I've been seeing a lot about glues and finishes that harden when exposed to UV. I wonder if there is any product there that might work for you? Enjoying the ride and looking forward to some metal casting!
Ball Hopper Monitor - Casting Project
- Thread starter GreenTwin
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It is possible that something like that could work.
I guess the plus side to using something like sheetrock joint compound is that it is inexpensive, and readily available anywhere.
Water-based cleanup too.
I am ready to moving on to some casting work too.
Pattern filling is probably my least favorite thing to do.
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I am not sure whose picture this is, but this is how I plan on making my Prusa printer enclosure.
The inline fan should arrive today.
Crude, yes I know; there will be some here most unhappy with the crudeness.
No time to build an award-winning enclousure; I have printing that needs to get done now.
I have some 1/2" steel square tubing that will work well in lieu of tree branches, you will be glad to know.
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The inline fan should arrive today.
Crude, yes I know; there will be some here most unhappy with the crudeness.
No time to build an award-winning enclousure; I have printing that needs to get done now.
I have some 1/2" steel square tubing that will work well in lieu of tree branches, you will be glad to know.
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Dumb question but have you tried & dismissed a decent quality high build primer in a spray bomb? No gun, no mixing, no compressor, no cleanup. Just rattle & shoot. There are all kinds but if you go to an auto paint store you will have the best luck finding one that fills & flashes quickly for recoats. Even different colors/tones so you can use that to your advantage. I'm positive it is going to fill & sand better than any spackling compound, that's what its engineered to do. Think about the environment a typical car part or plastic based fender is going through its life. Especially compared to a water based spackle that is bound to have a hard time bonding on plastic. If you consider the tools used to spread patching compound, they are arguably a similar plastic as 3DP filament from this standpoint & are intended to be cleaned & re-used. Often you just have to bend it slightly & the dried spackle just lifts off.
The problem with activated CA glue or UV epoxy or anything like that is you are putting a rather uniform layer over the hills & valleys. So yes some is getting into the valleys which is 'fill' but its your job to sand & conform all the mountain tops. Because these glues cure hard (much harder than 3DP), that is making a lot of extra work to then sand & you are likely deviating from the base shape. CA can be purchased in a range of viscosities from water thin to honey thick but you have to essentially paint it on which is not so easy. Epoxy resins are typically thicker viscosity. Now you may want a hard shell for those reasons but sounds like you just want a good surface with minimum fuss & maximum turnaround time. IMO that is the domain of primers (or spot/glazing fillers if the grooves are deep enough to warrant).
The penmaking folks use CA glue to finish wood or other materials. Here is one I did. I was actually kind of amazed because I've always thought of it as just an adhesive. But it requires many layers & intermediary sanding. And the application is not exactly easy to get it on in a controlled manner.
The problem with activated CA glue or UV epoxy or anything like that is you are putting a rather uniform layer over the hills & valleys. So yes some is getting into the valleys which is 'fill' but its your job to sand & conform all the mountain tops. Because these glues cure hard (much harder than 3DP), that is making a lot of extra work to then sand & you are likely deviating from the base shape. CA can be purchased in a range of viscosities from water thin to honey thick but you have to essentially paint it on which is not so easy. Epoxy resins are typically thicker viscosity. Now you may want a hard shell for those reasons but sounds like you just want a good surface with minimum fuss & maximum turnaround time. IMO that is the domain of primers (or spot/glazing fillers if the grooves are deep enough to warrant).
The penmaking folks use CA glue to finish wood or other materials. Here is one I did. I was actually kind of amazed because I've always thought of it as just an adhesive. But it requires many layers & intermediary sanding. And the application is not exactly easy to get it on in a controlled manner.
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That is a shockingly good finish on the pen.
Learn something new every day.
I have had some suggest using the high-fill auto spraypaint, but I am going to stick with a water-based product, since I want to use it in my office, and I want the ease of water cleanup.
And one benefit of water-based filler is you can put a hair dryer on it and dry it quickly; within minutes.
I am trying to do all the 3D printing, filling, and sanding in my office, since it is cold outside in the shop/shed, and I don't want to turn on the electric heat out there, since that makes the meter spin like a top.
Since I will use the 3D printed pattern only once (hopefully), I only need it to make one mold, which will be used to make an permanent aluminum pattern half.
So the hope is that the filler will stay on long enough to make one mold.
I am going to spray on an overcoat of shellac over the filler, and that sort of holds it the filler together for a while, and prevents most chip off temporarily.
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I have contemplated several casting options.
One idea was to use a small kiln that my next door neighbor owns, and melt aluminum in that, inside my office (I don't recommend anyone do this).
One problem with a slow melt is hydrogen absorption, and while many/most would not notice the pinhole porisity, I do notice it, and don't care for it.
