Author Topic: Engraving letters as pocket  (Read 390 times)

Offline glub0x

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Engraving letters as pocket
« on: April 29, 2021, 13:28:31 pm »
hello,
i have some trouble with cam bam trying to engrave letters as pocket.
If my letter has 2 parts or if i have several letters, my router keeps retracting up which makes engraving impractical.
the only solution i found that is totally impractical is to turn each letter in polyline and make a separate pocket for all of them... It then works doing the pocket one after another...

i have try the obvious "level first" or "depth first" option without success <-- this does not change anything which is weird to me
i also changed optimisation mode

i do not know what to do next ;(


Offline EddyCurrent

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Re: Engraving letters as pocket
« Reply #1 on: April 29, 2021, 16:10:20 pm »
Please attach the cb file you are using otherwise it's just guessing.
Made in England

Offline kvom

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Re: Engraving letters as pocket
« Reply #2 on: April 30, 2021, 14:08:42 pm »
Quote
totally impractical is to turn each letter in polyline

Assuming Truetype font, that's a pretty normal thing to do.  And unless the letters are more than twice the width of the cutter, a profile is better than a pocket here.

Offline glub0x

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Re: Engraving letters as pocket
« Reply #3 on: May 03, 2021, 12:42:14 pm »
Please attach the cb file you are using otherwise it's just guessing.
Trying to simplify my file to share with you i found that my "curvy" font was maybe too ambitious for me now.
So i switched to Arial and it works better but i still have some retracting up problem that i d like to fix.
I think there is 2 different kind of problems.
--> The bigger one you can see in the letter B of my file, it keeps retracting for some reason, it is much better if i tweak "max crossover width" but still not perfect.
--> The other one i think is visible in the letter i:  when it is done with one level, it retracts go back to the next lvl start up and plunge again. When really it should just change the start point and plunge...

I am still  very new to cambam so i probably missunderstood something !

Thanks for time and help...
« Last Edit: May 03, 2021, 12:44:49 pm by glub0x »

Offline pixelmaker

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Re: Engraving letters as pocket
« Reply #4 on: May 03, 2021, 14:29:38 pm »
Hello
it makes sense if you try different settings. There are always different ways to reach the goal in CamBam.

3 tips for the beginning.
1.) Set in the Configuration the "Diagnostic Level" to 4. Then the calculated milling times are displayed and you can see the optimization directly in CamBam.
2.)In the Machining folder in the drawing tree is the variable "Fast Plunge Height". This variable is set to -1 in your case, so CamBam moves at fast speed up to one drawing unit above the workpiece surface and then continues down with plunge speed. With your 30mm/min this takes time. Enter 0.1 there and CamBam moves down to 0.1mm above the start of milling in fast speed and only when plunging in plunge speed.
3) Stepover Feedrate is set to Plunge Speed, change this to Cutting Speed.

Then create a standard template from these values so that each new file receives these values.

Quote
The other one I think is visible in the letter i: when it is done with one level, it retracts go back to the next lvl start up and plunge again.
I don't see a retract there. Every level is milled without retracting.

Quote
it keeps retracting for some reason,

The least retracts are achieved with Cut Ordering -> Depth first and Optimisation Mode -> Legacy (0.9.7). Then all "B" are milled inside first without retract, then the "i" then the outside of the "B"
But this does not speed up the milling alot.

ralf

Offline glub0x

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Re: Engraving letters as pocket
« Reply #5 on: May 03, 2021, 19:17:59 pm »
Hello
it makes sense if you try different settings. There are always different ways to reach the goal in CamBam.

3 tips for the beginning.
1.) Set in the Configuration the "Diagnostic Level" to 4. Then the calculated milling times are displayed and you can see the optimization directly in CamBam.
2.)In the Machining folder in the drawing tree is the variable "Fast Plunge Height". This variable is set to -1 in your case, so CamBam moves at fast speed up to one drawing unit above the workpiece surface and then continues down with plunge speed. With your 30mm/min this takes time. Enter 0.1 there and CamBam moves down to 0.1mm above the start of milling in fast speed and only when plunging in plunge speed.
3) Stepover Feedrate is set to Plunge Speed, change this to Cutting Speed.
...

