First aluminium cnc build

[Jur1]

Hi all,

I am planing to build me my second cnc machine from Aluminium. The first cnc was made out of mdf. Sadly because of move to another country I did not have any time to make parts with my old cnc for the second cnc.

Anyways before I starts I have couple questions. First of all what do you think from the design(picture 1). Some of the detail work is still not finished, but good enough to start building. The base frame is made from 45mmx90mm 8020 aluminium and rest of machine is made out of 15x30 8020 extrusions and extruded aluminium plates. Should I add more thickness somewhere? My plan is to use this machine mainly for wood and plastic.

Working area for this machine is around:
x 800mm 31"
y 600mm 24"
z 90mm 3 to 4"

My second worry is that the aluminium plates has to much tolerance for the build. Each aluminium plate has a tolerance of 0.008" in thickness.The problem is showed in attached picture 2.

-Juri

[Boomslang]

Move the Y rails to the back of the uprights, bringing the Z axis more in line with the X bearings.

[Jur1]

Move the Y rails to the back of the uprights, bringing the Z axis more in line with the X bearings.

It was in the first place as you say, but to simplify the build I moved it as it is now.

Any comments on the aluminium plate thickness do you guess think it is enough? I am eager to order more parts...

[Jur1]

ordered today all the aluplate parts from www.onlinemetals.com. Total cost including shipping 100$. I hope that the aluplates are strong enoght. Anyway I am hopefully that it will work and that I can start building next week.

Attached the order and ordered parts status in red.

[RomanLini]

My experience with larger aluminium plate (ie 1/4" and thicker) is that the thickness is very reliable, at least with pieces from the same sheet of metal.

I've never seen anything like 0.008" variation in thickness in a single piece of metal. Although I should say I normally buy good quality sheet in 6061, from a reputable manufacturer.

[Jur1]

Aluminium arrived !

RomanLini as you said the 1/4" plate is very stable and does not bend easily and there seems not to be the variation what is was afraid of.

I started drilling the Y axis. The rails are attached by 5mm bolts and I dilled the aluminium by 7/32" drill to get 0.5mm adjustment. If you take account that the rail has an 6mm hole I am sure that I have enough gap to handle the tolerances.

I was surprised how easy the aluminum is to work with I was thinking it would be much harder. Attached some pictures of the progress. Hope to finish tomorrow rest of the Y axis and move to the Z.

[cliffy]

Looks like you don’t have much respect for good furniture.

[neurofen]

so long as he doesnt drag it along the top of the wood it should be ok :

[oldvan]

A layer of cardboard would save the finish.

[Jur1]

I hate that table and general quality of that table is horrible! So this will be its last use.

[Jur1]

Finished today the y-slide. I noticed that I need more accurate when I start to build the Z.The IKo 9mm has more and smaller holes. I had some difficulties to fit the Y-slides to the aluminium plate. How accurate results can I get when I print the hole layout to paper and drill the holes based on that?

You can find attached pictures from today.

[Jur1]

Bolts ordered