/

[Chris S.]

Craig, that pdf certainly clarifies things. And finding an off-the-shelf AS clamp that happens to have a ¼ inch hole and a 3/8 inch hole on ¾-inch centers is unlikely. I did a little looking to see if any of the usual suspects offers a clamp with a mounting slot, rather than discreet mounting holes, but didn’t see one. This is perhaps something we should report back to Cognisys, suggesting ways in which their AS mount could be more adaptable. I was initially surprised, upon seeing the pdf, that the expectation does seem to be that the clamp will be mounted with the jaws side to side. But this makes sense for mounting camera via L-brackets or bottom brackets. For those of us with collared lenses or bellows, jaws facing fore/aft make more sense.

I switch between the two orientations quite often, using something like this: SUNWAYFOTO Bidirectional Double Clamp. My bidirectional clamp is of another brand, but I won’t recommend them for reasons that have nothing to do with their products. On paper, an item like this, combined with an additional AS plate, might solve the 90-degree issue for Brodie; but I would be leery of adding what amounts to three additional mechanical interfaces in an unknown system.

So Brodie, perhaps you’re back to drilling holes or using epoxy. Personally, I think I’d drill a hole somewhere. Drilling a hole in aluminum is actually pretty easy. Just use a nail of something to punch a small indentation first, use a drop of oil to lubricate the spot, and make sure the drill bit is decent. I say “somewhere” because it appears that the whole problem is solved if any one thing is altered: The StackShot AS mount, an AS clamp, an AS rail, or perhaps the bellows base. In my several ways, the simplest requiring a single unthreaded hole.

If you did go with the Wimberley plate—and at this point it looks unlikely that you would—you could always take a hacksaw to it if it were too long. Aluminum is pretty easy to cut. I’d avoid the Acratech (though I respect their products) because of the layer of cork. As the magnification goes up, anything compressible or springy is a potential trouble spot.

[Brodie Foster]

[Chris S.]

One of the cheapest Arca plates on eBay is actually a near copy of the Wimberley P-10 (#380340680597). I might buy one so I have something to use in the mean time and to see if it would work in that orientation. It may be able to be used in reverse with the length of the plate out towards maximum extension and the back edge of the bellows mount braced against the 'stop' for some degree of anti-twist? I'm not sure. It's worth a try for $23 shipped.

Seems like a plan. Gets you going, doesn't cost much, and may end up being your permanent solution. At worst, it's likely to move you ahead to where a solution will be more obvious. For myself, I often find that trying to work out perfect solutions in advance gives me "doe in the headlights" syndrome; accepting that something may not be perfect, but moves my rig ahead, tends to get me going again. And truth be told, I suspect that an antitwist feature may not be a deal breaker in your scenario. Nice to have, definitely; must have, likely not. If there is a devil waiting to jump out at you, it's much more likely to be vibration. But only moving forward with your rig will tell you. And if it does appear, you'll deal with it.

Otherwise drilling does sound possible with those tips, but to drill a seperate hole into a standard 38mm wide Arca plate and into one of the notches there seems to be very little room if I'm not mistaken. The red line shows (if I was holding the vernier caliper steady) roughly where the edge of the plate would be. Maybe there is just enough room for a small screw at the very start of the notch?

You don't really need much room to place a small screw. Be aware, though, that in the scenario you've outlined, you would need not only to drill a hole, but "tap" it--cut threads in the hole to hold a screw. This doesn't appear to be very difficult or to require more than inexpensive tools, but I've only watched it being done. My guess is that if you watch a few tutorials on Youtube, purchase a few simple tools, and buy a small piece of aluminum to practice on, you'll master it quickly.

Why haven't I done so myself? Don Wilson is smart and experienced, and I value his collaboration. When I hire his drill and taps, I also get his brain--and what we come up with together is better than what I'd come up with on my own. So I welcome chances to take things to Don. But I think tapping is something most of us can learn.

The drill-only scenarios I envision involve drilling the StackShot AS mount to permit fore/aft mounting of an AS clamp; or drilling an AS clamp to fit the holes in the StackShot mount (yes, I think that two mounting points are sufficient).

In the scenario you described, I think you could also avoid tapping by drilling the hole in the AS plate, placing a short length of brass, aluminum, or steel rod (hardware store stock, cut with a hacksaw) in place, and fixing it to the AS plate with a bit of epoxy. Lots of ways to get this done.

