Pattern takes long to process

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darkg
Junior Member
Posts: 14
Joined: Fri Mar 06, 2020 4:44 pm

Pattern takes long to process

Post by darkg » Fri Mar 06, 2020 4:49 pm

Hello!

I am trying QCAD Cam for some hobby cnc work. While limited, it does work somewhat.

Now I try to do a hole pattern. That is, several small holes. Many passes due to weak machine. QCAD takes a very long time to finish.

Is there a way to be smarter about it?

darkg
Junior Member
Posts: 14
Joined: Fri Mar 06, 2020 4:44 pm

Re: Pattern takes long to process

Post by darkg » Sat Mar 07, 2020 4:58 pm

20 contours à 5 passes took ~7 minutes to process. Is this normal? This is with offset.
A full grille pattern would be hours!

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Husky
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Re: Pattern takes long to process

Post by Husky » Sat Mar 07, 2020 11:38 pm

darkg wrote:
Sat Mar 07, 2020 4:58 pm
20 contours à 5 passes took ~7 minutes to process. Is this normal? This is with offset.
A full grille pattern would be hours!
Without seeing the actual drawing there is no way to tell you what is a normal process time and what not.

darkg wrote:
Fri Mar 06, 2020 4:49 pm
Many passes due to weak machine. QCAD takes a very long time to finish.
You have a weak machine but QCAD takes to long to process? That is a contradiction in terms! No software on earth is able to compensate for the weaknesses of a machine.
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darkg
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Posts: 14
Joined: Fri Mar 06, 2020 4:44 pm

Re: Pattern takes long to process

Post by darkg » Thu Mar 12, 2020 7:35 am

Husky wrote:
Sat Mar 07, 2020 11:38 pm
darkg wrote:
Sat Mar 07, 2020 4:58 pm
20 contours à 5 passes took ~7 minutes to process. Is this normal? This is with offset.
A full grille pattern would be hours!
Without seeing the actual drawing there is no way to tell you what is a normal process time and what not.
Ok, fair enough. Then, hours is not way off. That kind of is a major dissapointment. I guess I could tweak some kind of precision settings, but default values should work reasonable well, one might have assumed.
Husky wrote:
Sat Mar 07, 2020 11:38 pm
darkg wrote:
Fri Mar 06, 2020 4:49 pm
Many passes due to weak machine. QCAD takes a very long time to finish.
You have a weak machine but QCAD takes to long to process? That is a contradiction in terms! No software on earth is able to compensate for the weaknesses of a machine.
I apologize for being unclear. I certainly do not expect my software to compensate. I aimed to give context to why I'd want so many passes (which naturally will increase processing time). With many passes and many contours, time is simply a problem, surprisingly so.

CVH
Premier Member
Posts: 3478
Joined: Wed Sep 27, 2017 4:17 pm

Re: Pattern takes long to process

Post by CVH » Sat Nov 11, 2023 9:50 am

An older topic but there are things missing here.
darkg wrote:
Fri Mar 06, 2020 4:49 pm
Now I try to do a hole pattern. That is, several small holes. Many passes due to weak machine. QCAD takes a very long time to finish.
I presume you are not talking about the time QCAD/CAM needs to process your drawing.
You are rather speaking of the production time isn't it?

Production time does not depends on QCAD/CAM because it is your driver that executes G-code generated by QCAD.
And indeed 100 circular motions in 7 minutes is about 4.2 seconds for one circular motion or 21 seconds for one circular cut.
100 such cuts would take about 35 minutes.
About 4.2 seconds per full circle relates to R=1mm(F90) or R=2mm(F180) or R=5mm(F540) with Feed in mm/min.

Thus all depends on the programmed Feed, how fast you want that the machine travels in one minute.
F100 is half the feed of F200, F1000 will be 10 times faster than F100.
But the proper Feed/Speed depends on the substrate, ideal chiprate, spindel speed, mill type, mill diameter and the spindle power.
There is no straightforward answer to that.

If it mills fine but slow at F100 you may want to increase the Feed.
This until you remark that the cut is not clean anymore and then reduce the Feed to 80%.
Or until you remark that your setup struggles with keeping everything straight.
Or until your substrate melts or starts smoking. :lol:
Overdoing may induces bending stress on your setup, it will get louder, the spindle may throttle down by the higher power required.
In the end something must give away and then it is usually your mill that scatters in dangerous projectiles.

With circular motions there is another factor and that is the maximum acceleration of your setup (Usually a limit you can set).
Or how fast a motion in one direction can change to another direction.
For a circular motion the Feed in X continuously change form 0 to max and back while that for Y does the inverse.
With small radii your setup can not reach the demanded Feed below a certain diameter.
Remark that for holes this is counter productive because the router path diameter is the hole diameter minus the mill diameter.

Regards,
CVH

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