I’m currently splitting an STL mesh from a thingiverse in half so I can carve it (getting greater detail with the halves of each section than just a straight top-down carve of the whole model).
If the height of some of the mesh halves are between 40-50mm, am I going to run into problems with the tool holder not having a small enough radius to carve or contour by the time it gets towards the bottom of the models parts?
This will be my first 3D-ish carve with a roughing pass then a finishing pass. Should I just plan to order special/extra long bits? Any recommendations for what I might need if so?
A lot of it depends on how much detail you want. You can get longer bits, up to about 60mm. Which will give you around 45-50mm cutting depth. However, the narrowest long bits I’ve found are still 1/8 or 3.175mm.
The problem you get with long bits is deflection. By the time they’re that far out the bit and the SM end up with a lot of flex. So you can’t be too aggressive in speed or step-down.
I assume you’re using Fusion 360 for your toolpaths. I wouldn’t even try to use Luban for this. With Fusion you can have much more control over your rough clearing.
Lastly, the SM isn’t very powerful so you can’t cut very deep paths/grooves where a long portion of bit is making contact on two sides. If you’re clearing a wide area this isn’t a problem.
-S
Thank you for the considerations. I will definitely keep the passes shallow for the fine detail layer.
I have another question on optimal layout/carving. As you can see I have halved each of the sections of the model (red) so that more detail can be retained instead of a straight top-down (I haven’t done the guns yet, but everything else is set).
Should I try to carve all these in one go? Only pieces with a similar height? The gray base is 320x320mm. The tallest pieces (lower right) are approx 45mm. I feel all at once will involve a lot of unnecessary carving of waste material on the lower parts, but I’m not 100% sure how a model like this will carve. It’s also pretty difficult to get the pieces at the same height from the gray base I have now (the align feature has not worked for me).
Do I need to put each piece on its own base a little wider than the piece is? Do I need to have each piece in its own file (ie will the toolpaths try to carve around everything)? Any thoughts / recommendations are most appreciated!
Ok, that is a very complex model to be cutting up like that.
First of all, I would recommend not putting them all in one job. If something fails, you’ll lose a lot of work. So create a single job for every part. That way you can also use smaller pieces of material which will allow you to optimize the material used.
By the look of it, you’ll need at least milling from bottom and top and for some parts, from the left and right as well. (at least). Those are not the easiest projects to get started with.
A completely alternative way to do a project like this is to slice everything up in slices of 2mm thickness and carve those out and glue them all together.
And if you really plan on doing a lot of these type of cnc projects, the rotary module might be relevant as well.
If this is your first cnc project you’ll probably learn a lot but probably have a lot of valuable learning experiences as well (read, failed attempts and things going wrong )
Definitely do prototypes on cheap & soft materials (even like on styrofoam)
This thread has a lot of useful info for anyone starting with the cnc functionality.
As @brvdboss said you’re just asking for problems and more things to go wrong. It’s not bad to pair a couple similarly shaped and sized pieces. (everything else he said was on point too - very complicated, not sure how you’re going to do from just two, let alone one side)
If you make a rectangular block then when you move items you can see when they “break through” the sides/top/bottom of the block.
Not really a right answer to this. This is all dependent on which toolpaths you choose and how you set-up the toolpaths in Fusion. You can select where to carve and where not to. To simplify things I’ll sometimes save objects separately.
-S
Brvd, this won’t be my first CNC venture (I’ve carved two 12" wedding signs with 90 vbits and curved pockets with text on an infinity mirror) but it’s my first 2.5/3Dish venture.
The 2 mm sections is a great idea (though I’m internally grumbling about cutting them all ha). I was going to be content with the detail from just top-down carves but 2mm layers with the body first split at roughly the midline will probably work quite well.
At the moment this is a one-off pproject as I’ll be heading to Chicago’s C2E2 where two of the lead actors will be and want to make this for myself for them to autograph.
I plan to affix it to another piece of stock with the title of the show and ship name. I am still contemplating if I just want to work off half the model and affix it flush on this board or if I’m going to mount a more 3Dish version via some form of pins/rods.
SDJ, if I do make a rectangular block for the parts as they are, would I delete that before generating toolpaths to avoid issues?
If I end up just doing 2mm layers (which I think I am likely to), I think I can probably find stock to match that dimension (or cut my own) so it just cuts the contour of each sliver and any small slopes/details and I can avoid the height mess. But for future reference, if you were carving one of the pieces I have in the picture now, would you start with stock the same size and carve all the way through or would you leave a little below and deal with separating that after?