Thanks Sir, loads of good information here already saved 4 minutes out of 30. I am now in a hurry to test that on the cnc!
To be able to see the carving time is particulary appreciated:)

Some thoughts :
-->Strangely i see no difference in time with the "Fast Plunge Height" set to -1 / -0.1 or 0.1 but my machine is so slow to go down that it should save me some time ...
--> The legacy mode works well but it looks much more CPU intensive




I have another question that is not related to pocket :
My cnc is made out of an old 3D printer, works fine except it is small and slow. But my firmware seems not to like gcode g0 if the feedrate is not informed.
Typicaly cambam will export commands like G0 X23 Y23 when i would like it to say G0 F2000 X23 Y23 but i can t find where to change that. I ve messed with the post processor without success :(
Any idea?

Offline pixelmaker

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Re: Engraving letters as pocket
« Reply #6 on: May 03, 2021, 22:36:59 pm »
Quote
Strangely i see no difference in time with the "Fast Plunge Height"
If the rapid speed (G0) is not higher than the immersion speed there can be no speed advantage.
Quote
The legacy mode works well but it looks much more CPU intensive
Calculating the toolpaths happens in a few seconds for me. When the program is milled there is no difference because the number of lines in the G-code remains the same. Only the arrangement changes.
The font is of low quality. It has extremely many nodes. You can see this if you convert the "B" to a polyline (ctrl+P) and then double click. Each node means one line in the G-code. With a font you can only use fonts of better quality. You can reduce the nodes in CamBam only for polylines.

Quote
i would like it to say G0 F2000 X23 Y23 but i can t find where to change that.
Simply write F2000 in the line G0
Do not forget to save the PP
See attached images

ralf

Offline dh42

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Re: Engraving letters as pocket
« Reply #7 on: May 04, 2021, 02:36:46 am »
Hello

Quote
    Strangely i see no difference in time with the "Fast Plunge Height"

If you talk about the calculation time displayed in dignostic mode, some moves are not taken in account in the calculation ; it is the case for the rapid moves in Z direction.

' WARNING ; calculation is an approximation !
' Drill mop only return rapids value (even with spiral mill option)
' Trochopocket and trochoprofile plugin never return value
' Thread plugin never return value
' rapids lenght (and of course duration) take only the horizontal moves in account, so move to clearance plane duration is ignored
' toolpath lenght between 2 adajacent toolpaths is not taken in account if done in normal feedrate move.(but taken in account if rapid move)
' no way currently to distinguish leadin move and normal move, so leadin move are calculaded with the normal feedrate
' vertical moves (plunge) between levels are not taken in account
' The axes acceleration is not taken in account.
' rapids between 2 mop are not taken in account
' the rapids feed is hard coded ... something around 600/800 mm/min I think

++
David
« Last Edit: May 04, 2021, 02:41:15 am by dh42 »

Offline glub0x

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Re: Engraving letters as pocket
« Reply #8 on: May 04, 2021, 07:41:25 am »
The font is of low quality. It has extremely many nodes. You can see this if you convert the "B" to a polyline (ctrl+P) and then double click. Each node means one line in the G-code. With a font you can only use fonts of better quality. You can reduce the nodes in CamBam only for polylines.

I am working on a macbook of 2010  in a virtual machine. surely a bad setup...
My 30 letters text takes 1 sec to generate the gcode with Experimental and about 30sec with the legacy mode, quite a difference! Not a huge problem though...

More important, do you import specific font into cambam then?
I just went and choose the font cambam gave me Arial in that case...
@
Maybe it is better to use "line font" (not sure how it is called), that would be a font that is just a line instead of 2. A bit like the way i write., in that case i would only do a profile or 2 to engrave.

@David, Ok that makes sense, i need to check on the machine but clearly, with my setup going down takes time so it should make a difference.

