Dividing Head Refurb: Part 1

A little over 2 years ago I purchased this dividing head from an OWWM member. He said it was missing a few pieces and jammed up but the price was good. Finally, I’ve gotten around to working on it. The dividing head has no brand on it but there is a patent stamped into the head. According to the patent records online (from 1890!), this dividing head was made by Cincinnati. While going through the dividing head, I found 47X stamped into multiple pieces. The patents indicate this dividing head was used on a horizontal milling machine. It has a “drive shaft” allowing it to be driven by the milling machine.

If you’re not familiar with a dividing head, it’s a device for dividing a circle into numerous pieces.  It does this precisely by gear reduction and an index plate.  This one can do between 2 and 2640 divisions of a circle but probably not every integer in that range.  More on this in a future post.

This is what I started with. There’s a three jaw chuck, large locking “nut”, curved cover in the box, and bag of small parts.

First, I took the index plate off which just slips off the housing.

With the plate out the screws can be removed that hold the “drive shaft” housing. The wood dowel helped me to move the spindle block without damaging anything. The dividing head has two bolts with a T shaped head to lock the spindle block in position. They can be removed by orienting the hole in the spindle block to remove them. To remove the spindle first required removing the worm gear. The first step in this is to remove the brass “nut” on the worm gear shaft. It wasn’t tight and I found the best tool I had to remove it was a pair of bent needle nose pliers. Once the “nut” was removed, a spacer, and the part I’m going to call a thrust bushing can be removed. The bushing just sits on the shaft but it took be a little bit to figure out a way to grip it to pull it out using some large retaining ring pliers (not the adjustable wrench in the pic).

At this point I had access to the worm gear and the shaft it is on. This took me the longest time to get out. Eventually, I realized I could thread a regular hex nut on the end of the shaft that I could pull on with my fingers. While doing this, I turned the spindle (using the gear and shaft that the arm with plunger would normally turn) so that the force on the worm gear would help push it out. Finally, it came out. There are some spacers that go on the smaller end of the spindle. I thought they were threaded in initially but it turned out they just slip over the spindle. I oiled them and was able to get them removed with a magnet. There’s also a big round piece that screws in to hold the spindle in place. It was already removed when I got the dividing head but, for anyone else, it has to be removed to get to the spacers. This circular piece holds in a couple parts that lock the spindle in place. The piece was held in place by a pin on the back side of it. To remove it, I slowly worked it loose going around the outside with some scrapers. With the worm gear removed, the spindle is able to be removed in the direction of the smaller end. In the picture, the spindle brake piece is shown on top of the spindle. 

To get the shaft out this casting I needed to first remove the bevel gear which required moving a taper pin.  This pin was stuck in and I tried driving it out with a hammer.  I was afraid I might damage the casting if I kept it up and instead chose to drill it out.

At this point I had the diving head completely disassembled.I’ll cover reassembly and making some missing parts in future posts.


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At Home Rust Bluing

The other day I decided to improve the hold downs on my milling vise. My current hold downs use a stack different sized washers that were with the mill when I got it. I decided to turn some pieces out of steel to replace the stack of washers. My “new washers” are 1/4″ thick and around 2″ in diameter with a 3/8″ hole.

I turned two of them and then decided to “cold blue” them with Birchwood-Casey Perma Blue. A simple dunk of the part in the solution resulted in a nice uniform deep blue color. I liked the results but the I’ve read this coating is very thin. The solution is also relatively expensive for the amount you get.

Due to this, I started looking into other types of coatings to use. I ended up running across a YouTube video discussing a type of bluing that can easily be done at home. I followed the instructions in the video but didn’t get as good of results as I hoped. Instead of the desired uniform blue coating I ended up with a mostly blue coating speckled with spots. He didn’t in the video though. This lead me to do more research on the method. It turns out the video is describing a variant of a technique typically used by gunsmiths to blue firearms. I was then able to read up on the technique and try it out.

The technique consists of lightly rusting the piece of steel and then boiling it in water. Boiling the piece in water converts the typical red rust into a black oxide (also called magnetite). Unlike red rust, which will slowly eat up the steel, this black oxide coating is stable and when oiled provides a durable coating.

I took my washers with the speckled finish and stripped it off using some vinegar. Next, I used some 220 grit sand paper to smooth out the surfaces. Below is one of the washers I started out with.

