The 2009

Algore* Edition

GREEN Hybrid


*: Named for the faithful  and longtime Hoyt-Clagwell drill press operator Thurlow Algore who died suddenly one day while practicing his golf drive in the company's tile lined employee shower.


10 September 2009:

Well, I've gone and done it again!  Got a brainstorm that won't quit so there's nothing for it but to design a butt-buggy around the Homebrew Hvid engine.

I'm starting out with the Hvid engine.  Gonna use a fixed-up Sears transaxle, the same as in the Hoyt-Clagwell 54/75 but with a Green twist.

The engine's going to run a small alternator that floats a 12 volt battery that is used to power a motor that is connected to the transaxle. 

As of now, I'm going to use a car window regulator motor and gear for steering so it can also be called "Fly by Wire"!  High-Tech!!!!

First things first, though.  I had a motor off of an old washdown pump.  I'm not sure it's gonna have enough muscle to do the job but I figured the ratios out and in low-low gear, it's a bit over 100:1 so I won't need much power to move slowly.

I need a controller so I designed a 40 Amp Pulse Width Modulation controller.  Since the motor draws about 20 Amps with a locked rotor, the controller will survive.

The PWM controller, in process.

Since I'm so cheap, I designed my own controller.  It consists of a dual opamp, a couple of small bipolar driver transistors and four MOSFETs.  Speed of the motor is controlled by a potentiometer and I think I'll just mount it on a fender instead of using a pedal.

The custom Hoyt-Clagwell Ammeter.

I needed an ammeter and, again, not having one and being too cheap, I delved into the junque box and found an old 100 microamp meter movement that I made a shunt for and re-scaled to 20-0-20.  Of course, it has the official Hoyt-Clagwell name on it.

I'll have to finish the drawing of the frame so I can get the steel and start gluing it together.  I'll most likely make my own seat so I have the proper "Reclining" repose when cruising along.


12 September 2009:

Today, I got the motor mounted on the transaxle.

Motor lined-up roughly to get an idea of the position it needs to be in.

After shimming the tranny so it was level (as it will be when mounted in the chassis), I used the machinist's level to lay out the motor mount.  There are two "mystery" bosses on the side of the tranny you see here, threaded for 5/16-18 that I used.  On the other side, I made an angle iron piece that bolts to the brake mount and extends to the motor mount. 

Motor on finished mounting frame.

Again, I went to the scrap shelf and got an end of a piece of square tube and some angle iron.  I cut the tube lengthwise to make a "C" channel for the upright.  Some 1" X 1" and 2" X 2" angle iron makes up the rest of it.

After cutting, filing, cussing and welding, the motor mount is finished.  It's kinda "hangin' out there" but is steady enough to work fine.  I made the mount a bit larger than I thought it needed to be, but I may have to get a larger motor depending on how this one works out.  It may be a bit wimpy for anything but the lowest gear.

The pulleys are from a surplus outfit and the belt is a spare for my lathe.  Both of the pulleys had to be modified for this use.  The one on the tranny had to be bored in a taper to fit the shaft.  The motor pulley started it's life as an idler so I pushed out the bearing and bushed it to fit the motor shaft.


19 September 2009:

A few days ago, a friend from the south of the State dropped by on his way to Texas and we did a little swapping.  He ended up with the Delco starter-generator which wasn't going to work out and left me some parts for the project, including a front axle, front wheels and a Delco alternator.

I belted the alternator up to the engine and checked it out.  It works fine but is capable of making the Hvid engine fall on it's face if you make it work.  I've tried a couple of schemes to limit the charging current without having to re-invent the voltage regulator and have been semi-successful.  After the tractor is runnng, I will most likely have to come up with a regulator that will allow me more efficient control of the charging current and voltage.  Because the power output of the Hvid is limited (unless I want to spin it faster than I like), I will have to use careful power management.

I've been working on the front axle.

A friend swapped me for this lawnmower front-end.

I had to make a pivot bushing and pin as well as king pin bushings for one side but it is going to work fine.  He gave me six front wheels and he thought I could take the four pneumatic bolt-together wheels and make two good ones.  They ended up being too rusted out to use so I had to resort to the third set of wheels, which are semi-pneumatic.  I had to bore the plastic bushings to fit the 3/4" spindles.

