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1  General Category / Support and Bug Reports / Slitting saw on a small pinion - simulation trouble? on: August 19, 2015, 09:20:37 AM
Experimen ting with a 0.4 module 10 tooth pinion.

I suspect the cuts are going to be OK but the simulatio n has them misplaced relative to the image of the finished gear



see attached screen which also shows tool parameter s.

John Prentice

2  General Category / Support and Bug Reports / Tangential shaving clips an already machined face on: August 13, 2015, 10:41:37 AM
In tangentia l shaving I tend to cheat by using a "false" gear thickness to minimise cutting air during the to and fro X motion.

Even with a width that makes the cutter fully form the tooth for each tangentia l pass one hits trouble when moving from the upward facing face to the adjacent downward face. The cutter fouls the tip at one edge. This can be seen in



the relevant code snippet is

Code:
G1 Y-3.964  Z14.158  A30.114  F250
G1 X7.150  F200 
G1 Y-5.255  Z16.574  A35.717  F250
G1 X-7.150  F200
 
G1 Y-1.202  Z-0.406  A-1.200
 
G1 X7.150 
G1 Y-1.392  Z-4.742  A-10.061  F250
G1 X-7.150  F200 
G1 Y-1.704  Z-7.064  A-14.851  F250
G1 X7.150  F200 
G1 Y-2.223  Z-9.406  A-19.755  F250
G1 X-7.150  F200 
G1 Y-2.967  Z-11.769  A-24.821  F250
G1 X7.150  F200 
G1 Y-3.964  Z-14.158  A-30.114  F250

The line with blanks before it is the culprit. A and Z are going in a coordinat ed "straight line" with the centre of the cutter well beyond the blank at X=-7.15 but the cutter still clips the just machined tooth face.

With a given diameter of saw the problem can be avoided by stating the face width is bigger than it really is but this cuts air for both ends of every tangentia l shave  Sad

I think the change of code to

Code:
G1 Y-5.255  Z16.574  A35.717  F250
G1 X-7.150  F200
 
G1   Y0.0
G1   Z-0.406  A-1.200
G1   Y-1.202

G1 X7.150 
G1 Y-1.392  Z-4.742  A-10.061  F250

would always be safe wherever X ends when switching sides and will have negligibl e effect on overall machining time.

Sadly I can think of no easy way to identify this context for each tooth in a text editor loop so it's a Gearotic bug or an enhanceme nt request!

John Prentice
3  General Category / Support and Bug Reports / Tangential shaving clips an already machined face on: August 13, 2015, 10:35:46 AM
In tangentia l shaving I tend to cheat by using a "false" gear thickness to minimise cutting air during the to and fro X motion.

Even with a width that makes the cutter fully form the tooth for each tangentia l pass one hits trouble when moving from the upward facing face to the adjacent downward face. The cutter fouls the tip at one edge. This can be seen in



the relevant code snippet is

Code:
G1 Y-3.964  Z14.158  A30.114  F250
G1 X7.150  F200 
G1 Y-5.255  Z16.574  A35.717  F250
G1 X-7.150  F200
 
G1 Y-1.202  Z-0.406  A-1.200
 
G1 X7.150 
G1 Y-1.392  Z-4.742  A-10.061  F250
G1 X-7.150  F200 
G1 Y-1.704  Z-7.064  A-14.851  F250
G1 X7.150  F200 
G1 Y-2.223  Z-9.406  A-19.755  F250
G1 X-7.150  F200 
G1 Y-2.967  Z-11.769  A-24.821  F250
G1 X7.150  F200 
G1 Y-3.964  Z-14.158  A-30.114  F250

The line with blanks before it is the culprit. A and Z are going in a coordinat ed "straight line" with the centre of the cutter well beyond the blank at X=-7.15 but the cutter still clips the just machined tooth face.

With a given diameter of saw the problem can be avoided by stating the face width is bigger than it really is but this cuts air for both ends of every tangentia l shave  Sad

I think the change of code to

Code:
G1 Y-5.255  Z16.574  A35.717  F250
G1 X-7.150  F200
 
G1   Y0.0
G1   Z-0.406  A-1.200
G1   Y-1.202

G1 X7.150 
G1 Y-1.392  Z-4.742  A-10.061  F250

would always be safe wherever X ends when switching sides and will have negligibl e effect on overall machining time.

Sadly I can think of no easy way to identify this context for each tooth in a text editor loop so it's a Gearotic bug or an enhanceme nt request!

John Prentice
4  General Category / Suggestions for Future / Slitting saw cutting on: August 13, 2015, 10:05:49 AM
Cutting clock gears with thin slitting saws is very promising but the segmentat ion is hard to optimize. Too high a segmentat ion impacts cutting time badly. Here is a closeup with segmentat ion of 8



showing ridges that will impact friction of a gearpair.

How about adding another machining process for each tooth flank that has the cutter positione d, in X, on the middle of the edge of the wheel and does a Y move into the root generatin g the tooth face by coordinat ed motion of Z and A with the Y infeed?

If a low feed rate can be called up for this then a very smooth tooth can be made with little impact on the total cutting time.

This would produce a dished face in the dedendum but for thin gears and a reasonabl e saw diameter this would not be objection able. If one wanted to avoid the dish for cosmetic reasons say when cutting a small stack of gears, then the Y-depth could just kiss the root in the middle as the tooth flanks are probably flat in this area.

John Prentice



5  General Category / Support and Bug Reports / Re: What is the trick to getting my rotary axis to turn at a reasonable speed? on: October 22, 2010, 03:57:06 PM
IMO the best solution is for rotary axis CAMmed code to use inverse time feed mode. That way you get sensible coordinat ed motion of a move including a rotary axis.

John Prentice
6  General Category / Support and Bug Reports / Shaft sizes with imaginary gears on: October 05, 2010, 03:16:39 AM
Art, greetings

In 1.61 managed to get a 3 mm shaft for Master on an imaginary gear by setting the shaft size before generatin g the master. (The number looks as though it belongs by Adding Master Adding Slave buttons).

However on Generatin g Slave I always get a 5 mm shaft.

John Prentice

p.s. one does need to be able to have different shafts so the control should perhaps be used whenever one Generates and Adds.
7  General Category / Support and Bug Reports / Re: Imaginary gears do not seem to work except when they are 5 MOD on: October 01, 2010, 03:05:15 PM
(1) Thanks. That fixes it.

Perhaps a change in the DP control ought to clear the Master or perhaps better generate a new one automatic ally.

(2) I think there is a bug in shafts for Imaginari es. I cannot get a hole for the shaft in the master when exported as STL. The slave seems OK.

Best wishes - John Prentice

8  General Category / Support and Bug Reports / Imaginary gears do not seem to work except when they are 5 MOD on: October 01, 2010, 06:00:13 AM
I have tried imaginary gears but it looks as though that math is wrong for cases above and below MOD 5. The generated gears show no possibili ty on mating.  Win XP SP3, x86


Not sure about Gearotic version - cannot see where it would be.





This example is meant to be MOD 2.0


Best wishes

John Prentice

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