AMF Alcort Sunbird sailboat

My latest project is a 1979 Sunbird sailboat.  This picture is as purchased.  Astute observers will immediately notice a couple of major problems!   First, the mast is being carried in a very poorly supported and unstable manner.  The second is that the trailer is absurdly short for this boat.



I decided I wasn't going anywhere with this setup, so I concentrated my initial efforts on the trailer.  Step one was to lengthen the trailer.  I was able to add 24" to the frame, and 36" to the wooden bunks.  Since the Sunbird manual recommends 4 keel rollers, I added them, using brackets made from Unistrut.  They make sturdy brackets, and were much cheaper, especially since I had the Unistrut on hand.

An inspection of the trailer wiring revealed that nothing was worth salvaging, so I replaced everything and installed LED tail lights.  The lights I bought claimed to be submersible, but they were submersible in the same way an inverted cup is submersible.  There were openings in the bottom for the wires, and the lenses were sealed with simple foam gaskets.  I made them truly waterproof by sealing all the holes and seams with hot melt glue.

  Now to tackle the mast support problem.  My goal was to have something that is sturdy, easily removable, and lockable.  I also decided to add a center stop light to reduce the risk of getting rear ended in traffic.  In addition, the mast protrudes about 4 feet past the trailer lights, which is a bit too far.  By adding lights to the mast support, this distance is reduced to 2 feet.  The support is a bar of aluminum 1/2" x 1 1/2", and the mast holder is made from 1/8" aluminum. The support has pockets on the back side that the rudder hinges go into. Then a 5/16" rod drops into the top rudder hinge, locking to it securely.  When the mast is installed, the rod cannot be backed out.  The mast is secured with a padlock, securing everything in place.

The lights plug into a receptacle next to one of the trailer lights.  The lights are bright and hard to miss.

The boom block's plastic pulleys were degraded from 30 years of exposure to the elements.  Since I have a 3D printer, I decided to put it to use, and print my own replacement pulleys in ABS.

I began by milling of the head of the rivets holding the block together. I milled as little as possible off, for I plan on reusing the rivet.

I reassembled the block using stacks of washers to prevent the block from spreading now that the rivet's head is gone.  This works well, and below is the rebuilt block.

I practiced rigging it in my back yard. Note the mouse-eaten sails. 


















The Sunbird's maiden voyage was a success.  There are no leaks, and we didn't have any mishaps.  The Sunbird is a great boat.  Stable (for an un-ballasted boat) and easy to handle, she moves along nicely in gentle 5 knot winds.  A nice (and inexpensive!) way to spend a Sunday afternoon.

However, it is not very nice when the wind drops to zero!  The Sunbird took a surprising amount of effort to paddle in.  That experience made it clear that an auxiliary motor was essential.  The Sunbird manual recommends a long shaft motor, max 6 HP.   Unfortunately, long shafts are not common on the used market, and new motors are prohibitively expensive.  I found a 1970 6HP short shaft Evinrude in very good condition, so I bought it and then got to work designing a motor mount to enable me to use it.  This gave me the opportunity to solve a second problem.  Where to put the gas tank?  There isn't much room in the cockpit, especially when one is scrambling around adjusting the sails and switching sides to balance the boat.  Therefore, I designed a mount which both lowers the motor and holds a gas tank.  As a bonus, the motor is moved 10 inches off the stern, completely removing it from the cockpit area.  I made the mount from 1/8" aluminum sheet and 1" x 1 1/2" bar stock and bolted everything together with 47
 

10-32 stainless screws.   I wanted this mount to survive the worst possible conditions while protecting the gas tank and remaining securely attached to the boat and motor.  The mount can hold a 1 1/2 gallon tank, which is all I need.

I machined an aluminum cap with tubing fittings for the fuel and vent lines.  It is spill proof and impervious to water splashing in.

 These pictures are of the original concept.  I have since trimmed the top twice and raised the mount 3 inches.  The pictures above are of the original design while the picture below is of the second generation.

It is bolted to the boat with four  5/16" stainless bolts.  The upper part of the Sunbird's transom is reinforced with wood inside, making it plenty strong to support the motor in this fashion.  The 1970 Evinrude is a nice little motor.  It is extremely well made, and easy to start.  It is also remarkably quite at no-wake speeds, which is the condition that I will be primarily using it in.  At 6HP, it will be loafing most of the time, while a smaller engine would need to be run at higher throttle settings.  It is also not excessively heavy at around 45 pounds.

