Van Slyke Instrument's Machine Facilities
Mount any VSI Focuser to any Scope - Not just Meade & Celestron
AP, Borg, DFM, OGS, RC Optical, Takahashi, TMB, Vixen, etc., etc. - Just Call VSI
AP, Borg, DFM, OGS, RC Optical, Takahashi, TMB, Vixen, etc., etc. - Just Call VSI
How can the finest astronomical instruments, available anywhere on Planet Earth, be so reasonably priced? Simple, Van Slyke Instruments (VSI) is not a large, fancy CNC (Computer Numerical Control) job shop with high salaried designers, engineers, machinists and staff. Most important, VSI markets their own products (wholesale direct to you) so there are no dealer commissions, etc. that can seriously inflate a product's final price. You'll never see a VSI product marketed by anyone except Van Slyke Instruments.
All products are handmade on digital gearhead lathes and power feed digital mills, one at a time, by Paul Van Slyke. High accuracy [Tru-Set] 6-jaw chucks, with 0.0002" run-out, are used to maximize product concentricity, and KURT mill vises (made in USA) with vise surfaces that are ground parallel to 0.0001" for more accurate milling operations. VSI also uses Starrett (made in USA) and Fowler (made in Switzerland) digital height gauges for product layout, and high quality YUASA rapid indexing heads for extremely accurate dividing of circular stock. FYI, the lower right picture above is the layout and indexing stage in a production run of MasterGlide focusers. And, most products are personally hand signed (engraved) by Paul Van Slyke.
VSI products are aircraft-grade extruded 6061 T-6 aluminum and stainless steel construction throughout (except when other materials are structurally more practical or superior to metal). VSI uses a unique and distinctive finish on all products. The finish process is called glass beading, which is the same durable finish that is applied to high-quality rifles and handguns to give them [what I call] an "expensive looking" appearance. Glass beading also hardens the surface of the metal, similar to anodizing, but without harming the environment (see "Questions & Answers FAQ" link for more info). The finishing process is applied, using glass beads propelled at high velocity inside a direct pressure blasting cabinet, that actually cold works (hardens) the surface of the metal.
The value of your investment in Van Slyke products will appreciate over the years, because they are built to perform through the next millenium and beyond. For over 15 years, Paul Van Slyke has been creating ingenious astronomical products in his machine shop, and has been building telescopes for over 40 years. His reputation for manufacturing the highest quality instruments is known to be beyond compromise and without comparison.
From left to right above are: Trimos/Fowler 24" digital height gage, with 0.0001" resolution, on an isolation air bladder lift granite block and [blue] stand; Index 2hp vertical mill with XYZ axis power feeds, and XYZ axis Mitutoyo digital readouts with resolutions to 0.0005"; two 14" x 40" gear head lathes equipped with Anilam and Sony digital readouts, with resolutions to 0.0002" and European 6-jaw TRU-SET chucks. All the above digital mills and lathes have ultra-precise glass scales installed for repeatable accuracies. Foreground above right is a 7" x 12" metal cutting band saw with hydraulic feed.
VSI's machine shop is equipped with an 18" x 36" steel table topped with a 4" thick black granite block flat to 0.0001 inches. On this granite platform we use various high-accuracy height gages for layout and testing. From right to left is a Trimos/Fowler 24" digital height gage (made in Switzerland) accurate to 0.0001 inches, a Brown & Sharpe 12" height gage with gold faced, ultra-high precision German analog comparator gage with increments of fifty millionths of an inch, a Starrett 12" digital height gage (made in USA) with separate digital readout box, and an 18" Vernier height gage. The above instruments are used to perform various layout procedures before machining, and quality control testing after machining when ultra-high precision is required.
The Following are Examples of VSI Focuser Custom Machinings and Mountings
and are Available for Your Unique Scope - Just Call for a Quote
This custom built GIANT MasterGlide focuser now resides on a 36" Newtonian telescope in Ireland. The pictures do not impress this GIANT focuser's true size so, to help, note the 1.25" eyepiece (lower left picture above). This early focuser is very similar in operation and size to our newer 3" MacroGlide focusers. In fact, if you removed the built-in drawtube, they would be almost identical, except that the MacroGlides have a much shorter overall profile. The base plate is 6" by 7" and the focuser housing is 4.5" in diameter. This Crayford focuser has 3" of travel and a built-in drawtube to provide an additional 6" of extended backfocus. Note the dual focusing knobs for coarse and fine focus control and a gear reduced Pittman motor. It's the same type of motor that Meade uses to drive it's 16" SCT mount (overkill on torque). The drawtube not only has dual thumb screws but a TRUE compression locking mechanism for added equipment security. See pictures and info about this giant scope at VSI's INSTALLATIONS link.
