Simplify3D question



  • I know this isn't really the proper place to ask this but I know there are a lot of smart guys here and I've asked elsewhere with zero results. Anyway, on to my question…

    Since upgrading to the Duet Wifi, seems all is working well and I'd like to test increases in print speed. I print a lot of bracket type parts, things with largish flat surfaces and through holes for bolts, etc. The problem is with an overall acceptable speed for the first layer, this speed on a small feature such as a 3.5mm hole, is much too fast. This leads to the hole not adhering and basically making a big mess. If I'm lucky, the print will turn out okay with a visible defect on the part surface that was on the bed. If I'm not lucky (which is most of the time), it will require restarting and slowing the print down. I've tried manually slowing the print down using the controls on DWC but this is tedious and the speed changes often are sluggish to respond.

    Does anyone know of a means of slowing down the print speed for small features on a part, preferably a means that requires no intervention.

    Thanks!
    Scot



  • You could try using a very low acceleration and jerk for the first layer this forces even small movements to take place quite gently. You could speed it up afterwards by sending the appropriate gcodes maybe by adding them manually to the gcode file or by using a postprocessor. You could keep your overall speed up so that long moves will accelerate though this isn't a perfect solution. I use very low first layer speed around 15-20mm/s, set in slic3r. My machine will do quite high speeds after that so I regain the time I lose on layer 1.



  • Thanks for the reply! I'm kinda new so while I get what you're saying, I'm not sure how to implement it. I don't believe S3D has the ability to change acceleration and jerk so this would have to be done in config.g? If so, how would you "undo" this for the remainder of the print?


  • administrators

    In the past I had to print quite a number of parts like that with 3mm and 4mm holes on the base, using Cura it has the annoying "feature" of doing all the inner perimeters before the outer perimeters, leading to small circles printed as a single outline with a fast move in and out - the same problem you are seeing. In the end I set my first layer speed to 10mm/s which was low enough to avoid the issue (in s3d its a % of normal speed but the same idea).

    DjD's idea of reducing the acceleration/jerk for the first layer, follwed by allowing to revert to normal for the other layers is definitely worth testing though. You would either need to do it manually by having the layer one settings in your "starting script" in s3d process settings, then revert to the normal settings by manually editing the gcode just after the G1 Z…. command to raise to layer 2. This will be a pain to do all the time so I would try the simpler option of a very low first layer speed first.



  • What I had in mind was using something like:
    M201 X100 Y100 Z100
    M566 X100 Y100 Z100
    (M201 is acceleration and M556 is jerk, you can enter these during printing in the console to experiment)
    In your start gcode which lowers acceleration to very low, and practically turns off jerk (this might be too extreme) then slice it, then load the gcode file in a text editor look for where the first layer ends which will be the first line with a G1 Z… command in it and then entering your normal values, mine are
    M201 X3000 Y3000 Z3000
    M566 X1200 Y1200 Z1200
    which then return the machine to normal printing.

    I just tried it and it does work, its almost too slow though and curves go so slowly that filament is oozing out and thickening them as it does, but long perimeters and infill go at a reasonable rate small details go very slowly. I think if you experimented with the values you might find a setting that worked.



  • Have you tried slowing the first layer down in the "Layer" section of the edit process settings in S3D? There is a first layer settings section in the where you can slow down the % of the first layer speed.



  • Thanks for the ideas, guys! I have tried slowing down the first layer speed but when the part is, say, 3" x 8" and there are only 4 holes, the first layer might take a couple of hours!

    DjDemonD, I think your idea is the best option and I'm quite sure even I can manage to figure it out! Thank you! For smaller parts, slowing down the entire first layer will work fine but for special cases, it would be worth the extra work. I'll give it a try this afternoon.


  • administrators

    Hi Scott

    Another option, given the size of the part, is to manually enter the different maximum acceleration/jerk lines in the console as the part is printing (you can use a macro, then its only 1 button click).

    You would then start slow, and once the perimeter is printed click the button and speed up to normal (else your bottom layer solid infill will also print slow)



  • Thanks, Tony…that also is a good idea and might be easier to use all the time.

    I'm looking at things now and realized I don't even have a jerk speed setting in my config.g file. What might be a good value to start with? I have a low end cartesian setup.



  • So far, this technique is showing a lot of promise! I've edited my config.g file by reducing the acceleration from 800 to 200 on the X and Y. I had no jerk settings in the config.g so I just put in a very low value of 100 on X and Y. I then created a macro that increases acceleration back to 800 and jerk to 200. I have no idea what to use for jerk so just went conservative. I notice that it behaves a little odd when rounding a corner so the jerk value must be off quite a bit.

