Coping pipe with a chop saw

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I had this brilliant idea the other day:  If you cut a round pipe at an angle, then you automatically get a round cut.  What if I cut the pipe from both sides an make an automatically saddled pipe?Then I remember reading something about that on this forum in the past, and I just didn't know what I was reading.  OK, I'm a little slow here.Can anyone tell me if there is an angle that I could cut pipe with a chop saw and get a properly coped end (assuming I'm going to join it to the same size pipe)?
Reply:if you cut it at 45 you get what you want for a 90 degree T joint.Hey, any cylinder cut at any angle technically cuts an ELIPSE.   a circle is an Elipse of = radii.  :Pregardless the math jargon, 45 is what you want for the 90 degree joint coping job.I does cut the outer skin of the pipe appropriately... however it does not treat the inner surface technically properly for a cope.   this is most of why you dont have saw coped end come to points, but flats.  it negates much of the problem.     usually close enough for welding.   actually better since you can get a better fillet.Last edited by dsergison; 09-04-2013 at 02:56 PM.
Reply:Someone posted this years ago on one of these forums. I saved it, but never tried it, so I have no idea if it works or not. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:http://weldingweb.com/vbb/showthread.php?p=24813#post248132 cuts with a chop saw, then minimal grinding on the inside yeilds a tight fit.Hobbyist - At what point is a "hobby" out-of-control?
Reply:There are a couple of chop saw coping calculators online. Mr Google can generally turn them up for you. It will give you angles and depth of cut for just about any Joint angle or size pipe.
Reply:Thanks, that's exactly what I'm looking for.  Good pics on the thread.  I played a little with this idea enough to guess that it wasn't probably exactly a 45 degree angle.  I also figured that the thickness of the pipe would make a big difference.  I also had a dickens of a time getting my cuts to line up perfectly and figured a jig would be in order if I were going to do a lot of these.  Cut the pipe, turn it over 180 degrees and repeat the cut.  But what is 180 degrees exactly?  That's what the jig would help with.  It would be an alignment jig of some sort.
Reply:I usually clamp/tack on a piece of flat stock so that I can put a level on it, rotate, and re-level.
Reply:You could use a centering head to mark your pipe, then just flip it 180 degrees.  I've seen the chop saw coping thing tried, it works decent on thin wall tubing I thought, but wasn't really impressed on regular wall pipe.  It's close enough that you can put a bead in with 1/8" 6010 or 7010, IF you can handle a gap.  I prefer to just saddle it with a torch myself.  I'm working on a pipe fence right now, I've had my chop saw sitting on my rig for a week now and havn't even plugged it in.  Which, I'm using a beveling machine for my straight cuts, but that's just me...  This is the most 2" pipe i've welded in YEARS, and it's really been good practice.  I'm a lot more used to 6" up to 24" pipe, have never messed with smaller pipe much.-------------------------Chemetron AC/DC 300 HFSnap-On MM300L Lincoln SP140 Lincoln AC/DC 225g Lincoln SA200 Lincoln SA200 Miller Bobcat 225GVictor torchesH&M and Mathey beveling machinesMcElroy Plastic pipe fusion
Reply:Most of what I work on is 2" pipe.  That's what we have lying around.  It's harder to cut, harder to grind and I'm just not that good.  I'll spend 30 minutes for each end of the pipe and end up with good results, but my hands will be really tired from grinding.  The plasma cutter makes things a little better.  I've got some templates for coping pipe online and they help.  It just seemed to me that whenever I start a project that uses the pipe, there will be a lot of fit ups involved and I kind of dread it (I've never been one to do well with practice).  I'm always looking for an easier way.  Sometimes I get burned.  But, advice from experts keeps me out of a lot of trouble and I'll take all I can get.  I will I could just plug an SD card in my ear and download the info I need.  But, skill requires practice.....    Seems like I can't get away from that.
