Whats the best pattern / or even shape for this part?
Hi All,
i need to print a "foot" for a box (the box will stand on 4 of these). The foot is height adjustable and will be fastened with a larger "Thumb screw". So there will be signifant pressure on the part (on the flat side). The part fill be guided on both sides so it can not rotate.
As it's going to be relatively big ~20cm long I'm wondering that the most efficient, yet stable way to print is. Especially given the pressure de to the screw.
How would you do it (infill %/pattern, walls,... ) / or even optimize the shape?
Best
Dennis
RE: Whats the best pattern / or even shape for this part?
Replying for the update.
RE: Whats the best pattern / or even shape for this part?
Good morning Dennis,
there probably isn't a 'Correct' answer to this question
anyone responding will probably have a different set of personal preferences which they will apply to the query.
Here's my take on the subject
we have no indication of the final loading in any direction except that there will be significant clamping force where the fixing 'Larger Thumb Screw' contacts the leg
I Would suggest that you use a large 'penny round' washer between the thumb screw and the leg, in order to spread the clamping force over a larger area, with perhaps a thin rubber washer to provide additional friction and load spreading between the penny round washer and the leg.
I would consider modifying the leg as shown below, and (assuming a 0.4mm nozzle (A larger nozzle would print faster and there are no intricate details to deform))
I would use enough perimeters to fill the space either side of the central slot (In this example I used 25 perimeters)
this will leave a 'delta section' towards the tip of the leg with less 'structure' in this area I would suggest Gyroid infill, as a 3 dimensional infill.
additionally I would consider making the lower contact area less rounded, to reduce point loading on the surface below, and to increase the contact area for reduced wearing. I would round the ends on the central slot to remove potential stress risers at the corners of the slot, and I would put a small chamfer on the corners of the model to remove sharp corners which would be more likely to get damaged, or cause damage to other items
the thickness of the top of the leg is quite small, I would consider making the slot shorter to make the top of the leg stronger when clamped at full extension,
lots of perimeters can look a bit ugly from the outside, so I have set the top and bottom layers to show only one perimeter, this will not significantly affect the strength of the leg,
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
@joantabb is right but I would add one precaution:
IF this part is to be under continuous stress don't use PLA, it (very slowly) evades stress. However, PETG should be OK.
Cheerio,
RE: Whats the best pattern / or even shape for this part?
Without a sense of total load, hard to say what material and what settings might be "best". But in general, I concur with Joan. More perimeters are usually better than more infill. You'd probably be finer with fewer perimeters and 40% or so cubic infill. Rounding things out as she suggested makes sense. Not sure why this model needs the "toe", is there a functional reason for it or just aesthetics? I would make the whole thing symmetrical. I would probably print it in ASA but PETG or PLA might work just fine.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Whats the best pattern / or even shape for this part?
THanks a lot for your answers. To answer your question:
- The load per leg will be max 5kg, probably less
- I planned to use PETG
- The Toe is kind of aesthetics 🙂
RE: Whats the best pattern / or even shape for this part?
I updated the model a bit. Thanks @JoanTabb.
Parimters are set to 20 and I choose 40% cubic infill. This is how it looks:
RE: Whats the best pattern / or even shape for this part?
Good luck,
PLA is probably not ideal. ASA, ABS, PC, all more robust than PETG
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: Whats the best pattern / or even shape for this part?
Thanks a lot @everyone
RE:
What I'm wondering about is why there wasn't any talk about how much top/bottom layers there needed to be.
If I interpret the intended use of the part correctly, if the 'box' stands on these 4 legs and something bumps into that box, the feet can get significant sideways forces. So I wouldn't skimp on top and bottom layers. Say 10 or so.
My gut feeling says that 15% infill or so is enough and I would go for a cubic. Because I like triangles - strengthwise.
I often use modifiers to increase perimeters and/or infill and/or top/bottom layers at the critical sections. So I did that and reduced the number of perimeters to 6 which seems like more than enough for me, since the critical part is now stronger.
How I would print it is in the attached 3mf.