Whoa! The sequencer prototype is built, configured, and running on my desk next to me. It has been a long trip in the meantime and I’m eager to share the build here in this post. Overall I spent about thirty hours at the bench putting this thing together due to a lot of routing, planning, and testing that doesn’t necessarily come through in the photos. Luckily this is mostly figured out and the production version will go together a bit quicker.
I’m totally in love with this thing. Naturally. I’ve poured a ton of time and energy into it so it would be hard not to be in love with it, but the system as a whole really is fantastic and I’m very happy with it beyond time spent. Aside from a few bugs, all of which have can be side-stepped at present, the interface and operability are spot on. It’s actually very usable. I sort of knew this in advance because that’s how I designed it to be, but working with the final product is always validating. I’ve peppered previous posts with schematics and CAD files, so this post is where everything comes together and the prototype device is the results. I snapped shots after the major steps. By the way, both the PCB and the aluminum chassis are beautiful. Front Panel Express and ExpressPCB do great work. Having your designs fabricated and in-hand is thrilling after looking at them for so many months in CAD. Not a single complaint about either fabricator. I highly recommend both companies. Blah blah blah, let’s go!
The first step is always a general fitment test and figuring out the routing plan. I’m happy to say that obsessive checking and rechecking during design paid off because everything lined up. That’s literally hundreds of holes, edges, insets, mounts, and routes that needed to work together. None of these things are standardized; I had to place and coordinate each and every one. It can drive you mad. It can drive you mad to the point of checking, rechecking, and devising systems of checks to run through every time a part or placement is moved even a fraction of a millimeter. There, I said my bit. With the power supply and the main PCB in place, the first bit of routing to take care of was the line-level power route from the power input connector through the PCB, the fuse holder, and final termination at the power supply. The line-level conductors get special attention and double insulation on all contacts, joints, and terminations. The switching power supply that I used is worldwide ready and therefore the device will work anywhere automatically from 100 to 250 VAC 50 to 60 Hz. It will even run on remote DC power in most cases. See component specs for details.
The wiring above is the extent of the internal line-voltage section and everything that comes later is 12vdc. The next phase was PCB assembly. This is always a lot of fun, especially when it’s your own PCB. I tend to use very high quality parts on projects like this, so check them out if you’re a spotter. The output section is clearly marked by the high speed Crydom SSR‘s. The warm water bath was to remove the 331 flux residue before placing non-washable parts with a no-clean flux. During assembly I found a major hardware bug and had to bypass it using a jumper and by *gasp* cutting a trace. I’m not going to show that, it makes me way too sad. Needless to say, revision 6 of the board was born that evening.
With the main board assembled, cleaned, and tested it was the right time to tackle the front panel. I was trying to put this off but I had to see where the board harnesses were going to need to be coming from before I rooted them to the board. The front panel is a mass of industrial pushbuttons and LED indicators that looks great from the front but looks like a nightmare from the back. A huge mess of panel spaghetti. A whole days worth of wire harnessing and disconnect crimping took care of it as well as the mating harnesses which will connect directly to the main board. That’s over 150 Micro-Fit pin crimps in one sitting which equals a lot of pain. Molex Micro-Fit disconnects are wonderful, however, and really made it possible to have disconnects on all harnesses in such a tight space. You’ll see just how tight the space is as the build moves forward. If you’re curious, there are seventy-eight wires between the front panel and the main board.
With the front panel harnessed, the main board needed to be harnessed as well. This was a huge job and it included mounting and wiring the processor sub-board. This is where the device got its brain, so to speak. Between the main board and the processor board are 32-bits of digital I/O as well as digital grounds and the 5v USB power to the 5v section of the main board. Except for that and the very small line-voltage switching section, the majority of the main board is at 12v, see the schematics for details. Lots of time was spent here tinning the leads, installing boots, and generally doing it the right way.
Still to go from the main board are the power harness and the input and output harnesses. But this was enough to clamp on a power supply and boot the system. First try, total success and all lines reported exactly as they should. Can’t beat that. Back to the Molex crimping tools to build the two rather sizable input and output harness pairs, solder and secure the input and output ports, and root the main board power harness. And also the beeper. The four chrome input ports in the picture below, on the top panel with the orange, yellow, and white wires, are mirrored by six more for outputs on the bottom panel – and each wire was hand soldered, three for each input and four for each output, then insulated…these bits are where much of the time goes but this never comes across in the snapshots. Every wire to and from the main board, also individually soldered. Takes a lot of time. A lot of detailed work here. A lot of detailed work. If I don’t mention it here, I’d never get credit for it. Let’s keep going!
