@GreenTwin That bottle engine would be a bear to mold. The cores would be real head scratchers. Nice engine tho, and definitely worth the extra effort.
Thanks for sharing.
Todd.
Thanks for sharing.
Todd.
Casting Kits I would like to see For Sale Again
- Thread starter GreenTwin
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Yeah, the undercuts on the crosshead guides had me thinking for a bit. If they were solid instead of hollowed, I wonder if you'd get sinkers on the external surface. It's not like undercuts on an injection mold though, if the cores are discarded after casting, correct?
It would also be interesting to create line boring tooling for it to flycut the curvature (on sliding surface). At least in my case I wouldn't be able to extend a boring head that far for a diameter that would allow it to enter from above. Makes for an interesting puzzle.
Boring on the lathe would be easy enough with a fixed steady adding support for the top collar. Alternative would be to use an angle plate or two to mount the casting on the lathe cross slide and do the cutting with a between ctrs boring bar.
As to moulding and my thinking if I make one from solid then the flange at the bottom would be separate and the bottle stop at the narrowest point. The flange would have the bearing supports cast/machined in and be inserted into the bottom of the bottle. As for the cross head guides it depends which engine you choose to replicate or if it will just be a generic bottle engine in which case the guides can be flat faced or not have the undercut.
The core for the cross head guides would be quite simple but you would have to split the core down the middle, curved face would be cast flat or with draft so the core could be removed from the corebox. Or if fabricating easy enough to add the guides to the main bottle by various means and finish machine when in position.
As to moulding and my thinking if I make one from solid then the flange at the bottom would be separate and the bottle stop at the narrowest point. The flange would have the bearing supports cast/machined in and be inserted into the bottom of the bottle. As for the cross head guides it depends which engine you choose to replicate or if it will just be a generic bottle engine in which case the guides can be flat faced or not have the undercut.
The core for the cross head guides would be quite simple but you would have to split the core down the middle, curved face would be cast flat or with draft so the core could be removed from the corebox. Or if fabricating easy enough to add the guides to the main bottle by various means and finish machine when in position.
I would have to cast it like they did in the day, because why do it any different?
I really consider my build(s) as just reduced sized engines, and not models.
I could see simplifying perhaps a model Merlin engine, but beyond that, I don't see any reason to change from an original design.
I have the molding figured out for the bottle engine; I just have to recall what I figured out, LOL, old age is heck.
The most intricate molding and core engine I am aware of is the Speedy Twin, and luckily I have had access to the original patterns and frame core box.
I also found one of the original passage coreboxes, and that is a work of art.
The Speedy Twin has an array of cores above the cylinders, to allow the engine to be reversed without using a link, and with only two eccentrics (one per cylinder).
The Soule plant was the "Master of Cores" in my opinion.
There are a lot of chaplets in the top of a Speedy Twin, and if you are familiar with the cores above the cylinders, you understand why.
One huge advantage we as modelers have is that someone has already come up with these old designs, and they have already figured out how to cast them, so we don't have to create our own unique engine designs.
We only have to reverse engineer how they molded these old engines; ie: where are the cores, parting lines, coreprints, etc.
I can figure out the runners and gating on any engine; I have studied that topic a LOT.
If you study old engines, you discover that the draft angle is added to allow the pattern to be retracted from the sand mold, without breaking the mold.
This means that there is one direction in which a pattern (generally a patter half) can be pulled from the sand, and this allows one to find the parting line, which is usually between the cope (the upper mold half) and the drag (the lower mold half).
For the bottle engine, the cylinder and frame parting lines are like this:
I really consider my build(s) as just reduced sized engines, and not models.
I could see simplifying perhaps a model Merlin engine, but beyond that, I don't see any reason to change from an original design.
I have the molding figured out for the bottle engine; I just have to recall what I figured out, LOL, old age is heck.
The most intricate molding and core engine I am aware of is the Speedy Twin, and luckily I have had access to the original patterns and frame core box.
I also found one of the original passage coreboxes, and that is a work of art.
The Speedy Twin has an array of cores above the cylinders, to allow the engine to be reversed without using a link, and with only two eccentrics (one per cylinder).
The Soule plant was the "Master of Cores" in my opinion.
There are a lot of chaplets in the top of a Speedy Twin, and if you are familiar with the cores above the cylinders, you understand why.
One huge advantage we as modelers have is that someone has already come up with these old designs, and they have already figured out how to cast them, so we don't have to create our own unique engine designs.
