[jono5axe]

\r\n \r\n I would suggest that you consider polymer concrete rather than cement concrete. Epoxy concrete will be stronger and give you a nicer surface. Epoxy or polyester concrete/granite (also known as engineering stone) can be machined, ie for bed-ways (or for kitchen benchtops which is an everyday thing). Cement concrete is not very dimensionally stable due to it containing water. Epoxy concrete will be more stable, and even polyester resin should probably be ok, as if the aggregate mix is correct (not excess resin) then the aggregate matrix cannot shrink on cure (polyester has shrinkage on cure). Polyester is cheaper than epoxy. Polymer resin concrete will hold the fasteners/inserts better. You can also add fibres to polymer concrete if you want it stronger again.
\n
\nFor which ever concrete you choose, you should select a type of aggregate stone that is very old and stable, not just any old aggregate that the concrete company is using that day.
\n
\nLooking at you cad renderings of the base and column, they appear to be completely solid lumps of concrete. I would suggest considering using polymer resin concrete and not making the parts completely solid, rather say 50mm thick main sections with support webs etc, similar to if it was a cast iron design.
\n
\nIf you really want to avoid machining, you might be able to come up with some idea how to mold the bedways off the machined steel ones that you have already set up? But in my experience that type of exercise is very time consuming.
\n
\nRegarding joining the parts, just think about it the same as if it were steel / aluminium / cast iron - use shims and bolt it or epoxy grout it (epoxy grout has sand or similar load bearing particles in it). But you need to consider the relatively reduced strength and hardness of the concrete when designing the joint / bearing areas.\r\n \r\n

[stef110]

\r\n \r\n Thanks for you reply jono,
\nUHPC is not an ordinary concrete, they already use it to build machines bases, here is an example of a company how made machine parts with it: https://www.sudholt-wasemann.de/mach...e-of-uhpc.html
\n
\nThe parts i drawed are mostly massive im trying to make the column a bit hollow now but its easier to just make an massive casting and the extra weight will only be good to absorb vibrations right?
\nI have a question about the height of the machine bed is there any giving recommend height for that? On my current machine the bed is around 110cm above the ground.
\n
\nstef
\n
\nstef\r\n \r\n

[ianagos]

\r\n \r\n

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\r\n

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\r\n \r\n \r\n

Thanks for you reply jono,
\nUHPC is not an ordinary concrete, they already use it to build machines bases, here is an example of a company how made machine parts with it: https://www.sudholt-wasemann.de/mach...e-of-uhpc.html
\n
\nThe parts i drawed are mostly massive im trying to make the column a bit hollow now but its easier to just make an massive casting and the extra weight will only be good to absorb vibrations right?
\nI have a question about the height of the machine bed is there any giving recommend height for that? On my current machine the bed is around 110cm above the ground.
\n
\nstef
\n
\nstef

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\nHow do you like the table at 110cm? My larger vmcs (fadals) have table height around 85cm.\r\n \r\n

[pippin88]

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Thanks for you reply jono,
\r\nThe parts i drawed are mostly massive im trying to make the column a bit hollow now but its easier to just make an massive casting and the extra weight will only be good to absorb vibrations right?

\r\n \r\n

\r\n

\r\n

To simplify things, there are 3 important factors that determine resonance / vibration of a structure:
\r\n1. Stiffness - increasing stiffness increases the natural frequency.
\r\n2. Mass - increasing mass decreases the natural frequency.
\r\n3. Damping - damping is generally a property of the material
\r\n
\r\nIncreasing mass lowers the natural frequency of a structure. Lowering the natural frequency is generally bad. The ideal machine tool has natural frequencies that are above any frequency it will actually encounter in use.
\r\nIncreasing mass can increase stiffness, e.g. by increasing the thickness of a section. Increasing stiffness is good. However, you can actually To increase stiffness it is usually much more effective to increase the size of a section. Stiffness mostly comes from placing mass as far as possible from the neutral axis.
\r\n
\r\nThe ideal is to increase stiffness while lowering mass, and retain damping.
\r\n
\r\nWhere you do not have a particular size constraint, you are much better off making a bigger hollow column than a small solid column of the same mass.
\r\n
\r\nJust throwing extra weight on does not absorb vibrations. You may actually increase the chance of a machine tool vibrating if you lower the natural frequency into the operating range of the machine tool.\r\n \r\n