The customer possesses two Meade refractors, a 102 and a 178, with stock Meade focusers which he wanted VSI to upgrade to our MasterGlide focusers. Needless to say, the Meade focusers left a lot to be desired, but we'll discuss that later. Al sent me the focusers by mail so I could machine and custom fit new visual backs with the Meade 3.25"-16tpi male threaded output. This way he could use any Meade large format accessory, including VSI MasterGlide focusers, and it provided his two refractors with much more versatility and functionality. Above left is a picture of the stock Meade integrated visual back/focuser, and above right is the VSI custom visual back with removable (threaded) MasterGlide focuser (model M4). Below left is a picture of the custom machined visual back, with the focuser unscrewed, ready for installation on Al's refractor and the custom 8" long extension drawtube (below center) to provide all the back focus anyone could ever desire. The cost for a custom threaded visual back (item #CMRVB) for your Meade refractor is only $250 (pictured below left), and the 6" long extension drawtube (item #DT6) is $125 (pictured below center) with the purchase of any motorized VSI MasterGlide focuser. Otherwise, the cost is double.
The lower right picture needs some explaining. I examined both Meade visual back focusers when I received them, just for curiosity sake. I was ready to be impressed by the utter size of the Meade focusers until I turned them over and looked inside. The pot metal casting looks massive from the outside, but the thin wall castings and the [less than] 1/8" thick wall on the rack tube was less than adequate. When I checked the rack tubes for "play" they both moved back and forth about 1/16 of an inch. When I looked closer, I saw adhesive tape on the focuser housing's three internal support ribs. These three lengths of tape along the focuser housing "skids" (for want of a better word) are what is suppose to support the rack tube.
Both focuser motors were a "catch 22" installation. The above stock Meade focuser motor looks beefy and strong and, in fact, it is. They even used metal spur gears. Whoa! I was trying to be impressed with at least the motor drive but, alas, I was seriously disappointed again. The motor shaft has a slip-clutch mechanism attached to the spur gear that needs to be adjusted so that you can simultaneously remote and manually focus the telescope. I tightened the clutch so the motor could move the rack tube, and it worked well, but when I tried to focus manually (slip the friction clutch) the shaft would not turn, so I loosened the clutch so the shaft could be turned with the focusing knob and then the motor's clutch would not engage the shaft. No matter what I did, the mechanism would not work as intended, one or the other, but not both.
Al's other refractor focuser (not shown) had a JMI focusing motor attached. I couldn't figure out why there were no knobs for manual focusing on the focuser, just a motor on one end, and a bare shaft on the other. Then I looked at the motor/shaft coupling and realized that the motor shaft was "hard wired" to the focusing shaft. Ah, no need for a knob on the other end of the shaft since you can't manually focus anyway. No disengage, no slip-clutch, no disconnect, no nothing. Don't get me wrong. I'm not complaining. I'm informing. - PVS
A special GLIDER 2, with a NCF drawtube, was custom hard mounted (but removable via three hex head bolts) to Ed Vega's 6" refractor back plate. Dr. Ed Vega also has a Super Power Focuser on his 20" Maksutov (see VSI's "User Installations" link for more info on Ed's "Big Mak").
Dr. Ed Vega passed away on December 16, 2003. He was diagnosed with brain cancer on November of 2001 and has been battling, and [supposedly] winning the battle, as there had been no recurrence. However, due to the fact that he had been receiving chemotherapy during these past two years, his resistance to other illnesses was low. He contracted pneumonia, which his system could not fight. The astronomical community has lost a comrade - an amateur astronomer of great renown. He will be deeply missed by myself and all who knew him, and his observatory at Skywatcher's Inn. - PVS
Another one of Ed's scopes is a folded refractor that a friend of his built for him, but Ed wanted the best focuser he could get for his new folded refractor so he thought of me (VSI). He detached the rear (aluminum) plate from his new folded refractor (pictured above) and sent it to VSI for my thoughts and recommendations. The above is what I came up with.
I believe that "detachability" or "interchangeability" is a mark of a thoughtful telescope designer who has his customer's best interests in mind. So I suggested that Ed have me machine a 3.25"-16tpi threaded docking adapter ring, just like the visual backs on Meade/Celestron SCTs, and mount the threaded adapter ring on his existing back plate. Then all he had to do was pick any VSI MasterGlide focuser model and "just screw it on." Down the road, this standardized docking ring will allow the utilization of any standard Meade/Celestron SCT accessory. Good idea, even if I do say so myself.
