Hey everyone, I’m working on a school project designing a component for our team sail boat and am asking for some input on the design of a screw section:
o Lead screw is used to compress compression spring only
o Axial force requirement not yet calculated but will be very low and in 1 direction only (reaction force of compression spring)
o User rotates lead nut to create axial movement in lead screw and compression spring used to return lead screw to home position
o Will be a high-helix multi-start thread
o High helix: lead must be ~60mm (2.36")
o Multi-start: 8 start looks the part but this is not following standard for root/crest width. Standard would result in 12 start but since this is low axial load I will opt for lower count
o Size: external thread major diameter = ~33mm (1.30")
o Spatial: thread depth must be as shallow as possible due to need for large lead screw shaft hole diameter and radial clearance limitations. This will likely require us to have a thread depth shallower than standard.
o Buttress vs stub ACME for high-helix (60mm) multi-start (12) threads:
Is this possible for both thread styles?
Which is better suited?
Which is easier to manufacture with these constraints?
o Buttress vs ACME for shallow tooth height:
Design standards have tooth height at 0.3P for stub ACME and 0.66P for Buttress, but for our constraints (1 direction load) shouldn’t a buttress thread with a tooth height of 0.3P be stronger than a stub ACME if axial load is the same between them?
Any help is much appreciated, thank you very much!
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