Transaxle with motor, controller and cooling fan mounted.

I had to use an old computer power supply fan to cool the motor.  When I bench tested it, it got too hot to touch.  With a good breeze blowing over it, it stays cool enough to put my hand on when running with no load.

The frame rails will be 2" X 4" X 1/8" steel tubing.  It will be wide at the rear to accomodate the tranxaxle and narrow at the front to fit the engine. 


23 September 2009:

I now have the frame rail material and the auto window riser motor and gear.  Tomorrow (if the creek don't rise!) I'll start cutting the frame pieces.


26 September 2009:

Yesterday and today, I've been working on cutting and mitering the steel for the frame.

Since the frame is narrower in the front, I had to miter the rails 22-1/2 degrees where it slims.  Because the metal won't fit in the mill so I could use the quill tilt, I went to my CAD and laid-out a 11-1/4 degree angle then printer-plotted it and glued that to a piece of 1 X 2 wood.

Using angle board to set the workpiece.

Milling the miter.

After cutting out the angle in the piece of 1 X 2, I laid it on the workpiece which is clamped in the mill vise then used a spirit level to make the top of the angle board horizontal.  Voila!  A 11-1/4 degree miter.

Bolt spacers welded in place.

One of the things I had to do before finishing the rails was to cut out the rail for the rear axle and drill the holes where the tranny mounts.  I made the reinforcing tubes out of a piece of 3/8" iron pipe.  The tubes will keep the tranny mounting bolts from crushing the frame tube.  In addition, on the left side, a hole had to be sawed for the tranny oil filler pipe to go through.

The frame, laid together prior to welding.

Tomorrow, I'll make some smoke and bright light.


28 September 2009:

The extensions for the front axle got made and a hole was sawed into the rear front crossmember for the radiator water line to go back to the engine.

Then I spent about two hours clamping, banging, measuring tacking and swearing to get the frame lined up for welding.  I tacked it with the MIG welder then used the buzz box to finish them off.

The frame welded and being cleaned-up.

Once the welding, grinding and chipping was done, I laid the frame on the rear axle and had an "Aw Shoot!" moment.  I knew I shoulda put the PWM controller in the CAD when I laid out the frame.  The heatsink bangs into the crossmember just behind where the frame gets wide.    DRAT!  What I think I'll do is to shorten half of the heatsink fins an inch or so to give room for it to fit where it is now.  I know you'll never tell.


3 October 2009:

The other day, I visited the local Pick-a-part junkyard and got a window lift assembly.  After whittling on it a bit, here's what I've got for a steering drive.  I also primed and painted the frame previous to assembly so it would be sure to get scratched-up in the process.

Modified Window Lift Assembly.

Upside down frame with steering drive in place.

Steering connected and ready to go.

I had to make a tie rod and drag link.  I temporarily hooked the drive up to the battery and it will, in fact, turn the wheels.  I don't have a clue what the Ackermann angle is on the front axle.  It's for a small riding lawnmower with a much shorter wheelbase, so I'm about sure it'll scrub the front tires in tight turns.  If it's not too bad, I'll leave it alone.  

Here's the frame with the front-end, battery box and tranny mounted.

While I was fiddling around with the battery in the chassis, I decided to see how it would run.  Not well!  Either my battery was dead or the motor is much too weak to do the job.


4 October 2009:

The control panel is about done.  

I have to wire it and make the remotes for the steering and motor control.  I may just put pedals on the tractor and use one for the brake and hook the other one to the motor control potentiometer. 

The relay and steering diodes are behind the panel on the left.  The steering will consist of two buttons.  One of them for "Left" and the other for "Right.  It was a little bit of a mental stretch to make sure that, if both buttons were pushed at the same time, the control wouldn't explode.


7 October 2009:

The engine and radiator are mounted and enough wiring is done for it to move.

The 2009 Hoyt-Clagwell with temporary sporty bucket seat.

It ain't a-gonna be doin' any wheelies but it does move.  I still have the charging system to sort out and, of course, get the seat, fenders, running boards and pedals done but it's at least moving and steering.

