Ball Hopper Monitor - Casting Project

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Almost as easy as cutting gears but you bought those.

If you are going to make your own rings then may as well just size them to suit the scale 2.140" bore
2.125" bore is a more standard size, so I will go with that.

Rings are much easier to make than gears, since you don't need to set up the indexing head, and don't have to figure out the blank size and setback on the cutter.
I can do gears, but I have not done them yet, and I would probably fail on the first few attempts.

I have made a number of cast iron piston rings in the past, and I have that down to a science, and can do that quickly.

I cut them a thou or so on the thick side, and then slowly work them down to size on emory cloth, checking the make sure they fit along their entire length by rolling them through the slot in the piston.

I have ring charts that give a good starting point for the dimensions of a range of ring sizes.

And MEB sent me the article they published on how to make the ring oversized, remove a section, compress the ring on a mandrel, and then turn it to final size.

I have been making rings to match the bore size, and then springing them open and heating them, but I did get a little distortion last time I did that, and so I want to start using a non-heat method for making rings.

I have a digital vernier caliper attached to my lathe carriage (poor man's DRO), and so it is easy to repetitively cut off rings at a consistent width.

I suggest you consider a bore that matches the many available rings for small engines/scooters etc. They are cheap and plentiful. If you make your own you can make them that size and if unhappy buy commercial rings. Most are metric sizes. I have been especially impressed with Honda 4 cycle rings that have a very nice oil control ring, probably not a consideration for a hit and miss engine however.
There are a lot of valid reasons to use existing items, and you can save a lot of time doing that, such as what I did above purchasing the gears.

One the other hand, I am a stickler for making scale engines that are as close as possible to the original engine, both inside and out, and including draft angles, surface finish, fasteners, etc.

On my first and only completed engine (see avatar), I made all of the fasteners, because the modern fasteners don't look like the old fasteners.

If possible, I like to be able to take an model engine apart, take close up photos of the parts, and then compare them with photos of full sized engine parts.
I don't like to be able to see any visual differences between the scaled and full sized parts, and I like it to be impossible to tell one from the other.

This is the goal when I build an engine.

Much depends on how much information one can find on any give engine.
If I happen to have an actual engine on-hand to dissassemble and measure, then I can basically make a smaller carbon copy of the original.

If I only have photos of the original engine, such as was the case with my avatar engine (I had 3 photos only), then I get as close as possible using superimposed grids in CAD, and close visual comparisons. You can make a model that is surprisingly close to the original just by using photos, but as the engine gets more complex, it becomes more difficult to see small parts, and difficult to figure out how all the small parts interact, such as on an IC engine.

I have found a few photos of partially disassembled Ball Hopper Monitor engines, but there are very very few of those, and what they show is not the complete engine, but rather bits and pieces.

I have a good set of photos from JasonB's ball hopper monitor build, shown here:
This is the exact engine that I am trying to model, and so Jason's work is very useful.
This was a Pacific Model Designs engine.
The Pacific BHM seems to be very close to the original 4hp engine, but as I study photos, and things, I notice small diferences which I think were overlooked.
The photos of the full sized 4hp BHM that I have show the spark plug on the left side of the valve chamber, and a priming cup on the front.

There is a slight diference in the cover that is on top of the hopper, comparing the model with the full sized engine.

Most folks would never notice the small details, and most folks are not concerned with small details that most would probably never notice, but if an original engine had certain details in the parts, then a clean re-model of that engine should have those details, at least that is the way I like to do it.

Water jackets almost never get cast into the block or head, but if I have the ability to cast those, why not include them?
Complex cores are not that difficult to make when you can create multi-piece 3D-printed coreboxes.

The older piston rings tended to be wider than modern rings, especially on steam engines, and I always match the original width of the ring.
People say "Nobody will ever see the rings", and that does not matter, because it would bother me to have thinner rings than the original.

One guy laughed at me at an engine show when I told him I like to cast my own engine parts.
He pulled out his smart phone, and in 60 seconds showed me his favorite supplier for flywheels, and a whole host of other pre-built engine parts.
So he is in the hobby for different reasons than I am, and he basically assembles parts that others have made.
All fine and well depending on what you like to do, but as I told him, you can't buy parts that exactly match the old engines.
"Close enough for him", and I said "not for me". Different strokes for different folks; it is all good.

I did purchase the oilers for the green engine I made, because they were very small, and my attempts to make them did not turn out well.
I am not good at making watchmaker-grade-size tiny parts.

