New Mount For 6" Celestron Dobsonian

[SteveTheEgg]

I have this http://www.celestron.com/c2/product.php?ProdID=20 scope, and unfortunately it has been broken for quite sometime. The mount was never good to begin with and has always inhibited my viewing. It constanly slips and now the handle has completely broken off. So, I'm in the market for a new mount. I'd like a tripod but I'm not sure if that's possible. Anyway, I'd really ap preciated some recommendations. Thanks in advance!


-Steve

[Siguy]

Hmm, well, for a new mount that can hold a 6'' F/8 tube, you're basically stuck with a unwieldy German equatorial mount, as very few people make altazimuth mounts that can support a tube of that length.

But as for GEMs, a 6'' F/8 doesn't need too much of a mount to handle.

A Meade LXD75 (http://www.adorama.com/MDLXDMTWA.html?searchinfo=lxd75&item_no=3) or Celestron CG-5 (http://www.adorama.com/CNCG5C.html?searchinfo=celestron%20cg-5&item_no=13?searchinfo=celestron%20cg-5&item_no=13) would be an excellent choice. I've also heard no complaints about Orion Sirius and Atlas EQ-Gs (http://www.telescope.com/control/product/~category_id=mounts_and_tripods/~pcategory=mounts_and_tripods/~product_id=24335). Even a Vixen Polaris clone, like the Orion SVP (http://www.telescope.com/control/product/~category_id=mounts_and_tripods/~pcategory=accessories/~product_id=09829) will work quite well when equipped with a proper dual axis drive, except for long exposure astrophotography, which will be still be possible but difficult. Don't get the GoTo version of the SkyViewPro, however. When compared to the GoTo CG-5 and LXD75, it's quite a ripoff being that it is more than either and is lighter duty.

Actually, I'd go with either an Orion or Celestron, since it matches your color scheme.

[Hornblower]

If you wish to do photography, I would go with Siguy's advice. If you merely wish to do what the original mount was supposed to accomplish, I would keep the existing mount, but modify it the way John Dobson himself would have built it. As an experiment I built a Dob mount for my old homemade 6" f/8 Newtonian, using scrap wood for the structure and Teflon pads against Formica or stainless steel for the bearings. If you do not have the necessary carpentry tools or knowhow to do it yourself, or if you have trouble finding the necessary bearing materials, perhaps you could get good assistance from someone in an astronomy club in your area.

The azimuth bearing consists of three Teflon pads on the base, with the Formica-clad bottom of the rocker box resting on them. A simple bolt in the center keeps everything centered. For the altitude bearings, I made semicircular cutouts where the bearings on your mount are, and put two Teflon pads in each one, just below the level of the altitude axis. I mounted wooden disks, about 3" in diameter and covered with strips of stainless steel, on a wooden box that clamps around the tube where your horizontal shaft is. I adjusted the spacing of the pads by trial and error, until the drag was about equal in both dimensions with the tube inclined 45 degrees and grasped at the focuser.

I realize my verbal description above, especially of the altitude bearings, may be clear as mud. I can post some sketches if you wish. Just bear with me and give me a few days.

If done right, this type of bearing gives buttery smooth action, staying put under a light touch but moving smoothly with virtually no grabbing when pushed or pulled firmly but gently.

If you wish to have an equatorial mount rather than an altazimuth, you probably will double the final gross weight and spend many times the money to get anything near the steadiness of a good Dob.

For quickie visual work I can do just as well with an altazimuth as with an equatorial in most cases, provided I have good charts and can see the stars down to the chart's limiting magnitude in the finder.