[peteeng]

Hi All - Cast the billet today. Started a bit odd but evened out thru the fill. Peter Went to workshop to check on the cast and it had melted the EPS I put on top of it so it got to +80deg C which is its transition temp. Technically it doesnl;t melt at that temp just goes soft.

[peteeng]

Hi All - I released the plate all good. I then realised I should have left it in the frame for blocking,. I could have used the frame to clamp to. Now I have to figure out how to hold it to block it. Peter

[clmenz]

Hi All - Cast the billet today. Started a bit odd but evened out thru the fill. Peter Went to workshop to check on the cast and it had melted the EPS I put on top of it so it got to +80deg C which is its transition temp. Technically it doesnl;t melt at that temp just goes soft.

Peter, reading your initial description of the billet "recipe", initially seemed you were setting up a typical sandwich construction section of outside laminated skins (high performance material)-in this case carbon fiber cloth and some form of lower density material in the middle seperating the 2 skins..ie "steel fibers (dry matrixed +eventual epoxy infusion ) inbetween faces > binding the whole billet together with the epoxy infusion of steel fibers + CF faces. I guess my duh alternative explanation is the whole billet is a dry mix of chopped C.F. + varying steel fibers all infused/bonded with epoxy forming an isotropic 22mm to 25mm plate . The images that followed suggested the "duh alternative" since I didn't see any typical black carbon fiber cloth faces. In the Milli thread l, I thought you also recently decided just using 2 sheets of steel preformed and then bonded together with epoxy forming a steel laminate for the saddle was the cost effective stiffer way to go. Is the overall current process considered proprietary ? Does this billet have one of your great stress/deflection/FEA analysis plots and any mechanical properties (? bending kpsi, tortion kpsi, Youngs mod, CTE (close to steel @ about 7 vs lower in 1-4 range) , etc How do you transfer point specific loads into the billet without tearing the cf skin - like fastner/threaded ?. Also any worry about electrolysis corrosion of the steel fibers over time sinceost CF is somewhat conductive ? Thanks again for sharing your expertise. CLM




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[clmenz]

Peter, reading your initial description of the billet "recipe", initially seemed you were setting up a typical sandwich construction section of outside laminated skins (high performance material)-in this case carbon fiber cloth and some form of lower density material in the middle seperating the 2 skins..ie "steel fibers (dry matrixed +eventual epoxy infusion ) inbetween faces > binding the whole billet together with the epoxy infusion of steel fibers + CF faces. I guess my duh alternative explanation is the whole billet is a dry mix of chopped C.F. + varying steel fibers all infused/bonded with epoxy forming an isotropic 22mm to 25mm plate . The images that followed suggested the "duh alternative" since I didn't see any typical black carbon fiber cloth faces. In the Milli thread l, I thought you also recently decided just using 2 sheets of steel preformed and then bonded together with epoxy forming a steel laminate for the saddle was the cost effective stiffer way to go. Is the overall current process considered proprietary ? Does this billet have one of your great stress/deflection/FEA analysis plots and any mechanical properties (? bending kpsi, tortion kpsi, Youngs mod, CTE (close to steel @ about 7 vs lower in 1-4 range) , etc How do you transfer point specific loads into the billet without tearing the cf skin - like fastner/threaded ?. Also any worry about electrolysis corrosion of the steel fibers over time sinceost CF is somewhat conductive ? Thanks again for sharing your expertise. CLM




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Peter, looking at ALL the images again I do see CF cloth in initial vacumn bag images . My bad !!! Can you share any information about the billet post infusion, also any specifics of the actual CF , steel fibers, epoxies used/suppliers. thanks

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[peteeng]

