I want to have a CNC mill to make PCBs on.

Requirements:
Working area: 160x100mm, 320x200mm would be nice but is not needed.
Precision: Precise enough for SMD.

Price:
Max 250 EUR + shipping.

I have access to professional CNC mills and lathes for metal work for the next couple of months, so I'm wondering if I should buy one or make one myself using a dremmel or similar.

I've been doing a bit of math and it looks like I'll be spending about 50% of my max. amount on motors and I'm guessing about 25% on a dremmel(not sure what they actually cost here in Denmark) and that leaves not a lot for the mechanical parts.

If I build myself I will use EMC2 from linuxcnc.org as a controller.

If I buy I'm fine with a good condition second-hand machine too.

if you go the purchase way IMHO 250euros is not enough to purchase 3 decent steppers motors + stepper drives + metal/bolts/etc

Start by making a list of the items you will need and check again your numbers, also, if after a couple of months you don't have access to cnc machinery you may end up stalled in your build.

Do you have the DIY design ready?


Lots to think :)

Do you have the DIY design ready?

Not entirely. I have a work in progress:

http://www.instructables.com/files/orig/F9Y/LES0/FV15TUHR/F9YLES0FV15TUHR.jpg

but it'll be redesigned some if I build my own, it will be a gantry design though.

If I settle on a final design soon it shouldn't have a problem getting the metal parts done in time.

Looks like an optical illusion..... €250... Kinda tempted to sell you my new router....Shucks I managed to resist....

finish your design, make an item list, cost them, then you will know :)

finish your design, make an item list, cost them, then you will know :)

Motors:
http://dk.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMu0WtFXTgs3LvbD76Eq%252bivA6nMhcaFYPOw%3d
Quantity: 3
Total price: 138.15 EUR

Dremel:
Quantity: 1
Total price: ? Can't find a local price anywhere, assuming 66.66 EUR(500 DKK)

Metal parts:
Quantity: 1 set
Price: ? depends on final design and choice of metal type.


So it's about the same amount, the better question is if I'll get a better mill for the money by buying or building. What can I expect of the average new or second-hand mill in this price range?

budget is at least 3 times 250 for DIY a good machine.
If you buy one think even more

Motors:
http://dk.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMu0WtFXTgs3LvbD76Eq%252bivA6nMhcaFYPOw%3d (http://dk.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMu0WtFXTgs3LvbD76Eq%252bivA6nMhcaFYPOw%3d)
Quantity: 3
Total price: 138.15 EUR

Dremel:
Quantity: 1
Total price: ? Can't find a local price anywhere, assuming 66.66 EUR(500 DKK)

Metal parts:
Quantity: 1 set
Price: ? depends on final design and choice of metal type.


So it's about the same amount, the better question is if I'll get a better mill for the money by buying or building. What can I expect of the average new or second-hand mill in this price range?

You don't have the drives for the motors listed nor switches, wiring, power supply, bearings, or rails.

You can't just throw together junk and expect to accurately cut PCBs. Accuracy requires design and planning. Basically, you want as close to no flex and no backlash in your design as possible. I have cut PCBs with my router which was built with Thomson linear rails and bearings and I can successfully cut thru-hole stuff if I allow 0.020" traces but there is no way the current design will cut SMD stuff.

Alan

IMHO these motors are weak, go at least nema23

IMHO these motors are weak, go at least nema23

Ouch, if I need to do that I'll overshoot my budget by 150 EUR just by buying the motors. http://sine.ni.com/nips/cds/view/p/lang/en/nid/203937

that motors are to expensive,

the 23Y are 36 dollar a piece

http://www.anaheimautomation.com/products/stepper/stepper-motors.php?vTID=75

that motors are to expensive,

the 23Y are 36 dollar a piece

http://www.anaheimautomation.com/products/stepper/stepper-motors.php?vTID=75

Aah, that's a lot more affordable.


Motors: 77 EUR
Dremel or similar: Assuming 70 EUR
Electronics: Assuming 50 EUR
Metal parts: ? EUR
Screws and such: ? EUR
Controller: 0 EUR, already got a spare PC that will run EMC2
-----------------------------
Total: 197 EUR + metal parts and screws and stuff.