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Thread: The Bucket Foundry

  1. #3961
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    Quote Originally Posted by Michael Moore View Post
    Juha, now you need to buy 3 more printers so you can have two cylinders ready to invest every 20 hours. Or two cylinders every 40 hours if you decide you need to go to a slower/higher resolution setting.

    I suspect that if you designed a water-cooled cylinder you might be able to print them a lot faster. Fins add a lot of area/complexity to the pattern. Close-spaced and deep fins make machining a pattern a bigger job so I presume they will slow down the printing process too.

    How many meters/spools of filament does it take?

    Every now and then I go and look at the information on the Formlabs Form2 SLA printer and their resin designed for investment casting. Being able to get a pattern that is very smooth (compared to a filament printer) right off the printer is appealing, but it all gets pretty expensive and I would need to be using it a lot to be able to justify it, especially since I've already got a nice 4 axis CNC milling machine. But printing the patterns would allow some complexity that would be hard to achieve with subtractive machining, and being able to let a printer run at night would be nice compared to having to sit and babysit the mill.

    If you have filling issues with the casting you might try adding vacuum or centrifugal force to help fill the mold fully/quickly.

    Have you considered printing core boxes and maybe an inverse pattern that you could use to make a positive pattern from a sturdy epoxy (or an aluminum casting) so you could do sand casting? If you want to make a production run sand casting would let you make a lot more molds for a given time investment.

    cheers,
    Michael
    If it ever happens that I should be making dozens of these, I'd probably contact some chinese through mfg.com.
    Water-cooling would definitely be easier and faster to print but since original cylinder for Suzuki PV is air-cooled so are these. Of course some proto cylinders with water-cooling can(and eventually will ) be made.
    One mold takes ~300 grams filament wich is next to nothing in money. I just don't see any reason to make core boxes. Huge amount of work to get them to work and while fixing them I have modelled at least three better cylinders demanding new cores
    Filling issues were due to lousy riser design and maybe too cool mold added with some loose plaster. I didn't clean the mold after drying/burning it other than rotating it few times!

    Quote Originally Posted by WilDun
    JT
    Congratulations - a very good start to 2019 and being able to start off by making a finned cylinder will give you a massive head start!

    I am about to try some castings soon - the fact that there is no longer any draught (draft to others) required for pattern withdrawl will be a bonus.
    I'm not too clear on just how long it takes to burn out the PLA, - I heard someone, somewhere, suggest that when the mould reaches a dull red is adequate?....... then, what is the best way to ensure that all the ash has been removed? air blast ? vacuum? or both?

    I have acquired a very small printer (Malyan 200) - it actually works very well despite it's cantilever design and small size, but I think the best of the cheapies - very suitable for learning the skill without breaking the bank!.

    I bought a roll of PLA from Jaycar but it was totally brittle and unuseable so I took it back and they replaced it - no worries!! it probably had been left exposed to our fierce ultra violet rays here in NZ - so keep it covered Kiwis!

    I'll be looking forward to learning a lot from you guys this year!
    Plaster dryed about four hours in 200C and then came the smoke from PLA(and the bucket holding the plaster and the bowl under the mold). Next six hours there were quite a smell and mold was held in 300C. Last couple of hours the temperature was about 370C.
    PLA did not leave any ash to remove but play dough did. So did my risers which were made of XPF-insulation material(Foam of a kind)

    And what comes to 3D-printing(this is for everybody): Just do it. Printers and slicers are consumer electronics these days and you can see it by how easy they are to use. You don't need any special knowledge to get started and even cylinder mold printing will be succesful with only few tweaks if even that!

    On this week I have mostly been making expanding mandrel and some pipes...
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    Last edited by jt-87; 4th January 2019 at 20:14. Reason: link to pipe pictures

  2. #3962
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    . . . and some pipes. You don't say?
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  3. #3963
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    Quote Originally Posted by jt-87 View Post
    .............Plaster dryed about four hours in 200C and then came the smoke from PLA(and the bucket holding the plaster and the bowl under the mold). Next six hours there were quite a smell and mold was held in 300C. Last couple of hours the temperature was about 370C.
    PLA did not leave any ash to remove but play dough did. So did my risers which were made of XPF-insulation material(Foam of a kind)

    And what comes to 3D-printing(this is for everybody): Just do it. ................ You don't need any special knowledge to get started and even cylinder mold printing will be succesful with only few tweaks if even that!
    Thanks for the info ....

    I hope I can afford the gas to burn out the PLA!!

    From my limited knowledge of printers, I think that there may be a few things I need to learn regarding how to place the pattern to be printed on the platen! - quite tricky!

