[peteeng]

Hi All & Sundry - How's things out therein the worlds? I have been thinking about how to build some of the concrete parts that are in my head for Milli-M. The easiest thing would be to make them in two bits or I could use silicon moulds so they flex off. But I think multi part will be best. That then leads to how do I join them? Epoxy is the usual answer it bonds to concrete really well. But how efficient is the joint? So I modelled a simple beam 1500mm long 100x100 and in the middle of one I placed a 2mm thick epoxy join. Then simulate it as a cantilever. Answer is the bonded joint is just under 99% efficient. The plain beam deflects 3.379mm and the bonded one 3.405 or 99.2% efficient. The bondline is thicker then in practice so I expect that will come down in reality. So go monolithic if poss but joins are Ok in the right spot.. Peter

[spumco]

Hi Spumco - what length basalt fibres (fibers in US) did you get? Peter

12mm. I was willing to sacrifice the strength of longer fibers for workability - I only get one chance to fill this thing.

[peteeng]

Hi Spumco - 12mm is still long for fibres, good size. A 12mm fibre has an aspect ratio of about 600. Aspect ratios of <50 don't transfer strain very well so 12mm is good.... In epoxy the pull out length of a fibre is about 2mm so anything over that is fine for strength... Peter

[peteeng]

Morning All - I have been looking for a commercial benchmark for this project. Syil Mini seems to fit that bill at the moment. Syil have also moved from cast iron to EG recently for their machine bases. They say they are cast in Switzerland... Mass casting vs vacuum casting has opened up many options for this machine and others. I'm even rethinking a gantry to maximise the footprint to job ratio... So much to do. I'll have to build a wet grinder for finishing lands!! Finished off my sticky commercial jobs for the year now can plan Christmas. Happy Xmas and Ho Ho Ho to all out there... Peter

[ardenum]

Morning All - I have been looking for a commercial benchmark for this project. Syil Mini seems to fit that bill at the moment. Syil have also moved from cast iron to EG recently for their machine bases. They say they are cast in Switzerland... Mass casting vs vacuum casting has opened up many options for this machine and others. I'm even rethinking a gantry to maximise the footprint to job ratio... So much to do. I'll have to build a wet grinder for finishing lands!! Finished off my sticky commercial jobs for the year now can plan Christmas. Happy Xmas and Ho Ho Ho to all out there... Peter

for a gantry you'd have to make sure there is enough stiffness when the z axis is fully extended, this is one of the reasons I moved away from gantry. But if you wanna go this route, I can upload a step file from my strongest design.

EDIT uploaded anyway.

Single piece cast, steel cut sheet and then bent, anchored in the casting. Simple design that takes utilizes both damping of the casting and stiffness of the steel(L shaped). I designed it in EG in mind.

https://www.mediafire.com/file/zantg...sg4/model7.stp

I tried adding it here but it didn't let it through.

[peteeng]

Hi Ard - Thanks for the offer. My many HD's are littered with designs. Here's a cast base that looks good. Prefer a rigid one then a strong one Ho Ho Ho Peter

[ardenum]

Hi Ard - Thanks for the offer. My many HD's are littered with designs. Here's a cast base that looks good. Prefer a rigid one then a strong one Ho Ho Ho Peter

uploaded anyway.

Single piece cast, steel cut sheet and then bent, anchored in the casting. Simple design that utilizes both damping of the casting and stiffness of the steel(L shaped). I designed it with EG in mind.

https://www.mediafire.com/file/zantg...sg4/model7.stp

I tried adding it here but it didn't let it through.

[peteeng]

Hi Ard - nice and chunky, a bit big for a benchtop machine but can be shrunk in the shrinking machine. Peter

[ardenum]

Hi Ard - nice and chunky, a bit big for a benchtop machine but can be shrunk in the shrinking machine. Peter

The shape is key, you can scale it however you want. If I remember well, it was around 100kg just the EG, and the base was 150kg and 260mm thick with cutouts to mount things vertically, a la Datron. It was to support a 100kg Z assembly.

