Advice appreciated - buying CNC mill on the cheap

Hey PM owners,

I'm starting my own shop and would very much appreciate your opinion on thrift-shop tier CNC mills.

Here's the situation: I recently became unemployed and have decided to strike out on my own. I have ten years' experience in CNC manufacturing, started as a button pusher and worked my way up to setting up/running/editing programs for a 9 axis millturn center doing military aerospace work. Got an engineering bachelor's degree and worked for two years as a manufacturing engineer for a major metal products company. No experience running a business but pretty good at designing parts and making chips. I'm relatively young and childless, wife can pay the household bills with her job so I think it's a good opportunity to take a swing at ownership. I have my own products which I wish to manufacture and sell, not interesting in job shopping. These are primarily milled parts. For turning purposes I have a Mazak QT10 lathe which I rebuilt in my spare time that is ready to go. I need to find a solution for CNC milling - I have a series 1 Bridgeport manual, but am under no illusions about my abilities as a manual machinist or ability to make parts competitively on a manual knee mill.

I bought a Bridgeport Interact Mk II off of Craigslist for a very small amount of money. The control powers on but is non-functional due to a faulty spindle motor VFD and a missing relay signal somewhere. I've spent 20+ hours crawling through the control cabinets with my multimeter but can't find the fault. Control is a Heidenhain 2500, I've run them before but not really a fan of 1980's conversational controllers. I'm not willing to put money into fixing the controller, I'm parting it out on Ebay. The mill is physically in decent shape. Ball screws look bright and new, spindle turns freely by hand with no noise or resistance, limit switches all function, ways are bright and flaked, only a little surface rust on the table and some gnarly paint. Servo motors are present on all 3 axis, condition unknown. Sometime in the late 90's this machine was retrofitted with a 10HP spindle motor and Baldor VFD.

I have the option of restoring this machine with a retrofit kit, the Centroid one offered by Ajax looks pretty good to me. About $4000 for the kit, and I'm confident in my ability to install it. However, it still has some limitations: No ATC, no enclosure, not sure how hard I want to push a 10HP spindle with 30 taper tools, and the rigidity limitations of a knee mill.

I would dearly like to have an ATC so that I can load a part, hit go, and then do something else while it runs. An enclosure would be great for mess containment; I have no objection to mopping but it's not a profitable use of my time. What I'm really looking for is a used VMC or HMC as cheaply as possible, or a functioning CNC knee mill for about the cost of the centroid retrofit. Not really considering Tormach, by the time you add ATC and enclosure you're up around $14k and are working from steppers instead of servos. How cheaply and from where can a machine like this be had? All advice appreciated.

Just go buy a Fadal.. Pretty damn cheap to get... And comparatively CHEAP to fix... And you are finding
out that repair costs are important.

They were essentially the same machine FOREVER... So support is EASY to get... They made a metric butt load of them and
lots of parts are common over large spans of years. There are at least 5 different companies
that sell/repair parts and also offer FREE tech support.. You can get tech support here for free also...

And when I say CHEAP parts, I'm not talking $5, but compared to most machines out there, the parts are dirt cheap.

* All standard Fadal Disclaimers apply,
Its not a Mazak, its not a Mori,
The tool changes will put you to sleep
and the rapids aren't awe inspiring.
Its a commodity machine, and will perform
very well for you if MAINTAINED PROPERLY

Buy a used name brand VMC with a tool changer. Don't forget you will need tool holders, vices, measuring equipment, cutting tools, ......... the list never ends.

I bought a 1994 Fadal VMC10 without knowing a thing about VMCs... Trucked it into my shop and set about cleaning it up... It's had a hard life and had a variety of problems including a spindle that's been crashed multiple times and also gone badly bellmouthed (likely due to inadequate drawbar pressure). This machine had a hard life, zero maintenance done on it before I got it and run with synthetic coolant which dissolved the paint and rusted everything.

Despite all that the machine runs surprisingly well, can still take a cut even with no work done on the spindle (ie: 1" deep cut in 1018 at decent feedrate, no problem). It has limitations, like it doesn't like doing 3D surfacing at high feedrates (over 70ipm) for long periods of time, but apart from that it runs like a champ and has become the core of my business.

