Hey there. I’ve just purchased the Pro, for delivery whenever. I’m totally new to this technology, but have no doubt I can figure it out. A question…Assume I’m cutting a circle out of 1/2" walnut, with a shallow well in the centre. How much finishing can I expect to do? Will it look really rough when the unit is done with it? I don’t care about speed, so I can use whatever settings will get me the smoothest. Then my question becomes - what is best to do quick finishing with? I make miniature silver sculpture, so I have electric finishing tools…I’ve just never had to finish wood. I have no desire to hand sand. Same question if I cut a circle out of acrylic. Will the edges be rough?
A CNC machine like the Nomad is accurate and precise to 0.001" (one thousandth of an inch). The machine far exceeds what conventional wood working expects.
When one machines, the most common approach is to rough (cut away quickly) most of the material that needs to be removed. The roughing will leave a little bit of material to cover the shape that one wants when the works is done.
The depth of the layer left after the roughing is set to ensure that the fast cutting never damages (touches/tears/gouges) the surface of the ideal object embedded within. We’re talking 0.010" or less.
One then finishes - go slowly, careful, and with great concern about the finish - the object, removing the small amount of material that the roughing left. Obtaining the finest finish doesn’t necessarily mean going really slow… just (much) slower than roughing. With care - often by performing some experiments (what we call feeds and speeds tests) - the finish will be pretty darned good for a nice block of hardwood.
Any tool marks - “ripples” left in the wood that cause the desired surface to depart from the perfect - will be very small indeed. If any sanding is necessary - and that will vary with the wood, the geometry of the part, and the machining choices - it will only require a very minor sanding (a very fine grit) because the machine has done it’s work to levels much smaller than conventional wood working is capable of.
I did a Steampunk case for the modulator (controller) for a Tesla coil in Red Oak last year. When the cutting was done I could just barely perceive a few tool marks. Less than 5 minutes with 180 grit sand paper and all of the wood was like glass.
Acrylic - I prefer polycarbonate but YMMV - can be machined to near utter perfection in the two passes however to do so will entail the use of tools (end mills) specialized for these materials. I’m talking near glass like finish. A good job can be done with conventional end mills but that amazing finish is bet obtained by using the right tool for the job.
Since you’re new to this, use the forum to ask questions. Be sure to work through the initiates exercises and read up on CNC.
@mbellon, thank you SO much! That was the info I was after. The main thing with any new purchase is whether it is actually capable of doing what you want, after you learn how to use it. All of the talent in the world can’t help you if a machine isn’t capable. From what you’re saying, this machine is.
Thanks also for explaining the roughing procedure, then the finer finishing passes. I wasn’t aware that that was how things work, but it makes perfect sense.
Still wondering if another wood person might pipe up with what fine finish attachment I might use on a machine like my Foredom mini lathe. I’d rather spend 15 seconds with that than 5 minutes by hand, and I’ve got wrist issues, so it’s nice.
When I need to sand - which isn’t very often - I use a small orbital sander. I understand your wrist issue… but cannot comment on alternatives for your mini lathe.
You should definitely take your time and conduct some experiments. We can help with how to do that. Pieces of scrap make perfect laboratories for tests. You shouldn’t be surprised that the finish on wood can be very, very good, even without sanding.
The CNC wood workers I know sand - from time to time - to obtain mirror finish.
I do a lot of woodworking on the nomad - hardwood baby teethers and rattles - and the finish sanding required is minimal.
This may make me sound naive, but I picked up a black and decker mouse sander and it makes smoothing out my parts quick and easy. There are a number of attachments that would make sanding a majority of a bowl really easy
