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Accessories for Quantum 6

Started by hubblejim, 08/26/2007 01:59PM
Posted 08/26/2007 01:59PM Opening Post
Just dug an old OTI Quantum 6 out of mothballs. Everything seems to be in working order except for a little tarnish here and there. Some questions:

1) Will Meade or Celestron equatorial wedges fit the Q6?
2) Sources of camera adapters for the axial fitting on the control box?
3) Only eyepiece is a 16mm Brandon? Any recommendations?


Posted 08/29/2007 11:37AM #1

James Kelley said:

Just dug an old OTI Quantum 6 out of mothballs. Everything seems to be in working order except for a little tarnish here and there. Some questions:

1) Will Meade or Celestron equatorial wedges fit the Q6?
2) Sources of camera adapters for the axial fitting on the control box?
3) Only eyepiece is a 16mm Brandon? Any recommendations?



I have a quantum-4 and the base of the four fits the 8" wedge. My recollection is that 6 would fit on the same wedge. I have a Televue 32mm in addition to the 16mm University Optics Konig which is an excellent eyepiece. Since you have the 6 you can use 2" eyepieces. I have an excellent 55mm UO Plossl
Posted 09/08/2007 09:49PM #2
Here is some good info for you. Feel free to IM me for a complete copy along with pictures, literature, history, etc.....

Optical Techniques Quantum 6 Restoration

I would like to thank Allan Keero at Davro Optical, Phil Houston, and Paul Feffer for assistance with my restoration.

Interesting story (short version)….I collect and restore vintage telescopes. In August 2006, a listing was posted on Ebay for a Quantum 6 telescope. I bid on it. Turned out the auction was a fraud (what’s new for Ebay?) A few days later I got an email from an Ebay member saying he had a Q6 and wanted to sell it locally. Yeah right! I thought. I figured there was a 50/50 chance of seeing a scope and getting mugged. Keeping this long story short….I drove to downtown LA high rent district and bought the scope from the original owner (I later learned he was a principal at Lunday Thagard Oil Co who OTI has as the original owner).

When I brought the scope home, I had my usual thought of whether I could bring this back to life. All of the aluminum had corrosion, the primary needed recoating, the diagonal was tarnished, and there was no power cord or lens cover. Further testing revealed the Barlow was set wrong, the diagonal was misaligned, and the slow motion on the dec axis was stiff. But, nothing was broken, the tube was in GREAT condition, and I could tell the scope had little use and needed restoration.

My parents have always said I like to take things apart and see if they float. I guess that is what took me to mechanical engineering. Nowadays, I take things apart and actually fix them. I have disassembled and restored about 50 scopes. No Maks. No Questars. NO Quantums. But, since this all came out happy in the end, I thought I would give some tips to future owners of Quantum telescopes.

OTI became Davro Optical. For 25 years Davro has serviced the OTI scopes. As of today, 10/17/06, I have been told that Davro no longer services the Quantums. The reasons are not important, business is business, and may change in the future. So, you may ask “where does one get parts?” A better question is “Will you ever need original parts?” Probably not. But, if you need them you can check with Allan Keero at Davro, Warren at Photon Instruments, me, and a host of others who have acquired parts over time. But, read on….

The first order of business was clean up. I use automotive aluminum paste polish. All of the knobs are easy to remove with a hex head set screw. I took them all off and polished them until I was blue in the face. Good for some, not for others. If you are really having trouble, I suggest 0000 steel wool. Then, re-polish to take out the fine scratches. For fine work where you do not want paste all over, I recommend Eagle One Never Dull Aluminum Wadding Polish. This is just a can of wadded up cloth with Magical powers. Lots of polishing. I use a toothbrush, steel wool, or wire brush to clean the edge grooves of the knobs. Start with less harsh and move up only as necessary.

The tube looked great, but the dewshield was really scrapped up. Duplicolor Ford Midnite Blue T218 is the color OTI used for the scope. NAPA ordered it for me and it arrived next day. I repainted the dewshield. Note here is that although I shook the can well, the paint color was not an exact match. I bought a second can, same result. I would not suggest using this paint as a touchup.

Time to go nuts and get the primary mirror out. I first tried my spanner wrench to remove the corrector. Ouch. Too tight. So, the way to get at the primary is to have someone hold the control box and turn the entire OTA counterclockwise. Once you make that first turn, but sure to put the scope vertical with the control box on the floor/table. It will take several turns, but it will come off. When you pull it off, pull it straight up or else you will hit the mirror and damage it.

Using your tool of choice, mark the placement of the mirror with respect to the control box or the focus shaft. See the Springs? I hate it when I encounter springs. Do not worry. The mirror is held by the large aluminum plate as seen here. The springs provide no support minimal support.

This plate is threaded and the black tube threads into the plate. Turn the focuser until the mirror is furthest from the control box (opposite what is shown above) (this will help reduce pressure on your next steps) Hold the plate and slowly unscrew the black tube counterclockwise. Try to keep the aluminum plate with downward pressure. Do NOT let the mirror be pressed back up into the tube. It is being forced that way. Do like I did and take a long look at this before you start. After a few turns, the mirror will be freed. Note the O-ring and retainer under the mirror. Note the few parts here. All, springs, O-ring, and retainer could be found from McMaster Carr and other sources. The order of things is black tube, mirror, O-ring, retainer, plate.

