Machine Balance/Rocking Due to Weight Shifting from the Table (Fadal VMC40)

Hi
Got a problem. I was using the 2216 workout program to finally get a program running on my "new to me" VMC 40. The issue: when the table reaches the left or right side forward most point of travel, the weight of just the empty table was enough to cause the rear of the machine to lighten enough to almost lift the rear off the steel bar stock the machine rests on. (sorry for the run-on sentence) I can move the table to the front (full -Y) left or right, put my body weight on the machine and lift the rear. The machine sits on two pieces of CRS barstock situated beneath the leveling screws. It's strange because that is where the factory leveling is done. The only thing I can think of is my concrete slab is sloping enough that the center of gravity for the machine is further forward than it should be. The machine faces the garage door and my driveway also slopes towards the road. I will have to put a level on the machine and/or floor to see if it slopes foward excessively. Haven't gotten the machine leveled yet, just an FYI. However, I wouldn't think the floor could be that unlevel for this to happen. Your thoughts?

NismoGT said:

Hi
Got a problem. I was using the 2216 workout program to finally get a program running on my "new to me" VMC 40. The issue: when the table reaches the left or right side forward most point of travel, the weight of just the empty table was enough to cause the rear of the machine to lighten enough to almost lift the rear off the steel bar stock the machine rests on. (sorry for the run-on sentence) I can move the table to the front (full -Y) left or right, put my body weight on the machine and lift the rear. The machine sits on two pieces of CRS barstock situated beneath the leveling screws. It's strange because that is where the factory leveling is done. The only thing I can think of is my concrete slab is sloping enough that the center of gravity for the machine is further forward than it should be. The machine faces the garage door and my driveway also slopes towards the road. I will have to put a level on the machine and/or floor to see if it slopes foward excessively. Haven't gotten the machine leveled yet, just an FYI. However, I wouldn't think the floor could be that unlevel for this to happen. Your thoughts?

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you should have individual pads for each leaving screw. I have fadls and never saw a bar used to level them. as you couldn't get a level machine that way.
you could have a 1" floor height difference and leveling off little 3x3 pads would keep you machine level, take the bars out and put pads underneath the screws then level it and your golden.

Delw said:

you should have individual pads for each leaving screw. I have fadls and never saw a bar used to level them. as you couldn't get a level machine that way.
you could have a 1" floor height difference and leveling off little 3x3 pads would keep you machine level, take the bars out and put pads underneath the screws then level it and your golden.

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What he said!! If you didn't receive pads and/or screws with the machine, here is one potential source:

https://www.fadalcnc.com/catalogsearch/result/?q=leveling+pads

My $0.02, machine table shouldn't even be moved, let alone exercised with warm-up program till machine is leveled.

Fred

The rocking you see has nothing to do with the machine, only shows the leveling screws aren't adjusted to carry the same weight. Actually one or two of them are doing nothing other than keeping it from rocking more than it is now.
Dan

Typically it is bad practice to let a machine sit for a long period with the leveling screws bearing grossly different loads. The bed casting may become twisted requiring opposite loading of the leveling screws to remove the twist and several future re-leveling jobs as the machine "settles" back in.

When I have leveled machines with "questionable" pasts, I have semi leveled them, let them sit a day or two, Re-level, then check again in a week, if any movement, recheck.

I have had machines (old machines, probably stored out of level) sit for well over a month, and still move slightly.

Delw said:

you should have individual pads for each leaving screw. I have fadls and never saw a bar used to level them. as you couldn't get a level machine that way.
you could have a 1" floor height difference and leveling off little 3x3 pads would keep you machine level, take the bars out and put pads underneath the screws then level it and your golden.

Click to expand...

I'm going to cut the bars into individual pads and put a divot in them with a 1/2" drill bit. I know the concrete pad is fairly flat but it most likely slopes towards the front of the machine as that is where the garage door is and the driveway also slopes to the street.

Vancbiker said:

Typically it is bad practice to let a machine sit for a long period with the leveling screws bearing grossly different loads. The bed casting may become twisted requiring opposite loading of the leveling screws to remove the twist and several future re-leveling jobs as the machine "settles" back in.

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It has not been sitting very long with the screws under different loads. For the most part, it has been sitting on straight on the concrete. I just now put in on the bars. I'll definitely balance the machine once a week for the next few weeks.

How many feet does this machine have? I thought some Fadals have 3 feet so they cannot rock. When aligning motors the first step is identifying the ‘soft’ foot and shimming that. Then you can tilt it fore and aft or left and right by putting equal shims on two feet. Machine leveling is similar.

NismoGT said:

.....I just now put in on the bars......

