Could someone look at this design?

[candle]

Hi, since it is my first post I would like to introduce myself
My name is Sebastian Bartkowicz, and since i had never anything to do with mechanical design (well.. till last month) i'm pretty new for cnc at generall
Anyway, since I mostly build electronic equipment i wanted machine for fast prototyping pcb - if i could mill some parts in aluminium alloys - great
some data:

working field:
300x334x67mm

construction:
aluminium alloy PA11 (5754 alloy)
MDF for table core and X (Y?) axis support

linear system:
inductive hardened seel rods 12mm diameter
LM12AJ linear bearing
acme M6 threaded rod with 30mm long nuts
NEMA 23 size 1.2Nm (1.89Nm) steppers for all of three axis

spindle - initially dremel 395, since i already own it, in near future makita edge mill - similiar in size to kress, but at least avial around here

edrawing of my design
bare edrawings file
all aluminium parts will be cut by waterjet - limited accuracy, true, but i don't know any cheaper method of doing it

[mxtras]

You might have better response if you post a DXF. Just a suggestion.

Scott

[candle]

dxf as you wish - sorry for awkward positions - can't really do it under solidworks
dxf

then again - why would one want to watch flat model, if he could 3d one?

[smarbaga]

its like everything else, your machine is only going to be as good as its weakest link.
if you want to mill pcb's take a look at MrBeans job on here.
the size you have chosen is perfect. i think a lot of people ( myself included ) start out close to the size they really need, then they get dreaming and shoot for a 3 m X 3m unit, that they can never finish or with an area that they will never use and no place to put it .... etc ...etc.
if you check the e_bay thing you can get complete movements ( ball screws etc sometimes for around $30-60
then design the rest of your machine around what u aquire. one axis at a time.
this way your axis will be accurate, smooth and you don't need a machine shop thats set up for rocket engines ( a bank in your pocket too)to get a good result.
this is just one of many avenue.

[candle]

i won't find what i need on polish ebay, and prices on ballscrews around here are bigger than my budget for whole machine
i would really appreciate comments on actual design rather than suggesting that i should start with ballscrews, thk linear sliders and so fort from start
is not that i cant stand criticism, just would like constructive one
i don't want anyone to feel offended by my writings, so please don't take any

[mxtras]

I think your design is reasonable for it's size and apparent, intended use. You have good bearing spread for stability and it appears to be a very simple construction - nice!

Scott

[candle]

mxtras, how you find vertical section being 18mm thick mdf board? i suppose i could use 12mm board, and sadwitch it between two 3mm thick sheets of PA11 should more rigid, wonder how it will increase costs of this construction
i'm still waiting for RFQ answer from local waterjet company

[mxtras]

I think that 18mm would be ok - you could always add a stiffening rib or two if you had too much flex. Or you could use 12mm and add a few stiffeners - might be lighter AND stiffer than the 18mm.

Scott

[candle]

got the rfq from my local waterjet company - ain'tt going to be chep - for metal parts $400 - not that much, but not like i have that much in my pockets right now
need to wait at least till monday anyway
one way or the other i'll go for it - electronic part will be piece of cake for me so no other costs as for basic components here
i wonder if i should get into microstepping or not - this will be microprocessor based anyway, so i'm limited only by my imagination (and board size )

[candle]

mkay, 2 axes cut, and being assembled


will keep you inform

[project5k]

thats some spiffy metal work there, but may i suggest using the thumbnail feature... its a little easier on the eyes

[candle]

suggestion appreciated, now... where were we..