Ball Hopper Monitor - Casting Project

GreenTwin · Dec 15, 2024

I recall starting the BHM flywheel, and had two different attempts to get the spokes looking approximately correct.
I did not get the flywheel as far along as I thought.
That is the problem with getting on and off of a project; it is easy to forget where you left off.
I could fix this flywheel, but I think I would rather have it as a generic 5-spoke flywheel pattern half, for some other engine use.

I have some work projects I need to focus on, so I will have to pause the printing for the moment.
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GreenTwin · Dec 15, 2024

Not a bad start for now.
Not really what I want it to look like in the end, but a good start.

The bed adhesion on the XL is most impressive.
I struggled to get this print off the bed.
This printer absolutely does not need any draft shields, enclosure, etc.

I have a large window air conditioner that blows cold air directly onto, over and around the XL, and there is absolutely not adhesion problems caused by this.
There is no way my old Prusa MK3 would ever be able to do this.
It was very draft sensitive, and the bed adhesion was almost always poor.
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GreenTwin · Dec 15, 2024

The fumes generated by 3D printing PLA filament are pretty minor, but after printing a number of parts over a matter of days, my eyes are starting to burn.
I can't detect an odor, but I am going to need to ventilate the Prusa XL to the outdoors.

For now I will make a simple box, with door, and use an inline fan to draw air to a vent mounted on the outside wall.

I will use a solid top, and mount the filament reels on the top.
If this works, I will consider building a more elaborate enclosure, but I don't need or want anything fancy.
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GreenTwin · Dec 15, 2024

They have some printable enclosures for the XL, but I don't really need plexiglass walls, since plexiglass is not really inexpensive.
I have some small square metal tubing that I think will work well, and then some 24" translucent stretch wrap will get me going for now, and if I want to add plexiglass later, I could do that.
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GreenTwin · Dec 15, 2024

I have to get ready for a work project tomorrow, so no time to get involved in the details of the remaining patterns at the moment.
Just for fun, I will place some parts on the printer and print them.
I need to refine the 3D models for these a bit more for patterns, but we will test the multi-part print today.
I suppose that if the print fails, you lose all the parts at once, but it would be nice to print multiple prints at the same time.
I don't recall trying a multi-part print before, so here we go.
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Jasonb · Dec 15, 2024

Pat have you given any thought as to how you will fit and do up the conrod bolts?

There is a reason the original engines had a hinged big end and that access panel on one side of the crankcase.

Even if you are going to use that conrod what happens when you saw the cap off as you have not elongated it to allow for the kerf of the saw and clean up.

Also why print things like screw holes and the piston grooves. Talking of the piston what about a chucking spigot so it can all the critical bits be machined in one setting

Seems some more design work is needed as I said a few days ago before you waste more filament.

GreenTwin · Dec 15, 2024

I have some old filament that is borderline brittle, and so I want to use it up before it becomes totally unusable.
Today is just a fun print day.
No time lost since I just watch it.
I have to work on a work project today, so no time to tweek these parts like they may need.
All these pieces need to be converted to patterns, and that has not been done yet.

I will have to revisit the conrod; I think you are correct on that.
The conrod and crankshaft would be good candidates for ductile iron, if I can get my reaction chamber finished.

This is fun print day, nothing serious.
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Jasonb · Dec 15, 2024

Must have been the file names that made it look like they were patterns

GreenTwin · Dec 15, 2024

This is a sit back day, grab some coffee, and for me, work on a project that has a conference call tomorrow.
The serious pattern work will have to begin again next week.
There is no rationalizing a fun print day; it is just for fun.
Basically these are desk ornaments, but it is nice to have something in hand to get a feel for the parts.
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GreenTwin · Dec 15, 2024

Progress photo.
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Edit:
It is good that I ran a test print on these items.
The 5% fill is not enough for smaller parts with small shapes, and so some of these items basically have almost no infill.
A reprint of these I think needs at least 20% infill.

We can also check the supports for these parts.
I am not sure the supports on the piston will be easily removeable.
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GreenTwin · Monday at 3:16 AM

Several problems have emerged in this multi-part print, as follows:

1. I used "supports everywhere", and the supports are so dense that they are very difficult to remove from several of the prints.
I have watched a video about how to adjust the distance between the print and the support, and I need to determine what a good number is to stop the over-adhesion of the support to the print.

2. The 5% infill works well on the larger prints, but for small prints like these, the infill is spread so wide that essentially you end up with little or no infill.
Even with almost no infill, these parts are pretty strong, but for parts this size, I will increase the infill to 20%, since I want the exterior surfaces well supported.

The orientation on the print table, ie: up or down, seems ok for these prints, if I can get the support adhesion issue worked out.

I am not sure if the multi-print method was an advantage, or whether it saved any time.
One possible scenario is if the print failed for whatever reason, you lose multiple parts instead of one.