That’s one completed system right there, it just needs to be assembled. Now this is an important point in the build because up to this point I had no real idea whether this thing would actually fit together physically. It is hard to convey the space utilization factor that has to happen here by showing it all splayed out and unfolded. Worse, there is no way to show the assembled internals. This is by far the lowest spatial tolerance in any system I have ever worked on or designed. I was nervous. Everything was engineered mathematically to fit prior to having any physical parts to measure. Here’s the final assembly sequence and the very rewarding culmination of about thirty hours of very hard work on top of a years worth of research and design.
Even though it’s very tight in there, nothing is bunched, smashed, binding, or under any pressure. All of the harnesses and solder joints were made to withstand heavy shock and overall the device is designed to heavy-duty specs, aerospace specs in some sections. Lastly, the side profiles mount and the entire thing is *gasp* *finally* complete. I remember laying the first trace on the first schematic with only a vague idea of what I wanted -> FFWD -> a finished, working prototype. Huge steps, feeling proud, happy times. It isn’t over yet. Bugs to resolve, new features to implement, software to write, final version to build yet.
Here’s the first power-up stack: USB connection passed, power supply to board passed, boot passed, connect, link, click, beep, ready. After some harrowing systems tests involving mis-wired diagnostics cables (updated the design pinouts, forgot the update the test cables) and backwards meter probes…long, embarrassing story…I verified that the entire system works and all user points (buttons, indicators, and pinouts) are spot on. That felt really good. What didn’t feel good was a major hardware design flaw that turned up and rendered the output safe-mode unusable. This is not a build or tolerance issue, it is a design issue that I overlooked and it has to do with LED’s and leakage current. The result is that the outputs don’t shut down properly in safe mode with the ENABLE OUTPUTS key locked off. No big deal because this is the prototype and it was built to find these kinds of issues – still it was a bit hard to take. Otherwise, the thing operates perfectly with the outputs enabled and I have started to work on the front end with this hardware to program against, which brings some really exciting news about visual logic programming and some sexy software from DSP Robotics. More on that soon.
I’m hard at work on the final hardware which will include a very heavy PCB revision and a totally new output section design, some minor chassis updates and changes, and some really cool extra features such as a near-zero latency direct trigger mode for high-speed work, and more. The version built above was frozen several months ago and I have continued updating and adding to the design. But, basically, the device will look and feel like the prototype show above. That’s my sequencer. There it is.
I’ve also started testing sensors with the inputs and they are working 100%. I designed this thing to seamlessly interface with both professional photographic equipment and industrial control sensors. I have tested and verified perfect triggering with reflective IR beam triggers, IR through-beam triggers, capacitive sensors, inductive sensors, and several limit switch units. It triggers on time every time. I cannot phase it, trick it, or even outpace it. Super stable, super fast, super reliable at the inputs. The outputs are equally stable and I have verified flawless compatibility with Profoto generators, Profoto monos, Profoto Air radios, PocketWizards, Nikon DLRS, and more. The Crydom SSR’s are absolutely solid.
On top of all of that, I managed to leap from my desk after my phone in the other room and drag the unit onto the concrete floor where it bounced and rattled and generally made horrible impacting noises until it settled. I retested everything and can happily report that there was zero internal damage. Huge scuff on the upper right corner, but everything works. It’s tough! It ought to be.
Right now, beside me, it is up and running a fully implemented virtual wiring schema via FlowStone. FlowStone will allow anyone to design trigger sequences visually using custom on-screen components that control the physical device in real-time. If you want trigger input 1 to echo to output C, simply drag a wire between them and the hardware is configured the second you let go of the mouse. Much more on the software side coming up.
One step closer to a production unit.
Here’s a fun post! Say, let’s build something cool. I’m going to detail the shutter trigger monitor/profiler that I built this week and I’m including the schematic and parts list in case you want to experiment or build your own. Just keep in mind that this device requires an oscilloscope for full functionality, or at the very least, a pulse width counter. Also keep in mind that I am not responsible for your actions and that includes plugging things you’ve made into your expensive cameras – I refer you to the disclaimer at the end of this article for clarification. Right then, this is an offshoot of my router/sequencer project, but also a handy tool in its own right.
