Cutting angles for welding

[Rch]

I'm getting into welding having supplemented my Lincoln 225A arc welder with a Lincoln Power MIG 200. Cutting the right angle so things join up nicely is part and parcel to a nice job. I have a metal cutting bandsaw and a new Milwaukee $160 chopsaw. Both are pretty clunky for cutting angles; the chop saw vise has to be taken off and slid back and forth depending on the angle, width & size of the stock being cut. The bandsaw ( it must be 40 yrs old, a "Cummins") is hardly better with an admittedly buggered-up vise, but long or wide pieces are a problem.
I see these $300 saws for cutting wood trim were the saw tilts, they have a serious table for angles also and the blade assembly even slide in and out to accomadate wider pieces. Can you put a metal cutting blade on one of these or is there an equivalent for cutting metal that is set -up the same ?

 

[Darren]

If you'e cutting 20' pieces of angle you'll need some sort of support besides the saw itself. Otherwise that long end hanging out will make things awkward.

Unless you're cutting really large angles (greater than 2" or 3") the small bandsaws with a bimetal blade do a good job.

The vise on those is rudimentary but you can still get the right angle for the cut. A test cut with some scrap and checking with a combination square will ensure your setup is dead on.

If you're looking at a chop saw, see if you can mount a metal cutting wheel in the machine. The key point is to make sure the saw is designed to cut metal safely.

 

[Rch]

Darren, I have a support stand and your right, you need something to support those long ends. The ability to cut two angles at once would be mighty handy when you get into angular bracing etc.

 

[oldgrizzlybear]

Many of the wood miter saws have plastic inserts. The heat of cutting steel can melt this. I know from experience.

Larry

 

[kyoders]

Rch,

Be careful with a saw designed for cutting wood. Make sure the blade speed of the saw is appropriate for the blade you will be putting in. Most woodworking blades are designed to run at higher RPM than metal cutting blades.

Most of the big-name manufacturers have come out with a new breed of saw designed for cutting metal. They look like ordinary woodworking miter saws, but they have some new carbide blade that makes them able to cut most metals. The saws are pricey ($400+), but what I've read of them makes them sound like a good investment for somebody cutting metal. The cut is supposed to be so clean that it drastically cuts down on grinding/cleanup, and the blade is supposed to last quite a while. I don't have model numbers, but I know that Dewalt and Bosch both make ones, and I would assume the other manufacturers do now, too.

Kevin

 

[crb478]

For the most part the bearings and motors in wood working tools will not hold up to cutting metal for any lenght of time. The plastic parts mentioned eariler will also melt. This is one time it pays to buy the right tool the first time.

 

[Tractors4u]

If the bearings in the bandsaw are still good I would work on that vice and use the saw. I get great cuts with my Harbor Freight bandsaw.

 

[wroughtn_harv]

I have two chop saws at the shop. One is set at ninety degrees permanently. The other is in another stand and it is locked in at a near perfect forty five. I say near perfect because I've got to readjust it. The first saw I locked in on that stand at a forty five I got perfect first time. I could cut pieces and put them together and now worry about using a square, it was that close. But the saw died and the new one is always a degree or so off even after multiple adjustments.

In the field I use a portaband. I have the big Milwaulkee that HD and Lowes sell. It sucks. It's in the shop more'n it's out. The same with the smaller Milwaulkee. Of course someone stole it so I replaced it with a Porter Cable and it hasn't been to the shop after a hard year's work.

Seriously, I bought an extra portaband because the one was always in the shop. It ended up that I'd put when one in when I'd get one out. Then I got the Porter Cable. It's a hoss.

A portaband is invaluable on the job. They will do tons more than folks give them credit for let me tell you. I even use it to cope pipe.

All you have to do is lay a straight edge across the pipe. That gives you an idea of how deep the cope cut should be. You then lay the portaband at an angle just short of that distance and cut one side and then the other. A test fit will show you need to hit the belly of the cut with a grinder lightly.

I did one the other day on a job to show a welder that he didn't need to always drag out his torch to cope pipe. He looked at the finished cope and told me that was why my welds looked good. It was because I got such a good fit first. Hmmmmmmmmmmmmmmmmmmmm he's smarter than I thought.

Seriously, it's a good thing to practice and use when you're welding pipe together. And with the portaband--grinder method you don't have sparks quite so hot/w3tcompact/icons/laugh.gif as you do with a torch./w3tcompact/icons/laugh.gif

 

[gmason]

I recently purchased a Dewalt DW872 metal chop saw with a carbide 70t blade and not a abrasive wheel. I love this tool. I can make cuts in 1/10th the time it used to take. There's marks on the saw table for 90 and 45 cuts to help line the fence up. Everything except the blade guard is metal on it.

I've cut everything from pipe to 9" flat bar with ease and with few sparks.

gary

 

[Hoeman00]

Can you put a metal cutting blade on one of these or is there an equivalent for cutting metal that is set -up the same ?
No, I wouldn't put an abrasive blade on a power
miterbox.
Dewalt DW872 and others make a metal cutter that has
a carbide tipped saw blade. (these run at a low RPM)

 

[Rch]

Harv et al, I looked up the Porter Cable portable band saws on the net.<A target="_blank" HREF=http://portercable.com/cgi-bin/products.cgi?method=bytype&prod_id=METAL_CUTTING>http://portercable.com/cgi-bin/products.cgi?method=bytype&prod_id=METAL_CUTTING</A> I see 2 versions. I didn't even know there was such an animal. From looking at the picture I'm unsure if you can just cut off ends or can you cut a longer piece in the middle. Also how easy is it to cut a 45 degree angle exactlly? Also, what do they go for? Is a carbide chop saw a big improvement over the abrasive blade?
Brent, for sure I'm going to improve my band saw vise with a jig to cut a 45 degree angle.
It seems a power miter saw for steel would have a niche. Obviously, adapting a wood one is problematic.

