest part is just waiting for things to cool in between welding sessions enough to keep your overall material temperature nice and low.

good luck
 
Yep - great advice! My pro welder has already nearly hit the deck when he saw a demo wd I took out there to show him. But, it cleaned up really well after some time with a heavy wire brush wheel on my bench grinder. Going to check out the gas bottle option after all this feedback. Also finding the MIG I bought doesn’t offer enough in terms of low power - I should have bought one with an adjustable dial instead of a switch offering just a few settings. Thanks guys!
 
Gasless welding - I never had any success until I converted my cheap HF type 45/90Amp welder to DC using a cheap Chinese bridge rectifier, added in some 60,000 uF of capacitors for smoothing and added another tap to the transformer to give approx. 65Amp also. I found you need to buy the expensive fluxcore wire. I currently use SIP at £13 per 450g reel. For this same price you could get two reels of other wire but the quality of the welds drops off rapidly. I believe the Lincoln fluxcore wire is very good but again the cost is higher.

If I had to start again I would probably buy a MIG with gas or a TIG system.
 
Yeah, having an amp adjustment dial is very nice to have. As long as you can get your machine down as low as 30amps or so you should be totally fine doing exhaust and most sheet metal work. I do some bicycle frame building too, and you gotta get 'limbo champion low' in the amp setting to not blow a hole in that stuff.
 
Well I’ve been experimenting and came up with the following thoughts for anyone like me who’s looking for a cheap MIG that’ll do small jobs occasionally. My MIG switch offers 35 as the lowest option for power. I reckon a dial you can turn up and down (and lower than 35) would be a better option. If like me you think a gas-less MIG is a cheap way out - think again because when I looked into adding a bottle, regulator and wire today, that would cost around as much as my MIG did as a ready to go gas-less solution. So I’ve stuffed around a lot with watching You Tube gas-less welding tips, wire speed and the angle I’m holding the torch at and seem to have reduced the splatter, giving me acceptable tack welds. Could be better but will do the job and at least not burning holes.
 
A decent low cost mig set up like a hobart handler 140 or equivalent is going to cost $400 and up, it also comes with a regulator and hose so you just need a bottle at around $200 for an 80cf, a little cheaper for smaller but fills will cost basically the same.

On a budget check hobartweldshop.com they sell factory refurb for a good discount, 2 year warranty, and pretty cheap shipping. Also call around to local welding shops, gas and wire will be much cheaper there than anywhere else.
 
Also, don't be afraid to buy used... I can usually find decent sized bottles for around 100$. If you're lookin' at different machines, I've become a fan of Everlast (higher end Chinese made machines). There are also good deals on machines in the used market. Good luck.
 
My bottle and gas cost me $60 deposit and every refill is $12. An investment in bottle, gas, regulator is not lost. If you eventually get a better welder you can use the same gas do-dads. I bought and am very impressed with my Harbor Freight 220 volt, 170 MIG, less than $160.

Scott
 
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