Aluminum trailer build

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Well, my aluminum pile finally came out from under the snow last weekend. Of course, this is what my yard looked like this morning. But, if it ever warms up enough to work outside I'm going to build another trailer. This one will be for sale, and I want to maximize the value from what material I have, so I've decided that this trailer will be a smaller version of this trailer. It will be 16' long on 2-3500# torflex axles with electric brakes.It will have a tip up beavertail like this trailer has so that you will be able to have the full 16' of flat when needed.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:I will be using as much of the material that I have, rather than what I wish I had, as possible, so some of what I'm going to do will be a little different. I have a 6" I-beam that will be the main rail and a 6" channel that will be the tongue, beaver tail, and front cross member. The rest of the cross members will be from some 1 1/2" schedule 80 pipe that I have. The side rails will be 3" channel with stake pockets. The floor will be this extruded plank.I've used this before and it is very strong and light weight.  I'm going to try to keep this trailer as light as possible and am shooting for about 1,200# finished. We'll see how close I get when It's done. Hopefully I'll start the build next week.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Sounds like a cool build I'm planning my first aluminum trailer now - may hit you up with some questions in a few weeks if you're up for it.Nothing big, likely a 5x9.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Ah ha! Finally someone is making a decent ALUMINUM trailer build!I am super excited to see how this turns out welderj. I hope you keep us up to date with detailed info during the build.
Reply:Oh, nice Volvo as well. You must be an owner operator.
Reply:Originally Posted by Canadian WeldingOh, nice Volvo as well. You must be an owner operator.
Reply:Originally Posted by MinnesotaDaveSounds like a cool build I'm planning my first aluminum trailer now - may hit you up with some questions in a few weeks if you're up for it.Nothing big, likely a 5x9.
Reply:I hope you moved that pile of metal indoors before the 18" of snow hit, spring...........................ya, right!!!!!!!!
Reply:Subscribed.Now I lay me down to sleep, by the bed a Colt I do keep.Should I wake and find you inside, a coroner van is your next ride.
Reply:Well got a little start on the trailer today. Had a couple problems tho. When I was going through my aluminum pile to see what I would use on this trailer I saw the I-beam and channel that I mentioned earlier, but when I went back to start cutting parts I found that the I-beam was 5" rather than 6". The 5" would have worked, but I didn't have enough. Went to my supplier to see if I could get some more but they didn't have any to match either. So I decided to go back to plan "A", which was to build a truss type frame from some 1 1/2" sced. 80 pipe. Here is what I got done after spending most of the day chasing aluminum and welding supplies.The pipes are just under 2" OD, so I went with 2 1/2" long legs which will give me 8" total height when done, with a 6" tall drive over fender. While laying it out I took these picks so you can get an idea of how it will go together. There will be the 2 main rails as normal and a third down the middle. I will run a piece of 1 1/2 x 3/16" flat on top of the pipes so the planks have a flat to sit on. There will also be a 3" channel outer rail. I'm figuring the uprights at about 18-24" spacing and there will be 1/4" flat welded to the outside at the axles and the front where they bend in for the tongue and the rear where they will bend down for the beaver tail.Rather than notching the pipe legs I just flattened them a bit on each end. This give just about the right gap for welding and makes the weld about flat for easier welding. It also makes for less cross section weld on the main pipes. I've done this before and like the way it turns out. When tacking it together I tack the center of the uprights first. Then square it up and tack both fore and aft on the uprights. That keeps it square. Then flip it and weld the backside, flip it and weld the front. You get very little pulling that way. Here is a close-up of how they fit.Going to be a lot of cleanup on this stuff from being stored outside. Not real happy bout that, but stuff happens. Don't know when I'll get back to it again, got planting season on the farm coming up in a week or so. I also need to make another trip to my supplier since I forgot to get a heavy wall 3" tube for the coupler. I have nearly every other size tube that would be heavy enough, but the coupler is 3". I also need to go about 270 miles round trip to pick up some more of the floor plank extrusions. I have about enough to do 2/3 of the floor now.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Here are the basic dimensions. The total length will be 18', 14' + 4' beaver tail. I went 18' rather than 16 because it will make it easier to balance with the load and more versatile. With 16' trailers they can be hard to get large vehicles on without getting too much tongue weight. They can also be hard to get a tractor on since tractors weight is concentrated at the rear wheels, so the can hit the front of a 16' trailer before you have enough tongue weight unless you hold the wheels back which compounds the problem with cars. It will be about 102" total width. The axles will be at 60%. That should keep it so that they can tow it with about any full size suv or pickup with a full load. The fender section will be about 6' long and end at the rear of the flat leaving about 8' of full flat in front. The beaver tail will be 4' long and full width and will hinge up so that if needed they will have 18' flat for things like hay or lumber ect.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Cool stuff!  I like trailers!
