Bending tubes without a tube bender

Heatpipes are rarely straight, that's why I had to find a way to bend my brass tubes. Bending a tube is not hard, you just put it over your knee and voila. Of course that would also put a huge kink in the tube and it could no longer be used for a heatpipe. The corners in a heatpipe need a nice curve because when the working fluid vaporizes it has to travel along the tube with minimal restriction, kinks and sharp corners are not good. To make nice bends in tube you need a tube bender. I did not have a tube bender and they're not available locally, buying one online would take ages to ship, especially considering it's xmas season. My only option was to DIY a tube bender, which is exactly what I did. I started out by going to my local hardware store and buying myself a pulley block and steel thimbles.


My plan was to use these as my dies to bend my tube around. My first try was with the steel thimble since it was easy to clamp the tube to it. In order to not waste any tube I tried bending the heatpipe that I had previously made. As soon as I started rolling the tube onto the tackle it immediately buckled. At first I thought I didn't bend it right so I tried again from the other end.....and it buckled again. I then noticed that the thimble didn't have enough support on the sides of the tube, which would cause the tube to kink.

The pulley should have a much better chance at keeping the tube from kinking since it fits around much better. The only problem is that the pulley is made of plastic and wouldn't hold the tube together too well. Fortunately the pulley is in a steel block and with a few scraps to fill the gap between the plastic pulley and the block I was ready to bend the tube.

I took a fresh bit of tube and started experimenting. First bend went better than with the steel thimble but still kinked. So I tried again with a little more care - same result. The brilliant idea of annealing the tube then came to mind. As expected after I annealed the tube with my butane torch it got much softer and easier to bend. Consequently the next bend turned out much better.
I then tried to anneal the tube better and bend it with more care. The bend turned out great with only the slightest evidence of a kink starting to form.

Seems like I can make a bend of about 3cm diameter with reasonable confidence. I then tried bending the tube to a much tighter radius but it quickly turned into a mess and you don't need to see it.
My next step was to improve the spacers I used in my tube bender because the ones I had in were messy and stuck out too much (My phone refused to save the pic of that for some reason).
A new piece of brass tube was then cut, well annealed and then bent into a 90.

The bend turned out well and compared to the heatpipe from an old Acer laptop looks to be around (cheeky pun) the same radius. The tube will be used in one of my upcoming projects. I say my tube bender turned out well, some improvements could be made but for now I think this is as good as it gets.
That's all for now, thanks for reading.

Komentarai

Rašyti komentarą

Populiarūs šio tinklaraščio įrašai

Playing with junk: the SN29764 (LM1017) 4-bit binary 7-segment display driver.

Vaizdas
    While digging through my parts bins looking for my spare arduino nano I came across a boart that I was keeping solely for the 7-segment display that was attached to it. I noticed that there also was an IC marked SN29764 on the board and got curious. After some googling I came up with a LM1017 datasheet, which states that it's an equivalent to the SN29764.      Basically what this IC does is it takes a 4-bit binary number through pins 2, 3, 4 and 5, and displays that number on a 7-segment display. Since this IC was made to display channels on a TV it doesn't display the number 0 but it displays numbers from 1 to 16. Pulling pin 1 down sets the display to full brightness.     I find it quite interesting that there would be a dedicated IC for this application but the world proves to be quite large and technology has sure advanced since the old days. There isn't a date code I can read on the IC but it might very well be older than me even, well I'm not even that old so
Skaityti daugiau

Infrared RGB LED controller using Digispark (Attiny85).

Vaizdas
    While building a PC I thought I'd toss in some RGB to see how it looks. Problem is I had lost the receiver. Bummer! But I still had the remote, so I decided to make my own RGB controller. For this project I chose to use the Digispark, which is like an arduino but is based on the Attiny85. A regular arduino like the arduino nano, or even any other microcontroller like the STM32 "blue pill" can be used for this project. In this case I wanted a small microcontroller, something like an atmega328p would have been a bit of an overkill.     Before I could make my microcontroller do anything I had to find out what my remote was transmitting. To do this I used my OWON VDS1022 USB oscilloscope, with which I saved the samples of the waveform in a .txt file. The bitrate of the signal transmitted by the remote is quite low so something like a DIY audiojack oscilloscope (look it up) would work also. The .txt file then was passed through a matlab script I quickly put togeth
Skaityti daugiau

Modding a laptop power brick into a lithium pack charger and some Manhattan style prototyping.

Vaizdas
      I've built a few 4S lithium battery packs but I didn't have a charger. So I decided to make one by modifying a switch-mode power supply. The power supply I used had a special plug on it with three pins. One of them being a sense pin to change the voltage. On this plug an adapter would connect, which would have a resistor in it that would change the voltage on the output. This power supply is nothing special, though. All this wire does is go straight to the REF pin on the TL431 reference IC inside. How do I know that? Because I accidentally blew the TL431 and had to pull the power supply apart to replace it. If you're willing to pull apart a laptop power supply you can add this wire to the TL431 reference and you'll have basically the same thing I have.     Opening them can be a pain. Mike from mikeselectricstuff shared in one of his youtube videos that whacking the weld/glue seam on the power supply will crack the joint and the power supply will come apart. But I&
Skaityti daugiau