[wickedeng]

After months of scouring the cnczone forums, I'm finally ready to make my big purchase. I'd like to buy a cnc mill, but there is one factor I just can't decide on....a used (and old) VMC, or a CNC "knee" mill.
I work as an engineer in an industry which rewards my creativity and also gives me a market to sell my newest dodads.
With that said, i don't expect to put a cnc mill in my garage and watch the money roll in, however I do have a somewhat unique situation; My boss will more than likely (well actually he will) award me the rights to produce small brackets etc... used daily by our shop. This will by no means amount to thousands of pieces per order....but doing multiple small jobs will likely amount to 500-800 pieces per month. Most everything we manufacture is made in 6061. Very limited production in 7075 and 2024 (on the order of 100 small pieces per year). Some basic mounting brackets are made from CR/HR steel up to 3/8" thick.
Most items we make have 1 to 5 thru holes. Some tapping will be required though (up to 3/4). Designs are generally simple....they could be made from a 2D sketch all day.
Generally products would fit easily into a 10X10X5 work envelope....however some of the more lucrative pieces we pay more for would require something on the order of 30X20X5.
I'd like the ability to fixture multiple small pieces at once if at all possible.
Almost everything we have milled is from 1/2" - 3/4" thick extruded bar stock.....our parts have various radii on the profiles just to keep them from being square and boxy (simply for style). We fillet/shoulder mill/round/chamfer almost all profile edges.
Accuracy is typically on the order of +/- .005.
Our current vendor (another home based shop) can't hold this so I'd win more work if I could.
I have the cad/cam side of things well covered and have finally lined up the finances to make a machine purchase.
I really would only be making 2D brackets with rounded edges....holes would be limited to 3 or four sizes so i'm assuming i can begin with a low inventory of tooling....which of course i would like to build further in the future.
At some point in the next year or so (as my machine operating skill permits) I'd like to create slightly more complex pieces for personal use.....contoured housings, drive hubs, etc.... for go-carts etc...
My workspace is a 14'X22' garage (7' door) 10' ceiling. I will put in a bigger door if need be.
3 phase power is out of the question....but a 1 to 3 phase converter is not.
I'm initially agreeing to machine some one off pieces for free (material provided) until I'm skilled enough for this light production work which i will be paid for. Really, these parts aren't over-complicated and I'm pretty confident that with the right equipment and a bit of time i can do as good or better than some of our vendors.
I have 12k-15k at my disposal for a initial purchase.....and i plan to slowly build my tooling inventory from my pocket.
I would absolutely love to stay under 10k.
My wife would love me to stay under 8K.

Given all of the above:
1) Am I crazy
2) Should I look at a cnc knee mill or older VMC
3) Will i regret the lack of auto tool changers etc if i buy a CNC bridgeport etc?
4) Given my applications do you think auto tool changers, full enclosures, flood coolant etc etc etc are wise options to want?

I've been looking through brokers (would rather not go this route) in classified ads and on ebay for about 4 months now.

I've seen every type of mill under the sun for sale, then subsequently convinced myself that "this is the machine I need"

I just can't decide what side of the fence I want to be on.

There are CNC bridegeport mills in my area that are on the very low end of my price range (i.e. 2-5k)

There are mid 80's/early 90's VMC's in my area (supermax, bridgeport etc)
for around 10K

Accuracy and the abilty to ensure i can keep this thing running for at least a few years are concerns of mine.

Any advice?

Thanks for reading.
Sorry for the rant.
Regards,

Bob B.
4)

[jmelson]

Given all of the above:
1) Am I crazy

No.

2) Should I look at a cnc knee mill or older VMC

Well, I think most of your work will do fine on a Bridgeport. The BOSS CNC systems had rather limited X travel, like 18".

3) Will i regret the lack of auto tool changers etc if i buy a CNC bridgeport etc?

