Newbie Machine Build Log (Fancy Machine)

[Fancy]

Hey all, I am Mos 24 yr old from Egypt. I've been stalking this forum for a really long time :D and been wanting to make a moving gantry CNC and finally i have the time and money to build one. I was thinking of a similar design to joe harris's design where the y rails are elevated a distance above the table eliminating side plates but i was thinking of a beefier Gantry. I was thinking of a 160mm rectangular or square steel tubing with a reasonable thickness to it. I want the machine mainly for cutting aluminum and other various metals to 0.05mm tolerances but i need the work area which is why i went with a moving gantry and not a fixed one. I am thinking the work area would be 800x1200mm. Another thought i had for the gantry was making a welded steel skeleton for an epoxy granite gantry but I haven't seen anyone attempt that and most the fixed gantry machines have small gantry span making me worry that there could be alot of deflection for a 800mm span. Please share your thoughts on the ideas i proposed, Thanks in advance.

[mekanik]

Hi Fancy
Have a read of this.
http://www.mycncuk.com/threads/11617-AVOR-%C2%96-a-steel-framed-medium-size-router/page2?highlight=AVOR
The gantry is very rigid,note the use of the two sections welded together this is far stronger than the equivelant size box section, would think granite epoxy would be to heavy.
Regards
Mike

[Neale]

Although I intended the machine that Mekanik has linked to for mainly wood and maybe aluminium, I have recently been machining steel with it. Not the ideal machine, but using a small cutter (because of the high minimum spindle speed - I can run a 2.5mm cutter at 5000 rpm) I have been able to make profile cuts in 3mm mild steel. DOC is typically 0.2mm but that mainly because of the fragile cutters. I have just ordered some short series carbide cutters which should be much stiffer.

This is more "getting away with it" than using the machine within its comfort zone but it says something about the gantry design.