How to straighten a copper tube
Disclaimer: This review is not sponsored or paid by the supplier or anyone else. The product is payed by myself and I wanted to share my personal experience with you.
I’m not really a fan of specialized tools that can only be used for one single purpose and solves one specific problem. Neither in the household nor in my workshop. Nevertheless I found myself in need of buying a tool for solving a very specific problem. For different future ideas and projects like my Giant Vacuum Tube Model and a LED chandelier. I have been looking at using 4 mm copper tubing. The only problem is that it’s almost only sold in rolls that need to be straightened before it can be used – Unless you want to buy overpriced pieces of 1 m sections. First I didn’t know the name of a tool for solving this task, but found out it is called a handheld tube straightening tool or tube straightener. By searching around for ways to straighten copper tubes I came across many not very useful tips and tools. One YouTube video suggested to fix the tube in a clamp and then use a hammer to stretch it straight by hammering.
The first dedicated tool I found was a pair of pliers that just clamped around a 5-10 cm piece of the tube and then had to be repeated for the total length of the tube. Unfortunately the end result was not looking very convincing and my guess is that it would be a very time consuming job. Another way to straighten a tube, either large or small diameter is to force it through several ball bearings with a fitting for the specific tube diameter. This principle is often used when the tube is fed directly into a tube cutting or bending machine often with a dual tube straightening mechanism, one in the horizontal axis and one turned 90 degrees to the vertical axis. Another more compact version of this mechanism is to mount the horizontal and vertical parts together forming a cross like structure around the tube.
The only tool for the Job
Only one product repeated to show up through my searching; the Tube Straightening Tool from Kwix UK. After not being able to find a Danish distributor and with the, in my opinion, relatively high price I thought it would be rather simple just to 3d print the four pieces that holds the ball bearings together with the screws. First I tried to build a simple mock up with 6 cheap ball bearings mounted on a plate, but it couldn’t take the force from the straightening process and after a short testing the ball bearings all broke apart. After my first very bad prototype I quickly abandoned the idea of doing it myself and threw my money after the real product instead of wasting my time and money on the design process and materials. My hypnosis was that if a company can exist by producing one single product its better be good. And hopefully the price would reflect the quality of the product. Sometimes you need to focus on what you want to use your energy on, for me it wasn’t to design the deep plate over again.
The strange thing was that I wasn’t able to find any similar products for straightening a copper tube in my regular goto hardware stores. Not even though some of them actually sold copper tubes rolled on a spool.
Another challenge is to cut the copper tube in the right length or bend it at a specific angle, but this is not a problem since a tube cutter or tube bender are tools that can easily be found around in hardware stores.
A short introduction video from Kwix UK
Now lets get to the actual review of this product. My experience with this product is that it does a good job on 4 mm copper tubes. I haven’t tried with other materials, and only used the 4 mm version. The end result varies depending on if the tube comes fresh from the spool or if it has been slightly bend by hand in different directions. Then it is harder to get a good end result with a complete straight tube without small curves. But in my opinion this product does a pretty descent job. And it definitely feels sturdy and strong enough to withstand the force of the straightening process. THe hardest part is to get started on the tube, it helps to hand straight the first 10 cm. Then it is easier to get in inside between the wheels.
My only regret about the product is that I don’t feel like working with tubes in other diameters than 4 mm since I don’t want to invest in multiple tools to be able to handle different tube diameters. But for the professional user I definitely think it is worth it’s price even if you have to buy multiple sizes. I look forward to be using my tube straightener more for future projects.