The blue box hanging off of the bucket seat is the steering control buttons.  Green for left and red for right.  Maybe I oughta name the directions "gee" and "haw".  That would be fitting.


11 October 2009:

Still working on the charging system.  While fiddling with the original internal voltage regulator in the alternator, trying to make the charging current variable, I let the smoke out of it.  Then I did what I should have done in the first place.  I removed the internal regulator, brought the field lead out of the alternator and designed a custom voltage/current regulator.

The breadboard "rat's nest".

The completed "brassboard" version.

After a day of fiddling with the circuit, I got it to work in breadboard form but, after sleeping on it, decided to start over because the dissipation of the field driver transistor was just too high for me to be comfortable with.  

The second iteration works much better.  I should say "worked" because after carefully documenting what I had, I made a "brassboard" of the circuit.  Now, it doesn't work!  Not to worry - that's about normal when designing a new circuit.  Either I got something wrong or the balderdash factor has kicked-in.  I'll get it done tomorrow so I can get on with the project.


18 October 2009:

Yesterday, the 2009 Algore Edition Hybrid Green Hoyt-Clagwell made it to it's first show!  The occasion was Goat Day at the Florida Panhandle Pioneer Settlement in Blountstown, Florida.  All I can say is that we made it to the show but the Hoyt-Clagwell wasn't ready for prime time.

Not quite ready to show!  Note the "drip-catcher" under the engine.

First, the electric drive motor doesn't have enough power to pull the tractor up onto the trailer.  Second (and most important), it was plagued with exhaust valve sticking all day long.  It took about a half a can of WD-40 to keep it going.

Then, since on the morning of the show, it was cooler than I'd ever tried to start it, I bent the camshaft a little while hauling on the crank.  That's one of the things I've got to re-do.  I think I'll go with a larger shaft so that won't happen again.

On the exhaust valve sticking, I'm going to ream out the guide 'til it's got about 0.005" of clearance (sloppy!) to see if I can alleviate the problem.  There should be a point where the carbon can't build up enough to stick the valve.  If the guide's really loose, maybe it'll carbon-up to a good fit.

I've also been thinking of seeing how it will run using Diesel fuel for ignition and letting it inhale propane for running.  The big engines can do it, so I don't see why it wouldn't work in a small Hvid.  We'll see.

On the matter of drive motor power, I'll have to re-think that also.  I could go with a "store bought" 24 or 36 volt motor and controller but then I'd have to work on a way to charge the batteries.  Maybe the alternator stator "armature" can be rewired in series (instead of three phase) and use a half-wave rectifier to get either 27.6 volts (for a 24 volt battery) or 41.4 volts (for a 36 volt battery). ........  Again, we'll see.  I could blow-up a perfectly good alternator but, that's the price of science!


29 October 2009:

I've closed-out new entries for The Homebrew Hvid engine and will continue development of the engine here, on it's tractor.

In the time since my last entry here, I've reamed out the exhaust valve guide and it now is running somewhat over 0.005" clearance.  I've also replaced the 0.625" camshaft with a 1" shaft so it won't get bent again.  

I suppose this is the way engines and other machines were designed and production-readied years ago.  The designer (not necessarily an engineer) would make drawings of the engine in order to have a good chance that the parts to fit when it was built.  Then, he made the casting patterns for the major parts and once they were made, he machined and assembled the parts.  Then, time was spent making the engine work in some fashion and more time was spent modifying parts and running the engine while making further adjustment.  After a lot of time was spent refining the design, it was either abandoned as unworkable or finally readied for manufacture.  We don't do things like that today, in the age of CAD/CAM.  I don't believe it's nearly as much fun!

Anyhow, since the valve guide and cam fixes, the engine has run for about three hours with no problems so maybe that tweak was successful.

The jury's still out on the generator and drive.  Since last time, I've rewired (not rewound!) the alternator windings to a single phase full wave configuration, trying to make 28 volts, necessary for charging 24 volts worth of batteries which would run a 24 volt traction motor.  I was able to get 28 volts out of it and several amps but the field current has to be high enough to use up most of the engine's output before anything useful is done.  This is a problem with trying to make something do something it wasn't designed to do.  Sometimes, you can get away with it and other times, you can't.  This was one of those "can't" times, so I'm back to the original three phase full-wave configuration with home-made regulator.

