开云体育

This morning while the coffee was brewing I fashioned my own spring loaded worms.? The materials:

• Rubber bands cut from an old road bicycle inner tube.? This kind of rubber is very resilient, do not use household rubber bands.
• A strip of sheet metal about 1 cm wide and 5 cm long, just guessing, cut with tin snips.

Installation steps:

• Loosen the outer worm block by loosening two screws:
  • The screw at the bottom of the frame that the block is mounted on, just slightly so there is little vertical play.
  • The screw on the housing, this can be loosened a bit more.
• Wrap the rubber band twice around the screws at the bottom.? This should provide quite a bit of tangential force that pushes the outer worm block towards the motor side.
• Fashion the sheet metal to wrap around the rear edge of the housing and around to provide slight pressure on the housing screw.? This screw is directly screwed into the worm block so it provides slight lateral pressure inward that keeps the worm engaged without slack.? You can vary the pressure by positioning the screw, or simply bend it a bit more or less.? Not much pressure is required.
  • I should note that I don't use the Oldham couplers but flexible aluminum shaft couplings for stepper motors.? These couplers also provide some pressure but I think this should work with the Oldham couplers just as well.

I did this for both RA and DEC and slewed both around at full speed with my OnStep controller.? It seems to work fine, frankly.??I can't wait to try it out under the stars once the fog stops rolling in.? Here are some pictures:

The first 4 pictures are of the DEC worm block:









I only have one picture of RA, all you can see the rubber band and a glimpse of the sheet metal spring.? The other RA pictures were blurry.



As an aside, here's my OnStep controller to the right.? It's a Wemos R32 with a CNC v3 shield.? The Raspberry Pi 2B running Kstars and Ekos (client and server) is to the left.? I run it with 0.9 degree steppers with TMC2130 controllers with SPI for slewing at full step, microstepping 16x for tracking.? I start out using my Android cell phone as a remote over Bluetooth for alignment, then continue with Ekos and Kstars for tracking, guiding, plate solving, etcetera, remotely logged from my Galaxy Tab A with VNC.



I'll duck for cover now.? I've been on this board long enough to know what's coming, so fire away...