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### Poll

#### Which cut strategy do you prefer?

use entered values, last cut whateveer is left
16 (69.6%)
Calculate equal depths of cut
7 (30.4%)

Total Members Voted: 23

### Author Topic: Depth of cut strategy  (Read 129924 times)

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#### Ron Ginger

• 925
##### Depth of cut strategy
« on: August 31, 2012, 07:51:34 AM »
I am working on the Newfangled wizards for Mach4. I have some mixed views from the early testers about the preferred depth of cut strategy.

The user will enter a total depth of cut and a step cut amount.
If the values result in an integer number of cuts use them- for example if the request is for .5 total cut and cuts of .1 then 5 steps of .1 will be used.

The problem is if the values don't make an integer number of cuts- for example, request .5 total in steps of .2.

Option 1) use the requested values and let the last cut be smaller- in the example make 2 cuts of .2 then the last cut of .1

Option 2) calculate a value so that all the cuts are the same, but less than the requested increment.

#### Brian Barker

• 3,854
##### Re: Depth of cut strategy
« Reply #1 on: August 31, 2012, 09:07:02 AM »
Best would be to do it in one pass
Fixing problems one post at a time

www.newfangledsolutions.com
www.machsupport.com

#### Hood

• 25,838
• Carnoustie, Scotland
##### Re: Depth of cut strategy
« Reply #2 on: August 31, 2012, 10:24:53 AM »
As you know Ron my preference is as requested by the operator  rather than the code thinking its smarter. It may well be sometimes but being a human I prefer to have the final say on things
One reason is I often profile shapes out of sheet material so say its 10mm thick I would likely programme to have a DOC of say 4.75mm which would leave a final of 0.5mm, this is handy for me, for example the last pass being 0.5mm means when the cutter comes round to fully cut the profile there is not a large "pip" left on the part and I dont have to resort to the grinder to remove it. Also the part is not so likely to violently swing round at breakthrough thus avoiding damage to the cutter, its not always easy to clamp for such situations and the part is either left to go free or gets held by hand..

Hood

#### mr.c

• 40
##### Re: Depth of cut strategy
« Reply #3 on: August 31, 2012, 10:40:13 AM »
Option one.

#### Hood

• 25,838
• Carnoustie, Scotland
##### Re: Depth of cut strategy
« Reply #4 on: August 31, 2012, 10:41:59 AM »
Option one.

Hood

• 4,912
##### Re: Depth of cut strategy
« Reply #5 on: August 31, 2012, 11:07:59 AM »
Hi Ron,
I voted #1
If the poll comes out near 50/50, would ib be too difficult to provide a selection option ?

STEP DEPTH   =    Equal Steps   or   User Defined.

Not wanting to make it any more complex than necessary.
Thanks,
Russ

• 4,912
##### Re: Depth of cut strategy
« Reply #6 on: August 31, 2012, 11:22:42 AM »
There's also the issue of wishing to define the last depth increment.
A pocket for instance where you'd like to specify the last pass depth.
.3 deep
.1 per step with last step .01 for a better finish.
would be -.1, then -.2, then -.29, then -.3
In other words, specify First past and Last pass and let the Wizard do the math.
Some of the other Wizards look this way.

Or would you just run another separate finish tool path ?

Thanks,
Russ

#### BR549

• 6,952
##### Re: Depth of cut strategy
« Reply #7 on: August 31, 2012, 12:07:04 PM »
I stand with Hood on this one IT should follow the programed sequences as best it can WITHOUT violating the input values. After creating a lot of conversational wizards that do this and working with machinist that use them I settled on the following 2 strategies that are the least objectable to the machinists. With cuts that do not end as an integer then the differential cut should be the first in the stack as it gives the machine room to correct a poor quality cut before it gets down to the finish cut.

Always follow the input by the operator as to steps and finish cuts.

2 ways to do it. If the cuts come out NOT as an integer then either make the FIRST cut the differential or overage or underage then complete the sequences as programed.(Hardest to do) program wise

OR  start the sequence at the differential value ABOVE the top of material so ALL cuts will be as programmed (easiest to program).

Machinist using conversational programming  like to KNOW that the wizard will DO  as they input NOT what the wizard thinks is right.

Yes it is splitting hairs sometimes BUT machinists can be a finicky lot and sometimes for GOOD reasons . SOME material tend to work harden and need to be cut exactly as programmed to work out right.

Just a thought, (;-) TP
« Last Edit: August 31, 2012, 12:10:16 PM by BR549 »

#### Sage

• 365
##### Re: Depth of cut strategy
« Reply #8 on: August 31, 2012, 03:35:34 PM »
I voted for number 1. For the same reasons as others have mentioned. Don't try to out think the operator.

Considering your example of .5 total depth with .2 DOC.
If you try to calculate equal passes you either end up with values that cannot be accurately achieved (like .5 / 3 = .1666666...) or more passes than are necessary (.5 / 4 = .125) when all you need is is to do two passes of .2 like the operator asked for and 1 finish cut of .1

As far as I've seen in other programs I set the depth of cut and if I'm not happy with the number of passes then I can do the math to adjust the DOC for less passes. The result is under my control.

Sage

#### zafarsalam

• 327
##### Re: Depth of cut strategy
« Reply #9 on: September 01, 2012, 08:52:13 AM »
I use mastercam extensively for generating toolpaths. It makes the depth cuts of equal value if they don't divide up to an integer value. A separate option is available for number of finish passes and the amount to cut in the finish passes.

Zafar