This was a good test.
I definitely learned a few things with these prints.
I still need to modify these parts into patterns before I attempt another print.
Bed adhesion is still excellent on this printer; a huge improvement over the MK3.

The multi-colors are a result of me using up old rolls of filament that were almost too brittle to be used.
The PLA seems to regain its strength after being run through the extruder.
PLA printed patterns will eventually become brittle, so be aware if you plan on using them over an extended period of time.

If I were using the investment casting method, I would leave the holes in the patterns.
For sand molds, the holes would have to be created using graphite rods, and that would almost certainly cause a mis-fill.
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Jasonb · Monday at 3:44 AM

I am not sure if the multi-print method was an advantage, or whether it saved any time.

You should be able to work that out easy enough. The slicer software gave the print time for the group so just use the same settings and see how long each individual part would take, add them up and see if it is more or less time. At least then you will know for future prints which is the quicker.

GreenTwin · Monday at 4:03 AM

My main concern is bed adhesion, and that is not a problem with the XL printer.
I had a lot of bed lifting problems with the MK3, and that is a show stopper; you can't make patterns when the pattern pops off the bed before the print is complete.

I sliced the outer muffler part, and it is a 4 hour print, so the print time is the sum of each individual part print times apparently.

The advantage of a multi-print is you can put the parts on the printer at the same time, and assuming all goes well, you can leave the printer unattended (assuming you have plenty of filament loaded), and come back 15 hours later with everything printed.
If something goes wrong, you lose all the parts.

So far I am pleased with how the 3D printing is going.
These parts need more work, and their printer settings need to be tweeked, but we will get that worked out.

There is no sign of the airbrush yet, so it may be stuck in the holiday shipping rush.
Edit: Tracking shows that it is in this city, to be delivered in the next few days.
I have never used an airbrush, so somebody will have to give me the 30 second lesson on what to do.
I guess it is just a mini-paint sprayer, but I am not sure how to vary the spray, or what other features it has.

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Jasonb · Monday at 4:30 AM

Use the one at the bottom which is an external mix type and the only one that may handle the coarse "pigment"

Mix wants to be like thin cream towards milk so probably too wet to be of much use, avoid any lumps

Amount of paint flow is done by twisting the conical part coming up at an angle from the bottom

Width of spray is determined by how far away from the part you hold the gun.

25-30psi on the compressor regulator.

GreenTwin · Monday at 4:58 AM

I envision the thinned fastpatch as having the consistency of slightly thick latex paint.
You can spray latex onto a vertical surface right up to a point, and then it begins to run, so I think the trick will be to get an even coat of fastpatch sprayed on that is thick enough to cover the irregularities, but thin enough to require only light sanding and not run/sag.

I am not sure if it will try to chip off or not.
Lets hope not.
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Jasonb · Monday at 5:10 AM

Here latex (emulsion) paint is sprayed with airless sprayers which is a completely different approach.

Fidlstyks · Monday at 8:41 AM

I was talking wuth a neighbor who said that his nephew can scan and print a whole person.
He scanned and printed this hog oiler, and he said he did the main body in 20 minutes, I was thinking you said 18 hours.

GreenTwin · Monday at 8:53 AM

I have not gotten into scanning yet.
I have considered it for some of my work projects, but a 3D model is of limited use for a project that really needs floor plans to scale, and elevations/details to scale.

At any rate, the scanners I have seen are very quick, scanning an object in just a few minutes, depending on exactly which scanner is used.
You can scan entire rooms/buildings, etc.
It is an impressive technology, but so far I have not found a practical use for it in the design business.

From a modeling standpoint, I suppose a full sized engine could be scanned, and then those images reduced.
I think an old engine would really need to be scanned piece by piece.
And one drawback of a scanned image is that it produces a surface-mapped entity, which may not be easily edited.

That is an impressive casting, but I have to ask, how exactly does that work ?
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Fidlstyks · Monday at 1:30 PM

I see I was going to ask you how you program your 3d printer, and assumed you scanned, and was asking you.

Something was said to the stating he has a wand of sort, and moves it around an object, and prints it in plastic or a chemical metal or fiber as you see it.
And he can make it elongate for shrink, an machining amounts.

GreenTwin · Monday at 2:14 PM

I start by studying photos of original engines, and in this case getting someone to measure his 4hp engine.
I also used some information from prints from the original Baker engine brochures.
I rough out the geometry in AutoCad, in 2D drawings.
Then I pull in the 2D sketches from Autocad to Solidworks, and convert those to 3D models.
Solidworks can save a model as an STL file, which can be read by the Prusa Slicer program.
The Prusa Slicer program creates a G-code file that I transfer to the 3D printer via a flash drive.

So that is how my designs make their way from photos into 3D printed patterns.
Everything originates either from dimensions taken from a full sized Baker Ball Hopper Monitor engine, or from the original Baker engine brochure.

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Ball Hopper Monitor - Casting Project

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