Welding of pads to base for soft foot correction

[svkd]

Guys,
During leveling adjustment of one motor we found difficulty to obtain acceptable motor’s soft foot(less than 0.05mm)we are getting 0.2mm soft foot due to in flat base support. The contractor/Vendor recommended Welding of pads(5-6mm thickness) to base for soft foot correction(see attached photo) . Is it acceptable solution for elimination of soft foot?

 

[kingnero]

Just to make sure I understand correctly:
You (or the vendor) wants to weld pads on the mounting base, and not of the feet of the motor itself?

Is the base not stable enough by itself? because even with all the padding you might install, you will still need to perform finetuning the alignment.
How do you make perform the alignment? by inserting shims under the feet?

 

[Artisi]

Welding pads onto the baseplate doesn't correct soft foot. The correct procedure is probably to remove the motor and the driven component and install the baseplate without any bowing, hoging, or twist. Pack and shim under the baseplate to put the upper mounting points into acceptable position and then offer the driven unit and the motor onto the baseplate and align the 2 units relative to each other.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[svkd]

kingnero vendor wants to weld pads on the mounting base, after welding the pads his plan is to perform alignment by shims

 

[Tmoose]

Hi SVKD,

Is that picture your actual installation?

So some of the pads will be welded to the base with the intent of having the top surface horizontal, which the handsome stamped base's top surface is NOT ? Will there be shims under the welded plates to set them level?

 

[svkd]

Tmoose , the thick shim(6 mm) will be welded to the mounting base and then plan is to perform alignment by putting shims on top this welded pad as needed.

My question is acceptable solution for soft foot elimination??

 

[byrdj]

personally, I would say NO.

and if not done with proper consideration make things worse. do they plan to just edge weld or drill holes and have welds on the inside. will there be a post "in place" grinding to restore flatness

my "guess" is that the thick shim is not flat. having them ground would be a solution and then spot hone the base plates to achieve the best blue contact (>70%) with a KNOWN flat plate.

there was a recent post concerning the number of thin shims that should be used due to the accumulation of flatness tolerance and resulting soft foot.

 

[svkd]

byrdj , they plan to just edge weld the thick shim as shown the attached picture. What do you think drill holes and have welds on the inside is better solution??

 

[byrdj]

I took a second look at the photo just to see IF I could determine what size of motor this effort is for. the thing I THINK I see is that there was no designed provision for the motor base and that it appears to just be sitting on a structrual metal frame.

One can not see the total installation and thus making comments on design and corrections without knowing is not good. I once got drug into a problem with a large motor installation that used I beams to mount the driver and driven. cutting to the jeast of a very long story the problem was the unlevel/poor support of the beams on the factory floor and the lack of a desinated mounting base. (sort of what I think I see in the photo)

while I fear making any more comments due to lack of total information, maybe the structrual frame does need to have design base plates installed by through welding including multiple internal locations THEN the four base plates will need to be surfaced ground to restore/ensure their flatness and parerrelism with the driver/driven center line.