How bad will this tall skinny part fail.... Before i print

[Raddiver]

I have a cylinder that is 6mm in diameter with threads at the bottom and is 170mm tall.
is this going to be a difficult print, easy peasy, or somewhere in between?

-Rad

[Tim]

Well, if you print it vertically, it's almost certain to fall over unless you have a pretty wide brim at the bottom to keep it stable.

It depends on the filament type that you're printing it with, but it should probably not have any issues printing. If you print with PLA anything that is that thin and printed vertically will be very weak along the layer lines. So how much stress the part will be under should be an important consideration.

If it is at all feasible to do it, cut the model in half lengthwise and print it flat in two parts and glue them together.

[willnewton]

Mmmmm.....
Good luck with that.


Seriously though, it's probably going to fail from wobbling during the printing. The print head will have a lot of leverage once it gets tall and likely knock it over. You could add some easy to snap off supports or print multiple objects with a very light bracing between them all.

Maybe you can print it laying down?

You could just try adding a wide brim (5-10mm) that is a layer or two tall and see if it works to stabilize the print as well.

-Tim posted while I was typing, so some repetition here

[Jules]

It's gonna be a challenge, and it's gonna depend on what you are printing it out of.

ABS: Nope. Gonna crack, split and warp.
PLA + : Possibly. Print it VERY slowly, with a slight jump on retraction between layers, and a HUGE honking brim over heavy adhesive to stabilize it, in the low to medium temp range. Hit the print with extra heavy cooling.
PETG: Possibly. That one is much stickier and doesn't warp, and has to be printed slowly, but if you have it dialed in, it will work.

The picture below shows what happens when you print a 0.73 (average) mm diameter column out of PLA at super slow speeds. Look at the size of the brim on it in relation to the center column. That print got up to 120 mm tall before I killed it. At the lower levels, you're fine, but vibrations from the machine moving cause a wiggle to develop, the higher up you go with the print.

(If you want to keep that from happening, I'd design some removable buttresses to keep the center core stable.)

[Jules]

Well, if you print it vertically, it's almost certain to fall over unless you have a pretty wide brim at the bottom to keep it stable.

It depends on the filament type that you're printing it with, but it should probably not have any issues printing. If you print with PLA anything that is that thin and printed vertically will be very weak along the layer lines. So how much stress the part will be under should be an important consideration.

If it is at all feasible to do it, cut the model in half lengthwise and print it flat in two parts and glue them together.

Oh yeah, totally didn't think about the stress aspect. Tim's right, you probably would be better off splitting it, printing it horizontally, and gluing it together.
(Going to save you hours of print time doing it that way too.)

[Raddiver]

Thanks all,
I'm printing with ABS.
It's a rod for a slatwall hook that im designing. Most of the products i will be hanging on it are light. In total, maybe 6-8 ounces once loaded up.

I decided to go ahead and make this a learning experience. Im going to do a couple of prints at various speeds to see at what height they fail, But i'm sure ill go to the split and glue method.

In terms of gluing, is super glue ok, or is there some super secret maker glue i need?

Thanks for the advice.
-Rad

[Raddiver]

Ok, so i had a forced break-time.
While on this break, i started thinking about slowing the print down as per jules recommendation. What about the relationship of speed to extruder temp?
I'm assuming that the temp should really be dropped because the filament is being extruded slower, I.E more time in the nozzle getting up to temp.
Is there a good rule of thumb or formula to use in determining this? or do i need to wing it?

As far as the print itself goes. It actually stayed in place through the whole print. Printed well for the first 51mm. Beyond that, warping ensued. Not unusable, but not pretty either.

[Jules]

Actually it's exactly the opposite for ABS - don't speed it up, but try to keep it warm while it prints. If you can rig some sort of cover for the machine - it will improve the warping problem.

Or try PETG....it doesn't warp. Or split. Or shrink. Very strong. (Really a great filament.) Got to be printed at a snail's pace.

[Matt_Sharkey]

If this is a "rod" for a slatwall, does it need to be perfectly round? maybe a square tube would work just as well?

This is the point where you need to consider the limitations of the machine when designing for a specific purpose.

[jsc]

It's tempting to want to print everything, but when it comes to things like long thin rods it's sometimes better to consider if maybe you can design parts around stuff you have on hand that's better suited for the purpose. I bought a few dowels of various diameters at a craft store a while ago for a few bucks, and saw off a bit whenever I need a roddy thing. You can build all kinds of fun things with dowels and printed connectors.