Tube Coping

Make the cut of every tube end of a frame: a wrap-around template you print at true size and wrap round the tube, and a cut sheet with the length, angle and cope of each tube. It is for round, square and rectangular tubes that meet at an angle, such as a tube clamp setup or a weld table frame.

Step by Step

1. Open Cut List and press Tube coping.... The window opens.
2. To cope the tubes of the open part, press Use the tubes of this part. Tubes made with Sweep or Structural Member along straight lines are used; bars, angles and channels are named as left out.
3. To cope two tubes that are not modeled, set the tube to cope and the tube it meets (shape, outside size, wall), the angle between them (90 is a square T) and press Work out the cope.
4. Read the cut sheet below the buttons: the stock length to cut first (square, the longest side), the finished longest and shortest side, and for each end whether it is square, a mitre (degrees off square) or a cope (how deep, and onto which tube).
5. Pick a template to look at. Press Print this template or Download files (zip). Print the SVG pages at 100% (Actual size) and check the ruler bar on the page: it must measure 4 inches or 100 millimetres.
6. Cut the stock square to the length on the sheet. Wrap the template round the tube with its straight edge on the squared end, the red START LINE on the tube's start line, turning counterclockwise as you look at the end of the tube. Mark the curve and cut to it.

What You Get

• A template for every coped or mitred end, as SVG pages at true size. A template wider or deeper than a page is cut into overlapping pages to tape together.
• The unrolled curve of each end as a DXF in millimetres, to cut on a laser or plasma table.
• The cut sheet as text, CSV and a printable page.

How The Cope Is Worked Out

The end of a tube is where a straight line along its axis, from each point of its outside, first meets the outside of the tube it meets. The tube it meets is treated as running right through the joint. Tubes of equal size that meet end to end are mitred. When the two sizes differ, the smaller tube is coped onto the larger. The answer is the shape of the two outsides: a gap for fit-up, a weld bevel or a different method are the shop's own decision and are not added.

With AI

An AI connection can do the same: work out the tubes from a list or from the open part (fab.tube_cope), one joint from sizes and an angle (fab.tube_cope_joint), and get the template pages, DXF and cut sheet (fab.tube_cope_export).

Common Problems

• The template prints too small or too large. Print at 100% (Actual size), not Fit to page. The ruler bar tells you.
• A warning says part of the tube never meets the other. The coped tube is wider than the one it meets, or the centre lines are offset so far that part of it misses. That part stays at the joint plane.
• A tube is not listed. Only round, square and rectangular tubes are coped. The sheet says what was left out and why.