# Thread: New to Parametric Programming

1. ## New to Parametric Programming

Hi All, I'm a bit new to parametric programming, and here is my problem. I use a Thermwood CNC Router to cut masons mitres into kitchen bench/counter tops, the program I use, also has the ability to cut a curved end onto island/paninsula tops, but this function is not supported yet, I have looked through the program, and there are some parts of this function, but not all of the programming is complete. I need to be able to add the rest of the programming for it to work, there is mention of a chord (ie enter chord length) as the tops vary in width, the height of the curve should always be 10% of the chord (ie, 600mm chord, 60mm curve height, and so on), the chord will always be in the Y axis, the tops will also vary in length in the X axis. I'm not sure but after looking at a few posts, I think I might also have to learn about Macro's, as I am only used to G code. Any help with this problem would be greatfuly received.

2. Hi Doug,

If you can attach a drawing of your part, showing axes orientation, datum position, cutter path and 'user defined' dimensions, we can start working on building a program...

DP

3. Hi DP

I've been trying to attach a jpeg image, but I'm having a little trouble! the manage attachments button doesn't seem to work. Thank you for your reply, I have sent you a private message. If we can get this part of the program working, I'll buy you a carton of beer!

Doug

4. Originally Posted by dougdownunder
The height of the curve should always be 10% of the chord (ie, 600mm chord, 60mm curve height, and so on).

The maths involved to find the radius of the circle is as follows

r= (c^2 + 4*(h^2))/(8h)
Plug in your example dimensions 600mm chord and 60mm chord height.
r=(600^2 + 4(60^2))/(8*60)
r=780

Following is the same equation expressed in Fanuc User Macro language
#1 = 600 'Chord length
#2 = #1*0.1 ' Get the chord height

#3 = [#1*#1 + 4*[#2*#2]]/[8*#2]

if you were only cutting a segment of the circle, the start and finish point will have to be calculated.

Regards,

Bill

• Thanks Bill

Like I said in my original post I'm a bit new to this kind of programming! and I'm in a bit of a quandary as to where and how I must add this to the program we have, to get it to work, I'm only used to good old fashioned G coding in absolute, using a Wadkin CNC with a Bosch CC100 control.

I do have a word document with the program on, and I think I've highlighted the parts I need to look at. If you would like to take a look, please Email me!

When the program starts it askes, if the top has a double profile, then the length of the top (X axis), the width of the top (Y axis), how thick the top is , and the wasteboard thickness, and how much is needed to be trimmed off the lefthand end.

The program then goes on to ask what kind, joint is required on the LH end (ie Masons mitre male, Masons mitre female, straight cut, curved end, etc) it then askes the same of the RH end.

For tops with a double profile it will use both CW and CCW cutters, and cut just over halfway on the Y axisfrom both sides, as the tops are already laminated before the joints are cut on the CNC.

If you or anyone else could possably help me, I'll buy them a carton.

My Email is doug_n_jackie@bigpond.com

Regards

Doug