Complex 3D carving / sculpting

[JulianDR]

Hi everyone!

Is there anyone here doing serious 3D carvings with a CNC wood router? I'm new to CNC and I haven't got my machine yet. Still, I'm trying to figure out what is and what is not possible to do with a regular CNC router.

A few questions for those in the subject:

Is it possible to make undercuts? I mean, can you create an overhang by removing material at an angle different to the perpendicular to the plane? How do you do it? Do you use spindle aggregates to modify the angle of the bit?

[Frantic Fab]

Julian,

Hello, my name is Garrett. I work for a company called Masterpiece Models i am a fabricator/CNC machinist. we have a 4'x8'x8'' cnc router and are currently looking for ways to keep it busy! i happen to be extremely efficent in 3d solids manipulation programs such as solidworks, inventor, rhino ect. If you are looking for someone to produce this for you we can do quickly accurately and best of all cheaper than most!
for your question about undercuts there are a number of specialty bits that can accomplish this with respect to details. another option i have used a few times is to make a jig to hold specifically and securely the part to allow you to flip the part 180 degrees and continue machining the back side. this allows a 3 axis machine to operate closer to the realm of 4 to 5 axis capabilities. however time consuming, this can be a solution if you do not have access to a more advanced machine. Please look at our website to see what we are capable of. Masterpiece Models if you have any questions please email me at jolleygreeengiant@hotmail.com i would love to help you out!

Thanks,
Garrett

[awerby]

Hi everyone!

Is there anyone here doing serious 3D carvings with a CNC wood router? I'm new to CNC and I haven't got my machine yet. Still, I'm trying to figure out what is and what is not possible to do with a regular CNC router.


A few questions for those in the subject:

Is it possible to make undercuts? I mean, can you create an overhang by removing material at an angle different to the perpendicular to the plane? How do you do it? Do you use spindle aggregates to modify the angle of the bit?

[I'm not sure what you mean by "spindle aggregates, but the short answer is "no". However, there's plenty of carving you can do without needing undercuts, and it's not against the rules to go in afterwards and put some in by hand if you need them.

You can also make a fixture that would act like a rotary fourth axis on which you can mount your workpiece, and then manually revolve it to an indexing point, say 10 degrees off perpendicular, and run another toolpath that's calculated on a rotated part.]

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[JulianDR]

Thank you for your input!

for your question about undercuts there are a number of specialty bits that can accomplish this with respect to details. another option i have used a few times is to make a jig to hold specifically and securely the part to allow you to flip the part 180 degrees and continue machining the back side

Can you give me a few details on the types of bits you use for elaborated carvings? It'd be great to know which bits you use for what...

It's interesting what you do with the jig to flip parts... In my case, I will be working mostly with big panels, but I'll take it into account when I get to work on smaller pieces...

Quite impressive what you guys do... thanks for offering your services...

I'm not sure what you mean by "spindle aggregates, but the short answer is "no"

By aggregates I mean these type of heads you can adapt to a spindle in order to be able to use a tool on a different angle: Aggregate for electrospindles, HSK Aggregate, ISO Aggregate - HSD (see the different types, for drilling, milling, cutting, floating and so on)...

What I understood when reading the brief description of these aggregates is that you can get to use your regular 3 axis CNC router to make cuts or carve at an angle different from the default. Of course, it is not dynamically controllable (AFAIK)... you fix the head at the desired angle... I still don't know if you can make your CAM software aware of the different angle or if you have to make calculations manually. A simple practical example would be if you needed to drill a hole at a 45 degrees angle... AFAIK, you can't do this with a 3 axis machine and a regular spindle pointing down. It seems possible with one of these aggregates.

[ger21]

Typically, those aggregates are used on big industrial routers to do very specialized applications. Usually, the control software has built in g-codes for using them. I know our Morbidelli supports them, but we don't have one.

As you mentioned, the CAM part would be the biggest issue, as anything that allowed you to do what your talking about would be very expensive, if it even exists.

If you want undercuts, you'll want to look at 4 or 5 axis.

[Frantic Fab]

Julian,

well as for special bits we typically just use straight plunge router bits, end mills, and ball mills, you can always have specialty tools made for super specific finishes and whatnot. but just shy of using special router bits for borders and mouldings sometimes we just use the industry standards.

as for the jig its just another step to any machining process. an example, we make specialty vacuum manifolds for HP that constantly clean their giant rolls of paper before going into the printer. these parts have surfaces and pockets on either side of a 3/8 polycarbonate sheet. to obtain this with our standard 3 axis router with a vacuum downdraft tabletop we take a few extra steps. we also use full 4'x8' sheets at a time so this will work for you as well.

first off you will need a sacraficial bed. we use 1/2'' expanded pvc sheets. this process will depend heavily on the shape of the finished part. say you have a 3'x3'x1'' sheet that needs 1/2'' deep pockets on either side. i would simply make a slight pocket about .125'' deep. this pocket should be exactly the size of the finished outline of your part. once the pockets and part itself is cut out of the face and all the details have been made into the front side, remove all scrap and now the pocket in the bed will house perfectly, in a specific position your part. this allows you to flip the part over, secure it in a specific location determined by your home position in refrence to the coordinates used to make the bed. now you can accurately make more complex surfaces on the other side or your part.

now your surfaces sound much more complex "carving" so in your case if you have a bunch of complex surfaces all varying its going to be tougher for you. but prototyping foam is relatively cheap and durable as well as extremely easy and fast to machine. in your case i would go with foam thick enough to encapsulate the peaks and valleys of your first surface. secure this to your router bed. then for you the next step could be tricky. but essentially you want to take the negative of the survaces machined into the face of your part and cut them into your bed. this way you can take your part minus the undercuts. flip it over and be able to re-establish a consistant home position in refrence to your geometries. now you have access to the entire underside of the part. i use this method all the time to make our 3 axis router do things it normally cannot. using the same methods i can also make the jigs or templates hold the part at given angles and positions. this is the way i can cheaply efficently and accurately compete with other companies that have more of a disposable income than we do. but innovation got us to where we are now. sometimes you just have to think like a robot. these machines do only what we tell them!

feel free to contact me anytime! i love sharing and helping others as much as i do learning new skills myself. hope this helps!

Thanks,
Garrett

[JulianDR]

feel free to contact me anytime! i love sharing and helping others as much as i do learning new skills myself. hope this helps!

Garret, thank you for these pearls of wisdom! I can't wait to try a few of your tricks...

[Switcher]

This was done on a 4-axis cnc.

Belongs to another member (whiteriver) here on cnczone.

I think that's about as complex as you can get with a machine that has less than 5-axis.

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