Reply:If you do a lot of 2" saddles, buy or fab up a marking tool.  All it is, is a short piece of pipe that is just  enough larger than your pipe you want to mark that it will fit around it.  One end is cut and ground to saddle perfectly to the pipe you want to T into, the other end is cut square.  then it is split into two halves with a hinge on one side.  It's as simple as placing it around the pipe you want to saddle (or cope, whatever term you use), mark the contour with your soapstone and then cut.  I cut with a torch.  I can mark, cut and cleanup with a grinder in just a few minutes with this method.  You can buy these for around $20 for the cheaper ones.  I just built one with a scrap piece of pipe and a $4.00 hinge I bought at Lowes.  I'm about to make another one for 1 7/8" pipe tomorrow.  The fence I've been working on, I'm using 2 3/8" OD pipe for line posts and top rail, 3 1/2" OD for corner post, then it gets a middle rail and a gate made out of 1 7/8" OD.  For the 2 3/8" to 3 1/2"  at the corners, I've just been grinding a little bit of a saddle, then I can put a bead in it with 5/32" 8010.  My hand cut saddles on the 2 3/8 to 2 3/8 fit close enough that when I started  I was running a bead in them with 3/32 5P+, buffing then capping with 1/8" 7010 HYP.  It worked good, and if I had my SA200 on the truck with a remote, I would keep doing it that way, but instead I have a Bobcat, and got tired of going to the truck to change heat, so I just turned it up a little higher and just burning 1/8 7010 HYP in for the bead now.  It's just fence...  I still don't like how the Bobcat welds downhill, but I have gotten halfway decent using it.  I still wouldn't try to test with it, but it's managable.  Ready to get one of my SA200's going again though...-------------------------Chemetron AC/DC 300 HFSnap-On MM300L Lincoln SP140 Lincoln AC/DC 225g Lincoln SA200 Lincoln SA200 Miller Bobcat 225GVictor torchesH&M and Mathey beveling machinesMcElroy Plastic pipe fusion
Reply:Now that you mention it, I have a couple of marking tools that you are describing.  They're not the right size for the pipe that I usually weld with, but have a lot of different configurations that I have not considered before.  I was just printing out templates and marking them on a stiffer material, cutting them out and then just using that.  But these were all the curved end of the tool.  It didn't occur to me to copy the straight line slots that they have.  These are nice tools to have on hand, but I couldn't afford to have one for each sized, and I'm not skilled enough to make my own like yours.  I do have a good deal of paper backed aluminum sheets that I can cut with a good pair of scissors or shears.  Typically in the past I have used plastic pint bottles as material for the marking tools.You mentioned a centering head that I could use to mark the pipe with.  Could you describe this tool.  This sounds like the direction I would like to go.I also have a lot of fencing materials left over and would like to make some extra gates, but am having a time welding on stuff this thin.  I have an SA200 available, but this will blow through the pipe with my limited knowledge.  I am a newbie and don't recognize the rods you have mentioned above.I just had a semi-emergency and needed a gate to cross my driveway and built one out of line posts and top rail.  There were 24 pieces all together in this 19 foot long gate.  I used clamps since I didn't have time to learn any welding techniques for it.  Now I have some time.
Reply:There was some good threads on some of the 4x4 forums about coping with the chop saw.  I think pirate 4x4 was one of them.
