Calculating points from a drawing.

[ladyz666]

I'm starting a CNC Machining course in the Fall, I'm trying to learn as much as I can before then. I've purchased CNC Programming Handbook by Peter Smid to learn what the various G and M codes do. Can anyone suggest a good book that has examples on how to calculate the start, end and tangent points on a drawing. If I can get the information off the drawing I can do the Trig calculations, I'm just not sure how to find the information.

The drawing that is attached appears to be a very simple piece to program, but I don't understand how you find the points for the inside pocket from the information on the drawing. For the start and end points of the .5 and 1 inch arcs can I use simple addition and subtraction to find them?

[Stu_M3]

Use polar co-ordinates to calculate points. see pic hope this sets you on your way.
Alternatively get a free cad system such as A9CAD and draw your compontent out and measure it.

Stu_m3

[lakeside]

you should put the 1" hole at x y 0 and start from there if your local vo-tec has a course in cad take it as for info on G and M codes just do a search on Google and you will find all the info you need

[Ozemale6t9]

Stu_m3 is on the right track, but you will need to recalculate as he has misread your drawing. I did the same at first, until I noticed your dimensions are diameter, and not radius.

regards, Oz

[Stu_M3]

sorry about that, still the same technique works.
Thanks Oz.

[Navigator]

Hi. At first you have to locate your part, define 0 point and than start calculations,I'd say it's one of the easiest ways

[gar]

060828-2128 EST USA

ladyz666:

You should not depend upon a CAD program to get you answers, but rather you should understand geometry and trigonometry.

There is an angle on your drawing of 5.711 deg this is from the arc tan of 0.1, but it is probably of no importance for your problem. What you need is the arc sin of 0.1 which is 5.7392 deg. This is the angle of the outside straight line with respect to the line between the centers of the two round holes assuming that this outside line is tangent to the two arcs, 0.25, and 0.50. The dimensioning implies that the pocket straight line is parallel to the outside straight line.

See if you can understand why it is the arc sin of 0.1 that determines the angle of the straight lines.

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