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DIY Tripod, revised

clampdetail

I like the new 5×7 so much it makes my current homemade tripod seem like some stone age assembly of driftwood and chicken bones. But instead of completely starting over*, I thought I would mill down my old ash tripod to pare off a little weight and girth.  I’ve been trying to think of the best way to implement these cam lever locks into a 3-stage leg design ever since I stumbled across Dick Streff’s ingenious tripod 10 years ago-  http://www.skgrimes.com/library/old-news/dick-streffs-camlock-tripod.

I decided to try a variation- instead of the threaded rod and nuts protruding from the clamping frame and scuffing up the legs, lever locks, and whatever  flesh and fabric ventures too close, I threaded both ends of some 3/16″ SS tubing to use for clamping posts  so I could countersink screws flush into the clamping plate. Also, the bent U-rods were always difficult to make- once the second bend was made, the lever was locked in place and impossible to take apart. So I used some 1/4″ aluminum rod for the lever pivot, which can be screwed to the clamping posts and taken apart easily. I cut the clamping posts a little short so they can be tightened in dry weather (if it ever gets dry here). I also made the levers a little more user friendly, large enough to clear the sides of the legs so it’s easy to flip them when the tripod is collapsed. They’re made from walnut left over from the camera. I made a new yoke as well out of cherry. Only 8/4 stock I had, and didn’t feel like laminating a block of walnut. Made from a spoke-like array of three 1 1/4″ x 1 1/2″ x1 1/2″ pieces, double mitered the ends at 30 degrees. I drilled the pivot holes for the tripod legs before gluing and clamping it. The joint intersection makes it simple to find dead center to drill out for the mounting screw; plus it’s much easier to bore out the leg pivots in individual pieces so they’re square and parallel than when it’s an awkward  3-pronged yoke made from one solid block. To that a 4″ plate of aluminum is screwed as a bearing plate for the tripod head, and to help reinforce the glue joints on the yoke. Teak oil on the freshly milled faces of the ash, and a good 6 coats for all the new parts, and it’ll be ready to go. It is a patchwork quilt of dissimilar woods- ash, yellowheart, walnut and cherry, but it looks better than a 3 hour drive to the lumber yard. I’ll post a few pictures when it’s dry and all put together.

parts

New leg sections. All parts except top section (right) are still rough length here. I size tripods according to my height, tripod head and format size. That puts the center of ground glass of my 5×7 at about 6′ on level ground. When rough cutting for length, I usually add about 25% to provide extra for clamping overlap, uneven ground, as well as a little for Pythagoras.  I hate short tripods so it’s helpful to have some design wiggle room.

*Yeah I started completely over. I never really liked using wood for the cam levers. Too thin and they split, too thick and they look ridiculous.  I made a few different sets of levers for the Ash tripod- the ones made of walnut didn’t inspire much confidence. The larger cam pivot hole made the wood pretty weak. Then I made another set from cherry, but they went too far the other way. They looked like something whittled after nap time at summer camp. I was all set to order aluminum billet to mill some low-profile levers, but I  was out on a bike ride and noticed the quick-release axle skewers and had a eureka moment. Found some cheap sets on Amazon (3-pack, 2 axle skewers and 1 seat post clamp for under $10). They wouldn’t install properly with the way I milled the legs for the ash version, so made new leg sets out of Anigre I had laying around. Nice wood- tight grain, very lightweight and stable. I really wanted to use Honey Locust- always wanted to try it,  but they didn’t have any at Edensaw. I’m glad they didn’t- Locust would have been quite a bit heavier than the Anigre, maybe even heavier than Ash. Using rot-resistant wood isn’t exactly critical for a tripod. Traditional tripod woods such as white ash and maple aren’t considered  decay-resistant. Anyway, this is a great site for comparing and selecting wood for projects- http://www.wood-database.com/wood-identification/

I spend a lot of time getting all the rough stock perfectly straight and true before profiling. Obviously this is really important- if there is twist, bow or crown in any of the sections, then the range of the bike’s cam clamp will not be adequate when loosened to allow adjusting the legs smoothly.  So I start by milling all the parts over-sized and sticker them for a week or so in case there are internal tensions that will need to be milled out. I also mill enough to have some extra stock to practice the tool setups on.

