by James Morikawa
I always check the internal butting of the tubes. I do a check with the tubes in hand, to ascertain that they coincide with manufacturer's specifications.
This is the simple tool that I use.
It's a Machinist's Internal Diameter "Snap-guage", which has a wooden popcicle stick taped to one end.
Above is an example of it's use.
I set the gauge to the inside diameter near the end of the tube. This is where the tube wall is the thickest, and inside diameter the smallest. I then slide the gauge down the tube to where I notice an increase in diameter. At this point, I take note of the depth the gauge has been inserted into the tube, and with this depth, make a reference-mark on the tube. See the picture below.
Above you see the Top-Tube, and Down-Tube "reference-marked" where the thicker butt sections begins. These are also reference points I use during the tube mitering process. I don't want to be mitering the tube pass these marks.
This is rare, but I have come across tubes that didn't match up to their printed tube specifications. The tubes were not the correct ones. I could have missed this if I hadn't done the check. I rather be safe, so I always check.
Also, good practice to weigh the tube to make sure the actual tube weight is near that of it's weight specification. I have come across tubes that were too far off in weight, thus prompting me to investigate. You want to make sure you have the correct tube.
That's it for this page. Have a good day.