CAM Export questions

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ha4n
Junior Member
Posts: 11
Joined: Wed May 31, 2023 11:01 am

Re: CAM Export questions

Post by ha4n » Tue Jun 06, 2023 7:54 pm

HI CVH,

Thank you for your reply
CVH wrote:
Sat Jun 03, 2023 4:01 am
Husky wrote:
Fri Jun 02, 2023 8:13 pm
Total path / rapid path? In QCAD currently difficult to do!
Aren't rapid paths not simply on a dedicated layer after a toolpath is created ... ?
They are in 3D but that is summed just the same.
CVH wrote:
Thu Jun 01, 2023 8:52 pm
Not sure, I know of a long way.
If the G-Code is basic enough to import: menu CAM .. G-Code import...
Cutting and traversing are on separate layers.
OK, thanks

Rounded to two digits.
wycinanie frezem 44.cnc: traversing in 193 moves with a total length of 1446.38mm.
planowanie 44.cnc: traversing in 193 moves with a total length of 817.33mm.
Both cut 193 paths with a total length of 1086.58mm at FEED 60.

Traversing paths are reduced to 56.51% for the second file.
Remember that traversing is done in G0 mode or with the highest X/Y FEED available.
Diagonal this even exceed these FEEDs because for example Fmax1000 in X and in Y is about F1414 along the trajectory.

OK

This doesn't account for plunge down and retract.
For this we need to investigate the G-Code:
It retracts 193 times in G0 mode from Z-1.6 to Z10 or 193*11.6mm = 2238.80mm.
And it plunges 193 times in two steps, first to Z0.08 in G0 and then further down to Z-1.6 in G1 F600, again 2238.80mm.

If allowable the most gain in travel that can be made is in plunging down and retracting.
If the cutter doesn't collide with anything at lets say Z3.0 the vertical movements can be reduced to 1775.60mm instead of 4477.60mm.
The gain is here much more pronounced then with optimizing Start/End. :P

OK


I think that most machinist and businesses are interested in the estimated cutting time and not in the traveled distance.
This is even harder to estimate because we need to account for acceleration and deceleration time. e_geek

Fine, true but cutting parameters are actual not in my scope, but I understand


@ ha4n: May I remark that the plunging FEED is 10 times the actual cutting FEED. :shock:
In the end this will kill your cutter as it is slamming in full cut on your workpiece at 600mm/min.
Usually it is reversed: cutting FEED 600, plunging gently at FEED 60. :wink:
This kind of aggressive entry strategy may be required for surface hardened materials ... For the first handful of microns. :wink:

I check my cutting paraneters and will back to you 8)

Regards,
CVH
Many thanks

ha4n
Junior Member
Posts: 11
Joined: Wed May 31, 2023 11:01 am

Re: CAM Export questions

Post by ha4n » Tue Jun 06, 2023 7:55 pm

Hi CVH,
Fine, now I know
CVH wrote:
Sat Jun 03, 2023 4:42 am
Husky wrote:
Fri Jun 02, 2023 8:13 pm
Command IS? Don't know what that is ... :oops:
menu Info .. Total Length of Selection (IS).
Similar as Property Editor .. Total Length if and only if the selected entities are of the same type.

Regards,
CVH

ha4n
Junior Member
Posts: 11
Joined: Wed May 31, 2023 11:01 am

Re: CAM Export questions

Post by ha4n » Tue Jun 06, 2023 7:57 pm

Hi CVH,

Actual I have no Idea about this M's.
This are automatic exports from other software
CVH wrote:
Sat Jun 03, 2023 4:59 am
ha4n wrote:
Thu Jun 01, 2023 8:26 pm
My problem is that this software can't export to LinuX CNC, which I need. I got only Gcode.
wycinanie frezem 44.cnc
planowanie 44.cnc

Can you explain M2048 P0, M2048 P519 ... M2048 P711 in these files?

Regards,
CVH

ha4n
Junior Member
Posts: 11
Joined: Wed May 31, 2023 11:01 am

Re: CAM Export questions

Post by ha4n » Tue Jun 06, 2023 8:09 pm

Hi CVH,

all this is true.

Based on your cals total time is ca. 25 min where ca. 2 mins can be in my privat opinion reduced to 1 min, to get new total 24 min.
in 24h working machine it can be saving per day ca. 60 min.

