Hello,
I have been having an issue with Fusion 360 and 3D Printing my designs. I am certain that the issue I'm about to discuss is of my own making but I need some assistance in discovering what I'm doing or thinking that's causing my problem. If I have posted this in the wrong location, please forgive me and move it to wherever it is the most appropriate.
I don't know how to state my problem succinctly but it has to do with extrusions and the way they turn out on my 3D printer. I also don't know if it happens all the time with every extrusion or with just some extrusions, but when it does occur, the parts that get 3D printed are very weak along the boundaries of the extrusion. I have had this problem a number of times and I'm confused as to what is happening to cause the problem.
Example 1:
I will begin with a simple example to start off the post but this isn't the example I will be describing in more detail later on. I apologize that I don't have pictures of this one to show but hopefully the description will suffice, and perhaps more particularly when viewed in conjunction with the next example that I will provide several pictures.
I recently made a simple box shell in fusion 360. The top was open but that's mostly an irrelevant detail I think. On the back of the box, from the original sketch, I made four "standoffs" using extrusions from circles in order be able to have it mount to a plate that already has some bolts (bolt heads) in it that I wanted to clear. The "thickness" of the standoffs were 4 mm, so pretty thick. The thickness of the back plate was 2 mm, so also fairly thick. The box is for a model and is attached with screws to the aluminum plate. The plate was threaded for the screws.
Everything came off of the 3D printer seemingly in perfect shape. The box was well-formed, the thickness of the floor was right at 2mm, the holes for the screws were right at 5 mm and the standoff around the outside was right at 4mm. All as designed within a small variance. When I went to mount the box to the plate all of the holes lined up perfectly between the box and the plate. There was no twisting or bending involved in any way. But as I was tightening down the screws, they ripped the standoffs right off of the box as if they were nothing.
In examining the box where the standoffs had been, there was hardly any damage. It was as if they were hanging on by a thread to begin with and not integral to the structure of the box, which they should have been by 2 mm's worth of thickness along the structure of the box itself, and 4 mm's in diameter around the screw hole. And yet they tore off like they were simply paper.
Example 2:
Fusion 360 Part for examination: Deflector Plate
For my second example, this is a part I have been working on for a while and have gone through several iterations of it with each getting successively weaker in the areas between the extrusions. Which is pretty much the same problem I had with the box model in the previous example. The most recent version I printed out was so fragile it broke apart very shortly after I pulled it off of the 3D printer, just by handling it.
As you can see in the pictures below, rather than being solid models, they just fall apart at the extrusions.
In my sketches, all I'm doing is creating the various circles and whatnot and then highlighting what I need to extrude and entering the thickness. When I look at the part in Fusion 360 I don't see any problems with it. It is only when I download it and slice it up (and I've used several different slicers) and then print it out that I have problems.
I have other examples of other models that I've made that have this problem. When I examine the part it always comes back to problems around the extrusions. I do not have this problem with other parts that I download and print. Only the things that I design myself.
Can anybody help me understand what I'm doing wrong??
Thanks,
John
Here are some pictures which illustrate the problem:
