Hello,
looking to build first cnc and wondering what are average times needed for carving low poly shapes on wood .
It’s pretty hard to estimate. The total length of cutting is what generally determines the speed. So if you cut out the outline of a part, even a big one, it won’t take long. If you pocket out the same hole, it can take a long time. If you’re talking about 3D shapes, then the bit needs to travel across the entire surface, with a big step over, so the time will end up huge with a big work piece.
The complexity of the shape generally doesn’t determine the speed. Cutting out a circle is the same as a square with the same perimeter length. It’s only when you start lifting the bit all the time that the shape matters.
You’ll also end up getting better with time. When you start, the settings are pretty conservative, to save on frustration but there is lots of room for speed ups in the end. When you get the machine dialed in, you can cut deeper, and then just cut the finishing cut slower.
If you want better estimates, EstlCAM can give you an estimate in the preview window. I’ve seen it being about 20% short, just because EstlCAM doesn’t know about the machine limits.
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I would imagine axis motors type (NEMA 17 / 23 / …) as well as spindle speed being crucial factors
We are limited by rigidity at this point , not really the spindle power or steppers. It is a balanced system. Smaller frame, more rigid, faster cutting. I don;t think this was really the question here though, more of a ball park cut time question I think.
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This took about a half hour. It’s about 2 feet wide by about 18 inches tall. Depth of cut is about an eighth inch. Cut with an eighth inch flat end mill.
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This little guy took about 20 minutes to carve out. He’s about an inch and a half wide by about two inches tall, by a half inch thick. Cut with a sixteenth flat, finished with a sixteenth ball end mill.
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This took about 20 hours to cut. The image is a little under four feet wide by about three feet high. Cut with a 60deg v-bit. Depth of cut varies.
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“How long” will vary between machines as well. Like Ryan said, we’re limited by machine rigidity. The image in the middle was done on my MPCNC when it was expanded out to do full width sheets of plywood, so I couldn’t go as fast as it can now that it’s back to around 2 feet square. I’ve not tried something like that on the lowrider yet, so in theory I can cut faster, but with something like that, you really don’t want to screw up in the middle, that’s a lot of wasted time and materials.
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@Barry, that’s a very helpful way of explaining it.
Figured examples would work better. I usually don’t keep track of cut times. I know what repetier says is usually horribly wrong though.
Next question would be how much does mpcnc working time costs …
As in your time… Or like electricity? There is little to no maintenance, other than replacing bits, and electricity, the dewalt is 600w the electronics like 3w.
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No others factors affecting costs come to mind .
Maybe risks related costs , as per firing accidents ?
A guy did mention his previous cnc , not mpcnc taking fire (he mentions the the z axis) , that could be pricey …
I’m not really sure what you are asking, or why really. Maybe a little more info and we can help answer your question. What you are asking is so broad we are all just kinda guessing at an answer.
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As for the fire, never leave a active spindle unattended.
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I am interested in setting up a wood toy production business , nothing fancy , but must consider competition.
I’ve seen cnc made wood toys on amazon.com at quite low prices , not sure I can compete with asian manufacturer on costs (I am italian) .
So I am trying to figure out how to glue a passion and a buisness and make some money .
I’m not sure I’d use the mpcnc in production. You’d be competing with much larger, much heavier cncs, which are much faster. This is more of a hobby cnc.
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A better way to use the machine would be to cut templates, jigs, fixtures with it to ease the use of larger hand tools. Router bits with a guide bearing and template are among the fastest ways to cut things. All depends on what you are making though. A cnc for production is not usually the way it would be done though without spending a ton of money on the cnc.
I think building a small LowRider would be a much better option, it only cost a little more but at smaller sizes can really rip through material. A LowRider at full 4’x8’ size is about the same speed as a 2.5’x2.5’ MPCNC, but a 2’x4’ LowRider (4’being the table axis) would be much much faster. For the type of stuff I typically do on my CNC I use the LowRider way more often.
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I also wouldn’t really try to compete with the import stuff. Do it better and sell to a different market. The easiest way would be to use better wood or something. There labor costs over there are nothing and really can’t be competed with.
