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Stainless project: welding & drilling

2K views 23 replies 8 participants last post by  bkubisht 
#1 ·
OK, so I'm getting ready to build something cool out of stainless steel. Let's say a header, since it would be a very similar project.

First, I've got some 3/8" 316L for the flange. How can I cut holes for the ports? Need to be about 1.4" diameter. I don't have access to a cnc machine or plasma cutter. I can buy a titanium drill bit on ebay that goes up to 1 3/8" which is a fine size. Will this drill bit stand up to drilling 5 such holes in my stainless flange? Or is the stainless too hard?

(I wish the flange was only 1/4" thick, but that's all the supply yard had. And I paid through the nose for it, too)

Second, the runners will be made of 16-guage exhaust tubing by cutting & piecing together pre-bent stainless stuff from summit. This is my only project in the forseeable future where I'll need to weld on stainless. Can I just use stainless MIG wire, and 75/25 gas? Or do I NEED a more exotic shielding gas?

(I checked into getting a 2# spool of fluxcore'd stainless, and they guy basically said they don't carry it because it costs SO much, and I shouldn't even ask)

TIA! -Bryan
 
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#2 ·
On the 3/8" stainless, you can cut it with a hole saw and a hand drill. You want a fast feed rate and a VERY slow cutting/rotation speed. I don't know the cutting speed offhand that's appropriate, but it can be done. Just don't sit in one place very long or it will work harden.

I used a HSS hole saw 2 5/8" to cut some 14 gauge stainless on a drill press. The drill press went way too fast for it and work hardened the hell out of the stainless. It took forever! It smoked the hole saw pretty good. This is why you need a SLOW cutting speed.I also did some cutting on a mill using an appropriate speed & feed rate and it went pretty easy.
 
#3 ·
you can buy cored stainless wire, which will work with steel mix, but better with straight co2. Solide ss wires require helium mix or argon depending on the type. I use 308 cored wire for most of my stuff. I also have very good luck with stainless rod, but it will distort the back side of the weld, something you may not want for smooth flow.

Use a ton of cutting fluid for drilling to keep it cool, but it will be a pain. It might be worth it to take the material to a shop with a punch or a cutter to do the flanges.
 
#4 ·
Bandit's got it right on. I've done plenty of SS work and you want to make sure that your hole saw is turning as slow as possible. A fast feed rate is not necessary but rather a steady constant feed with plenty of coolant. You don't want to cut and then lift off again. Once you start cutting keep the pressure on and cut through. One of the most helpful things that we did was to drill a small hole or 2 (1/4" - 3/8) on the diameter of the cut for the chips and coolant to fall through and clear the work. Also works to unplug any teeth in the hole saw. Just remember that 316 is harder to work with than 304. I would definatly suggest hole saw over a drill bit.
 
#5 · (Edited)
Listen to redrangie and liftedzj. I forgot to mention the cutting fluid, but that's very important! It will save your hole saw. I have never drilled a hole on the periphery of the cut, but that sounds like a very good idea and I will definitely try that out next time.

redrangie likes it in the butt :blackflipsoff2:
 
#6 ·
TheBandit said:
Listen to liftedzj. I forgot to mention the cutting fluid, but that's very important! It will save your hole saw. I have never drilled a hole on the periphery of the cut, but that sounds like a very good idea and I will definitely try that out next time.

HEY! I said it first!!!!!

:flipoff2: :flipoff2: :flipoff2:
 
#8 ·
stainless tubing should be welded "cold crowned beads" as per lincoln. the main concern is the HAZ or heat affected zone on the edges of the tubing beside the bead that will cause cracking due to carbide precipitation (if i remember exactly) for the best results (totally smooth inside) purge the tube with argon while welding.
 
#10 ·
WOW, there's a lot of good advice here. I was surprised about you guys endorsing a hole saw. Whenever I've tried to use one on regular 304 it always takes fussing around to keep it cutting through. I guess now I just need to find a hole saw the right size, because I definitely don't want to be resizing the holes with a die grinder. Whatapain.

Handheld drill??? Another surprise. I knew I would need to spin it slow with plenty of pressure so I'd be cutting instead of rubbing and creating heat. But I wouldn't have thought very low RPMs could be maintained while keeping strong pressure on the work. Is the gain here simply that you can rock back and forth so heat doesn't build up as much?

So flux-core SS wire actually also needs shielding gas too? I would never have guessed. Is there some online sources for fcaw ss? There's only one store around here and they don't want to deal in this exotic stuff, and I don't see it on ebay or cyberweld.

I'm guessing that I don't need to worry about the "cold crowned beads" because I was careful to be sure I got the "L" low-carbon type of 316. But I'm no professional welder so correct me if I'm wrong. I don't even know what "cold crowned beads" is. It was never mentioned in my MIG class last year.

Does HSS = High Strength Steel?
 
