Quote Originally Posted by ba99297 View Post
First of all thanks everybody for the participation to the thread.
Next i would like to introduce some of my conclusions and ask some things about all these that i have already read

1. I beam will not be used
2. For the rails support beams I am between these profiles
80X80 4 mm
80X80 5 mm
100X100 4 mm
100X100 5 mm
and for the table structure
80X80 4 mm or
80X80 5 mm
i want your advice
Look from what you started and where you jumped- 100x100x4 and 100x100x5

Read again what Dean /jazzcnc/ told you, first be sure for what you use it mainly and then decide on the thickness. Go to your local metal shop and check for your self about the 100x100x5 and 80x80x5. This is way too much. Ok, people use them but for builds that intend to cut mainly aluminum and so.



Quote Originally Posted by ba99297 View Post
My main concern of using epoxy is the aging and the temperature effect to the table. I am talking about contraction expansion. The machine will be placed at my basement where i have temperatures from 8 ( winter ) to 26 ( summer ). Would that be a problem? What will happen if one day i decide to move the machine to another place. The truth is that epoxy look a good and easy solution, on the other hand i don’t fell good if i don’t have the ability to adjust. Also do we know how epoxy reacts. It is more than sure that epoxy doesn’t have the same contraction expansion ratio as steel. I have heard that pro builders that use cast iron, leave the metal for aging for 10 years...
Thanks again everybody. If anyone has something to suggest i am anxious to hear
Don,t get me wrong, but your main concern should be squaring the rails in one plane. And choosing square supported rails, not roundish.
I assume you don't have even a straight edge and you worry about contraction and expansion. First think do you need such an accuracy, then do you have the actual means to measure it, then how much is the cost of the tools to measure it...
For wood and plastic and occasional aluminum you need much lower accuracy than you are contemplating.

I mean relax, and be careful not to make some obvious mistake. Like making a cnc for another kind of job. remember the old saying: " The machine is strong as its weakest part". I constantly meditate on this when i catch myself overbuilding