Concrete VMC

Yes just to make sure the bottom of the column is strong enough. Not sure if it will help the strength but i let me have a beter feeling...

Last night i started on the rail leveling experiment for the Y axis rails on my VMC build. The base is designed in that way it can be machined afterwards but since its just so big and heavy i first would like to give this way of rail mounting a shot.
I saw this method on Mark muller VMC build so i tryed to copy it as best as i could.
Let me try to describe what i did. First of all i leveled my base as good as i could. Then in the front of my machine i mounted a round bar and leveled it with the water-level.
So for each rail the straight edge can lean on one "fixed" spot.
On the other side of the rail i made a stack of thin spacers to get the straight edge level again. Then removed the straight edge and put a PVA coating on the surface that later will be pressed in the epoxy. Next step is to make a dam to hold the epoxy inside. For the first rail i just used some silicon glue since i didn't had anything else. For the second rail i just bought some isolating foam to make a nicer straight dam. The ends of the dam i used the silicon glue again. Just right before the poor starts put some silicon on the ends so it can be pressed in with the straight edge. Then its just a matter of mixing the epoxy and poor it in. Then gently push in the straight edge and put the water-level on top to check if its still level. Then let it cure after about 12 hours i was able to push the straight edge out with a gentle push.
The epoxy i used is from DWH its the 310FL its a steel filled epoxy especially designed for under grouting rails and make solid connections between machine parts.
Tomorrow when the second rail is cured i can try to do some test to see how flat and parallel those edges are. I hope im on a good way with this.

stef


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Now you're just spoiling us! :p

A bit confused. The holes in the steel bar are for the linear rail or the bolts that anchor the bar into the base? Wasn't clear in that I see holes in the first image, but then you poured the epoxy/steel over the bar.

Those holes where only there to hold the steel bars inside the mold during casting. I now screwed in a grub screw and poor just on top of it.
The holes for the rails it self i will drill later when epoxy is cured.

Started this morning with mounting the y rails to see how the epoxy turned out. After some measurements it seems the rails are on an angle now over a length of 500mm they move 0.04 from each other.
Currently the master rail has been completely drilled an taped. Tomorrow i gone drill the slave rail completely and see where im at exactly then i can try to sand the difference out.

This afternoon after waiting 24 hours i could finally demold the column. The mold came even easier off then the base mold. The column came out super nice and its a beast!
Its currently in the "oven" to have its post cure.

Stef

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Today i fully mounted the slave rail, seems there was a small high spot on the end of the epoxy after sanding that down i get my rails flat with about 0.01mm now.
After mounting the rails i mounted the spindle, the temptation was to high so i mounted the ballnut with an improvised holder and turned on the servo so see how it moves.
This is at max speed of the servo which gives a travel speed of 15 meters per minute.

This week i want to try level the Z axis ways and mabye next week i can lift the column on the base if it all goes well.

Stef

https://youtu.be/m8BoCilmnog

That is so rad

Today the spindle servo arrived, dammmmm that thing is huge bigger then i had imaged.
Its a 3,7kw servo with a max rpm of 12000 and it can peak to 5,5kw Will be enough i guess for my small endmills.
That bt30 spindle cartridge looks a bit silly now.

stef

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That servo looks huge. I believe you can use any type of tool with it. I can use a 40mm 4 blade face cutting tool with my 1.3kw servo.

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I have some serious spindle envy now.. :(

This weekend managed to finish mounting the column rails and spindle mount.
There went something wrong with the epoxy leveling so one of the rails i needed to sand to size to make the 2 rails parallel to each other again which seems to work pretty well.
After that i was able to lift the big column on the base, now its starting to look like a real machine.

This weekend also the controller arrived to control this beast. Its an edingcnc cnc760 controller, a six axis controller with a 400khz pulse frequency also bought a extra i/o module to have more in and outputs for the tool changer.

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Very interesting project, nice job
I have a 4000# 16” gear head lathe with a 3700 watt motor (5hp) :)


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Crowbar against wall to remind the mill who's the boss.