ABS or 30% Glass Filled Nylon feature size

[martin05]

I'm working on a design that requires a ratcheting mechanism to be molded into the parts.

Two parts slide with respect to each other. Each of the parts would have triangular teeth molded on facing surfaces. The parts would click one step at a time as they are slid with respect to each other.

The ratchet is also one way. You can slide (click-click-click) one way but have to press a button to disengage the teeth to be able to slide them the other way.

I would like to make the steps as small as possible. I find myself wondering about what the minimum reasonable feature size might be from a moldability standpoint for something like this. Right now I have them specified as right triangles 0.050in by 0.050in. The pitch or step is also 0.050in.

Strength isn't a huge issue as the assembly probably won't see more than about 5.0lbs applied to the teeth. The ratchet will have about six teeth engaged at all times.

Are there any issues to consider if one were to use ABS vs. 30% GFN.

Any recommendations on a forum that might be more intensely dedicated to plastics engineering and design issues such as this one?

Thanks.

 

[patprimmer]

Like Mike says, 3D printing does not have the fine resolution for the detail in the teeth. Due to laack of pack and due to small notches it also does not develop full mechanical properties and will not be available in some of the resins that might prove best for this.

An epoxy mould in a bolster might make a better prototype or a simple aluminium mould with no cooling ejection etc to just get a few shots out at minimal costs.

Regards
Pat
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