Ball Hopper Monitor - Casting Project

[Fidlstyks]

The Monitor uncovered showing inside releif cutouts for counter ballance.
The base for when not on the sawrig.

 

[GreenTwin]

Great photos !
There are very few photos of Ball Hopper Monitor bases.
It is interesting to see all the variations in these engines.
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[GreenTwin]

The first gas tank pattern half print is complete.
The logo was tricky because it is not directly on the front of the tank, but is up a bit.

I dialed the layer adjustment up to the highest setting, and the print time was not too excessive (9 hours).
The print quality I think is very good, not great like a resin printer, but a very respectable quality I think, and quite usable.

The photos are zoomed in a bit, and the light is sometimes cast to maximize the constrast on the lines, but the lines are small, and it would be simple to fill this pattern.
The lines are hardly visible when viewing this print from 24" away.

I am please with this print.
I will have to study JasonB's info about variable layer height, since I think that would have been a good thing to use on the water hopper, since I increased the layer height on that print to decrease print time.
I think the variable height function also increases print time, but apparently not excessively.

I will study the variable height info, and if it is not too complex, then I will incorporate that in the 2nd print half.
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[GreenTwin]

I played around with the variable height options in the Prusa Slicer program.
Not sure I completely understand what is happening and why.

There is an "Adaptive" button.
A "Quality/Speed" slider.
A "Smooth" button.
A "Radius" slider.

When you select variable height, the dialog box appears on the lower right of the screen.
A vertical profile appears on the right side of the screen.
The colors on the vertical profile correspond to the colors displayed on the model, but I don't understand that either.

I played around with different slider settings.
And apparently you hit the buttons repeatedly.
As you hit the buttons, you can watch the profile change on the right side.

I played around until the profile on the right was as flat as I could get it.
Did I get the settings correct ?
Not sure.
I will try a variable height print of the 2nd half of the gas tank.

Looking at a side-by-side comparision of the non-variable height sliced part and the variable height sliced part, there does appear to be some differences in the image.

I can compare the 1st and 2nd gas tank half prints, and see if the variable height adjustments helped obtain a smoother surface.
It will depend on whether I am making the correct interpretation of what the variable height adjustment is doing.

Using the variable height function reduced the print time by 3 hours, so I don't understand that.
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[Jasonb]

I've only looked into the BambuLabs one but it is the same principle

This guy explains quite well what the different colours and the graph down the side mean.

Taking your image 35 the light areas are where it has reduced the layer height as it goes over the crests of the filler boss and then again goes light on the crest of the main tank. These are the areas where you would get a more noticeable horizontal spacing between the contours of each layer so the software adapts the heights in those areas to reduce the spacing.

As it only reduces heights in certain areas most will still print at a faster 0.2mm height so it is faster than setting it to your lowest height but takes a little longer than if you did it all at 0.2mm

 

[Jasonb]

You don't see many bases because most of the engines had the feet cast as part of the crankcase, only a few had the separate base. If you look closely at the photos you will see that the crankcase has the mounting lugs just below crank shaft height and that is also why the base has the cut outs so that it will clear the lower part of the crankcase which drops inside the separate base.

It is not like your freelance base that fits to the bottom of the cast feet making the engine top heavy.

 

[GreenTwin]

I am watching the 2nd gas tank pattern half print.
My PLA filament was purchased a few years ago (I forget exactly when; time flies), and so some of it has become brittle.
The Prusa XL has a pretty long filament feeder tube, with two 90 degree bends, and then a large 180 degree bend.
The tube is not generously sized.
My filament began cracking inside the tube, and cracked PLA is not easy to get cleaned out of the tube.

I ended up unscrewing the tube from the print head, and suspending the roll over the printer.
The filament now drops down vertically directly into the print head, and the filament is strong enough to do that without cracking.

I could purchase new PLA, but I purchased a number of rolls, and so I need to use those up and not waste them.
PLA is pretty reasonable in cost, at least it was a few years ago.
Nothing is reasonable these days.

While watching the print progress, I ran across an iron bowl manufacturing video, which is perhaps the thinnest iron I have ever seen cast.
I would consider it more of an injection-molding process.
Makes a super thin cast iron cook surface.



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[GreenTwin]

I tried the Variable Height option in the Prusa Slicer, but I can't tell any difference from the first gas tank half print.
I am not positive I used the Variable Height option correctly.
It may have defaulted to a more coarse setting.

Print turned out usable.
I forgot to use supports, but the print is still usable.

You can really get a feel for the size of a part when you can hold a 3D print in your hand.
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[Fidlstyks]

You don't see many bases because most of the engines had the feet cast as part of the crankcase, only a few had the separate base. If you look closely at the photos you will see that the crankcase has the mounting lugs just below crank shaft height and that is also why the base has the cut outs so that it will clear the lower part of the crankcase which drops inside the separate base.

It is not like your freelance base that fits to the bottom of the cast feet making the engine top heavy.

I am quite certain the subase was only used on the 6-7 hp engines. Perhaps for casting-assembly ease, or to make them fit the buzz saw rigs.

 

[GreenTwin]

Moving on to the flywheel.
I removed the draft angle from the rim, and am going to mold that flat, using a mylar strip.

I scaled the flywheel to 14" diameter, which is not exactly 1/2 scale, but is as large as I can print.
I don't think anyone would pull out a tape measure when they see the engine, other than perhaps JasonB, but he is over there...........and I am over here..............so there is that.

This is a 21 hour print, and I am hoping that since this flywheel is symmetrical, I can use one 3D-printed pattern half to cast two permanent aluminum pattern halves.
I will have to baby this pattern when removing it from the mold.
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[Jasonb]

Don't need my tape measure to remind you that you have not modeled the hub clamp even if it is going to be a dummy it is quite a prominent item and easy to spot.

Also you are going to need one half with the boss, stop pin and spring lug for the governor together with the pulley mounting bosses, again prominent features and you can't do without the governor. Which I think will also mean the halves on that side of the engine are not symmetrical.

Finally what are you going to do about teh balance grooves, they were not the easiest to machine on my 9" flywheel so will be harder on a 14" one and if being true to original you want to be casting these in rather than machining them. Different for each side.

 

[Jasonb]

You have also left yourself quite a bit of machining to do, if you had cast it with the raised narrow edge to the rim you would only need to machine that both sides plus the face. As you have the pattern now you will have to turn the "cast" surface so it is narrower than the rim and then blend that into the rest of the flywheel.