Offline glub0x

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Re: Engraving letters as pocket
« Reply #9 on: May 04, 2021, 07:45:51 am »
Simply write F2000 in the line G0
Do not forget to save the PP
See attached images

ralf
But that may pose a problem to my Z move, the maximum move speed on my setup is about F3000 for X and Y and F120 for Z
NB With that i would only have one Search and replace operation afterward, already better.

Offline Dragonfly

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Re: Engraving letters as pocket
« Reply #10 on: May 04, 2021, 07:51:11 am »
G0 with 'F' parameter has no sense.
G1 with 'F' parameter has.

Offline pixelmaker

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Re: Engraving letters as pocket
« Reply #11 on: May 04, 2021, 09:08:40 am »
Quote
G0 with 'F' parameter has no sense.

Marlin GCodes

G0, G01 Linear Move

Ex:
G0 [E] [F] [X] [Y] [Z]

Exxx = length of filament pushed into the extruder between start and end point.

Fxxx = maximum speed between start and end point

Xxxx = coordinate for the x-axis

Yxxx = coordinate for the y-axis

Zxxx = coordinate for the z-axis


Quote
My cnc is made out of an old 3D printer

G0 with F parameter make sense if it is build from an old 3D Printer and it and uses Marlin based control.
However, many programs for 3D printers do not use G0. This does not mean that the controller does not understand the difference. Since G0 and G1 both have the same function, they can be used for different speeds.

Quote
But that may pose a problem to my Z move, the maximum move speed on my setup is about F3000 for X and Y and F120 for Z

If the speed for the Z-axis is limited in Marlin and if you use Marlin, this only means that higher values are limited. At least this is how it is in my Marlin controller in the CR10. On the Z-axis, the maximum speed should be 120mm/min even if F2000 is specified.
In addition, you can also change the limit values, either by flashing the software or by a line in the G-code.

The programs of my 3D printer start with the lines M201 and M203. These are the first two lines in the G-code. In CamBam they can be used as header lines fixed in the PP.

M203 - Set Max Feedrate
Set the max feedrate for one or more axes (in current units-per-second).
e.g.
M203 X500.00 Y500.00 Z10.00 E50.00 ;Setup machine max feedrate

ralf
« Last Edit: May 04, 2021, 09:28:06 am by pixelmaker »

Offline Dragonfly

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Re: Engraving letters as pocket
« Reply #12 on: May 04, 2021, 13:06:10 pm »
In G code standard G0 (G00) is 'Rapid move'. Which means move with maximum travel speed set for the machine. And it is not affected by 'F' (feed rate) command.
'F' is modal. It can be issued alone on a separate line and stays in effect until another 'F' value is given.
It affects the  G1, G2, G3 and other motion commands. All of them use the set feed rate value unless a different one is issued on the same line with the motion command. And the last 'F' becomes the valid one.

We are talking about machine controls which keep close to the standards. Not fancy variations for very specific applications.

Offline pixelmaker

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Re: Engraving letters as pocket
« Reply #13 on: May 04, 2021, 14:12:39 pm »
hello

glub0x has written:
My cnc is made out of an old 3D printer, works fine except it is small and slow. But my firmware seems not to like gcode g0 if the feedrate is not informed.
Marlin G- und M-Codes

What you write is correct as long as it is DIN 66025 G-Code.
If the machine is based on a 3D printer, you can assume that it is Marlin G-code. It is just a little different.
So the complete machine can be configured by M-commands at the beginning of each program.
All calibrations and settings that we know from the control system can be changed here with M commands at the start of a program.
In Marlin there are both G and M commands for 3D printers, but also for laser or milling.
The Z-axis is moved very slowly, it only has to move up a few steps at each new level.
Unfortunately, glub0x has not yet managed to tell us exactly what kind of controller he has. But the hint that G0 needs a feedrate tells me that it is Marlin controller.

ralf
« Last Edit: May 04, 2021, 14:16:23 pm by pixelmaker »

Offline Dragonfly

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Re: Engraving letters as pocket
« Reply #14 on: May 04, 2021, 15:20:30 pm »
Ok. Let's wait and see what it is.   ;)
Not GRBL anyway. It respects standard G0.