For this Ball Hopper Monitor, I purchased the gears since I really needed to start with a known item, with known dimensions.
The entire engine design could be upset if the gears don't fit.
Since I am going to design the entire engine outwards around these gears, I really need to have an exact thing to start with.
I think I can make these gears look very close to the original BHM gears, although I think the original engine had the cam and gear made as one piece.
I will have to attach my cam to my gear, but it will not be a very noticeable thing.

I do have gear cutters and an indexing head, but it is not about if I can or cannot make gears, but right now it is about getting a good design completed in 3D modeling, so I can start 3D printing patterns.

The 2hp Ball Hopper Monitor has a 30/60 tooth gearset, and I think the 4 hp engine may also have a 30/60 setup.
I don't have a good enough photo of a 4hp gear to count exactly, but it does look like 30/60 teeth, best I can tell.
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Another Ball Hopper Monitor Build I ran across is the one by Myfordboy.

I suspect his engine is also based on the 4hp BHM, but I am not positive.

Myfordboy's build is interesting in that he created his own patterns from scratch, and then cast his own parts in aluminum.

I want to cast all of my parts in gray iron, and I want a scale that gives 12" flywheels and a 2" bore.
The BHM casting kits that I have seen all have 9" diameter flywheels.

Here is a link to Myfordboy's Ball Hopper Monitor casting videos:
He is very good at casting aluminum.

I vary a bit from how he does things in his sprue/runners/gating/risers.
He casts his fuel tank in three pieces for some reason.
I will be casting a one-piece fuel tank, just like the original.


A few notes on the last video:

1. You should never stir an alumium melt.
You are just entraining gas, slag, etc. into the melt.

2. Washing soda does not degas aluminum.
The bubbles you see are from moisture in the washing soda.
If you bake the washing soda completely dry, you will get no reaction at all when you add it to aluminum.
If you heat aluminum quickly, and pour immediately when you reach pour temperature, then you generally don't need to degas.

3. Myford likes to gate right into the flywheel rim cavity, but he gets a bit of distortion from high velocity there (see 19:48).
If you do gate directly into the flywheel rim cavity, it is best to do it where he does it, which is at a spoke.
I prefer a runner around at least 1/2 of the flywheel cavity, with multiple gates, to control the velocity.

Trying to fill a large mold cavity through a small gate often leads to defects, and that is the most common mistake I see backyard casting folks make.

I follow most of John Campbell's methods for casting aluminum and gray iron.

I have had conversations with some backyard casting folks who don't follow John Campbell's 10 rules, and they say "See, my casting is fine and I ignored all of the rules".
To some extent this may be true, but I can get visibly better casting quality, and reduce casting defects to basically zero if you follow John Campbell's methods.
For those who have purchased castings for engines, some may be superb and flawless like the ones Lone Star use to sell, or some may be full of blow holes, inclusions, hard spots, and be very distorted in shape and size (I will withhold the names of the casting suppliers that I have purchased from that sell terrible castings, at least as far as the ones I recieved; I don't think they still are in business).

My rules are:

1. Make one mold, and get a high quality casting very time.
2. No hard spots (chills).
3. No sand inclusions.
4. No shrinkage.
5. No hot tears.
6. Very accurate casting dimensions that are near net, ie: it only requires a light skim machining pass to get them to the finished size.
7. Round castings should come out of the mold round to a high tolerance, and should not wobble when chucked into a 3-jaw chuck on a lathe.
8. No entrained air, or high velocity defects.

It is easy to make consistently high quality castings if you pay attention to John Campbell's methods.
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One source shows a pretty wide exhaust cam, but other's have used a relatively narrow cam peak.

Does anyone have the exact original factory 4hp timing for the exhaust valve?

I found this thread.
Lots of good information here; I don't know what it means, but lots of good information.
I have spent 10 years (+) studying valves on steam engines, specifically the D-valve, and I have a pretty good handle on that I think.

For gas engines, I have toyed with and rebuilt lawnmowers for a long time, but I always took the cam shape and lift for granted, and never paid much attention to it.

I have followed along with hot rod car engines for a long time, and am somewhat familiar with lift and duration.

Obviously the Ball Hopper Monitor will not be a hot rodded engine.
I would like to match the original 4hp cam profile and lift, if I can figure out what that looked like.

I am going to have to deep dive in IC cam design and timing Lesson 101, because I just have a vague notion of how it works.

I studied the Frisco Standard cam, but did not reverse engineer it.

I reverse-engineered a Stanley D-valve and its eccentric, and plotted the valve travel vs ports in an Excel spreadsheet.
I am not sure if that is a good approach for the Ball Monitor engine or not.

