This is a script for creating a cutting pattern for joining two round tubes.
There is another version of this script that should scale the page size to the pattern size. It may not work for everyone, so use at your own risk. Here's the link:
http://metalgeek.com/static/cope_custom.pcgi
pattern height: 3.14"
common sizes
| Tube Gauge | Decimal | | | Pipe-nom. | Decimal | Wall (sch 40) |
|---|
| 10 | .134 | | | 1/2 | .840 | .109 |
| 11 | .120 | | | 3/4 | 1.050 | .113 |
| 12 | .109 | | | 1 | 1.315 | .133 |
| 13 | .095 | | | 1-1/4 | 1.660 | .140 |
| 14 | .083 | | | 1-1/2 | 1.900 | .145 |
| 16 | .065 | | | 2 | 2.375 | .154 |
| 18 | .049 | | | 2-1/2 | 2.85 | .203 |
| 20 | .035 | | | 3 | 3.500 | .216 |
A few notes
If you try to enter a tube size that's over 10 inches in diameter (or under .1), you'll end up back at 1 inch. The reason for this is that the overall calculation gets too big to handle here, and PHP runs out of memory. The other problem is that the best way to print the pattern is in PDF format, and I haven't found an easy way to make the page oversize or tiled. So the best solution for doing larger tube sizes is to scale everything down and then blow it back up with your printer. Let me know if you think you can solve this problem better.
This script makes use of cookies (if you have them enabled) to store your most recent entries. This should save you some annoyance if you're using metric or if you happen close the window and then realize you just want to change the angle a couple of degrees.
Description
This is a reconstruction and expansion of Eric Fahlgren's clever "miter" program written in 1994 to help in building bicycle frames.
The PDF version seems to scale best without regard for browser or OS weirdness. Make sure you have "none" selected under "page scaling" in the Acrobat print dialog or your pattern may come out just wrong enough that the problem won't be obvious until you try to wrap it around the tube.
The PDF is converted from a simple postscript file with ImageMagick. The scale seems to be pretty good either printed or imported into something like Adobe Illustrator.
If you have kudos, complaints, or pictures of things you've made with this that you'd like to share, just let me know. If I get enough interesting pictures, I'll put up gallery (with credits, if you'd like).
Some Explanation
In case it's not entirely obvious, the point of this thing is to create a cutting pattern for a tube or a pipe to accurately fit it at an angle to another tube or pipe so that you can weld or braze it. This is a whole lot easier than eyeballing the cut and scribing it by hand, and if you do it right, both the grinding and welding are pretty easy. This process is also frequently called "tube notching" or "pipe notching". Apparently, this script/form/PHP widget has become popular with a number of hot-rod, off-road, and vehicle modding
freaks engineers.
"Offset" is the distance between the two axes of the tubes. In other words, it moves one tube sideways in relation to the other tube. If you try to join two 1" diameter tubes and specify an offset of 1", then the coping pattern will be completely flat, because the tubes won't intersect. Although I thought that wouldn't be useful, Jurgen Schulz wrote to tell me that you could take advantage of that trick to miter a tube to a flat surface.
Specifying the tube's wall thickness makes the cut fit to the inside diameter of the tube, which makes it easier to fit, and makes a nice notch for welding. If you're trying to get a really snug fit, like for brazing a bicycle frame, you might want to try selecting a rather small number for the tube thickness. But if you get carried away with making it perfect, you'll spend a lot more time grinding it down.
Sometimes, I find I need to specify a wall thickness that's actually a tad smaller than it is in reality. I don't know if this is because of my sloppy grinder work, or my sloppy math. Some experimentation may be necessary to get it just right, depending on you own techniques.
For really big pipe, you might want to use a cutting torch, but most of the time I just use a chop saw to get it close and then an angle grinder to finish it up.
Can you give me a stand-alone version of this so I can run it on my laptop out in the shed where there aren't any internets?
No. I'm not really a programmer and writing this whole thing from the ground up is just too much for this busy old geezer to take on right now. Web scripting simple. Actual programming hard. Just thinking about it makes me want to take a nap. And another nap.
If you're a real geek, you could always just set up a web server with PHP and ImageMagick on your own computer and just run it yourself. But if you were a real geek, you'd already have wi-fi in your shed, so you wouldn't care.
Update on the stand-alone program thing:
Dan Hopper has written a little DOS program that's slightly similar to the coping calculator. You can check it out here.
