New mill, anchor to floor or just sit it down ??

[Mr.Miz]

so I asked this on an old post today and was helpfully lead here. My question is why under the mill foot? Why not design something that goes over the foot and basically pulls up to get it into level. I realize the back side of the foot would have to be more creative but at least you wouldn't have to lift it up and then set it back down on something? So basically just take the picture and flip it.

 

[Gaffer]

Now I understand your question. The difficulty would be attaching the bar to the base. The other issue could be with the mill's weight distribution on the studs/hardware. I'm no engineer and am just taking a stab at it, but having the bar under the base seems like a stronger setup. I am curious about what the others have to say.

 

[Iceberg86300]

Now I understand your question. The difficulty would be attaching the bar to the base. The other issue could be with the mill's weight distribution on the studs/hardware. I'm no engineer and am just taking a stab at it, but having the bar under the base seems like a stronger setup. I am curious about what the others have to say.

If, and it's a very big if, the bar is solidly attached to the machine, strength would be equal.

Apologies for the horrid sketch. Still trying to figure out this Samsung note thing.

It's just a very basic diagram of the shear & moment you'd find in a bar subjected to point loads only.

Notice that the portion under the machine is subjected to a constant moment load only. If you cut that section out (which is basically what we'd be doing here) you can't just toss the moment, there needs to be a reaction somewhere & in this case it needs to go from the bar to the machine.

I could do the calcs for how much force that bolt going through the machine would be under but my gut feeling is that there's no freaking way I'd ever use such an arrangement. Plus the angles involved would add more issues depending on the feet used.

Welding and/or drilling would be required & I wouldn't want to come close to doing either. LOL.

But, it could still be done. I just think what's already been shown is a much more practical method.

Sent from my SM-N975U using Tapatalk

 

[Flyinfool]

I guess the best way to go would depend on the overall construction of your machine. My mill would not allow a bar over the top as the column is in the way on the back side. Also most machines have a flat bottom under the mounting points, Machines with a cast base will not be flat on the top of the mounting points.

 

[akjeff]

I don't see that the stress on the bar would be much different if were on or under the mill, but the load on the heads of the bolts holding it in place would be considerably higher with the bar bolted on the top as opposed to the bottom. With the bar under the mill, the bolts are basically just locating the bar in place, and the weight of the mill is almost entirely supported by the bar and the leveling feet. Though there would be a small load on the bolts due to the bar inevitably flexing at least to some degree, and would pull down on the bolt.

With the bar bolted on top of the base, the entire weight of the mill is essentially hanging from the heads of those four bolts. Not a good situation IMHO.

After typing this, I see Iceberg has already covered it, and did a much better job of it too!

 

[schmidty13]

...I settle my mill to as close to level that I can measure on my precision level... I've always been leery that they'd compress and I'd need to re-level.

I saw a discussion once, I think at the PM forum, about whether mills need to be level to the world, or if table/head alignment is all that matters. One guy made a comment that settled it for many, including me: "Tell Navy machinists that machines need to be level."

 

[akjeff]

I saw a discussion once, I think at the PM forum, about whether mills need to be level to the world, or if table/head alignment is all that matters. One guy made a comment that settled it for many, including me: "Tell Navy machinists that machines need to be level."

While I agree there is no functional need to level a mill, my shop floor has a pretty pronounced slope from the walls inwards and towards the garage door for drainage. The height difference between the rear feet and the front of my mill is around 3/4". Having my mill ( or any machine for that matter ) that far out of level would just drive me batshit crazy! When I set something round on the table/stand something on end; I don't want it rolling off or falling over. Just a plain good shop practice to level it IMO.

 

[schmidty13]

While I agree there is no functional need to level a mill, my shop floor has a pretty pronounced slope from the walls inwards and towards the garage door for drainage. The height difference between the rear feet and the front of my mill is around 3/4". Having my mill ( or any machine for that matter ) that far out of level would just drive me batshit crazy! When I set something round on the table/stand something on end; I don't want it rolling off or falling over. Just a plain good shop practice to level it IMO.

Oh for sure, I don't want to set an endmill on the table and watch it hit 30mph before shooting off the edge. I'm just saying that worrying about it being tenths of a degree from level is far down on my list of concerns in the shop. YMMV

 

[Illinoyance]

My BP is just sitting on the floor. I have used a bar to adjust its position several times. Couldn't do that id it were nailed down. I do need to shim one side to keep it from rocking. A level machine can be a convenience if you use a level or angle box during setup.

 

[akjeff]

Oh for sure, I don't want to set an endmill on the table and watch it hit 30mph before shooting off the edge. I'm just saying that worrying about it being tenths of a degree from level is far down on my list of concerns in the shop. YMMV

Same here, I just used a carpenters level on mine. With the change in seasons, I'm sure the movement of my slab would throw off a precision level job.