    So, I start the print and it goes nice and slow. Once the small circles are done, I hit the macro and it speeds up…great! But, like DjDemonD mentioned, on corners and starts and stops, it seems like it extrudes too much plastic. It seems like the extruder thinks the print head is moving at normal speed but in fact, it's slowing down around the corners. Is there a setting in S3D that would fix this? I'm assuming it's a slicer issue?



  • Hi Scott,

    This is what I do with S3D to achieve what you are looking for.

    For the first few layers I have one process that slows downs things a bit to ensure I get accurate infill/overlap on holes along with a solid bed adhesion. - https://www.simplify3d.com/support/print-quality-troubleshooting/#gaps-between-infill-and-outline

    I then have another process which is essentially my "normal" print process.

    You can check out S3D's Tutorial Videos here (https://www.simplify3d.com/support/videos/) which describe these features. In particular, this video: https://www.youtube.com/watch?v=EbQfifnzL4Q&index=9&list=PLogLRK5xzNdieu445p2O7wODJpQBVf-Ss



  • If I am printing something which has small holes that need to be close to the exact model dimension, I switch over to the Prusa edition of Slic3r.

    Slic3r has a speed setting called "small perimeters" and basically any small hole (radius less than 6.5mm) will use whatever speed I set, which is usually 10-15mm/sec, and then I can keep my outline speed high and not have to ruin my print times, or find work arounds like above.

    I like s3d, but I wouldn't pay 140 dollars for it. It lacks too many basic features, so I find myself having to switch between slicers every now and then.



  • S3D i seem to remember allows you to print a model useing different process that can change by layer count so if i am correct (and I may not be) you could define a process for the first however many layer with the lower Acc/Jerk setting's in the start script and then change to process2 for subsequent layer which will reset the Acc/Jerk again with the Start script for that process.

    This will need a bit of research but think it would be feasable.

    Doug


  • administrators

    @ScotY:

    So, I start the print and it goes nice and slow. Once the small circles are done, I hit the macro and it speeds up…great! But, like DjDemonD mentioned, on corners and starts and stops, it seems like it extrudes too much plastic. It seems like the extruder thinks the print head is moving at normal speed but in fact, it's slowing down around the corners. Is there a setting in S3D that would fix this? I'm assuming it's a slicer issue?

    Have you tried enabling pressure advance in RRF?



  • @ThePigSlayer:

    If I am printing something which has small holes that need to be close to the exact model dimension, I switch over to the Prusa edition of Slic3r.

    Slic3r has a speed setting called "small perimeters" and basically any small hole (radius less than 6.5mm) will use whatever speed I set, which is usually 10-15mm/sec, and then I can keep my outline speed high and not have to ruin my print times, or find work arounds like above.

    I like s3d, but I wouldn't pay 140 dollars for it. It lacks too many basic features, so I find myself having to switch between slicers every now and then.

    Fantastic information - I am very much into slic3r prusa edition right now, its like slic3r but it works. This is an excellent feature which I did not know about and will try as soon as possible its a much neater solution than my jerk/accel idea.

    However to the OP I would consider a jerk value around 800-1200 to be "normal".


  • administrators

    I agree, the "small perimeters" speed in slic3r was very useful, and I miss it in S3D. I gave up on slic3r because it kept crashing, but perhaps I should try the Prusa edition.



  • The windows version I am using crashes around 10 times less often, it loads faster and it slices faster too, and I've been sending in bug reports which do get attention and fixes within a week or so, so its in active development.



  • Im glad I could provide some useful information!

    Prusa was trying to work together with someone from the original slic3r, but apparently that slowed development too much so he created his own branch. Recently the original slic3r has been getting updates, but I still found it was crashing too often, and the Prusa edition has some cool features like variable layer height and is updated more frequently.

    dc42, I had the same problem, loved slic3r but the constant crashing led me to s3d. I tried the Prusa edition a few months ago, and I have been using it ever since (I use both slic3r and s3d now) without a single crash.

    It's becoming embarrassing what s3d lacks, I really wish they would start releasing major updates again.



  • Okay so im running prusa slic3r 1.34 and cannot see the "small perimeters" options anywhere. There is an "external perimeters", and "perimeters"….. Where should I be looking?



  • try using dimafix, expensive but does the job.
    recommended to me by T3P3


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