Before starting, I thoroughly cleaned the piece several times with Acetone. I also wore latex gloves the entire time to keep from contaminating the part. Originally, I cleaned the washer with mineral spirits but people online indicated that mineral spirits can leave a residue. It’s important to completely clean the part to remove any oil and keep it oil free throughout the process. As you might guess, oil will stop the formation of rust. To speed up the rusting process, the video uses mixture of hydrogen peroxide and table salt which is brushed onto the washer. The reaction fizzes white and then turns rust colored.

As suggested by the video, I used a heat gun to dry the washer off which quickly resulted in a light rust coating. I repeated brushing on the solution and drying it to build up a uniform coating of rust. If the heat is carefully applied, the solution will dry after a few seconds which keeps the solution from building up along the edges of the washer. The build up can in the rust not looking uniform.

After uniformly rusting the piece, it is then placed into boiling distilled water. Some use tap water but others suggested distilled. The piece is kept in the boiling water for around 5 minutes. From what I read, it’s the heating of the rust in a low oxygen environment which results in the conversion to black oxide.

After the piece is removed, it is coated with a relatively thick layer of magnetite which is loosely attached. On the threads I found, the gunsmiths referred to this a “velvet” which is a pretty good description. As you can see in the picture below, the surface is a matte black and you can still see the brush strokes (and a damp spot). Once removed from the boiling water the piece will dry quickly but should be moved around to keep the water from pooling in one spot which will effect the finish.

The gunsmiths then say to remove the “velvet” by either gently wire wheeling or using de-oiled steel wool (I sprayed mine with brake cleaner) to clean the surface in a process called “carding”. The video I linked to doesn’t mention this step. The first time I went through the process I didn’t “card” the surface which I think is what caused the initial poor results I ended up with. After “carding” the surface it has a shinier uneven look to it. The picture below shows the carded surface though I did still need to clean it a little more.

At this point, the process is repeated . The piece(s) are then re-rusted.

Then it’s back into the boiling water.

The picture below shows the washer partially carded on the bottom with the top still the in velvet state though I’m not sure it comes through well.

I repeated the process five times to build up and even out the coating before moving on to the final step of boiling the piece for an additional 20 minutes after carding. This last step is important and seems to be done to make sure all of the red rust is converted. After that, the washer is allowed to dry before being submerged in oil. I left the washer in the oil for a while to make sure it received a good coating. The addition of the oil results in the color of the surface changing to be a dark blue which is where the name bluing comes from.

Below shows a picture of the washer I cold blued on the right and the one blued using the method I described here on the left. The cold blued one looks a little rougher because I didn’t sand it prior to coating it.

I ended up using the two washers above on my vise to see how the coatings wear. Overall, I’d say I have one of the best looking hold down washers around.

Obviously, this fancy of a finish is overkill on a part like this. But, I wanted to perfect the process and I’m very happy with the quality I ended up with. I’d even say it would look good on a firearm. The process described above takes about an hour so it’s probably best to wait and do multiple pieces at once. The process is also non toxic as it doesn’t use any acids which are sometime used in bluing. About the only concern is the boiling water and the hot part that you remove from it.

I also found out that if you heat the hydrogen peroxide and salt solution will become more active. If you dip your part into the hot solution it will aggressively pit it which is not desirable. The hot solution will also have deleterious effects on stainless steel cookware. If a stainless pot is used for the boiling water the part it will show some stains after use but they can be removed by scrubbing. Either way I suggest a plastic container for the hydrogen peroxide solution and using cheap pots to boil the parts.

All in all, this would make a pretty good at home science project with the adult doing the boiling part. You could buy some standard big Zinc coated steel washers from the store and remove the Zinc coating by soaking in vinegar. The washer could then be cleaned with acetone, lighter fluid, or soap and water. You can rust it using the hydrogen peroxide and salt solution and let it dry without the aid of heat. Alternatively, you could warm it in the oven to dry it more quickly. Boil the washer as described and then let it cool down before carding. A green Brillo pad should work well. You probably won’t get a perfect finish but you can see the process.

In my reading I found that gunsmiths of old would use rainwater to boil the firearms in which was probably cleaner than the other options. These days at-home and professional gunsmiths use special mixtures which are commercially sold to coat the surface that promote rust. The part is then placed in a humidity box which results in uniform rust. The rest of the process they use is pretty similar to what I described above.

