Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / Welding Fundamentals / Determine the radius: here's a riddle for you to figure out
- - By aevald (*****) Date 10-26-2007 21:29 Edited 10-26-2007 21:33
Hello all, I have a formula that I cover in a fabrication class that I teach for determining the radius and thus the diameter also. If you don't have the ability to measure completely around something or if it isn't a complete circular piece it can be challenging to figure out the radius or diameter of something. See if you can understand how this works. Regards, Allan
Attachment: radiuspaper.bmp (681k)
Parent - - By monsoon12 (**) Date 10-27-2007 00:53
Hey aevald looks like some geometry an trig going on there.Been awhile, alittle rusty .Though theses are subjects a welder /fitter needs to know.Thanks so much for sharing.
Parent - - By aevald (*****) Date 10-27-2007 03:38
Hello monsoon12, I should have prefaced this a bit better so that it makes sense. The formulas and process that are discussed and figured out on the page that I included as an attachment are an example of a way to determine radius and diameter when you can't readily do so in any conventional manners, circumference divided by PIE, measuring straight across the end of something round and recording the greatest distance.
     The line that you see going straight across the radius in the picture can generally be substituted by using a 12" rule, 3 foot straight edge, or some other sort of measuring stick that is straight. 1/2 of the length of this device is then used for the Run portion of the triangle, measuring from the 1/2 way point up to the top of the radius becomes the Rise portion of the triangle. Once those two dimensions have been taken you can plug them into the formulas as I did in the example and figure out any radius.
     The practical application of this formula for me, might be as follows: I was on a field job once and we were told that we needed to take measurements from an infeed chute to a drum de-barker in a sawmill. This particular chute was about a 1/3 round and roughly 9 feet long. They wanted the sleeve to be made from 3/4" wear plate. We had a choice, we could make a plywood template of the radius of this chute and send it into town with someone so that they could take it to the shop that would be making this sleeve, or we could determine the radius, give them the running length of the radius and the length of the part and call them with the information and then have them cut and form it and ship it up to us.
     Using the formula and process on the attachment in my first post we were able to determine the radius very exactly and supply the shop in town with this information and they were able to make it and ship it to us without a bunch of extra road trips. It also fit in very well and made the installation and weld out go without a bunch of hitches and unnecessary handling and jacking, wedging and dogging. Hope this may have explained it a bit better. Best regards, aevald
Parent - - By DaveBoyer (*****) Date 10-27-2007 04:35
This method works if the part is in fact a section of a circle, something You need to verify FIRST.
Parent - - By Tommyjoking (****) Date 10-27-2007 08:18 Edited 10-27-2007 08:24
Allan your making my big fat head hurt!!!!   LOL! Thats why I quit the electrical engineering thing  math math math.....uggh.     Actually a neat post....you know those little fitters bibles are fantastic resources full of this kind of info ..everyone should have one.  BTW can anyone recommend a particular one that is real good?  I am in need of one myself.    (not just pipe copes but the whole shebang ...cones, compound radius calc, sheetmetal work etc.)  THX in advance!