Send your mirror off to QSP/Infinite Optics in Santa Ana, CA. I spent a lot of time and did quite a lot of research to determine the composition of the original coating. I spoke with Dwight Cumberland at Cumberland Optics (original manufacturer), Allan Keero, and others. I ended up speaking extensively with the coatings engineer at QSP. The mirror came out AWESOME. QSP provides a nice graph, mine at 98%. QSP said the mirror was extremely smooth and easy to work with.

While the mirror was out, I checked the corrector from inside the tube. A little bit of pressure and I was able to get the retainer off. Index the position. Use a spanner wrench. Edmund sells a nice one. Mine was in superb condition as was the secondary. OTI guys suggest placing a .070 O-ring cord underneath the corrector to provide support, ease collimation, and provide a better seal from moisture. I had already replaced the corrector when I learned this so I can not say if it works.

Now, you are going to want to get into the control box. First off, the hex head on the bolts is the crazy 7/64 hex wrench. You will not find that one on your Huffy set. You will take all the bolts off and then the control box will not come off. Ok, screw them all back in :- ) In the picture above I have marked the retaining clip. You can only see this when you turn the focuser clockwise as far as it will go (as in picture). Pop this off with a flathead screwdriver. Now, go back and remove the bolts holding the control box to the mirror assembly support. Whoola! The box comes off, the brass threaded sleeve below the retaining ring flies off, the springs jump. All is good. Ok, no springs flying J

The Barlow is available for cleaning, same goes for the diagonal. The Pictures below shows the set screws that are used to align the Barlow and diagonal. No idea how these could get off, but you can use those screws to realign everything. Here you can also see the focuser belt. The piece everyone says is bound to fail. Well, mine was original and looks great. To determine this, use a 10x loupe with a flashlight and examine the edges of the belt to look for fraying. I currently have extras if you need them. But, you will not. Just another easy part to get. If you are reading this 20 years down the road, know that the belt is a sewing machine belt and can be had at Choose 48 as number of groves and then any of the first 3 work. Urethane Polyester looks like an exact match. Replacement is easy once you have gotten this far.

Hopefully you are looking at this and saying “Direct drive would be easy” I agree, drill a hole in the back of the control box, extend the threaded focuser shaft, provide a support sleeve for the longer shaft, a couple bearings…easy. I have not done this as I like the focuser on the side. But, Warren at Photon (not recommended) will do it for $350. I will do it for $100.

Replacing the focuser belt at this point would be a matter of marking the location of the gear on its rod with a permanent marker. Do the same for the position of the set screw sleeve you would have to remove to be able to slide the focuser belt over the gear on the gear pictured in the back. The one in front is easy as you can just place the belt over the gear.

Notice that with a little research, there is hardly a part in there that could not be replaced. Maybe the diagonal mirror, but even then you could use the axial port. But, even the diagonal mirror could be found.

Put the control box back together. Push the brass focuser sleeve from aluminum mirror plate into place. The position is not important at this time. The springs should still be attached at the top and make sure they are in the set hole on the control box. Leave the clip off the focuser shaft.

Hey, the mirror is back! Oh my, never collimated a Quantum before. No worries. Ok, most likely no worries. Notice the incredible machining tolerances of the parts. The black tube slides over the center post. You can not jiggle it at all. Put the black tube into the mirror center hole. Notice the tight tolerance. Ok, screw the focuser all the way back out so the plate is furthest from the control box. The springs should be exerting minimal pressure. This is a bit tough. Line the retaining ring up over the hole in the aluminum plate. Do the same for the O-ring. Place the mirror over the center post and set in gently over these two parts.

Ok, new paragraph for a reason. Slide the black tube over the center post. Come down to the mirror and look at all sides to make sure you will not hit the mirror. Notice you can not see the threads for the aluminum plate. Do not disturb your original set up. Push the black tube through and thread it into the aluminum plate. You will most likely have to take several tries to get it all lined up correctly.


Thread the tube into the plate. Just before it hits the mirror, time for some measurements. Use a digital caliper and measure the distance all around from the top of the control box to the top edge of the mirror. It should be the same all around. Notice you can move the mirror slightly to raise or lower a side. Set your mirror at your alignment points from before. I know, what kind of collimation/alignment method is this? Well, more to follow.

Screw the black tube down until the mirror is just slightly hard to turn. You focuser shaft should be aligned in the middle of the hole and at 90 degrees to the control box. If not, note that the brass sleeve can be shifted. Do so to align. Check mirror. Check spring for vertical alignment. Turn the focuser clockwise to raise the threaded focuser shaft just above the brass sleeve. Replace the retaining clip.

Now you have to put the OTA back on. Place the control box face up on a table. Have someone hold it level. Place the OTA over the center post and SLOWLY over the mirror. Thread it onto the control box. This is NOT easy. The threads are VERY fine. It should thread easy.


Time for a star test. I suspect you will be shocked how close it is. The reason is that Quantum set the scope up so that the machining controlled the alignment. I am sure you noted that there are no collimation screws, bolts, shims, nothing. But, you may well be off a bit. Amazingly, the process is long, but simple. Collimation is done by rotational alignment of the corrector and primary. This takes time, but you need to rotate the corrector little by little, retesting after each rotation. An artificial star will make this a whole lot easier. If this does not do the trick, you get the next stage. Rotating the mirror in the same manner. I did this and then rotated the corrector a full circle for each 1/16 turn of the mirror. A little over ¼ around the mirror, the spot hit. Make sure your black tube is now semi-tightly on the mirror so it cannot turn, but at the same time does not put stress on the mirror.

Note: Lumicon 6.7” Vinyl dust cover ($9.95 at scope city) fits perfectly over the dew shield