We only have to reverse engineer how they molded these old engines; ie: where are the cores, parting lines, coreprints, etc.
I can figure out the runners and gating on any engine; I have studied that topic a LOT.
If you study old engines, you discover that the draft angle is added to allow the pattern to be retracted from the sand mold, without breaking the mold.
This means that there is one direction in which a pattern (generally a patter half) can be pulled from the sand, and this allows one to find the parting line, which is usually between the cope (the upper mold half) and the drag (the lower mold half).
For the bottle engine, the cylinder and frame parting lines are like this:
Here are the tricky parts, especially the crosshead guide.
As you can see, everything except the crosshead guide can be pulled perpendicular to the parting line.
As you can see, everything except the crosshead guide can be pulled perpendicular to the parting line.
The frame will be 3D printed (I started this in sections, see attached), to make two pattern halves.
The crosshead guide pieces will have to be loose, retract-style pieces.
The bosses on the base would also need to be retract pieces.
The corebox for the frame is the frame pattern itself.
You ram the assembled frame halves with core sand, including some core print material at the top and bottom, and then remove the two frame pattern halves.
One part of the crosshead guide is pulled with the frame pattern half.
The part of the crosshead guide with the curved surface remains in the core, and is removed by pulling sideways after the cores are split (this must be split core).
Its pretty simple really, compared to a Speedy Twin.
.
The crosshead guide pieces will have to be loose, retract-style pieces.
The bosses on the base would also need to be retract pieces.
The corebox for the frame is the frame pattern itself.
You ram the assembled frame halves with core sand, including some core print material at the top and bottom, and then remove the two frame pattern halves.
One part of the crosshead guide is pulled with the frame pattern half.
The part of the crosshead guide with the curved surface remains in the core, and is removed by pulling sideways after the cores are split (this must be split core).
Its pretty simple really, compared to a Speedy Twin.
.
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The cope and drag mold halves can be made by placing each pattern half around its core half, and then ramming the cope and drag respectively.
You would have to pay attention to the bosses at the bottom of the frame at this step, using retracts.
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You would have to pay attention to the bosses at the bottom of the frame at this step, using retracts.
.
This is where there is a big difference between what an individual working at home may do where time does not cost anything compared with the likes of what Todd is doing and as the subject of the thread is casting KITS not home casting there are factors to consider.
Complex cores take time to design & produce the boxes for, 3D printed boxes may well not last long enough for Todd's run of 50 so may need making in something more durable. All this inversted time needs to be recovered in the sale price of the kit
Then there is time and materials to make the actual core and time to place into the mould all these will add to the sale price of a casting kit as the foundry are not going to do that for nothing
Add to that there is more risk of a failed casting if a core moves or gets damaged so the foundry will want to cover needing to make say 55 sets of cores, place 55 sets of cores into the mould and take up casting time pouring the iron. This would be ontop of some trial castings to make sure what is on the screen actually works with sand and metal. Forget the fact that you (Pat) says you get perfect castings, maybe you have been lucky with the small number of iron ones you have actually done but if foundries that are casting all year round and over many years get a percentage of failures then they nee dto cover that in their overhead. Just look at some peoples complaints about Stuart castings which they honour and send out replacements for if complex cores up the failure rate then any business will want to cover themselves for the costs both actual and bad press.
I've been lucky enough to get some old castings from long out of production Alyn Foundry engines a good few of those castings were "rejects" that were hanging around that could not be sold to customers but the owner could have got away with machining when he took on comissions so in the real world not every pour comes out right.
Another reason, on several of the scratch built engines that I have done scaling from model kit drawings I have found a number of details that differ from the original a lot of those are to simplify the casting process
Take the commercial cast base for this engine easy pull out of the sand as all the edges have draft, so one pattern and no cores.
