Need help with cutting angles!!

admin

So I'm new here and to the welding and fabrication world. I recently made a plate bumper the the angles I had kicked my azz.. I already have it done but I want to learn how to measure and cut even angles like this. Any insight will hell and be appreciated!! my plan was to have all the angles be even.  this one shows how the edges don't match up, I'd like so this didn't happenSent from my XT907 using Tapatalk
Reply:I am also intested, going to start a project like this soon and curious to any tips or scrects.  My plan is to do it out of cardboard and wood to hopefully get the angles right before I cut the metal.  How did you design ths one?
Reply:As for how to learn what angles to use...that's all geometry and trigonometry.  If you're not up to speed in both of those, pick up the "Geometry: A Self-Teaching Guide" and a self-teaching guide for trigonometry.  As for marking and laying out the angles, I'd recommend using a vernier bevel protractor (you can find one for a pretty good price on ebay).  For cutting, I'd recommend just a 4.5" angle grinder with a thin cutting disk on it.  A cad program also helps to lay out the design and figure out the angles, but it's not a substitute for knowing your geometry and trig...it just makes it easier to see what the angles will look like before you start cutting metal.--Wintermute"No man's knowledge here can go beyond his experience." - John Lockewww.improvised-engineering.comManufacturer Agnostic:Blood----------Sweat---------Tears----|------------------|----------------|----Lincoln Red, Miller Blue, Esab Yellow
Reply:Originally Posted by wintermuteAs for how to learn what angles to use...that's all geometry and trigonometry.  If you're not up to speed in both of those, pick up the "Geometry: A Self-Teaching Guide" and a self-teaching guide for trigonometry.  As for marking and laying out the angles, I'd recommend using a vernier bevel protractor (you can find one for a pretty good price on ebay).  For cutting, I'd recommend just a 4.5" angle grinder with a thin cutting disk on it.  A cad program also helps to lay out the design and figure out the angles, but it's not a substitute for knowing your geometry and trig...it just makes it easier to see what the angles will look like before you start cutting metal.--Wintermute
Reply:If you know the angle total to lay out, it's easy. to make a 90 deg corner ( most common angle done) each side is 1/2 the main number, or 45 deg. Same works if your angle that you want to do is 45 deg, say you want that 90 deg corner to have a small "flat" in it, just like the 2 shown in your bumper.. Now your main number is 45 deg, so 1/2 of 45 is 22 1/2.Since metal cutting saws don't typically come marked, like wood saws do,  a 45/90 square will set the saw for your major angles, or do layout with  a protractor. 30/60 triangles can also be of use occasionally. Now what can complicate things is what you have in your bumper. you have a compound angle because the piece not only angles, it also slants down. Wood workers have this issue a bunch when they try to cut crown molding. The "secret" is to set the material at the angle that you need it cut in the saw. Jigs make this easy so you maintain a constant angle and can clamp. Trick is to cut the pieces upside down. Top now faces the bottom of the saw, and bottom up when cutting. Now you just have to set the angles as mentioned above, 45 deg to get your 2 matching cuts for 90, 22.5 to get 2 matching cuts for 45 deg. The "up/down" part is dealt with by having the piece at an angle against the fence in the saw.Doing it by "hand" gets a bit more complicated. I'd need to do 3 D drawings to show how it's done, but it can be done by some simple math and connect the dots once you locate the distances apart the 2 pieces are. If you know how to do isometric drawings it's not that difficult. If I get a chance later to work out some drawings than make sense I'll post them up..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I prefer this type personally, but essentially the one you posted and these serve the same purpose, just different types of the same instrument:--Wintermute"No man's knowledge here can go beyond his experience." - John Lockewww.improvised-engineering.comManufacturer Agnostic:Blood----------Sweat---------Tears----|------------------|----------------|----Lincoln Red, Miller Blue, Esab Yellow
Reply:"Is it hard to use?"Do you know how to read a vernier scale? That would be the first "difficulty". It's not hard but I am often surprised by how many people do not know how.I bet you can look up instructions online.Don't talk about it, Just do it!
Reply:Originally Posted by DSWIf you know the angle total to lay out, it's easy. to make a 90 deg corner ( most common angle done) each side is 1/2 the main number, or 45 deg. Same works if your angle that you want to do is 45 deg, say you want that 90 deg corner to have a small "flat" in it, just like the 2 shown in your bumper.. Now your main number is 45 deg, so 1/2 of 45 is 22 1/2.Since metal cutting saws don't typically come marked, like wood saws do,  a 45/90 square will set the saw for your major angles, or do layout with  a protractor. 30/60 triangles can also be of use occasionally. Now what can complicate things is what you have in your bumper. you have a compound angle because the piece not only angles, it also slants down. Wood workers have this issue a bunch when they try to cut crown molding. The "secret" is to set the material at the angle that you need it cut in the saw. Jigs make this easy so you maintain a constant angle and can clamp. Trick is to cut the pieces upside down. Top now faces the bottom of the saw, and bottom up when cutting. Now you just have to set the angles as mentioned above, 45 deg to get your 2 matching cuts for 90, 22.5 to get 2 matching cuts for 45 deg. The "up/down" part is dealt with by having the piece at an angle against the fence in the saw.Doing it by "hand" gets a bit more complicated. I'd need to do 3 D drawings to show how it's done, but it can be done by some simple math and connect the dots once you locate the distances apart the 2 pieces are. If you know how to do isometric drawings it's not that difficult. If I get a chance later to work out some drawings than make sense I'll post them up.
Reply:Originally Posted by Brent878I am also intested, going to start a project like this soon and curious to any tips or scrects.  My plan is to do it out of cardboard and wood to hopefully get the angles right before I cut the metal.  How did you design ths one?