Camera shutters are mechanical/electromechanical devices that are prone to drift and corrosion. It’s great to be able to peek at the timings and trigger contact profiles in order to diagnose and evaluate their performance. This goes from handy to critical if you have applications that depend on the accuracy and consistency of, say, the leading edges of your shutter contact pulses. This is my situation and that’s primarily why I built this tool – but it’s a useful tool for general photography and camera repair as well. From a development point of view, this device acts as an adapter for my ScopeMeter, which I consider to be the handiest tool ever, that allows me to examine the electrical (and later, optical) performance of my shutters, etc.
This first design (Mark I) features three shutter ports, one for each of the three types of PC cable common in my kit: 1/4″ (shutter-to-generator), 3.5mm (shutter-to-radio), 2.5mm (shutter-to-back). This is purely convenience, however do note that the profiler can, with modification, act transparently and pass-through triggers to generators, digital backs, or whatever else you might connect to your shutter – this is planned for the next version (Mark II). Right now, let’s walk through the first version of the device.
The unit automatically powers on when plugs are inserted into the input jacks. When the inputs are empty, the batteries are completely open and will not drain. Power state is indicated via the green LED on the interface panel which also serves to indicate that the correct type of cable/plug is inserted and that the device is ready to go. The BNC port is for measurement output and it’s limited, protected, and designed to link to high and very-high impedance measuring devices such as oscilloscopes, DMM’s and counters. The output state is handily indicated by the yellow LED which turns on when the output is high and remains off when the output is low; it’s included for quick, on-the-fly connection checks and chain debugging without a scope attached. Leaving the profiler attached to a scope or other measuring device will not drain the batteries as long as none of the inputs are connected.
Connection to a shutter can be via any shutter cable that sports a 1/4″, 3.5mm, or 2.5mm TS connector. Only two-conductor (mono) plugs are supported, three-conductor (stereo) types will be ignored as long as the ring and sleeve are not common – in that case the profiler will not turn on. Any shutter with a contact type trigger output can be profiled and monitored as long as a proper cable exists or can be made. Connection to the scope through the BNC port should be made via a shielded RF cable, 50 or 75 Ohms. Noise floor is not a problem for this application so cheap cables are fine but higher quality cables will always make your life work out a little bit better.
All together, the device is compact, rugged, and easily stowed in my grip kit, ScopeMeter case, or even my pocket. I’m not actually going to carry it around in my pocket, but it would fit easily! So let’s hook it up to my ScopeMeter and have a look. As shown above, we’re into channel A with nothing in, nothing out.
Once connected to a shutter, the device powers on and remains ready to send trigger measurements to the scope. In this case I’m using my on-camera trigger cable for a Leaf back which is plugged into the 2.5mm input on the profiler. All three inputs are electrically parallel and do exactly the same thing.
I’m ready to go; now to setup the scope. I should point out that I’m testing the mechanical Copal 0 leaf shutter on my Schneider Apo-Digitar M 120mm here; this could also be any electronic shutter, SLR body, medium format lens – again, any shutter or camera with a switching trigger. It could also be connected via radio; the profiler can be used to examine radio delays and timing as well. I can also use it to look at the trigger output of an electronic technical shutter, a DSLR, or a digital back. Anyway, once connected I set my scope to fit a 3VDC peak and scale the display to the anticipated shutter speed – in this case I am starting at 1/125 sec. My Fluke 124 has the cool cursor feature, so I’ve set the cursors to delineate a perfect 1/125 sec. pulse width, which is 1000 / 125 = 8ms. You can also see that I’ve set the trigger to wait at 1.5VDC, or roughly half of the ~3VDC max output of the profiler. And so the scope waits happily until the profiler sends it a shutter pulse to chew over. For convenience I’m running my scope on-trigger instead of single-shot so that I don’t have to reset the hold each time I want to read the shutter – I can just click away and always expect the latest reading to be displayed. Either trigger mode will work just fine.
A closed shutter trigger (open shutter) means high output which is indicated by the yellow LED. Above I have the shutter locked open to take the picture, but pulses as short as 1/400 sec. can be seen and verified on the LED indicator. You can see in the picture that the scope is reading a steady ~2.8VDC with the output of the profiler in the high state. This peak reading will drop as the batteries wear, but timing performance will not be affected. So let’s look at an actual reading for the 1/125 sec. shutter speed setting on this Copal o.
