[garyocampo]

so yeah i was thinking that instead of using mdf for my cnc i could use polypropylene since it is a plastic it wont't be affected by humidity and it is pretty rigid. the machine at first will be used for cutting 2 mm thick aluminium wich i will then use to reinforce the structure, my plan is to be able to machine copper, aluminium, plastics and wood. this are the steppers i will be using for the machine i will also be using 16mm linear shafts and ballscrews, the intended machine lenght will be 60 Cm x 50 Cm.
sorry for the grammar and formating english is not my main language.

[CaptainVee]

Don't go there.

PP is not rigid, not dimensionally stable and temperature sensitive. It is a recipe for disaster.

Well, it may be possible to build a good router out of PP somehow, but it will take a huge effort and that could better be used for something else.

If you are worried by humidity, use mdf or better, HDF and epoxy to build a torsion box router, covering every bit of mdf with epoxy in the process.

[garyocampo]

And what do you think of the motores?

[CaptainVee]

Seems ok.

"using 16mm linear shafts" i'd go for 20 mm, but either way, make sure they are supported shafts!

Unsupported flex too much.

[victorofga]

just check on prices first..
acme screws already cost same, or even more sometime than ballscrews..

v-rollers, unsupported round rails also cost same than supported rails.. hiwin square rails you also can find in this price range and this would be the best..

for structural parts use steel square or rectangle tubes, for the lowest price..
don't sve a couple of dollar to not using aluminum for the sides..

shark cnc actually has some hdpe sides, and other parts, also it using acme scres, or simple threaded rods (?)
some folks likes it, some don't,,,
but no folks went to shark after they used any other rotuer..

for motors, just go with a kit where you get all parts and you can build it..

pending on where you located, in usa keeling inc
in Europe go to cnc drive
CNCdrive - motion controls

you also can check aliexpress, and ebay...