The motor moved the boat along nicely on my first open water test, going what I estimate was about 12 knots, and burning less than 1 gph. Full throttle was surprisingly quiet.  I was curious about the condition of the water pump when I returned home, and after dismantling, I found the pump housing to be badly corroded and the impeller worn.  Pumps housings, new or used, are expensive.  So, I decided to fix mine with a stainless steel liner.  By lucky coincidence, the inside diameter of the pump was nearly identical to the diameter of my scrapped Craftsman air compressor cylinders, which are stainless steel sleeves. I bored out the pump housing, and installed a section of the Craftsman cylinder as a liner.

Then I once again raised the motor mount to it's third, and final position.  Now the short shaft motor is mounted only 2 inches below the Sunbird's transom, and it is still plenty deep in the water.   It now clears the water when raised by 3 inches.

 Every sailing trip has made me aware of something that needs to be repaired or improved.  The latest is the rudder spring pin.  The hole in the rudder was greatly enlarged, so I made a pair of aluminum bushings to fit in the hole after I drilled it out to restore it to a round shape.
At right, the pin and bushings.  Note ugly hole in rudder.  Below right. Bushings on pin.  When installed in the rudder hole, the bushings meet in the middle.

Bottom:  Installed in rudder.  The larger diameter combined with the flanges should prevent the hole from distorting again.

 Another quick fix.  The bracket at the top of the mast was missing, and the previous owner simply tied the end of the boom cable to the mast.  I made one out of aluminum C channel.










 I quickly realized that raising the mast without assistance was a risky operation.  First, you are standing inside a boat with an uneven deck and obstructions like the boom pulley in the center of the deck.  Second, the boat is likely a bit unstable even though it is on a trailer.  Third, the mast is 20 feet tall, and you are at a huge disadvantage as  you are holding the mast only a few feet from it's bottom.  Lose your balance when you are halfway up and the mast can fall to the side, for the side stays are still slack, or it may fall back on you.  Once you have the mast fully upright, the fun is just beginning!  Now you have to maintain forward pressure on the mast while walking around the cabin and up to the bow to attach the fore stay.  Hopefully you have the fore stay in one hand, and it is not tangled up with the various ropes and rigging.  Now attach the fore stay to the bow fitting while not letting go of the mast.  Yes, it can be done, and has been done by many people for many years.  But it only takes one slip to lose control of the mast and probably break something. Even worse, you will be quite embarrassed if anybody was watching you at the time.   Rather than risk the embarrassment, I devised a safe and simple way to erect and lower the mast solo.  I attached a simple pulley to the bow fitting and then I tied the ends of the jib rope together.  I then tied my mast raising rope to the jib ropes and threaded it through the pulley.  Now I raised the mast in the conventional manner, but while taking slack out of the rope.  The mast is much more stable, with less of a tendency to fall to either side.  Once it is fully raised, simply wrap the rope around the cleats at the base of the mast, and the mast is secure.  You can now go up to the bow fitting at your leisure, without worrying about losing control of the mast.  I have also found it easier to tighten the fore stay since I can put tension on the rope while tightening the turnbuckle.  The pulley is not in the way of the jib, so I just leave it there and attach the jib to the next hole.  To lower the mast, simply reverse the process.  For me, the reduction of accident risk is well worth the few extra minutes it takes to attach and remove the rope.

This picture could have been taken in 1983.    A 100% vintage rig:   A 1983 Ford towing the 1979 Sunbird on a 1979 Dilly trailer.  Observant readers will notice that the sails and boom are removed.  A gusty crosswind was blowing across the ramp that day, so I removed the sails at the dock.

1920's era Athol Vise

I've received a few inquiries about my Athol vise, so I've made it a separate entry with additional pictures. What makes this vise unusual is the dog clutch in the handle that allows the handle to be repositioned by pulling straight out on the handle and rotating.

These teeth are rounded just enough to allow the clutch to slip under load. I removed the spring and tightened down on the nut to prevent it from disengaging.

A 14/20 screw holds the handle on the shaft

These teeth are also worn.

The spring went in here.  I removed it and made a sleeve to go in it's place to prevent the clutch from disengaging.

