CNC for an Hobby machinist

[Setscrew]

Hi guys,

I'm a hobbyist machinist and I want to buy my very first milling machine. I have a low budget.

I'am looking for a cnc mill capable of cutting aluminum, iron and steel.
I've found 3 interesting milling machine:

1) MicroMill DSLS 3000

2) Standard Dimensions of Sherline Tools

3) LittleMachineShop.com - Milling Machine CNC, Tormach PCNC 770 Series 3


is it possible to machine a 6" X 3" X 1 " HSS Block within hours with one of those cnc mill? (See the drawing of a typical pieces to be machine).

Do you have any tip that could help me to chose the right cnc mill for my application ?

Do you know a low cost cnc brand that could meet my needs?

Wich CNC spec should I target to be able to machine 6" X 3" X 1 " HSS Block within hours?

What about retrofiting a used milling machine with step motor and an open source cnc program (LinuxCNC.org - Home) ? Is it possible to get good price in this way? Like 2000 $ ?

Your help is appreciated.

[Ron Dunn]

"Low budget" and "cutting steel" can't live in the same sentence.

In fact, "low budget" and "CNC" are somewhat distant cousins as well.

The only machine in that list which is truly capable of milling that part is the Tormach. It won't be anywhere near $2000, I think you'll spend 4-5 times that amount just to get started.

Sorry to disillusion you, but I think your expectations are unrealistic.

How many of those items do you need? The hourly rate for machining is pitifully low. Perhaps contracting out the work might be a better option.

[Setscrew]

Thanks for your answer Ron.

Ok, my first expectation were unrealistic. So, let me modify my goals.

At this moment, I just want to get experience with mill as an hobby. I wonder to realise my own projet to get experience. The drawing (TypicalPces1.jpg) is an example of my past project. The flange was machined with laser tool for only 30$. The purpuse of the drawing was only to give you an idea of my needs. Similar geometry could not be machined with laser tool.

Now, My new objective is to start with plastic or aluminum project at the begining. Is it more realistic to find a low cost CNC able to machine an aluminum bloc of 6" X 3" X 1 " ?

Do you have any table that explain the capabilities of the milling process with respect of material?

I have some difficulties to relate the mill specification to the machining capabilities.

Thanks a lot.

[Setscrew]

Else, It would be appreciated to get information on a CNC mill starter kit.

What is a good CNC for a beginer ?

[DiverBob]

I used a Sherline mini mill that I converted to CNC several years ago for quite a long time. It is possible to do a lot with the machine, you just have to work within its limitations! I finally outgrew the Sherline (anyone interested in a used Sherline mill?) and got a Tormach 770 which is a really great machine. With patience you can do a lot with even a small machine and hold .001 tolerances fairly easily. It just may take a while to finish some projects.... Remember, the machine itself doesn't do anything without tooling, it doesn't take long to equal the original price of mill!

Bob

[rowbare]

The Sherline you can pick up with one hand, the Taig with both and you need a crane for the Tormach...

If you are still feeling your way around CNC, a good starting point is the Taig. It is a bit heavier and more rigid than the Sherline and it holds its resale value pretty well. You can get a nice package for around $2000. It is a great machine to learn on and if you decide later to get a bigger machine, you can usually sell it for only a few hundred less than you paid for it. If you sell it after a year it will probably only cost you $20-$30 a month in "rent".

Oh and they make cutters out of HSS so it isn't the best material to be trying to cut...

bob

[keebler303]

Spend some time on youtube and you will see typical projects each machine is used for and how long they take. Almost the exact part you mention: http://www.youtube.com/watch?v=TH26ik0tXH8]Milling 1018 Steel Part with my TAIG CNC Mill - YouTube

And as said above, I would not recommend milling High Speed Steel, which is used to make the cutting tools.

Matt

[Setscrew]

What do you think about this kit?
It looks like a very good starter kit:

Central Machinery 1-12 Horsepower Heavy Duty MillingDrilling Machine(1200$)
Stand for MillingDrilling MachineShipping (160$)
R8 Collet Holder (Chuck) (50$)
4 Piece Collet Set (18-516) (50$)
End Mill Set, 6 Piece 2 Flute (20$)
Clamp set to hold the work pieces (60$)

Do you have any Ideal of the precision of this tool?

If the machine is enough good, It could be great to retrofit with step motor to get a CNC. Than, I could use the (LinuxCNC.org - Home) to program my CNC.

What are the recommanded step motor torque and speed for this kind of mill?

My project is growing fast. I become interesting.

Does my project make sense?

[morgandc]

Many people will recommend a square column mill so it stay in alignment while raising and lowering the head.

[TarHeelTom]

The other thing to ask is how much space do you have available.

If you've got lots of space, you might want to consider a used Bridgeport. They come up on craig's list almost every day, and at some pretty reasonable prices. I will tell you that when you find the right one, you need to be prepared to buy it TODAY!

The Bridgeport will do everything you're trying to do, plus more.

Try and find a Bridgeport (or clone) which was made with cnc to start with. They are a lot easier to rehab than to convert.

If you don't have room for the Bridgeport, then you just might have room for the Tormach, and it is an excellent choice, IMHO.

Tom

[Setscrew]

Good point morgandc,

I have found an post on CNCmentor : CNC Mentor.com: | Blog | Docs | New Doc

"A round column mill is similar to a drill press in that it uses a round column to support the spindle. Z-axis moves are made using a quill because the spindle cannot be moved along the column without losing x and y position. They lack the rigidity of kneemill style mills and are plagued by tables and heads that move under load. This makes these mills less desireable for CNC applications, because the entire machining operation must be completed without moving the Z-axis except via quill, which has very limited travel."

Thanks for your answers guys !