Jabbery

Thanks, yes I have used that feature. It does save a bit of time on the infill but only the infill. Using that feature the remaining features would all be printed at the finer layer height which is too slow. Infill layer thickness would though save more time if only the visible perimeters were in 0.1mm thickness, line thickness 0.4mm and infill 0.8mm (nozzle size dependent). For example on a stronger part with say 4 perimeters and 40% infill. Only 1 of the 4 perimeters would be at the fine height for cosmetic reasons. Many models I print have no requirement for inner features that can only be seen if you saw the part in half to be at super fine resolution. I rarely use transparent materials. Structurally there would not be a lot of difference maybe even a touch stronger. Transparent may actually look good this way. The overall print time would be greatly shorter and look as if the print was completely done at 0.1mm or layers at 0.1mm and infill at 0.6mm. Using Prusa Slicer for the feature type report. The time is not accurate but works for the example. (0.8mm nozzle, 1mm line width, sampled model uses 200M of 1.75mm filament) External perimeters roughly 22% of the print Infill roughly 20% of the print Features - everything else 58% of the print - this is where the time is saved. 0.1mm layer height - 42.9 hours print time 0.1mm layer height with 0.6mm infill layer height - 36.8 hours If the suggested feature is added 0.1mm external perimeter, 0.3mm features and 0.6mm infill - 17.7 hours and looks like the 0.1mm quality. 0.1mm external perimeter, 0.6mm features and infill - 16.6 hours and looks like the 0.1mm quality. That is a 55% time savings for only infill adjustment or you could roughly print 2 models in the same time frame and they would look like the higher resolution. Its also a 61% time savings over everything at 0.1mm. External perimeters would always have to be printed first to avoid collisions and once it matches the overall height of the features then the features would print, same again with infill if that is also a different height. i.e. 0.1mm external layer,0.3mm features layer, 0.6mm infill layer. This would avoid collision movement calculations and possible nozzle shape issues. It would really be the same process as the infill every 2nd or 3rd layer but with external perimeters. It would have to allow for the full range of devices, i.e. 1mm nozzle and 0.05mm layers so 15 external layers to one internal layer

Hello, A feature suggestion to make faster and better looking prints is to adjust layer height on visible surfaces while leaving layer height on inner surfaces. In the cura preview this is red in color that I am suggesting to adjust for finer layers. Example, with a 0.8mm nozzle one could have inner print areas at a layer height of 0.6mm while setting the visible surfaces to 0.1mm. On a layer change cura could adjust the layer height and print the visible (6 layers in this example) at 0.1mm and then continue from that final nozzle height at 0.6mm for inner areas and infil. If one had a cube with a hole in it. The outer visible wall of the cube would be at 0.1mm as well as the inside of the hole. A bit of caculating is needed of course for odd heights like 0.65mm layer height and 0.15mm outer wall height would be 3 layers of 0.15 and 1 layer of 0.2. This would greatly cut printing time and have a pleasing looking print.

I think I tried that but I will give it a shot over the next 24 ish hours, I have a 24 hour print running now.

Ah Jerk is a misleading term it is actually instantaneous speed change but that does not really explain it either. Weird term, I see it is actually a minimum target speed to decelerate to before a direction change to reduce stand still time and offload the amount of side energy on the frame/structure during a path change..

Thanks JCD, I seen that item and its information is not clear as to exactly what it does, I will test it when I have a moment. I had to complete that project and move on by doing 2 different models in F360. I did however run a number of other tests that are all inconclusive as per the cause of the problem. I attempted to eliminate something about the printer as well as the slicer. In testing multiple slicers there was variation in the inner perimeters but none were correct. I also tested multiple speeds as a possibility it was caused by too much acceleration causing deceleration and tool direction change to magically overshoot predictably. Was only a guess since I do not exactly know how acceleration and jerk completely work. My assumption is acceleration is both acceleration and deceleration ramp speed and jerk is an added factor to maybe deceleration on a sharp direction change to not jolt a weak frame.

Hi JCD, I configured as you suggested, with the flow back to 100% the outside perimeter is exactly 100mm. The inside perimeter has some variation of 92.3 - 92.66, back to the 0.94 - 1.3 mm off.

That was the latest test version I just hit save on for you. Originally the infill was the default as per a previous message of settings. Concentric was tested to see if there was an issue with the diagonal lines causing extra filament flow buildup pushing out the perimeter. I had noticed on a print or 2 that infill often has a bit of buildup at the start of the path. On the cooling fan I actually have no idea on ABS but I have had the best success with that setting. I basically searched the internet for settings for ABS and found 30-100%. What setting for cooling and retract would you use?

CFFFP_100x100x3mm test.3mf Here is the latest copy I was messing with. I have a brim 8mm outside to make the ABS stick Measurements I took were on the top 2mm to eliminate any 1st level/brim errors.