Most modern firearms though are hot blued using a process that has acids at around 300 deg which doesn’t sound like something I’d want to do at home. Of course, if you’ve followed this blog for a while, you know I would try it if I felt the need because it can’t be that dangerous. Right?

For more reading see the Rust Bluing section of a Wikipedia entry.

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Wood Canoe Build: Part 3

In Part 2 the canoe was nearing completion.  In this post I’ll discuss finishing it.  The next step was to put a small keel on.  The keel was constructed by trimming a piece of wood to the profile of the bottom of the boat.  The instructions listed a series of points which I splined with an aluminum ruler.

The keel was attached using stainless steel screws from the inside of the canoe and epoxy.  I also utilized this fancy clamping system while the epoxy was drying.

The ends of the keel were sawed to rough shape after marking a line with a compass.The ends were sanded to final shape and I caulked the seam between the keel and hull.

The next step was to install a central brace.  The instructions again detailed how to trim the ends to aide in fitment of the brace.  

Once the brace was installed, using stainless screws through the side of the hull, the rigidity of the canoe was remarkably increased.  Before the brace, the canoe could be twisted along the length without much effort.

The last step in the assembly of the canoe was to install supports for seats.  I marked out the side supports and cut them out.

The side of the ship is curved and required sanding of the support to properly fit it.  Once it fit well, it too was attached with stainless screws and epoxy.

The cross braces were the next part to be installed.  They were sanded to fit an screwed into place.  Supports for seats were installed in the bow and stern of the canoe but in different positions.  At this point I still needed to work out actual seats but that will be covered below.  

Now it’s time for the most exciting part…painting and painting and more painting.  I decided on a navy blue for the hull, a tan color for the inside, and white for the other parts.  Below you can see the progress on painting the bottom.

This shot shows the canoe as I was painting the inside.

Once I was done with painting, I decided on a simple setup for the seats.  They were composed of 1/4″ plywood with some cut down foam.  

Here’s a few shots of the canoe while it was sitting out to have the paint harden in the sun. I haven’t tried it out yet due to all the Covid-19 issues but I will at some point.  When I do, I’ll update the post.



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Wood Canoe Build: Part 2

The work on the canoe continues from Part 1.  Once the sides and bottom had finished drying, it was time to make the pieces start to look like a boat.  The instructions detail how to assemble the hull using a simpler version of a method called “stitch and glue.”  The traditional “stitch and glue” uses wire to attach the pieces of the hull together similar to how fabric is sewn together.  This version uses duct tape instead of wire which turned out to be good and bad.

The first step was to tape the ends together and place temporary spreaders near the top of the sides.  This resulted in the ends pulling apart due to the crummy duct tape I started with.  To overcome this, I drilled small holes near the edges of the ends and used wire to hold the ends together.

Next, I flipped the boat over and started working to attach the bottom to the sides.

I had some doubts about the duct tape successfully holding everything together after the previous experience.  This time I used small tacks to assist the duct tape.  I drilled angled holes first to keep from splitting the plywood.  Then I tapped in the nails and set them below the surface.I also upgraded the duct tape to a heavy duty version which was thicker and had much better adhesive. To apply the tape I started in the middle on both sides and alternately worked my way to the ends as instructed.  After a lot of taping I finally had something resembling a canoe. To permanently hold the boat together I used epoxy and fiberglass tape.  Alternately, the instruction manual says an epoxy fillet can be used on the inside seams.  In retrospect I think it would have been simpler to use the fillet but I managed with the tape.The ends of the boat don’t come nicely since its two pieces of 1/4″ plywood.  The instructions recommend rounding it over with thickened epoxy but I didn’t like that idea.  Instead I epoxied a piece of wood in place and shaped it appropriately.

