[Momentz]

Hi Guys
Thought I'd share my fixed gantry mill build. I just stared assembling the steel to support the base, going to use a fibre reinforced uhpc.

Specs
650x650x300mm XYZ
Table is 585x400mm
Base is 200mm thick
Gantry is 300mm thick
Estimated weight according to volume and steel parts is around 900kg

Anyway here are some pics and feel free to follow along.


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[peteeng]

Hi Momentz - What UHPC are you going to use? Where are you in OZ? Looked at your profile your in Port - I'm north of you near Qld border...Keep up the info. If possible publish images in the thread. The links time out and die at some point... I'm about to cast some parts in SIKA-3350 Peter

[Momentz]

Hi Peteng
I am in Albury these days.

Thinking about using a premix called Dingo Maxpro, it's got the glass fibres in it as well as stones, plasticiser, fly ash and Portland cement etc. The reason for going with this is purely costs, I was thinking epoxy granite but the cost would be 3 maybe 4x more.

The shrinkage is 0.05% so hopefully after 30 days it's done what it needs to do then I can work on leveling the linear rails.

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[peteeng]

Ho Mom - Dingo is a 100% Portland cement. Probably not a good idea to use it as it will crack over time. Look at grouts vs concrete. Lanko 701 is available at Bunnings and is a class C double expansion compensated grout. Won't crack over time and is probably a little stiffer then Dingo. Peter

https://www.bunnings.com.au/lanko-20...uting_p0967325

[Momentz]

Ho Mom - Dingo is a 100% Portland cement. Probably not a good idea to use it as it will crack over time. Look at grouts vs concrete. Lanko 701 is available at Bunnings and is a class C double expansion compensated grout. Won't crack over time and is probably a little stiffer then Dingo. Peter

https://www.bunnings.com.au/lanko-20...uting_p0967325

100% ? When I emailed them they said it had other components like the glass fibre, plasticiser, 5 to 16mm stones etc

The other one I was thinking of was cement Australia pro-50, the recipe for that looks the same as the open uhpc recipe.

Grouts are to expensive for the budget, at that price I may as well go epoxy granite.

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[peteeng]

Hi Mom - Well your building an expensive machine, once all the $$$ are added up and its the bones and DNA of the machine. The extra pro is a basic Portland again it does not have drying or plastic compensation so expect it to move a bit when curing and 30 days plus later it will possibly crack.. You can add a lot of aggregate to the grout so its half the price or better. You get what you pay for... Peter

glass fibre is used for crack control so there's an admission it's going to crack!

[Momentz]

Hi Mom - Well your building an expensive machine, once all the $$$ are added up and its the bones and DNA of the machine. The extra pro is a basic Portland again it does not have drying or plastic compensation so expect it to move a bit when curing and 30 days plus later it will possibly crack.. You can add a lot of aggregate to the grout so its half the price or better. You get what you pay for... Peter

So when you say pure Portland cement? You saying that's the only binding agent or? Because it has sand and aggregates etc.

So the grout doesn't have any aggregate? Can you share your findings and what makes a good mix as well as price on filling up a base that's 200L In Volume?

I've just seen others use basic cement with good results.

You've obviously done your research and Im still in the initial stages but moving quick so your knowledge would be much appreciated.



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[peteeng]

Hi Mom - Yes the Portland component is the active component. Sand, aggregate etc are not active just fillers. Unfortunately, Portland cement requires excess water in the mix to make it flow. This excess water ie water that is not required for the chemical reaction means the material volume is greater at cure than it should be. The excess water leaves the material over time and this leads to shrinkage and inevitable cracks. A plasticiser can be added which aids fluidity but does not take part in the reaction and just stays in the material. There are concretes (some called grouts) based on calcium sulphoaluminate (CSA) CSA based concretes are fluid at the correct water ratio for the reaction so do not exhibit drying shrinkage. Grouts either are 100% CSA or a blend of CSA and Portland (to reduce cost)

BluCem-CSA-Cem-LR-R2.pdf (bluey.com.au) Bluey have been very helpful technically and they have a suitable mix. HE80-AG or use HE80 and add your own aggregate.

Basic cement can be used but unfortunately it micro cracks and seriously cracks over time due to drying shrinkage. Its best to use a compensated concrete to build your machine. I have made a few different types of epoxy granite and have had them tested for their modulus with poor results. I personally would not go down this path. Epoxy is 3GPa stiffness and concrete starts at 30GPa so its well ahead and cheaper. Aggregate, sand is about 60GPa and blue metal is a bit stiffer. If you add blue metal to concrete it gets to 40GPa. My EG tests show <20GPa which is very poor. I use the term grout to separate it from std concrete. Std concrete design is all about crack control using steel reo or these days plastic, glass or steel fibres. I have also made epoxy and grout samples using high ratios of steel fibres with poor results.

I'm about to make some more high modulus grout samples to test, the grail hunt continues.

So I would use a good quality grout such as Bluey, Lankor or Sika and add aggregate such as blue metal. Use 5mm or 10mm at a high volume ratio. Do some test blocks to figure out max aggregate addition to improve modulus and reduce cost or use say HE80-AG out of the bag and let them worry about the chemistry.

