Hi David, thanks because I was beginning to question myself. I’ve devised a similar method but because I’m no expert its always useful to get an experts opinion on it incase there is a simple trick to a solution. It looks like there is no short cut here to what should be an easy problem. I think I was hoping for a surface solution along the lines of flowing along the surface from one end to the other.
Here is where I’m up to on the cut detail for the laser. Because most lasers cut normal to the tube, the wall thickness has to be taken in to consideration to prevent construction clearance problems later. What I did here was was create the intersections for the tube id and od then pulled the id curve to the od surface and also pulled the od curve to the id surface then trimmed the bits I didn’tLaser tube normalized.3dm (225.0 KB) want. Any thoughts on this?
Hi
Did you find a solution to make your metal tubes straight ?
I read this discussion yesterday
I did some tests and
Experiments in rhino to understand your problem
… I will share a video for the demonstration of the steps
… you would tell me if the solution is good or not.
since I am not sure to understand with certainty your probem
Hi, I dont have a quick solution and would be interested to see your video
Thanks
I aligned the construction plan (Cplanes) on the first end of the tube to be able to calculate the angles.
then I started to align the other end of the tube hierarchically,
by just calculating the negative value of the rotation angle.
using the gamball I carried out the operations.
… you have to work each pipe in a separate file
(it was a bit quick in the video,
I could remake another video with the detailed steps in the english version if the solution is good.
I recorded another video which shows the steps a little more clearly.
… the base length of the tube is 1589.628
I got 1649.791 length after straightening the angles.
it’s up to you to see which is the right one to carry out your bending operations on the tube
see below the working file
Laser tube sample 3 FARES.3dm (291.9 KB)
Thanks for the video Fares. Pascal Golay cracked it with a simple script with high accuracy.
i have the same problem, unbend a bent tube for laser cutting.
the easier way i can find in rhino is to normalize the end first and flatten the straight on each end. you do not have to measure the rotate and bend angle manually since you are in rhino. the pipe has a uniform seam. you just flatten the 2 ends from the same seam and align them up when flattened. they are garranteed aligned. all you have to do is to get the total length right.
The problem is if there are multiple bends in different planes but there is now answer and an improvement is being worked on.
multi bend pipe is the same as the seam runs the full length of the pipe, all you need is the two ends. it does not matter how many bends you have or how the bend rotates.
The question is how to orient the cuts at the ends so that when it is bent up, it it lines up to the intersecting tube.
-Pascal
I took a short video showing how it works, please note that I did not normalize the ends for laser cutting in the video, the most important thing to know is that there is a seam running through the full length of the tube or pipe, and the unroll command flattens the 2 straights from the seam, they will align up on the same plane, and you do not have to do all the measurement in the 3d space.
I am new to rhino, all my 3d drawing is done in Solidworks, the cylinder will be split into 2 half so I have to rebuild the cylinder on the 2 ends, then trim, then unroll. maybe there is a way to avoid the split and rebuild.
the flattened pattern is oriented at the seam, the tube I work on in the video has 2 bends, a 2 bends tube is the same with a 10 bends tube when you understand how it works, you do not have to bother with the rotation.
I have both tube laser cutter and CNC bender. I should say unbending the tube is just one of thw steps you should go before the tube is ready for welding. the bend location, bending extention and the orientation of the cope relative to the bend.
It’s a good effort but Pascal has a better solution which delivers you a centre line wire representation of the unbent tube complete with correctly orientation of end cope curves. He understands what is needed for unbending tubes for laser and hopefully is working on developing it into a plug-in. Bobi at Rhino Bulgaria has huge experience with modelling race car chassis tubes for laser cutting and I think with his input of some tips of what options might be of benefit from a practical point of view to produce cut tubes, a perfect plugin could be developed. Bobies excellent work on the Bentley LM race car can be found on the Gallery page of the Rhino forum.
Bendtech software has the ability to unbend tubes and normalise the end copes at the click of a button. All that is required is select the tube end to be cut then select the cutting tube and you are done. Visually you can see that the end of the tube has been normalised. I have this software but it doesn’t allow you to export the cutting files unless you buy one of their tube cutting machines.
This is an industry wide problem that there is no real solution. Most people will model the tube in Solid Works and it would be a useful tool to add to Rhino.
Please find link to you tube video of Bobi working on race car tubes to be laser cut.
I can see the chassis, it looks very impressive
but I have to say there is no need to normalize the end of straight tube. In my case the tube cutting machine comes with a cam software which can normalize the tube ends with a click. Say there are 50 straight tubes of various size, the cam software can take the whole assembly or multibody part in one import and process them all in a few seconds. The problem is the nesting file works on the tube cutting machine only and can not be exported.
If you are in race car industry and use Solidworks and have the need to bend and laser cut tube, you may want to take a look at tubeworks plugin for solidworks, which tackles all the problem we discuss here and gives you a neat straight solid tube and bending data.
I will go through the whole thread and see if there is anything I am missing.
by the way there is an interesting operation in solidworks, whih is move/copy body which can keep the tube aligned when moved, there are tutorials on youtube showing how it works, you can take a look. the plugin is built on the same concept as I can see in their demo. The work flow can be done manually, it just takes time.
You may feel more comfortable to unbend the tube in Solidworks if it is your primary engineering app.