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### Author Topic: Tube/pipe coping or notching  (Read 15824 times)

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#### BR549

• 6,916
##### Re: Tube/pipe coping or notching
« Reply #20 on: October 29, 2010, 07:09:59 PM »
The math involved can be seen here:    Http://metalgeek.com/static/dan/derivation.html

It can be made simpler than I stated earlier as the formula calculates the Y as every 2 deg rotation of the profile so that will translate into a rotary A axis directly.Then it solves for a X displacement to create the profile.

(;-) TP
« Last Edit: October 29, 2010, 07:13:58 PM by BR549 »

#### Chestermarine

• 38
##### Re: Tube/pipe coping or notching
« Reply #21 on: October 29, 2010, 11:14:22 PM »
How about a paper template marking fixture, using a "laser pointer" to simulate tube #1, and a mandrel the same diameter as tube#2, with a paper wrapped around?

The laser "tube" can mimick any diameter, and be rotated by hand. The paper holding mandrel is on a pivot, to duplicate the required angle of intersect; both "tubes" centerlines intersect. Make as many pencil marks on the paper as you think necessary for the precision of the plasma cut. Also, the paper holding mandrel must be able to be rotated 180 degrees, to get the opposite side of the cut, depending on the type of intersect.

Use "teach mode", and a pointer in the spindle, to follow the paper template on the real tube, using the rotary table, and you get the real program, without math, or CAD programs. In addition, if desired, you could draw an "offset" line from the laser marked path, to account for plasma cut width. No math; no CAD programs; no file manipulation; no "Big Bucks!"

John

#### BR549

• 6,916
##### Re: Tube/pipe coping or notching
« Reply #22 on: October 29, 2010, 11:56:27 PM »
I think the idea was to input 5 values and cut the tube (;-)

(;-) TP

#### Chestermarine

• 38
##### Re: Tube/pipe coping or notching
« Reply #23 on: October 30, 2010, 02:31:26 AM »
Sorry about that. I missed the "input 5 values" part, but did read the "or relatively simple method to program in various tube / pipe fitting cuts. "
part.
Regarding the "Tubefit" site, and equation #9, they mention plotting templates, and using templates for the best fit. etc.
That equation #9 could be put into Excell, but de-bugging and testing could be quite a task.
Waiting for non-existant, or hugely expensive software could be a bummer.  Regarding a macro, Mach3 doesn't even have a reliable probing macro! This problem is orders of magnitude more difficult.
This tube intersect problem is a good one!  Good luck on finding a viable solution that meets your needs.

John

#### BR549

• 6,916
##### Re: Tube/pipe coping or notching
« Reply #24 on: October 30, 2010, 12:07:07 PM »
You would NOT run it as a macro. It would be a Parametric Gcode program that has a programable front end.

YOu would set the parameters such as

P1Diam
P2diam
Angle
Offset
Thickness

Then as the gcode file ran it calculates each point on the fly and does the move to the next point.

Mach does parametric Gcode VERY well.  Mixed VB gcode??? NOT so well(;-)

(;-) TP

#### Tony Bullard

• 156
##### Re: Tube/pipe coping or notching
« Reply #25 on: October 31, 2010, 02:35:23 PM »
"YOu would set the parameters such as

P1Diam
P2diam
Angle
Offset
Thickness

Then as the gcode file ran it calculates each point on the fly and does the move to the next point.

Mach does parametric Gcode VERY well.  Mixed VB gcode??? NOT so well(;-)

(;-) TP

I'm working on a VB program that writes G Code from the parameters above. The output looks like this.
G01A 123 y6.456
G01A 124 y6.789
the A is in degrees and they Y in inches. One problem-- how is the feed rate controlled? Also, How do you address the rotary axis? In degrees? Also you can't mirror the quadrents unless the pipes are at 90*and then not if the pipes aren't on the same center line.

« Last Edit: October 31, 2010, 02:38:56 PM by Tony Bullard »

#### BR549

• 6,916
##### Re: Tube/pipe coping or notching
« Reply #26 on: October 31, 2010, 02:55:25 PM »
Hi Tony, I have a parametric Gocde program already done and it works very well. I am waiting on permission from the math author to use his calculations.

THe equation that works the best is #6 from the deriative math.  It best suites the plasma process and straight cuts based on the 90deg angle of Z and XorY

A axis is controlled in deg of rotation.   YorX axis is controlled in programed units (inches or MM)

F###  sets the feedrate

Are you doing it as a VB macro or just using VB to create the Gcode file??

(;-) TP

« Last Edit: October 31, 2010, 02:56:58 PM by BR549 »

#### Tony Bullard

• 156
##### Re: Tube/pipe coping or notching
« Reply #27 on: October 31, 2010, 04:17:24 PM »
Hi TP, I wrote this program years ago in Quick Basic to print out wraparound temples. I’ve since modified it to write scripts to read into AutoCAD for printing and now it writes G code to a file. It’s still in QB and I’m working on getting it into a VB stand alone program. The problem with the feed rate is it should be in surface units per minute. The Y is in inches/min and the A I assume is in revs per minute. Apples and oranges. I’m just dry running it in Mach but a 2” pipe and a 6” pipe both take about the same time to run with the same feed rate. Humm. I’ll attach some files. See what you think.

Tony

#### BR549

• 6,916
##### Re: Tube/pipe coping or notching
« Reply #28 on: October 31, 2010, 04:53:40 PM »
Tony to run correctly you need to set the Axis diam correction to the same as the pipe diam. This way the A and X/Y axis feedrate willl be calculated better. AS is mach will only go as fast as the slowest component(normally A axis in deg)

Look on the settings page and input the tube diameter in the Axis DRO for corrections to apply.

I have a frontend macro that runs from inside the Gcode to program the parametric side  AND set the diam setting in the DRO

(;-) TP

#### BR549

• 6,916
##### Re: Tube/pipe coping or notching
« Reply #29 on: October 31, 2010, 05:12:45 PM »
Tony I ran your code and it looks good.  If you are interested you might want to consider building your application as a mach WIZARD. It could generate and LOAD your gcode program.

I have not been smart enought to figure out the Wizard creation so it is best left for others(;-)

(;-) TP