Hi Clmenz - working thru your initial Q's. I get std modulus CF cloth offcuts from a company I work with. I randomly stack those into moulds and infuse them. This has E=40GPa by tensile test at a lab. No propriety info here. Infusion is a well documented process. You can infuse lots of things, even human remains (look up plastination especially images; by the way the colours in plastination are painted on I found out as the tissue goes a pale yellow colour in the process. I have been to one of these exhibits and they are amazing). I have lots of steel fibres to use up so try to use that first. The steel fibres are those used in vehicle brake pads. I would not recommend them as a high performance material. They have not worked out as expected. They clump badly and do not acheive the packing that I want only about Vf=15-20%. Yes steel lamination is one way to go, haven't been able to do that large scale yet. When Frankie leaves the building I can start on another machine.. and then I can use updated thoughts and processes. The billet will be treated like a lump of metal or plastic and be machined with threads. I have done this before and tested the threads etc. The steel fibres I have placed in epoxy and concrete and put in the weather. They do rust so the parts need sealing or painting. But steel fibres aren't in the future parts box. Spacers and odd things I'll make to use up the 20kg I have... The epoxy I use is a standard infusion grade resin, most epoxy suppliers have several infusion epoxies these days. Very thin and active at room temp. Gel time at 25degC 70 mins which is a bit long. Even a 50ft boat fills up in 30mins....

Next machine I want to use generative design heavily. Now I'm comfortable in Fusion that seems to be the way to go. NASA uses AI to make hardware that is "three times better in performance" (dezeen.com)

I have sourced chopped CF but it suffers the same issues as the short steel fibres. They do not pack well. I'm about to have some metal powder samples & ALOX tested for modulus, that will end the materials development program I think. Powders pour into moulds easily and pack at 60+% volume fractions so that maybe a pathway. But steel is cheap and stiff, its hard to beat unless you have a metal printer handy. I can get steel powder... and the damping issue is mute if the machine is rigid enough plus I'm going to use input shaping damping (electronic damping) in future machines. I think I have exhausted the non-exotic material options and now have to learn [Klipper+ big tree tech ] to take advantage of electronic damping. I need say 20 minions and a test lab and a small manufacturing arm with a pleasant patron to get thru my projects faster....I have mentioned a Milli-IRB and I see Tormach have released an industrial robot so maybe the big robot is the next project. Peter

To give you an idea of the poor pack, the billet just made has a density of 2000kg/m3 so even though its "mostly" steel by weight its mostly epoxy by volume. If it were 100% steel it would weigh 9.8kg yet it only weighs 2.5kg so I doubt its very stiff. But this part is basically a damp spacer so it will be fine in that application.

[peteeng]

Hi CLM - To summarise my material development thoughts. From highest performance to lowest where the modulus is the highest weighted factor then damping and its my opinion no maths involved, its a guideline:

steel laminated E=200GPa
monolithic steel E=200GPa
intermediate modulus CF E120-140
laminated titanium E100
cast iron E100
mono titanium E100
aluminium laminated E70
granite E70-100
monolithic aluminium E70
high performance std modulus carbon fibre E=70-80GPa
random CF E40
HP glass fibre E30-40
epoxy granite E30-40
plywood E17
MDF E4
most monolithic plastics E3

exotics
beryllium 300GPa
ultra high modulus CF 300GPa

If someone approached me with a V big budget and said I want the ultimate router or mill I'd go intermediate or HM carbon fibre. I like beryllium but the paperwork and health risks are too much...

cheers Peter

[peteeng]

Evening All - I was going to work with the whole cast but decided to cut a bit off and put the rest on the shelf. I cut the end off with a hacksaw then set it up in Scoot to square the end. Now its rough squared I can frame it then level both sides, then I can finish the part. Peter

Billet 1 - You can see the 5mm off CF on the bottom and the steel top. I should have used CF on both sides as the billet has curved under exotherm..
Billet 2 - squaring up the end...