Take what it is actually like on the real engine or in this case my svratch built one with the overhanging lip, there ar emore on teh other side. You could not pull a pattern like this out of the sand you would need loose pieces etc
Another reason to deviate from the original is the practicallities of scale. A part may become quite thin when working at all but the very largest of scales so the chances of getting iron to flow into a mould that may scale to say 2mm tick would be more likely to fail or chill than one that was made over thickness to the original. I've done it myself on patterns I have made when working with people that have sold over a 1000casting kits, they suggested what to make thicker as they had the experience to know what works in practice rather than on the screen and 3D printer
Complex cores take time to design & produce the boxes for, 3D printed boxes may well not last long enough for Todd's run of 50 so may need making in something more durable. All this inversted time needs to be recovered in the sale price of the kit
Then there is time and materials to make the actual core and time to place into the mould all these will add to the sale price of a casting kit as the foundry are not going to do that for nothing
Add to that there is more risk of a failed casting if a core moves or gets damaged so the foundry will want to cover needing to make say 55 sets of cores, place 55 sets of cores into the mould and take up casting time pouring the iron. This would be ontop of some trial castings to make sure what is on the screen actually works with sand and metal. Forget the fact that you (Pat) says you get perfect castings, maybe you have been lucky with the small number of iron ones you have actually done but if foundries that are casting all year round and over many years get a percentage of failures then they nee dto cover that in their overhead. Just look at some peoples complaints about Stuart castings which they honour and send out replacements for if complex cores up the failure rate then any business will want to cover themselves for the costs both actual and bad press.
I've been lucky enough to get some old castings from long out of production Alyn Foundry engines a good few of those castings were "rejects" that were hanging around that could not be sold to customers but the owner could have got away with machining when he took on comissions so in the real world not every pour comes out right.
Another reason, on several of the scratch built engines that I have done scaling from model kit drawings I have found a number of details that differ from the original a lot of those are to simplify the casting process
Take the commercial cast base for this engine easy pull out of the sand as all the edges have draft, so one pattern and no cores.
Take what it is actually like on the real engine or in this case my svratch built one with the overhanging lip, there ar emore on teh other side. You could not pull a pattern like this out of the sand you would need loose pieces etc
Another reason to deviate from the original is the practicallities of scale. A part may become quite thin when working at all but the very largest of scales so the chances of getting iron to flow into a mould that may scale to say 2mm tick would be more likely to fail or chill than one that was made over thickness to the original. I've done it myself on patterns I have made when working with people that have sold over a 1000casting kits, they suggested what to make thicker as they had the experience to know what works in practice rather than on the screen and 3D printer
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Jason-
That is a really nice engine, but then all of your engine builds are exceptional.
Its hard to pick a "Best of JasonB" engine, but that rocking valve engine is certainly the cat's meow, and I see a casting kit in that engine.
I have seen garage/hobby folks mass produce aluminum castings, and it can be done, as seen by olfoundryman's videos.
This work is with aluminum.
One would not necessarily need to build his complex dies and such to produce limited casting runs in aluminum.
Cast iron is a little more challenging, basically from having to handle the radiant heat.
The problem with backyard casting, where someone was mass producing perhaps 100 pieces at a time of each part, is not a practical problem, and has little to do with making cores and such, but a regulatory one, where the regulations and paperwork would most likely be impossible for a small oepration to deal with.
Cores are quick and easy to make.
I have made multi-core boxes, where you can make six cores at a time, and produce six cores every 10 minutes or so, or even less with gassed sodium silicate cores. With gassed cores, you can make six cores every minute.
PM makes a lot of their own castings in house, and they make them just like I do, or so their representative told me.
I think it is safe to say that there will never be a lot of money in making castings, just because there are a limited number of folks who have the tooling and knowledge to machine and assemble castings.
I admire anyone who even tries to operate a casting kit company.
If I could purchase some of the more rare kits today, I would definitely do that, but these days one almost always sees the dreaded "out of stock" label on almost all of the old casting kits.
.
That is a really nice engine, but then all of your engine builds are exceptional.
Its hard to pick a "Best of JasonB" engine, but that rocking valve engine is certainly the cat's meow, and I see a casting kit in that engine.
I have seen garage/hobby folks mass produce aluminum castings, and it can be done, as seen by olfoundryman's videos.
This work is with aluminum.
One would not necessarily need to build his complex dies and such to produce limited casting runs in aluminum.
Cast iron is a little more challenging, basically from having to handle the radiant heat.
The problem with backyard casting, where someone was mass producing perhaps 100 pieces at a time of each part, is not a practical problem, and has little to do with making cores and such, but a regulatory one, where the regulations and paperwork would most likely be impossible for a small oepration to deal with.
Cores are quick and easy to make.
I have made multi-core boxes, where you can make six cores at a time, and produce six cores every 10 minutes or so, or even less with gassed sodium silicate cores. With gassed cores, you can make six cores every minute.