At this point I was able to start working on the outside of the seams.  Again, I used fiberglass tape and epoxy.  I rounded the edges to help the fiberglass tape stay flush to the surface around the edges.  Eventually, I found wetting out the tape and boat with epoxy helped keep the tape in place. The next step was to start working on wood strips that strengthen the top edges of the boat.  These strips, known as the gunwales and inwales, had to be built up from shorter lengths of wood to reach the required length of 16 ft.  The instructions recommended a simple scarf joint which is a much stronger joint than if the pieces had been butted together.  The scarf joint tapers the wood on both sides of the joint.  To form each joint, I sawed off the waste, stacked both pieces together with the top one offset, and planed both pieces together to leave a smooth surface with a consistent angle.The two pieces were then flipped over, overlapped, and glued together.   The pieces were clamped together and allowed to sit until the glue was dry.  Attaching the gunwales (the piece on the outside) was done first.  It required a bit of glue and a whole lot of clamps.  The instructions mentioned making the gunwales flush in the middle and then raising the strips slightly toward the ends.  The excess material is planned off later.  This is said to give the canoe a “lighter” appearance.  The instructions didn’t detail how to bring the two gunwales together.  Looking for pictures online showed that some builders choose to cut the two pieces off with end of the boat.  I wanted to bring the two pieces together more gracefully.  To do this, I first glued one gunwale in place and trimmed the edge to be parallel with the central axis of the boat.  The other gunwale was then clamped into place and trimmed to fit with the first gunwale.  Once happy with the joint, the second gunwale was glued in place.

The inwales were then clamped and glued into place.  The instructions call for triangular pieces to be glued on the ends of the canoe which go over the ends of the inwales, hull, and gunwales.  I didn’t like the way that would look and instead decided to inset the triangular pieces to be fush with the hull.  This required removing some of the thickness from the inwales at the ends of the canoe.

At this point the project looks a lot more like a canoe but there’s still more work to be done.  That will have to wait until Part 3 though.


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Wood Canoe Build: Part 1

Over winter I’ve been building a wooden canoe.  Specifically, I’m building a Quick Canoe designed by Michael Storer.  Tragically, it’s in metric so who knows if it’ll come out to be the right size.  It’s a two seat version that is a little under 16 ft long.  The plans call for 1/4″ plywood and I’m using exterior grade as opposed to marine grade plywood due to price.

The hull is made up of six plywood panels.  Specifically, there are front and back (sorry…bow and stern) panels for both sides and the bottom.  The plans detail the positions of points which are lofted to give the final curve.  I started by cutting out the two pieces for the bottom.  To do this I marked out the center line and measured out from it for each point along the edge.  I lofted the curve by holding a thin piece of wood against small nails I’d hammered in at each point and marked the curve with a pencil.

After lofting the first piece, I cut it out with a jig saw and then sanded the edges to the lines I’d marked out.  With this piece at the final shape I could use it as a large template.  I traced its edge onto the second piece of plywood and once again cut it out with the jigsaw.  Next, I clamped the two pieces together and used a top-bearing flush trim router bit to bring the second panel to the required shape.

Here’s a close up picture of the router bit. Now I have two very floppy and warped bottom pieces.I used the same process for the four side pieces.   This time using the first side piece allowed me to save marking out the other three panels.The side panels are marked out from a datum line which is the right edge of the plywood piece shown below.

Here’s all four side pieces.The instructions call for backer pieces of plywood to be used to join the front and back plywood panels together.  These were easily cut out on the tablesaw.  The backer pieces were coated with strengthened epoxy (two part epoxy with West Systems 404 High Density Adhesive Filler) and held in place on larger panels.  Below shows the bottom panels getting epoxied together.Unfortunately, I had a lot of squeeze out I was unable to remove it before it dried.  At least I know it’s not a dry joint.  I started to remove some of the squeeze out after it had dried but decided it wasn’t worth the effort.The side panels were easier to glue up and I made a better effort to remove the squeeze out.At this point I have three very cumbersome pieces of floppy plywood that will hopefully become a boat.

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Predator 2000 Inverter

From my last post, you might have guessed that I had decided to look for an inverter generator.  After doing a bit of online research and reading reviews I ended purchasing the Predator 2000 Inverter generator from Harbor Freight.  This generator has a 1 gallon fuel tank and puts out 1600 running / 2000 starting watts.   According to the specs it will run for 12 hours producing 400 watts.  I haven’t tested it yet but have read where some have and got similar results.  Based on running it some it does sip fuel.  Weighing in at only 50 lbs the generator is also highly portable.

The front panel has two 120V receptacles and an odd shaped 12V receptacle. There is also a switch which puts the generator in “Eco” mode which throttles the motor down to the required speed.  Included with the generator is a set of 12V leads that end in two squeeze clamps and some cheap tools.   The generator is also able to be paired to another identical generator to generate twice the rated power output.

