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FP4NC Horizontal Spindle

TurboMachine

Plastic
Joined
Mar 14, 2013
Location
OH, USA
One of my FP4NC machines has a mechanical problem in either the horizontal spindle unit or the gearbox. I removed the spindle motor belt and tried turning the gearbox pulley by hand and it feels locked up. I wiggled the front of the horizontal spindle and it rotates left and right a few degrees, which is a lot more than the gearbox pulley does. Could it be one of the very many ball/roller bearings? Has anyone else had a similar experience or any advice? I don't want to just start tearing into this thing. It's a 3150 rpm with needle bearings on both spindles. Thank you.
 
Is the machine set for 0 speed when trying to turn it with the brake off. I can turn mine in any speed with the brake off from either the spindle or the motor pulley belt still on. What were the symptoms that caused you to remove the belt?

I sent you a pm yesterday

Andy
 
I pulled the belt because I believe the brake is on the spindle motor itself and it would allow me to feel the gearbox with more sensitivity.
 
Could be a bearing..sounds more to me that perhaps you have the gearbox with two gears selected at the same time..ie two different ratios
being selected have the box locked up....
The fact that you can move the spindle a bit suggests that it is not in the spindle.
If the issue was a bearing think you would have been given some warning...some noise before the failure/lock up.

Gear selection is via pancake gear motors that run the shift forks and their position is relayed to the control through cams and micro switches....
Bad switches or wiring or miss adjusted micro switch on a cam or two and you can have shifting issues.

Can you describe how you discovered this fault...was the machine doing a shift cycle or did you just turn it on and the main motor would not run the spindle....

At any rate i would look to the gear box first. Perhaps there is a shift fork with a broken pin or ????
There are no detents on the shift forks or rods ...everything is held via the gear motors...once the position is set via the cam and switch the motor stops and is held by the resistance of the
motors gear train...

Remove the cover off the shift motors (rear of the "Y" ram opposite the drive motor) and inspect the wiring and the position of the cams....Control should tell you what speed it thinks is selected. There is a logic tree in the orange book that shows the condition of all the micro switches for any selected speed.

Its possible to see the insides of the box if you remove the drive motor and drain the gearbox oil (rear section)
There is an access cover on the ram that can be removed and with some difficulty you can inspect the internals...however there will be an idler shaft between the view and the actual shift forks and sliding gears...

Opposite side can also be removed but its more involved and you can't see what the forks are doing once the side cover is removed..
Would not go there unless its a last resort.

Cheers Ross
 
I suggest you pull the horizontal quill and confirm that it still rotates smoothly. At least you can then rest a little easier that the problem is upstream in the transmission, which is "easier" to fix if a bearing went south.
 
I suggest you pull the horizontal quill and confirm that it still rotates smoothly. At least you can then rest a little easier that the problem is upstream in the transmission, which is "easier" to fix if a bearing went south.

Good suggestion, however pretty difficult if things won't rotate
To remove the spindle assembly you have to unbolt the keeper/drive ring that is between the horizontal input spline and the driving gears....To get access to the face Allens you need to rotate the shaft.

In reality you really don't need to remove the spindle, if you can remove the bolts from that coupling ring the spindle will be free from the drive/gearbox, and if its not damaged, it should turn free....
The trick. as stated above, will be getting to the face Allen's that likely will be shrouded by the splined shaft of the spindle.
Cheers Ross
 
I forgot about that ring of screws.

How jammed up is this thing? Sounds like it’s time to start disassembly. Maybe drain the oil and see if metal comes out.


Sent from my iPhone using Tapatalk
 
It's pretty jammed up. I will pull the spindle motor off tomorrow and get to the cover plate behind it. What is the proper way of draining the oil?
 
I think if you take the gearshift gearmotors off the cams, you can rotate the cams by hand. That might tell you something, such as whether it's in 2 gears at the same time or if one cam is bound up.
 