After getting it I pulled it apart and replaced a bunch of worn stuff, the repainted the machine to get it presentable. I've just recently bought a brand new spindle for it ($3400) which will soon go in. New spindle is better than the old one was when it was new! 12k RPM rated, air purge and chiller piping built in.

New ballscrews, couplers and thrust bearings will be next. Ballscrews are $875/axis... Thrust bearings are $90/axis. Couplers are around $150/axis...

Point of my long story is that Bobw is right. Fadals are well supported with at least 2 serious vendors for damn near every part on the machine. They're well built and really dead simple both electrically and mechanically. Working on mine has so far been very pleasant and even in it's rough state it's done a lot of good work milling tool steel and composites for my product. With the replacement parts I have no doubt it's going to be pretty darn amazing, especially given the relatively little amount of money I'll have in it. I wouldn't hesitate to buy another one.

What I've spent so far:
The mill: $8k
Rigging/transport: $1500,
Misc spares/replacements: $1000
New spindle: $3400
Ballscrews/bearings/seals/couplers for X&Y axis: $2230

So for ~$16k and some elbow grease I'll have a serious mill in good shape ready for another 20 years of hard work Pretty good overall.

If you're looking at new machines it might be worth having a look at the stuff that Detroit Machine Tools are selling. They have some little BT30 VMCs for ~$20k brand new with ATC and so on standard. Siemens control... haven't seen one in person but they look pretty nice, especially given the price!

MILLTRONICS PARTNER 1F CNC MILL Very simple machine, easy to fix.

I realize this a chicken/ egg question but do you have contacts to get work? or are you cold calling every shop in a 300 mile radius for surplus?

WILLEO6709 said:

I realize this a chicken/ egg question but do you have contacts to get work? or are you cold calling every shop in a 300 mile radius for surplus?

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Don't have work, don't want work. I have designed my own products and want to make them. I have very low overhead and don't have to be the breadwinner of my house. I know plenty of guys who went into job shopping, got heavily in debt and ended up shutting down, and the horror stories they've told me have me running scared from that notion. I don't have niche capabilities to serve other larger shops, and there are plenty of established machine shops in the area who are already lean and hungry and sniffing around for work. Not going to beat those guys. I have a niche product designed that targets a severely underserved market and I like my chances there much better than job shopping.

converterking said:

MILLTRONICS PARTNER 1F CNC MILL Very simple machine, easy to fix.

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Yes, I'm watching that auction. From the auctions I've seen the price tends to explode in the last couple hours. If the buy it now was 3500 I'd pull the trigger. 6500 + 2000 shipping + 500 rigging vs 4000 to re control a machine that I already have. I know it seems petty but I'm working entirely from my savings and need to minimize initial cost. Once I'm making sales and proven that a market for my product exists I can chance financing a modern machine.

I have a retro fitted mill without a tool changer.... NEVER AGAIN!

Your time is limited and waiting around for tool changes, with the prices of good used machines with tool changers so low, is just foolish...

Hobby shop is one thing, making money is something entirely different.

Yep,
A Fadal ain't a Ferrari but it comes with a Chevy price and you can crawl under the hood and fix most anything. The macro language is a version of Microsoft basic too. Qwerty keyboard, simple functions, and lots of them to chose from. What's not to like for what you want to do.

Everyone's saying Fadal, and I've dealt with thirty-something different Fadal VMCs since I was ten years old or so. For the price(got an offer of $5k on one), they can't be beat, but you're going to run into some surprises if you don't expect them. Particularly if you're only use to newer, or high end machines.

First off, the spindle creep is massive and doesn't self-compensate for itself.
The available IPM on them is pretty damn blistering fast for being so old, but the machine shakes like a leaf over 90IPM, so don't expect to be doing a lot of high-speed machining at the advertised rate. Thankfully, they come with some pretty damn strong spindles, so you can hog softer metals without a care in the world.
When you push on the table, it's going to move. Unlike a better machine that will actively position itself, and resist the force.
They can, and do fault. If a machine ever has an amplifier problem and crashes itself every month, it's probably always going to be a problem throughout it's life, even after having a complete electric overhaul. One thing about them crashing, is that they never seem to do to much harm to themselves. If it had enough momentum, it might crack the outer spindle housing.
The spindle might be rated, and spin over 7500RPM, but it doesn't have any real torque above that, it'll bog down skim cutting aluminum.
Very limited memory, so mega programs have to be drip fed, or written in segments. There is thankfully extended memory options if you throw some money at it.
To add to that, it has no look ahead and a fairly slow blocks per minute. So if you're doing a lot of elaborate hem stitched parts, invest in a better machine as soon as you can for those jobs. Otherwise use form cutters where you can(that's good advice in general).