For 2mm slices, what types of toolpaths and bits would either of you use? I purchased the following two bits: Tapered Ball Nose and Massive Flat End Mill (these were in anticipation of needing a longer bit, though I’m quite happy to have them even if I change up the work flow to 2mm slices).
Would I use 2D trace toolpaths or stick to the 3D ones? Very open to your thoughts and experiences here!
as @sdj544 already said, I would also suggest ball nose for easiest use in this case. I’m not sure if tapered is an advantage here. (will increase cutting time unless you want to do a lot of toolchanges which will take a lot of time as well.
In the past there was also 123dmake from autodesk that would let you slice a model for you that you could than export for laser cutting or carving out. However that product is discontinued. You probably can still find downloads for it, but not sure how well it would still work. Maybe you can look at some alternatives.
However a quick search seems to indicate it’s still possible in Fusion360 as well: Solved: Re: layers of plywood - Autodesk Community
I’ve never used this before, so please let us know how it works out. Looking forward to see the result
I actually found a pretty easy workflow in the absence of a plugin. I made a 10x10mm square (arbitrary choice) and gave it 2mm height. I lowered the model to that height (then made sure the square was next to the model, not under it).
Then all I had to do was extrude the square 2 mm higher, use mesh plane cut to select the model then the top of the square/column as the plane and voila a 2 mm slice. Rinse and repeat. Using the “E” shortcut for extrude I never had to leave the mesh menu.
I’m thinking I may redo them as 3.175 just because its easier to find 1/8 stock (or I might try cutting my own with my yet unused bandsaw) and will result in fewer overall slices.
My next major consideration is whether I want to do them bottom to top in the horizonal or engine to tail (as if it were standing up).
I’m not thinking the ballnose will take too terribly long, even though quite small (and with the confidence of never using it yet ha), because only the edges of each slice will have any curves/angles. Which may make the smaller tail-nose slices better due to reduced travel distance?
Either way come the end of the next week I’ll either have success or abysmal failure as I would want this to be complete before Dec 10
You can use bodies or sketches to choose where you want toolpaths to go.
You can choose whether the tool path stays inside or is centered or can go outside what you’ve chosen
You can also increase the amount the tool path goes outside (or inside) of those selections by modifying the “initial offset”.
In my previous post with the boundary issue, setting no boundary did work but I’m encountering something that seems inexplicable to me.
First, these carves are of mesh slices so unless I were to add sketches or something, there are no boundaries to select for 3D pocket operations.
Even when I remove the boundary the carve still does the corners as illustrated in the above reply (it does carve out the part entirely, but I cringe everytime the next pass gets to a corner because it just plunges straight down there instead of any ramping profile I try). Carving the outside of these mesh slices of the model I can’t fathom why the toolpaths isn’t just one big circle starting as far out as it needs and spiraling in. I tried playing with different 3D milling options but they either errored out or didn’t do all I needed.
Twice on plunging cuts in the corners the bit jammed and stopped the spindle in the stock and movement on the linear arms (despite the machine still trying to move). I managed to stop the operation fairly quickly both times but I’m not keen on repeating this any time soon as I’ve tested my luck enough without obvious damage to the machine.
I’m using 1/4 stock and each slice is 5.9 mm, leaving a nice thin wood film as a giant raft/tab to prevent the piece from flying and smashing at the end. I was using a rather large flat end mill (6.35 mm / 1/4th) at the time but switched to a 3.175 mm out of caution.
Really I just want to stop the plunge cuts in the corners because nothing I can see setting wise is telling the machine to do those. These are not tall or complicated forms and I’m paranoid now each time with many more to go.
(I’d attach pics but I’m at work waiting on a program to decide to work).
I’m not super familiar with 3D toolpaths. Have you tried using 2D toolpaths like 2D pocket and selecting the features you want machined, including the stock? That might be a more straightforward way of getting the software to do what you want.
That thought did occur to me but there aren’t direct pocket to select because they are slices of a mesh model. I think I can convert it but I’ve heard that’s hit or miss?
If not for those corner cuts I’d use the bigger bit and halve the cut time for each slice .
3D Pocket should work fine. Sometimes adaptive gets a little weird because it doesn’t take into account the limited power of the SM. It’s calculating for the bit and assumes it can push harder than the spindle can actually handle.
Sometimes the easiest way to set boundaries is to create simple sketch of your object or portions of it.
It shouldn’t be suddenly plunging with 3d pocket. One of your settings must be wrong.
Share screen grabs again of your settings.
And if you want to share the fusion file too I can take a look. (might have to zip it to upload here)
This indeed. It must be a setting that isn’t appropriate. Sharing your fusion file is probably the easiest. (or at least the object you try to carve, I am curious, so willing to try and have a look at it)
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