Threaded Fasteners
 Download spec sheet
Fastening your Prototypes Together
Often times your project involves mating parts, that will be screwed together using one of several types of fasteners. At Protogenic, we’re very familiar with several options, and are ready to work with you on a solution that works best for your design. Try to avoid using self-tapping screws with prototypes, since the materials will tend to split or crack under the pressure of the screw. Instead, opt for one of these approaches…
Tapped Holes
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Good for:
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Nylon, SLA’s, especially durable & water clear resins
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Not recommended for
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Cast urethanes, rigid SLA resins, PolyJet
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Notes:
Drilling and tapping is a good solution when you have very thin boss walls, you don’t need the threads to withstand several assembly cycles, or you don’t want a threaded fastener visible in your model. Talk to your project manager or a member of our sales team to discuss if drilling and tapping is the best solution for your application. Also, just core the ID of the hole to be tapped to the tap drill size for the threads you want, let us know what holes are to be tapped and we’ll take care of the rest.
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Threaded Inserts
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Good for:
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SLA’s, all types. Also ideal for through holes where access to back side is available, and shallow blind holes.
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Not recommended for
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Soft urethanes, high pull force applications
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Notes:
We have many brass threaded inserts on hand, in most common sizes when your design calls for press-in threaded fasteners. This is a good solution for most boss designs, or threaded holes in solid floors, particularly when used in a shallow blind hole. We use a .002” interference fit, and also bond the inserts in place as they are pressed in. Inserts are a good solution when you plan on using the threads more than a couple of times, during several assembly cycles. We also provide the correct boss sizing for all the inserts we stock on our Threaded Fastener Specs page, you can download the .pdf here. For through holes, consider using a headed insert, with the flanged head on the opposite wall from the pulling force, for a very strong hold.
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Threaded Helicoils
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Good for:
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SLA’s, especially durable & water clear resins. Cast urethanes, deeper blind holes.
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Not recommended for:
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Rigid SLA resins, soft cast urethanes, extremely thin boss walls or shallow blind holes
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Notes:
Helicoils are an even more robust approach to threaded fasteners, compared to threaded inserts, as their engagement with the SLA or urethane is greater than a mere interference fit. Helicoils are ideal for multiple assembly cycles, and when a greater pull strength is required of your prototypes. Because a drilling and tapping step is required prior to assembly, a deeper hole or through hole is required for Helicoils. As with threaded inserts, refer to the .pdf of the Threaded Fastener Specs page for proper boss sizing.
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In general, using one of these three techniques for adding threads to your prototypes will make them look better, last longer, and most importantly, function better than if you were to rely on press fits or self tapping screws. Be sure to ask your project manager or a member of our sales staff if you have any question about which method is right for you.
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