 

[Egon]

I have used a reciprocating saw with metal cutting blade. It seems to do the job but may be hard to get a double angle cut started corectly.

Egon

 

[Anonymous Poster]

A couple of years ago we bought the top-of-the-line Milwaukee SAWZALL and I am AMAZED at the capabilities of this tool! I should have had one YEARS ago. It saws pipe, both mild steel and other materials, and is a super tool for cutting large diameter PVC. I haven't tried it because I'm pretty good with a torch, but I suppose I could "fish-mouth" a pipe with it if I needed to.....especially smaller diameters. I'm used to working with 6-8-10-12" diameter piping so I habitually use my GAS HATCHET for that kind of stuff.

 

[wroughtn_harv]

Morning Ray,

<A target="_blank" HREF=http://portercable.com/cgi-bin/products.cgi?method=byid&prod_id=725>This</A> is the one I've got and love. I paid two fifty plus tax and license if I remember right.

Btw, I have a deep throat Milwaulkee fresh out of the shop, not even plugged in since it got back, two hundred dollars. That's a hundred off what Lowes and HD want for it. I'll had a hundred to that and get me the deep throat Porter Cable.

There is some skill involved in operating a portaband. That comes with practice. I've gotten pretty lucky over the years at making straight cuts. Luck comes with even more practice.

A funny story, sorry.

I'm a competitive sort. An example would be when I was a cable splicer at the telephone company all the splicers made a big deal out of cutting pennys with their electrician scissors. I of course had to do it faster, just my nature. Then one day a big old lineman cut a quarter in half just cause he could to show me something I guess. Ever since then when a newbie would show how he could cut a penney I'd do him a quarter. I like to say I didn't know I could do it until I saw a lineman do it. And anything a lineman can do I can do, better./w3tcompact/icons/laugh.gif

Well, I heard a story some years ago about a french canadian fitter that couldn't read a tape measure but he was the best fitter to be found.

Ever since then when I'm fitting things up I try to avoid using a tape. I look at it and then try to make the cut. I've had some successes. But there have been some failures, we don't talk about them.

The point being that when you start cutting angles and doing stuff like coping pipe don't be afraid to trust your eye and instinct. One good thing about working with steel is you can fix a mistake and you're the only one that will know. I do it all the time./w3tcompact/icons/laugh.gif

But remember, it's a mistake if you catch it. It's a screw up if you don't.

 

[Egon]

Just add a pipe strecher to your tool supply and the misses can all be redone.

Egon

 

[Egon]

Do you use a jig for holding and moving the torch when you bevel pipe ends?

Egon

 

[Anonymous Poster]

There is a regular machine for bevel cutting the ends of pipe. It is a sort of clamp-around arrangement with the torch on a circumferential chain track. They do have a tendency to "fish-mouth" sometimes....especially on used and not-so-round pipe. We are talking diameters 14" and up. The little stuff is faster to do with a wrap-a-round; a chalk; and a steady hand on the Victor Journeyman No. 200 torch with number 00 tip.
You cut the pipe with the torch laying less-than-normal to the surface of the pipe and pointing toward the scrap end, and as soon as the piece drops off you beat the end of the pipe with a 24 OZ. ball peen....I prefer a VAUGHN...........hammer to establish a small flat area on the butt joint.

 

[wroughtn_harv]

For smaller pipe, two inch and smaller, I have mechanical knotchers. I have a Vogt that cuts two inch (2 3/8) schedule forty so fine. A weldor bud says it leaves a joint that even Ray Charles couldn't mess us welding.

Williams Low Bucks makes a mechanical knotcher that I've got set up for one inch, one and a quarter inch, and one and a half inch pipe.

The Vogt is much nicer a machine. But it cost four times what the Williams does but is worth it.

When I'm doing production knotching (coping) like I will today or tomorrow I use the plasma torch and a sure-fit guide because it's two and a half inch pipe. On pipe that's larger than that I usually make a sure-fit type guide myself from the next larger size of pipe than I'm cutting. I have found they pay for themselves if there's more than twenty cuts usually. Less than that I use the wrap around method or even the old guesstimator.

The only problem with the guesstimator is I've found it's really sensitive to moon--earth movements. When they move it messes up my wife's whacky adjustment which has a definate affect on me. Funny how that works.

 

[Egon]

Right on. The jigs get handy when the pipe thicness increases.

Egon

 

[Ken Kegris]

I have a evolution 14 inch cold cut saw 1400 RPM 300.00 new haven't changed the blade and bought it new in 2004 before retirement. Very little edge very little heat, lots of sparks and throws shavings all around the shop. I also have a band saw 6 inch and between the two along with the plasma cutter I haven't used the torch in years. I use the torch for cutting stuff like a tooth off a cutting edge where i have a lot of weld to skin away. Haven't done none now for years. I am getting to the point if I cant get it at my level or get it on the bench I don't want to do it.