Stell frame cnc 1500X1000. Adjustable table your opinion please

[Neale]

I've been working on my machine this evening, and I think that we are a very similar stage of build! I was levelling the frame of my machine (similar size - cutting area about 1500x750) and thinking about epoxy. I have already bought my epoxy (Reactive Resins low-viscosity with slow hardener) but they say that it should not be used below 8C. In my part of the UK at the moment, that's about the night-time temperature and daytime is only about 12C (and probably slightly cooler in my garage).

As well as I can measure it, I have a dip in my rails of about 1.3mm in the centre. Not as accurate as I would like - not sure if it was a bend in the original 100x50 box sections, or welding distortion - but I think that that will be fine with epoxy. However, I could shim it, if I can find some suitable material. Epoxy has the advantage of also bringing both rails into the same plane, of course, which would be much more difficult with shims (tapered shims, anyone?). What I don't know is what kind of tolerance you need to work to with Hiwin rails - what kind of relative twist in the two rails is OK? If both rails are perfectly horizontal in both planes but one is, say, 1mm higher than the other, would this matter? On my machine, that is a twist in the bearing block of about 0.06deg, or 0.001mm across the rail. Doesn't sound like a lot to me, but I have no practical experience of the real-world tolerances on these things.

I'm planning to epoxy first and drill/tap through the epoxy and rail later. My feeling is that this will be easier, and certainly better than trying to remove the epoxy that has leaked into the tapped holes.

[Boyan Silyavski]

I've been working on my machine this evening, and I think that we are a very similar stage of build! I was levelling the frame of my machine (similar size - cutting area about 1500x750) and thinking about epoxy. I have already bought my epoxy (Reactive Resins low-viscosity with slow hardener) but they say that it should not be used below 8C. In my part of the UK at the moment, that's about the night-time temperature and daytime is only about 12C (and probably slightly cooler in my garage).

I have done the first machine at 14-16C, but i believe any lower is not good idea.

What I don't know is what kind of tolerance you need to work to with Hiwin rails - what kind of relative twist in the two rails is OK? If both rails are perfectly horizontal in both planes but one is, say, 1mm higher than the other, would this matter? On my machine, that is a twist in the bearing block of about 0.06deg, or 0.001mm across the rail. Doesn't sound like a lot to me, but I have no practical experience of the real-world tolerances on these things.

For 20 size z1 preload :
-mounting surface parallelism 0.02mm
-block mounting surface 0.01mm

It will withstand more, just loosing life expectancy.

I'm planning to epoxy first and drill/tap through the epoxy and rail later. My feeling is that this will be easier, and certainly better than trying to remove the epoxy that has leaked into the tapped holes.

[vargai]

bearing block of about 0.06deg, or 0.001mm across the rail.

any CNC producer can be happy with this. I am just wonder how did you measured this 0,001 mm?

[Boyan Silyavski]

Something came to my mind. When doing the epoxy thing, they both should be one temperature with the frame. Means Not pour and then turn the heater on as it would be a disaster. bring a heater to the workshop, turn it on for a couple of hours so the epoxy and the frame will be one temperature. Then leave it for overnight while the epoxy is cured.

[vargai]

regarding to the epoxy itself it seems good thing against vibration too .
Pls advise about the strength and hardness with comparing to ie. AL.
When one bolts onto a rail with M6-is its compression negligible?

[Neale]

any CNC producer can be happy with this. I am just wonder how did you measured this 0,001 mm?

I didn't measure this directly. It's based on a difference in heights of rail of 1mm and a rail spacing of 1m. Looking at the hiwin catalogue, I think they say that the bearing blocks can tolerate a slight rotation around the rail, and a height difference of 0.26mm (20mm rail, 1m spacing). This is a lot more than the figure that Silyavski has given, but I might have misunderstood something.

[vargai]

I didn't measure this directly. It's based on a difference in heights of rail of 1mm and a rail spacing of 1m. Looking at the hiwin catalogue, I think they say that the bearing blocks can tolerate a slight rotation around the rail, and a height difference of 0.26mm (20mm rail, 1m spacing). This is a lot more than the figure that Silyavski has given, but I might have misunderstood something.

Only the 1 micron (you wrote 0.001mm) seemed to tight. The angle is correct, the level deviation on 20 mm is 0,02 as my dwg says
It is one magnitude bigger but I do not think it has too big impact on a router-by the way I would not be satisfied either with 1 mm on 1 m because deviations accumulates according to the Murphy catalogue

[Neale]

Perfectly correct, Vargai - I forgot to multiply the "1 in a 1000" ratio by the width of the rail. I've slapped my own wrist...

[vargai]

Perfectly correct, Vargai - I forgot to multiply the "1 in a 1000" ratio by the width of the rail. I've slapped my own wrist...

I would not have intact body portion so just meant to understand you

[ba99297]

Hello everybody
I am happy that i restart my project
Many things had happened during the last year, that make me stop any kind of progress
That until August when i decide to restart, but first i had to make some changes in my working place
The most important was that the floor was worn and all these years was a source of dust.
That was the situation before


I decided that i must lay tiles and keep one place with some kind of heavy duty concrete, in order to be able to weld, as tiles even if they are very hard though they are not suitable for such jobs
First i had to clear the floor from old paint
Two days of water blasting with my karcher finally make possible this


Then i begun to lay tiles

It was the first time for me that i lay tiles in such a big scale ( 80 m2), and i lay them diagonally
Finally the result is this



I had the chance to paint. I decide to paint with oil paint the first one meter and the rest with water color

Then i had to make the "baby room". Yes thats right!!!! the place that i will put the cnc. I had some old aluminum doors and i dont want to sell them for scrap. I also had some drop ceiling parts, so i use them all and i made this

Yesterday i move the frame and all the components in order to restart building


As you can see the machine is rolling on 4 wheels. That makes the removal of the machine very easy
Finally the "baby" get in the new house

So Today i start working again on the machine.
Nice feeling
First i had to cut some ruber parts for the adjustable feets


So far that is my progress
I will continue tomorrow
Thanks for your time
Vagelis