[Solved] Can you force printer to avoid turns during print?  

RE: Can you force printer to avoid turns during print?

A different approach that I thought of (more of a kluge...) is it sounds like you want something like the grid infill exposed top and bottom. You may be able to model that section of your part to be solid and then use a modifier in Plicer to set the infill to grid and set the top and bottom layers to zero so the infill shows, and then set the infill pattern angle to what you want. The tricky part will be figuring out what infill percentage will give the grid spacing that you require.

RE: Can you force printer to avoid turns during print?

Wait... What is the grid spacing you want? 0.25mm? Are you using a smaller nozzle than the standard 0.4mm (that usually prints at 0.45mm extrusion width), or are you expecting the holes to be smaller than your extrusion width?

RE: Can you force printer to avoid turns during print?

Short answer is NO.

Longer answer, you can't tell the slicer to not make turns. It has to have that ability to work and to do things like infill, move sideways, draw the part perimeter, etc. A turn is a basic function, and the number of turns is dependent on part shape, extrusion width, holes in the part, infill type, etc.

You can manually modify a .gcode file, but doing so is tedious and can easy end in a corrupted file that breaks something; and can even damage the printer (damage is hard to do, but possible).  You can also create scripts and software to modify the .gcode, but again, needs to be done carefully.

Yes, the printer can extrude across prior extrusions. Grid infill does this, as does triangle and star patterns; other infill might also cross from time to time. Even linear infills overlap perimeters an amount set by the slicer to ensure adhesion.

Print 0.2 mm layers with 0.25 mm nozzle is pushing the limits of the technology. 

I suspect what you are fighting (no pictures so we have to guess at what you are trying to do) is the simple fact FDM printers can't print a corner in free space. A corner must have a prior layer to make the turn.  What happens is filament gets extruded, never fully hardens as the nozzle moves into the turn, and the filament simply stretches around the corner and you get a triangle shape instead of a square shape.

Slowing the print down to almost nothing can help, but so far I haven't seen any working solution to this problem except soluble supports.

RE: Can you force printer to avoid turns during print?

@sembazuru

Thanks -- I do have a .25mm nozzle and I am using the detect thin wall setting to get it to print single width walls...

I have had a number of prints work well with the .25mm nozzle printing .25mm wide elements .25mm apart (elements are .2mm thick, with horizontal and vertical lines on different layers. I am using .1mm layers so printing two layers horizontally and 2 vertically, plus one more border around the whole thing as a top layer).

However, my recent print is not working (getting unreliable y-axis printing / shift, wonky lines, etc...) and it seems like it is because of the way the design is getting sliced. I leveled and recalibrated the printer etc.. and did some tests of simple parallel lines .25mm wide, .25mm apart, and 1mm tall (so 10x print layers) and they were perfect.

RE: Can you force printer to avoid turns during print?

The attached is what I am trying to print... I have played around with this and tried a number of different things (e.g., in the attached I manually created interconnecting elements to try to encourage the printer to follow a certain path) -- I will try slowing the printer speed down... 

RE: Can you force printer to avoid turns during print?

I also attached a picture of a recent successful print that was doing more or less the same thing -- .25mm wide elements .25mm apart .2mm thick with horizontal and vertical elements on separate layers to avoid turns. This was a larger overall print (and simpler in some ways) so I think that was why it worked better... The bottom walkway is my print (the top one is photo-etched brass for comparison). These are detail upgrades for N-scale trains...

RE: Can you force printer to avoid turns during print?

ZIP and post your part (the STL) so we can look at what you are trying to slice.   What the photos show shouldn't be that difficult.  

RE: Can you force printer to avoid turns during print?

Thanks very much everyone for offering your expertise / help...

Attached is a .Zip file with two versions of the STL -- one with an attempt to force the printer to follow a specific path (basically extra elements in the middle layer) and the other with the basic elements I think I need.

RE: Can you force printer to avoid turns during print?

@tim-m30

Your infill mesh results are really amazing... I will definitely need to play with that approach...