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On a concrete floor, it should sit on individual pads, not bars, unless the bars are really thin or grouted to the floor. Do you have a machinery level? If not you'll need to get one to do a decent job setting the machine up.

the fadal should have 4 leveling screws. I think my 40x20 has 4. my old 80" excel machine had 8
. dont make your pads too big 3x3 is fine even 2x2 is ok. to big and they wont sit flat for a few days. in all honesty the only reason the pads are there is to protect the concrete floor.

takes two people to level a machine fast, unless your creative and have 2 I phones then use face time on the level and watch the screen with the other phone. guy showed me this trick a bunch of years ago and man thats a time saver.
dont level off the table level off the y way's. 6 bolts pull slide cover back and put level on . I slide the y back as far as it will go.
then when your finished rapid the machine via a program on all axis for about 5-10 mins and check again.
that little machine will be fine and level up quick.

Vancbiker said:

Typically it is bad practice to let a machine sit for a long period with the leveling screws bearing grossly different loads. The bed casting may become twisted requiring opposite loading of the leveling screws to remove the twist and several future re-leveling jobs as the machine "settles" back in.

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most people will find that hard to believe, but ive seen it on a few big mills.

The grade your floor 'plane' occupies has little to do with requirement of machine leveling, and leveling includes that each footpad supports its portion of total weight - machine+tooling+workpiece. [ie] Of 8 pads each supports figuratively 1/8 the weight, in reality the central pads bear more load. If a #40 VMC might weigh 6,500lbs then 8 pads bear 800 pounds minimum each.
No other condition is satisfactory. It is also possible and occurring on a regular basis your concrete is of insufficient thickness for a proper machine foundation.
Your divot pads will help reduce pressure per square inch directly proportional to surface area CONTACT, not just their size. You'll do well making sure they engage to highest amount possible. Subsequent leveling should be recorded by date, amount and which pad/s until stability is attained. Mask perimeter where you put level, to alleviate one type of variance, condition of the surface. Amount is simply interpolated by screw pitch of levelers or measured by shim under a .0005 per foot bubble level. Sit it on a a decent bar of known length, or 1-2-3 blocks. If .005 shim centers the level on 12" spacing, the feet making the bubble center are 5' apart, one side is .025 low, maybe in X & Y axis. A rocking machine might be off 1/2"...
It's not done until table shows no deviation covering entire range of travel, including tests of Z up and down.
I've leveled countless machines. Doesn't matter; drill press, knee mill, Bullard or DeVlieg, stability and level are essential.
Not to insult, but I see a recommendation two men and I-phones are the trick. Meh. I don't know what increments an I-phone is calibrated to, but a 7" long toy isn't any better than a torpedo level.
I do it my self always, with shims under level/bar and knowing screw pitch there is no trick or double labor. A large machine, as in a long way around, maybe, with some intern to read the level if he knows which way is north.

Machined bed-ways as susceptible to miss-leveling as one running linear bearings. But leveling isn't just screw pads in the base. Something like the divot pads mentioned are a long ways toward stability, distributing small hardpoints to a greater surface area versus what is near certainly concrete of insufficient compressive strength or thickness.
FWIW the most demanding foundation requirements were made for jig boring and grinding machines, now CMM's get that attention.

For the best examples I can relate personally;
The line of DeVlieg Jig Bores denote size by spindle diameter, ie #4 is 4"Ø...The installation manual specifies that '4' signifies one more detail for utter dependability. A four foot thick concrete, isolated machine bed that quells any disturbance from adjacent equipment. Just one reason they are legendary when it comes to accuracy.

At the most prestigious local [or most anywhere] government contractor, they opted a very large and millions worth of 7[?] axis Swiss CNC mill, for a brand new building...naturally location and orientation preplanned. Despite chiding of mere Millwrights and Toolmakers they [architects and concrete contractor] pressed on. Well, they failed to provide bed as specified by the machine builder, barely averaged 18". Swiss techs came out and spent 10-odd days trying to get it zeroed to no avail. Finally they asked about the floor, and shocked when the discrepancy was revealed. Sure, Swiss techs are a touchy lot, but when millions [and reputation] are on the line who better to pay attention to? They left.
The mill was disconnected, moved far enough aside, tented snugly. More contractors came in to survey and core footings to bedrock, mixers with looong exhaust pipes [inside a completed structure] backfilled excavation with high comp concrete-epoxy voodoo, while work and general managers awaited curing and sampling of the 're-work'. Same Swiss techs returned and were done in something like 3 days.
Guess who's dimes? However many it takes in $250,000+.

Toolmaker51 said:

Not to insult, but I see a recommendation two men and I-phones are the trick. Meh. I don't know what increments an I-phone is calibrated to, but a 7" long toy isn't any better than a torpedo level.

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I think you miss understood what I was saying.
the i phone is just to view the bubble in the level. not using the i-phone as a LEVEL. I dont even think there is a level on a phone is there?
BTW 2 people are best one doing the screwing one doing the watching, makes old bones going up and down alot less fatigued

if you use the I-Phone to watch the level than 1 person is all thats needed cause he can be screwing while watching his phone at the same time.