From a video in the link above, it looks like a dial indicator will be useful in setting up an IC engine timing.
I do have a dial indicator.

I will see if I can get the right terms fixed in my head, such as BTDC, ATDC, etc.

I found this cam shape, and supposedly it was in a Baker notebook.
Not sure exactly which engine this referred to, but I suspect it may refer to a ball type, and I am not really sure what this diagram is telling me.

Some of the Baker engines had a cam lobe for the intake, but I believe the Ball Monitor intake valve is just spring loaded, and not actuated by a cam.

As I read the diagram below, but I have no idea what this means, and so quite likely I am misunderstanding:

Exhaust Opens: 36 degrees before
Exhaust Closes: 3 degrees after

Inlet Opens: 5 degrees after
Inlet Closes: 8 degrees after

I would guess that the exhaust valve would open 36 degrees before bottom dead center BBDC ?
And the exhaust valve would close 3 degrees after TDC ?

Intake valve would open 5 degrees after TDC, and close 8 degrees after BDC ?

These are wild guesses.

For the Ball Monitor, we would only be concerned with the exhaust valve, since it is the only one actuated.

Assuming intake and exhaust are actuated, then if the exhaust valve closes at 3 degrees after TDC, and the intake valve opens at 5 degrees after TDC, then there would be a short period near TDC when both valves are closed.

And if the intake valve opens at 5 degrees after TDC, and closes 8 degrees after BDC, then that is the intake stroke, pulling in fuel and air.

The piston then rises and compresses the fuel/air charge, sparking I guess a little before TDC.
I think there is another cam somewhere that actuates the ignition points (assuming an old-school points system).

The expanding charge pushes the piston down, and then the exhaust valve opens at 36 degrees before BDC.
The piston rises and pushes out the exhaust gas until the exhaust valve closes at 3 degrees after TDC.

This is how I read it, check me on this.


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Looking at the 1 7/8 x 2 Breisch Olds drawings, we have the following:

1. Engine fires when piston is 12 degrees before top dead center TDC.

2. Exhaust valve opens 35 degrees before bottom dead center BDC.

3. Exhaust valve closes 5 degrees after top dead center TDC.

The Olds drawings below don't seem to match this data exactly.
I see the exhaust valve closed at 2 degrees after TDC.

This is close to what is listed for the Ball Hopper Monitor above.


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One the other hand, I am a stickler for making scale engines that are as close as possible to the original engine, both inside and out, and including draft angles, surface finish, fasteners, etc.

Kind of contradicting yourself a bit already Pat, if you want it exact then why choose a set of gears with an non scale PCD and probably pressure angle, Why say you will make the flywheels with wider rims, why round up the bore size, etc

I believe Myfordboy had access to a set of drawings for the PMD engine when he made his own

Most of what you will read on cam design is for faster running engines and with the atmospheric inlet it will always open some time after the exhaust has closed as it needs a vacuum in the cylinder to suck it open. Wait until you try the small VJ with it's two lobed cam that just works the exhaust and be glad Baker did not use ignitors!
I guess you key the smaller gear to the crankshaft in some random spot.

The flywheel recesses in the rim would have to be 180 degrees from the crank rod end.

The large gear would have to mesh with the smaller gear to give the above exhaust vavle timing, which means I guess the if the cam lobe was adjustable on the shaft, at least during construction, it could be adjusted to give the correct exhaust valve timing events.

Kind of contradicting yourself a bit already Pat, if you want it exact then why choose a set of gears with an non scale PCD and probably pressure angle, Why say you will make the flywheels with wider rims, why round up the bore size, etc
I am always absolutely consistent in my choices, except when I am not.

One has to pick and choose one's evils.
I think we all do that to some extent.

The wider rims are a visual thing, to make the engine look slightly more like a diesel flywheel.

Just my preference, and yes a deviance from the original.

I think it would look better with a slightly wider rim.

I assume the original BHM gears were 14 pressure angle, and the ones I purchased are 20.
They did not offer the correct size and ratio in the 14 gears.

I am not sure the Pacific model gears are the same as the original, and I am not sure if they are scaled correctly either.

The 2 hp is definitely 30/60.
That can be clearly seen on the cut sheets.

At any rate, I would assume the gears would be easy enough to change if desired by someone else ? or not ?

The original Alan Shelley drawings for the 1/3 scale Galloway show a cam with dimensions, but I don't see where they spell out the exact exhaust valve open and close points.

This cam profile has a broad flat top.

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