Reply:I wrote this up for another forum and thought I would share it here as well. This helps explain why I'm going with the axles I chose and gives some info on how they work in general. I just copied and pasted it here so it's a bit off for this thread.ok, the second installment if your still interested. Thought since rick deere said his suspension was worn out I would go over that area next. There are 3 basic suspension types for small trailers. I won't get into air ride because it's still rare for what most of us use.The first is the double eye type,shown in the first pic. It's the most common, mostly because it's the cheapest. It has an eye on each end of the spring and uses straps at the equaliser.The second is the slipper spring type shown in the second pic. It has an eye in front and a flat in back the just slides on a steel plate.The 3rd is the "torflex" shown in the last pic. It has the spindle mounted on an arm with a square bar on the other end that goes int a tube at a diagonal to the tube. There are 4 rubber ropes, if you will, in each corner and as the load is applied the square bar works against the rubber giving you the spring.There are some definate advantages and disadvantages to each type. I like the torflex the best. It is by far the most durable and has no suspension parts to wear out. I've had them on trailers since about 1985 and have never had one worn out or fail. They also ride better with less bounce than spring type axles. They do not equalise however, which is both good and bad. It's bad because in a tandem application all the weight can and does end up on one axle. This is ok and is expected and they are warranted for double their rated weight so no problem, but some folks are scared by it. This does give some advantages too, such as more forgiving loading. Take for instance a 7-14,000 lb trailer pulled with a 1/2 ton truck. If you do the hook up properly like I described in my last post you will get several advantages. First with light loads and low tongue weights, you will have a front high situation. This will transfer more weight to the rear axle giving a better tongue weight which will help hold down that "tail wagging the dog" thing. Conversely, if you get too much tongue weight you end up with the front down, transfering more weight to the front axle which will help to limit overloading the tow vehicle. Torflex axles do cost more, and add even more to the cost of the trailer by requiring a heavier frame to handle the torsional flexing. This can easily be overcome by the savings in maintenance, especially on high mileage trailers. You cannot however; use torflex axles on a tri-axle trailer. In a tri-axle setup you could end up with all the weight on one axle exceeding the limit if the trailer is fully loaded.My second favorite is the slipper spring type as in the second pic. This is as good as a spring suspension can get and far superior to the double eye. The springs in this type both pull from the front which is much stronger than the double eye type. They also have fewer parts to wear out. If you look at the green circles in the second pic the show the main wear points, the spring bolts at the front of the spring and the equalizer bolt. If there is any movement there they need replacing. Most have plastic bushings in them and don't last too long. If you decide to replace them don't even bother trying to save the bolts, they will be shot anyway, so just torch them off and replace both the bolts and bushings. If you look at the blue circle in the second pic you will see the slipper part of the suspension. If you run a LOT of miles this can wear out too, but it takes a LOT. I've seen a couple that had to be fixed, so if you have this type it won't hurt to keep an eye on it.The last type, and one I never recommend, even tho it is the most popular. It's the most popular because it's the cheapest, it's the cheapest for a reason. If you look at the red arrow in the first pic it shows what my biggest complaint is with the system. In a tandem application, the rear axle pivots on the rear bolt, so the force is pushing back, or compressing the spring. This leads to bent springs. If you get any where near the rated load for this type suspension and hit even a small obstruction, you can end up with a bent spring. This leads to an axle out of alignment and all that causes, worn tires, dog tracking, control issues and worn suspensions. It can be deceiving to to an ammature because they rarely fail completely, you just end up with more arch in the spring. If it's caught it's frequently thought that it's the front spring that bent because it's flatter. They also have more moving parts and they move more than the slipper type so they wear faster. The yellow circles in the first pic show the wear points, the front and rear spring bolts, the center pivot bolt, and the shackle bolts. Same goes here, if there is wear just torch them