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VMC vs CNC Knee Mills

Bakerprecision

Plastic
Joined
Aug 20, 2022
Hi guys (and gals),

New here to practical machinist. I'm a long time fabricator and aircraft structures guy, and I'm getting into the world of machining. To make it better (or worse), I'm starting a garage shop. I don't have to capitol or space to aquire the types of VMC's that I would like, so I'm wondering if going with a CNC knee mill is a good alternative (at least to start with)?

I plan on running as a job shop (repairs, prototype, small runs, etc.), and I will also have a 14x40 lathe, so I'm wondering where the best bang for my buck is as a start up shop.

I've looked at everything from Haas mini mill and TM1, various cnc knee mills and even tormach. While I certainly want the ease of use with a VMC, I think a cnc knee mill might be more versatile in a small shop (I think?).

I'm also diving into the world of gunsmithing, so a knee mill makes sense for this type of work. However, there are a lot of uses for a VMC as well with consideration to custom machining and engraving.

Given I don't have to funds to purchase a VMC and knee mill, which one would you pick? And apologies up-front if this is a beat up topic. I couldn't find anything useful other than the "haas vs tormach" debate.
 
I've used cnc knee mills a lot over the years. As long as you know it's limitations they are very good machines. I prefer millpwr controls but anything will do.

Another thing to look as is cnc bed mills like prototrak offers. More rigid than a knee mill.
 
My first cnc was a knee mill. The biggest negative is having to hand change tools. It’s not very rigid, so you’re not going to break any records milling with it.
I also don’t feel it’s more versatile.

I have 2 4axis vmc’s now so the knee mill mostly sits unless I have a simple job with few tools and longish cycle times.
 
Once you get your head around consistent tool and work offsets plus CAM (Fusion360?), it is a lot nicer to do onesie-twosie work on a VMC than it is to do production on an open machine without a tool changer. A TM-1 with a minimalist enclosure may be an effective compromise.
 
Are there any reliable used machines to be had in the $25k range (I know, it's subjective)? I have an overall budget of $50k, but I'm also purchasing a lathe, tooling and measuring equipment. I know this is a significant cost in addition to purchasing machines. My hope is that I can buy as I need things, but there are a litany of things I will need upfront. Like anyone, having one of everything would be nice, just can't swing it yet.
 
lots of 10 yr old machines for that price.
remember rigging can be a couple grand at each end. plus transportation.
holders can be $200 each. so for 20 of them it can be easily $4000 so there is 35k/50k
then endmills and inserts and other related tooling can be 4K so that is about 40K to get started plus power to supply as 90% are 3 phase unless they are a really small mill.

all depend what exactly you will do, if making gun parts, you need high end precision like a brother and not a piece of junk.to do action parts.
barrels will take a whole different machine and skills set.
manual knee mill will do alot, just takes a bit more manual brain power to complete it and understand it.
 
I am a big fan of the better knee mills. Look for one with box ways and 5 hp spindle. Don't take a lot of floor space and can fit through a seven foot garage door with minor disassembly. I use flood collant with a catch pan below, barriers around the part to stop chips flying around the room. But, yep, no tool changer. On the plus, no huge enclosure as I already got two pounds fo stuff in a one pound spot.

I gave $2500 for a very nice Vectrax with Fanuc control(sold by MSC) at auction.

I'd pay extra for one with a prototrac control. easy to use for a newbie
 
Thanks for the replies and suggestions. I definitely want to fill the gunsmithing need, but I also want to fill the job shop need as well. I figured a cnc knee would allow me to be flexible, albeit slow vs a VMC. I'm definitely buying used as well. After all, the goal is to grow and expand machining and capabilities. Just trying to get a better focus of what machine(s) to start with and best bang for my buck.
I think a VMC would be more profitable, but limited versatility. A cnc knee is slower, but allows for different capabilities. A decent cnc knee costs about the same as a small used VMC, so that's negligible.
I suppose I just need to keep an eye out for a screaming deal 🤔
 
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Made a lot of money on CNC knee mills, but for money invested, now, a tool changer machine is better
When I retire I will probably take my R2C3 knee mill home
For reference on what they are good for...
 
I think a VMC would be more profitable, but limited versatility. A cnc knee is slower, but allows for different capabilities.
More versatile to do WHAT? exactly.. Different capabilities to do WHAT?

Length.. Take the outer doors off. Let it hang.

8535179577_4d464e6ea7_c.jpg


Too big? take the real doors off... And then build a reduction gear box to run your rotary table off a POS Atlas to turn your VMC into a lathe.

8509770303_6d5e05f4c8_c.jpg

I just did another bunch of 32X57 inch plates on a 40x20 vmc.. I had to take the doors off to make it work, but it worked. 3 set ups.. And I charge a premium.

Still too big??? Modify your sheet metal.. Are you a machinist or a button pusher???? Its just sheet metal.
MODIFY it, just like you would modify a socket, or a pair of pliers to do what you needed them to do.. Its just a tool, its not a 1963 Ferrari.. Feel free to modify as you need.

You couldn't pay me enough to make me deal with an open knee mill or bed mill again.. What a mess.
No tool changer.. Never do that again either.. I might need a baby sitter on occasion, but a CNC
machine shouldn't..

Anything you can do on a knee mill or bed mill can be done on a VMC.
Any part that is too big to fit in a single shot on a 40x20 is going to command a premium
to begin with.. Make the modifications you need to, and make some money, without
having to deal with the BS that an open machine brings to the table.
 
More versatile to do WHAT? exactly.. Different capabilities to do WHAT?

Length.. Take the outer doors off. Let it hang.