It is winter here, and so in the 30's today.
I really want to set up my iron furnace, and use it for both iron and aluminum melts.
20 lb aluminum melts are 12 minutes from a cold start with my iron furnace, and that generally prevents hydrogen absorption.
A bigger problem is making molds in cold weather.
The temperature affects the set time, etc., and the sand may not set correctly.
In order to make molds, I am going to have to turn on the heater in the shed.
The sand needs to be some reasonable temperature too.
Once the mold is made, a carboard box has to be placed over it, with a hair dryer heating the air inside the box.
If the mold is cold, it will cause a partial fill.
If I don't do a winter pour, the danger of waiting for warm weather is I will get too detached from this build and lose momentum, and chances are I will get too busy with work projects too.
Now is a good time to do some aluminum pours, so I need to do a winter setup.
I could probably put some sand in an old cooler, and put a light bulb in there.
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One idea was to use a small kiln that my next door neighbor owns, and melt aluminum in that, inside my office (I don't recommend anyone do this).
One problem with a slow melt is hydrogen absorption, and while many/most would not notice the pinhole porisity, I do notice it, and don't care for it.
It is winter here, and so in the 30's today.
I really want to set up my iron furnace, and use it for both iron and aluminum melts.
20 lb aluminum melts are 12 minutes from a cold start with my iron furnace, and that generally prevents hydrogen absorption.
A bigger problem is making molds in cold weather.
The temperature affects the set time, etc., and the sand may not set correctly.
In order to make molds, I am going to have to turn on the heater in the shed.
The sand needs to be some reasonable temperature too.
Once the mold is made, a carboard box has to be placed over it, with a hair dryer heating the air inside the box.
If the mold is cold, it will cause a partial fill.
If I don't do a winter pour, the danger of waiting for warm weather is I will get too detached from this build and lose momentum, and chances are I will get too busy with work projects too.
Now is a good time to do some aluminum pours, so I need to do a winter setup.
I could probably put some sand in an old cooler, and put a light bulb in there.
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I made it to the hardware store, and purchased some drywall joint compound.
It comes in 5, 20, 45 and 90 minute set times.
I got the 45 minute stuff; that should be plenty of time to spray it on.
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It comes in 5, 20, 45 and 90 minute set times.
I got the 45 minute stuff; that should be plenty of time to spray it on.
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I know vinegar will slow down the set time of plaster, it may work on the drywall compound as well. Bob
I played around with the 45 minute sheetrock joint compound this morning.
It is very inexpensive material; an 18 lb bag for $12.00
This is a lifetime supply.
I mixed up perhaps 40/60 compound to water, and it was too thick to be drawn up to the spray head.
I dropped back the compound amount, and did get it to spray, but it is slightly watery, and slowly migrates a bit off the part, and puddles slightly at the bottom of the part.
If you get the sprayer too close to the surface, you get an uneven coat, but backing off a bit gives a nice even coating.
Overall, the spray coating is thin, and is doing what I want it to do, but I need a slightly thicker material.
I think it is going to take a few psi on the container to force the material up to the spray head.
I have an aquarium pump somewhere; I need to find that.
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It is very inexpensive material; an 18 lb bag for $12.00
This is a lifetime supply.
I mixed up perhaps 40/60 compound to water, and it was too thick to be drawn up to the spray head.
I dropped back the compound amount, and did get it to spray, but it is slightly watery, and slowly migrates a bit off the part, and puddles slightly at the bottom of the part.
If you get the sprayer too close to the surface, you get an uneven coat, but backing off a bit gives a nice even coating.
Overall, the spray coating is thin, and is doing what I want it to do, but I need a slightly thicker material.
I think it is going to take a few psi on the container to force the material up to the spray head.
I have an aquarium pump somewhere; I need to find that.
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I am going to try dabbing a thicker mix on with a sponge.
Edit:
A bit of a rough surface.
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Edit:
A bit of a rough surface.
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Since I have 18 lbs of the joint compound, and since I have 45 minutes to work with, I am going to try an thicker mix in the Passche slurry sprayer.
I think it can handle a lot more pressure (instructions say 75 psi max).
I don't recall if it allows canister pressurization or not, but I could add an air fitting, and put a few psi into the canister with an aquarium pump.
The tip size can be changed, but I probably only have the tip that was supplied with the sprayer.
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Another way I have seen people spray heavy slurry is with a sandblaster for coating the interior of their furnaces.
I may try that first.
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I think it can handle a lot more pressure (instructions say 75 psi max).
I don't recall if it allows canister pressurization or not, but I could add an air fitting, and put a few psi into the canister with an aquarium pump.
