Not too long ago I picked up a used Orion Guidescope, which is a 3.1” f/11 achromat. It came with a dovetail plate with holes in all the wrong places and some rings that I could not figure out how to mount. What I wanted was a simple package that had everything I needed to mount the guidescope to the main scope, so I set out on an internet search for just that.
What I came across was the Piggyback Scope Mounting Kit from ScopeStuff. It advertised no drilling required, all hardware included. Perfect. I selected my telescope (6” SN LXD75), placed my order and waited for it to arrive.
When the package came it looked pretty complete. Here’s a picture of the contents (minus the bar):
The rings looked nice. They hinge open, to make removing the guidescope easier. Each ring (the package came with two, only one is shown here) sports three screws to adjust the orientation of the guidescope. The rings came threaded with hex head bolts, each threaded with a washer and lock washer—presumably these are for permanent mounting of the rings. I didn’t use them.
The package also came with the cars and associated hardware—these are on the top right. Each contains a socket head bolt, and threaded onto that is a nut, metal washer, nylon washer, and (I believe) aluminum car. The idea is that you put the car into the metal bar, and tighten the nut down on the washers to hold it tight.
Getting Started
Excited that it appeared to have everything I needed, I got to work. First, size up the bar on my main scopes rings. Uhh, wait a minute. Something’s wrong here:
The holes don’t fit. At all. In fact, they’re pretty far off. I figured I must have been shipped the wrong bar, and emailed Jim at ScopeStuff to get the problem corrected. Well, as it turns out, they only have that bar with the different spacing (presumably for the larger scopes). He told me that he could fabricate a bar with the correct hole spacing, if I could email him what that spacing was.
Now, I’ll admit, at this point I was pretty frustrated. I mean, like I said at the beginning of this post, what I was looking for was a turnkey solution that required zero fiddling on my part… ok, maybe some fiddling (this is, after all, astrophotography) but no serious work. And the site didn’t say it wouldn’t work for my scope—under LXD75, it just said not AR-5, the refractor, but nothing about reflectors. And I was able to select my scope on the list! So you think they’d have checked to see it didn’t fit.
Well, they didn’t, and once I got myself out of too-high expectations mode and back into the land of aint-nothin-ever-works-out-of-the-box mode, i.e., reality, I set to work making it work.
Ok, Jim can fabricate me a bar. I could have him do that, and get the result in a week or so. Or I could just drill a hole myself, and have it today. So that’s what I did. And of course, this project provided a perfect excuse to go buy a new set of drill bits. No, you don’t need to run out and buy a new set of bits just for this one hole—but no one’s saying you can’t.
Now the bar that ships with the ScopeStuff kit has two holes—a regular hole, and one that is elongated, presumably to account for small discrepancies in ring distance. So if you’re going to drill a new hole, make sure you use the elongated hole as the one you ‘keep’, and that way, you don’t need to be too concerned about getting your hole exactly right. I marked the location in pencil and clamped my bar to a piece of wood:
The original hole size is ¼”, so this is what I aimed for. I started small:
And drilled out to the final size:
Now the observant among you will note that I didn’t do a particularly good job keeping the hole in the center of the rail. It’s a little tough to start the hole with a regular drill, and it kept moving about. If I had a drill press this would have been easy. That said, I wasn’t too concerned if the hole wasn’t exactly dead center, since I could easily take care of any difference when I aligned the guidescope using its rings’ three screws.
There was one other problem—the rail itself is not wide enough to allow the heads of the socket head bolts down into it without the top being widened; the pre-drilled holes all come with this complete. I didn’t have an easy way to do this so… and I’m not sure I’d recommend this, in fact, I probably wouldn’t, although it worked fine for me. Please be careful! Absolutely wear eye protection! Anyways, I took my ¼” bit, put it in the hole I drilled, pulled the trigger, and slowly angled it into the top of the rail. It bit away chunks, slowly, and I only had to do one side for a moment to make a gash big enough to get the bolt head in—here, take a look. This picture is a little out of sequence (I had another problem mounting which I’ll get to presently) but it shows the gash nicely. Not pretty, but it works:
Now it's just a matter of...