Hmmm, maybe. There are ways to get around it, like do all your operations with one tool, change, then run all parts through again with the next tool. With the volumes you talk of, a tool changer might be a good idea. But, with a quick-change spindle, it would only take you a couple seconds to change the tool manually. If you can get a couple dozen pieces stacked on a custom fixture on the machine, it could run for quite a few minuted before needing a tool change.

4) Given my applications do you think auto tool changers, full enclosures, flood coolant etc etc etc are wise options to want?

There are CNC bridegeport mills in my area that are on the very low end of my price range (i.e. 2-5k)

There are mid 80's/early 90's VMC's in my area (supermax, bridgeport etc)
for around 10K

Accuracy and the abilty to ensure i can keep this thing running for at least a few years are concerns of mine.

Well, first, all old machines are subject to wear-out of the electronics, often before the iron. Do you know your way around this stuff? If not, it can get expensive very quickly. If you know your way around it, then you might buy an old machine and retrofit it with a PC-based control. That would allow you to maintain it indefinitely. If it is some proprietary control, it might become totally impossible to get repair parts, or you'd be left at the mercy of the vultures that will sell you used boards for $4000 each.

If you are going to buy a used machine and run it as is, I'd definitely get one of the more popular machines, as expertise and spare parts will be more easily found. Old Bridgeport BOSS machines can be real nightmares. Their old controls were rather poorly designed, and sure didn't improve with age. The EZ-Trak units were better, but some of these are also pretty old. If major stuff pops, it can still be tough to get it fixed.

Jon

[ppascuzzi]

The work envelope you mention is pushing it for a Series I Bridgeport eztrack, a series II would cover it BUT if you get one of them get a Series II Special, it has a series I style head. The regular series II head is next to impossible to get mechanical parts for.

As a repairman my preference would be a used mill with fanuc controls and drives. (check drives and control as some machinetool builders would use fanuc controls and then go cheap and use someone else's drives) Parts and rebuilt boards are readily available for them and they are very durable, which is not always the case with other controls or drives. If a drive goes out it is possible to retrofit another drive in but if a control goes out it can be expensive to retrofit a different control if the original is not available.

[dblox]

I spent several years lusting after a Tormach or IH mill with plans to start a part time business on the side.
I work in an R&D department for an electronics company. Quite often I'd design an electronic test fixture to be machined by our local CNC guy, which got me interested in the whole CNC subject.
I had it in mind to buy a machine, learn CNC and sub the work out to myself.
Prior to purchasing my machine I had no machining experience or knowledge of CNC.

However instead of buying a smaller (hobby) brand new machine, I bought a used VMC with tool changer, big spindle (BT40), large travels (850mm x 510mm x 510mm), very heavy (5200kg), 3 phase and all that.
9 months later, those little jigs I thought would sustain me are about 5% of my current workload.
I know you said you couldnt have three phase plumbed into your house, but don't limit yourself by buying a machine which isn't enough of a workhorse to get you a few different customers when the opportunity inevitably presents itself.
Toolchangers, rigid tapping and fast rapid speeds are very, very nice to have.
If I had to do it all over again I'd buy a used VMC for sure.
If you have what it takes to find the work for your machine, be brave.
You said you had a wife, I'm fortunate (if you want to see it from that perspective) in that I'm not committed to anything, which means I am free to stay up all hours of the night machining my jobs.
If you want to grow a business I'd say buy a used VMC.
If you want to stay as a secure family man which trades some spare time for pocket money, buy a smaller bridgeport or similar.
Have you considered buying a larger bed mill with something like a centroid controller? Or a HAAS TM2?
This would be good middleground, although the machines are expensive, they will retain their value should your plans go belly up and you need to sell the machine.

[gus]

You will find quotes from me on some sites from 10 years ago saying 'buy a cnc knee mill'

Not any more.

