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Looks really good Frank. Do you have designs you'd be willing to share? I guess it's made from Aluminium alloy, did you do it yourself or get a machine shop involved? How much did it cost to make?
Best wishes
Paul
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I second Paul¡¯s request for design plans
?Bill
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Bill, Paul, et al,? ?I had expected some interest along those lines and I haven't yet decided how I'm going to proceed.? I did work with a local machine shop and they used my drawings to produce the parts.? I supplied the 6061 aluminum bar stock and all other parts. The cradle arms are 1-inch thick.? The base plate is 1/2-inch thick.? I tried not to deviate from the original design. The radius of the cradle arms is fairly critical so it requires a large milling machine to accurately machine the 14-inch plus tube radius.??
I hope to post a thorough article in one of the astronomy sites.? I'll post here when its ready to publish.
Best regards,? Frank
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Thanks for this Frank. I have a non edge C14 and just to chip in, for the avoidance of the dreaded flexure for astrophotography, avoid rubberised material on the fork arms. Probably a thin felt type material to avoid scratching the scope would be good. I've been toying with the idea of making something like the HC for a while and your post triggered me to contact my local machine shop here in the U.K., where I obtained a ball park figure of ?300 for production costs, which is very reasonable.
Do you intend to fix your HC to the dovetail plate or bolt directly to the mount ?
best wishes
Paul
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Hello Paul.? I agree that ?300 is very reasonable. I was surprised by the cost of 6061 aluminium.? This version has approx.? $200 just in raw material.? Of course if I were to offer these for sale, I would not make a production run of less than maybe 10 units, so there would be the economy of scale.? Anecdotal evidence indicates that Andy Homeyer sold the 14-inch cradle for between 700 - 800 dollars.? In 2021, my estimate is somewhere in the $1000 - $1200 range to do it right with no short cuts, and based on a production run of 10 - 12 units.
I will be bolting the bottom plate (which is adjustable) directly to a Versaplate, as this C14 Edge will be mounted on a Paramount ME II.
Cheers,? Frank
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Correction
The radius of the cradle arms is fairly critical so it requires a large milling machine to accurately machine the 14-inch plus tube radius.??
Should read:? The radius of the cradle arms is fairly critical so it requires a large milling machine to accurately machine the 7-inch plus tube radius.??
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I got one of the original cradles a few years back and they are rock solid. I wanted to mount a FLT 132 on the same mount so I made a copy of the Homeyer half rings and just bolted them on upside down to effectively make a set of giant rings. Worked a treat and made the thing even more rigid, if that's possible. No need for SBS plates because its all along the axis of symmetry. My scope is also on a PME II and you will find the whole rig very effective.?
Rom
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On Thu, Jan 28, 2021 at 08:14 PM, rom62@... wrote:
I have one of Andy's cradles also and your mod to enable mounting your FLT132 seems excellent. Can you post a photo perhaps? TIA
Carl
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I too am looking forward to additional photos ?
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I think the machine shop I'm using for my cradle uses a CNC high pressure waterjet for things of this size, I'm no engineer, but when you see it working, it's amazing.
Paul
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Here is a pic during setup. It shows the symmetry and you can gauge the strength easy enough. Currently re-housing this gear at a remote site in Tasmania in a much bigger observatory.
Making the reflection cradles is pretty easy. You can get the aluminium laser cut just and use the original holes in the Homeyer to bolt it all together using 10mm stainless bolts. I created a .dxf file for an aluminium fabricator to use. They loaded it up into their cutting system and they were done in a day. Its a relatively simple fix for a very irritating issue. This setup required an extension bar for the PME II using 4 CW's but I am contemplating replacing this with another locally made 20+kg weight
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I also have one of Andy's cradles. Back when Andy made it, we discussed how best to add additional scopes for different uses. Moment arm was always a concern of Andy's, as he never liked overloading a mount. Our solution was to modify the cradle by adding mounting holes on the bottom flat edges to accept Losmandy plates. The result of that effort was a very versatile setup, but not one that stressed the Paramount. Here is a picture of the final configuration. I could guide with either refractor while imaging with the C14, or image with a refractor while guiding with the other one. All this worked well with the exception of the C14 mirror movement. But after 3 to 4 different mirror stabilizing experiments, the images became quite acceptable. ?
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Hi Frank - how did you find guiding your C14 by using a separate scope? Did it work effectively? I have just 'upgraded' from a C11 to a non edge C14. When using the C11, I couln't guide with a separate scope as mirror shift was problematic. I am guessing the same problem will happen with my C14, so I'm thinking to use OAG again. Separate guiding scopes give so much more choice of guide star - it would be great if it worked.
thanks
Paul
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Hi Paul,
Due to the design of an SCT, stabilizing the mirror is a complicated task. you can't "lock" the mirror, but you can do some things that will minimize the shift as it tracks from east to west. My C14 has been modified to address the shift created by the gap between the baffle tube and the draw tube. The mirror can also shift on the mirror mount itself and you cannot tighten the spanner nut enough to eliminate it without deforming the mirror, so modification #2 addressed applying pressure to the outer edges of the mirror in 3 locations to hold it steady. And the third modification was the addition of longer bolts to replace the transfer bolts that hold the mirror during shipment. Those bolts are too short to reach the mirror support once the mirror has be brought close to focus. This requires an external focuser since once all the stabilization is done, the mirror is basically fixed. These mods allowed me to use a guidescope with pretty good success. However, the best approach is as you suggest, use an OAG and separate guide camera. A good rotator is worth its weight in gold if guidestars are sparse and only found in one orientation.
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thanks for this Frank, you have confirmed my thoughts about OAG and SCTs. I use feathertouch and microtouch for focus control, so OAG is probably my only option.
Interesting mods you've done and I can se they'd be really helpful. Paul
On Mon, 8 Feb 2021 at 05:23, Frank S Barnes III < SBarnes@...> wrote: Hi Paul,
Due to the design of an SCT, stabilizing the mirror is a complicated task. you can't "lock" the mirror, but you can do some things that will minimize the shift as it tracks from east to west. My C14 has been modified to address the shift created by the gap between the baffle tube and the draw tube. The mirror can also shift on the mirror mount itself and you cannot tighten the spanner nut enough to eliminate it without deforming the mirror, so modification #2 addressed applying pressure to the outer edges of the mirror in 3 locations to hold it steady. And the third modification was the addition of longer bolts to replace the transfer bolts that hold the mirror during shipment. Those bolts are too short to reach the mirror support once the mirror has be brought close to focus. This requires an external focuser since once all the stabilization is done, the mirror is basically fixed. These mods allowed me to use a guidescope with pretty good success. However, the best approach is as you suggest, use an OAG and separate guide camera. A good rotator is worth its weight in gold if guidestars are sparse and only found in one orientation.
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I for got to mention, my machinist is willing to produce the Scope Cradle for the C14.? If there were 10 interested persons he would do a run.? At that quantity the price would be $999.? plus shipping.
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looks amazing Frank. My machine shop has mine underway here in the U.K.
I hope you get some good clear nights with it:)
Paul
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Thank you Paul.? ?I've needed to order another 30lb counter weight.? I should have it by next week end.? I don't want to try too much whilst this monster is un-balanced.
Cheers and Clears
BTW,? I used blue Loctite on "permanent" fasteners.?
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Frank A
