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Oil pool under horizontal drawbar, Deckel FP2

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Diamond
Joined
Sep 25, 2011
Location
Garbsen, Germany
Deckel FP2 owners...

This is a new thread but not a new topic. It concerns the oil pool visible here

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this is below the horizontal drawbar on an FP2. A cross section drawing is here:

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Previous discussion of this oil pool can be found starting at the end of this post, and in the discussion that follows:

Making a slotting/shaper head cutter

I think I now understand the problem and also the solution, and wanted to run it by people here.

I think the problem is very simple: the cap at the back is leaking out the bottom because it is a poor fit. The amount of oil that leaks back along the shaft groove and around the shaft OD is minimal. But oil going through the rear bearing just leaks under that rear cover.

Solution 1: seal up the rear cover with some permatex or equivalent

Solution 2: in addition to above, replace the rear bearing with a rubber (RS) sealed bearing, from which the inside seal has been removed, but not the outside one.

I would be interested in any feedback about this. That pool of oil really bugs me. The oil in the speeds gearbox should stay there, where it belongs.

Cheers,
Bruce
 
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Your plan sounds like it should help.
The drawing you supplied is too small to really see, so i don't have a real idea of the actual setup, but i would include an additional item to your solution list,
I would investigate adding a drain drilling or groove to allow any collected oil just forward of the rear cover to drain back to the sump.
Further i would make a completely new rear cover and incorporate an "O" ring to seal it to the housing bore....

Cheers Ross
 
Hi Ross,

The drawing you supplied is too small to really see, so i don't have a real idea of the actual setup,

I am uploading images the same way that I have always done, but PM is now "resizing" them to be too small. Has anyone else seen this? Is there an easy solution?

I would include an additional item to your solution list,
I would investigate adding a drain drilling or groove to allow any collected oil just forward of the rear cover to drain back to the sump.

That makes sense. I'd try to make a hole which could be easily threaded (5mm, square on face) so if needed it could be sealed again with a grub screw.

Further i would make a completely new rear cover and incorporate an "O" ring to seal it to the housing bore.

I was also thinking along those lines. I can't understand why Deckel did not do it that way originally.

Cheers,
Bruce
 
Hi Ross,

I am uploading images the same way that I have always done, but PM is now "resizing" them to be too small. Has anyone else seen this? Is there an easy solution?

Bruce

Bruce:
Do you load your images to an album within your profile page, then link to that photo within your post?
That is how i have done since Photo Bucket changed their policy and tried to hold everyone for ransom...

At any rate posted some photos just yesterday and they came out full sized as usual....
Cheers Ross
 
Do you load your images to an album within your profile page, then link to that photo within your post?

Yes, that is exactly what I am doing, and what I have always done. But it does not work the same way for me now. I'll ask the IT people behind PM about this.

I'm adding a photo below that has nothing to do with this thread, but is intended to help debug the "small pictures" problem:

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Here is the exact same photo in a post from December 2017, where you can see it is much larger:
Studer RHU 450 from the 1960s

Cheers,
Bruce
 
This oil pool has been nagging at me, so I sent Franz Singer an email this morning with the photos, and just called him. What he said made me laugh. "The problem is that when the outside of the spindle is wet, oil runs down the shaft outside the drawbar and drips off. Your machine is too level. To fix the problem, tilt your machine slightly forward."

This is so simple that it's probably right. This weekend I'll lift it up and stick a pair of 6mm pads under the back.
 
This oil pool has been nagging at me, so I sent Franz Singer an email this morning with the photos, and just called him. What he said made me laugh. "The problem is that when the outside of the spindle is wet, oil runs down the shaft outside the drawbar and drips off. Your machine is too level. To fix the problem, tilt your machine slightly forward."

This is so simple that it's probably right. This weekend I'll lift it up and stick a pair of 6mm pads under the back.

That's too funny. In other news, I leveled my FP2 to within 0.0002"/10" yesterday - will have to keep an eye out for the oil spill now :).
 
Your machine is too level. To fix the problem, tilt your machine slightly forward."

Interesting, never had this problem on my FP2 or FP3. Guess i am not as careful setting mine up...Sometimes i guess its OK to be sloppy.
The NC's are setup the opposite..."leveled" with the front slightly high.....Understand it helps with lubrication and the draining of "tramp oil" as well as
coolant.

Cheers Ross
 
So, the oil pool comes from wrong design and the solution is to tilt the machine out of level to avoid, that oil comes out of the headstock?

Is a 0,6-mm-gap enough to let a hanging drop of oil drain back into the headstock?

Manni figured out that the oil is pressed out at high speeds (sentence above last picture in that post; the theme is mostly about painting a FP2 (with too glossy color)):
Stollmann rustet auf - Seite 16 - Zerspanungsbude

The cap at my FP2 has a rough surface (2 mm wall thickness), but it's contact surface (the outer peripheral area) is finished (ground?) and has a press fit. Not all areas of the finish reach the complete width of the peripheral area. Is it imaginable, that single machines have a cap, where rough areas remain in the finish that could result in a leaking cap?

Today I measured the gap (intersection area) between the key and the key slot: 0,65 x 8 mm (=0,025" x 5/16"); rename the attached file to "FP2_horizontal_oil_leak.png".