8535179577_4d464e6ea7_c.jpg


Too big? take the real doors off... And then build a reduction gear box to run your rotary table off a POS Atlas to turn your VMC into a lathe.

8509770303_6d5e05f4c8_c.jpg

I just did another bunch of 32X57 inch plates on a 40x20 vmc.. I had to take the doors off to make it work, but it worked. 3 set ups.. And I charge a premium.

Still too big??? Modify your sheet metal.. Are you a machinist or a button pusher???? Its just sheet metal.
MODIFY it, just like you would modify a socket, or a pair of pliers to do what you needed them to do.. Its just a tool, its not a 1963 Ferrari.. Feel free to modify as you need.

You couldn't pay me enough to make me deal with an open knee mill or bed mill again.. What a mess.
No tool changer.. Never do that again either.. I might need a baby sitter on occasion, but a CNC
machine shouldn't..

Anything you can do on a knee mill or bed mill can be done on a VMC.
Any part that is too big to fit in a single shot on a 40x20 is going to command a premium
to begin with.. Make the modifications you need to, and make some money, without
having to deal with the BS that an open machine brings to the table.
I certainly appreciate your point of view, and agree with it about 95%. My issue is overall cash flow to purchase both a VMC and a decent lathe. In my mind, a lathe and mill (preferably cnc) is basic needs for any small shop. Problem is, I'll only have about $40k to play with initially. I'm trying to find the best bang for my buck, while purchasing tooling as needed.

Thus my dilemma. I can buy a decent used VMC, but I'll likely spend most, if not all of my budget doing this (leaving me without a lathe).

Now I will likely be able to save money made from the VMC and buy a lathe in the future, but maybe not.

Just trying to make informed/educated decision with the budget I have to work with. I know this is very, very subjective, and there are many options on the used market.
 
The machines you buy as a start up depend on the work you have. Or hope to have.
My passion is firearms, so tooling up for this makes sense.

However, I also want to get into repair and prototype work (dabble in whatever), which will likely be more lucrative.

Trying to decide if I want to support the hobby and hope to grow the business, or grow the business and hope to support the hobby (insert crystal ball here)...
 
$40k will buy a lot of good used machines and tooling.

Shop around. You can easily buy a nice CNC lathe and VMC from the 90's or newer and tool them up for less than $40k.
 
sounds like you'd be a great candidate for one of those "I'm retiring and selling my whole shop" deals that crop up occasionally. I couldn't think of a better way of getting fully tooled up in one go if you have that kind of money to spend. It would be worth asking local gun clubs and the like in your area if they know of any gunsmiths getting out of the business. Might even get you some leads for future work too.
 
If you're doing 1-offs gunsmithing and other jobs, IMO you need a standard bridgeport and lathe to begin with. Lots of things aren't worth setting up on a CNC to do a simple operation. If you're doing production of lots of 3-d stuff, it's a different question. I have a Bridgeport Interact 1 (Heidenhain TNC 2500 control) knee mill, which works very well for 2.5D prototypes, as well as a standard bridgeport (Bought it for $5K with a bunch of tools and vise, barely used, about 8 years ago). It won't win any speed records, but is very flexible and accurate when used within its limits. I end up squaring stock in the standard BP and putting it on the CNC. The other convenient thing about the knee-mill for one-offs, is that you can get away with all sorts of clugey clamping, and operating sequences, stop the machine, move the clamps, parts, screws etc. That Interact can be used in a manual mode with hand-wheels, but again lots of things just require a quik setup in the BP. The Interact has Kwick-Switch 200 tooling; although it doesn't have a tool-changer, it makes you be efficient in programming and tool use. Keep in mind you need CAD and CAM software, and the learning curve for that. Also, there's always the specter of a CNC crapping out at any time, so you'd like something that is still repairable, at a reasonable cost. And, having $25K+ machines sitting idle most of the time isn't a very good investment unless one has lots of cash sitting around. If I have complicated 3-d stuff, I just take it to the experts.
When I worked at a cellphone company circa 1998, the two guys in the model shop did AMAZING things with a Hurco knee-mill (no tool changer) and Unigraphics (now NX) software (before getting two new Matsuuras). . These were things like thin-walled compound cellphone housings, and even a 5th axis rotary table .
Unless you're going into production on something, seems the most flexible and cost-effective tools may be a BP type manual mill, lathe and maybe a CNC knee mill.
In all practicality, this is probably how I'll start out. I have a full time job now, and I'm not looking to quit it any time soon. I plan on working one off jobs, repair work, and mixing in gunsmithing. I'm hoping it turns from extra cash flow into a full time job, but that's all on me.

Like many others before me, I've had a desire to do this for some time now. I'm not quite sure what's stopped me so far (money is a big part). I've had a 20 year career in aviation so far, and I guess I'm ready to start the next adventure. My love for fabrication, and desire to work for myself, has finally pushed me this direction. I'm certainly keeping my eye out for good, used equipment. Problem there is that I don't have the keen eye to sniff out the garbage. I know how to check fit, form and function, but that's about it.

$40k is only the tip of the ice burgh. This type of work can take you from mild to wild in a hot minute. Just hoping to educate myself so I can get the most out of my money/investment.
 
sounds like you'd be a great candidate for one of those "I'm retiring and selling my whole shop" deals that crop up occasionally. I couldn't think of a better way of getting fully tooled up in one go if you have that kind of money to spend. It would be worth asking local gun clubs and the like in your area if they know of any gunsmiths getting out of the business. Might even get you some leads for future work too.
I'm definitely keeping an eye out for these types of situations. It's much cheaper to buy in bulk!
 








 
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