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### Author Topic: New burning machine idea  (Read 399 times)

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#### Chain9445

• 3
##### New burning machine idea
« on: January 16, 2020, 07:00:59 PM »
Hi all .
I am new to the Mach forum and am looking for input on a new machine idea.
I would like to build a machine for flame cutting circles in round steel plate. the plate is up to 3" thick and usually has an ID hole.
the machine would look something like a record player. With the plate being the record and the needle being the torch.
this would mean the axis would be the rotation of the plate and the angular movement of the arm carrying the torch.
this way the rotation of the plate should make a very round and accurate cut.

So I guess my first question is can Mach be configured to work in this way? there really isn't a x axis or y axis, they would both have to move if you were to try and make a straight line. The axis would have to be calibrated in pulses per degree. and if I wanted to cut a hole from 3" to 6" could a macro be written in Mach to do the trig to figure out the angular movements, and  maintain a constant surface feed of the torch as it moved from the small diameter to the larger diameter?
wow I can see a lot of math !
Regards

#### joeaverage

• 6,387
##### Re: New burning machine idea
« Reply #1 on: January 16, 2020, 08:06:35 PM »
Hi,
yes that would work but there is an easier solution.

If the plate sits still and a two axis machine (X and Y axes) moves the torch in a circle over the top of the plate.

Amongst the many things that CNC can do for you is move two axes (at right angles to each other) in a coordinated way to
describe a circle with very good accuracy.

Craig
My wife left with my best friend...
and I miss him!

#### joeaverage

• 6,387
##### Re: New burning machine idea
« Reply #2 on: January 16, 2020, 09:05:54 PM »
Hi,

Quote
if I wanted to cut a hole from 3" to 6" could a macro be written in Mach to do the trig to figure out the angular movements, and  maintain a constant surface feed of the torch as it moved from the small diameter to the larger diameter?
wow I can see a lot of math !

There is indeed some mathmatics....but you don't have to do it.
In Gcode there is a movement called G02 which does a circular move of programmable radius about a programmable centre
at a programmable rate, so easy!.

In addition to cutting circles you could program it to cut a mixture of straight lines and circles to any required shape you want.
Have a look at the 'Road Runner' example that ships with Mach3. The two axis machine I've described could cut the Road Runner
shape just as easily as a circle.

Craig
My wife left with my best friend...
and I miss him!

#### Chain9445

• 3
##### Re: New burning machine idea
« Reply #3 on: January 16, 2020, 09:16:27 PM »
Hi Craig
I understand I could do this with a regular burning table ,but the torch or tip not square or perpendicular to the material  for some reason you end up with a hole that is oval or trapezoidal. I need to have the holes perfectly round. the hole can be tapered or beveled but it has to be centered and round.

I have been thinking maybe the angular arm should be made as a linear axis , this would make the machine foot print larger, but less math.
Regards

#### BR549

• 6,952
##### Re: New burning machine idea
« Reply #4 on: January 17, 2020, 01:08:02 PM »
If ALL you were ever going to do is cut circles like you said then it would be a very simple machine with basically no high end math involved. There would be a central rotary axis (C) that simply rotates and a linear axis (X) that simply moves away from the center of the rotary. It's motion defines the diameter of the circle you wish to burn.

You could then create a simple WIZARD to define what size cirlce you need and enter in teh specs and it would create teh needed Gcode to burn teh circle.

G0 X0 C0
G0 X5.125  (sets teh diamter of teh circle to burn plus 1/2 of teh cut kerf)
M4 ( start the preheat )
M3 ( start teh cut )
G1 C 365  F10   ( move teh rotary axis 360 degrees ( circle) plus an overburn distance of 5 deg)
M5 ( shut off torch)

You could also do a leadin burn to avoid a dimple at teh pierce point.

Just a thought (;-) TP
« Last Edit: January 17, 2020, 01:10:09 PM by BR549 »

#### BR549

• 6,952
##### Re: New burning machine idea
« Reply #5 on: January 17, 2020, 01:14:32 PM »
IF you need to build a combo machine that can cut profiles , lines and perfect circles then you simply use a XYZ table and add the 4th axis (C) and have the best of both worlds.

(;-) TP

#### Chain9445

• 3
##### Re: New burning machine idea
« Reply #6 on: January 17, 2020, 01:50:53 PM »
Hi TP
Thanks for the input.
I like the simple code ,and the idea of a linear x axis  makes the math way easier.
not sure how the Wizards work but I will check it out.
Thanks again for the input.