Printed sizes not as expected

[cncpadawan]

Hello!

I am new to Simplify3D, so I am still learning as I go. I have a model I am trying to print that I designed in Fusion 360, and it seems I am having some problems accurately printing it when exporting it to Simplify3D.

There is a slot in it, about 8.1" x .45" and every time I print using Simplify3D, the slot ends up being .03 or more off with the short dimension. Long dimension is short too.

Here is the strange part... using Makerbot Desktop, I was still off, but I was closer to the size it should be. Long dimension was fine, but short was off by about .01"-.02".

The object stretches my machine to the limit... the bed is 8.8" roughly and what I am printing comes out to be about 8.5". First time I printed, I left the skirt on not realizing it wouldn't error or anything.. it printed, but it automatically scaled it. I am wondering if that is still happening even though I disabled the skirt, but I have no way to verify this since I can't seem to find a way to get dimensions other than what it says the object dimensions are in the model (which, when converted from mm to inch, are spot on).

Is there a way to determine if it is still scaling the model down, or is there a way to prevent it from doing so? I don't think the printer is the issue.. I printed other items that fit well on my bed and they appear to be just fine (printer is a Wanhao Duplicator 4, I printed mounts for side plexiglass and they printed just fine, sliced with Simplify3D).

Just not sure where to start with this problem. I am printing a size gauge right now.. varying slots in the 8"x.45" range to see how much things change, and if it still does not come out right, I'll print with Makerbot Desktop to see if there is a difference, but hoping someone knows some secret setting in Simplify3D that I am missing.

I have attached the factory file for the gauge (which I am still trying to figure out... it seems to keep opening the same factory file over and over, it would be nice if the processes could be saved but it opened a new factory file every time.. maybe I am just not used to the workflow yet).

Thanks!

[JoeJ]

It isn't going to scale your model unless you tell it to. If you're off by 0.5mm, then you're probably either under or over extruding. I would start by making sure that your extrusion multiplier is definitely correct.

If you are certain the extrusion multiplier is right, but the parts are still slightly off, they have a great feature that allows you to account for this. Read more about it here: http://forum.simplify3d.com/viewtopic.php?f=8&t=2042

[cncpadawan]

Hello,

Thanks for your reply!

On the scaling, all I know is that with the skirt off the print spans across more of the build plate than with them on, and I posted on a Facebook forum and someone else had the same problem I did in that case. It's strange... but I have 2 pieces, one larger than the other to prove that 'something' happened there, even though they came from the same model.

My print last night shows that on the narrow side, it is .06" too small. Length-wise, it is also too short based on what the CAD drawing has, and what the software states it should be (my caliper doesn't measure that long).

I will take a look at that feature and see if that will work for me, thank you! I am going to try the same design with Makerbot Desktop again and see if I get a different result too, to try to determine if it is something strange I am running into my machine or something else.

How do I verify what my extrusion multiplier should be? I am using the profile for my printer that is in the software, so not sure where I would find that information. Makerbot Desktop just worked, so I didn't have to mess with these settings.

Thanks!

[cncpadawan]

Hello,

These are the results of my experiment and what I have done.

I upgraded my printer to Sailfish 7.7 following directions and changing settings based on other Wanhao users. Everything went fine there.

I then designed a cube that is 1" and hollowed it with an open top, making the walls of the box to be 1mm in thickness. Figured that way I have plenty of measurements to examine.

I sliced this design using Makerbot Desktop and Simplify3D. For Simplify3D I used the Replicator settings instead of the Wanhao Duplicator 4 settings as someone else had suggested doing so, and had to correct the bed size again. I then printed both of these test cubes, and ended up with the following measurements:

Makerbot Slice: .9955" x .987" x .9925" Z with 1.06mm walls
Simplify3D Slice: .9375" x .9275"x .9925" Z with .87mm walls

It appears there is some adjustment to be made (not sure what, or where, exactly since I have never had to worry about it thus far with my printing) but Simplify3D is significantly off. With my other prints, it seems to be at least .06" (about 1.5mm) off and that seems to be reflected still. It also seems the wall thickness is too narrow.

This being the case, I am guessing the changes I need to make are going to be in Simplify3D, but not sure what changes to make and where to make them. Any suggestions would be greatly appreciated! I would like to make use of this software I just bought as it looks like it is a good and plenty of options, just not sure where to begin!

Thanks!

[cncpadawan]

I've been thinking about the horizontal size compensation functionality, and I don't see that as being viable in this situation. It seems, from what I read, that it will either grow or shrink what is printed, but I need both, in a way. The slots are too narrow, so if I shrink them, it also shrinks the entire piece which is too small to begin with. If I grow the piece, then the slots become more narrow.

[jimc]

You need to run a thin wall calibration print, like you did, and adjust the extrusion multiplier until its all in spec. This will increase or decrease the amt of extruded plastic. You need to get the actual printed wall width to match the extrusion width you have set in the software. Before you mess with the multiplier measure your filament and set that correctly in your settings.

[cncpadawan]

Hello,

Thanks for the suggestion, I will give that a shot. Didn't see your reply until now, but in the meantime I did more testing per some suggestions I received from the business I purchased my unit from.. giving it a shot in ReplicatorG. So I did.. and also tried the FlashForge Creator Pro profile the folks at S3D suggested I try to fix the size of the print bed. These are the results:

RepG - 1.004" x 1.004" x .981" with walls of 1.18mm
FF S3D Profile - .994" x .981" x .991" with walls of .89mm

So just to clarify.. the software is set to have an extrusion width of .40mm. I need to change my model to that target, then adjust the extrusion multiplier to match that? I also read somewhere to set the width to auto... I am assuming it is safe to do once I have everything else dialed in?

[JoeJ]

You need to fix your extrusion multiplier. Take a 20mm cube and print it with only 1 perimeter outline, 0% infill, and no top solid layers. This way you can measure the thickness of your single perimeter wall. If you set the software to have a manual extrusion width of 0.4mm, you still need to adjust your extrusion multiplier to make sure that this is the case. So print that single perimeter cube, and adjust the extrusion multiplier until the wall measures 0.4mm thick.

[cncpadawan]

Ok.. I will give that a shot tonight if I can. I did manage to get fairly close last night, changing the multiplier with my cube that I put together. I printed a piece with slots of different sizes and it seems that most of them are within .01" now. I will see if I can't fine tune it using this process, thank you!

[JFettig]

This is really interesting, I've been struggling to print stuff to proper size on my delta and I've skewed the calibration so far that its totally unreal just to get it to print closer.

I'm going to have to print some of the same stuff with different slicers to see if I get different results.