Building the body
We chose 12mm plywood for the main body as it is easy to work with hand tools, and strong enough when cul to intricate shapes. Once it was accurately marked out, we used a coping saw for most of the cutting. An electric jigsaw Is an effective alternative, but holding the small parts while cutting requires care. When we drilled the holes in the two sides, we taped them together and drilled through both. This means that should you make a small error, it is repeated on both parts so the focus shafLs will still be parallel.
CulLing Lhe threaded M6 rod with a hacksaw can leave a sharp burr or damage the thread. To avoid this, screw on a nut just beyond where you want to cut, saw through and then file across the end; when you remove the nut it will tidy up the thread ready for use. Our rubber tap washers were rather tight on the shafts so we drilled them out. The resulting holes looked a bit untidy, but once pushed on, the washers fitted well. Normal nuts may work loose In use, so we used Nylock self-locking nuts in strategic places, Ifyou can't get these you can use a pair of nuts together, tightening the second one against the iirst to lock them in place. Washers prevent the nuts from rubbing against the wooden sides.
The paint finish is optional, but does stop the plywood getting grubby. You may prefer a stain or varnish finish to suiL your telescope. Paint it before you assemble it, though, or the shafts will get stuck.
Mounting the focuser on a flat-sided telescope is a simple matter of drilling and screwing. I( you have a round tube, you will need to introduce some packing strips to suit the curve.
Once assembled, you may need to tweak the rubber washer positions to ensure that the drawtube runs centrally and wiLhjust the right amount of grip.
With your focuser complete, you'll be focusing in style, rewarded by the knowledge that equipment built by your own hands has focused disLant starlight. ©
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