1440 min per 24h per 25 min -57, 6 projects
1440 min per 24h per 24 min - 60 projects
2,4 projects more on one day = 2,4 *25min = 60 min

60/1440= 0,041= 4.1 % faster :) with one min reduction :P :twisted:

CVH wrote:
Sat Jun 03, 2023 6:13 am
CVH wrote:
Sat Jun 03, 2023 4:01 am
I think that most machinist and businesses are interested in the estimated cutting time and not in the traveled distance.
This is even harder to estimate because we need to account for acceleration and deceleration time.
In perspective, with infinite accelerations (... what is not of this world :lol: )

Cutting: 1086.58mm at FEED 60 >>> 18min 6.58sec
Traversing: 1446.38mm at FEED 1414 >>> Less then 1.5min (Assuming all at 45° with Fmax1000 in X & Y)
Traversing: 817.33mm at Fmax1000 >> Less then 1min (Assuming Fmax1000 in X or in Y)

Retracting to Z10: 2238.80mm assuming Fmax1000 >>> About 2.2min
Retracting to Z3: 887.80mm assuming Fmax1000 >>> Less then 1min
Plunging: Somewhat slower depending the pierce FEED for the last 2.4mm.

It takes more time to optimize G0 motions or write about it compared to the gain in fabrication time. :lol:
Still, optimizing is good practice when you need hundreds or more pieces.
Remark that I used moderate traversing FEEDs, my CNC engraver works fine with Fmax5000 reaching top FEEDs up to F7000.

Regards,
CVH

CVH
Premier Member
Posts: 3416
Joined: Wed Sep 27, 2017 4:17 pm

Re: CAM Export questions

Post by CVH » Wed Jun 07, 2023 5:44 am

Wojciech,

May I first remark that when replying one can quote a particular phrase or paragraph by first selecting it in the text of other replies.
This makes your reply more readable. :wink:
ha4n wrote:
Tue Jun 06, 2023 8:09 pm
2,4 projects more on one day = 2,4 *25min = 60 min
True, and then I quote myself:
CVH wrote:
Sat Jun 03, 2023 6:13 am
Still, optimizing is good practice when you need hundreds or more pieces.
Agreed for mass production of a certain piece.
But if that where 24-25 fully different jobs then the question remains if optimizing doesn't take longer than the gain for each.

Your example has 139 cuts and thus 138 traversing moves in between.
Given that each have a start and end, the number of combinations is binary: (139+138)^2 = 76729 possible path strategies.
Or comparing 76729 running sums with each 277 elements.
Retrieving 42507866 endpoints and defining 21253933 lengths equal to sqrt((x2-x1)^2+(y2-y1)^2).
That alone may take a while.

For sure there are clever ways to reduces calculations but they are all based on some assumptions that may or may not fit our purpose.
Husky wrote:
Fri Jun 02, 2023 9:37 am
38.44% less then your ~7016 mm path. Sounds already better to me then the 10% (actually 8.9%) optimization ...
ha4n wrote:
Tue Jun 06, 2023 8:09 pm
4.1 % faster
In my estimation the gain between diagonal traversing or straight is but a half minute.
This is at the moderate Fmax1000, double that and it is further reduced to about 15 seconds.
The gain in up/down to Z3 or Z10 is more pronounced: 2x 1.2 minutes or at least 2.4 minutes depending piercing.
That is still 1.2 minutes at Fmax2000 ... If there is a linear relationship at all ...
The traversing gain is then about 1/5 compared to the gain in Z motions.

When engraving text I tend to hover even lower than Z1 ... For each letter one has to plunge and retract.

And again: This is an estimation based on infinite accelerations ... :roll:
Somewhat longer paths may take as long as shorter because your router can't reach top FEEDs in limited movements.
It takes time to accelerate to Fmax and again to decelerate to dead stop.
While my engraver can reach top FEEDs up to F7000 for large traversings the average FEED in a job may even be less than F150.
ha4n wrote:
Tue Jun 06, 2023 7:48 pm
Maybe I not explained well. In my project I'm focused to get the shortest total patch because my router will engrave multiple times the same path (only lines).
Engraving a line in a single motion is in my book bad practice.
At one side you are climb milling for a nice cut while the other side is milled conventionally.
This is called 'Slot-Milling' and requires a specialized cutter and induces a fair amount of stress on your router because your router bit is for 180 degrees in contact with the material to cut. Although fine as rough entry move, the remaining is then milled conventionally/climb along the perimeter with a reduced contact rate, usually between 1/10 to 1/3 of the cutter diameter.
It is then preferable done slot by slot 'roughing' and slot by slot 'finishing' to reduce traversing.
ha4n wrote:
Tue Jun 06, 2023 7:48 pm
my router will engrave multiple times the same path.
When we start over cutting at the beginning of a job then a cutting strategy that ends near the start will be even shorter.
We could then eliminate 148mm traversing back to the beginning in 46.dxf ... -8.6 seconds at F1037 for Fmax1000 in X and in Y :roll:

I'll repeat myself:
CVH wrote:
Thu Jun 01, 2023 8:52 pm
For some reason QCAD doesn't reverse entities to see if there is a shorter route.
This may even be intended behavior.
When working in wood it is not preferable to work against the grain. :!:
And there are many other situations that blind optimizing to the shorted cutting strategy may not be preferable. :wink:
Because these are G0 motions the gain in fabrication time is usually too little to be relevant.