    I don't think that 3D printers are the"Be all, End all" here - Quite honestly I would still like to try making wooden patterns as well to find out which process is best, I do think however that each has has its own niche - and so, don't believe that one will completely take over the other - horses for courses I guess!

    - but as I often say, I know sweet F.A. - there's no secret about that!
    Freedom of speech is important but if what we say is considered incorrect by our peers, they will quickly put us right.
    P.C. will eventually destroy our right to tell the truth.

  4. #3964
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    Flet hasn't posted since 10th November?
    Anyone seen him post on arsebook or other places?



    Kinky is using a feather. Perverted is using the whole chicken

  5. #3965
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    Will, got the printer running. It &/or I seem to have problem with getting the PLA (200 & 60 deg C @ 0.3 layer) to stick on the bed for the first layer. See mess in the morning. Then I printed on a Raft and it was ok. As the Raft first layer stuck down ok on the bed, then there must be some subtle setting differences. Tried hairspray, but didn’t help with either the printing or my good looks.

    As an aside, I have been thinking about some complex/intricate cooling passages which would be too delicate to make using sand cores. So, using 3D printed coreboxes, one could make stronger plaster cores, but these obviously have to be removed. Did some simple dissolving tests immersing some small "plaster of Paris" bits in both bicarb of soda and vinegar. Vinegar was the winner. Not perfect and not instantaneous. Will try it a bit more, but also putting the sample in an ultrasonic bath.

    MM, I have to agree with you on “manufacturing technology a very interesting subject”.

    Huser, I’m pretty sure that Fletto is happily busy proving and demonstrating his engine and cylinders around Kiwiland with his gyro.

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    "Perfection is the enemy of progress"

  6. #3966
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    Quote Originally Posted by husaberg View Post
    Flet hasn't posted since 10th November? Anyone seen him post on arsebook or other places?
    Yep, on Farcebook, couple of days ago. Plus, in his newyear-email he revealed amongst other things that he is busy professionalizing his foundry and he's going to build a series of his 700cc autogiro engines.

  7. #3967
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    So, after we get a bit better at CAD & 3D printing, we could make something like this:

    https://www.facebook.com/Engineering...0790436728833/
    "Perfection is the enemy of progress"

  8. #3968
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    Quote Originally Posted by husaberg View Post
    Friends of mine managed to produce wonderful lightweight aluminium castings without any Selective Laser Melting equipment. All they did was ask my advice about casting and then choose to ignore it .
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  9. #3969
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    Extra multiple sub ports?
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  10. #3970
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    Quote Originally Posted by Frits Overmars View Post
    Yep, on Farcebook, couple of days ago. Plus, in his newyear-email he revealed amongst other things that he is busy professionalizing his foundry and he's going to build a series of his 700cc autogiro engines.
    Cool i was worried he might haver been abducted by Austrians
    Quote Originally Posted by Frits Overmars View Post
    Friends of mine managed to produce wonderful lightweight aluminium castings without any Selective Laser Melting equipment. All they did was ask my advice about casting and then choose to ignore it .
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    On the plus side it will retain oil good until it passes through to the outside.
    So no degassing was used i am guessing.
    From what i uderstand about material strength those cross sections they are getting close to replicating the best strength to weight achievable.
    Looking at the pic they are at Human level, birds are a bit more evolved.



    here are the wing feathers

    Even done to he nano structure of the bones



    Metal bubble wrap
    https://www.core77.com/posts/25212/N...tronger-Better


    Open-cell

    Open-cell metal foam

    CFD (numerical simulation) of fluid flow and heat transfer on an open cell metal foam
    Open celled metal foam, also called metal sponge,can be used in heat exchangers (compact electronics cooling, cryogen tanks, PCM heat exchangers), energy absorption, flow diffusion, and lightweight optics. The high cost of the material generally limits its use to advanced technology, aerospace, and manufacturing.
    Fine-scale open-cell foams, with cells smaller than can be seen unaided, are used as high-temperature filters in the chemical industry.
    Metallic foams are used in compact heat exchangers to increase heat transfer at the cost of reduced pressure.However, their use permits substantial reduction in physical size and fabrication costs. Most models of these materials use idealized and periodic structures or averaged macroscopic properties.

    Metal sponge has very large surface area per unit weight and catalysts are often formed into metal sponge, such as palladium black, platinum sponge, and spongy nickel. Metals such as osmium and palladium hydride are metaphorically called "metal sponges", but this term is in reference to their property of binding to hydrogen, rather than the physical structure.