(*click*) There we go. Instantly I can see that the trigger contacts close cleanly. I can also see that the trigger opens before the expected 8ms has elapsed. This is due to a combination of shutter mechanics and probably a slightly fast shutter. Note that any pre-delay is not recorded because the scope is triggering off of the shutter contacts, so presumably the shutter has opened fully before the initial trigger and will finish closing after the contacts break open. In order to get the actual photo-time of the shutter being tested for comparison I would need to use an optical sensor – this will be covered in Part II. For detailed analysis, I can upload any of the captures into FlukeView.
Here I can look closely at the rising edge characteristics and determine how my sequencer inputs will trigger from this shutter. And after looking at a few shutters I’ll have a better understanding of how to develop the input buffer sensitivity. Okay, but this is really unnecessary for most applications. I would like to point out the glitch that is seen just after the peak settles – this is probably due to cable capacitance or some other electrical aberration and it is seen on every shutter I’ve tested. It would be fun to track it down, but honestly, who cares. I’m hooked up, so let’s look at a few other shutter speeds while we’re at it.
(*reeclick*) (*reeeeeeeeeeeeeeeeclick*) These are readings for 1/8 sec and 1 sec shutter speeds on the same shutter. In each case I can see a crisp leading edge and constant output throughout the pulse. I have also verified perfect consistency over multiple actuations, and that’s exactly what I’m looking for. This shutter is electrically healthy and it will be perfectly compatible with my sequencer trigger inputs. I will cover more in-depth shutter performance testing once the optical section is completed – at that point I will be able to record the actual photographic performance and also see where in the shutter cycle the trigger is switching.
BIT OF A WARNING! The schematic above is updated from the wiring shown in the pictures. It has been modified so that the shutter inputs are tip-positive. The pictures in this post show wiring for tip-negative. Not a big deal at all; the reason is to provide broader compatibility with transistor switching in electronic devices. Build from the schematic, not the pictures. Also, I do not advise connecting this circuit as a pass-through to other devices. Wait for the second version which will feature a safe opto-isolated pass-through.
Moving on, and as promised, the schematic is given above. The circuit is basically a DC power supply working against a small load balance with a standard flyback and a series protection diode guarding the output which is designed for very-high impedance measuring tools. Noise can be a problem when reading peaks. The load resistor (R3) fills two shoes: sinking the scope input when the output is low and acting as a stabilizer when the output is high. The shunt diode (D3) is there to protect sensitive transistor logic on triggers such as digital backs, DLSR’s, and radio transceivers. The protection diode (D4) is provided as a matter of course to protect everything from wayward output connections. I am using stereo TRS jacks to control the power via the plug sleeves.
As to the power supply, I like the convenience of 3V power from two AA batteries, but this could easily be a 9V battery with adjustment to the resistor values. I know that 3V is safe for all modern shutter devices that I use as it is well below the standard sensing voltage. A Profoto D4 generator, for instance, listens with a > 10V potential.
So let’s open the hood and take a quick peek.
The Hammond enclosure that I am using is perfect for this application. The top panel is removable and easily machined with a drill press to take the connectors and LED’s. I’ve tightened all the nuts snug and set them off with a bit of Loctite to keep them from changing their minds.
What you see is mostly interconnect, with all of the business happening in the diode/resistor group soldered to the output jack. Very easy stuff. Solder cleanly and solidly and protect component leads with heat shrink for durability. Solder flux should be removed. In this case I’ve used Kester 331 organic core, so a warm water rinse took care of that. Keep water out of the 2.5mm jack if you do this and dry completely with warm air before setting the heat shrink and installing into the enclosure. A no-clean solder/flux could be used and the rinse could be avoided, but that’s no fun.
A nice fit with room for the future. Not shown are the two open-cell foam sheets that slip below and above the circuit in order to hold everything secure and provide plenty of shock protection. Expect a much shorter service life if everything is left to flop around.
Finally, here is a parts list for Mouser Electronics – the exact parts you see above, in fact. If you do decide to build one of these or experiment with shutter measurements, please share back. Lots of room for improvement here and, like I mentioned, stay ready for Mark II with simultaneous optical measurement, a safe pass-through, and more.