PM makes a lot of their own castings in house, and they make them just like I do, or so their representative told me.
I think it is safe to say that there will never be a lot of money in making castings, just because there are a limited number of folks who have the tooling and knowledge to machine and assemble castings.
I admire anyone who even tries to operate a casting kit company.
If I could purchase some of the more rare kits today, I would definitely do that, but these days one almost always sees the dreaded "out of stock" label on almost all of the old casting kits.
.
Thanks Pat and an perfect example of what I was saying. The time and materials that went into making those dies so that batches could be cast would not be small. Looks like he casts a lot of those so the percentage of the cost per casting would be quite small Todd would have to spread any costs over the 30-50 engines he intends to have cast. The home caster just making a one off for themselves does not have to recover their costs or earn a living from the time spent making dies, cores etc so it is upto them how much effort and complexity they put into the patterns and cores.
Why would anyone want to pay for a casting kit of that Filer and Stow engine I've consistantly found that I can fabricate engines for half the cost or less than the set of castings would cost. There is nothing in that engine that can't be done with basic manual machining though with some other subjects a few basic castings can be an advantage. back in the day when many hobby engineers just had a lathe and all the milling had to be done on that then there was a bit more need for castings but less so these days with what is available in the way of tooling and methods of construction
That brings up one of my gripes which is kits containing castings for casting sake. Why include a cast disc for say a piston or cylinder cover that costs considerably more that a slice off a length of continuously cast iron bar would cost the builder to buy themselves or even include a slice of bar in teh kit rather than a casting.
Why would anyone want to pay for a casting kit of that Filer and Stow engine I've consistantly found that I can fabricate engines for half the cost or less than the set of castings would cost. There is nothing in that engine that can't be done with basic manual machining though with some other subjects a few basic castings can be an advantage. back in the day when many hobby engineers just had a lathe and all the milling had to be done on that then there was a bit more need for castings but less so these days with what is available in the way of tooling and methods of construction
That brings up one of my gripes which is kits containing castings for casting sake. Why include a cast disc for say a piston or cylinder cover that costs considerably more that a slice off a length of continuously cast iron bar would cost the builder to buy themselves or even include a slice of bar in teh kit rather than a casting.
There is definitely an allure to casting kits, and sometimes the allure is more important than the actually usefulness of the parts.
Kits can get you close on many parts that would be otherwise difficult to replicate, such as engine blocks, cylinders, water hoppers, and flywheels, and so much of the work is already done.
More importantly, kits give you complete design drawings, and machining and assembly instrutions.
Without good drawings and instructions, many would fail at building an engine from castings or bar stock.
I have to agree that there is little use in some of the material in the kit, such as a short piece of bar stock for a piston.
However, some model builders don't have access to any metal at all, and so a kit serves the purpose of providing everything that is needed as far as stock material of all shapes and types, with generally the correct type of metal for the application.
I recall turning a large round block of metal that I inheirited from my dad, and I found out that it was made of the alloy "nomachinium" (pun intended) and even carbide tooling would not easily cut it.
Just because you find scrap metal does not mean it will work for an engine.
I have purchased kits, and I like casting kits, especially in gray iron.
Maury's Ball Hopper Monitor gray iron casting kit was superb, as were the drawings and instructions.
The only beef I had was I would have preferred a larger kit.
The Myers Cretors replica No.06 was a fun kit that I purchased.
Some other gray iron castings I have purchased have been extremely bad (I am not going to name names), full of hard spots and blow holes.
Casting metal is definitely an art.
Many/most that make their own castings really don't have the techniques down very well, and it does not take much error to cause a lot of casting problems.
Will we see a resurgence in model engine casting kit companies?
I would guess the chances of seeing many of those is slim.
Lets hope littlelocos and others develop some great products in the model engine casting world.
Fingers crossed.
.
Kits can get you close on many parts that would be otherwise difficult to replicate, such as engine blocks, cylinders, water hoppers, and flywheels, and so much of the work is already done.
More importantly, kits give you complete design drawings, and machining and assembly instrutions.
Without good drawings and instructions, many would fail at building an engine from castings or bar stock.
I have to agree that there is little use in some of the material in the kit, such as a short piece of bar stock for a piston.
However, some model builders don't have access to any metal at all, and so a kit serves the purpose of providing everything that is needed as far as stock material of all shapes and types, with generally the correct type of metal for the application.
