CNC milling machines

[TrevS]

Hi all

I was wondering if anyone on here had any experience in using CNC milling machines for car projects? I am thinking of having a workshop built at the back of my house and a milling machine looks like it could be a great tool to get to help with custom fabrication jobs.

If you could give me some basic info on CNC milling machines, types available and the typical sorts of costs involved that would be a good place to start. Also in terms of operation how difficult are they to use and to take your 3D model files and prepare? Finally what format do the models need to be produced in, CAD, 3DS max etc?

Any info would be much appreciated

 

[flatchat(Chris)]

Capacity (for most car stuff ) 1000 X x 500 Y and Z and optional 4th axis (Rotary)
Good compressed air supply, coolants and 3 phase power
Various work holding devices - vice , clamp kits, chuck etc
Cutter arbors or holders - collet type
Cutters --solid carbide end mills 3 - 20 mm dia, 50 dia tipped face mill, drills 1-12mm
Tool setting probe, measuring gear, parallel bars, dial indicater
A big swarf bin
Most late date machines have a good "conversational" control for on board programming as its mostly 2D
3D will most likely need some external software to feed the the machine computer - ether net share. Cad Cam software usually has a licence attached to it and maintenance fees etc
Bridgeport, Colchester, Chevalier, DMG, Moriseki, Haas, etc etc knee, bed, horizontal, turret types.

That oughta give you summit to think about for a minute or so

ps if its second hand, more than 10 year sold you'll have a steep learning curve in electronics. dc drives, relays, limit switches, power supply da da
daaa apart from recirculating slide and screw bearings to lube idiosyncracies

 

[Andy Green]

Trev,
I’ve had quite a few parts CNC’d milled on my car (brake bells & brackets, as well as various engine parts) and for the investment cost & experience required I’ll always sub this work out. A good size mill, as has highlighted by Chris takes up a lot of space (need to allow 2x2m of floor space) and ideally you’ll need a 3 phase supply, or run it from an inverter, which is another expense

You’re better off thinking about buying a lathe first, as this will get a lot more use on a car project (I made over 100 parts – mainly spacers, adapters, mounting pins etc for mine on my lathe). They also take up a lot less space and they’re a good learning ground before moving onto a mill.

Regards,
Andy

 

[TrevS]

Trev,
I’ve had quite a few parts CNC’d milled on my car (brake bells & brackets, as well as various engine parts) and for the investment cost & experience required I’ll always sub this work out. A good size mill, as has highlighted by Chris takes up a lot of space (need to allow 2x2m of floor space) and ideally you’ll need a 3 phase supply, or run it from an inverter, which is another expense

You’re better off thinking about buying a lathe first, as this will get a lot more use on a car project (I made over 100 parts – mainly spacers, adapters, mounting pins etc for mine on my lathe). They also take up a lot less space and they’re a good learning ground before moving onto a mill.

Regards,
Andy

Could you give me an idea of the typical cost to produce some of the parts you had done?

 

[Andy Green]

Trev,
On CNC’d parts it’s all about the set-up & programming time. If you’re already got a 3D CAD model it can easily be converted by the machine shop into the correct format. If you only have 2D or even a fag packet drawing, they have to write the programme, so you’re paying for their time off the machine
I’m really lucky to have a friend who used to run a precision machine shop, but now has a CNC mill in his garage and I do trades with him for my machining. However commcerially it not that expensive. My brake bells would have been around £50-80 each. Compared to a minimum of £5K for a half decent CNC mill (plus tooling which isn’t cheap), it’s not worth considering unless you’re really serious about it
Regards,
Andy

 

[Robert May Eng.]

I get by with a big old lathe and a milling machine. There are not many jobs you cant achieve with these and they are ideal for small volume/prototype jobs. CNC is great but for one offs in most cases you could do the job on a manual machine in less time than it takes to write a program.

Bob

 

[TrevS]

Cool, thanks guys very useful info. Looks like I can save the space for something else then. Maybe another project car

 

[John Milmont]

I have always dreampt of having both a CNC mill and lathe in my own personal workshop. But, its a little more complicated than just going out and buying new machines.
I would first recommend before doing so, that you know how to run manual versions of these machines.

second, would be to know the software. You need to know how to use a good CAD package to develop your models, and then you also need a post processor to create your G&M code (tool paths).

What does a £5k CNC mill look like? I have used some smaller CNC mills, but I'm wondering what £5K would get you? I'm thinking that it must be so small that its barely going to be practical?

 

[Chris Kouba]

I get by with a big old lathe and a milling machine. There are not many jobs you cant achieve with these and they are ideal for small volume/prototype jobs. CNC is great but for one offs in most cases you could do the job on a manual machine in less time than it takes to write a program.

Bob

x2

I have an old manual mill and lathe and the time it'd take to build a model for a run of one hardly seems worth it. If you are going to make multi's, get some software, learn it and send the file to a commercial house. I haven't done the maths but I guarantee you'll be thousands ahead.

That doesn't take away the cool factor of having a CNC mill at your disposal, but it hardly seems worth it. Let someone else make that investment for you. As for me, I paid $1k for my mill and lathe, but dropped close to another grand or so in tooling and fixturing. Decent stuff adds up fast even if it is off Craigslist. That being said, I have easily gotten my $'s out of it and then some.

Chris