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Helical Crayford Telescope Focuser Model HC-2 Extremely smooth backlash free focusing... The HC-2 is for 2 inch eyepieces Made in Sequim, Washington State See below for the HC-2A Click here for the HC-1 Page See the note below about short Focusing Tubes July 2023 |
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Custom Mounting Bases... now available for the HC-1 and HC-2 focusers. |
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Images of Astronomer's Installations Minimum Height: .975 (24.75mm) |
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Why a Helical Crayford? Helical focusers have long been the answer to a low profile Newtonian focuser. One of the problems has been the annoying slop in the threads. Another problem is the lack of a travel rate fast enough for accurate focusing. Most helical focusers have a single thread which limits the travel per turn to about .125". With multiple lead threads, the rate can be increased somewhat, but still falls short of the necessary rate. Our Helical Crayford design permits a fast rate, smooth feel, no slop, and backlash free performance in a simple, lightweight design. Also, the HC-2 has no grease to collect bugs or get stiff in cold weather. |
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Set-Up and Operation The unique open frame design permits the Astronomer to mount the HC-2 at whatever height is needed to reduce the size of the diagonal mirror or increase the fully illuminated field. This is done using the supplied spacers between the threaded mounting holes on the Main Ring and the focuser mounting plate on the telescope. Installation on a curved tube will require careful shaping of the spacers, or a flat mounting plate mounted first to the tube. Focusing friction is adjusted by using a friction knob, which pushes the Teflon ball against the Focus Tube. Eyepieces are clamped in the usual way with a 10-32 nylon thumb screw, which prevents damage to eyepiece barrels. |
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Why 1.250" of Travel The 1.250" travel of the HC-2 will accommodate the flange focal lengths of most eyepieces available today including Tele Vue and VERNONscope. This will of course, depend on where the focuser is mounted in relation to the telescope's focal plane. The great news is that with the HC-2, the mounting height is easily adjustable after mounting. Maintenance The HC-2 can be disassembled and cleaned in under a minute without any consideration to the adjustment or collimation. The Focusing Tube can easily be removed from the Main Ring by simply loosening the friction adjustment screw and carefully sliding it out. |
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HC-1A Modification 10.20.06 Due to the large number of astronomers using very large heavy eyepieces, big binocular heads, and cameras, we have designed a backward compatable modification to the HC-2 to increase it's stiffness while using these heavy devices. The modification consists of replacing the two .750" long shoulder screws, part # HC-2-04 with a 1.000" long HC-2-04A. Corresponding stainless steel spacers, HC-2-14A (.193" ID, .313" OD, & .125" long), are inserted under each bearing to complete the stack. This spaces the bearings further apart thus increasing the stiffness. There is a small compromise to this modification as it decreases the travel of the focuser by an amount inversely proportional to the increased length of the longer shoulder screws. |
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The HC-2A showing the extended bearings |
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Also, the HC-2 can be switched between the Standard and the "A" in minutes. The -A Kit consist of two longer shoulder screws and four spacers and can be ordered mounted on new focusers or as a retrofit to older HC-2 focusers. |
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Prices HC-2 Standard = $117.00 + shipping HC-2A = $122.00 + shipping HC-2 Standard with A Kit = $133.00 + shipping Modification A Kit = $18.00 + shipping We do have quantity discounts. 2 to 4 = $115.00 std., $120.00 A, $131.00 std. w/kit |
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How to Order The preferred method is to contact us by e-mail with your order, be sure to include your name, address, (including country) and telephone number for order confirmation. We will then reply with the total cost including shipping. Mail your check payable to: KineOptics. If shipped in the US we ship Priority Mail . If you are out of the continental US, contact us and we will provide you the shipping cost and reply back. NOTE: Due to increasing PayPal fees, we prefer checks (drawn on a US Bank), or cash. We will still accept PayPal (with an additional 3% to cover the paypal fee) only if other methods are unavailable. We do not accept Credit Cards. Thanks, Joe LaCour |
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D1: HC-2 = .975 ~ 24.75mm D2: HC-2 = 1.450 ~ 36.8mm |
