I'm planning to print a certain sample holder which is going to be placed on a CD-Rom BLDC motor and spun at about 1000-1500 RPM. The holder would essentially be a 2-3 mm thick 100 mm square platform with 1-2 mm thick hooks rising up from outer edges of the platform to hold the sample. The bottom of this platform would also contain a 15 mm diameter crevice designed to latch onto the disc holder attached to the motor. How durable would this printed holder be under these conditions, if it was made of ABS plastic, for example?
Asked
Active
Viewed 472 times
6
-
Please consider to add specific details to your query. You likely would be able to spin even PLA at those speeds if the sample item was fairly small in diameter, while it can be expected that ABS would fracture if the sample part is 200 mm in diameter and 2 mm thick. Please also consider to reference item shape, thickness and direction of print layers. As Johnny Five would say, "Need more input!" – fred_dot_u Sep 20 '16 at 20:58
-
The part would essentially be a 2-3 mm thick 100 mm square platform with 1-2 mm thick hooks rising up from outer edges of the platform to hold the sample. The bottom of this platform would also contain a 15 mm diameter crevice designed to latch onto the disc holder attached to the motor. – Osta Sep 20 '16 at 21:46
-
@Osta: I suggest you update your question with this information, so users don't have to scan the comments in order to get the relevant information. – Dampmaskin Sep 21 '16 at 09:06
-
Is your sample going to be contained within the perimeter of the hooks, or will the hooks be used to secure the sample as it whirls about the outside of the manufactured part? If the sample is contained within the perimeter of the hooks, is it of uniform or symmetrical shape? That is, will it balance about the center point? – fred_dot_u Sep 21 '16 at 20:46
-
The hooks would be used to press the sample to the platform. The sample itself should cover most of the area of the platform and retain the center of mass of the whole structure near the rotational axis. – Osta Sep 22 '16 at 20:18
-
If the sample covers the platform, does that mean there is a hole in the approximate center or that the platform has a recess to prevent the need for holes in the sample? The selected answer suggests printing hooks in profile, but that's virtually impossible if you have more than four hooks. Consider, however, a raised ring at the perimeter, which will provide retention and a bit of designed-in strength. Reinforcing the platform with light weight fiberglass cloth and epoxy resin will also add strength (and weight) and may require a different choice of motor. – fred_dot_u Sep 23 '16 at 17:56
-
I hope this is for a temporary prototype. Over time ABS absorbs water in the air and becomes brittle (it maintains its strength for longer in air-conditioning of course). Noticed it on my laser printer chassis, give it 12 years or so i guess. – digitallyhere Oct 11 '16 at 10:57
1 Answers
3
Really the only thing that would matter for this project is the amount of torque the motor has available and subsequently how heavy your setup is that is connected to the motor. A part that size may just be too heavy for a CD-ROM motor if you intend on adding more parts.
However, to answer your question, ABS should be able to endure the stress. I recommend paying attention to how the hooks are printed. You'll want to make sure that the hooks are printed in profile, meaning that the profile of the hooks should be printed with each layer. This will help provide structural integrity to, what sounds like, the most stressful area of the part (the outer edges of a spinning device and a clamping feature).
Something to keep in mind for projects like this is that most of the time the design will likely be the cause of failure, not the capabilities of the material.
-
Printing the hooks in profile results in layer structures that are weak across the surface of the holding design. A hook of 2mm height will have very little general structural strength, regardless of print orientation. Of course, ABS will be stronger than PLA, but I suspect that some additional reinforcement will be necessary. Subsequently, additional weight will be added. – fred_dot_u Sep 23 '16 at 17:54
-
@fred_dot_u I think this highly depends on the actual design of the hooks. In the end, if the design is flawed, the part will break and OP will have to adjust and re-print. That's the beauty of 3D printing, it's a low-cost prototyping machine. – tbm0115 Sep 26 '16 at 14:14
-
2 mm height does not leave much with which to work. Aluminum or other metal might be okay with such a small or low profile, and injection molded plastic or similar near-monolithic construction might be okay, but as strong as ABS plastic can be, it's formed in layers of reduced strength. It would be interesting to have an engineer provide the real world figures of such a model spinning at the speeds noted. – fred_dot_u Sep 26 '16 at 15:07