[peteeng]

Morning you lot - Sorted the spindle plate billet and checked the part. Made it a bit bigger as I had the material. May as well be in the part then make it into swarf. This will get machined next week. Have a great weekend out there you'all. Peter

[peteeng]

I'd like to add a material to the list. Its commercially available in very small quantities but one day we maybe able to make machines out of it.

steel laminated E=200GPa
monolithic steel E=200GPa
intermediate modulus CF E120-140
laminated titanium E100
cast iron E100
mono titanium E100
aluminium laminated E70
granite E70-100
monolithic aluminium E70
high performance std modulus carbon fibre E=70-80GPa
random CF E40
HP glass fibre E30-40
epoxy granite E30-40
plywood E17
MDF E4
most monolithic plastics E3

exotics
beryllium 300GPa
ultra high modulus CF 300GPa
Graphene E=1200GPa

or diamond at E=1200Gpa

[peteeng]

Morning All - Today the new spacers for the ballscrews arrived so I can back into assembling the drives. Yippee . .peter

[peteeng]

Hi All - Today I framed the CF billet and rough set it up. Checked tooling and sizes getting ready to face the billet. Then remove and plane the wasteboard then face the other side... Then I can finish the part... Peter

[mactec54]

Hi All - Today I framed the CF billet and rough set it up. Checked tooling and sizes getting ready to face the billet. Then remove and plane the wasteboard then face the other side... Then I can finish the part... Peter

It's good to see you are using better work holding, everything is evolving.

[peteeng]

Hi Mactec- Thanks - Everyday try to do a little better Peter

[peteeng]

Hi All - New controller arrived so all's here to move forward again. Yippee. Peter

[peteeng]

Evening all and Sundry - This afternoon I faced the CF billet for the spindle mount. All went well and the faces where parallel at the end so I'm happy with that. Now to profile, drill and thread the part. Frankie's new spacers and controller are now in so its very close to sawdust day... Peter

[peteeng]

Evening all - a link to the billet being faced. Peter

https://www.facebook.com/ScootCNC/vi...44206087895482

[peteeng]

Evening all - Today I nearly completed the spindle plate. It now needs to be threaded and its done. I have been using Fusion360 for a year now and its settling down to be a good system. Recently I have started using its setup sheets rather than writing my own notes. I want to keep track of cutting data do I don't have to reinvent it every so often... Anyways machining the CF/Steel billet was straightforward. Mainly used a 1F upcut carbide for the heavy work. This left a bit of fuzz with the carbon but the steel side was quite sharp... So now I can pull down the Z axis, drill to suit the spindle plate then reassemble at second fit level and make some swarf!! Getting excited... Peter

[mactec54]

Just came across this you might be interested in
https://www.degruyter.com/document/d...2022-0390/html

[peteeng]

Thanks M54 - starcrete hmmm - uses a lot of human urine and blood fractions. Going to need a lot of humans to make the components... Musk would be interested. It describes 40MPa as a high strength material! its modulus is less then plastic can't imagine making big structures from it but then gravity is less. I'll read it a bit more. Thanks again Peter

[mactec54]

Thanks M54 - starcrete hmmm - uses a lot of human urine and blood fractions. Going to need a lot of humans to make the components... Musk would be interested. It describes 40MPa as a high strength material! its modulus is less then plastic can't imagine making big structures from it but then gravity is less. I'll read it a bit more. Thanks again Peter

I don't think that is the case although this is all connected to the same article.

The engineers believe future space construction will need this solution.
Potato starch replaces human blood as a key ingredient in the new recipe.
The University of Manchester's new “StarCrete” is twice as strong as traditional concrete, making it a potential solution as a building material for Mars. Add in some extraterrestrial dust and potato starch, and you have a potentially revolutionary new material.

In an article published in the journal Open Engineering, the research team showed that potato starch can act as a binder when mixed with simulated Mars dust to produce a concrete-like material reaching a compressive strength of 72 megapascals (MPa), over twice as strong as the 32 MPa seen in ordinary concrete. Of course, mix in moon dust instead and you can get StarCrete to 91 MPa.