Buying my first CNC, your input?

[Cellar Dweller]

Hello Everyone,

New to the forum, but a long time reader. I have a few basic questions with regard to entry level cnc equipment.

Quick background on me first: I am one of those QC guys that everybody loves! I work for a good size company specializing in plastic machining. I am not a cnc programmer. Have average amount of time with Hand Machines. Program Pc-dmis, run cmm, and all typical stuff in QC. I have access to a handful of programmers, set up guys, etc. So this new hobby should be well supported between friends and this awesome web site! Use Solid Works all the time, have legit access to Master cam, and a few others. Just wanted you to know a little about me to consider in any feed back.

My project:
I want to buy a CNC VMC for my personal shop. I need to have a machine that can hold +/-.002 over 4-6 inches in x, y, and the same for about 2inches in the z. I mean hold it, for real. Considering a few old Junkers we have at work, this does not seem like a tall order. Our newer stuff does many times better of course.

Tormach, IH, type machines verses a 10-15 yr old “real” machine. My price point just for the machine is around 10K. I know you can get IH, Tormach, etc nicely fitted for that number, but I am wrestling with the idea that I would be better suited with a 15 year old Mori, haas, VMC. In this current market, if you have a trailer and know how to rig, you can find older machines in that same price range.

The older machine is not new, it will need attention of course, but it will have a ATC, and will have been designed to be a production type machine from day one, have a full enclosure for real flood coolant, a larger work area, more HP, and so on. That is my thinking anyway.

I am looking at some Bridgeports, like the mid 90’s 308 with DX-32 controller. There are a bunch of them around in various states of condition. You thoughts?

I want to be able to do full 3D, all 3 axis at the same time, for my projects. Can the dx-32 controller handle that? If not what would be required for such full 3 axis motion on an older machine?

Thanks for your feedback in advance,
CD

[DSL PWR]

If you have the room get a real VMC. I'd look at Haas and Fadal. I know there are many higher end machines out there, but with the Haas and Fadal you will be able to get parts for them, in a timely manner.

[Cellar Dweller]

Thanks for the input. Parts are certainly important with a 10+yr old mach. Maybe some people can give their opinion on brands which are the best and worst to get parts.

Anyone like to weigh in on the 3axis or 3d sculpting capabilties of older machines?

Thanks again,
CD

[cjdavis618]

Also keep in mind the expense to power one of the VMCs. If you are talking something even a small unit with a 7hp spindle, you are going to need 3 phase power or a CNC rated Converter to power the machine. If you go with the Converter, you will have to add a large 220 volt circuit, which could possibly require you to increase your electrical service to your house. Where I lived, they wanted $1500 to put in a bigger transformer, then I would have to run bigger power cable, etc, etc. this was simply to add an extra 100 amp circuit for a Mori MV jr running from a rotary converter.

Plus rigging the machine into your shop, etc. These things are usually 8k lbs or more. You can burn through your budget pretty quick getting the power and rigging, then not have enough to get tool holders and tooling etc.

Just something to consider.

[Cellar Dweller]

Yes, power has been considered. We have 3 phase in one building, and if it does go to my home we have a new 200amp service, with a 200amp sub panel in the garage. Sounds weird, but that's what I had them put in. I did not want to be sort on power in the shop at my house and it was not much more in materials. ( a heck of a lot of time though. LOL) Good thing the electrician was a good friend, and everything was properly done, permitted, and inspected so we have the watts in a covenant location, but have to invest in a rotary phase if it does come home.

Rigging, is no big deal for us, again between friends and prior experience we have the trucks, equipment, and experience to handle about 10Klbs with comfort, beyond that, I will be sweating...

Maybe the reasons you mentioned are why people buy a new IH over and older, much older, Haas, etc. Rigging, space, and power aside, to me it seems clear to go for the older machine. I hope I am not missing to much.

CD

[cjdavis618]

That's what I like to hear. Then by all means, get the big stuff.

Just be careful and check your gcode and numbers twice. Crashing the big ones can be much more painful than the smaller units.

[greeder88]

Here is the scoop- You will give your left arm to have a tool changer later. A cnc can only cut with one cutter so a huge machine may be wasted 99% of the time. On the other hand you can't do a big job in a small machine. Motors cost $1,000.00 on average so if you buy an old machine how much time is left on the motors? You have to decide how tight of tolerances you need. Old machines have backlash, spindle bearing chatter, and other stuff that isn't cheap to rebuild. It all depends on what you want to machine.
I like Bridgeport series 2 size cnc machines- 15"x30" travel as a medium size, do all machine.