On this project no. I have had the same difficulty with PLA on other projects, they were also more simplistic like simple mounting plates so it was no problem and low risk of error to re-draw the model for printing or machining. This project has multiple items that mount on X, Y and Z axis (no diagonals thank god). The final part will be both printed in ABS and machined from Aluminium. They want both. So we thought we would just work with the end material to fine tune settings.

Just a point of interest and who knows it could be a trick. The latest Makerbot commercial in Youtube they focus on their printers/software do not have this problem. They show a part printed on their printer and a competitors printer that a large bearing fits into the part, the bearing fits in their model and not in the competitors.

I ran 3 test prints of the 100mm x 100mm box with a cutout of 93.6mm. I used 93.6 because the remaining border is 3.2mm is 8 lines exactly at .4mm line width, with offsetting inner and outer tool paths of 0.2mm there is 7 lines exactly remaining. Measurements should be outer 100mm, inner 93.6mm Note: The initial test at 100% flow the outer measurement was 100mm, filament feeder is calibrated at 100mm of feed with calipers. Gcode was generated twice for each infill pattern, flow rate was adjusted at the printer. Cura Settings: Layer Height 0.2 Initial Layer Height 0.3 Line Width 0.4 Nozzle 0.4 Wall line count 2 Top/Bottom pattern Lines Infill Density 20% Infill Pattern ZigZag Retract on 4.0mm Build Plate Adhesion Brim Material ABS Flow Rate 90% Model outer perimeter measurement 99.47 mm, inner perimeter 92.45 mm Changed Settings Top/Bottom Pattern Concentric Infill Pattern Concentric Same Everything else Model outer perimeter measurement 99.6 mm, inner perimeter 92.8 mm Changed Settings Top/Bottom Pattern Concentric Infill Pattern Concentric Flow Rate 85% Model outer perimeter measurement 99.4 mm, inner perimeter 92.9 mm In all flow rate adjusted prints 1 corner (start/stop) did not correctly form. Inner perimeter still maintaining a 0.8 - 1.15mm undersized. A flow of 85% showed clear signs of under extrusion, 90% flow only showed under extrusion on the start/stop corners.

Oops I should have seen that since I even calculated it. I was following the same order as the outer wall I suppose. I'm not sure I follow the thought of extrusion seeping into the open space. If the amount of space to fill is calculated and the feeder is calibrated the overflow should be minimized (assuming exactly 1.75mm filament). Seeping by 0.2 mm or half the line width would mean the seeping causes the extruded line to be 0.6+mm wide without losing the layer height. The actual measured inner space is 92.75 mm measured on both X & Y in the corners and in the center. It should be 93.6 which makes the overflow 0.85mm which is an full line width on each side. I will do a test print later today with the flow rate set to 90% to see how this changes the inner space, 90% should under extrude. Looking at the gcode correctly now I clearly see the inner perimeter is compensated.

Thanks, excellent explanation and great area to explore. It does not look like that is the case in my cura gcode file. I verified the cura 4 settings and it is 0.4mm line width,2 perimeters,100% initial layer line width. Filament feeder is calibrated with 100mm of filament feed. No visible over extrusion. this is a 100mm x 100mm as I mentioned above box that is 3.2mm wide and 3mm high. Basically a hollow box. 100mm with 93.6mm empty space. ;TYPE:WALL-OUTER G1 F3000 E160.37867 G1 F1800 X103 Y197 E164.97456 G1 X197 Y197 E169.57044 G1 X197 Y103 E174.16633 ; - 94mm wide G1 X103 Y103 E178.76222 G0 F3600 X103 Y103.2 G0 X102.5 Y103.2 G0 X102.572 Y197.428 G0 X199.33 Y199.33 G0 X199.8 Y199.8 G1 F1800 X100.2 Y199.8 E183.6319 - outer perimeter is 99.6mm which is correct compensation for 0.4mm line G1 X100.2 Y100.2 E188.50158 G1 X199.8 Y100.2 E193.37126 G1 X199.8 Y199.8 E198.24095 G0 F3600 X199.6 Y199.8 G0 X199.4 Y199.4 ;TYPE:WALL-INNER G1 F1800 X100.6 Y199.4 E203.07152 G1 X100.6 Y100.6 E207.90208 ;- 98.8 G1 X199.4 Y100.6 E212.73265 G1 X199.4 Y199.4 E217.56322 G0 F3600 X199.33 Y199.33 G0 X102.572 Y197.428 G0 X102.53 Y102.53 G0 X102.6 Y102.6 G1 F1800 X102.6 Y197.4 E222.19822 G1 X197.4 Y197.4 E226.83322 G1 X197.4 Y102.6 E231.46822 ; - 94.8 - incorrect should be 100 - 3.2 * 2 + 0.4 = 94 G1 X102.6 Y102.6 E236.10322 G0 F3600 X102.21 Y102.21 This is where I got the idea inner perimeters was not compensated. Outside measurement = 100mm Inside measurement = 100 - 3.2 - 3.2 = 93.6 but with tool path compensation it needs an extra 0.4mm = 94.0