The key is riveted in one side of the gear (55 tooth). Only after pressing the bearings out, the gear can be unmounted. In the face of the gear (55 tooth) there are two M8-threads for pressing the bearings out (after removing the cap, the grub screws and the adjusting ring).
I think it's a good idea to renew the bearings for that gear (that transfers the force from the speed gear box to the milling head). These bearings (6010 - P6; Singer sells the higher precise 6010 - P5) run much under load and were worn out at my machine.
That can be done, when the horizontal spindle is removed for relubrication of the roller bearings (manual says once a year).

Cheers,
Karl
 

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  • FP2_horizontal_oil_leak.png.zip
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Manni figured out that the oil is pressed out at high speeds (sentence above last picture in the post):
Stollmann rustet auf - Seite 16 - Zerspanungsbude

The sentence seems to be asking a question. Could you post in Manni's thread, and ask if he figured out the answer?

Is it imaginable, that single machines have a cap, where rough areas remain in the finish that could result in a leaking cap?

The next time I have the headstock off, I will check. I'll also have a look at the rear gear bearings!
 
The sentence seems to be asking a question. Could you post in Manni's thread, and ask if he figured out the answer?
His german sentence translated to english language: "So, now I just have to find out why on the rear side at high rpm oil is pressed out between the headstock and the head."

I just asked in his Thread, if he found the cause.


The next time I have the headstock off, I will check. I'll also have a look at the rear gear bearings!
I can send you a rigid "tool" for holding the gear with two M8 screws while opening the ring under the cap.
 
The answers (rough translation) :
At Manni's FP2 the problem still exists at speeds above 1000 rpm, although the cap is mounted with sealant.
At his machine the oil comes out of the guiding way (dovetail guide) that's on top of the headstock [a long-reach head is mounted on the headstock]. Manni suspects, that that guiding way could be worn out.


My conclusion:
Obviously there are different ways for the oil to build a pool under the horizontal drawbar:
a) from top of the headstock out of the dovetail
b) out of the groove in the horizontal spindle
c) non proper sealed cap (less plausible because it's a press fit)

Two ideas:
The key can be dimensioned to decrease the gap between key and slot.
The black metal sheet inside the headstock can get a shape, that allows the oil to flow away faster.

Cheers,
Karl
 
I'm actually quite interested in this thread because I've wondered about oil seepage in the past that I've seen on a few other machines. Interestingly, my FP2 has been dry as a bone in that area since I got it. Fingers crossed that it remains so.... And yes, there is oil in there! LOL
 
I can now close this thread in a good way: I have found the cause of the leak and fixed it.

First off, the leak was (at least partly) due to damage in the end cap, but might also be from poor design. This cap must have been pulled by a previous owner who wanted to get to the two 6010 ball bearings that support the back gear. Here is what it looked like (the damage is not from me):

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No surprise that this was leaking oil. I think even without the dings and damage it's not a good solution to make an oil-tight seal. Here is my solution:

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This is made from plastic, with a 77mm ID 80mm OD O-ring for sealing. It has two M6 screw holes that can be used to push it out (screws bear on the retaining nut for the shaft behind it) which are blocked with grub screws in normal use. Here is a dimensioned drawing: it takes very little time to turn one, especially if you make it from plastic.

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I have checked both with and without the long reach head in place, and there is no more oil pooling behind the headstock any more.
 
Looking at the new cover Bruce constructed, thought some might find a little "back yard" engineering of value here.
There are charts and calculations for setting the depth of an "O" ring groove in a static sealing setup like Bruce shows.

In reality you can boil it down to the 10% rule.
Measure the "O" ring section height being careful not to compress it when making the measurement . (Note inch standard "O" rings are larger in height than their stated section size , and metric section
rings will be pretty much as called)

Make your groove the height of the "O" ring less 10%. So a 3mm ring would have a groove depth of 2.7mm.....
Cheers Ross
 
Hi Ross,

That's a useful tip. When making the cover I first looked at the table here:

O-Ring Nuttiefe t | O-Ring Nutbreite b | Radialer und axialer O-Ring Einbau

which showed that my O-ring (1.5mm cross-section diameter) should be compressed to a thickness of 1.1mm, corresponding to a slot ID of 77.8mm. I first made the slot that depth, but I couldn't even get the cover started pushing with two hands -- it felt too tight. I reduced the groove ID to 77.6mm and it got started but I still didn't like the feel. So I took the groove ID down to 77.5mm, which corresponds to compressing the cross section of the O-ring from 1.5mm to 1.25mm (16%, a bit more than your 10% rule of thumb). While it started OK, hand pressure wasn't quite enough to get it in, but a couple of gentle hammer taps and it seated nicely.

Since my cover is plastic, it may also have deformed slightly under pressure, making the O-ring compression less than 16% and closer to your 10% value.

Anyway, it works, and my 4 Euro Amazon purchase provided 5 O-rings, so I have 4 spares in case the first one hardens or takes a set and stops sealing.

Cheers,
Bruce
 
Looking at the new cover Bruce constructed, thought some might find a little "back yard" engineering of value here.
There are charts and calculations for setting the depth of an "O" ring groove in a static sealing setup like Bruce shows.

In reality you can boil it down to the 10% rule.
Measure the "O" ring section height being careful not to compress it when making the measurement . (Note inch standard "O" rings are larger in height than their stated section size , and metric section
rings will be pretty much as called)

Make your groove the height of the "O" ring less 10%. So a 3mm ring would have a groove depth of 2.7mm.....
Cheers Ross

Many thanks for this, this is really useful, I'll note it down somewhere...
 








 
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