Concrete pad thickness for vertical milling center?

[MeUseDinoBone2Hammer]

In the planning phase of my garage demo + rebuild. Anyone know how thick of a pad I'd need to support a compact vertical mill? The size of mill I'm looking at would be similar to a Haas VF1, Haas MiniMill, Brother Speedio. I'm thinking I should probably do 8", is that overkill? Will 6" be enough? Any other aspects I need to consider (in terms of the concrete) besides thickness and making sure it's nice and level?

Already dealt with specing the door heights and electrical, wondering if I'm overlooking something else in terms of the physical aspects of my garage that will be hard/painful to deal with after it gets built.

 

[Stuart in MN]

I picked the Haas Mini Mill at random and looked up its weight, it's 4,000 lbs. Not much different than a car or pickup, so I don't think you need anything special. 4" is probably enough.

 

[Hank11]

It will be a big deal to make the floor stronger and more stable later on. If you think there is any chance of more or bigger machines take that into account now.

 

[WAS Jr]

I think all the machine makers and vendors can give you floor thickness and material information. I believe accuracy won’t be guaranteed if you don’t meet them, if you are buying new.
Bill S

 

[theoldwizard1]

6" with wire should be plenty strong. If you can, pour that area separate so that there is a seam.

 

[CapriMikeC]

I have a couple 4500 lb Dyna Mechtronics DM4400M VMCs in my attached garage since 2005. No issues with the weight.

Last summer, I got a Haas VF-4 in my steel building which has a 4" fiber reinforced slab.

 

[WNYflyer]

I think all the machine makers and vendors can give you floor thickness and material information. I believe accuracy won’t be guaranteed if you don’t meet them, if you are buying new.
Bill S

^^^^
For example,

https://www.haascnc.com/Community/pre-install-guide/Mills/VF-1.html

 

[matt_i]

Fadal VMC-15 sits on 4" of concrete and is doing great.

Imo, your best bet is to turn the rapids down and don't be whipping the head all over the place.

You do have to think about how its rigged...my machine is at max counterbalance for the forklift I move it with, so its essentially 2x the load being put into the front tires. That can find a weak spot in the concrete considerably faster than the machine will by itself.

Some other things to think about - how to support the machining head and also its counterbalance as it travels so it doesn't hammer itself to an early death...how to deal with the cat-track holding wires and hoses that goto the machining head as it can stick up over top of the enclosure and can't be moved unless power is connected, backup all machine parameters (photograph, etc) before disconnecting power, replace backup (memory) batteries while still under power and before you move it....

Some of how I place equipment has to do with how hard it is to move it later and how often I think I'm going to be moving it....iow I don't want the toughest rigging job to be the one that has to be done the most frequently.

 

[MushCreek]

When I had a machine shop, we rented cheap warehouse space with (barely) 4" floors. We had an 11,000 lb. Fadal. I was sure it would punch right through the floor, but it stayed level for the 6 years it was there. Still, I'd want properly reinforced 6".

 

[cvairwerks]

Haas states 6” of reinforced concrete and no joints under the machine.

Down in our machining area, most of the mills are on 18” or thicker concrete and you can feel the floors vibrate if someone is taking a heavy cut. I think the smallest machine down there now is a 25 hp horizontal.

 

[NUTTSGT]

Probably more important than the thickness is the proper prep and compaction before the concrete is poured.

That being said, the area where the vertical mill is going to sit, poured at 6" isn't going to cost you much more in the grand scheme of things. . . . Mostly, save you peace of mind since you're asking.

 

[NORTON'S SHOP]

Vibration is more of a factor concerning floor thickness. Sure, a 4" floor will support the machine. We have 10,000# machines sitting on 12" of concrete in the shop where I work.

 

[fastev]

We had to put a 15” 8000psi slab with a double layer of 1” rebar on 12” centers under our DMU 50. You can still feel it in the floor vibrate under heavy cuts.

 

[ItsNemo]

We had to put a 15” 8000psi slab with a double layer of 1” rebar on 12” centers under our DMU 50. You can still feel it in the floor vibrate under heavy cuts.

Would it even be possible to make it not vibrate? Like imagine you anchored to solid granite a mile deep into the earth, you literally have a million tons of solid rock as your base (or imagine any other absurd base you could dream up)....I can't think you wouldn't feel a vibration in close proximity still?

 

[mcbane]

Would it even be possible to make it not vibrate? Like imagine you anchored to solid granite a mile deep into the earth, you literally have a million tons of solid rock as your base (or imagine any other absurd base you could dream up)....I can't think you wouldn't feel a vibration in close proximity still?

The next time you hike in the mountains, bring a 5 lb hammer. And when you are standing on the mile thick granite, hit the granite with the hammer and then enjoy the vibrations in the granite.

More rigid materials such as steel, concrete, and granite are good at transmitting vibrations. Only really soft materials, like rubber, can reduce the amount of vibration being transmitted.

 

[marak]

FWIW: I would not use remesh in the slab, but would use rebar. If the slab cracks it will at least have a chance of staying in the same plane. In my shop I poured a 6" slab with a thickened edge (12" with a 45* fillet to reduce stress concentration) around each 'panel' of concrete, all tied together with rebar. The idea being that if the compaction wasn't perfect, no worries, the slab essentially has a perimeter grade beam to transfer the load to where the concrete is in good contact with well compacted base. Here is a picture just before pouring the first of three slabs. I wish you well with your project.

 

[humpty]

You do not "need" more than 4" for any of the minimills. We started at 6" for all CNC installs and went up as they got bigger, heavier, etc.

 

[rooster59]

Type of concrete mix ie 4500psi makes a difference as well

 

[fastev]

Would it even be possible to make it not vibrate? Like imagine you anchored to solid granite a mile deep into the earth, you literally have a million tons of solid rock as your base (or imagine any other absurd base you could dream up)....I can't think you wouldn't feel a vibration in close proximity still?

Couldn’t tell you. What I can say is that DMG Mori sent a tech out to set the anchors, which he hand carried in a Pelican case, and are giant vibration isolators. Never seen anything like it. I’ll get some pics one of these days.
They still insist on verifying level and plumb every 12 months to retain the warranty. I suppose that’s worth it on. $600k machine.

 

[ItsNemo]

Couldn’t tell you. What I can say is that DMG Mori sent a tech out to set the anchors, which he hand carried in a Pelican case, and are giant vibration isolators. Never seen anything like it. I’ll get some pics one of these days.
They still insist on verifying level and plumb every 12 months to retain the warranty. I suppose that’s worth it on. $600k machine.

That's just badass would love to see pics!

 

[Eric S.]

You don't having to worry too much about level. The machines have the ability to adjust for that. Make sure the base is good and 4" would be fine but the manufacturer recommends 6" so can't hurt. We have many machines sitting on about 5" of unreinforced concrete. The base isn't even anything special just compacted dirt.

 

[Eric S.]

Except for our Matsurra, we had to pour a three foot thick slab for it to sit on. Otherwise there would be warranty issues. HAAS never questioned the concrete but I suppose they would of we kept calling about chatter issues or something.

 

[LS1-IROC]

My Fadal is 4500lbs and has been sitting on 4" 1948 era concrete for a while now. No issues.

 

[JSGAuto]

We had to put a 15” 8000psi slab with a double layer of 1” rebar on 12” centers under our DMU 50. You can still feel it in the floor vibrate under heavy cuts.

DMU50......Thats a nice toy!

4" for a little VF1 is fine. Checking it often for level/racking...maybe ball-baring is going to be more important in the long run, then the thickness of the concrete.