I recall turning a large round block of metal that I inheirited from my dad, and I found out that it was made of the alloy "nomachinium" (pun intended) and even carbide tooling would not easily cut it.
Just because you find scrap metal does not mean it will work for an engine.
I have purchased kits, and I like casting kits, especially in gray iron.
Maury's Ball Hopper Monitor gray iron casting kit was superb, as were the drawings and instructions.
The only beef I had was I would have preferred a larger kit.
The Myers Cretors replica No.06 was a fun kit that I purchased.
Some other gray iron castings I have purchased have been extremely bad (I am not going to name names), full of hard spots and blow holes.
Casting metal is definitely an art.
Many/most that make their own castings really don't have the techniques down very well, and it does not take much error to cause a lot of casting problems.
Will we see a resurgence in model engine casting kit companies?
I would guess the chances of seeing many of those is slim.
Lets hope littlelocos and others develop some great products in the model engine casting world.
Fingers crossed.
.
Castings are the primary reason I enjoy the kits so much. I like that there's no single datum reference to start fixturing with. The grain, casting flaws, and the flash along parting lines give it a nice feel. The second part I enjoy is thinking through the dimensions and leveraging them as errors are made and the build progresses.
If I were to make the cores for the bottle engine, I wouldn't really be considering production, other than making several to make up for the failed attempts I'd likely encounter.
It is tempting to CNC everything into mass production (which also requires great skill for profitability), but I would hope castings might make a return where designers are compensated more generously for their work.
If I were to make the cores for the bottle engine, I wouldn't really be considering production, other than making several to make up for the failed attempts I'd likely encounter.
It is tempting to CNC everything into mass production (which also requires great skill for profitability), but I would hope castings might make a return where designers are compensated more generously for their work.
When you see what the far east are producing in the way of running engines for probably less than a set of just castings would cost here I can see it going the way of CNC. Just pull the "casting" out of the CNC machine at a stage before holes have been bored and tapped etc and you have a "casting" with none of the potential flaws of a real casting for those who want a kit to machine.
Stuarts are already supplying some parts like this where they can no longer get or it is cost effective to have the parts made by the old hot pressing method and I can see that increasing.
Stuarts are already supplying some parts like this where they can no longer get or it is cost effective to have the parts made by the old hot pressing method and I can see that increasing.
I know of some folks who would purchase a pre-machine, ready-to-run engine, but they are not mechanical/technical type people.
Nothing wrong with the ready made engines per se.
Those ready made engines make good shelf decoration, but rob you of the joy of learning how to design, machine, and assemble an engine.
I value the technical knowledge as much or more than the engine itself.
If you know how to do things, it opens a lot of doors.
I run a successful business because I know how to do things, or I can figure how how to do things even if I don't initially know how to do it.
It is shocking to me how many folks don't have any technical knowledge at all in this country, even many/most degreed engineers.
I feel like technical knowledge is the very foundation of a country.
Not to get all soapbox preachy, but that is my 2 cents.
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Nothing wrong with the ready made engines per se.
Those ready made engines make good shelf decoration, but rob you of the joy of learning how to design, machine, and assemble an engine.
I value the technical knowledge as much or more than the engine itself.
If you know how to do things, it opens a lot of doors.
I run a successful business because I know how to do things, or I can figure how how to do things even if I don't initially know how to do it.
It is shocking to me how many folks don't have any technical knowledge at all in this country, even many/most degreed engineers.
I feel like technical knowledge is the very foundation of a country.
Not to get all soapbox preachy, but that is my 2 cents.
.
Pat I was suggesting they supply the part machined "casting" eg all the surfaces that would have been supplied cast would be CNC cut leaving teh builder to do as much machining as they would with any other casting. The design part doe snot come into any traditional casting kit as the supplier has done all of that so the builder would not have to design either way.
Thake the Stuart 10 series conrod as an example, this used to be a hot pressed item but could as easily be a casting
This is the part they now supply, CNC cut but only to the "cast" shape, the builder still has to do just a much work to that as they did the stamping except cleaning up the joint line.
So you are not going to rob anyone of learning how to machine or assemble an engine,
Yes there are those who want a ready to run and Stuarts have also always offered that option a swell as bolt together pre machined
Thake the Stuart 10 series conrod as an example, this used to be a hot pressed item but could as easily be a casting
This is the part they now supply, CNC cut but only to the "cast" shape, the builder still has to do just a much work to that as they did the stamping except cleaning up the joint line.
