square root

[Rod]

Mike,

I've some experience with plasma cutter controls, but not PLC driven, true motion control cards. Part of our retrofit kit.

However, this intrigues me.

Unless I'm mistaking, you only need to calc one quadrant, store the 'step' values in a LUT (look up table) and flip X/Y axis values relative to center as required.

Quick idea, operator enters an X/Y center point and OUTSIDE radius value. Subtracting 1/2 the torch’s kerf value, the PLC does math for 16 points of ONE quadrant (3 degrees of resolution), probably adequate for holes up to 30 millimeter switches – a 64 side polygon.

Using engineering degrees (0 being right and 90 top), the torch moves in X+ , with Y equal to the hole center. This is Q1 (quadrant #1)

Torch down, assist gas on, torch is on, move to the next position in the LUT .
Meanwhile, (cool part here) the PLC swaps X+ to X-, relative to center and stores it in the same memory location (hang on).

As the torch steps through the LUT swapping values it reaches position 16.
At this point the PLC reverses looking at the LUT from Top-Down to Bottom-Up reusing the SAME memory space. (Cool Huh?)

Upon reaching position 16 the control tosses out position 1 of the next quadrant, as it is the same as the LAST position of Q1, BUT stores it anyway.

The next quadrant (Q2 – upper left): Swap X+ to X-. Y values are the same.
Repeat for Q3 and Q4 swapping the +- X/Y values

If a circle/arc is greater than preset radii then add more points/quadrant, IE 16 up to 1”dia and 32 up to 2”. Memory starts to go away REAL quickly.

Time to fire up Excel and start graphing. I’ll check my bench DL06 for mem space – see what I can see – used to write VERY tight code on the old Apple ][.

I would not build recipes unless you have a way to store them offline from the PLC – just do pre-calcs – it’s what we do anyway.


Any three non-linear points on a plane describe an arc, and by interpolation a circle - look up non-linear simultaneous equation. I had it but the 'puter died and I don't have hard copy - 5 lines of Basic code

Rod (The CNC Dude)

 

[leitmotif]

Mike doin that reply as I go.

Andy, I dont mind the cold, but the SNOW is a differnt story. Too messy. I do get a kick out of taking the kids sledding, but the other day I had to climb up on the roof to clean the sat dish. ~30' ft to the pavment...kinda spooky.
REPLY 30' is not spooky it will kill. In the snow it may be even worse won't kill just put you in a wheelchair. OF COURSE you had fall protection being a good elevator guy.

Dan, Your about on target. Some years ago I did a simmiler project for a friend. But that would only make gussets, one at a time. It was hardly worth the effort because he'd have to position the material for each cutout. Lots of scrap. He was happy though. They were all exactly the same, and he didnt have to dress/grind them.
REPLY The big drawback to mine is that the head rotates - must overcome cable and hose stiffness and dont get them all wrapped up ie max circular travel can only be 370 then has to reverse clear back to 000.

The problem with the money people is that I cant prove it will be worth it, but I still want to do it mainly to see if I can. If I totally fail, or it works really well and we end up using it often, I'll buy a professional CAD/CAM/Cnc control.
REPLY Well you don't know till you get the thing - prior to that all you can do is project / crystal ball. Set up a pilot and do a side by side - ie old way vs the wizbang way.

Back in 89' I bought a fax when few people had them. Days & days would go by between uses. Now we add paper every day. I'm hoping this might go the same way eventually.

One more thought IF you could put a stud weldor on this rig you could just weld studs instead of drill / tap etc etc. Now you have two tools in one. I have mixed feeling on stud welding but it is Great when they work. Have seen a robotic TIG torch - Navy used it to weld aluminum doors worked great as long as the fitups were tight - even with that problem and repair welding they still saved time.

 

[elevmike]

Dan,

Your clarivoint! Part of the plan is for one of the recipies to drill detents for studs. The studs would actually be placed with a hand held stud welder by feeling for the detent with the tit on the stud.

Rod, Thanks for the suggestions; I need to digetst them some.

 

[leitmotif]

Dan,

Your clarivoint!

Part of the plan is for one of the recipies to drill detents for studs. The studs would actually be placed with a hand held stud welder by feeling for the detent with the tit on the stud.

Rod, Thanks for the suggestions; I need to digetst them some.

REPLY Nahhh just lazy.
I try to get machinery to do my work for me.
However is this a billable item??
Dan

 

[elevmike]

Dan,

No it's not billable. It's a new toy for our shop. We dont really expect to be using it but once or twice a week, so I decided that it would be my wintertime pet project.

 

[leitmotif]

I was referring to the possibility of my clairvoyance being billable --
after all I am a good capitalist.

Dan