I'm in a situation here where, if I run the engine at about 1,000 RPM, it will make sufficient power to generate properly but if I do run it at that speed, I've got the fear that something will break or that the rod bearing will throw grease too badly to survive for long.  Right now, the engine's running happy at 800 RPM (a bit below what I think is it's peak power RPM), which incidentally is the speed I originally thought it would be happy at.

I now have three choices to make.  On the traction motor, I could get a 12 volt motor of about 500-750 watts and use my present controller.  That would give adequate power for driving around but, since the generation capacity is not very good, I would have to stop occasionally to let the battery charge.  No biggie at a show but a pain to keep track of to avoid harming the battery from over-discharging.

Now, there's another generation plan but it's just a plan at this time.  My friend Frank, in Kentucky, has expressed interest in designing a magneto a bit like the one on the Model T Ford but on steroids using rare-earth magnets.  The magneto would consist of a bunch of permanent magnets on a flywheel face which run opposite to a bunch of coils mounted on the engine frame.  The advantage is that it is a lot more efficient than the automotive alternator.  The disadvantage is that it would be difficult to make the parts and would most likely require redesign of one of the main bearings for absorption of the added end thrust.  If this idea were to be used, I could go back to the 24 volt system and simply use a dropping resistor for the steering.

The other plan would be to use the two 90 volt permanent magnet motors, one as a generator and the other as a traction motor.  I'd have a new Pulse Width Modulated controller to design and build (no biggie) plus, there's the matter of the 12 volt steering motor.  With the 90 volt  arrangement, there would be no reasonable way to power it although I guess I could retain the 12 volt battery and just recharge it at times but it seems to me to be a sort of cop-out on the design.

We'll see.


31 October 2009:

I ran the engine another three hours today and, aside from running out of fuel, it did well.  The jury's still out on the sticky exhaust valve.  It may take more than about 5-6 hours to clog it up again.

Since the alternator's rewired to it's original three phase configuration (with the home made regulator), while it was running, I took the electrolysis can and some meters out and did a bit of testing.  The setup had the electrolysis and the voltmeter across the battery, and an ammeter in series with the alternator output.

Current was varied by changing the depth in the electrolysys solution of the workpiece.  With this arrangement, the maximum current that could be produced by the alternator was about 15 amps, far more than the engine could pull using #2 fuel oil.  Incidentally, I worked out the maximum current by trying something else with the engine.  While it was running, I held an unlit propane torch up to the intake and it made more power than on oil alone.  I then maxed-out the load and the engine would just pull it.  That ended up being around 190 watts, not too shabby and better than twice what the engine could do with oil alone.

The reason I wanted to try the propane is that a lot of the really big Diesels were run on natural gas and they did fine on it.  Interestingly, the oil injection must still be used because the gaseous fuel will not ignite at fuel oil compression ratios so the oil ignition is used for ignition of the gas.  The same thing is true with Hvids.  If  you turn off the oil while it is running on propane, it immediately quits firing.

Anyhoo, varying the load on the engine, I came up with the following measurements.


Alternator Amps    Batt. Volts   Watts    RPM    Comments

          0                        13.9        0          790      No load, very little smoke

          1                        13.9        13.9                  Minimum smoke 

          2                        13.9        27.8                    

          3                        13.9        41.7     737    

          4                        13.8        55.2 

          5                        13.7        68.5

          6                        13.5        81.0     689       Max engine can pull continuously. Heavy smoke

          7                        13.6        95.2                  Engine slowy bogs, flywheel giving up energy

          8                        13.6      108.8                  Engine bogs faster

          9                        13.5      121.5                  Can only sustain load for five seconds

         14                        13.6      190.4                  Max cont. with propane fuel added


While the engine was working hard, I stuck a thermocouple into the top tank of the radiator.  It was running about 160 degrees F.  At the exhaust side of the head it was around 200 degrees F.

Next week I'm going to scrounge around the scooter stores and see if I can find a 24 volt motor that's rated at about 500-600 watts.  I'll mount it up to the tranny and use the controller I built and run it at 12 volts (125-150 watts) to see how it does.  If the Hoyt-Clagwell does all right (no stump pulling, please), I'll leave it as-is.  If it can't do the job, I'll have to consider a 24 volt system and figure out a way to successfully charge the batteries.