So you are not going to rob anyone of learning how to machine or assemble an engine,
Yes there are those who want a ready to run and Stuarts have also always offered that option a swell as bolt together pre machined
The CNC version of a cast part is new to me.
That is a clever way to make a casting for sure, if you have a CNC machine, although it would get excessively wasteful for larger parts.
CNC does seem to be the wave of the future, or the wave of the present.
I went to a technical college one time to pick up a piece of equipment, and one of the shop rooms was full of IC model engines, perhaps 30 of them (one per student), all bolted to the benches, and all running.
But there was not a machine tool (lathe, mill, etc.) in sight.
There were about six CNC machines against the wall though.
I don't think they even teach manual machining anymore, which is sort of scary to me.
Now it is as much about programming as it is about machining.
And as you know, there can be a stigma with using a CNC machine for hobby work, and thus the phrase "he has gone CNC", LOL.
I tend to look at the final product, and my preference is to produce a part/engine that is an exact scaled version of the full sized engine.
How you get those parts, and with what machines and/or programs is a matter of personal choice, and I don't get hung up on manual vs CNC, etc.
I do value the surface finish engine castings, which adds a distinct look to an engine, which I like.
And I like the convex surfaces on castings, as opposed to flat surfaces with no draft angle.
The convex surfaces gives a visually correct look to a part or engine, sort of like the slight upward arch of the horizontal lines on a Greek temple.
Convex surfaces look pretty much flat to the eye, and flat surfaces look concave to the eye.
There are terms for how the eye distorts images, but I don't recall them.
It is a subtle but very real effect.
.
That is a clever way to make a casting for sure, if you have a CNC machine, although it would get excessively wasteful for larger parts.
CNC does seem to be the wave of the future, or the wave of the present.
I went to a technical college one time to pick up a piece of equipment, and one of the shop rooms was full of IC model engines, perhaps 30 of them (one per student), all bolted to the benches, and all running.
But there was not a machine tool (lathe, mill, etc.) in sight.
There were about six CNC machines against the wall though.
I don't think they even teach manual machining anymore, which is sort of scary to me.
Now it is as much about programming as it is about machining.
And as you know, there can be a stigma with using a CNC machine for hobby work, and thus the phrase "he has gone CNC", LOL.
I tend to look at the final product, and my preference is to produce a part/engine that is an exact scaled version of the full sized engine.
How you get those parts, and with what machines and/or programs is a matter of personal choice, and I don't get hung up on manual vs CNC, etc.
I do value the surface finish engine castings, which adds a distinct look to an engine, which I like.
And I like the convex surfaces on castings, as opposed to flat surfaces with no draft angle.
The convex surfaces gives a visually correct look to a part or engine, sort of like the slight upward arch of the horizontal lines on a Greek temple.
Convex surfaces look pretty much flat to the eye, and flat surfaces look concave to the eye.
There are terms for how the eye distorts images, but I don't recall them.
It is a subtle but very real effect.
.
I put draft onto all my machined and fabricated parts that are meant to look like castings both with the manual mill/lathe or the CNC just depends what one suits the job best so CNC or fabrication does not rule out that "look"
I'll also add internal fillets and round external corners . Likewise concave, convex and compound curves can all be done with the cnc and once it is painted hard to know what is under the colour.
It's down to the builder you can have a barstock engine that looks like it was made from barstock or you can have one that looks like it was made from castings. As an idea of how long I've been doing that take a look at this engine built in 2007 and the one that I used the mechanical design aspect from on the Florida site Gallery, I do a better job of it now though.
http://www.floridaame.org/GalleryPages/g1h0252.htm
Another quick example that castings are not all what some people make them out to be. On the right the very crude but easy to make pattern and easy to cast item from the kit and on the left the fabricated one that replicates all the features of the engine it is based on.
I'll also add internal fillets and round external corners . Likewise concave, convex and compound curves can all be done with the cnc and once it is painted hard to know what is under the colour.
It's down to the builder you can have a barstock engine that looks like it was made from barstock or you can have one that looks like it was made from castings. As an idea of how long I've been doing that take a look at this engine built in 2007 and the one that I used the mechanical design aspect from on the Florida site Gallery, I do a better job of it now though.
http://www.floridaame.org/GalleryPages/g1h0252.htm
Another quick example that castings are not all what some people make them out to be. On the right the very crude but easy to make pattern and easy to cast item from the kit and on the left the fabricated one that replicates all the features of the engine it is based on.