If you have the room, vmc's are too cheap to pass up.

they can cost a bunch to fix if they break, but you probably won't stress them for some time

[SCzEngrgGroup]

You should buy the biggest, most capable machine you can possibly afford. Doing any kind of volume production without a toolchanger will quickly become a real chore, and cost you accuracy, as you will pretty much have to resort to doing operations with one tool on a quantity of parts, then changing tools, and re-fixturing all those parts for the next operation, etc. Unless you have unusual parts where there is a LOT of machining to be done with each tool, the toolchange time, will become a major factor in your overall production rate, and you'll be stuck "baby-sitting" the machine the entire time, which becomes REALLY tedious REALLY quickly. If you're seriously going to be making hundreds of *anything*, a VMC is the only way to go. And your choice of VMC, and the collection of accessories you get, should be driven by the parts you intend to make. Reaching a reasonable production rate on all but the simplest parts will also require spending quite a bit of money on dedicated fixtures that hold a lot of parts, and minimize the number of re-fixturing operations required to complete the machining. This is where I spend most of my time, and get the most benefit.
Also, don't overlook the learning curve. Learning to operate one of these machines efficiently takes a LOT of time and a LOT of practice.

Regards,
Ray L.

[wickedeng]

thank you all for your imput so far.
I have to say I'm once again leaning towards a VMC, though the prospect of a computer control or electrical nighmare is a bit tough to swallow. I'm willing to work with the smaller work envelope if it means a more reliable machine (i.e. newer machine). With a little more investigating it looks like i might have a tough time finding a suitable VMC that isn't actually more than i need. While i can appreciate speed, HP, and faster cycle times, some of the used VMC's i see in my price range are simply more than i need....or at least i think. The classified section of this site has a daewoo vmc in my price range but at 20hp it is a hulk of a machine that might be a bit much. There are local hitachi (mid 80's) and supermax (mid 90's) for 5 and 10k respectively but they do concern me. I'm afraid the supermax might also be a large HP machine that will require a very significant electrical commitment. The hitachi is old, and at 5k i'm a bit afraid i might be in over my head as far as needed maintenance. I'm not familiar with cnc repair or construction, but that's not to say i wouldn't quickly become so. I typically thrive with electo mechanical problems (and have somewhat of a background in the area) but if i don't need to deal with the hassle I'd rather not.
Anyone have any suggestions as to what direction I might need to look for a VMC that would fit my needs and not overwhelm me? Surely there must be a brand of machine that is commonly seen used that i should be looking for?
In regards to pricing....I know that if i spend just a bit more and creep up on the 20K range many more options will open up, i really just don't want to do it. I'm willing to make what i feel are strong risks (money wise) but at some point I just have to draw the line. While i feel this is all pretty well thought out I do have a family to consider and don't want to expose them to any more risk than absolutely necessary. I suppose I could just go for a cnc bridgeport if that is my mind set, but i don't think it's too out of hand for me to step into a VMC. Am i wrong?
Thanks again for the help everyone.
The closer i get to making a purchase (hopefully within the next 6 weeks at worst) the more confusing this all becomes!

[wickedeng]

I can't believe i never looked a mazak vmcs. It seems as though a early 90's/late 80's vqc 15/40 might be what i'm looking for. Any thoughts?

[Jackal66]

There are some Mori Seiki Mv series cheap, on Ebay right now. The ones I've ran are great. The toolchanger is simple, and the rest of the mechanicals are easy to work on. There are some weird things about running the toolchanger manually when it crashes or gets out of time.
There are a lot of independent technicians out there that have these machines memorized. When the factory stopped some of the support, these guys are still there. They know what will interchange from another brand of electronics. The factory does still make most of the ballscrews, etc. The bearings and common wear items are off-the-shelf.

Make sure you get all of the manuals you can with it, or buy somewhere for it.

Also the Matsuura's are rugged and simple, and the Fadals are really easy to fix. There is a website of ex-Fadal engineers and mechanics, that sell Fadal parts, + plus their website has electronic and mechanical diagrams of everything. It is similar to a Chilton manual on a car.

I really would like to have a Mori MV JR in my shop. Maybe someday.


JAckal