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NOTE: We have some short HC-2 Focusing Tubes left over that were made for a telescope manufacturer's specific application. They are 2.050" long instead of 2.425" which will reduce the travel by .375". They were reqeusted for a very specific application to prevent the Focusing Tube from clipping the light cone. I have only 6 pieces left so please inquire if you think this will help your design. We have had a few questions and here are some of the answers. 1) We have sold over 3000 HC focusers as of 2023. 2) Our focusers are machined to very precise tolerances which is necessary to provide accurate alignment of the focusing tube and proper operation. Use care when disassembling and cleaning. 3) The aluminum focusing tube must be anodized to provide proper surface hardness for the bearings. 4) We use expensive high quality stainless steel bearings and precision 303 stainless steel shoulder screws made in USA. The shoulder screws are necessary to mount the bearings. Full threaded screws should not be substituted as they are under size and do not properly align the bearings. 5) Large eyepieces, binocular heads, and cameras have been used successfully, but with slightly reduced stiffness. We have designed a backward compatible modification, Service Note 10.30.06, to improve the stiffness of the HC-1 when using these heavy items. |
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The story behind the HC-2. In April of 1999 a friend, Jerry Lodriguss, mentioned he was building a Dobsonian telescope. I mentioned a new focuser design I was thinking about and asked if he would try it out. The prototype HC-2 was made and delivered to Jerry for evaluation. Jerry was a very experienced astro-photographer and observer so I listened intently to his comments. After a second prototype, he and I were very pleased with the performance. Focusers have been sold to astronomers in Austria, Australia, Belgium, Brazil, Canada, China, Croatia, Czech Republic, Dubai, England, Germany, Greece, Finland, France, Hawaii, Hungary, India, Japan, Norway, Reunion Island, Spain, Switzerland, Sweden, Singapore, Scotland, USA, Wales, and New Zealand.7-2-2003 Here are some e-mails from Astronomers regarding the HC series of focusers. ______ Hello, Monday I received my 2 HC-2 focusers. I just want to let you know that I am very pleased with these well made instruments. I just installed the first one on my 12.5" f/5 dob and I am very pleased with my new focuser. The rotation is extremely smooth and focusing is no trouble at all. Installing was very intuitively and with the supplied spacers, mounting went without a glitch. I also want to express my feelings on how satisfied I am about the fact that several spare screws and teflon balls were included. I think this is a terrific deal and I 'll recommend the HC-2 focuser to the members of our local ATM and astronomy club. Kindest regards, Stefan Van de Rostijne, Assenede, Belgium
Joe, I just got the HC-2. I like it lots. It is very well made and it works much better than I thought. In a few months, I'll send you a picture of the completed scope. It will be a joy focusing eyepieces with your unit and at a fraction of the cost of other focusers. I am going to turn a solid base out of black Delrin and set the HC-2 on top. It should look nice. Thanks, ken graun
Hello Joe, I received the focuser in good order. Thank you. It is a nice piece of work and it works wonderful. Everything hoped for. I have not been able to point the telescope at the stars yet: cloudy all the time. Thank you very much. Best regards Harro Treur Hoofddorp
Hello Joe The Focuser arrifed in switzerland to Day. The Focuser is so simply and genial like a swiss swatch work. I'm inspired !! Thank you. I like to do trade with you againe. Sincerely Jürg
Joe, I have the HC-2 focuser. I love its minimalism & it is exactly what I need for my new scope. Now all I need is my primary mirror (due in March). Regards, Phil Watson Australia
Hiya! I saw a couple of your fantastic focusers at Stellafane this month and loved them. I'm sending a check for a 2" focuser by mail today. Hiya! My new 2" focuser arrived today and I am very happy with it. Since I had only seen them installed, I had no idea how light the thing is. That's great for my dob, it'll help keep the upper cage weight down. Thanks very much for a terrific focuser! BJ Drew East Lyme, CT
Joe; Received the focuser ordered from you. One phrase comes to mind. Really, really clever!! That is a really neat design that has been well executed. I hope you get almost rich off that little assembly. Dave Wattles
Dear KineOptics-people. Last sommer I came to know Your HC-2 focuser at the telescope of a friend of mine - and it worked very well. Now by building my own big Newton I find there are no focuser offered by the German-market optimized for Dobsonian scopes. The HC-2 is really nice focuser - gratulation ! Please send 2 pieces HC-2 to: Günter Rosenstein GERMANY
Hi Joe, I received the focuser yesterday, at last! Fast rate, lightweight, straightforward design. Nearly perfect. Best regards Miguel Remartínez |
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