Now if you know what you're getting into. They're great.

I don't know how the Ajax stuff compares to Centroid, I hear it is the same. I have a Centroid M400 on a Bridgeport V2xT knee mill. The control is great, easy to program with finger cam. Not having a tool changer makes you pay attention to how you set it up. I never make more than 20-50 parts so the tool changer deal is not a problem.

Ask yourself this up front: do you want to be a chip maker or machine tool repair business? If you're not careful, you could rely on the former to become the latter. I say this mostly as I think some (I didn't say all!) shops do better at fixing up machines and should do that as a business as opposed to running a machine shop. I fully expect to get some flack over this but the one thing I've noticed about such shops (that tend to "grow" by re-habbing old machines) is that they never do really grow. Too much time is spent on the re-hab (owner looks at eBay and CL all day, goes to auctions, etc. and that's just where it starts) and the sales end of the business never really takes off. The best shops will grow by buying new equipment when capacity, tax, down-time or productivity improvements (new machines being faster) necessitate replacement or addition of machinery. At the business I work (in engineering), the one machine that really makes money is the one we spent $220K on and has never failed in about 2 years and soaked up almost zero overhead aside from programming. We have other machines that have soaked up a ton of my time just trying to get them going (this is more in the world of re-purposing equipment into obscure processes) and it's amazing at how well that old equipment keeps us from focusing on real growth opportunities (automating our quoting process, improving our quality, etc.). Bottom line: if the ONLY way you can keep your business going is by re-habbing old equipment, then you have a bad or at least poor business model.

Now having said all that, there isn't really anything "wrong" with doing this, especially when starting out. It just goes back to my original question: ask yourself what do you really want out of a shop. If you don't mind trying to balance the rebuild world and the running a machine shop world (i.e. getting paid to "tinker"), then stay at that business model. Just don't expect to grow into a $20M shop with gleaming floors and machines replaced about every 5 years. Not everyone wants that either and that's okay. Just don't go down one road and wonder why you can't go down the other.

One other thing, more on the business side of things: Find you local SCORE chapter and get some free counseling on the business side of things. Not everyone has a good experience working with them but I have and so have many others.

Good luck!
The Dude

CrookedRiver said:

...and there are plenty of established machine shops in the area who are already lean and hungry and sniffing around for work. Not going to beat those guys.

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Prototype on the bridgeport and use the shops you just identified for production, at least until your business can justify buying equipment, and when you can make that justification, buy equipment that you can run with... Also, see some of Kevin Potter's posts on how he farmed out production...

Brent

if you have your own parts that you are going to sell why not start off by having somebody else make them and you sell them? In the end if it's you making them or somebody else the cost is probably within 25-30% isn't it? If you have at least a 50+% margin in selling your parts, start on that end and build up your budget to buy your own machine to fabricate them when the sales are at a volume where you feel it's logical to do both. You might realize that having somebody else make them is so good that you can concentrate on design and sales. You said it best, there are plenty of job shops looking for new work, why not use that availability for now instead of continue to be a machine fixer upper?

Just to qualify my previous post, I was in much the same position as you several years ago trying to get a product off the ground. I was held up in prototyping with local shops and ended up buying a VMC and two CNC lathes along with manual equipment. I don't regret it one bit, but if you've got a product ready to go and machine shops that can build it (I didn't really have that option as readily available in a cost effective way), by all means move forward with the product. Don't let finding a machine or getting it going or learning it hold you back. Job number one is to get the product to market and start generating sales. Keep looking for a machine, but get some sales going ASAP...

Brent

powerglider said:

if you have your own parts that you are going to sell why not start off by having somebody else make them and you sell them? In the end if it's you making them or somebody else the cost is probably within 25-30% isn't it? If you have at least a 50+% margin in selling your parts, start on that end and build up your budget to buy your own machine to fabricate them when the sales are at a volume where you feel it's logical to do both. You might realize that having somebody else make them is so good that you can concentrate on design and sales. You said it best, there are plenty of job shops looking for new work, why not use that availability for now instead of continue to be a machine fixer upper?