It takes about 5 minutes at least to change pieces, and about 10 minutes to manually change a cutter and zero it on a piece. :wink:
Compared to that it takes ages to fix a bad surface finish ... :lol:

Regards,
CVH

ha4n
Junior Member
Posts: 11
Joined: Wed May 31, 2023 11:01 am

Re: CAM Export questions

Post by ha4n » Sat Jun 10, 2023 8:13 am

CVH wrote:
Wed Jun 07, 2023 5:44 am
Wojciech,

May I first remark that when replying one can quote a particular phrase or paragraph by first selecting it in the text of other replies.
This makes your reply more readable. :wink:
ha4n wrote:
Tue Jun 06, 2023 8:09 pm
2,4 projects more on one day = 2,4 *25min = 60 min
True, and then I quote myself:
CVH wrote:
Sat Jun 03, 2023 6:13 am
Still, optimizing is good practice when you need hundreds or more pieces.
Agreed for mass production of a certain piece.
But if that where 24-25 fully different jobs then the question remains if optimizing doesn't take longer than the gain for each.

Your example has 139 cuts and thus 138 traversing moves in between.
Given that each have a start and end, the number of combinations is binary: (139+138)^2 = 76729 possible path strategies.
Or comparing 76729 running sums with each 277 elements.
Retrieving 42507866 endpoints and defining 21253933 lengths equal to sqrt((x2-x1)^2+(y2-y1)^2).
That alone may take a while.

For sure there are clever ways to reduces calculations but they are all based on some assumptions that may or may not fit our purpose.

Hi CVH thank you, I always learn a lot
Husky wrote:
Fri Jun 02, 2023 9:37 am
38.44% less then your ~7016 mm path. Sounds already better to me then the 10% (actually 8.9%) optimization ...
ha4n wrote:
Tue Jun 06, 2023 8:09 pm
4.1 % faster
In my estimation the gain between diagonal traversing or straight is but a half minute.
This is at the moderate Fmax1000, double that and it is further reduced to about 15 seconds.
The gain in up/down to Z3 or Z10 is more pronounced: 2x 1.2 minutes or at least 2.4 minutes depending piercing.
That is still 1.2 minutes at Fmax2000 ... If there is a linear relationship at all ...
The traversing gain is then about 1/5 compared to the gain in Z motions.

When engraving text I tend to hover even lower than Z1 ... For each letter one has to plunge and retract.

And again: This is an estimation based on infinite accelerations ... :roll:
Somewhat longer paths may take as long as shorter because your router can't reach top FEEDs in limited movements.
It takes time to accelerate to Fmax and again to decelerate to dead stop.
While my engraver can reach top FEEDs up to F7000 for large traversings the average FEED in a job may even be less than F150.
ha4n wrote:
Tue Jun 06, 2023 7:48 pm
Maybe I not explained well. In my project I'm focused to get the shortest total patch because my router will engrave multiple times the same path (only lines).
Engraving a line in a single motion is in my book bad practice.
At one side you are climb milling for a nice cut while the other side is milled conventionally.
This is called 'Slot-Milling' and requires a specialized cutter and induces a fair amount of stress on your router because your router bit is for 180 degrees in contact with the material to cut. Although fine as rough entry move, the remaining is then milled conventionally/climb along the perimeter with a reduced contact rate, usually between 1/10 to 1/3 of the cutter diameter.
It is then preferable done slot by slot 'roughing' and slot by slot 'finishing' to reduce traversing.
ha4n wrote:
Tue Jun 06, 2023 7:48 pm
my router will engrave multiple times the same path.
When we start over cutting at the beginning of a job then a cutting strategy that ends near the start will be even shorter.
We could then eliminate 148mm traversing back to the beginning in 46.dxf ... -8.6 seconds at F1037 for Fmax1000 in X and in Y :roll:

I'll repeat myself:
CVH wrote:
Thu Jun 01, 2023 8:52 pm
For some reason QCAD doesn't reverse entities to see if there is a shorter route.
This may even be intended behavior.
When working in wood it is not preferable to work against the grain. :!:
And there are many other situations that blind optimizing to the shorted cutting strategy may not be preferable. :wink:
Because these are G0 motions the gain in fabrication time is usually too little to be relevant.

It takes about 5 minutes at least to change pieces, and about 10 minutes to manually change a cutter and zero it on a piece. :wink:
Compared to that it takes ages to fix a bad surface finish ... :lol:

Regards,
CVH

Hi CVH,

Thank you. I always learn a lot.

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