The profiles themselves are easy to mill with a router table. A 1/2″ V-groove bit is used for the internal bevels, and a 45° bevel flush trim bit is used for the outside. The flat internal dado on the 1st section was plowed first with a 3/4″ bit, the bevels were cut last. A 1/2″ dado bit is used to crosscut the recess for the aluminum clamping plate on one side of the leg, and a forstner bit is used to drill the hole that locates the saddle washer for the cam clamp. Finally a 1/8″  groove is cut across the front and back faces of the sections near the bottom of each stage to locate the clamping posts. This helps to keep the clamp assembly in proper position when loosened.
nest

Nesting profiles. The corners of the legs that protrude past the nesting stage eventually get beveled flat (flush with the next section) so they will clear the clamping hardware, and the opposite corners are slightly chamfered so they nest better. My v-groove bit is really awful- it is slightly rounded at the tip so the solid legs sections doesn’t nest perfectly with sharp corners, but they nest just right once those outside corners of the legs are eased over with a block plane. After the final milling of the leg, a 3.25″ block of the solid leg  is cut off and screwed to the end of the 2nd leg section so it has a solid section for clamping. (The block is shimmed slightly with .002″ brass shim stock so the leg won’t bind.) The design is a compromise, but all this means is once the solid tripod leg is extended, height adjustments have to be made at the lowest clamp, they can’t be made at the middle stage since there is nothing solid for clamping past this solid block. But being able to collapse the tripod to under 30″ is worth it, and I rarely have to make height adjustments after the tripod is set up. Leveling is simple enough by forcing a spike further into the ground, or varying a leg angle.

boring

camdetail

Clamp test. The cast aluminum levers are very light and strong. The skewer set comes with cone springs and a saddle-shaped bearing washer, which sit in the hole. The spring behind the saddle has enough tension to keep everything aligned when loosened.  The hole is slightly over-sized so the washer can move freely with the spring. The cam pivot that comes with the skewers had to be bored for a new extended aluminum pivot pin made from 5/16″ aluminum rod. I need to get some different screws,  the flat screw heads are too big for the pivot pin. The clamp posts are 3/16″ SS tubing, threaded on both ends for 6/32 machine screws. Too late I found  threaded spacers at McMaster-Carr- those would have been much easier than threading all the posts needed for the tripod. But I only broke one tap.
Not pictured are neoprene washers, slightly undersized, that slip over the pin extension on each side to keep the cam lever from slipping out of position in the saddle when not clamped down.  (3/21/14: I swapped the neoprene washers out for some stainless steel retaining rings, the neoprene washers did not hold up very well. The new retaining rings have internal teeth that grip the pivot shaft and do not slip. The outside diameter of the retaining rings  are a little small, so also used a nylon fender washer on each side for a bearing surface.)
Also difficult to see are the shallow 1/8 grooves in the sides of the leg stages that locate the clamp posts and keep them from slipping around. Next time I will make these deeper, so they more positively hold the clamp rods when loosened.

crotch

Yoke detail. This was the only decent part from an earlier tripod build and I was able to reuse it here. The part is joined by double mitering  ‘spokes’ from 6/4 stock and gluing together. Once cured, the head bolt hole is bored out (the intersection of the joints make it easy to locate the center). The hole is stepped to provide room for the knob’s shoulder. A 1/4″ x 4″ aluminum plate is screwed to the top of the yoke, to provide a bearing surface for the head (sized for a Ries J250 double-tilt head). Finally a piece of bronze sleeve bearing is press fit into place to keep the knob’s threads from chewing up the hole. (The other two holes in the plate serve no purpose, they were in the piece of scrap I used to make this and I couldn’t cut around them. But I suppose drilling even more holes would shave a bit of weight off.) For the pivots, 1/4-20 bolts are used, with washers at every friction surface (4 total), and  adjustable-arm levers to tighten them down as needed. I actually have since swapped these washers out for larger ones. Fender washers are better for locking the legs down. Smaller-diameter washers tend to bite into and burnish the wood over time until it’s impossible to tighten the pivots enough.

