Harmonic drive 4th axis build

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15 Jan 2023 20:43 #262060 by andypugh
You have
DEFAULT_ANGULAR_VELOCITY = 50.000000
So it seems that probe_basic isn't using that. It might be fixed? You would have to ask there.

The accelerations don't look low (I had already checked) but you could try pushing them a bit higher to see what happens.
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15 Jan 2023 21:10 #262065 by CNC_ANDI
yes i will open a topic in the probe basic thread for this.

ok i will test it again with the accelerations tomorrow.

thank you

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17 Jan 2023 19:44 #262264 by CNC_ANDI
So today i have tested the programm with double acclereations.... but nothing changes.

Simultan Programm is slow as before.

Changed the acclereations for xyz from 750 to 1500....

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17 Jan 2023 20:46 #262269 by andypugh
Can you explain again which code you are seeing the problem with?

In an earlier post I only saw one B axis move,
N81115 G93 B-982.046 F269.4382
And that isn't a combined move, so perhaps I am on the wrong track.
Anyway, without knowing where the B axis was before the move, it's hard to work out what the speed should be.

Then for example
N81175 G0 Z21.
N81180 G1 Z15. F1100.

So a move of 6mm in 1/1100 of a minute, ie 6600 mm/min
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18 Jan 2023 09:43 - 18 Jan 2023 09:49 #262327 by CNC_ANDI
At this code, the Movements are realy slow
 

File Attachment:

File Name: slow_2023-01-18.zip
File Size:708 KB

you can see it here -


but at this code:
 

File Attachment:

File Name: fast_2023-01-18.ngc
File Size:27 KB

the movements are fine.
you can see it on the same video at ~16:20min.
Attachments:
Last edit: 18 Jan 2023 09:49 by CNC_ANDI.

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18 Jan 2023 10:57 - 18 Jan 2023 10:58 #262330 by andypugh
I think that it must be due to falling back to the older single-segment lookahead.
It seems to be slower when doing combined Z and B moves and faster when Z is not moving.

Looking a the "slow" G-code it is requesting 207 degrees/sec      

delta ZZ vel (mm/sec)delta BB vel (deg/sec)Z11.104B-90.454F27344.8538    Z11.099B-90.859F30739.69230.0052.56164102-0.405207.4929Z11.094B-91.264F30702.33070.0052.55852756-0.405207.2407Z11.089B-91.618F35078.19650.0052.92318304-0.354206.9614Z11.084B-91.973F35055.96770.0052.92133064-0.355207.4145Z11.079B-92.329F35033.21990.0052.91943499-0.356207.8638Z11.074B-92.633F40846.69320.0053.4038911-0.304206.9566Z11.069B-92.938F40823.12950.0053.40192746-0.305207.5176Z11.064B-93.294F34968.8820.0052.9140735-0.356207.482Z11.059B-93.6F40770.33180.0053.39752765-0.306207.9287Z11.054B-93.855F48897.10910.0054.07475909-0.255207.8127Z11.049B-94.161F40724.67460.0053.39372288-0.306207.6958Z11.044B-94.467F40716.77050.0053.39306421-0.306207.6555Z11.039B-94.722F48805.88490.0054.06715708-0.255207.425Z11.034B-94.978F48779.42860.0054.06495238-0.256208.1256Z11.029B-95.234F48753.1790.0054.06276492-0.256208.0136Z11.024B-95.541F40603.31770.0053.38360981-0.307207.7536Z11.019B-95.746F60871.43590.0055.07261966-0.205207.9774

(Edit, this was a neatly formatted table when pasted from Excel..) 

The Z step-down is _tiny_ which is probably part of the problem. The system will only reach a speed which will allow it to stop before the end of the next segment (in case that is the last segment. This is what single-segment lookahead means) Can you persuade the CAM to make the Z steps 10x larger? That should help. 

To stop in 0.005 mm with an acceleration of 800mm/s the speed can not be higher than 2.6mm/s
To stop in 0.35 degrees with an acceleration of 4000 the angular speed can not be any higher than 50 deg/s 

(v^2 = u^2 + 2as equation)

Again, these tiny steps make no sense, the system would smoothly interpolate between steps 10 or 100 times bigger. 
 
Last edit: 18 Jan 2023 10:58 by andypugh.
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18 Jan 2023 16:05 #262347 by CNC_ANDI

Can you persuade the CAM to make the Z steps 10x larger?

i dont know how i can do that. i´m using Fusion360 for this code.

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18 Jan 2023 17:03 #262355 by andypugh
It got lost when the editor destroyed the data table, but every Z move in the slow section was 0.005 mm, ie 5 microns.

Googling on "Fusion CAM segment length" suggests that turning on smoothing might help.

 
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18 Jan 2023 20:40 - 18 Jan 2023 21:23 #262366 by CNC_ANDI
ah ok but smoothing i always have 0.01mm

edit: changed from 0.01 to 0.2mm now works faster. thank you so much!!!
Last edit: 18 Jan 2023 21:23 by CNC_ANDI.

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18 Jan 2023 20:56 #262367 by andypugh
Try 0.1mm and then try cutting air, just to see what happens.
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