#11 ·
HSS - High speed steel instead of carbide tipped cutters. I wouldn't suggest a hand drill though. Drill press or a mill. You need to keep the cutting surface tight against the material and that is going to be really hard to do with a hand drill. Also you might stall the drill out. You are going to need to turn the saw at around 60-90 RPM. I don't think most home drill presses turn that slow. I suppose a variable speed hand drill can be kept that slow consistantly.
 
#12 · (Edited)
bkubisht said:
=

So flux-core SS wire actually also needs shielding gas too? I would never have guessed. Is there some online sources for fcaw ss? There's only one store around here and they don't want to deal in this exotic stuff, and I don't see it on ebay or cyberweld.

I'm guessing that I don't need to worry about the "cold crowned beads" because I was careful to be sure I got the "L" low-carbon type of 316. But I'm no professional welder so correct me if I'm wrong. I don't even know what "cold crowned beads" is. It was never mentioned in my MIG class last year.

Does HSS = High Strength Steel?
Flux core means just that. It doesn't nescessarily mean that it will provide all of the shielding for the weld. There are plenty of cored wires that require additional shielding. Most are used for increased heat and penetration.

Buy from the wire from airgas or linweld if they have one close. They will have the wire. Also go to www.lincolnelectric.com or www.esab.com for wire specs and information. Once you figure out the aws classifications of the wire, that's all you need, rather than worrying about what brand of wire you buy. If I remember right, plan on about 15.00-23.00 for the 2lb roll.

As for backpurging, I wouldn't worry about it for a header. As always there is the way the book says, and the field expediant method. If you were worrying about certification level welds, yeah. Somehow, I think your not. If you have a low amp dc machine, you COULD stick it with 308, and be fine. You just have to clean really well, and move real fast. You won't have a stacked or oscillated weld look, but hell, that's what die grinders are for.

One more thing. buy stainless only consumables, or brand new never touched steel ones, and mark them stainless only. You will find that abrasives will finish better if they are designed for stainless. I use gemini brand, and tiger, and do well with both.

j
 
#14 ·
liftedzj said:
HSS - High speed steel instead of carbide tipped cutters. I wouldn't suggest a hand drill though. Drill press or a mill. You need to keep the cutting surface tight against the material and that is going to be really hard to do with a hand drill. Also you might stall the drill out. You are going to need to turn the saw at around 60-90 RPM. I don't think most home drill presses turn that slow. I suppose a variable speed hand drill can be kept that slow consistantly.
Exactly my reason for suggesting a hole saw. Most drill presses will not turn slow enough, especially not the benchtop style that you can get at your local Sears/HomeDepot. A hand drill can maintain slower RPMs, but I agree there's a risk of burning it up and it's not as precise as a drill press.

I have a Hitachi drill that works great for this sorta thing. It has an adjustable stop built into the trigger to steady it at whatever speed you are intersted in. I have used it at really slow speeds many times and have yet to burn it up.

Yes an endmill is the right tool for this job, but since he says he has no access to one, I think the holesaw and hand drill are a good alternative. He runs the risk of burning up both.
 
#16 ·
It's an Intake Manifold

Nope, it's not a header. It's an efi intake manifold for a 4-banger. MC, what would be wrong with stainless headers? If I had to guess, that's what I'd say my thorleys are made of. I chose stainless because I didn't want any problems with rust or corrosion, didn't want to get it coated inside the tubes (pricey), and don't have the equipment or skills to tig aluminum. And bent tubing is easy to get in stainless.

You're right, I'm not going for a welding cert on this. No backpurging, I don't really have the means anyway. I'm a decent welder for a hobbyist, about to buy a MIG and work on this project I've put off for years.

I bid on two bosch bi-metal hole saws today on ebay. So if I wear one out, there's another.

I do have access to a very big full-height drill press at the local auto hobby shop. That's what I planned to use, but of course don't know if it spins slow enough. I'll stop by to check tomorrow, hoping to count 10-15 revs in 10 seconds. Now I'm trying to figure out how to keep the job cool and lubed without making too big of a mess in their machine room. Will a couple cans of WD-40 be OK for cutting oil?
 
#17 ·
bkubisht said:
Will a couple cans of WD-40 be OK for cutting oil?
NO!!!

By some specific cutting fluid, the thicker the viscosity on stainless the better, unless you want to go spend 50.00 bucks for a fountain pump and some lube and a tray to circulate the good stuff.

5.00 in the right cutting fluid will make a big difference.
 
#18 ·
I'm not sure why you wouldn't build the manifold out of steel. It's not subject to any more corrosive abuse than an exhaust manifold and it would be easier to fabricate.

That aside, I had good luck with a moly tap fluid. It was about as thick as gear oil and cost a few bucks. You could probably get something better, but even if you cant it will be lightyears ahead of WD40.
 
#19 · (Edited)
OK, no wd40 then. I've got a bunch of stop-smoke super-high viscosity oil additive that sounds like the perfect thing to use. It pours like honey. It'll put up with the heat, stay in place, etc.

I checked out the drill press today, and the slowest speed is 230rpm. So I'm back to my hand drill.