There are people that are willing to pay a more for quality, and there will always be the people that are going to buy the cheapest thing no matter what, they are not the customers you want to chase. I sell what I consider to be one of the least expensive CNC’s on the market and there are still a majority of the users that spent a lot of time buying from many sources to save a little bit of money and still try and cut corners buy not spending a few more pennies on sealed bearings and/or spending hours hand wiring instead of the wiring kit. I love them to death but my time is worth more than that.
I would make them and hand number them and sign them or something to differentiate yourself. Made of sustainably harvested wood or “reclaimed wood”, Bespoke=$$$$.
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This is how I would overcome the above mentioned problems.
Adopting a stiffer frame with corners span supports thicker steel tubings, Nema 23 and a stronger spindle .
A good image recognition software for video monitoring cnc activity to avoid attending it all the time .
Simple basic wood shapes for a very large bit , no details.
This being wood toys available on amazon :
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Yikes. These all come up a lot. And I am really not going to do this again they are all answered in the FAQ’s
Adding different parts makes a different machine, This machine is balanced very well with rigidity and power, changing any one component will do nothing for it. Build a whole new machine, sure it could be faster, but it would cost much much more.
Never ever use a power tool remotely, you need to be within arms length at all times. High an intern if you have more important things to do. Or better yet sub out your jobs.
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If you think it would be fun, and you want to tinker, then I think you should build an MPCNC or a Low Rider. If you have no CNC experience, then start with the model unmodified, and build confidence and understanding. I don’t think any of those changes will significantly change the cost equation and you won’t recover your investment. The “base” machine in either MPCNC or LowRider is at a great inflection point. You can learn a ton, make some things, and develop a huge capability set by having this machine as is. It takes a lot more money and a lot more effort (think US$ 5000) to get something that is significantly better.
My thoughts on running a business with a CNC are:
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The MPCNC size/style/cost is best for nearly completely custom items. Things like engraving someone’s name on a sign or a cutting board. You could bring some example cutting boards to a craft fair, and take orders all day. People will pay 2-3x for something that is made responsibly, in the local country, by someone they’ve met. When designing these things, try to make the CAD/CAM as easy as possible, by only changing the text, but choosing from a few predesigned shapes.
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CNC machines, in general, take the same amount of time cutting straight lines as curves, so you get more bang/buck cutting something that requires precision, but isn’t square. The plane above is a good example. You can cut those with a scroll saw pretty fast, but it’s labor intensive. You’ll cut the time down a lot of you do the router/pattern bit and cut a template with the CNC, but it will still take a good chunk of your time.
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Another place that CNC machines crush it vs. normal power tools is locating holes. Drilling a hole is really easy with a drill press (as long as the drill press can reach), but it’s very time consuming to get the holes in the right place. There isn’t a good tool, like a table saw, for drilling holes quickly and accurately. Making 27 holes in a piece of wood, in precisely the right place would take a few minutes on a CNC and a few hours with normal tools.
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Remember to compute your time in CAD/CAM in addition to the time machining. Eventually, you could combine tasks and have your CAD/CAM working in parallel to the machining. Don’t go crazy getting 30 orders before you try doing it a few times. Having 1-3 outstanding orders at a time will let you get a good sense if your pricing estimates are close to right.
In that specific example, trying to compete with the imports on amazon is going to drive you crazy. Better shoot for the crafty, locally made type of markets. Adding some customization, like allowing people to add “Happy 6th Birthday, Sam” to the bottom, will give you an edge over the amazon stuff. Making it from responsibly harvested pine, and hand finished in Italy will add a lot of value too. You’ll need to charge 2-3x the material cost to make any kind of profit, due to the stuff that will break, and the time you’ll spend, and the waste. If those planes are coming from China, they are going to be making 5% or less on each one, and selling them by the 10,000. You might even find a market selling the pieces to the US market, in stores like etsy (or what etsy used to be). I would pay more for something made in Italy, with a custom engraving on the bottom, and finished by hand (and I mean, like $100. I wouldn’t pay more than $20 for it at ikea).
And forget about leaving the machine alone. You could be doing something else while it’s running, or babysit 5 machines at once, but you can’t go do your shopping or start it then sleep while it’s running. When things go bad, they get worse quickly, you’ve got a minute or two at the most before things end up in disaster.
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Here’s an example of the easy stuff you can do.
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