Creation of a Hole Model by Formula with Constraints

A hole model can be made more flexible with the use of formulas especially in the list of operations. To be able to create these formulas based on the holes' characteristics, whatever the hole shape, number of stages, and options defined, automatic referencing is required.

Hole Characteristics Referencing

The referencing in GO2cam is automatic and follows the following rules:

a letter to define the parameter or the characteristic (in blue below)
a number relative to the stage (in red below)

An illustration of a through hole with 3 stages is provided below to show the references:

H: height of the stage

In the operation list, Height (H) is replaced by Machining Depth (P).

D: diameter of the stage

Dc: diameter of the stage chamfer

Ac: aperture angle of the stage chamfer

R: radius in the bottom of the stage

For the tapped stage:

D: tapping diameter

Dd: drilling diameter

Hi: tapping height

Tp: tapping pitch

Do: diameter of the inverse chamfer of the stage

Ao: aperture angle of the inverse chamfer of the stage

There are also 2 more parameters applicable only for the operation list:

L0: total length of the hole

z0: value added at the end of path to make the path longer and avoid

The stages are numbered 1, 0, 1o

Definition of Hole Parameters

During the process of creating the User Hole, each parameter can be calculated according to a mathematical formula using other parameters. Syntax to respect: a formula must be written between quotation marks " xxx " the decimal symbol is the point. insertion of parameter: choose it in the list and it is automatically displayed in the field. You can also write it but you have to respect the syntax by writing it inside ‘hooks’ [xxx]. the formula must be mathematically correct, think about adding brackets for complex formula (multiple operators) all the mathematical operators are accessible (*+ - /** ), also the operators And and Or which enable to create complex formula, especially when defining the operation list.
Mathematical operators
sqr	Square	max	Maximum	acos	Arccosines	rnd	Random
sqt	Square Root	min	Minimum	asin	Arcsines	log	Decimal Logarithm
sin	Sinus	mod	Modulo	atan	Arctangent	sgn	Sign
cos	Cosines	exp	Exponential	^	Power	round	Rounding
tan	Tangent	Ln	Napierian Logarithm	abs	Absolute value	trunc	Truncation
				int	Integer value
Binary operators:		Comparison operators:		Priority operators:		Logical operators:
+	Addition	>	Superior to	( and )		OR	Logic Or
-	Subtraction	>=	Superior or equal to	Special Value:		AND	Logic And
/	Division	<	Inferior to	Pi		XOR	Exclusive Or
*	Multiplication	<=	Inferior or equal to			NOT	Logic No
=	Assignment	<>	Different from
==	Equality
Errors: If the parameter uses its own reference in the calculation formula, a ‘Self-referenced variable’ error is shown. Similarly an error is shown if the value defined for a parameter is too small. For example, the chamfer diameter is defined as inferior to the nominal diameter: Dc1 = " [D1] – 1.5 "

Formulas & Constraints in the Operation List

Parameters of the operations:

The parameters are divided in 3 categories:

Hole definition: execution of the cycle according to a constraint or not, unit and quality of the hole, definition of the machining depth. An interesting parameter is the weight, which enables to modify the positions of the operations. By default, all the cycles have a weight set to ‘0’, giving a weight of ‘1’ to an operation means positioning it at the last position (1 is heavier than 0). To position a cycle in the 1st position, define the weight to value ‘-1’.
Tool search: you can define a maximum value to the diameter.
Strategy: access to several strategy parameters of the cycle, such as the dwell and the Z offset. The incremental depth is interesting, you can base your calculation on a formula, for example in drilling deburring, you can define an increment equal to 1 tenth of the hole length. Please read above the chapter dedicated to formula creation.

Formula with conditions

Contrary to formula defined in the stages pages, these formula are not only calculation formula. Calculation formulas are possible, but here the great advantage is the ability to create constraints and then define an inter-dependence between several parameters.

Each dimensional parameter of the hole is defined with a reference, the complete list is given previously. The parameters described there are identical, except that we replace the stages heights (H) by machining depths (P)

2 parameters are added to this list:

L0: Total length of the hole. This value is given when applying a model on a part.
z0: over length value at the end of machining. You define this value in the hole options.

Thanks to the parameter ‘State’, we will be able to constraint the realization of a cycle by a formula.

Here is an example: a counter bored hole with 2 stages. We want to define a spotting operation to be done only if the drilling diameter is bigger than 10 mm.

For this, we first need to activate the check box in the line ‘State’ / column ‘Value’. Then choose the drilling diameter in the list of parameters, which is D1.

In the Formula field, enter [D1]>10.

In the list of operations, you will notice that a small white pointer arrow is positioned on the spotting icon, to indicate that this cycle is constrained by a formula.

When applying this model, simply fill the fields with the needed values and the operation list will be created taking the constraint into account.

Here, 2 holes with different values:

Counter Boring D14.5, (D1 >10mm) has a spotting operation
Counter Boring D8, (D1<10) does not have spotting operation.

Exercise

Here is an exercise to practice using the parametric formulas in the list of operations. We are going to create a hole model for the standard hexagon socket head cap screws M3, M4, M5, M6, M8, M10, M12, M16, M20 and more.

The hole is a through hole, counter bored, chamfered and tapped.

There will be 2 operations lists, one with conditions:

A. for counter boring which diameter is < to 18

B. for counter boring which diameter is > to 18.

Operations Lists
A. Diameter <= 18	B. Diameter > 18
Chamfering Spotting	Spotting
Drilling
Counter Boring	Pocketing
Tapping
	Chamfering / Interpolation

Here is the table of operations lists per counter boring diameter:

Screw	Counter Boring Diameter D1	Chamfering Spotting	Spotting	Drilling Dd0	Counter Boring	Pocketing	Tapping D0	Chamfer by interpolation
M3	8	X		X	X		X
M4	10	X		X	X		X
M5	11	X		X	X		X
M6	13	X		X	X		X
M8	18	X		X	X		X
M10	20		X	X		X	X	X
M12	22		X	X		X	X	X
M16	30		X	X		X	X	X
M20	36		X	X		X	X	X

▶️ Here is a video with the solution:

User Holes Conditions - Exercise-20240802-094010.png