Some of these comments are simplified to KISS.

Good luck - Peter

CSA is classified as "cement" so in some data sheets it maybe noted as cement. If the company wants to emphasis its CSA then its noted as CSA. If it says portland then its definitely portland. Granite or blue metal aggregate is over a billion years old so its about the right age to be stable. So use it well.

[Momentz]

Thank Pete for the in depth reply.

Do you have a basic recipe?

30% grout ???
50% 5- 10mm aggregate ???
20% silica sand ???
Just pulling figures out of the air here lol

I just need a base line to calculate costs


The original plan was going to cost around $260 (20 Bags) for the base with the dingo Maxpro but that's likely to fail.

Now with going grout , buying 20 bags will cost $800 but if it can be loaded with aggregate and that cost can come way down then it's an option i can afford.

The reason i started this project was because I already had the steel, ATC spindle and other components laying round.

Regards
Chris

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[Momentz]

Part 2

So according to sika it says 20kg of aggregate per 20kg bag reaching over 100mpa.

Assuming I have the right data sheet for the right product.

I have about 80kg or silica sand laying eou d as well as a 20kg bucket full of glass fibres, I wonder if these components would help the mix.

Regards
Chris

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[peteeng]

Hi Mom - I wouldn't add sand but the fibres can help with strength. Glass fibre is the same stiffness as sand. Roughly 50:50 by weight is about 50:50 by volume so get some and make a test brick. sika ultra is a class C double compensated available at Bunnings. expansion is about 0.03% so if you add 50% aggregate its about 0.015% so all good there. My aim has been to get to 70GPa modulus. This means adding high modulus aggregate like ALOX 300GPa, blue metal (granite) 60-70GPa and sand 60GPa.

Granite density is about 2.6 and grout is about 2.3 so mixing by weight is about equal by volume... if your interested in the math... I would stick to a commercial product with a data sheet then you know what your getting... Comes down to cost ratios... Good luck. Peter

you need to think in terms of $$$/m3 vs weight. So you need to convert the weigh ratios to volumes if you can.

I didn't say add sand it was just to document the stiffness. If you look up the Milli thread there's years of data in there... Peter

[Momentz]

Thanks Dad
You said at the beginning you wouldn't add sand but at the end you said you would?

Could you share some ratios or % you've tested?

Regards
Chris

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[peteeng]

Hi Mom - Look here, lots of material info it turns more into a material research project near the end and still to today..... Peter

https://www.cnczone.com/forums/cnc-d...ighlight=milli

[Momentz]

Hi Mom - Look here, lots of material info it turns more into a material research project near the end and still to today..... Peter

https://www.cnczone.com/forums/cnc-d...ighlight=milli

Thanks Pete much appreciated. I might send lanko an email to see if they have a recommendation on how much aggregate can be added to there 701 mixture.

Regards
Chris

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[peteeng]

Hi Mom - Lanko on the data sheet says 10kg of agg to a 20kg bag. But the way to figure the max addition is to get a container with known volume. Fill with aggregate mix of choice. Weight aggregate. Fill container with the agg with water to the top on scales and weigh agg + water. Now you know the volume of grout that is the max that can be added to the mix as this is the volume of the water. But you need a little room around the aggregate so if you figure out that its 60% by volume aggregate which is a typical figure then back that down to 50% by volume which is a typical figure. 50% by volume is 54% granite plus 46% grout by weight. Or as an addition rate 1kg of granite to 1kg of mixed grout. This results in maximum stiffness and least cost material.... then make a sample block at that ratio and check it pours OK....Do not agitate/vibrate grout follow the instructions, Add powder to water not water to powder...

this is based on:

wet density of grout 2200kg/m3
dry density 2300kg/m3
granite density 2700kg/m3

Peter

[Momentz]

Hi Pete
How would you suggest mixing 200L of this stuff? Lanko 701 goes of pretty quickly right?

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[peteeng]

Hi - The data sheet says to place withing 20mins of mixing and has a set time of 2hrs. It also says mix for 5min. So I'd use a small cement mixer. If doing it by hand use 2 heavy plastic buckets. Mix in one then transfer to No2, scrap out No1 into No2 and mix more. Transfer back to No1 and check all mixed. (repeat if necessary) If mixed pour into mould. Do next half bag lot etc etc.. Mix grout properly before you add the agg, I have cooked a drill with heavy loaded agg so use a big drill! I now use a big impact drill works well.. Don't use on impact setting. I have only done small test pours not big pours though. Peter

[Momentz]

Here's some pictures of my table that I'll be using. It's 60mm thick and back filled with epoxy granite then just a thin layer of pure epoxy with black oxide to make it look pretty lol, Table size is 600x400mm.

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[Mr-MaW]

Looking forward to your update, if you have any difficulties in the actual production process, I am more than happy to answer for you.

[Momentz]

Looking forward to your update, if you have any difficulties in the actual production process, I am more than happy to answer for you.

Awesome thanks for reaching out.

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