    Manufacturing
    Open cell foams are manufactured by foundry or powder metallurgy. In the powder method, "space holders" are used; as their name suggests, they occupy the pore spaces and channels. In casting processes, foam is cast with an open-celled polyurethane foam skeleton.
    Closed-cell
    Closed-cell metal foam was first reported in 1926 by Meller in a French patent where foaming of light metals, either by inert gas injection or by blowing agent, was suggested.[7] Two patents on sponge-like metal were issued to Benjamin Sosnik in 1948 and 1951 who applied mercury vapor to blow liquid aluminium.[8][9]

    Closed-cell metal foams were developed in 1956 by John C. Elliott at Bjorksten Research Laboratories. Although the first prototypes were available in the 1950s, commercial production began in the 1990s by Shinko Wire company in Japan. Closed-cell metal foams are primarily used as an impact-absorbing material, similarly to the polymer foams in a bicycle helmet but for higher impact loads. Unlike many polymer foams, metal foams remain deformed after impact and can therefore only be deformed once. They are light (typically 10–25% of the density of an identical non-porous alloy; commonly those of aluminium) and stiff and are frequently proposed as a lightweight structural material. However, they have not been widely used for this purpose.

    Closed-cell foams retain the fire resistance and recycling potential of other metallic foams, but add the property of flotation in water.

    Manufacturing
    Foams are commonly made by injecting a gas or mixing a foaming agent into molten metal.[10] Melts can be foamed by creating gas bubbles in the material. Normally, bubbles in molten metal are highly buoyant in the high-density liquid and rise quickly to the surface. This rise can be slowed by increasing the viscosity of the molten metal by adding ceramic powders or alloying elements to form stabilizing particles in the melt, or by other means. Metallic melts can be foamed in one of three ways:

    by injecting gas into the liquid metal from an external source;
    by causing gas formation in the liquid by admixing gas-releasing blowing agents with the molten metal;
    by causing the precipitation of gas that was previously dissolved in the molten metal.
    To stabilize the molten metal bubbles, high temperature foaming agents (nano- or micrometer- sized solid particles) are required. The size of the pores, or cells, is usually 1 to 8 mm. When foaming or blowing agents are used, they are mixed with the powdered metal before it is melted. This is the so-called "powder route" of foaming, and it is probably the most established (from an industrial standpoint). After metal (e.g. aluminium) powders and foaming agent (e.g.TiH2) have been mixed, they are compressed into a compact, solid precursor, which can be available in the form of a billet, a sheet, or a wire. Production of precursors can be done by a combination of materials forming processes, such as powder pressing,[11] extrusion (direct[12] or conform[13]) and flat rolling.[14]
    Composites
    Composite metal foam (CMF) is formed from hollow beads of one metal within a solid matrix of another, such as steel within aluminium, show 5 to 6 times greater strength to density ratio and more than 7 times greater energy absorption than previous metal foams.[15]

    A less than one inch thick plate has enough resistance to turn a 7.62 x 63 mm standard-issue M2 armor piercing bullet to dust. The test plate outperformed a solid metal plate of similar thickness, while weighing far less. Other potential applications include nuclear waste (shielding X-rays, gamma rays and neutron radiation) transfer and thermal insulation for space vehicle atmospheric re-entry, with twice the resistance to fire and heat as the plain metals.[16]

    CMF can replace rolled steel armor with the same protection for one-third the weight. It can block fragments and the shock waves that are responsible for brain injuries. Stainless steel CMF can block blast pressure and fragmentation at 5,000 feet per second from high explosive incendiary (HEI) rounds that detonate 18 inches from the shield. Steel CMF plates (9.5 mm or 16.75 mm thick) were placed 18 inches from the strikeplate held up against the wave of blast pressure and against the copper and steel fragments created by a 23×152 mm HEI round (as in anti-aircraft weapons) as well as a 2.3mm aluminum strikeplate

    So it looks like you can do it where you want with selective laser sintering
    It also looks like maybe its the secret to the M1 Abrams armour. I think the elastic layer that encases the ceramics is Bubble metal matrix
    Chobham armour is the informal name of a composite armour developed in the 1960s at the British tank research centre on Chobham Common, Surrey. The name has since become the common generic term for composite ceramic vehicle armour. Other names informally given to Chobham Armour include "Burlington" and "Dorchester." "Special armour" is a broader informal term referring to any armour arrangement comprising "sandwich" reactive plates, including Chobham Armour.

    Although the construction details of the Chobham armour remain a secret, it has been described as being composed of ceramic tiles encased within a metal framework and bonded to a backing plate and several elastic layers. Due to the extreme hardness of the ceramics used, they offer superior resistance against shaped charges such as high explosive anti-tank (HEAT) rounds and they shatter kinetic energy penetrators.

    The armour was first tested in the context of the development of a British prototype vehicle, the FV4211, and first applied on the preseries of the American M1. Only the M1 Abrams, Challenger 1, and Challenger 2 tanks have been disclosed as being thus armoured. The framework holding the ceramics is usually produced in large blocks, giving these tanks, and especially their turrets, a distinctive angled appearance.