3 Years of Solar Hot Water Data

Here is some of the most comprehensive data on solar hot water performance you will find anywhere:  3 years of daily records for my 80 gallon Reynolds solar hot water system.  It has performed remarkably well, year round.  The number of days it did not run at all is surprisingly small and consistent:  53 days in 2009, 49 days in 2010 and 48 days in 2011. The number of days it reached 100% of capacity is 120 days in 2009, 181 days in 2010, and 190 days in 2011. The number of hours it ran is a little less consistent:  1990 hours in 2009,  1888 hours in 2010 and 1651 hours in 2011.  While it may seem odd that 2011 has both the fewest hours and the most 100% days, it is because the system needed to run less, as the storage tank was frequently still hot from the day before.  Unfortunately, I don't have an hour meter on the electric heating elements, or a water meter to measure actual use.  I estimate that we use between 30 and 40 gallons of hot water each day.  Since the system uses only 175 watts when running, it is using less than $50/year in electricity, while saving over $400.  The system has paid off the initial investment, and is now giving me a return in excess of 30%.  

         This is one form of renewable energy that is truly competitive with conventional sources.  Here are the reasons why:

            1:  The systems are uncomplicated.  Two panels with antifreeze circulating in them, a heat exchanger, a pair of small pumps, and a standard 80 electric hot water heater tank.

            2: They are efficient.  Hot water panels are approximately 40% -60% efficient vs.  14% for solar electric panels.

             3: The systems are reliable.  My panels, heat exchanger and pumps are all 28 years old, with plenty of life left in them.

            4:  Unlike solar or wind electric, the energy is easily stored for later use.  It usually takes 3 overcast days for my system to go cold.  In 2011, there were only 23 days where the system was below 90 degrees. Even 90 degrees provides a significant savings, as my electric heater does not have to heat 60 degree well water. Heating 90 degree water reduces my electric consumption by 30% vs. heating 60 degree water.

In 2009, the system made 63% of our hot water

It 2010, it made 77%

In 2011, a record 80%

Finally, some suggestions for those considering installing a system.  If your latitude is in the 40's, angle your panels to at least 45 degrees.  Why?  Because if you have them at a lower angle, they will overheat in the summer, and under-perform in the winter.  Ideally, the system is running through most of a hot summer day, which prevents the panels from overheating.  When the antifreeze is not circulating, the panels can easily reach 220 Fahrenheit, and the antifreeze will begin to break down and become acidic. Not good for the pipes.  An angle of 45 degrees or higher will reduce the amount of direct sun exposure in the summer, while still providing plenty of hot water.

The 45 degree angle helps in the winter, when the sun is low in the sky.  The panels will capture a good amount of winter sun.  Even in my worst winter, 2009, the system was making 40% of my hot water.  Another advantage is that snow readily slides off the panels.  I rarely lost more than a day due to snow coverage.  If it was a sunny day, I would often turn on the pumps manually to defrost the panels. It wasn't long before the snow slid off and the panels were capturing more energy than the defrost mode used.  This method worked with as much as 8 inches of snow on the panels.

I believe that for most people, evacuated tube collectors are unnecessary and simple flat panels are a better choice. Here my explanation why.

This is a picture of the panels on the day after a snowstorm that deposited about 12 cm of snow on the panels. It is 10:45 AM, and the outside temperature is -12c.  A small area of the panels was exposed by the wind, and that was enough to begin to warm the panels the panels to 38c. The pumps started up, and soon the entire system was at 38c.  That rapidly melted the remainder of the snow.  By 11:40, the panels were 80% clear, and the system temperature was now 57c.
 
These pictures also illustrate why I believe that solar panels should be installed at a minimum angle of 45 degrees in northern climates.  The snow readily slides off, and the panels are well positioned to capture the winter sun.  They produce more than enough hot water in the summer, even though the sun is then higher than 45 degrees.

In only 3 hours, the system had heated  300 liters of water from 23c to 43c, while the outside temperature never exceeded -10c, and the winds averaged 22kph. 

Unfortunately I have no comparable data on the performance of evacuated tube collectors under these conditions, but this performance is very good, especially considering these panels are now 29 years old.  It is unlikely that I will ever have to replace these panels, for given their current condition, I estimate their working life to be approximately 50 years.  But if I did replace them, I would stay with flat panels

Upper right. Discharge temperature from 300 liter storage tank.


Lower right. Return temperature of antifreeze in panel loop.  This temperature is after the heat exchanger. The water entering the exchanger from the panels is about 58c. 

Repairing a RapMan Controller

Has the extruder stepper driver circuit failed in your RapMan or BFB 3000 controller board?

Here is how I fixed mine in about 20 minutes using only a single piece of wire!