As to draining the oil:
On the FP4NC there are two gearbox reservoirs...The rear one is where most of the shifting takes place...The two are made so that the rear, feeds the front by spilling over
a cast in divider.
Pretty sure you can drain the rear sump without messing with the front...but just in case here are the details for both:

Rear sump is drained via a hex key plug in the bottom face of the "Y" slide between the dovetails....Got to remove or pull back the "Y" bellows in order to see it.
That is pretty straight forward and easy....

The front sump is another thing.....Here is the drill, or at least how i do this..
Guessing your machine has hand wheels. Move the "Y" slide forward till it hits the limit switch using power. Select hand feed , pull the hand wheel out and continue feeding forward
using the hand wheel, past the normal limit stop....you will reach the safety stop and the machine will immediately go to an E-stop condition and shut down....

Now if you look under the "Y" slide and just in front of the wiper on the vertical face of the "Z" column you will see another hex key plug, and it should be just clear of the wiper.....

Before you remove the plug, fabricate a drain trough....I made a simple one out of some scrap sheet aluminum.
Visualize a flat piece with the sides bent up at almost 90 degrees...the folded width of the piece fits between the box ways...there is a short section at one end where the bottom continues
for maybe an inch of less where there are no sides...sort of a tongue if you will....

Using duct tape i stick the tongue to the flat face of the "Z" ways between the boxes on each side....I place the tape up close to the top of the slide, i bend the tongue a bit so that mu little piece of sheet
hangs out and down like a shed roof.....
When you pull the plug the oil will run down the face of the "Z" ways and be deflected by the sheet metal out form the column enough so that it can be directed into an drain pan that you placed on top of the "X" axis....

Be sure to de-grease the face of the slide before applying the duct tape.....

One the oil is out and the plug replaced, you need to get the slide back into its normal operating range...With control power on (CRT lit) wind the hand wheel back to get the slide off the far limit switch and allow
clearing of your E-stop condition....

Cheers Ross
 
I think if you take the gearshift gearmotors off the cams, you can rotate the cams by hand. That might tell you something, such as whether it's in 2 gears at the same time or if one cam is bound up.
Would suggest doing this before anything else as its relatively simple/easy and doesn't make a mess. Take notes on where everything lines up/keys and make sure to put back together with the exact same timing, otherwise your gear shifting will not correspond to the spindle display.

I followed Ross' excellent instructions on the oil draining on my FP4NC a few months ago, but missed the detail about needing to hand crank past the limit. It took me a little while to figure out how to access the front screws. Would suggest plenty of towels on the top of the Z wiper area just in case your sheet metal funnel doesn't seal well. This would be a good time to change the wipers if necessary.

If you drain the transmission oil, be sure to check the passage connection between the front section and back section for sediment and clean if needed, so the oil can move back and forth from one chamber to the next during regular operation.
 
Just a thought! Instead of disassembly of the machine maybe its simply in back gear which is below 63rpm? I would reinstall the belt and see if it shifts to 0 rpm! But what do I know ? Don't get shift sequence out of order since it is not synchronized by removing shift motors with out marking them.
 
Pretty sure if the transmission is in a low gear the motor input shaft will still rotate pretty freely...Not so if turning from the spindle (output) side of course. I might have not read the OP original post correctly, but I believe he took the motor belt off and
tried to rotate the input pulley, and it won't turn...
Cheers Ross
 
One of my FP4NC machines has a mechanical problem in either the horizontal spindle unit or the gearbox. I removed the spindle motor belt and tried turning the gearbox pulley by hand and it feels locked up. I wiggled the front of the horizontal spindle and it rotates left and right a few degrees, which is a lot more than the gearbox pulley does. Could it be one of the very many ball/roller bearings? Has anyone else had a similar experience or any advice? I don't want to just start tearing into this thing. It's a 3150 rpm with needle bearings on both spindles. Thank you.


Turbo,
How did you first find out there was a problem? Was it a sudden lockup, or the spindle got tighter and tighter until it locked? What was the machine doing when it locked up? This will give clues as to whether this is a "can't find'em grind'em" gear shifting problem, or a grenaded bearing, for example.
Happy New Year,
RKlopp
 








 
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