[jono5axe]

\r\n \r\n

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\r\n

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\r\n \r\n \r\n

Thanks for you reply jono,
\nUHPC is not an ordinary concrete, they already use it to build machines bases, here is an example of a company how made machine parts with it: https://www.sudholt-wasemann.de/mach...e-of-uhpc.html

\r\n \r\n

\r\n

\r\n

Yes what you say is correct, but uhpc is still a cement concrete with water and what I posted is also correct. 15 MPa is not that impressive. Re solid sections, if you look at other video of concrete / polymer concrete bases being manufactured there are many that are not completely solid (but rather more like an old school cast iron sand cast machine base).\r\n \r\n

[jono5axe]

\r\n \r\n It is possible that that Sudholt-Wasemann Nanodur®-concrete E45 has a water-based polymer additive. But all uhpc does not necessarily have that. All uhpc is not equal.
\n\r\n \r\n

[rocketflier]

\r\n \r\n Sihts about to get real!\r\n \r\n

[RotarySMP]

\r\n \r\n Very impressive build. Thanks for sharing it.\r\n \r\n

[stef110]

\r\n \r\n Finally its done it took 4,5 hours of mixing stamping and vibrating to complete the mold. In it there is now 265kg of silimix and 29,5 kg of epoxy separated in 11 mixing batches.
\nNow its time to wait and let the epoxy cure. Im so curious how the casting is gone look like.
\n
\nStef
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[rocketflier]

\r\n \r\n Looking forward to seeing those forms stripped!! Fingers crossed!!\r\n \r\n

[arizonavideo]

\r\n \r\n I\'m looking forward to seeing it set up too.
\n
\nIt is really nice to see someone step up and do something that has not been done too many times before.
\n
\nI hope the results prove good.\r\n \r\n

[pippin88]

\r\n \r\n Looking forward to seeing the results!!!\r\n \r\n

[stef110]

\r\n \r\n This afternoon i carefully try\'d to brake away the mold, Im super surprised how easy it went The release agent did a super good job.
\nThe thread inserts came out super nice, cant wait to turn this monster around an get the rest of the mold off.
\n
\nStef
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[AutomatedIngen]

\r\n \r\n Wow it came out really good.... Next part is going to be the column?\r\n \r\n

[stef110]

\r\n \r\n This weekend i want to build the frame where it gone stand on.
\nIm still struggling with column design mostly because im not sure how i want to do the head. After this casting i really think i can do my head also with EG.
\nBut Im not sure how i gone mound my carriages and still be able to adjust the tram of the mill.\r\n \r\n

[AutomatedIngen]

\r\n \r\n

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This weekend i want to build the frame where it gone stand on.
\nIm still struggling with column design mostly because im not sure how i want to do the head. After this casting i really think i can do my head also with EG.
\nBut Im not sure how i gone mound my carriages and still be able to adjust the tram of the mill.

\r\n \r\n

\r\n

\r\n

I\'m actually taking on a project with epoxy granite as well, I\'m about to order the materials for me to make my mold soon. Your project has given me the inspiration I need to get back to my designing.
\n
\nI too want to design my head to be EG but the difference with my machine is I will be casting the EG around the original cast iron casting (I have a PM-940 Mill).
\n
\nCould you design the column and head in the similar manner as you did the base, by putting steel for the rails of the column which can be machined after and put steel squares on the back of the EG head for your linear blocks to attach to after being machined? That way you can square all of your components and only if absolutely necessary you can put shims between the mounting points of the linear blocks for any further adjustment.
\n
\nHow I envision building my EG head is in two separate pieces. One piece will be the moving head and the next will be a mount for the spindle which will get bolted to the moving head. Similar to a configuration on a CNC router. That way I can adjust the tram of the moving head to ensure it is perpendicular to the X & Y axis, then adjust the tram of the spindle to ensure it is perpendicular to the Z.
\n
\nHope the above helps, if not I can post post pictures of my idea with your permission, as I have not created a thread yet.
\n
\nI have been meaning to ask, what\'s the reason for all the threaded inserts on the sides? I get the ones on the bottom are for your alignment pads but what about the ones on the sides?
\n
\nAlso what did you use to vibrate the mold?\r\n \r\n

[stef110]

