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For ambience alone I would rather look into fast 3D printing with recyclable/biodegradable materials.
https://www.google.com/search?q=3d+print+d%26d+terrain

Looking at your specs (2x4 ft^2) and...

With saddle you mean the tight planar spacing of two axis in regards to screws and rails as gantry mills (X and Z) and common vertical mills (Y and X) have, yes?

There was a gantry design where...

Only DIY CNC machine I know which fits that description (fixed gantry, moving table) and I have seen several videos of it milling steel and even stainless steel (small cuts though) - it's a hobby...

I got a relative who tests concrete samples from bridges and similar for a living.
They cure them at 25 deg submerged in alkaline water for 28 days I think before they break them in a press to get...

Is there a build thread of your machine somewhere please? Thanks.

To start with you do not have a 'gantry'.
A gantry is a beam that is supported on both ends, for stiffness with a traveler along that beam.

As for cutting forces and related discussions:...

Your current design is flimsy, even for wood and wastes a lot of space and material.
And to top it off you mix a gantry style mill bottom with a vertical machining center column in a CNC where the...

Electricity (Voltage Limits) Amendment Regulation 2017 - Queensland

North Queensland, Atherton Tablelands, 100km SW of Cairns. A couple houses in a very odd development from like 40-50 years ago that doesn't look like it went by the book (read: farmer cut off some...

The point is not the number of sockets in your house or flat or apartment to distribute the load.
What is important is the connection to the grid.
How many phases?
What amperage rating?
Look at...

This thread maybe?

https://www.cnczone.com/forums/mechanical-calculations-engineering-design/154101-cnc-software.html

I thought that pneumatic cylinders with an additional reservoir would be the proper solution.
The cylinder volume that changes by moving the head from top to bottom position must just be smaller...

Sounds very cool.
Do you have any images/specs/design hints I could look at please to advance my design?
From what you describe I can only comprehend 1/3rd and probably screw up the other 2/3rds in...

http://www.cnczone.com/forums/attachment.php?attachmentid=377408&stc=1

Purple - (some sort of plate) vertical stiffness for gravity bending by weight of gantry, sled, z-ram + spindle
Yellow -...

Another analysis, this time the whole base frame, with simulated crossing struts under the table by fixing the bottom faces and the bed (lower half rigid).
Total force is 50kgs, split half between...

I haven't seriously stress tested this yet, but here is a simple one - 50kg centrally at the top tube with the bottom face the fixed bearing. Gives 0.12 mm lateral displacement. Now imagine two of...

Ah yes, bonding aluminium to avoid welding while getting the same rigidness.
You might enjoy a series on youtube:

Building Prototypes Dan Gelbart part 1 of 18 Introduction

I already moved...

Hm (naively asking) - if a crash like this happened, wouldn't the alignment and condition of the rails/carriages be questionable anyway?
If the bolts are able to 'give' a little it might just save...

OK, thanks for that info.
So if I get me some sort of long, very straight edge (bolt on) I can potentially omit the milled reference edges/pockets, which should make milling the flats...

Thanks for using the word pocket - made me think twice ;-)

A question in regards to this - the mounting reference for the rails - does it have to be one solid piece, or can this reference also be...

I would have asked earlier, but never had time to sit down and draw something up, as I couldn't find examples ;-)


Yeah, as short torsional lengths as possible, while the carriages as far apart...

@iwaskevin
Cool, thanks for posting. The y-direction bending/torsional stability of that gantry/portal would be worrisome to me in that design though.
I'd expect some struts and wire-strapping...

I think I've run across your current machine and it is of that design, a moving table fixed gantry mill.

Space wise you need longer y-rails and ball screws to move the part past your milling head...

Well, I was expecting that once pieces get heavier than 15-20 kgs I need to use a mobile crane anyway.
But anything smaller I should be able to put in the front there, doesn't matter for the mill...

I just got that from one of the threads here, where someone posted an image of a big one and they call it a portal milling machine - I mean I can find them via that with google.
I assumed that would...

What is the reason, that I don't seem to find a lot (actually none) designs/builds that try to scale down those large portal mills to shop format?
IMHO the design should be sturdier than a gantry...