80% scaled Air Raid Siren by MlePh

thingiverse

This is a remix of the Siren by MlePh. It's been scaled down by 80% to fit comfortably in a 200x250 bed. However, once adjusted, it produces an incredibly loud sound! (even saturating a phone mic at 2 meters). "SirHaScaled v20.f3d" is the fusion360 file. I used various ball bearings for this project (mainly because I had them on hand): - 5x (4x10x4) : MR104 : https://www.123roulement.com/roulement-MR104-2RS.php - 1x (12x37x12) : 6301-2RS : https://www.123roulement.com/roulement-6301-2RS.php Changes made to the original design are: - Different bearings were used, implying adjustments to the crank axis - The central glued part was made thicker - Some of the frame parts were thickened for added rigidity - The front rotor propeller blades were adjusted to be thicker (scaling caused them to become thinner than the 0.4mm extruder) - An optional bearing was added to link in axis the crank one and the rotor (attempting to add some rigidity to the crank axis, which only had the big bearing and suffered transverse force during crank rotation) - Some holes were added to the frame for aesthetic purposes - The text was updated, now calling everyone at once for the morning coffee break at work EDIT: I split the "07 gear" into two parts because there's a weak point at the big bearing place. Instead, two files starting with "07" are used. I've replaced the "09" plus "15" part with only "09" and a 4mm diameter metallic rod (fits inside the small bearings). Settings: - Printed at 0.2mm layer thickness without support, except for the front propeller (0.1mm + support) - Printed in full infill only the small gears and the small axis; others were printed with 20% infill - Used PLA, but as mentioned in the comments, PETG is probably a better choice for the gears - Print 3x '19-screwFront01' - Print 6x '22-screwBack01' - Change the filament color before the last 3-4 layers for part '05-frontHolder02' to see the text (or fill the letter gaps with paint) - Concerning '01-frameCenter', in order to have the in model designed supports printed, I had to enable 'thin wall detection' option using Slic3r. Remove these 7 pieces after clearing the holes. Glued the parts: - '04-centerBearingHolder' with '01-frameCenter' - '15-axisLong01' with '09-gearSmall01' with '17-rotor02' with '16-rotor01' with '18-rotorFront' - '08-gearSmall02' with '14-axisSmall01' with '06-gearBig02' - '02-frameBack' with '03-bearingCap' /!\ Don't forget to sand a bit, once assembled and glued, the inside of '01-frameCenter' where the rotor spins, and the outside of the big rotor itself. There's enough play but it scaled down as well. I had some imperfections (elephant foot) and at high speed, the small frictions literally soldered the frame and the rotor (!). Sand all the axes that will be inserted into bearings, they should fit firmly but without excessive force.