Piano Automation – Valve Manifold Complete
This weekend I had a chance to test the completed valve bank.
Testing revealed that some of the keys did not actuate with their corresponding valve open. On these keys when the valve (while turned ON/open) was removed from the manifold the key would strike immediately, pointing to lack of airflow through the valve as the cause. I can’t explain why this occurs on only some of the keys but the piano turns 100yrs old next year, so the inconsistency isn’t surprising. The piano could perhaps be adjusted to make these keys work the same as the rest, but I could more easily just provide more airflow via multiple valves per key – this is the approach I took. To connect multiple valves per key I created a few hollow standoffs that fit inside the valve holes in the manifold . The standoffs then have holes on their sides to allow connecting the extra valves on a 2nd layer above the rest. The end of the hole that was drilled to hollow the standoff was sealed with hot glue. Two valves solved the problem for most of the offending keys, but one extra special key required 4(!) valves in a ‘+’ configuration.
With the mechanical parts complete I’ve taken the first steps to construction of a raspberry-pi based controller that will use shift registers to power the solenoids. The raspberry pi and associated circuitry will be small enough to fit on the back of the valve manifold in the area where the paper roll would normally be. It has wireless connectivity and I plan to have it host a webpage where it can be controlled by phone/tablet. I’m bread boarding this first to prove the concept with one shift register, then once testing is complete I’ll create a circuit board to hold all 11.
Piano Automation Continued
Over the past week I finished the lower valve manifold plate. The lower plate connects the row of holes on the piano tracker bar to the valves on the top plate. Obviously it would have been nice to just put the valves directly over each hole, but since the valves are much wider than the hole pitch I had to instead design the manifold with the valves arranged in multiple rows. Each tracker bar hole is connected to the valve above via passages that are routed into the bottom plate. The path of each passage was chosen carefully to avoid connecting to other valves/passages and to avoid running into the bolt holes that connect the manifold halves – each valve should connect to exactly one tracker bar hole. I let the CNC router do this work; it was relatively slow going with a 1.5mm end mill in aluminum but it turned out OK.
After the passages were milled I created a gasket using wide tape. The tape covers and seals the top of the passages and a hole punched at each valve location allows each valve to connect to its passage. The tape has enough compression that any imperfections in the plates will be sealed once the plates are bolted together. I also added a lip/shelf to the back of the manifold to hold it in vertical alignment against the tracker bar.
With the manifold ready, I connected it to the piano and tried firing the outputs. Results were not good, there was some vague correlation between outputs being on and notes being played but something was wrong. I had originally assumed the air passed all the way through the valves but closer examination revealed that they actually pass air from their stem to ports near the base of the stem. Since I had the entire stem/base of the valve mounted inside the manifold there was nowhere for air to flow when the valve opened. I re-made the top plate with smaller holes and re-installed the valves with only the stem in the manifold.
Remaking the top plate solved the valve problem but there were many dead notes due to air leaks at the tracker bar. I experimented with several materials to seal the tracker bar to the manifold and ultimately landed on thick rubber outdoor electrical tape as the best performing, though many leaks remained. I found that the tracker bar was not very flat and I was able to carefully bend it back. This helped considerably but leaks still remained. I found that the force needed to push the manifold against the tracker bar for a good seal had the effect of bowing the tracker bar away from the manifold in the middle, so I added a thin aluminum lip to the shelf on the back of the manifold. The lip is just thin enough to fit between the tracker bar and the wood cover behind it and it allows the manifold to hook over the top of the tracker bar and more positively hold the bar along the entire length of the manifold with enough preload on the tape to seal. This essentially solved the leak problem.
Currently there are ~12-15 keys that I’m tracking down problems with, this started from ~20 and was reduced by working through electrical/alignment problems. On the remaining dead keys I’ve ruled out problems on the piano side, problems with the lower plate, and any electrical problems; so next step may be replacing the valves themselves. It’s possible that those keys need more airflow, which would require milling their passages deeper and/or modifying the valves; hopefully it doesn’t come to that. Once they’re all firing though then the mechanical work on this is basically done and I’ll be able to shift focus to the control system side.
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.
Saw Milling v2.0
A while back, in anticipation of more log milling, I made a jig for holding the chainsaw level along the length of the cut. This is basically a homemade version of an ‘Alaskan Sawmill’, with a few changes. Since I processed last winter’s log recently it made room for another in the drying area, so I finally had a chance to test out the jig this weekend. For the first cut a ladder is secured to the top of the log to establish a reference surface.