|1||546-1553BYLBKBAT||Enclosures, Boxes, & Cases 4.62 x 3.11 x 0.95 HAND HELD|
|1||523-115101-06-24.00||RF Cable Assemblies BNC St Plug-BNC St Plug 8218 24 in.|
|1||161-7000-EX||J3||Phone Connectors 2.5MM STEREO|
|1||161-MJ355W-EX||J2||Phone Connectors PHONE 3.5MM STEREO|
|1||502-112BX||J1||Phone Connectors 3C ENCLOSED 1/4|
|1||571-5227169-7||J4||RF Connectors BULKHEAD SOLDER JACK|
|2||78-1N4148||D3-4||Diodes (General Purpose, Power, Switching) 100V Io/150mA T/R|
|2||71-RN55D-F-150/R||R1-2||Metal Film Resistors – Through Hole 1/8watt 150ohms 1% 100ppm|
|1||71-RN55D-F-5.6K||R3||Metal Film Resistors – Through Hole 1/8watt 5.6Kohms 1% 100ppm|
|1||645-558-1301-007F||D1||LED Panel Mount Indicators GREEN DIFFUSED 14in WL LOW CURRENT|
|1||645-558-1201-007F||D2||LED Panel Mount Indicators YELLOW DIFFUSED 14in WL LOW CURRENT|
|(also)||24 AWG stranded hookup wire, solder, various heat shrink tubing|
As always, thanks for reading and happy building. Remember to share a link to this post when you can, it sure helps me out! Also, make sure to check out some of my recent posts for some pretty sweet images, projects, and builds. Cheers!
If you decide to build the device that I outline herein, that’s great, but you do so at your own risk. I cannot be held responsible for any damage to yourself or to your equipment that may result from the use or misuse of the electrical equipment that I describe in this article. I advise you to consult a professional regarding the specific equipment to which you intend to connect any device that you make.
Sit down; I’m embarking on a huge geek-fest right here. My girlfriend doesn’t know how to respond and, frankly, she would rather watch ice melt. I’m going to try to make this understandable, though, so please join me and send me feedback if you’re so inclined. On the other hand, I’m not one to blather on and pad everything; I’d rather just get into it.
I started designing a sequencing system about a year ago but became involved in too many other projects to finalize it. Now I’m back into it. My goal is to design a digital sequencer that is universal enough to use on any set and modular enough to handle just about any production. A sequencer is an electronic interface that translates trigger events (inputs) into controlled action events (outputs) with configurable timing, repetition, and routing. In the studio you would use one to trigger all sorts of things, from the camera shutter to the strobes, from liquid pumps to air cylinders. Anything that is electronically controllable can be connected to a sequencer to become timed, action dependant, and repeatable. To be minimal: a sequencer is a device that controls other devices in a programmable manner based on sensor or button signals.
My design is both a sequencer and a router, and it is comprised of an external hardware interface and software. Here are the basics: four programmable manual trigger inputs and four external trigger inputs, for a total of eight trigger inputs; six programmable outputs; USB connectivity; safety lockout; manual clear input; and what I’m calling dyna-power: three power modes offered via combinations of the three-pins at each input and output port. All inputs and outputs are fully programmable on any number of sequence busses. I will explain these things as I come to them.
Basically, we will take any number of trigger inputs signals and route them to fire any number of output signals, with programmable delay, period, and repetition. The hardware interface features four manual pushbuttons which can be routed to do anything that a trigger signal can do. Here’s an example: if I have my camera shutter on output A, my generator on output B, and a liquid valve on-set on output C, I might design a sequence which would wait for trigger 1 (a pushbutton) and then open-and-hold output A (shutter), open-and-hold output C (valve), wait 500 milliseconds, pulse output B (generator), and finally close output A (shutter) and output C (valve) in order to photograph a perfect pour. The major benefit is that this entire sequence would fine-tunable and repeatable.
I mentioned unlimited sequence busses. The above example would run on one bus; a bus being any chain of inputs and outputs connected logically. Because there are still 7 triggers and 3 outputs free in the above example, they can be used on other busses and provide sequencing for completely independent event chains. On top of that, triggers can be used across multiple busses, and multiple busses can activate the same outputs. I said it was fully modular. And, I didn’t come up with this overnight, by the way; I’ve been working on this for months.
There are a ton of other neat bits that I can’t wait to share, but I’ll do that in future posts. For now I want to share my progress on the hardware interface. Because the hardware is where it’s at.
The entire system is based on the Phidgets 1012 interface from Phidgets, Inc. This is a digital IO logic level interface with onboard USB and a fairly low-level C++ library on the computer to control it. The IO lines on the board are nothing more than individually programmable switches that either control or sense a single logic bit. In order to turn them into a working sequencer interface, I have designed a secondary controller interface which is the actual hardware interface that humans interact with on the outside of the interface box. Here is my current revision. (As always, click through to Flickr for a larger version.)
And here is the corresponding PCB for the above schematic, which is ready to mount the 1012 and connect all interconnects, pushbuttons, indicators, and switches mounted to the chassis. I have worked this PCB design over and over to make it as compact as possible while providing the designed current load for the provider power feature (more on that later).
I can also share the actual panel layout which will give some idea of the human interface. The chassis will be based on an industrial quality aluminum enclosure, fully weather (and liquid) sealed, and safety compliant for harsh environments. The latter is just because I’m a huge design geek, and why not. It is also so that I don’t electrocute assistants and the like. Here’s the latest panel layout.
I am sharing this project for three reasons: it’s cool, I want to blag on about how I can design and build electronics, and I want to show other photographers how I handle this problem in my studio. There isn’t a market for this sort of thing, really. You sort of need to roll your own. This is my own. I’m finalizing the design and sourcing parts right now. If you’ve actually read this thing with any interest you are obviously elite. Let me know if you have any questions or suggestions – I’d love to hear any input. Cheers!
More updates -
I finally have IP telephone service installed and working, thanks to phone.com. For those who don’t know, IP telephone service steps over all of the oldskool telephony, PBX, and even POTS lines by delivering super high-quality voice service over your IP network, which in my case is Comcast cable internet. My Polycom simply plugs into my studio router and it’s good to go. My service plan is hugely versatile with custom caller menus, scheduling, conditional forwards, and scalable lines, extensions, and virtual extensions. I can add local or even toll-free numbers and route them wherever I please. Awesome. And all of this for much less than a Comcast business-class digital voice line. Also, my phone numbers are now completely unbound from any physical address – if I move my studio or office I just unplug and replug at the new location; calls will forward to my mobile automatically in the meantime. The phone itself is tied to my Outlook via InGenius Connector and my service is managed online with instant changes and reroutes. Affordable. Cheap, even. Don’t worry, I thoroughly dusted my poor Linksys after seeing the picture.
I’ve just wrapped up a small countertop set build for a few shots that I want to do over the next week. This was really simple and it looks great. The base is 3/4″ OSB. I laid the 4″ tiles directly to it using standard tile adhesive, fine comb on the rough face of the board, with a raised edge for the back tiles and a dropped front for the edge pieces. I designed it to mate with my three-point leveling table, and it can be removed and stored easily. False walls can be mated seamlessly to the rear edge to provide variable environments. I’m starting with a generic white tile set. I can build others as I need them. Build time was about three hours plus an hour of grouting. Today it’s fully cured and ready to be sealed. The total cost was ~$40. Nice.
Finally, I have a preview of my new business cards. A few more tweaks, then off to the press. My new logo has already been present on the website for a few months. These new cards are a part of my new image which I’m slowly porting across the board. I’ve incorporated forward movement, stability, and adaptability into the text logo (can you see how?) whilst also making it modular (take away “photography” when representing myself). This standard was then forwarded into a larger graphic logo as an abstract representing still life photography and set construction. Everything is square, clean, and minimal.
Mail me one of your cards and I’ll mail you one of mine back.
This afternoon I finally took the time to build myself a leveling table for the studio. A perfectly level staging surface is required for beverage work and anything else that is gravity dependant. My friend Mark and I came up with a plan for one of these over coffee a few months ago; so all the bugs had been worked out and it was a pretty straight forward build. I did, however, move from 2×2′s to 2×3′s to add weight and stability.
Our leveling design solves three problems. First, it allows extremely precise leveling on both table axes. Second, it provides a variable table height over a 24″ range. Third, it completely prevents any bowing of the table top caused by straddling a pair of sawhorses. What used to take about twenty minutes with shims and careful placement now takes about a minute. Alternatively, it also provides controlled tilting for special effects.
Our table is very easy to build, just make sure to get the straightest lumber you can find. I used a miter saw and a corner jig to get perfect 45′s and I assembled each frame on a perfectly flat concrete surface. Both frames were fastened with a trim nailer first and then reinforced using angle brackets and heavy screws. The 3/4-inch all-thread segments are attached rigidly to the top frame via three sunken nuts and stabilized with nut and washer pairs. On the bottom frame, each segment floats through a hole where it is seized by nut and washer pairs above and below. To adjust each point, simply loosen the bottom nut and turn the upper nut until the height is correct, then retighten the bottom nut to keep it there. Standard all-thread is perfectly fine for extremely precise control. Insert this thing between your sawhorses and your regular table top and you are good to go.
Enjoy your weekend!