CNC and 3d printing.

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b8factor
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CNC and 3d printing.

Post by b8factor »

I might be on the wrong area? But i had a not so simple question to ask. I was looking to have a 3ds spaceship 3d printed to make mold and cast. I have done plenty of research on pricing between .02 and .006 machines and had just about signed off on moving forward.

Then i stumbled on some affordable CNC machines that are under the price to 3d print the ship. They even take in the same STL files and help chop up to acomodate the model pieces. At first glance it seems like a no brainier, why not spend the money on a machine that I can use over and over. But I am sure there is more to it than that?

At lunch do not have the 2 machines I narrowed down in my head will post later but one prints 17"X17" at .002 depth just over half inch. The other seem far more versatile but only prints .006 and a couple inches deep. Since my parts have high detail I was wondering if the .002 would be better but the .006 machine has been out a lot longer, does a lot more, and looks far more scaleable.

If anyone has any ideas I would love to read about them, or if you know another forum more catered to CNC that would be good too. It is a new topic for me but looking at the videos, software, etc it looks like a fun and interesting thing to get into. I would hate to spend a few K for 3d printing when i could have spent the same and made model after model, as well as everything else it can do.
Tankmodeler
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Post by Tankmodeler »

with multi-axis CNC milling, the resolution you can get on a surface is dependent on the size of the cutter (usually a ball cutter) you use and how small the step size is that you use to space the passes over an area. The limit of teh machine is defined by how small the stepper motors can make the spaces between cutter passes. If teh CNC rig can step less than 1 thuo (.001") then you will get a really good surface. If it can only step 2 thou (.002") the you will get a rougher surface.

Setting the pass spacing very fine on a mill can get you a really nice surface finish, but the parts weill be on the mill for a very long time. The finer the spacing, the longer it all takes.

Only you can tell if it's good enough for what you want to do. With the .002" and .006" layer 3D printed parts, you would defineitly have to clean up every square inch of exterior surface in order to get smooth castings after moulding. That's a LOT of work. The work to smooth the .006 layer parts is more than 3 times that for the .002 layer parts. I can tell you that from experience.

Mililng extremeyl fine detail will be significantly more difficult, if even possible, than making the same complex and delecate shape by 3D printing. The Mill will not produce some shapes in some materials.

The only real way to assess if any machine is going to do the job for you is to get a complex part made by both processes and evaluate them yourself.

HTH

Paul
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djdood
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Post by djdood »

CNC milling also has limitations on what shapes/forms you can create, much more-so than 3D printing. Things like undercuts, etc., are much harder to do with milling.

The cutter head has to be able to access the face to be milled. For complex shapes, this drives into much more expensive 5-axis machines (compared to the much cheaper 3-axis ones).
Pics of my gaming minis, etc. at <a href="http://www.djdood.com">DJdood.com</a>
b8factor
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Post by b8factor »

The two devices are the Click-N-Carve(whole line) and the Carvewright. I see I misunderstood some of the information. The depth(half inch) is the depth it can cut per pass not total depth but most units I can afford have a total depth of 3” which is plenty okay with me.

I am not quite sure how to relate the accuracy of .002 and .006 on these CNC machines to the accuracy of .002 of a 3d printer?

From what I have learned so far, for my purposes, even when using a 3d printer I need to slice and dice my models in such a way to lower costs(height, Length, considerations for molding, creating logical parts to make a sellable model). I see that using a CNC the slicing is done as well but sometimes for different reasons. Since it is an elimination of material I suppose it pays to plan out a board (wood, styrene, or renshape) to take advantage of the full sheet. But also with the CNC cutting limitations there needs to be work done to create pieces that can be put together in a way to accommodate undercuts or diverse shapes in the model after cutting the parts.

One of the things I like about the CNC machine is that it is far more hobyist friendly from the standpoint of there are a plethora of machines, parts, software, and etc out there and the cost can be controlled some. Not to mention you can mill a working part instead of just a model of a part that then needs to be molded to make the real part as done with 3d printing. That being said I am sure it can also become a headache and money hole with repairs, material, tooling, etc. The real attraction with CNC is I can actually afford to buy a device to play with that has the potential to be “useful” where that does not exist “yet” for 3d printing.

Some valid points above, I think I am going to try to seek out an owner of a CNC sharp pro plus and see if they would not mind milling me two small parts (nose piece of my ship) with some reshape I already have. And then go ahead and have the same parts printed by the .002 machine and study the differences. Thanks Tank, I almost sent you this post link in a private message but then decided I have bothered you enough on another post. Glad you stumbled across and took the time to write, You are a wealth of knowledge.

I have been taking daily lessons from my 3ds artist and am starting to become familiar with the software. No matter which tool is used I am finding out that a lot of time and cost can be controlled by the digital design side.
b8factor
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link to add

Post by b8factor »

http://www.carvewright.com/2010CWweb/id ... es/stl.php

In this gallery I see examples that make me think I could use this for model making, but much like the 3d printing would require lots of clean up after.

This particular machine is not as accurate as others in same price range.

I would think that using a jig you could easily slice up an entire piece of styrene into precise parts to put together versus having to hand cut with razor and then sand down to the exact angle.

Your right i need an example from both to compare! My 3ds guy is finally caught up and starting to detail the rest of my ship so I am getting close to making some choices.
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Kylwell
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Post by Kylwell »

From what I remember from the last time the 3D carvers came up it turned out that they're really made to carve wood which is far more forgiving than just about any other medium. They're CNC-lite kind of machines. You can do some neat stuff but they prefer to mill bas reliefs. Mind you, this was 2 years back or so, may have been last summer so things could have changed.
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b8factor
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Post by b8factor »

you may be right about the CNC, but i did stumble on to this guy's blog and it was illuminating!

http://lcamtuf.coredump.cx/rstory/

http://lcamtuf.coredump.cx/gcnc/

http://www.flickr.com/photos/candy-bott ... 20/detail/
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