I opted on not tie the reference block into the end of the bar, since I have a limited bar length. Because of this, I also couldn’t make the reference block adjustable without introducing too much flex. Instead, I set it at the maximum board width I may need, and for all thinner boards I’ll add more wood to the block or log to shim it. This also gives me the ability to cut from both sides for a log that’s up to ~2x the bar length.
Altogether this test seemed to work great, the cut was extremely flat compared to the previous log that was cut free-hand. It was fairly slow-going though since I was using a standard chain; I have a ripping chain on order that should cut faster with the grain, I’ll install it before finishing this log.
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.
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.
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.
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.
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.
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.
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.
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.
Planer Cart
(I’ve had this built for a while now, but I’m catching up on documenting shop progress tonight)
A while back I got an old Delta ‘Portable’ power planer at a garage sale; it’s helped out in a few projects already so I thought it deserved it’s own spot in the shop design. The planer requires a fair amount of space for it’s infeed and outfeed to keep the material flat, however the planer isn’t used enough to justify keeping it out on the workbench permanently. I also wanted to avoid the need to lift it out of a cabinet, so with this in mind I came up with the cart below that integrates with the cabinets. The cart rolls on double-locking casters and has folding infeed/outfeed tables that align with the planer’s table when upright. I used ‘drop leaf’ style hinges/supports to allow the tables to lock in place.
The ‘dead’ space inside is currently holding the router and router bits; I may convert this to a drawer at some point. When the cart is stored it just looks like any ordinary cabinet door.
Cabinet Handles
Over the last few nights I’ve been working on handles for the cabinets. The handles are 4″ sections cut from 1.5″ aluminum angle. Before cutting to length I ripped ~1/2″ off of one side of the aluminum so the handles weren’t too wide. This was my first time cutting aluminum on the table saw, it was very quick and effective but also shot scalding hot aluminum chips in every direction and sounded like a Pterodactyl being fed through a wood chipper.
Since I may add/change cabinets in the future I wanted to make sure that I wasn’t locked into a particular brand/model of handle that could be discontinued, by making my own with standard materials this isn’t a problem and the cost was also kept to a bare minimum.
Once all the sections were cut to length I sanded the rough edges and drilled/countersunk holes on the drill press. I made a quick fixture with clamps and wood blocks to get the holes consistently located. To attach the handles to the cabinets I chiseled out a 1/8″ recess and then attached the handles flush with the door edges.
I’m undecided on whether these will keep their current ‘brushed’ looking finish or whether I’ll polish or paint them. I’ll decide that when the time comes to finish/paint the cabinets.
Sliding Doors
The shop floor plan allows for a large opening between the ‘far’ end of the shop and the auto repair/bus area. This will allow tools to be easily shared between both spaces; during a big auto project the repair bay can become an extension of the workshop. The opening is also big enough to bring in the front or rear of a vehicle if ever needed. When auto projects aren’t underway though I’d like to have doors cover this opening to prevent dust/mess from wood/metal project leaving the shop area and to save on shop heating/cooling costs.
The size of the opening presents a problem – swinging doors would have to swing ‘out’ of the shop to avoid hitting cabinets, and the large sweep would require moving anything parked on the garage side out of the way temporarily, kind of a hassle. To avoid this problem, sliding doors made the most sense.
The shop build project is being run with the materials cost set to minimum and the end-product quality set as high as is practical. This sounds unrealistic but is actually possible with the trade-off being time; it’s not a problem though since I count this as hobby time and there’s no particular deadline. The sliding doors are a great example of this – sliding doors and hardware are outrageously expensive compared to the raw materials cost. Building my own also gives me full control, in this case I wanted to avoid the farmhouse/barndoor/rustic look in favor of cleaner traditional/modern look. Over the last few weekends I’ve built the doors and tracks below, key points:
- Door frames from 2×6’s, planed down to standard 1 3/8″ door thickness
- Mortise and tenon joints connect frame pieces (tenons via table saw dado stack, mortises via router and chisel)
- Slide rail is two 3/16″ x 3″ x 10′ flat bar sections welded in the middle.
- Door bracket pins turned and threaded on lathe then welded to brackets.
- Aluminum rollers turned on the lathe, held to the brackets using standard 608 skate bearings.
- Brackets recessed into door frame and secured to the doors with studs welded to back side for a completely smooth front.
- 1/4″ Tempered glass sourced from local glass shop.
- Groove along bottom of door and small bottom bracket keep door located against the wall and limit inward overtravel.
- Roller to door top spacing and roller flange width prevent door from lifting/falling off rail.
There’s a good bit of finishing work still left, but I’m happy with the results so far.
