Progress on the new tracker with an ACME thread worm

I have now made a new worm gear and worm with a 10×2 ACME threaded rod (10mm diameter with a 2mm pitch). I milled a few slots into a section of the ACME threaded rod to try and make a tap. It works quite well but this “ACME tap” cannot start the aluminium worm blank in the same way as the M10 thread would.

Tracker 5 April 15-1147

Tracker-8956 IMG_8951

This meant that I would have had to manually cut or saw the starter slots into the blank for the ACME thread to lock onto. It’s quite a bit more work with about 200 odd slots to cut! Eventually I got a M14 tap with a 2mm pitch and I started the worm with that until there were well defined teeth in the worm wheel. I then changed to my home made ACME tap and continued until the worm gear was done. A new ACME worm was then mounted on the guider with two pillow blocks that I used previously. The assembly is quite heavy but very solid.

Tracker 5 April 15-1148

Tracker 5 April 15-1149

The worm has not been cleaned up yet. I still have to spend some time with the worm gear pair and some metal polish and let them work themselves into a smooth finish. There is a small section on the worm that is not great and I will avoid using that section when I use the tracker under the stars.

The tracker will be mounted on a Meade wedge at first until I make a more solid wedge out of a few steel plates. The orientation of the tracker’s RA shaft is 90 degrees different to the normal. Fortunately the Meade wedge can adjust far enough and I can reach the southern celestial pole with this unconventional configuration.

Tracker 5 April 15-1156

Tracker 5 April 15-1158

The thick aluminium plate will be cut smaller at the top end to allow for the mounting of a DSLR camera and a guidecam on a ball head. Later I will have to figure out a way to mount an ED80 and a Meade 8″ SCT optical tube on the RA shaft.

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