One nice thing about the generator is that they took all of the stuff that is actually important out of the owners manual, turned it into a sticker, and put it on top.  There are steps for how to start it, the max load, and fuel type.

Both plastic side panels of the generator are able to be taken off by removing three screws from each side.  From there the insides can be seen.  As this engine has no oil filter I purchased a magnetic oil dip stick to collect bits of metal that are produced while the engine breaks in.  I also added an hour meter to help keep track of runtime for maintenance.  The meter runs off of 12V which I got by slipping wires on to the threaded studs on the back of the 12V receptacle.   It sits inside normally and I’m able to view it when I remove the side panel.  Ideally, it’d be nice to have it visible from the outside but I didn’t want to cut a hole in the generator case.One of the touted benefits of an inverter generator is that quality of the power produced.  Using a step down transformer I measured the voltage with my oscilloscope.   The picture below shows the results on the scope.  The wave appears well formed with no frequency distortion.  The frequency is almost perfectly 60 Hz.In case of a hurricane I’d like to be able to run a window AC unit, my refrigerator, and a few smaller items such as phone chargers and LED lights.  The AC and fridge were my big concerns since they’re the largest loads.  With this size generator I should be able to run both at the same time.  If both were to start at the same time it may overload the generator but I figure that is unlikely to occur.

As I mentioned in my last post, when anything containing a motor starts up there is a short time large current requirement.  This period of high current is called “inrush current”.  A the period of inrush current the current will drop down to near or less than the amount specified on the data plate on the device or motor.  My window unit lists the amps as 7.1 at 115V.  As my voltage is around 120 the running current will actually be a little less.  Power can the be calculated by multiplying the voltage times the amperage times the power factor.  Luckily, power is already listed on the data tag.  If the inrush current required by the AC is more than the generator can provide then it will kick offline and the AC will not start.

To measure the inrush current I used my Fluke 374 which has a special mode to do this.  When in this mode it will wait for a large spike in current,  take measurements for 100 ms, and then display the current.  Below is a picture of one of the AC start ups I analyzed.  Clearly, 30A is much larger than the listed 7.1A,  At 120V and 30A, 3600 watts  are required to start up the AC. For fun, I used my cheap current clamp and oscilloscope to show the  inrush current. Below is the startup of my AC.  The screen shot shows the current wave.  As you can see, after startup, there is a period of much higher current.  After this time the current then drops to the lower running level.  Also displayed are  two vertical lines which mark out 100 ms.  The values onscreen are calculated in this window.  The RMS value is 321.61 mV which converts to 32.1 A.  The values are not identical (probably due to several reasons I won’t go into) but are close enough for what I’m doing here.

The ability to provide increased output for inrush current is called “Starting Watts” on generators.  My AC needs around 3600 starting watts but the inverter generator only produces 2000 starting watts according to the rating.  When I try to start the AC off the generator it starts fine though.  When Eco mode is not turned on the generator doesn’t mind the AC starting at all.  If Eco mode is on then the generator slows a little before increasing RPM.  I’m sure the voltage sags when starting on eco mode but I haven’t measured it.  Maybe later…

Even though the numbers say my generator shouldn’t be able to start my AC, it does.  This is a good thing but it makes me wonder how the “Starting Watts” number is produced.  I looked online and in the manual but there is no mention of it.  I would think there should be a table in the manual that lists X number of watts can be produced for Y amount of time.  Since there isn’t it’s a buy and try thing which is unfortunate.  As far as I know, all generators are this way.

I was also worried about starting the fridge but it drew a much less amount of running and starting current.  Thus, I’m not discussing it as it is similar to what was shown above but with smaller values.

So far I have about 25 hours of time on the generator.  I runs well and I have no real complaints against it.  I did replace the spark plug with an NGK because some people have reported issued with the Torch brand plugs.  I’ve also never heard of Torch.  The instructions do say to slowly turn the choke off and I’ve found this to be accurate.  If the choke is turned off quickly the motor will stumble for a bit like any other motor.

Also, for those who may wonder I purchased the generator and it was not given to me to review.  But if HF wants to send me the larger version of this one I’d take it.

