>I am in the process of making a cnc pcb engraver and it seems like
>the hard part is the designing. I was thinking of offering a kit or
>the whole thing for sale or auction. What I am building will also
>be capable of machining wood and plastic up to like an inch thick
>(hopefully). This would allow you to make custom stamps from bitmap
>images (great christmas gifts for women and kids). I would not sell
>software with it, as I have found several free programs for doing
>what I would like to do. I might include a cd with the free
>software on it but would need permission from the programmers
>first. The engraver would be capable of working with like 14" by
>14". This may be premature, as I am still in the design stage,
>But... My question is, what would be a reasonable price to pay for
>such a thing? If it is not worth doing I don't want to make it
>easilly reproduced. What do you think? Would it be worth doing?
>Thanks for any input!
>
>Ben Englund
Hi Ben
There are many such machines already available in the market as Stefan
pointed out. Search google for "CNC milling machine" or in german "CNC
fr∗" and you will get an impressive list of options. Many of them are
made by people which had the same intention as you. Create a good
machine for a low price. Interestingly, if you want a machine that is
precise enough to drill PCB's (even more for PCB milling) and which
you can use to engrave front pannels etc. they soon find themselves
offering machines which are all about at the same price range!
I also agree with Stefan that for creating PCB's the wet way is
better, but I know that there are people who think different about
this.
Anyways, a CNC milling maching comes in handy if you need to drill the
holes in the PCB and for engraving all kind of other stuff, but
milling PCB's results in some serious limitations and is not even
really faster in the end. I'm in the market myself for such a machine
(to drill holes) and I also consider building one of my own for the
fun of it. I haven't made up my mind on this yet. There are MANY sites
descibing how to build one and also many sites which offer such
machines either finished or as a kit. A machine of the size you
describe usually goes for ~$2500 if it's worth buying it and if you
build one yourself you can save about half the price at the cost of
one to two man months of work provided you have only a few minor
errors in your design. There ARE machines out there which are cheaper,
but these are also those machines you find most complaints from their
disapointed users in all kind of forums related to the topic. If you
start to develop a machine from scratch, you soon will find out that
you must rebuild some parts of it cause the first idea did not worked
good enough etc. I actually experienced a simmilar thing with my
through hole plating machine. That said those which will build one
based on my machine will save a significant amont of money and time
just because they can avoid errors that otherwise definately WILL
creep into your design. Such errors tend to be expensive with regard
to time and money :-). Of course, if you are alredy very experineced
with this kind of work things are different, but I figure if you were
you most likely would not have posted this question. :-)
The task can be broken down into three major steps. The mechanics with
the stepper motors et all, the controller electronics needed and the
software. The last part can be left out cause there are good comercial
and also free packages around - I agree here with you. Controller
electronics can be bought also, but I figure most people reading this
e-mail list would be in the position to create one on their own if the
need would arrise. This is also the area where I think it's easy to
save some bucks.
All in all, unless you intend to do this as your hobby - or then have
the marketing power to put some $200k into building up a company that
market and sell such machines worldwide I would not consider going
this route. That's however only my 2ยข of course.
Markus