4 November 2009:

I decided to go ahead and buy a new 500 Watt 24 V scooter motor and controller.  While I was at it, I've ordered some #25 chain and a sprocket from a surplus outfit.  

In anticipation of having a butt-buggy that will move fast enough to require brakes (wishful thinking on my part!), I hooked-up the brakes on the transaxle.

It's kinda hard to see how the linkage works but it is a little like the original Sears lawn tractor setup.  I had to make the brake lever mount, arms, etc. and the spring arrangement.

You will also see the semi-completed motor mount.  I had to make this angle bracket because the motor I'm getting is face mounted as opposed to the original motor which was base mounted.  Once I get the motor, I will finish it.  I will have to make a hub for the driven sprocket to fit the tapered input shaft of the transaxle.  The motor comes with an 11-tooth sprocket and I bought a surplus 33 tooth sprocket to adapt to the tranny.  Instead of 1-1/2:1 between the motor and the tranny (like before), I will now have a 3:1 ratio to give me a little more torque to the wheels.

All I gotta do now is wait for UPS.


7 November 2009:

UPS got here with the motor on Thursday and I got it ready to go.  Friday, the sprocket and chain arrived.  

It's all done!  The test drive was around the neighborhood, through a vacant lot and up some pretty steep inclines.  It isn't fast by any means, but in low/low gear, it will really pull, albeit slowly.  It will pull itself reasonably well in high/high on smooth pavement and goes at about a middling walk.  After testing, I now declare the 2009 Algore Edition Green Hybrid Hoyt-Clagwell semi-ready for prime time!  

AND, here's the Youtube flick:


10 November 2009:

After my test run the other day, I decided that I needed a "clagpipe" to get the smoke out of my face.  I made up a pipe and now the exhaust comes out just behind the radiator and up about six feet.  Much nicer for driving around with only the occasional whif of clag.

By the way, I've been informed by my Brit and Aussie friends that the term "Clag" was slang that originally referred to the white starch paper paste used by schoolchildren.  Today, general useage is to indicate something dirtied-up and, most commonly, clag is the heavy smoke from Diesel engines.  Now, I wonder if the name of the tractor didn't, in fact, refer to a tractor that smoked very well.

Anyhoo - I have a few small chores to perform, one of them being a slight re-hash of the voltage regulator.  The voltage adjustment trimmer pot is defective and it is tricky to get the voltage to set at 14.1 and make it stay there.  No biggie.

The pulse-width-modulation I made also has a minor problem with false triggering of the MOSFETs that causes jerky motor action at low speeds and high loads.  That one will be addressed ...... ...... sometime.


13 November 2009:

Yesterday, I got the tall "clagpipe" on and went for a drive.

With the tall clagpipe.

After I got back from my ride around the neighborhood, I noticed some little black thingies on the tractor and on me.  I tried to wipe 'em off and found out that they are soot from the engine. They smear like the dickens and are really hard to get off.  I'll call them "clagboogers".  When I was getting ready for my shower, I looked in the mirror and ..... egad!  I had black smears all over my face!  Clagboogers are definitely not on so today I revisited the clagpipe.

The new "anti-clagbooger" clagpipe.

Now, that's a LOT better!

While rummaging around my air compressor, I noticed that it had two cute little (4") pneumatic wheels on it.  The Hoyt-Clagwell has 4" semi-pneumatic wheels on the front and so a swap is in order.  I will have to rework the hubs and bearings but soon I will be sporting proper front tires.  The air compressor won't know the difference anyway.


December-January 2010:

I finally got tired of all the smoke and stink of the Hvid engine so I made a new cylinder head for it along with a mixer, etc. and it is now low-compression, naphtha burning, using spark ignition.  It starts a lot easier, is quieter and, best of all, it doesn't stink!

From this point onward, the photos will show the tractor with the naphtha head on it.


30 January 2010:

I've been doing some "refinement" to the mechanicals and the electronics.  First, because the engine just made too much soot and really trashed my clothes, I made a new head and converted it to spark ignition and it now runs on naphtha.  You can see the process by going to The Homebrew Hvid pages.