[pippin88]

Peter,

What percent CSA vs aggregate is ok?

For epoxy granite, ~10% epoxy is often used. Aggregate is cheap - 50c/kg in small amounts, <10c/kg in large amounts. Epoxy ~$18kg = ~$20/kg for epoxy granite.

CSA is $2.40/kg as per your figures above. What amount of aggregate will you be looking at?

The Bluey's data sheets sound attractive, e.g. BluCem HE80AG

Have you spoken with them about mix retardants / slowing agents?

[peteeng]

Hi Pippin - With Bluey you just buy the premix and off you go. I think they have retarders just send them an info request. They have been very happy to help me with data and stuff even though I'm only going to get 200kg from them at the moment. There's no need to slow them down if your just pouring into a mould? It self compacts and de-airs so no vibration needed. Gel time 30-60mins heaps...

I want to increase the CSA modulus so will test steel and Al203 additives in new year. Will do a couple of mixes to figure out max addition rates. Then do a modulus test. I wanted to bring in some UHPC from Europe but they have responded, only ship within Europe so have to go with CSA at the mo....

also RF20 is self levelling so can use that on top to create gravity level surfaces on top of the structural bulk material... Peter

Hi Pippin quick cost calc shows HE80 and EG will be about same cost per volume. But CSA is known product with known properties. Buying aggregate you don't know what your properties are, if you use sand you probably will get less then 30GPa if you add blue metal to HE80 you'll get 40GPa. So need to balance the $$$ with performance? Peter

[ardenum]

I wanted to bring in some UHPC from Europe but they have responded, only ship within Europe so have to go with CSA at the mo....

Are these, regular shops or the manufacturer of a brand of UHPC? Because if the latter, I don't know how you can even get responses back, I never bother mailing manufacturers because over the years not even one responded back. They do not like dealing with you if it's not B2B.

[peteeng]

Hi Ard - I suppose I do my research and ask the right Q's to the right people. I try to deal directly with manufacturers and deal with their technical staff not the sales staff. I have always had good response on technical stuff from companies all over the world. ... Now with email its very easy to communicate but I'm sure companies get flooded with all sorts of enquiries and they filter heavily.... For instance the UHPC I was dealing with the owner of the company and its a very large company. Similarly with local CSA company here I'm dealing with the owner of the company... Maybe I'm lucky with this sort of thing... Peter

[pippin88]

Hi Pippin - With Bluey you just buy the premix and off you go. I think they have retarders just send them an info request. They have been very happy to help me with data and stuff even though I'm only going to get 200kg from them at the moment. There's no need to slow them down if your just pouring into a mould? It self compacts and de-airs so no vibration needed. Gel time 30-60mins heaps...

I want to increase the CSA modulus so will test steel and Al203 additives in new year. Will do a couple of mixes to figure out max addition rates. Then do a modulus test. I wanted to bring in some UHPC from Europe but they have responded, only ship within Europe so have to go with CSA at the mo....

also RF20 is self levelling so can use that on top to create gravity level surfaces on top of the structural bulk material... Peter

Hi Pippin quick cost calc shows HE80 and EG will be about same cost per volume. But CSA is known product with known properties. Buying aggregate you don't know what your properties are, if you use sand you probably will get less then 30GPa if you add blue metal to HE80 you'll get 40GPa. So need to balance the $$$ with performance? Peter

Peter,

I was suspicious cost would be similar.

CSA - known material properties but unproven for precision machine tool building (as far as research that I can find). Probably easier to work with.

Vs

DIY epoxy granite - uncertain material (because DIY) but well proven in precision machine tools

[ardenum]

Hi Ard - I suppose I do my research and ask the right Q's to the right people. I try to deal directly with manufacturers and deal with their technical staff not the sales staff. I have always had good response on technical stuff from companies all over the world. ... Now with email its very easy to communicate but I'm sure companies get flooded with all sorts of enquiries and they filter heavily.... For instance the UHPC I was dealing with the owner of the company and its a very large company. Similarly with local CSA company here I'm dealing with the owner of the company... Maybe I'm lucky with this sort of thing... Peter

I guess my lifelong dream of making a fake shell corporation is the only way to get responses. On a side note Rampf advertises in it's portfolio a pre-mix of EG that's 'aimed' at DIY (https://www.rampf-group.com/en/produ...neral-casting/).