The BFB board Version 3.3 Part #30003 is used in both the RapMan 3.1 and the BFB 3000. These boards have 3 Extruder outputs.  That means your RapMan 3.1 has a built-in spare!  Or TWO spares if you are running a single head.  The trick is how to access those spares?  While in theory it could be done in the firmware, I don't have the ability.  So, I went for a hardware based solution. I began by tracing the circuits until I was able to identify the critical wires.   It turns out that BFB made things exceptionally easy by sending all 3 extruders the same signals in parallel, and only making the "Enable"  signals separate.  That means that only one jumper is needed from the Enable #1 trace to the Enable #3 trace.  The only other thing that is needed is to cut the traces leading TO stepper driver #1, and FROM the CPU to stepper driver #3.  After that, just move the wires on the 25 pin connector from Stepper #1 to Stepper #3. 

The driver chip is an Allegro A3979, and is available from various distributors.  Replacing them is challenging, for the bottom of the chip is soldered directly to the board, which acts as a heat sink.  This means that you can't simply heat the pins and remove the chip.  I removed mine by heating the opposite side of the board with a large soldering iron after cutting the pins free and removing them.  Unfortunately, I damaged the board in the process.  That is when I decided to abandon the repair attempt and go with the far easier jumper fix described above.

Update:  When I did this repair, extruder mapping was not in the firmware version available at that time.   Now it is, and that renders this fix obsolete.  However, you may have to replace a driver chip someday, like I just did when I fried another one. The Allegro chips do not tolerate having their outputs grounded. Having learned from the first disaster, this time I used my milling machine to cut the body of the chip away, leaving just the pins.  These were now easily removed one at a time with a small tip soldering iron.  Mouser's catalog listed the Texas Instruments DRV 8811 as a direct replacement, with a disclaimer, of course.  I looked at the pin arrangement, voltages, and everything looked good, so I bought some.   I soldered one in by first putting a small blob of solder on the circuit board heat sink pad and then heating the board from the back.  The chip nicely settled into place, and then I soldered the pins.  Sure enough, the chip ran the extruder drive nicely.  Interestingly, the motor is much quieter, for the TI chip runs at a lower PWM frequency. The motor also runs slightly cooler, but has the same torque as before.  However, when I tried printing, something was wrong.  Soon I realized that the stepper was running too fast.  Twice as fast as it should.  Then I remembered Mouser's disclaimer and went back over the data sheets for both the Allegro and TI chips.  The Allegro offers full step, 1/2 step, 1/4 step and 1/16 step.  The TI has full step, 1/2 step, 1/4 step and 1/8 step.  The BFB board was set for 1/16, and the TI chip was running at 1/8, or twice as fast.

Rats.  There was no way the fragile pads on the circuit board were going to survive another chip change, and the TI chip is otherwise a very good chip. I decided that instead of removing the chip, I would slow it down by slowing down the signal controlling the chip.  The speed of the stepper is determined by the frequency of the incoming pulses.  So, I decided to cut the frequency in half by making a divide by 2 circuit from a flip-flop. I mounted this chip on a separate board, and then cut the control line to the extruder on the back of the board. 

Wires from left to right:  Ground, Clock input to flip flop, "Q" output from flip flop, and +3.3 volts.
This works perfectly.  My two extruders now track perfectly in speed, with the only noticeable difference is that the motor being driven by the TI chip is quieter.

My divide by 2 trick does not turn the TI chip into a 1/16 microstepper.  Rather, it is more accurately a 1/8 microstepper running at half speed.  This is not a problem on an extruder drive which is running anywhere from 24 to 90 RPM.

Installing a Tailstock Cam Lock on a 7x Mini Lathe

I purchased a Mini Lathe Tailstock Cam Lock from Little Machine Shop.  It is a well made kit.  Actually, I think it is superior to the factory installed locks I've seen on some Mini Lathes.


This is normally an easy to install kit.  However, my tailstock casting was quite uneven where the kit would be resting.  I decided to machine the bottom of the kit to match the angle of my casting.

I had to cut a compound angle and file a radius on the bottom of my kit to get it aligned correctly. Once I had a good fit, I drilled the hole for the shaft.

 

Even though cutting the angle made my kit shorter, I nearly came out of the top of the flat area on the rear of the tailstock.

 Like everything else on this casting, this flat area was not flat, so I milled it flat.   Then I added a flat washer and a wave spring washer to eliminate the sloppy feel of the handle when in the unlocked position.  It works fine without it, especially of you install a spring like the one included in LMS's Tweaks.&.Enhancements kit.  But I like to make everything feel as precise as possible.

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A front view.  I am very pleased with this kit.  It operates smoothly and locks solidly. A vast improvement over the original lock nut.