Exhaust manifolds stay hot enough that water doesn't rust it. And they are protected by carbon buildup. I figured I didn't have that going for me on an intake, and I've never seen an oem intake made of mild steel unless galvanized or otherwise coated. I'm not chroming this thing or anything.

I looked at esab and found this: http://www.esab.com/index.asp?item=27317 . My Hobart 140 is 140 amps, and this wire requires 150. Hopefully it's close enough! I still haven't found it in a 2# spool.
 
#20 ·
Having welded more small bore Sch. 5 304SS with GTAW than I care to think about and also having welded more than a few joints of 18Ga 1” 304SS tubing using 0.025” hard wire, He Tri-mix and a Miller 175 I would take GTAW over GMAW.

If you only have access to a GMAW machine or you are not real confident with GTAW here is what “I” would use:

A 0.035" 308/308L solid filler can be satisfactorily ran as low as ~60A when using a 90%He 7-1/2%Ar 2-1/2%CO2 and short circuit transfer. It will work for 16Ga but not have near the controllability of 0.030" in a butt weld situation.

For what you are doing a 0.030” 308/308L solid filler with a He tri-mix is likely going to be the easiest as well as cheapest method if your gas supplier has no issues with changing out shield gas mixtures and charging you for only the contents used.

If you are new to welding SS especially with short circuit and thin material I would strongly consider using 308LSi filler as the ~0.8% Si content will improve wetting and washing behavior, especially when welding the 304 tubing to the 316L flange.

There are many options for gas shielded metal cored and flux cored filler that will work great with 75/25 or 100% CO2 but finding them in the combination of small diameter (0.035”) and packaging you would need for economy is not likely, nor are they well suited for your usage or machine.

Self shielded 308L flux core (AWS E308LT0-3) is available in 0.035” sized filler but once again finding it in less than 30# spools is going to be a near impossible task, it is insanely expensive, nor are they suited for your usage or machine. As well it is only recommended for the flat and horizontal positions.

Your best bet for filler would be Harris-Welco as they have many different diameters of hard filler and AWS classifications available in 2# and 10# spools. 308LSi is available in 2# spools in 0.025, 0.030, 0.035 and 0.045” from them; as above I would be inclined to use the 0.030” filler

Ballpark guess for a consumer buying this would be $20 for a 2# spool and $60 for a 10# spool of 308LSi hard wire.

You can also get 10# spools of 0.035" 308/308L hard wire from McKAY, INE has 2# spools of 0.030" and 0.035" 308L hard wire available as well, but Harris-Welco filler should be easily found locally or ordered over the Net.
 
#22 · (Edited)
bkubisht said:
Exhaust manifolds stay hot enough that water doesn't rust it. And they are protected by carbon buildup. I figured I didn't have that going for me on an intake, and I've never seen an oem intake made of mild steel unless galvanized or otherwise coated. I'm not chroming this thing or anything.
I know it's not exactly the same as mild steel, but most intake manifolds from the early beginnings of the automobile on up through the 70s were made of cast iron. The manifold on my 30 year old car was cast iron (before I put an aluminum one on) and the intake runners were rust free. I'm curious how the extra carbon in mild steel makes it any more susceptable to rust? :confused:
 
#23 ·
jasonmt said:
There are many options for gas shielded metal cored and flux cored filler that will work great with 75/25 or 100% CO2 but finding them in the combination of small diameter (0.035”) and packaging you would need for economy is not likely, nor are they well suited for your usage or machine.

Self shielded 308L flux core (AWS E308LT0-3) is available in 0.035” sized filler but once again finding it in less than 30# spools is going to be a near impossible task, it is insanely expensive, nor are they suited for your usage or machine. As well it is only recommended for the flat and horizontal positions.

Your best bet for filler would be Harris-Welco as they have many different diameters of hard filler and AWS classifications available in 2# and 10# spools. 308LSi is available in 2# spools in 0.025, 0.030, 0.035 and 0.045” from them; as above I would be inclined to use the 0.030” filler

Ballpark guess for a consumer buying this would be $20 for a 2# spool and $60 for a 10# spool of 308LSi hard wire.

You can also get 10# spools of 0.035" 308/308L hard wire from McKAY, INE has 2# spools of 0.030" and 0.035" 308L hard wire available as well, but Harris-Welco filler should be easily found locally or ordered over the Net.
Linweld carries the 308L (at least they do in denver) in 2#'s in from Harris.

Remember most suppliers like Linweld and Airgas will order special order, and mine doesn't even require pre-pay. Usually takes about 3-5 business days.
 
#24 ·
Thanks for the advice all. Especially JasonMT, I was wondering what I should do about welding different grades of stainless together. Good advice on filler size too, I'm sure I needed that.

Hopefully the local Mom&Pop welding supply will sell me some tri-mix and just refund for what I get back. In the mean time, the hole saws should arrive this weekend and I'll shoot some pics of how it goes.
 
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