VMC - Buy or Build? With Ramblings ;-)

[magicniner]

So to me, people need to start looking past all the eye candy sheet metal etc and pay attention to what they are truly buying with there "Starting from £16'950" lump of money, which in reality soon becomes £20K when they fall for few over priced extra's.

You've carried me to that point but having looked beyond it's all a bit dark, at this point the best option I can put together is a new Bed Mill with a custom head incorporating a decent spindle cartridge and 3-4hp motor with ball screws and servos and a decent motion controller, PC and software.
More ramblings welcome ;-)

[m_c]

That's just reminded me that Fadal's were weldments, and David Decaussin was making the UMC10 for a while, which was a welded steel.

[magicniner]

I can see a whole raft of time with the MIG, TIG and MMA sets in my near future ;-)

[JAZZCNC]

That's just reminded me that Fadal's were weldments, and David Decaussin was making the UMC10 for a while, which was a welded steel.

Exactly.!!. . . Weldment machine isn't beyond commited DIY builder. Steel is cheap and plasma/Waterjet cutting isn't that expensive. Out source some heat treatment/stress relief and grinding/machining services then you'll soon have strong base machine to start with. £15-20K gives you fare amount of room to play.

To be honest I'd even look towards EG or Concrete Fixed Gantry machine because could build a Very strong machine with larger cutting area in same footprint.

[m_c]

My big worry with welding that kind of thing, is accuracy, and finishing the mounting surfaces. Unless you do it so things bolt together, access to finishing surfaces is going to be a challenge.

I've often wondered if there would be much price difference between welding and casting. By the time you factor in materials, machining them, welding them, stress relieving them, and finishing them, would it be more expensive than a set of patterns, getting them cast, and chucking the casting outside for year or so before machining/finishing them?
Plus spec the right grade of cast, and you get inbuilt damping, without having to worry that you're building a big resonator.

There are certainly lots of options. It just comes down to time and cost, as to what one suits.


If in your research, you happen to come across a Fadal with it's clothes of, I'd be interested in seeing how they've done the main construction.

[magicniner]

would it be more expensive than a set of patterns, getting them cast, and chucking the casting outside for year or so before machining/finishing them?.

Pretty much yes, there is an element of "Time is Money" so I'm not really after a kit I can start to build in 18 months time or so, hence looking for a product and considering a conversion on a new Bed Mill or an adaptation of a second hand VMC.

[m_c]

Pretty much yes, there is an element of "Time is Money" so I'm not really after a kit I can start to build in 18 months time or so, hence looking for a product and considering a conversion on a new Bed Mill or an adaptation of a second hand VMC.

That was more just me rambling :)

How about something like this? - https://www.ebay.co.uk/itm/Cincinnat...R/162890979240
I'd want to know what exactly why it was non-running, but set of servos, new controller, and the basics are done. The hardest part is always the tool changer. Off course it depends just how much space you've got...

Attached are some plans that Dave Walsh (of BT15 spindle cartridge fame/saga) posted at some point.

And here's some notes I made about the UMC10 (IIRC I noted them down from his videos)-

6" x 6" x 1/2" wall thickness column
10" x 4" x 1/2" wall thickness base

6500rpm spindle = ~11000rpm motor speed
3hp spindle

table 1 1/2" x 8" crmo steel

[magicniner]

Yeah, keeping an eye on all the usual second hand outlets, I think that Cincinnati might be just a little big but I might just squeeze that in.

BT30 is my ideal/minimum tooling, 6500rpm max spindle speed is NBG, that might do as a minimum though, he must have been a Model Engineer! ;-)

[JAZZCNC]

These are general questions to everyone, not just you Magic.?

#1 What travels would consider ideal.? . . . In X, Y & Z
#2 What's more important to you Bed size or Travel.? (Consider often you'll see 3ft+ tables with one or two 6" vices taking up only 18" space.)
#3 What would prefer to use Vice or Fixture plate.?
#4 What material cutting ability is most important Steel or Aluminium.?
#5 What's an ideal footprint.
#6 Bench mounted or Freestanding..?
#7 Fully Enclosed or Open.?

[m_c]

#1 What travels would consider ideal.? . . . In X, Y & Z
X Probably a couple of feet. It's not that critical for me, as most of my parts are round, and those that aren't round aren't that big, but I wouldn't limit the X when it's relatively easy to make it longer.
Y Ideally minimum 250mm, possibly 300mm. This is where most small mills fail for me.
Z I'd want enough height so I can fit a decent (probably 8" or 12") 4th axis under it, so enough to probably get a good 400mm under the spindle nose, and still touch the table with a shortish tool
#2 What's more important to you Bed size or Travel.? (Consider often you'll see 3ft+ tables with one or two 6" vices taking up only 18" space.)
Neither really. As long as the bed has a bit room either end of travel, you work with what you've got.
#3 What would prefer to use Vice or Fixture plate.?
Both, although if I had the Z room, I'd probably get a Pierson pallet system, then mount what I need on pallets.
#4 What material cutting ability is most important Steel or Aluminium.?
Both for me. I need to hog lumps of steel down for repairing things, but most production bits are aluminium.
#5 What's an ideal footprint.
As compact as you can get the above with an enclosure, but still be able to overhang the table a bit when needed, or removable panels for the inevitable big bits (I do like the idea of the fixed table/sliding head setup used by Chiron, but it does complicate things)
#6 Bench mounted or Freestanding..?
Either as long it has a decent enclosure, and coolant tank.
#7 Fully Enclosed or Open.?
Enclosed. I've been soaked by coolant enough times to know enclosed is the only way.