Problem with the belts

[andrejculk]

On the machine »Fadal 4020 VMC« there was constantly breaking the belt for the drive of the spindle, because the beltpulley of the engine and the beltpulley of the main spindle were not at the same hight; therefore the belts were not going on grooves. The belt also slipped lover many times for one notch on the beltpulley of the engine. For unknown reason the beltpulley of the engine was about 2.5 mm higher than the beltpulley on the spindle. That is why we removed the engine and pulled the beltpulley for 2.5 mm lover. Now, after another placing the beltpulley of the engine is at the same level as the beltpulley of the spindle. Belts are replaced, new. Because the beltpulley is displaced for 2.5 mm lower, I also had to displace the shield 2.5 mm lower of the engine. Belts now do not sit down on the shield (you can easily wheel round the spindle with your hand). Theoretically that should work but there is a problem, which we cannot solve. The belt which should be free/relaxed (it is not important if this is the 1st or the 2nd level), starts to pull by higher turns. You can hear loud noises (claping), which are the result of pushes of the belt. Is the problem in new belt, which are not »original fadal«?

I need the answer as soon please.

[andrejculk]

I was search on forum, but I dont found the answer. Was whoever similar problem with belts?

[carbidecraters]

Take the top cover off and look at both sides of the motor. The motor should be supported by a bracket and the bracket should be bolted to the Z casting using 2 motor mounts one on either side. If the motor mounts are bulging (They will show this in the back of the mount) then you need to replace the mounts. You can also check your tension cable and loosen. You may then run your spindle and push and pull the motor back and forth and if that stops your issue you should replace your motor mounts. It is possible to run your machine with the cable tensioner loose by not with a bunch of heavy cuts.

[JoBwan]

Originally Posted by andrejculk On the machine »Fadal 4020 VMC« there was constantly breaking the belt for the drive of the spindle, because the beltpulley of the engine and the beltpulley of the main spindle were not at the same hight; therefore the belts were not going on grooves. The belt also slipped lover many times for one notch on the beltpulley of the engine. For unknown reason the beltpulley of the engine was about 2.5 mm higher than the beltpulley on the spindle. That is why we removed the engine and pulled the beltpulley for 2.5 mm lover. Now, after another placing the beltpulley of the engine is at the same level as the beltpulley of the spindle. Belts are replaced, new. Because the beltpulley is displaced for 2.5 mm lower, I also had to displace the shield 2.5 mm lower of the engine. Is the problem in new belt, which are not »original fadal«?

Andrejculk,
Is this machine new to you or have you had it for some time? It does not make any sense that the belt pulley is higher on the motor, than the spindle pulley, unless at some point the machine stalled or crashed. This could have spun the spindle pulley and possibly moved it downward on the spindle shaft. I would not have lowered the motor pulley. Instead, I would have raised the spindle pulley (may have to heat it, it's a press fit) and re-aligned that pulley so that the tool changer (orientation) will work properly. Clean "and I mean clean" the idler pulleys for low and high gear, and make sure that the high and low idler cylinders are not restricted from full movement. The proper belt height should be centered on the idler pulleys. Put on a new set of belts and and should be good to go. If you have never worked on these machines, I would strongly recommend that you call in a fadal technician to do this. You don't want to mess this up any worse than it may be already!!

[carbidecraters]

A motor mount that is bulging and shot will raise the front of the pulley making it appear to be higher than the spindle pulley. We also had this problem and it sounded like a clapping/crunching sound. If you spray a little WD40 on the belt and the sound goes away for a couple seconds and returns then look to the motor mounts.

[JoBwan]

Carbide-
Good point on the mounts. I have never seen that myself. I only have 2 Fadals and both have been repaired due to a crash situation. I am the maintenace man, so "believe me"
I am taking notes. Thanks, for the tip!!

[andrejculk]

At first thanks a lot for the answer. So as I can see, the reason is in motor mounts. The problem is, that there is no FADAL service in vicinity and it is also very expensive. I will see tomorrow how the chiefs will decide.

[carbidecraters]

Andre check ebay USA for the mounts. Installation is easy if you can use a forklift to lift the motor up.

[andrejculk]

They ordered other belts now. I work current only in first gear, I removed belt for second gear. So are decided superior.

[HemiRoadRunner]

Have you checked the condition of the motor mounts? They are made of rubber, sandwiched between two rails of steel. When they wear, the motor sags. I've seen this problem many times before. One machine I worked on with this problem, caused the spindle pulley to get so hot, it slipped on the spindle shaft, causing incorrect spindle orientation. I'd replace the mounts asap.

[fatthead]

When i bought my 4020 new in 96, i had repeat belt problems. the tech swapped out my rubber mounts for solid motor mounts and the problem almost vanished. two years ago i started running only one belt on the Hi Range and i am problem free. for low RPM ranges (below 2500rpm) i type .2 that designates the hi range. example (S1200.2) and the RIDGED TAPPING FEATURE uses only hi range.

[andrejculk]

Originally Posted by fatthead When i bought my 4020 new in 96, i had repeat belt problems. the tech swapped out my rubber mounts for solid motor mounts and the problem almost vanished. two years ago i started running only one belt on the Hi Range and i am problem free. for low RPM ranges (below 2500rpm) i type .2 that designates the hi range. example (S1200.2) and the RIDGED TAPPING FEATURE uses only hi range.

Also i most probably will remove belt for first gear for now, and work only in second gear. (now was working only belt for first gear). what kind of is strength at low units? If be wanted to e.g. to make thread M24, is this after at all still possible, is strength tired? Or e.g. that I would be working with milling head with diameter 100 mm. This is most probably controversial after.