Lessons Learned

LXD75 Mount Modifications

Submitted by Karl Poirier - Nov 19th, 2005
Learned: Personal Experence

I had a great warm clear night last Friday and finally started to get somewhere with this beast, but after removing the motors twice to tighten the gears, I decided that modifications, major and minor were in order.

I am blessed with a family owned hardware store that has just every type of fastener you could want, and there is probably one in your neighborhood too.

These little mods have transformed this machine into a much more pleasant experience.

Article by Karl Poirier - Guelph, Ontario, Canada

Here are the problems and solutions in increasing order of importance.

Problem #1

A minor annoyance in that the Tube Ring Clamp bolts are held captive by having threads in the upper half of the Ring. When loostening these bolts, they will thread up into the upper ring half and bind.

Solution: install a 5/16 Circlip on the bolts (see photo)

Problem #2: Sloppy Tube Rings

The Tube Ring hinges are just two loose M5 screws that can't be tightened as they have no slip mechanism.

Solution: Replace the screws with a single M5 x 50mm screw and self locking nut. As the screw will go through threads on both halves of the ring, there will be a tendency to bind if you are not careful. As the inner bosses are threaded, the tendency will be for the hinge to tighten as it is closed. I found that setting the ring almost closed and running the screw through both bosses results in a hinge that opens enough to install the tube, but does not wobble or flop around.

Problem #3: Finderscope Location

The location of the finderscope behind the eyepiece is almost impossible to use, especially if, like me, you only have one good eye.

Solution: I formed a bracket from 0.075 aluminum, and designed a couple of little bars as can be seen in the photos.

This bracket mounts on the top holes of the scope rings, which further strengthens the ring assembly. The finderscope is mounted to the bracket and is now almost always on top and easy to use. I have CAD drawings of this bracket for anyone interested.

Problem #4: Eyepiece Location

Now that the rings are solid, the problem of getting at the eyepiece can be addressed.

Solution: It does not take much to hold the 10" OTA in place with the rings loose enough to spin freely. I used two little brackets that come as part of magnetic cabinet door latches and Pop Riveted them to the OTA (Two of them at 120 degrees from the eyepiece. Beauty eh! See photos

And Now!! The big one!

Problem #5: Spur Gears that will not stay tight no matter how often you go at them.

Loosen the gears and re-tighten them so the setscrews are NOT on the shaft flats.

Carefully drill a 5/64 hole somewhere in the gap of the shaft flat.

Install a 2-56 x 1/4 Type "F" thread cutting screw in the hole.

Voila! removeable, but never slip gear attachment.

By the way, if you do break a drill bit doing this, well, you have the tightening problem solved, but removal might be tricky.

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