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Measuring Generator Fuel Consumption

Prepare for a bit of hack sciencing.  Since I live in a hurricane prone area I have a generator.  It’s a Generac 7550 running watts / 13500 starting watts standard open frame generator.  It’s always started, run well, and puts out power reliably.  My only complaints are that it drinks a lot of fuel and is loud.  That’s pretty much standard for these type of generators.  They consist of a gasoline motor driving an AC generator.  To generate 60 hz voltage the motor has to run at a little over 3600 rpm.  It does this when idling and under heavy load.

There’s a relatively new kind of generator out there called an inverter generator.  They use a gasoline motor to drive a DC generator.  This DC voltage is routed through an inverter to produce AC voltage.  As such, the motor doesn’t have to run at 3600 rpm.  Instead, it can adjust to provide the needed power and slow down when unloaded.  This paired with the smaller motors found in inverter generators results in them being quieter and more fuel efficient.  I was interested in getting one of these generators but wanted to be able to compare it to my current generator.   To do this I first needed to know the fuel efficiency of the generator I already own.  This is the subject of this post.

Here’s my current generator.  Please understand that I keep the generator in my unpowered shed and keep the battery inside my garage on a float charger 24/7.  When I periodically run the machine I just clamp the cables to the battery instead of fiddling with the tiny bolts.  Lazy?  Yes but it works fine.  If I actually had to use it in an outage I’d bolt the wires to the battery.

Now for the hack science.  In order to measure the fuel efficiency of the generator I need to be able to measure the fuel consumed.  While professionals might use a graduated burette or fancy electronics, I’m going to slap a gas tank on a scale!   But don’t worry it’s an old government postal scale which is reported to be pretty accurate.  My scale reads in increments of 0.1 oz which is accurate enough for this purpose.  The plan was to partially fill the tank which was hooked to the generator’s carbureator to run it off this tank.  I then ran the generator for 10 minutes taking weight readings at every minute.  I measured two load conditions: 0 and 1250W. This brackets my expected household loads in an emergency situation.  More on this in a future post. The unloaded condition is pretty easy to achieve but the loaded one had me looking around a bit.  I ended up using my electric smoker which was rated at the previously mentioned 1250W.  This has the added benefit of being a purely resistive load which means I don’t have to worry about real vs reactive power.  Note the little heater I had originally planned to use.  I’d forgotten it had a thermostat and would not come on in the outside temperature.

I also kept and eye on things with my Kill-A-Watt.  It confirmed the watts I was pulling.

Here’s the data I collected:

Load 0W Load 1250W
Minute Fuel weight (oz) Minute Fuel weight (oz)
0 69 14 57.9
1 68.1 15 57.1
2 67.3 16 56.1
3 66.6 17 55.3
4 65.7 18 54.4
5 65 19 53.5
6 64.2 20 52.6
7 63.4 21 51.7
8 62.7 22 50.8
9 61.9 23 49.9
10 61.1 24 49
Fuel burned 7.9 Fuel burned 8.9

As expected the loaded condition burned more fuel.  Since the fuel was measured in weight I need to convert it to volume.  To do this I can divide the weight by the density of gasoline which I found online to be approximately 0.426 oz/in3.  Also since amount of fuel burned in 10 minutes is not to useful I’ll convert it hours and days.

Doing the math I get:

Load 0W 1250W
Fuel consumption 111.27 125.35 in3/hr
0.48 0.54 gal/hr
11.56 13.02 gal/day

As you can see, doing nothing but making noise, the generator consumes about 0.5 gallons of fuel an hour or almost 12 gallons a day.  Loaded at almost 25% doesn’t really increase the fuel consumption that much.  Of course you wouldn’t run a generator 24 hours a day. But let’s say you run it for eight hours a day.  That’s still a minimum of 4 gallons of fuel a day or 28 gallons of fuel a week.  My neighbors had no electricity for two weeks after hurricane Ivan hit.

Inverter generators on the other hand get much better fuel economy.  For the most part, inverter generators come in approximately 1500W and 3000W varieties.  For example, a 1700 running watts Generac is rated run for 10.25 hrs at 25% load on 1.2 gallons of fuel.  A 3000 running watts Generac is rated to run for 8.9 hrs at 50% load on 2.6 gallons of fuel.

An inverter generator is vastly more efficient than a standard generator and much quieter if you can run within the 25%-50% running watts range.  On the other hand if you need more power and the ability to start hard loads standard generators are still your best bet.  Typically, the starting watts rating of standard generators are about twice the running watt rating while inverter generators only seem to give you a 400-500W difference.

