Garage Floor Weight Capacity

[mattthegamer463]

Hey guys,

I've been looking at mills on the classifieds, but I'm plagued with the typical issues like how will I get it home, move it, etc. And with only a 7.5 foot ceiling in the garage, height and top access is a concern. But a major issue I can try to get to the bottom of ahead of time is whether or not my garage floor can handle it. The last thing I need is buckling my house in half under the weight of a milling machine or large lathe.

My garage is below my house, which is a raised bungalow. 20.5 x 20.5 feet, a single piece of concrete with no relief cuts or anything. It might have rebar in it as one small spot has spawled a bit and some rusty colouring is showing, so I'm making a guess there must be some steel in there. Surface isn't looking great but it's alright as long as you aren't rolling anything around on cast iron wheels.

One thing I don't know is how thick it is, and I don't really know how I could find out. I could probably try to scoop the dirt out between the garage entry and the asphalt driveway and see if I can feel the bottom edge with a small hooked implement. Otherwise, don't know how I would judge it.

Does anyone have stories and experience with evaluating their place for heavy machines? I'd love to hear how anyone else went about it, and what the long-term results were.

Thanks gang

[Abaker]

Just don't drop it 2 or 3 feet like that guy with the big drill. Unless it's just a skim coat you should be ok with the floor. If you are really concerned then drill a small hole or two.

As for the low ceiling - as long as the mill fits it you are OK. A BP or clone is a tight fit but it works. You will have to rotate the head to pull the draw bar. Which you rarely need to do. You can find the exact dimensions of most mill online.

As a point of reference I have a 6.5 K lathe and 5k shaper on what is likely a 4 inch slab. No cracks, just pry bar marks

My ceiling is about the same height and the the BP is on 4X4s

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[Duffy]

Unless it was a REAL fly-by-night builder, your floor should be about 3 to 4 inches of concrete poured over granular fill, AKA gravel or crushed stone. THEY may have placed welded wire "temperature" steel in the pour, to resist cracking, and it mostly works. Personally, in your situation, I would have no concerns about the weight. BUT, if you will feel better, put some 2"X 4" pressure-treated as foot pads.Just remember, you are trading precious headroom for peace of mind.

[rkepler]

Remember that a garage floor should have been designed to handle the load of a car, and that's often 6000 pounds on 4 4x4 pads (essentially). So long as you don't exceed that you should be OK.

(The real problem usually comes in when moving the mill/lathe when you start applying point loads and a rolling load on an expansion joint. It's easy to fracture concrete some in those circumstances).

[lakeside53]

Assuming decent under-layment conditions, with pressure pads it's of no concern; even "ordinary" concrete mixed correctly is 3000 psi.

Most larger lathes have multiple "feet" and bearing pads for adjustment. My 5000lb 17x60 has 6 feet each with a 6 inch disk of cast iron to bear on. On my prior 400lb lathe, 8 feet each with a 6x6 x 1 inch steel bearing plate for the adjuster (shop made).

Mills typically sit on their base which spreads the laod, but you can put pads on if you want to level.

[Mcgyver]

In general, what a slab can handle is more dependent on what is underneath it; what the slab does is distribute the load.

I've also convinced myself its ok piggybacking on its design intent. If you think of the heaviest vehicle over the contact area of the tire, you're what upwards of 2000 lbs per tire? You can start to put some very heavy machines in there with 2000lbs per contact point (with a square of plate steel under the contact point).

My heaviest lathe is around 5100 lbs on six points - less point loading than an F350 loaded up. There's 20000 lbs of other machines and material and tool boxes and it hasn't tipped over yet.

[Cuttings]

I just had a thought while reading this. It happens to me once in while.
Could you put a steel plate down to slide the machine around on then remove it once you get it in place, or even leave it there to spread the load out.

[flylo]

I had a 10,000# lathe on 6 point & a 17,000# forklift end to end with a joint between them for 2 years & no problem.

[polaraligned]

If you have concrete, I would not sweat it. Just place the mill and enjoy it.

[mattthegamer463]

Well, that's a pretty unanimous response that its no big deal. The house is 38 years old so I'm assuming the floor is made with reasonable competence, and a 2000 lb mill hopefully won't be a problem. I'll probably be sticking with the mill/drill for a few more years until I really feel I deserve a proper mill but it's good to know I'll be alright.