> From: Chris Albertson [mailto:[email protected]] > The noise is caused by tooth shape. I think the sound is caused by air > getting pushed out of the grove in the belt and pulley and very high rates > and then the teeth slamming together. A lower precision printed pulley > would interlock tighter with the belt. The slamming would be a little > harder. If noise were important, you would select a more modern rounded > tooth shape. Profiles like GT2 have less noise and less "slip" and a bit > more strength for the same size belt. and importantly the teeth don't slam > together On these belts the belt/pulley interface is much like a sine > wave rather than a square wave. > > I run GT2 timing belts as fast as the stepper motor can go and don't hear > any belt noise. All the noise comes from the motor.
The plan is to go to the rounded shape as previously suggested. The issue is cost and making dumb decisions that then cost. So initially I wanted to be sure that the motor and the knee would behave and the cheapest way was 16 minutes worth of Natural gas (240k BTU foundry) and old window frame extrusion ingots. And so far maybe a 1/4 of a reel of 1.75mm PLA. Oh and one 6mm drill bit that snapped off when the 6mm clearance hight I'd programmed in didn't take into consideration the flat washer under the hold down bolt. And of course to go to the first drill location it went straight across that 7.5mm high point and half the drill bit went flying. I'm only out a little bit of time really and it's been very educational. For example this time I ran the CAD/CAM as a metric drawing and G-Code so G21 was needed. And the Tick Box on the Axis display to show mm. But for some reason yet to be discovered, the HB04 USB wired pendent still showed and did everything in inches. Now that I have everything somewhat functional and it appears to work well with only 3.2:1 instead of the targeted 4:1 I can look into metal pulleys. Even the motor plate size was iffy because I haven't modeled the entire knee and so fit with the slightly longer (encoder) Servo compared to the Stepper (no encoder) was also up in the air. John > > On Fri, Jan 1, 2021 at 11:54 PM <[email protected]> wrote: > > > On 2021-01-02 06:53, John Dammeyer wrote: > > > I have noticed the 3D > > > printed pulleys are noisier than the metal ones. > > > > I wonder whether that is because the surface of the teeth will > > inevitably be rougher than if they had been die-cast or machined? > > > > > But the noisy grind > > > of the stepper motor is also gone. > > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
