You are not logged in.

#1 2019-03-06 01:43:53

macdarren
Member
Registered: 2017-03-20
Posts: 411

Dynamic Lift Speeds

Question:  Does the computed dynamic lift speed only apply to the "slow speed" zone?
If so I am thinking that maybe the estimated completion times do not take this into consideration even once print is underway?

This came up as I was using Dynamic lift speeds and when I went from static speeds to dynamic the time calculation shown during the print
jumped from 2 hours to 5 hours .... understandable as my new peel speed was somewhat slow and I noticed on the Dashboard that the G-code
after the print was the big time suck.

I assumed that my super slow peel or at least the faster of my two speeds was basically being applied to the full lift.
My original formula did account for some changes in initial layers vs later ones and of course print area...but even my fast speed was not as fast as the non-dynamic 'Max' setting.
I was not terribly surprised but decided to let it finish.

So while it was printing I decided to come up with a formula that could do 3 speeds by keeping my initial two and then generating a negative number after the
the the platform had moved a full 2mm past the peel point, so that I could still do 6mm total lifts.  My thinking was that after 2mm, the negative number would then cause
nanoDLP to default back to the standard non-dynamic speeds....which is fine once the peel is complete it might as well move fast.

Then much to my surprise my print finished well under the estimated 5 hours it had shown for the first many layers well past the longer burnin layers.
In fact it completed in a little over 2 hours which is about what I initally expected..so maybe my new code is not needed if the dynamic
speed only applies to the 'SLOW' section.....just the calculations somehow don't consider this....I know that the ETA changes as the burnin are finished but in this
case the ETA and the G-Code time after print bar stayed quite high well past the burn-in.

On a side note the [[IsBurninLayer]] variable doesn't seem to work for me at least in the Dynamic Speed calculations...I assume it should return 1 or 0?

Offline

#2 2019-03-06 04:57:26

Shahin
Administrator
Registered: 2016-02-17
Posts: 3,541

Re: Dynamic Lift Speeds

Dynamic fields in general bypass all other fields for all layers. So zone would not affect it. [[IsBurninLayer]] is also should return 1 and 0

Calculating print time is a bit complicated as current implementation taking different strategies. Due to nature of NanoDLP fields it is very difficult to come up with good guesses.
1. If no data available, it just average previous layers time, it does not go into detail of each action. So during burnin layers you see very high time estimate but as it gets to end of print, it corrects itself.
2. If the profile used for another print, time spend for each layer will be considered. So it will be much more accurate but still if dynamic or syscall fields affect print much, estimate will be wrong.
3. If the plate itself printed before, time will be calculated based on previous print so estimate must be exact, except if you are using sensors to affect dynamic fields and etc.

Offline

#3 2019-03-06 07:12:40

macdarren
Member
Registered: 2017-03-20
Posts: 411

Re: Dynamic Lift Speeds

I have been looking at the G-Code sent and I now realize motion doesn't work how I thought.  (for instance I thought peeling had two different speeds close to the plate and then later after the peel while the printer was just rising) but I can see from the G-Code that there is in most profiles only one motion command issued and it is at 1/5 the decent rate.  I am going to try to work out some more complex Code to work
more like i think they should....I don't even know why decent speed and peel are related much less why 1/5 was chosen.

I think the field names and help are misleading especially for RAMPS users. 

I "think" I understand now what is happening and will do some testing to be sure....
Once I think I understand I will double check with you and maybe provide some amendments to the pop up help that hopefully make sense to everyone....
My guess is the descriptions and field names were designed around a different style printer using DLP of course and probably full RPi control vs the now more common LCD / RAMPS machines.
The result is things have been 'mapped' to work but now don't make total sense to someone without insight behind the scenes.

Thanks for all the help

Offline

Board footer

Powered by FluxBB