\r\n \r\n This evening we flipt this 350kg beast. And pulled off rest of the mold. Amazing how it all turned out i never expected to be this smooth.
\nNext thing to do is the frame, then lift this beast on the frame and then do a post cure with a heater underneath it.
\n
\n@ AutomatedIngen
\nAll those side screws are there for mounting the enclosure there are probably more bolts in there then necessary but who cares.
\nI get your idea about the head made from 2 pieces but i like to make mine out off one single piece i think.
\nI would like to see your head design to get some inspiration
\nFor the vibration i just hired a concrete vibrating needle and putted it in the EG.
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[vakeiros]

\r\n \r\n looking great mate, keep us posted! I should receive my missing motors tomorrow (5.5kw spindle servo and a 400W absolute servo for the 4th axis), hopefully I will have my castings done by the end of the month!!! have lots of work in hands at the moment but all the funds available for the rest of the build...\r\n \r\n

[pippin88]

\r\n \r\n Great work!
\n
\nAre you going to fill in the steel X axis with epoxy granite for damping?\r\n \r\n

[rocketflier]

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Great work!
\n
\nAre you going to fill in the steel X axis with epoxy granite for damping?

\r\n \r\n

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\r\n

Placement of the holes suggest no, but you could drill from the side and fill with sand.\r\n \r\n

[stef110]

\r\n \r\n No the X saddle will be just steel like it is now.
\n
\nThe base now have been baked for 26 hours at a max temp of 55 degrees in the end. Now it will be waiting on some measuring devices and epoxy to try to make the steel plates flat so i can mount the rail.
\nIn the mean time im working on the Column design.
\nIm in contact with some Chinese sellers for a big servo for driving the spindle. currently im doubting what to do my BT30 spindle has a max rpm of 6000 but maybe in the future i will update it to higher rpm.
\nNow the servo i can buy will be or 8000 rpm or 12000 rpm but it comes with a 390 dollar higher price. On my current mill i also have a 6000 rpm spindle which seems enough but more is always better.
\nWould it be smart to already buy a high rpm spindle or just stick to an 8000 rpm max and use that money for something else.
\n
\nstef\r\n \r\n

[AutomatedIngen]

\r\n \r\n

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No the X saddle will be just steel like it is now.
\n
\nThe base now have been baked for 26 hours at a max temp of 55 degrees in the end. Now it will be waiting on some measuring devices and epoxy to try to make the steel plates flat so i can mount the rail.
\nIn the mean time im working on the Column design.
\nIm in contact with some Chinese sellers for a big servo for driving the spindle. currently im doubting what to do my BT30 spindle has a max rpm of 6000 but maybe in the future i will update it to higher rpm.
\nNow the servo i can buy will be or 8000 rpm or 12000 rpm but it comes with a 390 dollar higher price. On my current mill i also have a 6000 rpm spindle which seems enough but more is always better.
\nWould it be smart to already buy a high rpm spindle or just stick to an 8000 rpm max and use that money for something else.
\n
\nstef

\r\n \r\n

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I\'ve always tried living by the principal of buying the best of what you can afford at the time because it increases the longevity of you using that item and not having to purchase the same or similar item again.
\n
\nHaving said that my suggestion would be to buy a high rpm spindle.\r\n \r\n

[mactec54]

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\r\n \r\n \r\n

No the X saddle will be just steel like it is now.
\r\n
\r\nThe base now have been baked for 26 hours at a max temp of 55 degrees in the end. Now it will be waiting on some measuring devices and epoxy to try to make the steel plates flat so i can mount the rail.
\r\nIn the mean time im working on the Column design.
\r\nIm in contact with some Chinese sellers for a big servo for driving the spindle. currently im doubting what to do my BT30 spindle has a max rpm of 6000 but maybe in the future i will update it to higher rpm.
\r\nNow the servo i can buy will be or 8000 rpm or 12000 rpm but it comes with a 390 dollar higher price. On my current mill i also have a 6000 rpm spindle which seems enough but more is always better.
\r\nWould it be smart to already buy a high rpm spindle or just stick to an 8000 rpm max and use that money for something else.
\r\n
\r\nstef

\r\n \r\n

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\r\n

After doing a great job of the base and you are not having the rail mounting surfaces machine, mounting them on epoxy is not a good idea, all your rail and mounting areas need to be machined\r\n \r\n