This is true it is the inner perimeters that I am having a problem with. Outer perimeters seem to be compensated. To test Draw a box 100mm x 100 mm (larger is easier to see the error) Draw a box inside (offset) 90mm x 90mm This will leave you with a 5mm wide path around the perimeter Extrude this 5mm path 3mm (for fast print) Measure the X and Y outer perimeter. If your printer is tuned it will be exactly 100 x 100. Measure the inner space, it should be 90mm but it is not! It is out 1 filament line width (1/2 width on each perimeter wall). Print this part in different line widths, we are only dealing with X and Y so far. Second test: - now adding Z to the test. Draw a solid block say 20mm x 20mm and extrude it 20mm so you now have a solid cube. Cut away on X and Y axis a 10mm x 10 mm box centered. Again you now have external and internal perimeters you will find the internal perimeters are off by 1 line width on X & Y and 1 layer height on Z. Your hole will if you are using 0.4mm line width be 9.6mm not 10. Print it in different layer heights. i.e. draft at 0.3mm height for speed then 0.1mm for final version. What use to fit no longer fits. That is fairly easily correctable assuming you always print with a 0.4mm nozzle with a 0.4mm line width and say 0.15mm layer height well assuming you have nothing that is diagonal. Change your nozzle, layer height or line width, your modeled correction factors for 0.4mm (0.2mm on each inner perimeter) are now wrong again your back to not having a 10mm x 10mm hole. Now add Z axis.... vary the layer height, set adaptive layers where you have nooooo idea how to corect for layer height. Using the CNC example, if you slice (cam to generate gcode) use a 12mm endmill to cut a hole that is 50mm x 50mm in size, you get a 50mm hole, if you slice again with a 25mm you still get a 50mm x 50mm hole. The tool size is compensated for by the slicer (cam software). Ignore the issues with the corners on a CNC since larger tools will create larger radius. We talking about inner perimeter compensation for the tool (line width/layer height) Now lets get slightly more complicated, Draw a post that is 10mm in dia and extrude it 20 mm solid. Our goal is to insert this post into the next part. Draw a hollow tube 15mm in dia with a 10.1mm (some wiggle space) hole, the post will not fit. The post has an outer perimeter so it will be 10mm in dia, the tube will have an inner perimeter so it will have a 10.1 - 0.4=9.7mm hole, no fitty. Now lay it down so your dealing with X/Z axis, both layer height and line width. On the X/Y axis inner perimeter you are out on each perimeter by the line width / 2 and on the Z axis it seems (not fully tested) you are out by 1/2 the layer height on each side of the perimeter. Now build an object that has 20 different faces that connect with other parts crossing multiple axis. And to get really twisted with how to compensate, draw a diagonal channel like a cylinder and a key-way through an object, Z/Y and Z will be inaccurate and basically impossible to compensate, guessing starts and many model re-prints to get it right.

Thanks for the idea, we just started doing this in F360 using a user perimeter to offset inner perimeters so we can set it to zero for other processes but it is no where near as simple as that in the modeling stage. It does seem like a lot of extra work that can get very complicated with many variable slicer settings making this impossible to do outside of the slicer. It seems a little odd to me that the slicer does not reproduce dimentional accuracy and it has to be manually adjusted causing all types of issues with items like adaptive layers that will then throw any manual adjustment out of wack. The slicer is the only program that knows all the parameters at the layer like nozzle size, layer height and there the actual inner perimeter is. As a modeler I have no idea what layer height, nozzle size is going to be. As an example, if I draw a square hole in an object that is 10mm x 10mm I would expect it to be that size no matter what the slicer settings are changed to (nozzle size, layer height, adaptive layer etc). On all CNC machines I have worked on this is true. In another example, if I am modeling a part to be machined out of steel and do all prototypes in plastic I would likely use a huge nozzle for high speed in prototyping. Once the prototype passes I would run it with a smaller nozzle in 0.1 layer height for proof and acceptance of the client prior to cutting it out of a expensive piece of steel. Adjusting the model constantly gets very complicated and introduces opportunities for errors negating using 3D printers as viable prototyping devices.

Hello, I have been doing some testing of 3D printer in respect to modeling in a less expensive material first and once perfected using more expensive materials like Aluminium or steel on a milling machine. I have found that a model made in F360 needs to be different for a 3D printer and I'm not sure if there is a correction factor to allow the same dimentionally correct model to be used for 3D print or milling. In a very simple test, I made a coupling for steel square tubing that is 31.7 mm outside size tubing, I modeled 31.75 mm inside with a 3 mm wall thickness and the coupling would not go on the tubing. I found the inner perimeter size to be the nozzle size smaller than the actual draw model (0.4 mm) suggesting inner perimeters are printed with the center of the nozzle. Thus forcing the model to be adjusted for 3D print and not usable for machining (or at the very least more complicated). Note the outer perimeter is exact suggesting the nozzle path is adjusted for extrusion width. Any suggestions on what to do? Thanks