out and replace all the parts. The bolts are knerled at the head to prevent turning, if you try to reuse them they will just turn on the mounts and destroy the hangers too. NEVER NEVER NEVER, buy or build a trailer with a double eye suspension in a tri-axle setup. The third pic shows why. The center axle is a floater because there is nothing to hold it in place except weight. This allows it to move a lot causing it to go out of alignment. There is nothing that can be done to make it any better either. I've converted a few of those to slipper type suspensions because the customers just couldn't keep tires on the trailers and they pulled very hard. There is no amount of cost savings that would make that worth while to me.If you are getting dog tracking or having tire problems and your suspension is not worn out, check the alignment. I've seen plenty of commercially built trailers come off the line out of alignment. I've had a couple I did myself too. It's not hard to do. The most critical measurement is not off the front of the trailer as most folks think, it's the between the axle measurement that will cause the most problems. In the slipper type that would be the front hanger to center hanger measurement. They should be within an 1/8". For the double eye it's the front and rear hangers that need to be within 1/8". If the front hanger is off from the front of the trailer you will get some dog tracking, but won't get tire wear and handling issues as long as the axle to axle measurements are good.Finally the u-bolts that hold the springs to the axle. These are rarely a problem, but you should keep an eye on them to make sure they stay tight. They rarely come loose unless you've worked with them. The springs have a center bolt that goes into the u-bolt plate and a hole in the axle saddle. This is what holds the axle in alignment. I mention that because if you do hit something it can shear off. Just pushing the axle back in place and tightening the u-bolts is not good enough. You need to make sure that that bolt is in place. I have replaced them with regular bolts and nuts and just ground the heads down to fit on the holes.Well I think I'll stop here for tonight. I hope this helps and answers some questions, and if you have more or comments feel free to ask. If you are finding this helpful please say so and I'll do some more. If not please say that too and I'll quit wasting your time.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Originally Posted by welderjWell got a little start on the trailer today. Had a couple problems tho. When I was going through my aluminum pile to see what I would use on this trailer I saw the I-beam and channel that I mentioned earlier, but when I went back to start cutting parts I found that the I-beam was 5" rather than 6". The 5" would have worked, but I didn't have enough. Went to my supplier to see if I could get some more but they didn't have any to match either. So I decided to go back to plan "A", which was to build a truss type frame from some 1 1/2" sced. 80 pipe. Here is what I got done after spending most of the day chasing aluminum and welding supplies.The pipes are just under 2" OD, so I went with 2 1/2" long legs which will give me 8" total height when done, with a 6" tall drive over fender. While laying it out I took these picks so you can get an idea of how it will go together. There will be the 2 main rails as normal and a third down the middle. I will run a piece of 1 1/2 x 3/16" flat on top of the pipes so the planks have a flat to sit on. There will also be a 3" channel outer rail. I'm figuring the uprights at about 18-24" spacing and there will be 1/4" flat welded to the outside at the axles and the front where they bend in for the tongue and the rear where they will bend down for the beaver tail.Rather than notching the pipe legs I just flattened them a bit on each end. This give just about the right gap for welding and makes the weld about flat for easier welding. It also makes for less cross section weld on the main pipes. I've done this before and like the way it turns out. When tacking it together I tack the center of the uprights first. Then square it up and tack both fore and aft on the uprights. That keeps it square. Then flip it and weld the backside, flip it and weld the front. You get very little pulling that way. Here is a close-up of how they fit.Going to be a lot of cleanup on this stuff from being stored outside. Not real happy bout that, but stuff happens. Don't know when I'll get back to it again, got planting season on the farm coming up in a week or so. I also need to make another trip to my supplier since I forgot to get a heavy wall 3" tube for the coupler. I have nearly every other size tube that would be heavy enough, but the coupler is 3". I also need to go about 270 miles round trip to pick up some more of the floor plank extrusions. I have about enough to do 2/3 of the floor now.
