a million questions about starting cnc

[IJ.]

Data: A good example I found (remember I'm a total newbie) was a simple file I'd saved as an STL, DeskCNC converted it to G Code and it was around the 28.000 lines the same part as a 2d DXF converted to one pass of 26 lines and one of about 30 !

There are times when you'd use 3d cutting but in a lot of cases 2d+ depth (2.5d I believe is the term for this type of pass) works very well!

[HuFlungDung]

I can't imagine running an STL mesh as machine code. It would be very hard on the machine, and would probably look like hell. I've never done it of course, so I could be quite out to lunch.

BTW, since we are talking about expensive software here, and future purchases (after the student priviledge has expired), then I wouldn't go blowing a wad on Solidworks, and trying to skimp on the CAM software. That is why I say OneCNC is a good balance (pricewise) for both modelling and CAM together. This is only one choice of many possibilities out there, so I don't mean to be tramping on anyone's favourite software combo.

[Data]

HuFlungDung, I completely understand your point, but onecnc is completely out of my budget and wouldn't fit into my plans.

you see, I don't worry about SW expiring in two years from now, maybe I'm not even in this hobby anymore by then (remember it's just for my hobby).

I figured to get my feed wet in cnc and related activities, I will start taking classes at local schools (very little money)
then I want to buy a mini lathe (about $500.00) and a mini mill (about $500.00), some tooling over time and practice making some simple parts.
after doing that for awhile, I can determine if I want to go all the way to cnc and convert my mill for maybe another $500.00.

If my decision is no, then no harm is done, I will know a lot more about cnc then I knew when I started, I will own a couple machines that will always have some use and I will know about a cad program that I might use for a long time to design parts for fun or not.

now, if I decide to go all the way.
I will then learn how to convert a mill to cnc, buy some additional software (like meshcam) for a couple hundred bucks and start making my own parts in cnc.
if it is within my budget at that point in time, I will then buy a cam software like onecnc that is well known at that time.

if my budget is to small for a good cad/cam program at that time, I'm sure there will be other options available.

you see, the last thing I want to do is:
buy a cnc ready machine for $6000.00, buy a software package for another $4000.00, brake my bank and charge my cc up to the limit and make a couple of parts just to find out that this hobby is not for me and sell it all for half the price.

the other way (the way I'm going to do it), I have time enough to find out each step involved to make a part without braking the bank and I can back of at any time without really losing anything.
every $$$$ I spend until then will have been worth it just for the experience gained.

if I don't like the design part and I don't want to spend the time on a cad program, I will have paid $179.00 to find out.
If I don't like the lathe and/or mill work, I will sell it again, might lose $200-$300 and will have paid for another experience.
if I go all the way to cnc, I did the machine work and cad program long enough to know that I want to stick with it and there is a high probability that I will use it for a long time.

This is my plan to approach the cnc thingy.

[rustyolddo]

Data, I'm kinda in the same shoes as you. I'll offer some knowledge I'm getting on my quest. First, you can get into CNC real cheaply by picking up one of the many controller boards/kits on the market. I got a 4 axis controller for $120 and some steppers for $100. My plan was to build a simple 3 axis demo machine but now I'm planning on converting my mini-mill. I have acces to a Bridgeport Seris II CNC mill in a maching class that I've enrolled in. Anyway, what you may want to do is build one of the inexpensive CNC router setups. Not nearly as labor intensive as converting the mini-mill; along with adapting the motors to the mill, you'll have to adapt ball screws & improve the gibs in most cases. Your hardware will still be usable for the mill if/when you get bored making sawdust.

As for software, you can do the basics with turboCNC driving your controller, it's shareware and worth the $20 registration. You can hand write the code in a word processor and dump it directly to turboCNC and make chips. At least you'll get a good understanding on how NC maching works.

As for the 3D software and CAM software, I'm struggling with that right now, both with cost issues, and finding the right package. The OneCNC XR Express is $1500. The more I look into it, this really isn't that bad. I can save my coins and wait until I can afford it (a little tough since a need a TIG welder right now as well). If you can find a 2D CAD program that dumps a dxf file, you can use the free ACE converter to convert the file to G-code and run your mill. Keep In mind too, that there is a lot to learn as it pertains to doing the setup and jigging in the mill. A friend of mine who runs a Fadal VMC says the worst part of it all is making the fixtures. I can tell you first hand, from using the mini-mill manually, that you have to do a lot of adaptation and creative setup to make parts, even average size 3"x3" parts since the x-y movement of the mill is so limited. I'm trying to advance my machining knowledge into CNC for the purpose of making multiple pieces of the same part. AS for one-of's, it can be a waste of time to do things with CNC, not counting complex curves and profiles & engraving whcih just can't be done easily with manual methods.

So, my suggestion is to get a low cost quality controller board, I just posted a review of one I like. Get some motors in the 200oz/in range, and pick up the plans for one of the router systems and go to it. you'll be in the game cheap. If you find it is driving you nuts trying to make anything, you won't have alot invested. If you get the hang of it, you'll be able to make some awesome signs and engravings and perhaps sell enough to fund the jump into metal CNC.

I've got a few product/accessory ideas that if I can make them happen, I'll have funding for a real VMC and trimmings to go with it. (BIG Dream!)

[ger21]

You can do a lot with 2.5D CAM as well. Download Sheetcam while it's free, at http://www.sheetcam.com , and get a cheap CAD program like TurboCAD or DesignCAD, and you'll be on your way. You can add MeshCAM if you need it for the parts you want to make.

[rustyolddo]

There is a neat free software package at emachineshop.com as well. It will dump a dxf file but won't retain the 3D info. Pretty nice 3D design software for a beginner.

[Mike Stevenson]

For 3D modeling buy SolidWorks. You won't be sorry.

[wwendorf]

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[The Blight]

This topic is over 3 1/2 years old. I don't think they are going to read it or reply.

Necromancer