More on inverter generators and a rant about starting watts in my next post.




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Wooden USS Baltimore: Part 3

In Part 2 I finished building the USS Baltimore. Now, in Part 3, it’s time for painting, painting, and more painting.

The first step was to spray everything with primer to make sure the paint adhered well.

My research online showed that the Baltimore spent its WW2 time in dazzle camouflage.  Specifically Measure 33/16D.  I also found some nice USN high quality pics of the ship at the Mare Island Navy Yard in California in Oct of 1944 at Navsource.  Online there was some text saying it went back to a more conventional paint scheme in 1945 but I could never find pictures to confirm it.  So dazzle camo it is.

Luckily, the official documents showing the dazzle pattern for this ship (and many others) are available online.   I printed them out to scale and then used them to sketch pencil lines on the hull.The hull has five different colors (mostly shades of gray): three on the vertical surfaces, two on the horizontal surfaces, and red on the bottom of the hull.  I worked from lightest to darkest color and started by masking the hull off.  Then I’d spray a color with my airbrush.  Then more masking and spraying.  I don’t know how many of these iterations I did but it was a lot.  Here are a few pics showing the process.

After FINALLY finishing the hull, I started on the super structure.  It’s shape meant I wasn’t able to tape as many things as I’d have liked.  Instead I used masking tape where I could and free-handed the rest with a brush. Then I worked on the big and medium guns.  The diagrams were a bit problematic for gun barrels.  The top view showed them at one color and the side view would show them at another.  As they’re round these both can’t be true.  So, I looked at the USN pics which showed them at the lighter color.Next ,came the support structures for the side mounted 40mm AAA guns.  There were some interesting patterns on them.As I was progressing, I realized I’d forgotten to make the Kingfisher float planes carried on the Baltimore.  I found a simple drawing of it and proceeded to scratch build a couple of them.  I roughly cut the pieces out on the bandsaw and then sanded/carved as required.  Tiny little buggers.I waited till near the end to put the masts and cranes on since I knew I’d probably just accidentally bump them.  I was not wrong.  Only a few more things to do now.Yay!  Finally finished and on deployment to the Tarpaulin Sea with the Fletcher (same scale).

Here’s a test for you.  Does dazzle work?  The Fletcher and Baltimore are both sitting out and I took some pictures from a distance.  Which way are the ships pointing?  Answer down below.

















Both ships are facing the same direction and at an angle about 40 degrees from the horizon with the bows closer to the camera.

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Wooden USS Baltimore: Part 2

After completing the hull in Part 1, it’s time to move on to the superstructure and guns.  My plan for making the superstructure was to print out the identification drawing at the scale I needed it.  Then, looking at both views, I broke the forward and aft superstructure into levels.  For each level I’d cut out a template and measure its height (or thickness for each piece of wood).  Below, you can see the forward superstructure’s six levels.  The number of levels may not match the actual ones on the ship but it’s a compromise between realism and reproducibility.

The templates were then traced onto 1/4″ thick wood to be cut out on the bandsaw.After cutting out the parts for the forward and aft superstructures, I temporarily put them in position on the ship.  Some of the parts were made of thicker wood and I still need to do some sanding on the rear exhaust stack.If you’re like me, you probably think WW2 battleships were big boats with big guns.  In actuality they’re floating anti-aircraft platforms with some big guns thrown on there too. It turns out heavy cruisers were built with the same idea in mind.  The Baltimore had 9 x 8″ guns (the big guns), 12 x 5″ guns (dual purpose surface or air guns), 48 x 40mm guns (air to air guns in groups of four), and 24 20mm guns (additional air to air guns).  The design principle seemed to be “If there’s an open spot stick some 40mm guns there.  If they won’t fit put a 20mm gun there.”  This isn’t surprising when you think of the primary threat at the time which were enemy aircraft.

I’m going to have 8″, 5″, and 40mm guns on my model.  I thought about trying to put the 20mm guns but they’re so tiny at this scale.  I started with the big gun turrets by cutting them out with the band saw.Then I drilled holes for the barrels.

To make the barrels, I trimmed down some nails.

The 5″ guns were done in the same way except I sanded them to shape.

Smaller nails this time.