Ok. Perfect. Now, like I said, the image above was a little out of sequence, because it shows the bar successfully tightened down onto the main scope rings. Surely, now that the holes are in the correct spots, it’s just a matter of using the supplied hardware to tighten down the rail? Au Contraire, Mon Frère. The supplied hardware is all metric (M6 I believe). Through a happy coincidence I happened to have a pair of hex head bolts that were ¼-20 thread, and they fit the holes. So it appears that hardware type is issue #2 with the ScopeStuff kit. Ahh, well, no biggie, another excuse to go to the hardware store—which I did, for some ¼-20 socket head bolts. You see, the hex heads are too large to tighten down on the rail—you need socket head. I returned home triumphant, only to encounter this:
Argh! They wouldn’t thread in. They would go just a little bit, and then get stuck. I was afraid to force them too much, for fear that I had somehow misjudged the threads. Enough of this. I went back to the hardware store with everything—the socket head bolts, the hex head bolts, the scope rings, everything. Now perusing the hardware store, and trying pretty much every screw and bolt they had in the holes, that the only thing that fit were the ¼-20 hex head bolts. Nothing else. I noted that a lot of the ¼-20 stuff was marked as USS Coarse, which refers to the threads. I also noted, however, that there appeared to be a section of socket head bolts all marked SAE fine—which I reasoned were smaller threads, and would fit. Unfortunately they didn’t have any ¼-20 (although they did have sizes larger and smaller). Hmm. Time for some assistance.
I showed the hardware guy my dilemma, and he began the same procedure of trying every screw and bolt in the store in the holes. Once he was convinced it was actually ¼-20 thread, he began forcing some of them much harder than I dared, and I believe he saw me cringing. Ahh well, no harm, no foul. He asked me if the scope rings were a scuba tank holder. No, it’s for a telescope. Ahh, I had one of those as a kid, he says. Only got it out a few times. Some neat stuff up there, he says. Sure is buddy. Be happy to show you sometime. Now find me a gosh-darned solution!
Well, the guy decided that there was some gunk gunking up the top of the holes. Upon closer inspection, he was right—it was all black on the top, but silver down below. Looks like when they sprayed the anodizing on, they just sprayed it right into the holes as well. Can you believe that? How did I miss that? Sometimes all a problem needs is a new set of eyes. He hooked me up with a tap, which is what they use to put threads in holes:
Usually I guess you need a special tool to keep these straight and everything, but he said I’d be fine with just pliers if I were careful, since the hole was already threaded, and I was just cleaning it out. I was careful:
The first few turns were tough, then it threaded right on through. In five minutes my holes were clear, and the ¼-20 socket head bolts I had bought went right in. Hurray!
Rings
With the bar successfully mounted, it was time to try out these cars for the rings. Here’s one mounted on the rail:
Now here’s the problem as I see it. When you tighten it all down, per ScopeStuff’s instructions, the ring can still spin on the bolt! There’s nothing holding it in place! Now, I guess you can make the argument that once both rings are on, and there’s a scope tightened down, that it won’t matter, since the scope itself will hold the rings in place. But that just didn’t sit well with me. What if I removed the scope? Then the rings could spin (easily, I may add) and get out of whack. Furthermore, even with a scope in there, I reasoned that they could shimmy just a little bit back and forth—enough to potentially mess up autoguiding. So why take the risk? All this setup needs is one more nut to tighten the ring down as well. I tried it out using the nut from the other car assembly, but the bolt was just a little too short to comfortably get everything on.
So off I went to the hardware store to get more 6-1.00 nuts, 6mm washers, and slightly longer (6-1.00 x 30) socket-head bolts. What I did was thread the bolt and a washer down through the ring, and tighten it fast with a nut on the other side:
The washer takes care of the fact that the hole isn’t quite large enough to tighten the socket-head bolt down completely. I would have liked another washer on the bottom, but, alas, I only bought two. Ah, well. I plan to keep an eye on it to make sure it doesn’t loosen—although if it does, I’ll be no worse off than I would have with the original kit.
Next I threaded on the second nut, another washer, the nylon washer, and finally the aluminum car, and mounted the whole thing to the rail in the normal fashion, tightening it down with a pair of vice grips since my pliers were too thick to avoid loosening the first nut:
And that was that! Here’s the whole assembly back on the mount:
The Final Verdict
So how would I rate the kit? The rings are great. As I said, however, the kit was not at all a turnkey solution for my scope. The holes didn’t line up and the supplied hardware didn’t fit. That said, though, I’m pretty pleased with it, although in retrospect I’d go with something simpler. There’s a bit of play since the scope itself is held so far off of the rail by relatively thin bolts. Supposedly the cars are a more convenient solution than permanently mounted rings, but honestly, how often are you going to be moving the rings up and down the rail? And when you factor in the fact that the cars themselves are unable to slide past the socket-head bolts that hold the rail down, the convenience factor is lost—you have to remove the rail to reposition a ring in the center. The instructions that come with the kit have a second picture that supposedly shows you how to permanently mount the rings to the rail, but it doesn’t appear that their method works. They show a bolt threaded through a washer directly into the aluminum car, and tightened down—but when you try that, the thing ends up getting snug only when the ring itself is at crazy angles to the rail (i.e., not straight). Their solution is to say that the ring base must have the hole drilled out to ¼”. Ugh. The heck with that.
I will say this, though. Now that I have it all set up and everything, it seems to work great. Haven’t had a chance to try any auto-guiding through the setup yet, though, so the real test remains...
… but dang it, don’t it look sweet!
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