We're currently in the process of loading all of our steel tube stock into our tubing store. To date we have rectangular and some square tubing loaded, round tubes will follow shortly. We thought this would be a good time to address one of the most common requests that we get from our customers, tubing that will slide together or telescope. While it's certainly possible to purchase tubes that will slide together with a nice snug fit (similar to the picture at left) it's not as simple as it seems.
A common misconception is that a tube with an outside measurement of x will slide into a larger tube that has the same x measurment on the inside. It won't. As an example, a round tube that has an outside diameter (O.D.) of 1-1/2" and a 1/4" wall thickness will have an inside diameter (I.D.) of 1". Seems logical then that a piece with a 1" O.D. will slide right into it with a nice snug fit, right? It won't. You'll simply be butting 1" up against 1" and the two pieces will not telescope. In order for these two pieces to slide together you'll have to remove some stock from your 1" O.D. piece or hone out the inside of your 1" I.D. piece.
Round tubing has a multitude of walls and O.D.'s available. Typically a good pair can be found that requires little or no work to get the desired fit. Square and rectangular tubes are completely different stories though. The bulk of them have raised seams on the inside and they all have inside and outside corner radii that differ with each size.
If you're in the market for telescopic tubing we'd strongly suggest that you call us first to discuss your project. We can assist you with size selections from our inventory and if a case comes up where even we're unsure of a good fit we'll physically check it in our warehouse and promptly report back to you.