Notes on the input fields
To keep the server healthy, I've set the following limits:
Tube diameter: .1" minimum, 10" maximum (2 / 200mm)
Wall thickness must be greater than zero
Minimum angle 10 degrees
Maximum angle 90 degrees
It usually works best to set the wall thickness a little smaller than actual, or the fit may be too loose. This depends on your grinding and welding style. If you want to cut the pattern at 0" thickness (the theoretical OD), just see this, and note the difference between .01" and .0001" on the image at the bottom of the post. Most of that would be thinner than aluminum foil. And that's still not 0".
You may also have to set the tube size a little fatter because tube is frequently oversized or irregular. If you're using heavy paper, this also adds a little to the size.
If you've been paying attention, this will sound repetitive, but before you complain to me about the size being wrong, make sure you have "none" selected under "page scaling" in the Acrobat print dialog.
Even more notes
Russell asked me to add some more notes for newbies:
Mark a reference line down the tube (both ends), thenuse the grinder to cut the pattern after tracing with a silver pencil. Thesilver pencil shows up really well on the black mill finish on 4130 tubing.I then grind until the pencil mark is just a hairline all the way around.
I like to use a silver Sharpie, because I'm old and can't see pencil lines without co*ke bottle glasses. If you're doing mass production, make the pattern a little oversize from card stock and mark the tube with white auto primer spray paint. It dries fast and resists heat.
My usual process is to rough-cut the pattern free-hand on a 14" abrasive saw, and then finish it up with a 4-1/2" flap disk. I've been buyiing those from Lehigh Valley Abrasives lately, because they're dirt cheap and I go through them like popcorn. And no, they aren't paying me.
Donations
If you feel so inclined, you can help me pay for the web hosting of this site right here.
FAQs
Joining the end of one piece of tubing to another is known as notching or coping (pronounced like "hope" with a c instead of an h) the tube. It's all based on angles that are determined by where you are placing the tube.
How much should coping stick out? ›
Your coping should stick out just enough that it makes tricks easier, but not so much that it impedes your flow. The best method we found to fasten the coping was to drill it into a parallel running 2x4 support directly behind it.
What is the diameter for coping? ›
The coping is typically a metal tube that is anywhere between 1-3 inches in diameter. This coping is used to grind and do tricks. Every sport uses a coping for their ramp- BMX, In-line skating, scooters and skateboards.
What is the formula for a tube? ›
Volume of a Tube
The volume of a cylinder is V=πR2h V = π R 2 h . This volume of the cylinder will be the same as the volume of the tube if there is no hollow portion.
Is tube measured by OD or ID? ›
Tubing is measured by the OUTSIDE DIAMETER (O.D.), specified in inches (e.g., 1.250) or fraction of an inch (eg. 1-1/4″). Pipe is usually measured by NOMINAL PIPE SIZE (NPS).
What does a tube bender do? ›
While there are a number of different types of tube bending machines, including press benders, rotary draw benders and roll benders, the basic purpose of these machines is to create a curved tube by putting pressure on a metal pipe so that it bends at a precise angle.
How do you notch PVC pipe? ›
Just place the mark you want to the pipe cut against the blade of the cutter, then squeeze until it comes into contact with the pipe wall. Release the mechanism, then squeeze again, and repeat until the blade is all the way through the pipe.
What tool should you use to notch a tube? ›
One of the many tools you're bound to find in an auto shop is a tube notcher. Mechanics use this awesome tool to create “fishmouth” notches in metal tubes.
How far should coping overhang? ›
Step 4: Coping should overhang approximately 2″ (50mm) and slope at a 2% grade away from the pool. Use a string line to maintain straightness and a torpedo level to maintain the slope of each unit.
Does pool coping have to overhang? ›
The standard overhang for bullnose coping is 1.5 inches but it comes down to preference. The maximum bullnose overhang is roughly 3 inches. The popular coping design comes in several variations, including: Full bull-nose: This style has a full curve at the edge of the coping.
In addition to repairing coping if it cracks or becomes damaged, another safety consideration is in choosing the right color. In the Valley, lighter colors are essential because dark colors absorb the heat from the sun and can get blisteringly hot.
What is coping scale? ›
The Coping Scale is a self-report for children, modified based on the Self-Report Coping Scale (SRCS; Causey and Dubow 1992; Kochendefer-Ladd and Skinner 2002). Children are asked what they would do if something bad happens.
