Print breaks while removing support
A couple of days ago I revers engineered a blender coupler for a coleague of mine.
This was the result
Overall dimension are perfect, the worn part of his coupler was reproduced well and accepts the blade shaft nicely, but the problem is removing the supports.
The overall dimensions are 35 mm widest diameter (above the fins) and 23 mm total height.
The critical part are the fins. They are fileted at the bottom and they are 8,5 mm long, 8 mm high and only 1,5 mm wide. While removing support I broke 7 out of 9. Most (5) broke off while I removed the top horizontal support and the vertical supports next to the fins deformed and took the fins with them.
That is my main problem. The second one is the hole in the middle. It gets filled with support which I can't get out.
So I need a lot of help with this, if possible. I've used Cura to generate my G code. Surfaces are smooth, I'm printing 0,15 mm layers with 0,2 initial layer. But I've left the support Z distance at 0,1 mm and X/Y were at 0,2. This is obviously too small of a clearance. I need the support to snap off easily, because of the fragile fins and the middle hole.
There is another, bigger hole on the upper side of this coupler and that one doesn't connect to the hole you see in the image. If all else fails, I can connect the holes so I don't need the support inside, but the fins are still a problem.
I could increase the Z and X/Y distances, I don't need the bottom surface to be extremely smooth, but since the fins will forbid more surface finishin, like sanding or something else, I want to get as smooth of a finish as I can with the supports.
So any suggestions on the distances? Would 0,5 for X/Y and 0,3 for Z be OK?
Also, I barely managed to remove the print from the bed. I left it to cool for 1,5 hour and I couldn't lift it with a spatula. I had to twist it from the bed. Luckily, the PEI didn't brake with it, but I'm not too sure how far from ripping it off I was. So some help with that would be nice too.
Re: Print breaks while removing support
Turn it over it will take more support. but be much easier to remove the support
if you can continue the hole through the model it will make removing the support from the hole, easier.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Print breaks while removing support
if that was me, i would model some sacrificial 1 wall thickneess circles on the shaft side, reducing in size to the middle, print it blades up and cut away the rings manually after
Re: Print breaks while removing support
If it was me doing this, I would not.
I really don't think that this model will be able to be printed and then work without delaminating; there simply is not sufficient strength in printed parts to stand up to being spun at speed. At least, not in the possible print orientation. Acetone-smoothed ABS would maybe stand a chance, but I would not take the risk.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Print breaks while removing support
I don't have ABS filament at the moment, I'm printing this out of PLA, if it breaks in use, no problem, it's a small chinese made blender, they can't get spare parts for it so they will have to buy a new one anyway.
But I'm not sure it would delaminate? I mean, there is minimal stress in Z axis with this orientation. And it's not a very powerful motor.
Anyway, I'll print this the other side down so I don't have supports around the fins (this actually came to mind after posting the question). But the question still is, since this is my first supported print, what are some good rule of thumb settings for support distances?
Re: Print breaks while removing support
XY gap should be around 0.5mm, Z gap 0.15mm and inflate support by 0.5mm.
I have found those to work OK.
Regarding the model, if an injection molded (presumably) ABS part can break, then PLA will delaminate unless you have the lines printed vertically (or print the part on its side - not really feasible). There there is also the question of infill and balancing...
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Print breaks while removing support
What do you mean by inflate support?
The injection molded part is true, but it didn't break, it wore out. And if I did my measuring right, the design was at fault here. On the upper part of the coupler, there is a 9,5 mm hole (dia.) which is also 9,5 mm deep. This hole recieves the blades' shaft, which is 5,5 mm in diameter and has two flaps where it connects to the coupler.
These flaps are 1,5 mm thick,they are arched and the total horizontal length on the flaps is 8 mm. Now the problem is that inside the hole, there are 4 cuboids that are molded onto the inner hole diameter. They were 5,5 mm wide. I did some quick calculations on this and if they were 5,5 wide, and the flaps are 1,5 wide and need to fit into the corners, that means that each cuboid would have vertical height of around 0,5 mm where it intersects the inner hole circle
Anyway, that means that only one of the flaps on the blade's shaft would be cought by the cuboids on the coupler, and if the shaft was centered, the cuboids would be worn out (this is precisely what happened, the wear on the coupling is perfectly round, so the shaft ate into the coupler whenever it managed to catch it. This was obviously designed to fail, and since there are no spare parts, you have to buy a new blender.
I've made the cuboids 4,5 wide, but that increased their height to 1 mm. This way, I believe that the shaft-coupling fit would be a lot tighter and when in position, the flaps won't be able to exit the corners (where there's now 1,6 mm distance between corners).
In any way, this desing should reduce wear on the coupler. Will it delaminate, possibly, but we'll give it a try just for the fun at least.
Re: Print breaks while removing support
Inflate support. Sorry this is a KISS setting; I don't know if it is available in Slic3r, but what it does is to inflate the support and its bed interface beyond the perimeter of the model by the specified amount. A very useful option.
Certainly it will make a good test print, even if it may not work in practice. Your idea about getting a better fit makes total sense.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Print breaks while removing support
Slic3r does this automatically on stock settings, although I'm not sure what it's called either 🙂