Then, whilst testing the drive on some slopes, the jerkyness in the motor controller finally bit me in the you-know-where, making the smoke leak out of the MOSFET motor driver transistors.  I found that the jerkyness was caused by noise spikes getting into the PWM circuit from the "accelerator" pot.  Adding a 1 microfarad capacitor to the arm of the pot solved that problem and, with four new MOSFETs, I am back in business ..... smoothly.

THEN, I decided that I needed to come up with a little more elegant steering system than the buttons.  It is hard to steer a straight course with them.  What I came up with is a kind-of rough-and-ready servo system.

Window regulator with servo follow pot mounted.

Servo circuit.

The servo uses a dual op amp.  The steering pot (shown below) controls one of the opamps and the follow pot controls the other.  I use a hex CMOS Schmitt Trigger to set the direction and cancel out offsets in the opamp.  The output is four MOSFET transistors hooked up in a bridge configuration to drive the window regulator.              





I rooted around in my leftovers and found a bunch of slider pots from a stereo mixing board I'd built, used and scrapped in years back.  I made a housing out of PC board material and, so as to be universal, labelled the directions in four languages as you can see.

Today, I put the steering on the tractor and found that the MOSFETs aren't up to the inrush current of the motor.  Needless to say the magic smoke leaked out.  The fallback is to simply use a couple of relays for motor drive.  The paralleled CMOS Schmitt-Trigger circuits should prove to be able to drive the relays.  I'll remove the output transistors and replace 'em with the relays.

I was getting a little wary of using the rotary pot on the steering box to control speed.  If it got bumped with the tranny in gear and the brake off (later in this narrative), the tractor would move off on it's own.  Not good.

"Foot feed" Assembly.

Speed potientiometer, gears and slip clutch.

What I did to solve that problem was to make a "foot feed".  I had some junk gears that I could get 1:4 out of (1 on the pedal to 4 on the pot).  This made the angle the pedal moved through about 68 degrees to get the full 270 degree range of the pot.  The pedal stops are set just a little more than that and the slip clutch made up of a spring pressing the big gear against the shaft hub finished it off.


"Foot Feed" mounted.

The control box is getting full!

Since I will be running this at shows (that allow it), I wanted to have a foolproof system for shutting off the motor drive when the brake is applied.  A switch is mounted so it opens the circuit from the speed pot (foot feed) to the motor controller when the brake is on.  

I also made a locking lever so I can use the regular brake as a parking brake.  Pull the service brake and lift-up on the locking lever and the brake stays on.

I've also been thinking of making the engine go to idle when the battery is fully charged, returning to speed when the battery starts discharging.  I'll do that sometime later if the spirit moves me.

If anyone wants to see the circuit diagrams I've developed, let me know.  I will formalize them and post them here.


15 February  2010:

Over the last few days, I've just been piddling around with the project.  One of the things I wanted to do was to arrange it so that when I had the alternator and drive turned off, the engine would go to idle.  Looking in my solenoid box I found that all I had was a few coils so I proceeded to make a frame and armature for it that turned it into a magnet.  I then made a button that would be pulled into the magnet when it was energized.  There is a spring hidden inside.

Home-made idle magnet.

The magnet, when released (alternator and drive off), pushes the governor lever toward idle.  When I turn the alternator and drive back on, the magnet grabs the button and allows the governor to control the speed.  It ain't poifect but it works.

Ringy ding-dinger.

Then, since I needed some sort of attention getter (for warning pedestrians that I was near), I rooted around and found an old elevator alarm bell from way back.  It works nice.

Today, I made a fitting for a thermocouple so I can measure the coolant temperature.  I don't know if I'll leave it on but, until I figure out what the best operating temperature is, it will be handy.  The other day, I stuck a thermocouple in the top tank of the radiator and it was only running about 140 degrees, too cool in my mind.  I'll probably put a gate valve in the line from the block to the radiator so I can slow the flow and raise the temp.


16 February  2010:

After I finished the thermocouple fitting and screwed it into the water jacket outlet nipple, I said to myself, "Nawwww.  That's too modern looking!"

The -too- modern looking thermocouple fitting.