[Eldon_Joh]

\r\n \r\n i recommend just lapping the top of the X axis rails flat. epoxy a strip of steel just as wide as the rails so you don\'t need to remove any more metal than necessary.
\n
\nto get the twist out of it, you need a straight edge, 4 referance points at the ends of the rails, and a dial indicator in the center. the indicator should read the same across both diagonals. -' + '-you do not need a precision straight edge, you can use a 2x4 block of wood with 3 mostly flat gauge blocks epoxied on the surface.. mark the locations of where the referance points on the straight edge touch the ends of the rail mounting surfaces and the dial indicator needs to be located exactly where the two diagonals cross... it doesn\'t have to be perfect but if the location of the dial indicator is off then imperfections in the straight edge begin to matter.
\n
\nall the straight edge has to do is compare the three points with the other two points, it doesn\'t have to be straight. you can also use the center point where the diagonals cross as a pivot point and measure twist with feeler gauges at the corners.
\n
\ngetting the convex or concavity out of the rails is a bit more work, but if you can get it to .0005" across 18" (comparing with a 100$ 12x18 surface plate) then you can get it to .002" over 36 inches.. may be good enough.
\n
\n
\none of the problems with pouring epoxy is the bolt holes are too far apart (unless you drill and tap a bolt every 30mm. for 15 and 20mm profile rails they are too flexible for 60mm bolt spacing for sure and you will probably see .0005" disappear into the epoxy under each bolt. ) but since you are using 25mm rails iirc you may not have a problem with 60mm bolt spacing.\r\n \r\n

[stef110]

\r\n \r\n @ Mactec54
\nIf you gone pay the transport and the machining i would really like to do it that way...
\n
\nI know machining will be the easiest way and the best way but those parts are to heavy to move around easily for me. Let me first try i with epoxy and if that fails or not giving the right result i can always consider machining.
\n
\nI have ordered a straight edge and epoxy few days ago. My plan is to use the way Markus Müller did on his huge EG milling machine.
\nHe pressed his straight edge in the epoxy to get an almost flat surface an from there he scraped and sand the surface to get it perfect flat.
\nI ordered the same epoxy as him, that one is special designed for this applications in machine building environments.
\n
\nhttps://www.youtube.com/watch?v=xtFzb6r6Np8
\n
\nStef\r\n \r\n

[mactec54]

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@ Mactec54
\nIf you gone pay the transport and the machining i would really like to do it that way...
\n
\nI know machining will be the easiest way and the best way but those parts are to heavy to move around easily for me. Let me first try i with epoxy and if that fails or not giving the right result i can always consider machining.
\n
\nI have ordered a straight edge and epoxy few days ago. My plan is to use the way Markus Müller did on his huge EG milling machine.
\nHe pressed his straight edge in the epoxy to get an almost flat surface an from there he scraped and sand the surface to get it perfect flat.
\nI ordered the same epoxy as him, that one is special designed for this applications in machine building environments.
\n
\nStef

\r\n \r\n

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The problem with the epoxy it is to soft and as you torque the rail capscrews to the correct torque the rail will sink into the epoxy, if you new you where going to do this then you should of machined them first and then just scraped them after
\n
\nA lot are doing this but it is never going to be as good as a machined surface\r\n \r\n

[jackjr-123]

\r\n \r\n Here we go again with the ridiculous claims... "epoxy is too soft".
\n
\nI did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
\nThe difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").\r\n \r\n

[hanermo]

\r\n \r\n Agree completely.
\r\nEpoxy is more than hard enough - industrial epoxy.
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\r\n \r\n \r\n

Here we go again with the ridiculous claims... "epoxy is too soft".
\r\n
\r\nI did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
\r\nThe difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").

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[stef110]

\r\n \r\n Im pretty sure the epoxy will be way good enough for me. I gone use the DWH 310FL.
\nDon\'t forget its just a hobby machine and in any case it will be way better then my current machine and i don\'t have to fly to the moon with it.
\nI hope the epoxy and parallel will arrive soon cant wait to try it.\r\n \r\n

[mactec54]

\r\n \r\n

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\r\n \r\n \r\n

Here we go again with the ridiculous claims... "epoxy is too soft".
\n
\nI did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
\nThe difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").

