Hi folks

[Wirehead]

Hi, I've just joined, My name is Greg and I live in Sydney.
I use a CNC hotwire cutter at work so i do know a little about them.

I'm looking for either of two things:
1. Someone local with a hobby/smallish CNC who could help me make parts for projects, or

2. Someone who can sell me parts or possibly a finished small CNC so that I could make parts myself (preferable). The finished parts I want to make are not heavy duty, mostly plastic, wood and aluminium, 45cm on a side or less.

I've seen some great homemade CNCs on the net but they seem to require some accurate machining to put together which is kind of a horses/carts problem for me.

Can anyone out there help?

[rocket67]

Greg, If you are prepared to buy a new machine check out the Excitech range from sh-cnc in China.
There is a thread in the Commercial Wood Router section that deals with these machines.

Rocket.

[Wirehead]

Thanks, Rocket!
I checked out the Exitech site and the machines look okay, but I have a new question: These machines (and i mean the smaller ones, SGH404 and SHM609) have a repeatability of .02 mm - sounds good but . . . . is that good enough to make working machinery with, and would this sort of machine cut steel okay or would I need to shell out bigtime for that?

Incidentally, are there other Exitech users out there who will give me some feedback on quality and price? I can't see any prices on the company site so maybe I need to buy from a local agent . . . ?

[Rodm1954]

Greg you seem to have changed your mind from light stuff to steel in one post. Don't worry we all go through this type of thing while we are in the planning stage.
The Excitech is a good suggestion given your first post and yes 0.02 is quite reasonable. That is 0.00078 of an inch (less than one thou) so a lot better than any of us can do by hand.
For steel you need a CNC mill.

[Wirehead]

Greg you seem to have changed your mind from light stuff to steel in one post. Don't worry we all go through this type of thing while we are in the planning stage.
The Excitech is a good suggestion given your first post and yes 0.02 is quite reasonable. That is 0.00078 of an inch (less than one thou) so a lot better than any of us can do by hand.
For steel you need a CNC mill.

Thanks Rod, great answer -
Should I assume that a CNC Mill would cost more for the same working area?
How about plain old mild steel or sheet? Can't I just slow the feedrate down with a nice, sharp tooltip?
What's the big issue here?

[Rodm1954]

Any type of steel is tough so there is no give in it, it builds up heat at the cutter and does not absorb vibrations like timber, acrylic and even aluminum. You need slow speed spindle compared to a router, preferably coolant and a very rigid machine so the cutters stays on course and does not heat up too much. If the steel heats up it damages the cutter and can harden the steel through the temperature change - stainless typically work hardens.
I am being general here and not being an expert this is my take on what happens so probably the best way to answer this is you would never cut steel with a hand held router so the same applies with a CNC router.

Yes a mill is more expensive and unfortunately is not really suitable for cutting your other materials except aluminum which sits in the middle of both machines.

Hope that helps and I am not an expert so if anyone can offer a better response then please do so.

[Wirehead]

Hey thanks again, Rod, that's a good clear reply. I'll be looking at Mills from here on in.
I'm sure a Mill could be used or modified to work softer stuff but not vice versa.