@Jasonb This is spot on. Our core boxes are sand-cast aluminum, machined and polished smooth. These are set up for a hot-process, shell core (blown) coremaking machine at the foundry we work with in Hanover, PA -- another reason to work closely with your foundryman. The patterns for the core boxes are 3D printed, epoxy-coated, and then loose cast in green sand or no-bake sand molds. They are good for thousands of iterations. These can also be hand filled and gassed or baked if needed. The matchplates are baltic birch ply with 3D printed or resin-cast patterns complete with all gates and risers. They are coated in an epoxy resin and/or an industrial lacquer. These may last for 500 or more molds before requiring any major service. This takes a lot of my time, but saves tremendously at the foundry. Nearly all older model engine kits are not made with production patterns.
Since Littlelocos is not my "day job", I don't charge for my time for researching, designing, patternmaking, trips to the foundry, dressing out castings, cutting stock, machining gears, etc. etc. If I did, I wouldn't be able to sell anything as the price would be crazy. When we go to shows, we hope to recoup the costs of what we sell, plus the booth, hotel, food, and gas. (This doesn't usually happen.) We usually start getting ready for the Cabin Fever show in November and go full time between Christmas and New Year and the week before the show. That said, at 55yo I'm still looking forward to retiring before I'm 60 and going full time with the business. That will help in that we should be able to bring out 2 or 3 new kits per year afterward, and might make a few dollars in the process.
Either way, I'm having fun doing what I enjoy doing.Enjoy,
Todd.
Hopefully we can meet ways at the Black Hills Model Engineering Show if you still plan to attend. Doesn't sound like it would be a cheap roadtrip for you either. I need to sell a few things to even make it, but it would be great to pick up one of your horizontal Parsel & Weed kits. They sound great for the size.
I think a lot of this is to do with how these original models came about. I suspect many were just done by an individual who had access to a full size engine and made up the patterns, had them cast locally and then just built a one off for their own enjoyment. Then people started to see these engines and ask if castings were available so they started to run off a few more and did drawings as best they could.
Once old age caught up, health issues take over or they lost the use of a local foundry things started to go down hill or they just stopped production. These were certainly two factors that stopped Alyn foundry production plus having several aluminium master plates stolen from the foundry that ironically probably got melted down for scrap value
So then the wood patterns sit around in a barn, garage or workshop slowly deteriorating until the next of kin sell them of when disposing of the estate, that is assuming they know what they are and don't just get burnt. I've been able to borrow patterns that have sat for 25years in a damp workshop and managed to get a couple of sets cast for a small group of friends but they were not in good condition, foundry had trouble with them and the castings although just about usable would not be ones that any self respecting kit supplier would should be selling. Mostly sand sticking to the rough surfaces and getting pulled away as they were withdrawn from the mould
I also know that Doug at Mini-steam was going to have to invest in reworking patterns for several of the engines he bought up including the Galloways and what I saw of some of the others he was selling they also needed a lot of time putting into them to get them upto todays standards. He did get as far as new drawings for some. Other engines he bought up never even got cast he just had the small amount of inventory bought up at the same time as the patterns for sale on his website, that is how I got the VJ Monitor castings they were made up from remaining old castings that he had enough of to put together a set
Similar with Nick Rowland, I sent me a couple of images of damage to one of his intricate main patterns for a TypeD where the foundry had damaged it probably by mechanically compacting an air set sand rather than someone taking care hand ramming it. Finding a suitable foundry is an ongoing problem for him.
Last year I made a replacement loose piece for a set of patterns that had got lost either at the foundry or in transit Something else to be taken into consideration is maintaining patterns
So all of these are costs that anyone in the business would need to cover and therefore pass onto the customer. I wonder what the sale price of your New Holland would be if you had to factor in all the time and materials that go into it at a realistic wage? I would think it would put a lot of people off as the cost would be considerably higher.
3D Printing or CNC cutting of patterns and core boxes certainly reduces the time over wood patterns but you need more time to do the CAD drawings first rather than sketching out on a bit of wood, cost of printer and materials or cost of CNC machine, cutters etc. more so if you have to outsource printing or CNC work. Something the hobby guy doing one offs in his backyard won't figure into it but unless you are selling kits for charity should be born in mind by anyone wanting to get into the casting business where there is limited demand and often limited funds.