I can't comment whether it's true or just a ploy, since I don't get any replies to my emails. Would be great if someone successfully acquired it from them.

[ihavenofish]

Peter,

I was suspicious cost would be similar.

CSA - known material properties but unproven for precision machine tool building (as far as research that I can find). Probably easier to work with.

Vs

DIY epoxy granite - uncertain material (because DIY) but well proven in precision machine tools

this is kinda where i ended up with CA (CSA and CA are similar). for all the effort, epoxy is just easier, costs the same with a "known" target to achieve.

i did actually do CA and carbon fibre blending once, and the fibres did not bond in any way to the cement. they are sized (coated) for epoxy. youd need to start blending polymers with it, and then you end up with a whole new unknown region in terms of how it will behave in a machine.

.

[ihavenofish]

I guess my lifelong dream of making a fake shell corporation is the only way to get responses. On a side note Rampf advertises in it's portfolio a pre-mix of EG that's 'aimed' at DIY (https://www.rampf-group.com/en/produ...neral-casting/).

I can't comment whether it's true or just a ploy, since I don't get any replies to my emails. Would be great if someone successfully acquired it from them.

"diy" can be deceiving with things like these. the main thing most "diy" scenarios lack is a quality vibratory compactor. this is why most of the diy project dont end with good parts.

its alot different if you are just doing a "fill" though. optimal compaction and stiffness dont matter as much in that case (although its still desired).

i expect youll find the diy premix to be prohibitively expensive too, for no explainable reason. there had been another company in the past offering that (might be that ramph bought them)

[mactec54]

Are these, regular shops or the manufacturer of a brand of UHPC? Because if the latter, I don't know how you can even get responses back, I never bother mailing manufacturers because over the years not even one responded back. They do not like dealing with you if it's not B2B.

Trinic you will get everything you need to know about GFRC ( not the same name UHPC ) but most likely better with the GFRC they also have many videos from a few years ago, you can get there mix ingredients or bags of ready to use totally engineered product and can go up to 20,000 PSI average being 10,000 PSI to 15,000 PSI

[peteeng]

Hi Pippin - I'm considering CSA equivalent to UHPC. Concrete and UHPC have been used in machines for decades. If I use 50% by volume 10mm blue metal in the HE80 as suggested by Bluey to get the modulus to 40GPa then I half the price so CSA wins in the $$$ and E. If I use some AL2O3 I may improve E to 70GPa. That's my target. UHPC is available in Europe at E=80GPa...Use epoxy and I have to always use heaps of expensive high modulus filler to get to 70GPa so epoxy mineral construction will always be costly.

Blue metal is basalt so same as adding basalt fibers but in bulk form. Adding any fibres (except ones developed for concrete) to concrete is difficult due to sizing issues, need special varieties that couple to concrete and you can't add lots because they mat and clog and don't disperse well as concrete is viscous. ie different areas will be different properties. Plus if I use bulk concrete I can use self levelling versions for lands that are 30GPa stiffness vs 3GPa by using epoxy. But I intend to have a stone mason machine lands. If I get serious with concrete construction I may build a wet grinder to do that.... always another machine on the horizon.

Choose your poison Peter

Hi IHNF - UHPC and CSA do not need vibration, that's one of their attractions.

[ardenum]

"diy" can be deceiving with things like these. the main thing most "diy" scenarios lack is a quality vibratory compactor. this is why most of the diy project dont end with good parts.

its alot different if you are just doing a "fill" though. optimal compaction and stiffness dont matter as much in that case (although its still desired).

i expect youll find the diy premix to be prohibitively expensive too, for no explainable reason. there had been another company in the past offering that (might be that ramph bought them)

I did some digging "EPUMENT 140/8 B1 30kg" for 50EUR, No indication whether just the dry mix or together with the epoxy.