Reply:Originally Posted by zapsterPic # 4???PLEASE don't take this the wrong way...That I DO NOT like.You are going to have a lot to fill and it's really NOT the thing to do especially on a TRAILER!Take my advice NOW..You will save many headaches in the end.Do it right or....you'll see....zap!
Reply:I'm no expert by any means, and I'm sure Zap could educate both of us. But this is how I would do it. Maybe not go so deep on the cope. 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:Remember it's sced. 80 pipe and over1/4" thick. How will I get full pen welds if they fit thst tight? Sent from my SCH-I200 using TapatalkYeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Originally Posted by welderjRemember it's sced. 80 pipe and over1/4" thick. How will I get full pen welds if they fit thst tight? Sent from my SCH-I200 using Tapatalk
Reply:I would lean towards a cope & bevel method, that is just assuming you are going to TIG this trailer. Being this job is out of alum it would be pretty easy to make a coping fixture for a drill press out of a piece of Oak or Hickory to guide a hole saw...  Or buy one so you have it for later..... The two pictures are kinda common sense but, I have seen many pipes/tubes coped the "incorrect" way, but the "correct" way gives you a built-in bevel to weld to.TOOLS AND TOYSSMAW Mid States Inc. "MISSING LINK" 10-150 AMP Buzzer circa 1945ishSMAW Magic Wand 40-60 AMP Suitcase Buzzer circa 1939ishGMAW Hobart 210 IronmanOxy-Propane TorchMany other old and cold goodies"Rusty but Trusty"
Reply:I think my pics and description were a bit misleading. Also I knew this was going to be controversial when I posted it so I should have been more careful to be clear then. I'll be home this afternoon and will do a demo and give a better description of what I intend and why. Then if you still think I need to change it we can discuss it more.Sent from my SCH-I200 using TapatalkYeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Originally Posted by welderjI think my pics and description were a bit misleading. Also I knew this was going to be controversial when I posted it so I should have been more careful to be clear then. I'll be home this afternoon and will do a demo and give a better description of what I intend and why. Then if you still think I need to change it we can discuss it more.Sent from my SCH-I200 using Tapatalk
Reply:Originally Posted by MinnesotaDaveproper cope and then bevel the tube
Reply:Originally Posted by welderjNEVER NEVER NEVER, buy or build a trailer with a double eye suspension in a tri-axle setup. The third pic shows why. The center axle is a floater because there is nothing to hold it in place except weight. This allows it to move a lot causing it to go out of alignment. There is nothing that can be done to make it any better either. I've converted a few of those to slipper type suspensions because the customers just couldn't keep tires on the trailers and they pulled very hard. There is no amount of cost savings that would make that worth while to me.
Reply:Originally Posted by CEPI'm no expert by any means, and I'm sure Zap could educate both of us. But this is how I would do it. Maybe not go so deep on the cope.