The tip size can be changed, but I probably only have the tip that was supplied with the sprayer.
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Another way I have seen people spray heavy slurry is with a sandblaster for coating the interior of their furnaces.
I may try that first.
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I think the Paasche sprayer, and the sandblaster sprayer are going to have to be ruled out.
They would both work with slurry, but they are too large for this application.
Plan B (or C,D,E.....whichever plan we are currently on) is to pressure feed a thicker slurry to the airbrush, with the slurry being thick enough to not run, regardless of how heavy it is sprayed on.
I mixed up some joint compound that is too heavy to be siphon drawn up into the airbrush, and put it in a ziplock, and forced it into the airbrush using a cake decoration type affair, using a ziplock bag.
The forced slurry actually worked, and it is thick enough to prevent any runs or sags.
So I just need to find my aquarium pump, and make a pressure container, perhaps 1/2 cup, that feeds into the airbrush.
I will need a fine needle valve to feed air into the container.
The good part about the airbrush is it has its own small compressor, and it is small, so good for very fine work.
The parts that I need to coat with filler are relatively small.
I think we have a solution using the airbrush.
(not my photo below, but you get the idea of how I tested the forced slurry method)
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They would both work with slurry, but they are too large for this application.
Plan B (or C,D,E.....whichever plan we are currently on) is to pressure feed a thicker slurry to the airbrush, with the slurry being thick enough to not run, regardless of how heavy it is sprayed on.
I mixed up some joint compound that is too heavy to be siphon drawn up into the airbrush, and put it in a ziplock, and forced it into the airbrush using a cake decoration type affair, using a ziplock bag.
The forced slurry actually worked, and it is thick enough to prevent any runs or sags.
So I just need to find my aquarium pump, and make a pressure container, perhaps 1/2 cup, that feeds into the airbrush.
I will need a fine needle valve to feed air into the container.
The good part about the airbrush is it has its own small compressor, and it is small, so good for very fine work.
The parts that I need to coat with filler are relatively small.
I think we have a solution using the airbrush.
(not my photo below, but you get the idea of how I tested the forced slurry method)
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Here is my setup for a pressurized slurry-spraying rig.
Time to try it out.
Edit:
This is basically the same arrangement as I use on my foundry oil burner, but in miniature.
I could do a little kerosene test, but the wife would not be happy with me playing with the mini-flame thrower in the office.
My first oil burner test was with a $20 Harbor Freight paint sprayer and some kerosene; be cautious if you do this.......BIG flames.
Edit02:
I am going to add an on-off switch to the aquarium pump, so that I can stop the slurry flow, or maybe just kink the air tubing.
The air valve is for tuning the air flow amount, and not intended for on-off.
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Time to try it out.
Edit:
This is basically the same arrangement as I use on my foundry oil burner, but in miniature.
I could do a little kerosene test, but the wife would not be happy with me playing with the mini-flame thrower in the office.
My first oil burner test was with a $20 Harbor Freight paint sprayer and some kerosene; be cautious if you do this.......BIG flames.
Edit02:
I am going to add an on-off switch to the aquarium pump, so that I can stop the slurry flow, or maybe just kink the air tubing.
The air valve is for tuning the air flow amount, and not intended for on-off.
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I started with a 1:1 ratio of water to joint compound, but that was a bit on the watery side.
I added 1 teaspoon of joint compound at a time, and ended up adding three before I got a slurry thick enough to most likely not run.
The spray is rather fine, and I am tempted to enlarge the hole in the tip, but I don't have a way to unenlarge it if I get it too big.
Spraying too close gives a coating that is a bit too thick, and on the lumpy side.
Pulling the airbrush back away from the surface gives a nice even coat.
Letting it dry now, to see how well it sands.
I am not sure what the black specs are, but they don't seem to be a problem.
I have gotten a lot of use out of the test dog print.
I was trying to spray and take the videoall at the same time, so sort of wild with the spray, but I think you get the idea.
None of the vertical surfaces are running or sagging, so that is good.
A high viscosity slurry like this would not be able to be sprayed on without a pressurized container.
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I added 1 teaspoon of joint compound at a time, and ended up adding three before I got a slurry thick enough to most likely not run.
The spray is rather fine, and I am tempted to enlarge the hole in the tip, but I don't have a way to unenlarge it if I get it too big.
Spraying too close gives a coating that is a bit too thick, and on the lumpy side.
Pulling the airbrush back away from the surface gives a nice even coat.
Letting it dry now, to see how well it sands.
I am not sure what the black specs are, but they don't seem to be a problem.
I have gotten a lot of use out of the test dog print.
I was trying to spray and take the videoall at the same time, so sort of wild with the spray, but I think you get the idea.