Parent - By aevald (*****) Date 10-27-2007 16:42
Hello Tommy, I do have a number of books that I can recommend for you to look at, or for. They are at work right now and I am home. When I get back into the office I'll see if I can round them up. As far as the math thing goes, I have boiled the majority of things that I use relative to fabrication and fitting to about 7 or 8 different formulas. Back at you later. Best regards, Allan
Parent - - By aevald (*****) Date 10-29-2007 14:48
Hello Tommyjoking, I did manage to find a few of the books that have some of the items that you mentioned about layouts, copes, etc. The first one here is: Triangulation Short-Cut Layouts, fourth edition, Kaberlein sheet metal series, another one: The Pipe Fitter's and Pipe Welder's Handbook, Revised Edition, Thomas W. Frankland, another: Second Edition, Electricians Guide To Conduit Bending, by Richard A. Cox, this one's an oldie, The New Metal Worker Pattern Book, by Geo. W. Kittredge, circa 1913, one more, A simple guide to BLUEPRING READING, by William N. Wright, this one's been around a while too, 1942. I have a few more too Tommy, but I'll have to do a little more digging to locate them. Most of these books have a number of different things that answer some of your questions, sorry I don't believe any one of them is all inclusive. Best regards, Allan
Parent - By RGL (*) Date 11-27-2007 18:03 Edited 11-27-2007 21:18
   There is a Hand Held Calculator on the website link below that can layout just about anything, and very user friendly, including Arc's and Large Radius's. See the two attached files from the Manual that comes with these Calculator Programs. You just input the dimensions it prompts you for, and it will give you all the layout dimension's you need for the layout.  You don't need to know the math and its Dead Accurate.   You can use the Layout Manual that comes with it like a computer monitor for visual instruction and direction.   It will also layout Square to Rounds, Round Elbows, Intersecting TEE's at any angle including the HOLE layout, Conveyor Screws, Stair Cases, handrails and much more. It always reads dimensions in DECIMAL form 1st,  then in FRACTIONAL form 2nd,  to the closest 1/32",+/- 1/64".  This is for the person that doesn't know his/her Decimal readouts. It also has Utility programs for FINDING the RADIUS of an Arc,  the DEGREE of an Arc,  the CORD across an Arc,  the DEPTH of Cord and the LENGTH of Arc,  using the same excellent formula's that "aevald" is showing above. I have to say, by everything he has posted,the man "aevald" knows his TRIG well. It also has Drill & Tap sizes, Metric Conversions, Pulley sizes, including RPM and Belt lengths and more.  This is a hell of a tool for people that don't have any layout experience or know the math.  The site shows all the pages in the manual, just click on each page.  Be sure to read all the "NOTES" in the pages, it helps things make sense.  This Calculator is a Real Tool, its not a gimmick or a toy.  Its worth a look at.
  The very 1st 2 programs that I wrote were for this Large Radius job shown below. I wrote them back in the early 80's for the Apple II Plus computer that are written in this Calculator today. (ARC'S & CORDS and TAPER or CONE LAYOUT,Multi Piece). After taking Cord & Depth of Cord Dimensions, top and bottom, shooting the heights with a builders level, knowing the width of the copper sheets to be used,(Allowing for Seam's) and measuring around the parimeter at the bottom, (All Field Dimensions), I quickly calculated the number of panels for the cone layouts.  It took about 2 1/2 hrs. to completly Layout these copper roof's with Number of Piece's, full multiple piece total lengths, (5 piece's per length of panel) and O.D. width's of all panels from the bottom of the panels to the top of the panels, in 5 sections using 10 ft. stock sheet lengths and ready for fabrication.

http://www.sheetmetallayoutcalculator.com
Attachment: ARCSCORDS90dpi.jpg (91k)
Attachment: x11RADIUSLAYOUT90dpi.jpg (178k)
Parent - - By aevald (*****) Date 10-27-2007 13:10
Yes Dave, you are right about that. Regards, Allan
Parent - - By DaveBoyer (*****) Date 10-28-2007 03:38
An easy way to verify that the shape is part of a circle is to clamp 3 strips of metal together so that a corner of each rests on the surface of the curve. They should only spread enough to include 1/4 -1/6 of the surface. If this "fits" meaning all 3 touch as this tool is moved inside the curved surface it is semicurcular, if all 3 don't touch the surface is either irregular, or a different geometric shape.
Parent - By vagabond (***) Date 11-22-2007 16:04 Edited 12-07-2007 19:08
CHICO's pipefitting cards are very handy.  Necessary formulas on plastic cards.  Pricey but durable.  I love these things, but my Frankland books and ol' Blue are sufferin from seperation anxiety
Up Topic Welding Industry / Welding Fundamentals / Determine the radius: here's a riddle for you to figure out

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill