Custom Desk – Monitor Lift Mechanism

I got the idea for the monitor lift from an example online using all-thread as lead screws to drive a platform. Essentially I’m just replicating this idea but with a few tweaks that take advantage of having the lathe to make it better/stronger, easier to build, and to take advantage of spare parts I already had.

First I cut the all-thread rod to length and then I turned down one end of each to fit the inside diameter of some spare bearings. I left an extra bit on the end and turned it down to fit the inside diameter of a timing belt drive sprocket – this was later replaced with a chain sprocket due to slipping.  I repeated the same on the top side of each rod (without the extra bit for the drive sprocket) and then I cut some metal brackets to hold the outer bearings. I then cut a small platform and attached two nuts to it that would connect it to the threaded rods.

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These parts were all assembled into the desk; a few small shims were needed to get the rods exactly parallel. I then connected the threaded rods together with a small #25 chain drive. To power the lift I tried a few different test motors and eventually settled on the guts from a small/cheap electric screwdriver – this provided enough torque while not requiring a huge power supply. It could be a bit faster and I need to add some sound damping, but it’s working very well for an initial attempt.

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I also made some mounting plates to adapt the monitors to a fixed mounting since the regular bases were too wide. The monitors were then mounted to a 2×4 that acts as a spacer and also adds strength to the platform. Once the tabletop is in place the 2×4 and the rest of the mechanism will not be visible since the monitors will rise so that their bases are just flush with the top – I’ll likely add a trim piece to block this off. The monitors also drop low enough that the table top will clear with no problems.

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The last step was adding limit switches and rewiring – moving the toggle switch up runs the lift up until the positive switch is tripped, and moving the switch down runs the lift down until the lower limit switch is tripped.

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Next up will be making the tabletop…

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Prop Straightening

Continuing with the home office/study/library build, I found some decoration via a damaged airplane propeller. I was able to straighten it out using the press and some 2×4 blocking. The aluminum is springy so the key to getting it flat is to bend a bit past flat, just enough so that when it springs back it’s straight.

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There was a possibility that the amount of bending needed would create cracks. Based on prior experience with aluminum, I would expect for the paint to flake and for the surface underneath to turn white just before cracks occurred and I was looking out for this. If cracking had started, the plan was to heat the area with a torch until it was annealed, then continue bending – this would also have required repainting, so I’m glad it wasn’t needed.

For mounting it to the wall I cut a circle of 3/4″ plywood on the bandsaw. The circle is just small enough to fit into the prop hub, but too big to go through the smaller hole of the inner hub. Long cabinet screws then secure the plywood to a stud, sandwiching the prop in place. I plan to make another circle, paint black, and fit it into the hub to cover the structural piece.

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Piano Automation Begins

This weekend I designed and began fabrication of the parts needed for adapting the solenoid valves to the piano’s tracker bar. This adapter will consist of two 3/8″ aluminum plates. The top plate will have holes to accept the solenoid valves, and the bottom plate will have holes to interface with the piano’s tracker bar. Grooves will be machined into the bottom plate to create airs channel between the tracker bar holes and the solenoid valves above. The two plate will then be sealed together, covering the grooves; a similar construction technique as some carburetors. As long as the grooves are carefully routed, each valve should connect to exactly 1 tracker bar hole.

I cut the 3/8″x6″ plate on the band saw and then milled to final length. I used an edge finder to locate the plate edges, and then used the mill’s digital readout to position above each row/hole. For each row I took 2 passes, first spot drilling with a center drill and then drilling to size with a twist drill. 88 * 2 plates * 2 passes = 352 cycles of positioning the X axis and drilling a hole. Once all the holes were drilled I sanded sides to remove burrs from the holes and scratches from the rough plate.

Next I installed and wired the solenoid valves in the top plate. The solenoid valves are an exact fit to the hole, but I added a bit of CA glue to ensure they stay in place. Wiring consists of scrap Ethernet cord that’s been stripped back; Every ~7 solenoids each share a common wire to reduce wiring, but it’s still ~100wires.

I’m happy with the results so far; this is by far the most precise thing I’ve made on the mill and everything is lining up perfectly. The next step will be to 3D model the grooves and convert these to paths to run on the CNC router. I’ve done some aluminum milling with it previously so it should work out OK, especially since it’s just cutting the shallow grooves – I wouldn’t have trusted the router to drill the holes as well as the mill did.

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Window Crank Adapter

It’s not particularly hard to use a window crank, but multiplied by several windows it does take a little bit more time than it could.  With this in mind I created an adapter for a cordless drill to more quickly open/close windows, particularly as it’s starting to cool down some and we’re using the windows more.

Construction was relatively straight forward, it’s just a bit of aluminum turned to size and with a hole drilled with the same size as the OD of the splines on the window crank mechanism. The only tricky part was creating the splines since this is the first time I’ve attempted it. The lathe has a built-in index plate that allowed the adapter to be positioned in the 12 evenly divided positions required; once it was in each position I used a small lathe tool to broach a slot, moving the carriage back and forth with the lathe off while slowly raising the tool. I then turned a bit of steel rod to size and pressed it into the back of the adapter.

Overall it turned out OK – the splines aren’t the greatest due to the tool not being very rigid, but it’s plenty good enough for it to engage with the window and hold solidly.

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Kubota F2000 Snow Plow

We don’t get much snow here, but when we do it takes a lot of shoveling to get out to the road. If conditions are just right we can be stuck for several days waiting for it all to melt. As a result I’ve had a mower/atv sized plow on my watch list since last winter. Recently a new open-box plow popped up that, after factoring in their free shipping, I got for basically scrap value or less. I think the reason for the low price was that it had originally been part of a kit, but all the mounting parts were missing.  For my purposes that’s OK though – no one makes a kit specific to the F2000 anyways, so I was always going to need to fabricate the mounting parts myself.

Making the mounting bar just consisted of cutting some 1″x2″ tube to length, squaring off the cuts on the mill, drilling holes for the pins, and then welding everything together. From there the plow’s base just clamped between the mounting bar and another section of tube.I made the clamping bolts fit just inside the plow base’s big hole so the plow can be rotated by loosening the bolts. Since the push bar connects to the standard implement mounting points, the plow can be raised/lowered the same way as the mower deck. I also needed to make some stepped bushings on the lathe to fit the plow base to the plow.

Kubota doesn’t list a tow/plow rating for the F2000, but it’s 4WD with a 3 cylinder diesel and built exactly the same as a ‘normal’ compact tractor, the only difference is that its seating position is spun around 180deg. For occasional plow usage I don’t foresee any issues. I may need to tie into the plow base’s rear holes for stability and to prevent unwanted rotation, but I’ll try it out first to see if this is necessary.

As part of the plow installation project I also went through the mower’s electrics and replaced a lot of corroded connectors with solder/heatshrink splices. It turns out the glow plugs hadn’t been working all along. With the glow plugs now working it starts a lot faster and in winter this will likely be a necessity to start at all.

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Hacking the Player Piano – Part 1

 

It was only a matter of time before this happened – the player piano (original post) is a real workout to play manually. Since it works on vacuum, I had set aside the motor from an old vacuum cleaner for potential use in powering the piano. Tonight I built a small box to contain the vacuum motor and connect it to the piano. The box is made from MDF, partly because I had scrap that needed to be used, and partly because it’s very heavy & sound absorbing. I made the big fitting by cutting/milling a square from scrap, I then bored a hole in it on the lathe and welded it to a scrap of pipe.

One very large hose goes to the manifold powering all the key bellows, and another smaller hose powers the vacuum motor for the tracker/scroll mechanism. I didn’t notice the smaller connection at first, so I had to go back and tap a fitting into the connection for the large hose; there’s still enough room for both to connect though.

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Overall it seems to work great, this effort was definitely a quick proof-of-concept though and I’ll need to go back and fix/test a few things:

#1 – Motor controller to slow down the vacuum motor. Currently it has way more vacuum than is actually needed and slowing down should reduce noise from the motor.

#2 – Ensure cooling is OK. Especially after slowing the motor down I need to test that air flow is good enough to keep the motor consistently cool.

#3 – Mount in piano base and complete further noise insulation.

#4 – Tee hoses (and potentially add check valves) so that manual operation still works.

Beyond that I do have plans to eventually (could be tomorrow, could be in 5yrs) automate the player mechanism using some small pneumatic solenoids I found on ebay. These would tee off of each line from the tracker bar and when they open it would simulate a hole in the paper passing by. With this it would then be computer controlled and able to play anything. By default these are off/closed, so the paper mechanism would still work fine, in computer-controlled mode I’d just need to block off the tracker bar holes with some tape.

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Kubota F2000 Lift Cylinder Re-Seal

Tonight I rebuilt a leaking hydraulic cylinder on the mower. The leak was coming from the scraper/seal that seals the rod to the end of the cylinder. Unfortunately since the end of the rod is larger than the seal, the cylinder has to be disassembled to replace it. The process went as follows:

#1 – Remove cylinder from mower.

#2 – Remove the internal cir-clip that holds the cylinder end inside the cylinder bore. This was extremely fiddly and took 20min or so with dental picks and small screwdrivers to get the end of the clip pulled out.

#3 – Remove the cylinder end and piston/rod from the cylinder bore. The cylinder end’s O-ring catches on the cylinder’s cir-clip groove, so while it moves freely to a position that’s ‘almost’ out of the bore the last bit of movement requires clamping the rod in place and persuading the cylinder downwards with a hammer.

#4 – With the piston/rod/end removed from the cylinder, the nut can be loosened and the piston removed. The piston is a press fit and requires a gear puller to remove and a hydraulic press to reinstall.

#5 – With the piston removed the cylinder end slides off of the rod and the scraper/seal can be replaced. The scraper has it’s own small cir-clip that’s much easier to remove.

#6 – Re-assembly is the opposite of assembly, while I was at it I also replaced the cylinder end O-Ring.

#7 – Reinstall

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After the rebuild the mower no longer has any hydraulic leaks; the last remaining leak is an engine oil leak that I’ll be tracking down next…

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Piano!

Christina has had an eye out for a piano for a while.  Interestingly the standard price for used pianos is ‘free, must be able to move’. With this in mind we were shopping on ease of moving – looking at the surroundings in the listing photos to determine where it likely was (i.e. garage vs inside) was almost as important as the piano itself. The right one popped up this week, so this weekend we took the trip to pick it up. I had a particular interest in this one also since it’s a player piano. Player pianos are one of the earliest (the earliest?) wide-spread programmable automated ‘machines’; it’s fascinating to see how these were designed to be built using mostly hand-made parts and to operate without electricity.

Moving: Pianos are the archetype of things that are difficult to move. The trick, as usual, is letting the equipment/physics do the work. At the pickup side it was already in a garage; after backing up near it I jacked the tongue of the trailer up so the ramp/bed formed an even & shallow slope. I was ready with the winch at this point, but because their driveway sloped away it actually rolled onto the trailer without needing it. To unload, I backed the trailer around the back of the house to the back door and then raised it up on jack stands until it was about even with the threshold. We then put a 4×4 timber across the bottom of door frame of a nearby interior door and used this as an anchor point to winch the piano inside with ratchet straps. Once it landed on the tile floor it was easy to push around.

Rebuild: As near as we can tell from the serial number the piano seems to have been built in 1920. It was also signed inside with a 1996 date, likely associated with a rebuild. The good news is that everything seems to be in place and after sealing a few vacuum leaks it was able to play automatically; It definitely had/has room for improvement though. I was able to make it sound noticeably cleaner by dialing in the correct ‘capstan’ height on the back of the keys. The next priority is getting the keys working more consistently; several of the keys (~40) were missing felt from their front hole. The front hole felt prevents the key from wobbling side-to-side. Several keys (~20) also had cracks where the back hole goes through the key. The back hole is where the key pivots, so these cracks allowed the keys to tilt side-to-side. Felt was added to the front holes and the cracked back hole parts were glued back in place; this resolved the loose key problems. For just a few keys (3) the cracked part is missing and I’ll need to create and glue in a repair piece. Once I’m finished rebuilding the keys I can then go through and set the key level and adjust the hammer action. Along the way I’ll also be coming up with an electric vacuum pump – pumping with the pedals is a work out!

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Security Lug Defeated

 

This week’s challenge was a flat tire; I switched to the spare relatively quickly and uneventfully except that when I was tightening the security lug bolt the security key slipped out a bit. When it slipped it broke a little chunk off of the security key and warped the security pattern on the lug bolt. I ordered a new key and lug right away but since I didn’t want to risk the warped lug bolt breaking the new key, I had to come up with some other way to remove it.

First I tried a broken lug extractor – these are cheap and readily available at the local car parts place. They’re basically a regular impact socket with a reverse thread on the inside rather than the usual hex pattern. The theory is that as you loosen the lug the socket’s threads bite into and turn the lug bolt. This actually would have worked great if it weren’t for a collar that’s integrated into the security bolt – the socket only bit into this collar and it spun on the lug bolt without turning the bolt body. It’s almost like they thought of this scenario when the security lug was designed…

Next I tried to cut some small grooves in the bolt head and deform the collar into these grooves so that the collar would be able to drive the bolt out. I think this was an OK idea, but since the collar was glass-hard steel it chipped instead of deforming.

Running out of options, I decided just to weld a nut to the security lug bolt and unbolt it. I had held off on this ‘nuclear option’ because there is a level of risk – the ground current could actually weld the bolt into the hub somewhat or damage bearings/electronics – I chose the ground clamp location carefully and also cleaned it carefully to avoid this. It was a messy weld (prioritizing not damaging the spare) but worked great. I think the heat from welding may also have helped by expanding the bolt and relieving some of the pressure against the spare.

With the lug bolt out the spare was swapped to the (now repaired) wheel and tire. Not sure how a dealer/mechanic would handle this scenario, but I’m guessing it means the welder has now paid for itself for at least the 3rd or 4th time.

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Dust Collection

This weekend I installed the shop dust collection system. The system consists of several parts:

Fan/Motor: I repurposed a portable dust collector fan I’ve had for a while that’s been underutilized (collecting dust, but not as intended). Space is limited in the mechanical room so since the fan won’t need easy access I mounted it high up above the air compressor near where the dust collector pipe enters the mechanical room.
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Pipes: 4″ PVC DWV pipes; there are a few branches leading to the different tools. I tried to keep the overall length as short as possible and the bend radius’s large.

Blast Gates: The blast gates control the air flow though the system by blocking off unused branches. I made these with 1/2″ plywood and 1/4″ hardboard. Circle cutouts were made on the lathe to match the pipe outside diameter exactly.
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Filter and Collection Bin: The portable dust collector came with a light canvas bag that restricted the air flow massively while still allowing fine particles to escape. To improve this I replaced the bag with a semi truck air filter mounted to a trash can. The theory is that air will exit the filter and larger dust/chips should fall into the trash can below. There are purpose-built dust collection filters available, but the costs are much higher for these and the semi truck filter has the same specs; different economies of scale. To mount the filter to the bin I made a plywood ring, for now they’re just taped together but I may add latches at some point. The design may need some tweaking; I’ll know more after it gets further use, but for now the airflow is excellent.
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Return Vent:  Having the collection bin in the mechanical room created a problem; the mechanical room is well sealed for noise reduction, so there was nowhere for the air exhausted from the filter to go. For heat/air to be retained in the shop, the exhaust air needed to return to the shop via a vent. Since I also wanted to keep the mechanical room noise level as low as possible this meant the vent needed to be sound proof. I built a sound proof vent by creating a 3ft long box and offsetting baffle plates inside of it. The sound has to reflect a dozen or more times off of the baffle plates; at each reflection it gets absorbed some by a fiberglass lining. The air, however, is able to snake around the baffles and find its way out. The inlet to this vent also points directly at the floor away from the sound sources. Somehow after adding this vent the mechanical room noise is actually noticeably quieter than when it was completely sealed. I think this may have had to do with the air pressure changes resonating in the previously sealed room, whereas now any fluctuations are equalized through the vent.
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Control: For now control of the system is via a remote control outlet (repurposed from controlling the vacuum at the old shop), at some point I may integrate some low voltage switches with the blast gates so the motor will turn on as soon as any gate is opened.

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