\r\n \r\n

\r\n

\r\n

\nMy clams we can back it up with real life testing FEA with I have and use will not give you the correct numbers
\n
\nSo your numbers are total Bs We did the testing in real examples and compared 3 different epoxy\'s even the hardest Moglice ( Expensive ) that they use for rebuilding machine way\'s and there was deforming of .0004" to.0006" with a 18" rail mounting, the other epoxy\'s that you suggested where even worse, with having this amount of deforming is to much for any quality linear rail mounting, at every SHCS mounting point ( every 60mm ) there was deforming of the rail it\'s self
\n
\n
\nThe max hardness of flexible epoxy\'s is 35-60 D shore hardness
\n
\nRigid Epoxy\'s is 70-90D shore hardness still a soft working surface
\n
\n
\nhttps://theepoxyexperts.com/shore-hardness/\r\n \r\n

[jackjr-123]

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Im pretty sure the epoxy will be way good enough for me. I gone use the DWH 310FL.
\nDon\'t forget its just a hobby machine and in any case it will be way better then my current machine and i don\'t have to fly to the moon with it.
\nI hope the epoxy and parallel will arrive soon cant wait to try it.

\r\n \r\n

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Of course it is. Markus proved it with his 5 tons, micron precise VMC.\r\n \r\n

[mactec54]

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Of course it is. Markus proved it with his 5 tons, micron precise VMC.

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\nHe has not proved anything, I\'m sure it is moving as I write this, it will never be stable no matter what he say\'s, it\'s all about the lack of compressive strength, with a shore of only 88D your bones in your body have a shore of 100D to give you a comparison\r\n \r\n

[Eldon_Joh]

\r\n \r\n

\r\n

\r\n

\r\n

\r\n \r\n \r\n

Here we go again with the ridiculous claims... "epoxy is too soft".
\n
\nI did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
\nThe difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").

\r\n \r\n

\r\n

\r\n

i believe that. but my comment regards my own experience of bolting a 20mm rail to about 1/8" or 3mm of system 3 mirror coat.
\n
\nunder a 20mm rails there are only two, about 5 or 6 mm wide contact patches.
\n
\n
\nand you have to figure the bolt torque is only going to be spread out at a 30degree cone away from the bolt. it won\'t be evenly spread out across a 50mm wide area. also you have the surface roughness of the epoxy to compress.
\n
\nanyhow, its totally acceptable for some applications but not for others.\r\n \r\n

[stef110]

\r\n \r\n Can we end this endless discussion about epoxy will be fine enough or not. It will be my choice and my decision is made.
\n
\nDidn\'t make a lot of visible progress last week. Today i moved the base to its final place where it will be put together.
\nI ordered the 12krpm servo spindle and some measuring tools also arrived this week.
\nThe design of the column is also almost done so i can start making the steel inserts and base plates this week.
\n
\nStef
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[jackjr-123]

\r\n \r\n Your statements are contradictory. Moglice P and DWH 310P have the exact same shore hardness and E-modulus. How can one perform worse than the other?
\nI don\'t know how you performed your tests, but the epoxy thickness and bolt tightening torque have obviously a huge influence.\r\n \r\n

[mactec54]

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Your statements are contradictory. Moglice P and DWH 310P have the exact same shore hardness and E-modulus. How can one perform worse than the other?
\nI don\'t know how you performed your tests, but the epoxy thickness and bolt tightening torque have obviously a huge influence.

\r\n \r\n

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\r\n

Yes correct I should of said the epoxy that most use is way softer than the Moglice we tried was the best, what number do you have for your shore hardness because we can test that
\n
\n2mm to 2.5mm was the recommended thickness for testing which did not change the out come, there is another builder doing a very large 5 Axes machine who is an epoxy expert will tell you the same as I have\r\n \r\n

[Azalin]

\r\n \r\n This is going to be a nice machine.
\n
\nIs the 12k servo you ordered for the spindle?
\n
\nSent from my MI 5s Plus using Tapatalk\r\n \r\n

[stef110]

Finally its done it took 4,5 hours of mixing stamping and vibrating to complete the mold. In it there is now 265kg of silimix and 29,5 kg of epoxy separated in 11 mixing batches.
Now its time to wait and let the epoxy cure. Im so curious how the casting is gone look like.

Stef