<p>It is not possible to insert a steel dowel into a hole of a plastic workpiece with a press fit: at least not for long. Tremendous force is exerted on the plastic by the steel, and the plastic will soon begin to deform in a process called cold flow or creep.</p>

CC BY-SA 4.0
2023-02-06T08:04:02.313Z
Thanks for posting your own answer. I've done this multiple times, I guess is depends on the application. The HyperCube Evolution CoreXY printer uses such pins to mount the nozzle assembly to the XY carriage (I've used Nylon for that), and the SMuFF multi color extruder uses the same principle to connect all the extruder bodies. Never seen any problems with this.
0scar
CC BY-SA 4.0
2023-02-06T13:04:46.140Z
Maybe you have a magic plastic. Or maybe the interference fit exerts little force, or maybe not enough time has passed for effects of creep to appear. I don't know. The fact of the matter is that plastic deforms over time under constant load.
adamcircle
CC BY-SA 4.0
2023-02-06T13:07:44.333Z
The question doesn't explain that the pin is loaded or how for that matter. Maybe you should add that in the question.
0scar
CC BY-SA 4.0
2023-02-11T23:27:33.123Z
Whether creep happens, and the extent to which it happens, varies by material. Nylon is particularly bad for creep. So is PLA. ASA and PET (and possibly PC?) however seem to have minimal or no creep.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2023-02-06T01:56:39.260Z
2023-02-06T13:01:16.160Z
2023-02-06T13:01:16.160Z
adamcircle
<p>I'm building a product which requires a dowel pin inserted into a plastic piece. I'm planning to 3D print the plastic piece with nylon (must be nylon for biocompatibility), but the tolerances won't be sufficient to ensure a consistent press-fit for the pin. To get around this, I plan to undersize the hole, and then ream it out with a reamer on the drill press. There will be 1000 pieces on this run. Any flaws you can see with this design?</p>

CC BY-SA 4.0
2023-01-30T21:53:14.317Z
Give us more details. What are you building? What is it for? Dowel pin out of wood or metal?
AzulShiva
<3d-design>
Inserting steel dowel pin into hole with interference fit
adamcircle
# Inserting steel dowel pin into hole with interference fit

(Asked by: username_0 on 2023-01-20)

I'm building a product which requires a dowel pin inserted into a plastic piece. I'm planning to 3D print the plastic piece with nylon (must be nylon for biocompatibility), but the tolerances won't be sufficient to ensure a consistent press-fit for the pin. To get around this, I plan to undersize the hole, and then ream it out with a reamer on the drill press. There will be 1000 pieces on this run. Any flaws you can see with this design?

**Tags:** 3d-design

> **Comments:**
> **username_1**: Give us more details. What are you building? What is it for? Dowel pin out of wood or metal?  

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## 1 answers

### Answer by username_0 on 2023-02-06. Score: 1 | Accepted answer

It is not possible to insert a steel dowel into a hole of a plastic workpiece with a press fit: at least not for long. Tremendous force is exerted on the plastic by the steel, and the plastic will soon begin to deform in a process called cold flow or creep.

> **Comments:**
> **username_2**: Thanks for posting your own answer. I've done this multiple times, I guess is depends on the application. The HyperCube Evolution CoreXY printer uses such pins to mount the nozzle assembly to the XY carriage (I've used Nylon for that), and the SMuFF multi color extruder uses the same principle to connect all the extruder bodies. Never seen any problems with this.  
> **username_0**: Maybe you have a magic plastic. Or maybe the interference fit exerts little force, or maybe not enough time has passed for effects of creep to appear. I don't know. The fact of the matter is that plastic deforms over time under constant load.  
> **username_2**: The question doesn't explain that the pin is loaded or how for that matter. Maybe you should add that in the question.  
> **username_3**: Whether creep happens, and the extent to which it happens, varies by material. Nylon is particularly bad for creep. So is PLA. ASA and PET (and possibly PC?) however seem to have minimal or no creep.  

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