PM-728vt design change request. Potential oil line failure.

[addertooth]

I have finally got around to figuring out how I am going to mount a DRO to my PM-728vt. This has meant a lot of crawling around the mill. I have been pretty pleased with what I have seen, once I started looking at the fabrication of the Mill in detail.

There has been one thing observed which is problematic. On the left hand side of the mill (under the table), a one-shot plastic oiler line bears against the lead screw which moves the X-Axis of the table. I ran my finger over the plastic oil tube, and discovered it was already getting a "flat spot" from the rubbing against the rotating lead screw. The table has been traversed a lot lately, to figure out DRO sensor placement, but still, the Mill only has a couple hours of use on the clock. (Mostly traversing back and forth to figure out DRO bracket placement.)

With a flat-spot already worn after such use, it points to eventual wear-through on this line with extended use, and will result in a lot of oil being dumped when the one-shot system is used. This could also result in precision surfaces not being properly lubricated (if the person is not alarmed by the increased pool of oil showing up in the tray). The one-shot system has a reputation for being "leaky", so I could see someone missing the early signs of a line failure.

As former Military, there was a common saying: "Don't come to me with a problem, unless you have the solution in your hip pocket". So let me propose a simple production fix. Move the oil manifold one inch to the left. This will keep the plastic hose from rubbing against the lead screw.

For the moment, I have an ugly fix for it. It will be replaced with something better after the DRO install is complete.

See pictures below.

 

[Tio Loco]

Thanks, I'll take a look at mine...

 

[koenbro]

Is your oiler leaking? Mine is and I will take some time figuring out where exactly.


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[rwm]

Me too.
R

 

[addertooth]

I have looked at the oil leaks briefly. I put a wadded paper towel under the pump, and no oil stains are forming on the top of the wad. It may just be the lubricated Ways dripping off excessive lubricant after cycling the pump. Other people have done the same test with a wad of paper towels and reported different results. I do have oil in my chip tray.

 

[rwm]

My oiler does not leak. But I am not super happy with it. It does not pump correctly unless the reservoir is darn near full. Do you guys have that issue? Is there a better replacement?
Robert

 

[addertooth]

My oiler does not leak. But I am not super happy with it. It does not pump correctly unless the reservoir is darn near full. Do you guys have that issue? Is there a better replacement?
Robert

My mill is too low on hours to have used much fluid, so I have not had the chance to experienced its behavior when lower on lubricant.
I really like the idea of the one-shot oiler, and it was one of the reasons why this mill was selected. I have had to run older mills, where the beginning of each work day was going around and lubricating the machine before the work begins. This feature seemed like a time saver.

 

[rwm]

Mine does not seem to interfere:

The line that goes up to the Z axis does not stay primed. It leaks down and fills with air. Anyone else? Is this a valve issue? I thought about adding a check valve on the outflow port.

Robert

Edit: Adder- it appears that your 3 way connector is mounted backwards. Can you flip it?
R

 

[addertooth]

Thanks RWM, it looks like you are right!
I may give this a shot.
I have no clue how this slipped past quality control, PM is normally pretty solid.

By the Way, is this a PM installed DRO, or did you do it yourself.

 

[RJSakowski]

I have finally got around to figuring out how I am going to mount a DRO to my PM-728vt. This has meant a lot of crawling around the mill. I have been pretty pleased with what I have seen, once I started looking at the fabrication of the Mill in detail.

There has been one thing observed which is problematic. On the left hand side of the mill (under the table), a one-shot plastic oiler line bears against the lead screw which moves the X-Axis of the table. I ran my finger over the plastic oil tube, and discovered it was already getting a "flat spot" from the rubbing against the rotating lead screw. The table has been traversed a lot lately, to figure out DRO sensor placement, but still, the Mill only has a couple hours of use on the clock. (Mostly traversing back and forth to figure out DRO bracket placement.)

With a flat-spot already worn after such use, it points to eventual wear-through on this line with extended use, and will result in a lot of oil being dumped when the one-shot system is used. This could also result in precision surfaces not being properly lubricated (if the person is not alarmed by the increased pool of oil showing up in the tray). The one-shot system has a reputation for being "leaky", so I could see someone missing the early signs of a line failure.

As former Military, there was a common saying: "Don't come to me with a problem, unless you have the solution in your hip pocket". So let me propose a simple production fix. Move the oil manifold one inch to the left. This will keep the plastic hose from rubbing against the lead screw.

For the moment, I have an ugly fix for it. It will be replaced with something better after the DRO install is complete.

See pictures below.

The solution is shown is Robert's post. Unscrew the two horizontal lines and loosen the vertical Remove the mounting screw and rotate the fitting 180º. Reconnect the lines.
Edit: I see that Robert covered that in his edit.