New CNC Router

I have been fascinated with CNC for a long time. I have dreamed, schemed and designed all sorts of rail systems, drive mechanisms and electronic bits, but in the end, the closest I have gotten is a stalled conversion of my mill-drill. Much of the problem has been a clear lack of need that no amount of desire has been able to justify.

On the one hand I want a 5ft x 10ft table with a plasma cutter attachment, then I really want a high precision table-top capable of doing 5mil PCB traces, but, of course, I also want to be able to mill profiles in steel and cut gears out of exotic materials.....Twenty years of dreaming about the "perfect" CNC machine and I have finally made a decision! I am going with a table-top router based machine that can cut things the size of an A-4 sheet of paper with ~0.001" repeatability. It should do PCB's just fine, and perhaps some light aluminum cuts; it will work like a dream on wood/plastics. In the end it should get me started with CNC.

I can't think of any particular project that requires this new toy, but I am none-the-less very excited. The machine does not come with the router/steppers/electronics/software, so it will be a few weeks before I get everything setup, debugged and running. I will probably start with something mundane like a pattern in a block of wax, but hopefully before long I will be cutting small bits of stuff into parts and after that perhaps my first PCB! I will update this thread as I make progress.

Fish

[Gotwind Ben]

Great to hear you've finally made a decision Fish, after 20 years..
I may have the perfect starter project for you. I need to produce these in a reasonable qty (100), 6mm thick polycarbonate (Lexan) mounts. The one below was hand sawn and filed, and took me ages :x
N.B. I now use sintered bronze shaft bearings (not shown below).



http://www.gotwind.org/diy/12-inch-mini-turbine.htm

If it were very carefully setup, it may be possible to cut 24 mounts per A4 sheet.

LOL,

You want to turn my hobby into a job? Shame on you! LMAO. I don't know about the timing, but I would certainly think the router I have ordered could handle 1/4in Lexan. Of course, if you don't need them water clear, they could be cast with urethane resin quite easily, potentially a cheaper and faster route. Let me get it set up, and if you are still interested, we will take a look at it then :-)

Fish

[Gotwind Ben]

Hah.
It wasn't an instruction to go into to production :D , just an idea that might be a cool first time test piece.
Have you a link to the router, indexing table? you have ordered?
b.t.w
Unclear urethane resin casting is perfectly acceptable for what I have planned for those end mounts above.
The only accurate bit would be the 9mm central shaft hole (for a push fit of the sintered bronze bush).
I don't have much knowledge in this area, well none :D

[Gotwind Ben]

Also, the Instructables email newsletter has just dropped into my Inbox.
Thought this may be of interest to you Fish.
http://www.instructables.com/id/Mini-CN ... tructions/

Sorry for the slow response...I have been busy with Spring projects :oops:

Here's a link to pictures of my CNC router under construction....

http://www.cnczone.com/forums/diy-cnc_r ... ne-54.html

It arrived @ my house yesterday, and it is currently on my pool table in 10,000 pieces waiting for the paint to dry. When I get the painting finished I will post some pictures and post them. The stepper motors and controller won't be here until Monday, so I guess I will take my time with the paint job, LOL.

Fish

[Gotwind Ben]

Wow.
A very pro looking piece of hardeware Fish, nicely made by the looks.
Presumably (well obciously) it is a 2 axis machine. 3 axis would be great for some small air foil blade production. (I think) - Someone on Fieldlines did something similar from wood.

Thanks! Actually it is three axis, X-Y-Z (Left/Right, Front/Back, Up/Down) , but no fourth axis (typically a rotary index). For a prop you could do one side, then turn it over and do the other, but you would have to be very careful in your set-up/jigs.

Before I began painting I put it all together (finger tight). I was VERY impressed with how "tight" everything was even with the nuts only finger tight! The guy who built it is really very cool. He is retired and builds these as a hobby. The machine itself was $429. The steppers, controller, power supply, spindle mount, spindle (spindle is a fancy name for a router ;-) ), collets and tooling cost more than the machine by a good bit, lol. When all is said and done I will have spent ~$1500. (Of course if I decide to "buy" the software the total cost could skyrocket!, but no real plans to "purchase" any software for now :roll: ).

Anyway, I am building a PC while paint dries, LOL.

Fish

Ben,

As far as casting your parts, follow this link and read about some of the mold materials:

http://www.smooth-on.com/

They have videos & how-to's that should get you up to speed pretty quickly. I am sure there are similar products available in the UK. Alumilite is a urethane I have used in the past, and it is good stuff. Check out their web page here:

http://www.alumilite.com/

The only real tool you might need that you won't likely have laying around your shop is a vacuum pump and a vacuum chamber for degassing the mold material. For relatively small bits like you will be making, you can build a vacuum chamber fairly simply out of a "glass cake cover", a piece of flat metal (I have never tried it, but I have thought a plastic cutting board might also make a good base), a hose barb and some of the silicone mold material (to make a gasket). You simply drill a hole in the metal and tap it for the hose barb; then you mix some silicone and pour a "ring" the size of the cake cover. Let the silicone cure and you have a "vacuum chamber". It is best to use the vacuum chamber to degas a second batch of silicone and make a new seal that does not have "air pockets". From there you are ready to degas your silicone for making high quality molds. A vacuum pump can be purchased or built. I built mine using a "piston type" AC compressor from a car and a 1hp motor.

As far as tolerances go, the finished part will be EXACTLY like the original. Every tool mark, scratch, blemish, flaw etc will be captured precisely. The alumilite I have used has ~2min working time and parts can be cycled about every 5min. It will take a day, maybe two to make your mold(s). After that, you can make parts very quickly. With 5 molds you could likely turn out 60 pieces an hour w/o much effort.

I would suggest when you make your molds that you cast the bearing into the part. To do this you simply make the mold from a part with the bearing already installed. When making the part, you simply install the bearing into the mold as an "insert" and then cast the part. When the part comes out, the bearing is already mounted. You can actually even "cast" screw threads, but it is better to use a nut as an insert or simply use a smaller diameter smooth shaft and then tap the finished part (the screw threads in the mold do not last very many part cycles before a new mold has to be made).

Using "dowel pins" and structural pieces to support the mold material can significantly improve mold life and accuracy. For instance using a wood or metal base with a dowel pin the same diameter as your bearing ID as the "center" for your mold ensures alignment and fit. Same for your bolt holes, using dowel pins pressed into a wood or metal base will increase mold accuracy and durability. But for 1/4in thick parts, I would think a single dowel pin for the bearing would be sufficient support for the entire mold, or, if the bearing is longer than the part is wide, you could simply have the bearing "fit into" a hole in either the silicone or through the silicone into a wood/metal backing plate.

Anyway, if you really want to go into any sort of production on these parts, casting them is by far the best answer. If you will CAD the part up and send it to me I will make a copy or two on my CNC router (or on my manual mill, lol) then if you feel overwhelmed by the mold making process, I can make you some molds and send them to you, lol. Once you have the molds you could train a monkey to cast the parts. (Hehe, I might even try cutting the mold directly out of plastic on my CNC router; that might be fun;-) )

BTW, UPS updated the delivery of my steppers and controller to Today :-) ; so I might actually get the bulk of the assembly done this weekend! I need one more coat of paint....

Fish

[Gotwind Ben]

Fish.
That's great info, and always appreciated.
Please let me digest it, late here ;)