How thick should skate coping be? ›
About 3/8″ is fine each way, preferably no more than this and no less than 1/4″. – it is the correct size. We have seen ramps with no coping when there should be a coping, and we've seen ramps with coping too small, some too large. – people do not wax it.
How do you make a coping kit? ›
Be sure to include headphones, chimes, or a rainstick. Touch: Choose items you can hold or rub in your hands or even on your body that are soothing or calming to you. A smooth rock, silly putty, a stress ball, a massage roller, textured cloth, a fluffy stuffed animal, or a weighted lap blanket.
How do you calculate flow rate in a tube? ›
The flow rate is given by Q=A¯v or ¯v=Qπr2 for a cylindrical vessel.
How do you calculate tube thickness? ›
Answer: Having the inside dimensions (ID) and the outside dimensions (OD) will allow you to figure out the wall thickness on tubing. You would need to subtract the ID from the OD and then divide by two. This number is the wall thickness.
Is 2 inch pipe ID or OD? ›
Select Schedule:
| Pipe Size | OD | ID |
|---|
| 2" | 2.375 | 1.503 |
| 2 1/2" | 2.875 | 2.635 |
| 2.469 |
| 2.323 |
96 more rowsThe nominal dimension for pipe is the ID. So, 1½ inch pipe is NOT 1½ inch outside diameter, but instead is nominally, (approximately) 1½ inch inside diameter.
Is OD bigger than ID? ›
The outside of the pipe is always larger than the inside. The difference between the inside diameter (ID) and the outside diameter (OD) is due to the thickness of the wall. Wall thickness also determines the strength of the pipe.
What is the the formula for volume? ›
Whereas the basic formula for the area of a rectangular shape is length × width, the basic formula for volume is length × width × height. How you refer to the different dimensions does not change the calculation: you may, for example, use 'depth' instead of 'height'.
In order to determine the Flow Rate represented as Q, we must define both the volume V and the point in time it is flowing past represented by t, or Q = V/t. Additionally Flow rate and velocity are related by the equation Q = Av where A is the cross-sectional area of flow and v is its average velocity.
How do you calculate drainage volume? ›
To calculate the volume of water that needs to be stored, multiply the amount of runoff from each drainage zone by 15. The runoff for each zone was in gallons per minute. Multiplying by 15 minutes leaves you with the amount of gallons to be stored.
What angle do you cut a pipe for a saddle? ›
35 degrees work great for pipe of the same diameter, but saddles are often done on various size pipe. If the pipe being cut fits over the pipe being saddled, then set the saw to 45 degrees.
How do you measure a pipe saddle? ›
Measure the Outside Diameter (OD) of your pipe or pipe fitting:
- Wrap a string around the pipe.
- Mark the point where the string touches together.
- Use a ruler or measuring tape to find the length between the tip of the string and the mark you made (circumference)
- Divide the circumference by 3.14159.
And, it's a common myth that a solid rod bends easier than a hollow tube of the same material. Fact is, given the same material, a solid rod is stronger in all respects than a hollow tube of the same material.
How tight can you bend tube? ›
Minimum roll bending radius is 7 x D
It is technically feasible to be tighter than 7 x D but it depends a lot on wall thickness and material properties, so for safety stick to this guideline.
What does the R mean on a tubing bender? ›
The “L” is the 90° bend point and “R” is the 60°. However, if you needed to make a reversed 90° bend, you would line your 90° bend mark up with the “R”. When bending tubing, the “R” is for reverse bend.
Does PVC need to be cut perfectly straight? ›
Place the pipe inside the jaws of the cutter, making sure that the blade lines up with the mark. With scissor-style cutters, apply pressure to the handles and slowly rotate the cutter around the pipe. Making sure the cut is straight, continue to rotate until you cut through the pipe.
What is notching adjustment? ›
Notching is when a credit rating agency bumps up or down the credit rating on an issuer's specific debts or obligations. Because certain types of debt—for instance, subordinated debts—are riskier than senior debts, the rating on junior debts can be notched lower.
How is notching done? ›
Notching is a metal-cutting process used on sheet-metal or thin bar-stock, sometimes on angle sections or tube. A shearing or punching process is used in a press, so as to cut vertically down and perpendicular to the surface, working from the edge of a work-piece.