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I would love to be able to do this, but the products I've designed are firearms and firearm components (NFA), so the only places that could manufacture them are 07 FFLs with the 02 SOT - in other words, my direct competition. I have considered trying to partner with a current 07/02 FFL but everything I've read has been nothing but horror stories about partnerships gone bad. I am considering patenting my devices and trying to simply sell the patents to a current manufacturer, but there are many pitfalls along that path too. If my stuff wasn't federally controlled I would absolutely farm out the work.

The Dude said:

Ask yourself this up front: do you want to be a chip maker or machine tool repair business? If you're not careful, you could rely on the former to become the latter. I say this mostly as I think some (I didn't say all!) shops do better at fixing up machines and should do that as a business as opposed to running a machine shop. I fully expect to get some flack over this but the one thing I've noticed about such shops (that tend to "grow" by re-habbing old machines) is that they never do really grow. Too much time is spent on the re-hab (owner looks at eBay and CL all day, goes to auctions, etc. and that's just where it starts) and the sales end of the business never really takes off. The best shops will grow by buying new equipment when capacity, tax, down-time or productivity improvements (new machines being faster) necessitate replacement or addition of machinery. At the business I work (in engineering), the one machine that really makes money is the one we spent $220K on and has never failed in about 2 years and soaked up almost zero overhead aside from programming. We have other machines that have soaked up a ton of my time just trying to get them going (this is more in the world of re-purposing equipment into obscure processes) and it's amazing at how well that old equipment keeps us from focusing on real growth opportunities (automating our quoting process, improving our quality, etc.). Bottom line: if the ONLY way you can keep your business going is by re-habbing old equipment, then you have a bad or at least poor business model.

Now having said all that, there isn't really anything "wrong" with doing this, especially when starting out. It just goes back to my original question: ask yourself what do you really want out of a shop. If you don't mind trying to balance the rebuild world and the running a machine shop world (i.e. getting paid to "tinker"), then stay at that business model. Just don't expect to grow into a $20M shop with gleaming floors and machines replaced about every 5 years. Not everyone wants that either and that's okay. Just don't go down one road and wonder why you can't go down the other.

One other thing, more on the business side of things: Find you local SCORE chapter and get some free counseling on the business side of things. Not everyone has a good experience working with them but I have and so have many others.

Good luck!
The Dude

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I agree with this 100%. I don't really want to be a machine rebuilder. It might be a fun hobby to generate some side cash someday, but I want to get my designs to market and not keep tinkering with machines my age. Like you said I've spent quite a lot of time on the internet dicking around looking for a mill. I'm just trying to get off the ground, as soon as I can I plan on buying a modern machine that comes with things like warranties and service tech installation!

Thanks for the advice about SCORE, it appears Akron has a chapter and that's reasonably close to me. I'll check them out.

moonlight machine said:

I don't know how the Ajax stuff compares to Centroid, I hear it is the same. I have a Centroid M400 on a Bridgeport V2xT knee mill. The control is great, easy to program with finger cam. Not having a tool changer makes you pay attention to how you set it up. I never make more than 20-50 parts so the tool changer deal is not a problem.

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Ajax sells Centroid stuff, just sans the service techs who come out and install it for you. I think I can get by without a tool changer but it sure would be nice to have one. The place for whom I was a manufacturing engineer has a Cleveland brand bed mill with Centroid controls, quite a lot of the shop's production relies on that workcenter. What I'm considering building would pretty much be that.

with these added details it does look like you do need to get your own equipment, thanks for sharing those.

CrookedRiver said:

I would love to be able to do this, but the products I've designed are firearms and firearm components (NFA), so the only places that could manufacture them are 07 FFLs with the 02 SOT - in other words, my direct competition. I have considered trying to partner with a current 07/02 FFL but everything I've read has been nothing but horror stories about partnerships gone bad. I am considering patenting my devices and trying to simply sell the patents to a current manufacturer, but there are many pitfalls along that path too. If my stuff wasn't federally controlled I would absolutely farm out the work.

Click to expand...