legtenons

Tenons are cut on the legs for the spike hardware. Cutting then tenons is easy- just shim the leg center securely in a section of ABS pipe, clamp a crosscut sled and stop block on the table saw, then spin the pipe. The tenon is oversized enough so the brass fitting cuts shallow threads when installing.

spiketap

1/2″>1/4″  brass flared reducer fittings thread onto the tenons, and a 1/4″ x 4″ stainless steel lag is screwed into the leg. The hex head is cut off and the lag shaft is sharpened. The brass fitting not only reinforces the leg but makes a nice drill bit bushing for boring the pilot hole. Afterward, the fitting is removed and the threads and the tenon are coated with silicone to keep water and dirt out and glue the fitting in place.

spikes

Sharpened, silicon’d, and reassembled spikes.

collapsed

Collapses to 28″, weighs 5 lbs without the head. The clamping frames act as standoffs, they but against each other when folded up so the hardware doesn’t scuff the legs up.

extended

With a 25° leg angle the max working height is 60″  (not including head and spikes). I’m 6’3″, with my 5×7 on a Ries head that put the ground glass almost too high. All told the tripod cost under $100 in parts and materials ($20 of which was the teak oil) and a weekend to make, not including the lengthy drying time for the oil, or the wasted time trying to retrofit the old ash version.

clampdetail2

All wood parts finished with 3 thin coats of teak oil (Daly’s SeaFin). Stuff takes forever to dry here- if it’s ladled on it will never dry. But a penetrating oil finish is nice because it’s durable and very easy to maintain. It only needs occasional replenishing rather than a complete strip/sand refinishing, and it won’t flake or peel like a film finish.
One thing I would do differently on this tripod is to make the grooves on the outside of the leg clamping sections a bit deeper and more pronounced, so they would capture the clamping posts a bit more securely and keep everything aligned when loosened. I have one clamp assembly that pivots slightly, so occasionally the saddle washer isn’t seated properly when loosened. Those little cone springs under the saddles are surprisingly strong- it’s a little like holding a basketball underwater, it wants to pop out any way it can. And yeah, the clamp posts are about 1/4″ too short- they were sized for the wood cam levers, which had a much lower pivot point. No way I’m tapping a bunch of new posts though, that was to the most tedious part of this project by far.

clampdetail
yoke
wcam

Made a few modifications today- cut  the bevels deeper on the outer top leg section to make it more comfortable to carry, and replaced the bugle-head screws with socket-head cap screws.  Put the neoprene washers on the cam pivot pin to keep the cam lever from slipping side to side when loosened (swapped since for stainless retaining rings and nylon washers). Also added leg stops- a stainless steel rod between each set of legs at the top locates the collapsed position, and some standoff hardware on the backside of the legs runs into the clamping rod and keeps the legs from sliding completely out when setting up. Also, I swapped the standard sized washers at the pivots for fender washers so the legs lock down more securely.
A few tweaks are not pictured. A double-sided Velcro strap is anchored to one leg, and can be wrapped around the legs to secure them when the tripod is folded up.  I also cut a washer out of a yogurt lid to sit between the head and the tripod plate to make panning a little smoother with the Ries head. Some thin UHMW stock would be better, but the lid works surprisingly well.

Had a chance to take it out for a walk today. It works great, really couldn’t be happier with it. Had quite a few missteps trying to modify the old ash tripod, but I don’t mind screwups if something decent comes out the other side.  The aluminum clamps are super strong, no nervous creaking under the clamping stress that I got with the wood cam levers- I was always anxious about a lever failing out in the field and leaving me completely screwed. The saddle washer really focuses the pressure, and the cam is just eccentric enough to tighten securely without getting really sloppy when loosened.

Now if I could just teach it to walk behind me with all my gear. Or at least pull buttercups.

Updated hardware here-

Tripod remodel