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The CNC experiment build.

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NeoTech:
Can anyone gimme some input on this;

Roller plunger limit switch or rotary roller limit switch.?

awemawson:
Magnetic proximity sensor - long term reliability - what virtually all recent professional machines use

NeoTech:
You have a link to what im looking for would be much appreciated. :)

RotarySMP:
Hi Neotech,

After I received a copy of Thomas Zietz GradingCurve.XLS, I had a look at what my local hardware store had which would be useful aggregate. From the garden section I got 4x 25 Kg bags as follows:

5-8mm pebbles - http://www.quarzwerke.at/datenblaetter/Quarzkies_ME_5,0_-_8,0.pdf
2-4mm crushed rock - (No data sheet - this stuff is sharp edged crushed rock for spreading on the icy footpath)
0.5-2mm quarz sand for improving your grass - http://www.quarzwerke.at/datenblaetter/Quarzsand_ME_0,5_-_2,0.pdf
0.1-0.3mm quarz sand for grout - http://www.quarzwerke.at/datenblaetter/ME23-Beschichtung.pdf

Cool that the local quarry which supplies them publishes the datasheets with the screen sizes. Total cost of that 100kg was about €13.

I still have some very fine alumina from making a furnace, so that will be my finest filler. It cost €16,50 for 5kg from a pottery supplier.

So without even driving the 50km to the quarry, I could pick up a ton of aggreate for about €130 five minutes from home, although the alumina would get pricy for that amount.

Using the grading spreadsheet, it gives me the following recipe to make up a liter of Polymer concrete:

Grain 5    6,35 mm   100,00   26 %   259 ml   399 gr
                  
Grain 4    3,00 mm   74,09   26 %   263 ml   403 gr
                  
Grain 3   1,00 mm   47,74   20 %   203 ml   350 gr
                  
Grain 2   0,25 mm   27,42   16 %   157 ml   243 gr
                  
Grain 1   0,03 mm   11,74   12 %   117 ml   197 gr
                  
                                100 %1000 ml   1592 gr

The two largest aggregates are wet, so I am drying some in the oven. I read that moisture has a very detrimental effect on E/G strength.

NeoTech:
 :headbang:  Very cool - i have found most of the grades as well but not the larger ones in a pebble state.. I can find coarse granite what is commonly used in concrete here in Sweden. Its not the rounded floodbed pebbles i had hoped for. I could find most of the aggregate i needed at a local flower and plants store in their outdoor section. When i said i needed about a ton in total of aggregate, they started to look funny at me.  :lol:

You have my email in a message regarding the xls file. =)

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