NOTE that this "custom docking service" is a simple courtesy that I try to extend to my valued customers. I will not provide this service to anyone who is not purchasing a VSI focuser. My custom mounting fee, either for hard mounting a VSI focuser to your existing back plate or machining a custom adapter ring (like the above), is usually around $150.
This very early vintage Astro-Physics (AP) refractor back plate/focuser combination was sand-cast from pot-metal, like the department store refractors. The above left picture is the original AP focuser back plate assembly before retrofit. The above right pictures are after retrofit. This is a very cheap and expedient way to create a refractor's "rear-end" but it leaves a lot to be desired in focuser operation, quality, longevity and [especially] functionality. I believe that all focusers, no matter what type of optical system they reside on, should be removable by whatever means possible (i.e. unscrew, set screws, etc.) so that upgrades, especially for imaging, can be easily installed.
The "play" between the focuser's rack tube and housing was about 5 thousandths of an inch so you could literally wiggle the rack tube back and forth in the housing - not good for even general observing, and totally useless for imaging. The "play" in the pinion shaft [shifted laterally] was about 10 degrees because the integral cast housing that holds the pinion rod (pictured above left) had no bearings or bushings at all - the pinion rod was rotating on the pot-metal casting itself so, over time, the wear became intolerable for the user. The old focuser housing was less than 1/8th inch thick - not enough "metal" to support a 2" format diagonal and eyepiece, let alone an extended imaging train. Even the broach slot was cast (not cut) and off the center axis by almost 5 degrees.
Of course, no denigration to AP is intended in this critical analysis. In the beginning, we all "cut corners" to make a buck, and we try to learn from our past mistakes. Even some of my early creations come back to haunt me, from time to time. It is my adament opinion that Astro-Physics creates the finest refractors in the world!
The back plate was salvaged (with it's original, vintage black wrinkle finish paint) by cutting off (with a lathe cut-off tool) the old integral focuser housing and machining an inner flat area on the outside of the back plate (see above right picture). This particular casting was so bad that the inner area of the casting was off by 1/4" in thickness from side to side. Needless to say, this surface was also machined flush with the front surface of the back plate. The center perforation was off by a bunch too, so the back plate was re-chucked (in a Bison 6-jaw Tru-Set chuck) and machined to center the perforation to within "2 tenths" (that's machine slang for 2/10,000"). The old focuser's rack tube was also salvaged [to save customer $ and utilize the AP's original focal reducer that fit inside the rack tube] and incorporated into a new, basic R&P Super Power Focuser housing with a separate pinion block using bronze [oil-impregnated] bushings to support the pinion shaft.
The cost for a custom threaded visual back (item #CAPVB) for your AP refractor is only $250 (as pictured above) with the purchase of any motorized VSI MasterGlide focuser. Otherwise, the cost is double.
Note that a quality bronze bushing will provide a zero tolerance, extremely concentric and durable pinion shaft support, and is preferred [by myself] over the more expensive ball-type bearings. However a high-precision ball-type bearing is also quite adequate to support critical control mechanisms like pinion rods or [even] worms for telescope drives. I prefer a bronze bushing because of concentricity considerations. Only a single "eccentricity" needs to be considered when mounting a pinion shaft in a bronze bushing, the shaft to bushing contact point. But four separate contact surfaces need to be considered when mounting any shaft using ball bearings - 1) the pinion shaft to bearing, 2) the balls to inner race, 3) the balls to outer race, 4) and the concentricity of the balls themselves. Both mounting methods have been used in critical support areas by Ed Byers and Thomas Mathis to mount their very high precision worm gear drive systems. A good example is my 30-inch Cassegrain mount which has a 20" Byers drive in RA, with it's worm mounted in ball-type bearings, which I was surprised to find when I purchased it. However, the scope's Dec drive gear is a Mathis drive, with its worm mounted in bronze bushings, which I believe will provide more accurate, concentric operation and support of the worm.
Another [what I consider] necessary upgrade was the [now discontinued] SPF's Railroad Bearing Stabilization System which provides a guaranteed zero image shift literally forever, no matter how much use or wear is imparted on the focuser itself. Other small, but important, upgrades were added, like a thumb screw to lock the rack tube (the original focuser had none), and the old single [skinny] thumb screw lock on the original rack tube (see above center) was replaced with large double thumb screws opposed by 90 degrees (which provides optimum lateral holding power) for added security. Then the new hybrid focuser was hard mounted on the old back plate with 3 Allen head hex bolts opposed by 120 degrees and countersunk into the rear of the back plate. A shoulder was machined on the inner rear of the focuser's housing to match the center perforation diameter of the back plate to guarantee proper centering of the focuser. Hex bolt concentricity and alignment was accomplished using an ultra-high precision YUASA rapid-indexing head. - PVS
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