Reply:You'll lose a lot of strength if you don't properly cope the joint. you'll be point loading the upper and lower rails, and you're removing the structural benefit of the round tube by squashing the vertical sections. not to mention increasing the load by reducing the surface area.There are no problems. There are only solutions. It's your duty to determine the right one.Hobart Handler 210Airco 225 Amp MSM StingerNice write-up on the pros and cons of the different suspension types.  I would like to add that axle u-bolts w/ all-metal lock nuts are not intended to be reused.  This does not include re-torquing after x-amount of miles or during maintenance.Just for the sake of discussion, I wouldn't say you CAN'T use torsion axles on a triple axle trailer, but you SHOULDN'T.  Some manufacturers call for a drastically reduced axle weight rating in a triple configuration.  To get the weight distribution between the axles right, would severally limit you on the loading and type use of the trailer . . . I say all this to say that it can be done, but again, usually on a trailer with a specific use. Case in point; Where I work we had to build a fleet of trailers designed specifically to haul 200-400bbl oilfield production tanks to site to be set-up.  Due to the diameter of the tanks we had to go with a very low-profile design, and torsion axles fit the bill.  Each trailer had 4 - 8000# torsion axles.  Since the trailers are loaded exactly the same every time and all the company tractor fifth-wheel heights are approximately the same height, we were able to shim each axle (varying vertical heights in relation to the frame-ground) while scaling each axle at the same time (including the drives and steer axle of the tractor) to obtain "balanced" axle loads without overloading any individual axle.  These trailers have been in use for a few years now and tire wear has been excellent on all of them.MikeConstans Fides et IntegritasLincoln Weldanpower 150 ACAirco Aircomatic MIGet CAV II w/ spoolgunMillermatic 30a wirefeeder
Reply:As far as your description on slipper springs I have only seen them with an equalizer in the center and slip plates front and rear utilizing torque arms. The TEE joint design by flattening the tube slightly would work out better if you cut or ground out a little of the sides to close up the gap.Miller xmt304,  Miller S22 p12, Miier Maxstar SD, Miller 252 w 30A, Miller super32p12, Lincoln Ranger 9, Thermal Arc 181I with spoolgun, Hypertherm 10000 ,Smith torches. Esab 161lts miniarc.
Reply:Originally Posted by M J DAs far as your description on slipper springs I have only seen them with an equalizer in the center and slip plates front and rear utilizing torque arms. The TEE joint design by flattening the tube slightly would work out better if you cut or ground out a little of the sides to close up the gap.
Reply:There is nothing in the world wrong with the “crush method”............................. On farm gates and horse round pen panels. Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by zapsterSorry...Guys..Look..If you are going to put in the time to build something like this why not take the time and do it right?If I was to build the same trailer and do it with the tubing coped and put it along side the same trailer with tubing done with the crush method...Even if I did it...what one would you chose?Think about it.That's what puts guys like ZTPaul and others above the rest.Attention to details..small things but in this case BIG things...all add up to the "Holy Crap" that's nice factor...Take this for what it's worth.Stuff like this is what makes you THAT much better....zap!
Reply:I guess it wouldn't be to much different than those trailers with round tubes welded to angle for side rails.
Reply:I'm no welding engineer, and have very little, oh he!! no experience working with aluminum. But two words come to mind, weld volume.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Not sure if it was asked, is this going to be a mig or tig job?I will be getting a gun for my mig some day for the dirty aluminum jobs.
Reply:Every time you turn a corner there will be lateral forces on those truss sections.There are no problems. There are only solutions. It's your duty to determine the right one.Hobart Handler 210Airco 225 Amp MSM Stinger
Reply:Originally Posted by CEPThere is nothing in the world wrong with the “crush method”............................. On farm gates and horse round pen panels.
Reply:Originally Posted by manningAll of the gates I make for my cows have coped joints. The crushed pipe gates bend too easily.
Reply:Originally Posted by CEPI'm no welding engineer, and have very little, oh he!! no experience working with aluminum. But two words come to mind, weld volume.