Sawing is one of the most versatile and widely adapted methods for cutting tubing.
How do you calculate tubing bends? ›
Calculating the tubing in a bend is very simple. We already did the calculations for you. Just multiply the degrees you're bending by the numbers below and you will get the length of tube in the bend. So if you're bending 90 degrees on a 6″ CLR die, your tubing in the bend is 90 * .
Are notches necessary? ›
Correct use of pattern notches are essential to ensure that the tension along a seam remains even and that fabric is not stretched as it is sewn.
What is a notch How should notches be cut? ›
Notches are clips or wedges cut into the seam allowance in order to facilitate matching and sewing the corresponding seams during garment construction. In other words, you can figure out which fabric pieces should be pieced together to form the seam by matching the corresponding notches to one other.
What are the two methods of cutting a tube? ›
Shearing: Shearing or shear cutting is the process of cutting a tube or pipe under the sheer force of two plates and ID punches. The tube is sheared between the ID punches and plates to cut it. Lathe Cutting: Cutting is one of the effective operations performed over a lathe machine.
Which is the correct way to construct a 45 angle? ›
45 Degree Angle
- Construct a perpendicular line.
- Place compass on intersection point.
- Adjust compass width to reach start point.
- Draw an arc that intersects perpendicular line.
- Place ruler on start point and where arc intersects perpendicular line.
- Draw 45 Degree Line.
Measure the Outside Diameter (OD) of your pipe or pipe fitting:
- Wrap a string around the pipe.
- Mark the point where the string touches together.
- Use a ruler or measuring tape to find the length between the tip of the string and the mark you made (circumference)
- Divide the circumference by 3.14159.
How to calculate cross-sectional area of a pipe? To calculate cross-section of a pipe: Subtract the squares of inner diameter from the outer diameter. Multiply the number with π.
Do you measure the inside or outside of a pipe? ›
When it comes to measurement of pipe, it is measure by the inside diameter, often called the nominal diameter. Nominal Pipe Size (NPS) is a North American set of standard sizes for pipe.
What is the rule of thumb for pipe sizing? ›
A rule of thumb that incorporates pipe size is to choose liquid lines to handle a velocity of 1.5 +d/10 where “d” is the pipe diameter, inches. This gives 1.6 m/s for 1-inch and 2.5 m/s for 10-inch piping, and about 20 kPa/100 m pressure drop.
volume = π (pi) × radius squared × length. volume = 3.14159 × (. 5 x . 5) × 600.
Which is bigger 3 4 or 22mm pipe? ›
3/4 pipe is significantly smaller than 22mm.
Is pipe size measured by ID or OD? ›
The nominal dimension for pipe is the ID. So, 1½ inch pipe is NOT 1½ inch outside diameter, but instead is nominally, (approximately) 1½ inch inside diameter.
Is cross-section same as diameter? ›
Well, the diameter of this circle is the diameter of the conductor, while the area of the circle is what is known as the cross-section of the conductor. The cross-section is therefore the area, expressed in square millimetres, formed by the copper wires passing through the insulating sheath.
What is the cross-sectional area calculator? ›
The cross-sectional area is the area of a two-dimensional shape that is obtained when a three-dimensional object - such as a cylinder - is sliced perpendicular to some specified axis at a point.
Which method of measuring pipe is the most accurate? ›
The string method (which measures the pipe's circumference) is probably the best way to determine your pipe diameter size. The circumference is the distance it takes to go around the pipe once.
Does pipe size affect pressure? ›
Larger pipes increase the water flow through the line, but if the water isn't up to that necessary flow, it won't increase your water pressure. Municipal water systems have impressive pressure, but that doesn't mean a larger line can help. Bigger lines do not always help things get faster o stronger.
Does pipe size affect flow rate? ›
At any given flow rate, flow velocity is inversely proportional to the t cross sectional area of the pipe. Smaller pipes will lead to higher flow speeds; larger pipes, will lead to slower flow speeds.
What are the 3 factors to be considered in determining the size of the pipes required for sizing supply lines? ›
Three Steps to Sizing Plumbing Piping Systems
- Add up the total number of water supply fixture units (wsfu) required in the facility.
- Estimate demand using the table from the IPC that correlates wsfu to expected demand.
- Size the pipe using demand vs. friction loss curves found in the IPC charts.