Reply:This is a centering head:-------------------------Chemetron AC/DC 300 HFSnap-On MM300L Lincoln SP140 Lincoln AC/DC 225g Lincoln SA200 Lincoln SA200 Miller Bobcat 225GVictor torchesH&M and Mathey beveling machinesMcElroy Plastic pipe fusion
Reply:Really, you would probably be surprised how easy it is to make one of these hinged templates.  I just freehand marked and torch cut the saddle end, ground until I had a perfect fit, split it lenghwise on one side with the torch, welded the hinge on over the split, then split it again 180 degrees from first split.  I planned on making one for the 1 1/2" pipe today for the middle rail, BUT we don't have any 1 1/2" pipe... So I'm gonna use 2" for the middle rail also.The 10 series rods I'm referring to above are basically downhill DC pipeline rods.  6010 is the old original 5P, (I prefer the gray 5P+ to the original red 5P)  7010 is also referred to as HYP rod, and the 8010 is basically just the 80,000 pound tensile version.  The 6010 is basically the DC version of the 6011 AC rod (which I absolutely hate for some reason).-------------------------Chemetron AC/DC 300 HFSnap-On MM300L Lincoln SP140 Lincoln AC/DC 225g Lincoln SA200 Lincoln SA200 Miller Bobcat 225GVictor torchesH&M and Mathey beveling machinesMcElroy Plastic pipe fusion
Reply:Thanks.  Seems to me, the more I get into welding, the more I find that welders have a specific rod that is their least favorite.  Mine is 6013 - I'll get inclusions every time I touch one of these.  Most of my problems though, are caused by a lack of practice.  I should just stick to a rod that I'm good with or spend a whole lot of hours with each rod.  I keep thinking I can get away with taking shortcuts.  Sometimes I do, and if I don't, then I've learned something new.  The only rods I have available to me locally are the most commonly used ones (I suppose):  6010, 6011, 6013, 7014 and 7018.  There are also some SS rods around, but the only one I've used is a 309 (is that number right, I've slept since then).If you are using the centering head and mark the pipe, how do you know when you have reached exactly 180 degrees when you flip the pipe?  In the past I have just eyeballed a mark with a soapstone on each side and then used a level to get the marks horizontal, made my cut, flipped the pipe, leveled again and cut again.
Reply:Just flip the level vial 180 degrees, and find the previous punch mark with the punch pin.  Or any degree in between.  I built the double gate today out of 1 1/2" pipe (1 7/8" OD)  and on it I just marked each end into quarters (roughly by eyeball), measured back 3/4" on the top and bottom mark on each, and freehand marked a "saddle" line toward the side marks.  Cut with the torch, cleaned up with grinder and it was close enough to put a bead in with 3/32" 5P+.  It just takes practice.  And It's been a REALLY long time since I've fabbed anything with small pipe.I think my thing with my welding rod preference, is I started learning how to weld when I was pretty young.  We had a Lincoln 225 "crackerbox" in the shop, but what I really learned on was an SA200 in our old welding rig.  So it was the SA200 with 6010, 7010 and 7018..  The crackerbox was just used for really small repairs in the shop, anything bigger was either welded outside, or drag the 200 leads in the shop and burn some rod...  I've ran a little stainless rod, but mainly just putting our name or the serial number on equipment.  My dad was a pretty decent welder in his own right, but growing up on pipelines I was very fortunate to be around some really great rig welders, so it's kinda what I know.  I would argue that we had 2 of the best old time tie-in men in the business back in the day, and they were both willing to teach me anything I wanted to know.  I learned things that you can't find in books or schools.  It was pretty funny (and sad) in 1990 I was 18 yrs old, and figuring angles and cutting down 3R 24" fittings for "professional" welders that didn't have a clue how to do it.  Our other welders that I learned from were on another job out of town for us, so we had some temporary welders on the big job.  I was supposed to be running the job when dad was somewhere else, and running the trackhoe.  Dad pulled up and I'm back beveling a 45 that I had laid out and cut down to the required angle.  He was kinda pissed, not at me, but at the fact that I had to quit what I was doing to do that.  He tried to get me to put a rig together and test back then, but I was young and would rather sit on equipment than lay in mud or sweat my *** off...-------------------------Chemetron AC/DC 300 HFSnap-On MM300L Lincoln SP140 Lincoln AC/DC 225g Lincoln SA200 Lincoln SA200 Miller Bobcat 225GVictor torchesH&M and Mathey beveling machinesMcElroy Plastic pipe fusion
Reply:Didn't see the level in the marking tool.  This makes much more sense.Good memories.  It's good to grow up around people who care.I started my learning on an SA200, but the throttle control doesn't work so it runs at full speed all the time.  With the cost of gas I find myself thinking more about the welder than what I'm doing and it's harder to learn.  So, I got a cheap crackerbox that I have been playing with.  So far, so good.  It's 110/220, so I can use it anywhere there is an outlet, DC, stick and TIG.  This will give me a chance to learn TIG (as soon as I get some argon).