Reply:Originally Posted by zapsterSorry...Guys..Look..If you are going to put in the time to build something like this why not take the time and do it right?If I was to build the same trailer and do it with the tubing coped and put it along side the same trailer with tubing done with the crush method...Even if I did it...what one would you chose?Think about it.That's what puts guys like ZTPaul and others above the rest.Attention to details..small things but in this case BIG things...all add up to the "Holy Crap" that's nice factor...Take this for what it's worth.Stuff like this is what makes you THAT much better....zap!
Reply:I really don't have a legit argument here with the exception of when you smash crimp the alum tubing ends you add stress risers to the outside of the tube and with little effort you will crack the tube end..Not saying right now but aluminum don't like being hit with a hammer or put in a press to shape it and in some cases even a little bend here and there will result in fractures in the material..If you were building a fence then I would not have even commented in this thread.But something being bounced around going over the road this is the last thing that I would do personally.Do what you want.Maybe it will...Maybe it won't...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by welderjHow will the weld volume differ either way? The circumference should be the same round or oval, but I'm no math whiz.
Reply:Originally Posted by ThorsHammerThe cross section in 1 direction will be the same if it were a flat plain in which you are welding. But with a coped weld the distance of which you're welding is longer than it would be if it were a flat plain.Beyond the stress risers indicated  by zap, you're argument of more fore/aft resistance is moot because the upper and lower tubes should be receiving stress in the same amount. because in order for one to bend, or stretch the other would have to do the same. A flat channel or Angle Iron or I beam the flat is better because it's one consistent plain throughout the full structure of the component. The forces are spread over the full length of the structure. Not isolated in the risers of the truss. The flanges in an I beam or Channel help prevent lateral twist and collapse of the frame member equally over the entire length of the frame section. You'll also notice that the flanges are almost always thicker than the web. and that web is a located at the same point in the channel and I beam. with your system, if you cope all the vertical sections in exactly the same way you'd have an even lateral balance to the load. With the squished tubes you'll never be able to get a 100% consistent location of the verticals because each section of tube will deform differently under the load. Channel, I-beam, square tubing, would all be better choices. and a lot less work.
Reply:welderj if you do go with flatbar, that would fall in the same design category as a bar joist truss. Which are only strong in two directions, They need lateral load support too.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:With 90 degree joints like this...how hard is it really to just use a hole saw and cope the pipe? I'm new here, and definitely no welder, but a lot of friends have built cars/trucks and I just don't see the point in hammering something to "work".
Reply:Originally Posted by CEPwelderj if you do go with flatbar, that would fall in the same design category as a bar joist truss. Which are only strong in two directions, They need lateral load support too.
Reply:Originally Posted by StoppedDownWith 90 degree joints like this...how hard is it really to just use a hole saw and cope the pipe?
Reply:Originally Posted by CEPOn aluminum it's a piece of cake to cope. This is steel square tube on a compound angle.
Reply:Originally Posted by welderjI'm not seeing the problem either way.
Reply:Not only do you get more weld area by coping, you also get a 3 dimensional attachment vs a 2 dimensional (planar) attachment.GravelThe difference between theory and practice is that in theory there is no difference.
Reply:Coped, flatbar, crushed, smashed or bashed whatever you want to call it is the least concern. The big problem is to keep the rail straight without warping at every riser section. Channel would be a much better choice.Miller xmt304,  Miller S22 p12, Miier Maxstar SD, Miller 252 w 30A, Miller super32p12, Lincoln Ranger 9, Thermal Arc 181I with spoolgun, Hypertherm 10000 ,Smith torches. Esab 161lts miniarc.
Reply:I believe that what Zap was saying is the to cope the joints displays more craftsmanship and attention to detail.  It will produce a better fit up and more professional final product.  People will look at the detail of the coped joint and know that it was done by someone that took their time to do it correctly and cared about the finished appearance of the job