    Kinky is using a feather. Perverted is using the whole chicken

  11. #3971
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    Shell sand core molding machine, first plattern of three. Machines to make Machines. Before and after.
    I call it a sand roll over machine, hence the piviot bearing.
    Plattern is 60mm thick, 480 x 580 size.
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  12. #3972
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    The main reason Im getting into this is I'm sick of tripping over these large lumps of steel on the floor.
    This machine will mass produce sand cores at about a minute or two cycle time. Also can do outside sections of molds. Cores are strong, permeable, accurite, extremely long shelf life and super quick to make.
    Dies must be metal.

  13. #3973
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    Quote Originally Posted by ken seeber View Post
    Will, got the printer running. It &/or I seem to have problem with getting the PLA (200 & 60 deg C @ 0.3 layer) to stick on the bed for the first layer. See mess in the morning. Then I printed on a Raft and it was ok. As the Raft first layer stuck down ok on the bed, then there must be some subtle setting differences. Tried hairspray, but didn’t help with either the printing or my good looks.
    Ken
    I'm using 210 and around 55-60 (for PLA) - good with either 'raft' or 'Brim', (using painter's masking tape with hairspray. - first making sure it's properly up to temp before starting print. - works on mine but just a suggestion for yours. - nice looking machine.
    I'm also trying 'Design Spark Mechanical' - it does everything on .STL files and it seems that Cura converts them to CNC, probably I need to reset Cura, - not great as yet!

    Was looking into how difficult it might be to print cylinder fins and as far as I can see it would be better not to try, (time taken and difficult to support easily), instead just to cut the fins from sheet PLA (if you can obtain that) and glue them to a nicely printed cylinder (the insides of the passages being smoothed of course) or is that always even necessary? - guess you could get away with that if it's not too coarse (there are lots of theories on boundary layers and rough surfaces etc!).

    Neil Good to see you getting serious - I have always been great believer in the shell moulding process - stinks but good!
    Last edited by WilDun; 6th January 2019 at 12:30. Reason: additional question
    Freedom of speech is important but if what we say is considered incorrect by our peers, they will quickly put us right.
    P.C. will eventually destroy our right to tell the truth.

  14. #3974
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    Tried 215deg and 55deg but I've finally settled for 210/60 which seems to work best - love my little cheap printer! -
    getting there and quickly learning Fusion 360 (in my own way)
    Fusion (as I see it ) is very very good but will ultimately become expensive (nothing is free)! - still looking for alternitaves - anybody? - The big problem at the moment is the .stl files produced by DesignSpark Mechanical being translated into CNC!

    Still needs to be proven to me that "lost PLA" is superior to the traditional methods of casting metal (as practiced by Flettner)!

    I am enjoying learning 3D draughting (drafting to you USA guys) and it keeps my old mind ticking over!- new lease of life! - very happy!
    Freedom of speech is important but if what we say is considered incorrect by our peers, they will quickly put us right.
    P.C. will eventually destroy our right to tell the truth.

  15. #3975
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    I had a brief but interesting email exchange with the owner of a motorsports aftermarket manufacturing firm who bought a Stratasys Objet 30 printer (US$25-30K). He said he uses that only to print master patterns. Here's an excerpt from our conversation.

    The actual production patterns were cast (integral with the match plates) from aluminum, from urethane copies of those masters poured into silicone impressions, in the usual way metal patterns are made.

    The acrylic output of the Objet 30 would hold never hold up as working patterns, but it does print <30-micron layers and leaves a slick enough finish that handwork is mostly eliminated. So the work it avoids is mostly a lot of milling and sanding.

    In this case, printing the patterns avoided a ton of machining as well, and no postprocessing-just convert to an STL file and go, no tool definitions, no toolpath generation trial and error, etc. We originally machined all our coreboxes from aluminum blocks, but now we just print those too and let the foundry use them as patterns. They can do that cheaper than we can mill them, especially when you consider ribbing the back side and trying for a uniform thickness.
    https://www.3dsystems.com/on-demand-...sting-patterns

    Like 3DSystems FormLabs have an investment casting resin for their Form SLA printers -- $300/liter.

    So he's using 3D patterns but not lost as "lost" PLA/wax. If you need to make a lot of lost wax parts you might be better off using a good printer to make the master pattern and mold it to then make the production waxes vs doing a lot of printed "waxes". Of course, an SLA printed "wax" might allow you to have features that would be difficult to pull from a rubber mold if using traditional injected wax so YMMV and "horses for courses" apply.

    cheers,
    Michael

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