RE: Can you force printer to avoid turns during print?

@tim-m30

Tim -- can you tell me how I use infill to print this? For example, how do I setup so that the printer does not print a top layer to cover the infill...?

I assume that I basically create a full solid flat element that is the total surface area of the walkway I am trying to create and use infill to create the mesh within the main surface area.

Thanks in advance!

RE: Can you force printer to avoid turns during print?

You can set top and bottom layers to zero and that will reveal your infill.  If you only want to reveal certain parts of the infill you can use a modifier to set the top/bottom layers to zero only in the area the modifier covers.

RE: Can you force printer to avoid turns during print?

@neophyl

Thank you -- got this to work... initial attempt is not beautiful or anything but will need more time to tweak settings.

RE: Can you force printer to avoid turns during print?

Thanks everyone for your help so far.

I have been a bit slow posting in this thread since my printer was giving me far bigger problems with a y-shift that was messing up all my prints. Turns out the little screw that holds the gear tight to motor was loose...

Fixed that but now I am back to the original problem -- the horizontal / shorter lines are either being printed incomplete or coming out somewhat diagonal if I put interconnecting elements to force the printer to follow a path. I tried slowing down the printer and this did not eliminate the problem (I cannot tell if it even helped).

I am playing with infill prints which may be another option to create my mesh walkways but still would like to be able to get reliable prints even at the small scale I am working at. 

RE: Can you force printer to avoid turns during print?

Posted by: @mac-phd

Thanks everyone for your help so far.

I have been a bit slow posting in this thread since my printer was giving me far bigger problems with a y-shift that was messing up all my prints. Turns out the little screw that holds the gear tight to motor was loose...

Fixed that but now I am back to the original problem -- the horizontal / shorter lines are either being printed incomplete or coming out somewhat diagonal if I put interconnecting elements to force the printer to follow a path. I tried slowing down the printer and this did not eliminate the problem (I cannot tell if it even helped).

I am playing with infill prints which may be another option to create my mesh walkways but still would like to be able to get reliable prints even at the small scale I am working at. 

There are two of those screws, and both need to be tightened properly and in order.

Flat First: Drive gears must be tightened flat-first.

1)   Start with both set screws fully loosened so the pulley is free to spin on the motor shaft.

2)   Align one set screw dead center with the flat on the motor shaft, slowly tighten the screw until it fully contacts the flat surface.

3)   Torque the flat set screw to spec.

4)   Now tighten the jam set screw, and torque it to spec.

Once tightened, never touch the flat set screw unless the jam screw is first fully loosened.

Why Flat First? Set screws have flat ends. If you tighten the jam screw first the set screw on the shaft flat doesn't fully contact the shaft, only one small edge of the screw surface is biting. Reversing torques can easily shift the shaft to a position the flat screw no longer contacts the shaft. This lets the jam screw wriggle loose. And after a while, vibration loosens the screws until the gear is free to rotate.

RE: Can you force printer to avoid turns during print?

As for getting patterns with infill: set top and bottom layers to zero (as Neo siad); and adjust infill percentage to get the approximate size of pattern you are looking for.  You can try grid, rectilinear, hex, or even star or cubic and 3d patterns.  Each has a benefit and is useful for controlling final look.

Loose or improperly attached drive gears cause all sorts of printing problems - and may still be something you are fighting.  Tighten both X and Y belt drive gears following my post above then report back. It might help with the poor print performance.  And yes, gears can wiggle on the shaft and you can't see it, but it does affect the print.

Here's my grid setup ...

Grid_Block

RE: Can you force printer to avoid turns during print?

Played with a few infill settings and these are great -- much stronger than the layers I was printing and was able to get to a setting that works well for the walkways I need to create... Picture attached (I decided to do diagonal infill since I could not guarantee even spacing when I made the pattern 0/90 degrees to print. Thank you @tim-m30 -- I never would have thought of doing infill like this to get the result I needed.

Wish there was a way to manually encourage the software to print paths with square corners and extra crossing of paths the way it does in infill mode.