I've been printing some gears using ASA plastic, they work really well but under high loads they loose a lot of torque, looking through the gear ratio I from the motor (the torque of which I know at any given current) I find that after speed reduction, and supposed torque increase, I'm only getting 25% of my expected torque. My gears are proper involutes, so there isn't a design problem here, and they turn fine at low loads. They don't backlash much either. I think that the plastic might be causing firction though, especially where the teeth mesh (there is afterall a rubbing component of force in gear meshing for any pair with a non-zero pressure angle). Can anyone recommend lubricants good for use on ASA, ABS and PLA plastic? Ideally something I could almost "paint" on and never need to replenish over time (so not an oil which would drip off). The lubricant would also need to be non-condutive (incase any gets splashed on to nearby circuitry), and hopefully not too messy in general, not something which will get flicked all around the nearby motor, circuitry, battery compartment, sensors, switch contacts... when the (largely not enclosed) gear system runs.
Thanks
Loosing torque at high loads means friction. That is likely due to the shape of each tooth is not correct and the teeth are sliding rather than rotating as the mesh and disconnect.
Paul
The teeth are involute curves with a 20 degree pressure angle, generated by a script which seems reliable(the script also tells one exactly where the relative axes of both gears in a pair sit and so on). My problem isn't gear shape, it is the friction of the plastic itself. can you recommend a lubricant to aid with this?
Any general purpose lubrication grease (that thick stuff) will do. Graphite spray will work, too. Please note: WD40 is no lubrication grease, it's a solvent.
Any plastic with a styrene component like ABS, ASA may be very sensitive to hydrocarbons - you may
destroy the part by softening, swelling or dissolving it! Light white silicone grease is normally used with
nylon gears, it may be a possible choice for other plastics too.
Or the old fashioned wax (soft or hard variety) or goose grease with are very safe with almost all plastics.
Have also used 3-in-1 here.
DO NOT use ANYTHING that comes in aerosol form !
I saw that cause millions of dollars worth of damage to delryn bearings for a car plant that took us 3 months to fix even working 24/7
In addition to Marks comment about WD it also acts very well to DRAW dirt particles deeper into plastic parts causing even more problems.
Although it makes a great stainless polish. 