Best,

--Chris

[ChrisR]

If you used a fat (5 - 6mm) screw with a conical end, sloping in about 45 degrees from each side say, ( spin it up aginst a grinding wheel) it would center itself in the groove in the bellows base.
Or - look at the way the focus rail is held on to the Vivitar bellows. There are two springy "roll" pins at one end if I remember correctly. Quite good for a semi-permanent location. The aluminium is quite soft so eventually anything like that would wear looser. If you put your plate on, drilled a (3mm maybe) hole or two through both and tapped a roll pin in each hole through both parts, it wouldn't move, but you could separate it if you really wanted to .

There's Roll Pins and Coiled Spring Pins - similar but different
eg
http://en.wikipedia.org/wiki/File:Coile ... 341708.jpg

[Brodie Foster]

[Oskar O]

I'm sure that the P10 will work, even in the orthogonal direction, though it will obviously be more practical in the parallel direction.

I have a very small plate with an anti-twist lip from a Chinese company called KangRinPoche, but I would assume that they are not so commonly available. Novoflex has a very small plate that has anti twist protection, look for QPL AT 1 from here http://www.novoflex.com/en/products/cam ... n-qsystem/

I distinctly remember that the Novoflex plates didn't have any rubber until recently, so old stock might be available. Rubber is good for some applications, but for this I would prefer one with a bare metal mating.

[DQE]

With much concern that I'm not adequately following this thread, would the following 90-degree bidirectional clamp work for the needs discussed?

http://store.promediagear.com/Arca-Swis ... _p_17.html

Yesterday, based on another PM forum thread's recommendations, I took delivery of this clamp to make my macro rail's attachments easily rotate 90 degrees to accommodate either my AS lens plate or my AS camera plate. I need this for my Kirk x-y rails. The quality and stability of this clamp seem fine to me, in the admittedly limited uses I've made so far.

(I have no financial association with this vendor other than as a satisfied customer. Delivery was quick and email confirmations efficient.)

Hope this helps and isn't as irrelevant as I fear it may be...

[Chris S.]

. . .If you put your plate on, drilled a (3mm maybe) hole or two through both and tapped a roll pin in each hole through both parts, it wouldn't move, but you could separate it if you really wanted to.]

Good idea! (Though I had to look up "roll pin" to understand it.)

Brodie, Chris R.'s suggestion, performed on your inexpensive eBay plate and bellows base, seems like the best approach yet discussed for preventing twist. Sounds easy--just bolt your eBay plate onto your bellows in the normal wasy, carefully align it, drill a hole, gently hammer in the pull pin, and you're done. Nice!

Now that I know about "roll pins" and "coiled spring pins," I'll to get a few. They seem like like very handy problem solvers.

Cheers,

--Chris

[Brodie Foster]

[Brodie Foster]

[AndrewC]

Can't see it would really make any difference to vibration, you should just mount it where it is most convenient to use. If in doubt get a helper to hold it in place while you try and work around it in several configurations. For that matter while you're drilling, why not just drill an array of mounting points ? You could always come back later and drill some more but experience says it is better to do it up front

[Brodie Foster]

[Chris S.]

I held back because I don't know anything about granite as a working material. Like Andrew, I don't think where you mount your stand will matter in terms of vibration.

But I don't know how close to the edge you can mount without risk of cracking the granite. I'd be concerned not just about the drilling process, but the fact that you're going to mount what amounts to a lever in those holes, and then apply force (though rather little) to the lever that will pry in what is likely to be the granite's thinnest direction (assuming you have mounted close to the edge).

I've noticed that with granite counter tops, holes are sometimes drilled pretty close to the material's edge. But in your use, the load is different.

Is this actually a problem? I have no idea. Maybe talk with somebody who installs granite counter tops?

Good luck, Brodie!

--Chris

(edited--typos)

[ChrisR]

somebody who installs granite counter tops

Well as a handyman you get to do a wide range of stuff...

If the granite is half an inch thick and your holes are an inch from the edge it'll snap like a carrot.
If it's two inches thick and you drill right through and use spreader plate so the moment is applied along a line rather than a point, and several inches from the edge, you won't be able to break it. (Especially if the granite is fine grained and homogeneous rather than showing fibering, or whatever geologists call "grain".

How do I know? I don't. But having installed a few tons of the stuff and seen a few breaks, that's my feeling! I did metallurgy/materials science too, but we didn't DO worktops . I think granite shows precipitation in planes normal to strain direction while it's cooling.


And they look the same, from the top

Can you see the thickness of your column. or is it solid? And what's the diameter, and is it steel?
I'd be interested to work out its loaded resonant frequency compared to the ally tube on my Nikon stand.

[Brodie Foster]