After about a minute of thought, I figured out what I was going to do.  Since I rarely run my Jack of All Trades engine and really don't need it, I removed the fancy brass thermometer from it and laid-out what I was going to do.

And a fine piece of steel scrap it is!

The piece from the scrap pile was just about what I needed.  I flycut it square (left the nice radiused corners) then flycut about 1/4 inch off of the thickness.  Drilling the passages was done next.  The thermometer is 1/2" NPT and this was bored and threaded without incident.  Then I started on the pipe fitting threads which are 1/4" NPT.  That's when the AWSHOOT! happened.

Broken tap!

SNAP!  Gee, Ma.  I wasn't pullin' on the handle THAT hard.  I suppose that's what I get for buying cheap taps.  This one was almost new but, from Spain.  They must make 'em brittle over there!  At first, I wasn't too worried because there was a pretty good piece of it sticking out of the hole.  Not so lucky!  I spent over an hour getting it out, finally having to resort to breaking it up with hammer and punch then drilling a hole from the opposite side to drive the remaining chunk out.  THEN, I boogered-up one of my other taps (this one was about worn out), chasing all the bits of tap out of the threads and cleaning them up.

The other two 1/4" NPT holes tapped fine with a cheap tap in a set I bought years ago.

Ready to assemble.

In the above photo, you can see the near finished thermometer and valve body.  You can also see the 1/4" pan head screw that is in the hole I had to drill to get the piece of broken tap out.

I drilled a 1/4" NPT tap drill diameter passage straight through from the upper left to the upper right.  Then I counterbored the right-hand end of the hole to 1/2" NPT tap size.

The lower right hole was drilled 1/4" NPT tap diameter almost all the way through (before the "rescue" hole was drilled from the other end). 

The hole you see at the bottom (where the valve stem goes in) was drilled 1/4" NPT tap diameter until it intersected the previous hole.  The drill bit was replaced with a 3/8" bit and the hole was drilled the rest of the way to the first passage.

The valve was made using some scraps and a 1/4" NPT to 1/4" tubing fitting.  I tapped the fitting 1/4-20 and made the stem with a 1/4-20 thread partway along it's length, allowing a slick surface for the string packing The head of the valve is 0.430" in diameter, enough bigger than the 0.375" seat to seal relatively well.  I wasn't going for the best seal because I figure there must be some leakage or the hot water will never get to the thermometer if the valve closed completely.

Tomorrow, I'll finish up the fitting, install it and see how it works.


17 February  2010:

Well here it is.

Thermometer in place.

The first thing I noticed was that the water outlet temperature didn't seem to be rising much even with the circulation almost cut off.  The highest reading I could get was about 150.   Using a thermocouple against the nipple between the jacket and the thermometer block, I measured about 25 degrees hotter.  When I wrapped a rag around the thermometer block, the thermometer rose to within about 10 degrees of that of the thermocouple.  The thermometer block is sinking some heat from the coolant.  I've now got the correction factor in mind and will run it in the 140 to 150 degree range.


30 January 2011:

The 2010 Algore Edition Green Hybrid Hoyt-Clagwell has now been repowered with the Non-McVickerish engine and The Homebrew Hvid engine has been converted back to HVID and set-up on a roller skid for display.

The Non-McVickerish Powered 2009 Algore Edition Green Hybrid Hoyt-Clagwell.

To carry The Homebrew Hvid around at shows, I've made a carrier to fit the tractor.

Preparing to back into engine.

Engine and lifting arms in place.

Engine in carrying position.

Locking device to hold the engine up.

After the engine is in place, if it is to be moved a distance, I'll use a nylon strap come-along to secure it to the carrier.  With the engine in the carrying position, the tractor is a bit light in the front.  I find that if I lean forward when driving, it steers better.


16 May 2012:

After running several different engines on the 2009 Algore Edition Green Hybrid Hoyt-Clagwell, I've decided "hybrid" is simply not practical, green or efficient.  If you think about it, you lose more power in the generation of electricity and lose more in the motor losses.  I think it will run better by simply trashing all the "green" stuff and running the chassis with a belt drive from the engine.

Hence, you can now go to the page where it is de-greened:

The 30-60 Hoyt Clagwell

Boy! This is fun!

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