None of the vertical surfaces are running or sagging, so that is good.
A high viscosity slurry like this would not be able to be sprayed on without a pressurized container.
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Attachments
I force-dried the coating with a heater, and sanded it with 400 grit sandpaper.
It is doing what I want it to do.
The black spots are air bubbles, apparently, but don't seem to make a big difference.
There will be a top coat of shellac.
I will probaby use a finer sandpaper, more like 600 or 800 grit, if there is such a thing.
This is a good method, so I will start spraying the hopper parts.
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It is doing what I want it to do.
The black spots are air bubbles, apparently, but don't seem to make a big difference.
There will be a top coat of shellac.
I will probaby use a finer sandpaper, more like 600 or 800 grit, if there is such a thing.
This is a good method, so I will start spraying the hopper parts.
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I got the frame cut out and welded for the 3D printer enclosure.
I need to assemble it, wrap it in plastic wrap, and then install the fan.
The PLA fumes have gotten to the point where they bother me a great deal, and so this enclosure will have an inline fan that is vented to outside the house.
This is a quick and dirty assembly, but sufficient for what I need it for.
No awards will be won for this housing, as far as cosmetics anyway.
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I need to assemble it, wrap it in plastic wrap, and then install the fan.
The PLA fumes have gotten to the point where they bother me a great deal, and so this enclosure will have an inline fan that is vented to outside the house.
This is a quick and dirty assembly, but sufficient for what I need it for.
No awards will be won for this housing, as far as cosmetics anyway.
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@GreenTwin , seems to me that, for you, the journey is maybe more important, and that the end result is a bit anticlimactic. I totally understand.
I just blog along with what I am doing.
This is my build blog.
Often I think outloud, and then type that.
That forces me to think things through.
Some folks hate my format; I don't care; there are plenty of other builds to read.
I don't have an agenda, other than to build cast engines.
Folks can follow along, or tune it out.
I really don't adhere to anyone elses requirements or expectations in my blogs/builds.
Others can do what they want in their own builds/blogs if they feel the need to adhere to some rigid requirements.
It is interesting for me to come back later and read about what it took to get it done.
I could wait and just publish the finished engine, but that does not teach others how to do what I do.
I like to publish my engine builds.
I would like to publish this build.
I would do my own publishing, and just issue a pdf file to anyone who is interested, for free.
I would certainly take this engine to engine shows if I get it completed, since there would only be one of this size in the world.
I have admired this engine since I saw one in the early 1970's.
The ability to reverse-engineer an old engine, and then cast it at 1/2 scale in gray iron is not something I ever imagined would be possible, so this is dreamy stuff for me.
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This is my build blog.
Often I think outloud, and then type that.
That forces me to think things through.
Some folks hate my format; I don't care; there are plenty of other builds to read.
I don't have an agenda, other than to build cast engines.
Folks can follow along, or tune it out.
I really don't adhere to anyone elses requirements or expectations in my blogs/builds.
Others can do what they want in their own builds/blogs if they feel the need to adhere to some rigid requirements.
It is interesting for me to come back later and read about what it took to get it done.
I could wait and just publish the finished engine, but that does not teach others how to do what I do.
I like to publish my engine builds.
I would like to publish this build.
I would do my own publishing, and just issue a pdf file to anyone who is interested, for free.
I would certainly take this engine to engine shows if I get it completed, since there would only be one of this size in the world.
I have admired this engine since I saw one in the early 1970's.
The ability to reverse-engineer an old engine, and then cast it at 1/2 scale in gray iron is not something I ever imagined would be possible, so this is dreamy stuff for me.
.
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Brian Rupnow inspired me to learn Solidworks, but there another guy who use to post here named Rob Wilson, and he also used Solidworks to design engines.
Rob also built a foundry, made his own patterns, and cast his own engine parts.
Rob sent me information about how to use Solidworks to design model engines, and some foundry information too.
After seeing what Rob and Brian were doing, I decided to learn Solidworks, and build my own foundry.
I saved some photos that Rob posted.
He vanished one day, and I have never seen him post anything again.
Rob did some fantastic pattern and engine casting work, as shown below.
Very talented fellow.
If anyone knows where he got off to, please let us know.
(all photos by Rob Wilson)
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Rob also built a foundry, made his own patterns, and cast his own engine parts.
Rob sent me information about how to use Solidworks to design model engines, and some foundry information too.
After seeing what Rob and Brian were doing, I decided to learn Solidworks, and build my own foundry.
I saved some photos that Rob posted.
He vanished one day, and I have never seen him post anything again.
Rob did some fantastic pattern and engine casting work, as shown below.
Very talented fellow.
If anyone knows where he got off to, please let us know.
(all photos by Rob Wilson)
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