The 40mm guns came two or four guns per emplacement.  The Baltimore had four gun emplacements.  The best idea I had was to make each emplacement out of a 1/4″ x 1/4″ square stick. Then I’d drill tiny holes for the barrels and cut slots into for detail.  To drill the tiny holes, I made a jig out of a piece of scrap.  

I made another “jig” for making the barrels.  Since the wire for the barrels was made from steel, I used a magnet to set the barrel length and then hold the barrels after cutting.

Next, it was time to assemble.  One of the emplacements has escaped in the pic below.

After I made all the guns I placed them on the ship to see what I thought.  Nothing is glued yet so I was able to tweak things as needed.

I then cut out a few more pieces for the aircraft related hardware.

About this time I started looking harder at the model of the USS Baltimore in World of Warships.  It’s much easier to see the ship in their 3D model than through old photos and drawings.  I found that some of the stuff in my drawing didn’t quite match up and there was some stuff I could improve.  From what I saw, I was able to make some new pieces for the superstructure that looked better.  Below is a piece for the front superstructure that replaces one of the original pieces.

I also replaced a few pieces that weren’t symmetrical.

Finally, I added some more details like the gun directors and some structures where some of the 20mm guns would have been.

I also started working on the masts.  I found it easiest to solder them as opposed to trying to glue the pieces together.At this point I’m largely done with building (though there are still some more details) and have started painting the ship.  Shockingly, it’s taking a while.

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Wooden USS Baltimore: Part 1

I’ve decided to make another wooden warship like my Fletcher.  This time it’s the CA-68 USS Baltimore from WW2.  This one will be in 1:350 scale like the Fletcher.  I wanted something bigger than a destroyer but smaller than a battleship and ended up with a heavy cruiser.   In real life she was about 673′ long by 71′ wide.  Here’s a picture of her from Navsource.

At scale my model will be 23″ long by 2.4″ wide and about 1.6″ deep.  This size is almost perfect for a standard pine 2×4.  Unlike last time, I’ll be using a softwood for the hull which is much easier to shape and lighter too.  Somewhere in the piece of wood below is the hull of a ship.  As a 2×4 is only 1.5″ tall I needed to add some more wood to the stem and stern of the ship where the deck rises.  After the glue dried, I trimmed most of the blocks off leaving material where I needed it.To start shaping the hull, I used a top and side view of the USS Chicago (another of the Baltimore class) from here.  Both the Chicago and Baltimore were turned into guided missile cruisers which radically reshaped the superstructure and armament of the ships.  I figured the hull was still the same which ended up being a mistake but that’s for a little later.   I scaled the drawings appropriately, printed them out, and taped them together.  Next, I cut them out and taped them to my block of wood.  Then I used the band saw to cut out the hull.  I cut the side view first and then the top which kept me from having to tape pieces back on after the first cut.

I used my stationary 4″ wide belt sander to turn large amounts of the wood into saw dust and shape the hull.  To profile the bottom of the hull I used some of the body plan lines that were included in the general plans.  I cut the available lines out after printing them on card stock and marked their locations on the top of the hull.  I then alternated between sanding an area and checking its profile.  Once I had all the areas close to shape, I blended the hull and hand sanded the entire hull down to 240 grit.  The hull’s shape is pretty close except for the front quarter of the ship which has a concave shape to the sides of the hull I was unable to duplicate with my method.      

After all the sanding I finally had a boat hull.  I next turned my attention to the superstructure and started looking for pictures of the ship.  The Navsource site had numerous good photos including one of the stern…that looked much blunter than mine.  It turns out they did reshape the stern in the conversion.  I looked for more plans but was only able to find a basic identification drawing of the ship which was probably ok for its purpose but not great for mine.  It’s all I could find though.  Below shows the stern of my boat along with the drawing.  Note that the stern still ended in the same spot but I’ve moved my ship some to show the aft end of the ship in the drawing. 

After all the work I’d put into the hull I didn’t want to chunk it.  After thinking about it a bit I decided to cut off the back of the ship and attach block to correct my issue.  Since this is end grain to end grain gluing, I drilled holes for dowels to reinforce the joint.

Once the glue had set for a few days it was back to the sander for more saw dust creation.

After all that I finally had a complete hull.Up next, I’ll start work on the superstructure where I’ll learn to dislike the identification drawing even more and learn just how many guns this ship had.



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