I have wanted a CNC router for a while now, and I am ready to pull the trigger and buy one for myself for Christmas. The question is, which one should I buy or build?
Right now, my choice seems to be between Shapeoko 2 (on sale right now because Shapeoko 3 is coming soon), the OpenBuilds OX, or some other type/variant? It looks like many of them use belts, but this seems to be a problem with deflection because of belt stretching, so I’m wondering if a leadscrew design would be better, and if so, are there any open source designs (or kits) out there people here have experience with or would recommend?
Note that I want to be able to cut more than just wood–I’d like to be able to cut soft metals (aluminum, brass, copper), too.
@SirGeekALot Hi I’m pretty much in the same situation so feel your pain! Currently I’ve purchased a few components towards the Openbuilds OX though awaiting the release of the Pocket NC before I commit!
There are many different kinds of CNC machines because there are many different tasks people wish to accomplish. No one machine does it all well. Trying to mill metals with a gantry router machine is definitely not optimal in my opinion either. If you are really interested in doing that then I suggest you invest in a real milling machine. Because no machine made out of aluminum extrusions is going to ever compete with cast iron dovetails. Although if you slap heavy duty servos onto a mill it just might give a lot of gantry routers a run for their money. heh
@Paul_Frederick True, the more task-specific the machine, the better it will be. E.g., if I wanted to make only cylindrical objects, then I’d want a lathe.
I’m not looking to make really complex metal parts. I want it mostly for making parts that need to be stronger than my 3D printer’s plastic can handle. Metal parts of mostly flat stock is fine for a lot of things–I’ll just design around that.
Basically, all I want is light CNC for precise small metal parts, and maybe I’ll get fancy with wood. I don’t know. Right now, I just want to be able to make things in a manner similar to my 3D printer: design it on the computer, then have a machine make it for me.
@SirGeekALot Subtractive machining is not always nearly as cut, and dried, as 3D printing is. Trying to remove different amounts of material using different tooling from different workpieces adds innumerable variables into the equation. I’ll just let you discover all the joys of it on your own though I guess.
@SirGeekALot just to let you know, I cut Aluminum with my machine almost exclusively. Running TinyG on Chilipeppr. Granted I am not cutting crazy awesome 3D items into thick cast plate. I think you are following SMW3D and witnessed what I use this kit for. I do know it is a little limited, but does everything I ask it.
As a reference, I can cut a 1.76mm worth of material at 200mm/m through 6061 with a single flute up-cut. I can get a better chip with a two flute, but chatter gets a little crazy.
If you go towards the OX let me know, I can probably work something out for you.
@SirGeekALot
When you find the machine that works metal, and wood well you let me know. Then I’ll sell off my milling machine, and routers, and buy it. I could use the shop space.
@Paul_Frederick I’m sure it does not hold a candle to the tools in your shop, but the inventables website page for Shapeoko 2 states the following, “Open source kits to build a machine for milling plastics, woods, and metals”.
@SirGeekALot
Like I said earlier, you are going to have to learn some things on your own. For starters go learn what surface speed you are supposed to cut aluminum at. Then calculate what RPM you need to go to run at the right speed for say a quarter of an inch diameter bit. Then tell me why a router is not the ideal spindle for machining aluminum.
@Paul_Frederick did want to throw in you are correct on your above statement, about a 1/4" tool. I have loaded a few tools in this size and I can surface with the OX but cannot do any real milling at that size. I find with a spindle speed of about 12k and a 4mm tool it is great. Again though ageed with above, these are hobby grade and are not meant for manufacturing capacity.
I think they are a perfect fit for someone who enjoys 3D printing and small part manufacturing in their home.
@Brandon_Satterfield
Most routers are in the 20,000-30,000 RPM range. That would put the surface speed of a quarter inch diameter bit at about 2,000 Surface Feet Per Minute. Or close to 10 times the speed of what you should cut aluminum at. 12,000 RPM is better, but still puts the surface speed at about double what it should be. Now if you halve the diameter of the tool you are in the range. 4mm is about 5/32", so that is close. 4/32" is an eighth of an inch. 3/32" would be about the ideal size bit to use at 12,000 RPM to cut aluminum. That yields a surface speed of 294.5 feet per minute. Which splits the 250-350 surface speed range nicely.
@Paul_Frederick I actually have ordered several more bits, and for the reason you state. I know aluminum averages 250-350 dependent on grade, I tend to find with the OX we really have to err on the lower speed. To much speed and due to the very nature of this belt driven gantry, the bit will walk. So 200 gives a low chip load but keeps her from walking.
Clearly, I need to do a lot more research on this topic, or at least more clearly define my expectations of it and what I want it for. Thank you both for your input.