Reply:I don't know if this will help. The green line is say 2" ( the width of the material you are working with) and you want to do a 90 deg corner.  The height up from the top to the bottom determines how far "out" to the sides the bottom will sit ( blue lines) Figuring the cut angle is as simple as moving over the distance of the blue line and connecting the dots to the top inside corner if this makes sense.  The one view is at an angle from the side, the 2nd is the view straight down from the top. Attached ImagesLast edited by DSW; 03-03-2014 at 03:52 PM..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I do not know how to read a verneir scale.  I am looking it up now and its still a bit fuzzy, I think I would need to try it out in person.  Never had to get that accurate before.  I think I might have some calipers at home that may have it, i'll have to check and pratice.
Reply:Put your location in your profile.  There may be a member close enough to you that can show you how to do this.  It is much quicker and easier to teach someone in person.GravelThe difference between theory and practice is that in theory there is no difference.
Reply:Originally Posted by GravelPut your location in your profile.  There may be a member close enough to you that can show you how to do this.  It is much quicker and easier to teach someone in person.
Reply:Originally Posted by DSWIf you know the angle total to lay out, it's easy. to make a 90 deg corner ( most common angle done) each side is 1/2 the main number, or 45 deg. Same works if your angle that you want to do is 45 deg, say you want that 90 deg corner to have a small "flat" in it, just like the 2 shown in your bumper.. Now your main number is 45 deg, so 1/2 of 45 is 22 1/2.Since metal cutting saws don't typically come marked, like wood saws do,  a 45/90 square will set the saw for your major angles, or do layout with  a protractor. 30/60 triangles can also be of use occasionally. Now what can complicate things is what you have in your bumper. you have a compound angle because the piece not only angles, it also slants down. Wood workers have this issue a bunch when they try to cut crown molding. The "secret" is to set the material at the angle that you need it cut in the saw. Jigs make this easy so you maintain a constant angle and can clamp. Trick is to cut the pieces upside down. Top now faces the bottom of the saw, and bottom up when cutting. Now you just have to set the angles as mentioned above, 45 deg to get your 2 matching cuts for 90, 22.5 to get 2 matching cuts for 45 deg. The "up/down" part is dealt with by having the piece at an angle against the fence in the saw.Doing it by "hand" gets a bit more complicated. I'd need to do 3 D drawings to show how it's done, but it can be done by some simple math and connect the dots once you locate the distances apart the 2 pieces are. If you know how to do isometric drawings it's not that difficult. If I get a chance later to work out some drawings than make sense I'll post them up.
Reply:I just posted a reply to a similar problem. All you need to do is draw your shape, then with a compass and a straight edge, bisect the angle. To do this, just set up compass and draw an arc that intersects one leg of the angle, then the other. Next, open your compass and (pivoting from those two intersections), draw arcs that intersect each other. From that intersecting point to the original corner, draw a straight line. Voilà there is your bisected angle! Use an adjustable bevel square to set up your saw. No fancy math, or precision instrument reading necessary!Sent from my iPhone using Tapatalk
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Reply:Originally Posted by ironwrxI just posted a reply to a similar problem. All you need to do is draw your shape, then with a compass and a straight edge, bisect the angle. To do this, just set up compass and draw an arc that intersects one leg of the angle, then the other. Next, open your compass and (pivoting from those two intersections), draw arcs that intersect each other. From that intersecting point to the original corner, draw a straight line. Voilà there is your bisected angle! Use an adjustable bevel square to set up your saw. No fancy math, or precision instrument reading necessary!Sent from my iPhone using Tapatalk
Reply:Good question. I think that probably compounds your angles, so my guess would be that this would probably not work for this particular situation. Sorry. You'll probably have to use rocket science for this one. Lol, but keep this in mind for flat work. It does work well. Good luck.  Sent from my iPhone using Tapatalk
Reply:Originally Posted by ironwrxGood question. I think that probably compounds your angles, so my guess would be that this would probably not work for this particular situation. Sorry. You'll probably have to use rocket science for this one. Lol, but keep this in mind for flat work. It does work well. Good luck.  Sent from my iPhone using Tapatalk
Reply:You got that right, I'm 51, and still learning. Just remember if you use the compass, you can't get lost!  Ha ha. Sent from my iPhone using Tapatalk
Reply:I use sketch up to fully build my design off rough measurements before moving forwardThe program will let you get precise measurements and all you have to do is connect the lines and it will give you the angles.
Reply:Or do it the easy way.  Use cardboard to make a mockup once you've determined the top profile of the bumper.  Then use the templates to cut the steel.If you eyeball your angles where they please you(centering the angles/cuts top to bottom), they can be arbitrary angles as long as they're close.  And they'll look ok if you duplicate the same angles one both sides of the bumper."Any day above ground is a good day"http://www.farmersamm.com/
Reply:This is how I did it. (granted mine isn't actually built yet, just cut) Cardboard mockup. Which by the way works way better if you don't fully cut the cardboard in half. Slice one side, and hinge it on the uncut side so its not a mess of paper barely holding structure.and then draw it on computer so I know everything fits properly.As ridiculous as it sounds, I have been researching building plate bumpers for a while now before deciding to tackle it myself. I see a lot of bumpers just built in place and designed as you go which to me is a bit half-assed. (no offense). Me personally, if I am going to commit to an idea and a build, im gonna take the extra time to make sure it comes out the way it should the first time. Take time to make time. In the end, taking that extra hour to draw it on the computer or make it out of cardboard could save me hours of frustration.Attachment 655131Attachment 655141Last edited by BrooklynBravest; 03-14-2014 at 10:47 AM.
Reply:I did mine on the truck. I got frustrated trying to build it of the truck, I felt like I couldn't make it fit the with out building on it
Reply:I did use the card board to get the angles close