Retrofitting 5 axis Willemin W400 with LinuxCNC

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06 Feb 2022 14:27 #234109 by chris@cnc

Next pair I have is this one: KOYO 7006C-5GM FG P5 “SUPER PRECISION”
I have not sorted out the numbers... a bit of a guess. I may buy another pair but I am right now thinking about putting it in the top...
It is not P4 it is P5. I have read that that may not be a showstopper...
 

P4 or P5 = precession class
P5 bearings are more precise in run out. Good choice for high revolution.
For graese is my favorite "Klüber NBU15 " "00040260221" 50g tube "www.ebay.it/itm/284022846197" You may need  2-3g each bearing, not to much. The bearing go broken as well, same as too little graese. 
More problem will be to adjust the preload of new bearings. Be careful and search for some information howto adjust. It's not an easy job. It's a waste of time and money when new bearings also die quickly.

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06 Feb 2022 17:56 #234135 by MrK

Hello, nice project, I have a question, I do not see any rings or seals to prevent the grease from coming out, on your 3D? the purple parts are steel and the bearings are in the right direction ?
 

All parts are in steel. What I read, enough grease should stay in place as long as the bearings has been runned in correctly.
The purple parts are the nuts used to keep the bearings in position. The purple part in the nose also creates a labyrint to keep chips out. I have been thinking about adding an "air purge" (is that the name?) to further protect the bearings but that will be a future project... The machine has an "air purge system" in place allready with several parts beeing fed with filtered air.

One thing that puzzles me a bit is the green part. That is a spacer that I am 99% sure is made from the outher race of a spindle bearing. There is a channel ground on one side next to a hole in the spindle body wall. Looks like some kind of oil port. Maybe a remnant from a time when our modern grease didn't exist.

/MrK
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06 Feb 2022 18:02 #234136 by MrK
Thanks for the link for grease. I would have bought that one if it wasn't for that I found and ordered the SKF kind I wrote about previously.

Regarding the preload that should not be a problem since these bearings are of the type "flush mount normal preload universal mounting". When the bearings are placed back to back the preload will be the same (normal) regardless off how much the nut is tensioned.

/MrK

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06 Feb 2022 18:25 - 06 Feb 2022 18:26 #234141 by MrK
Regarding ammount of grease...
I checked out SKF documentation since I will use SKF grease and the bearing is a standart type also made by skf.

So first the speed factor "A" shall be calculated. A factor "K" is then picked in a diagram and then the diameter of the bearing of that specific type has a "Gref" that is used to calculate the ammount of grease "G".

In my case it would be:
A = n x 0.5x(d+D) = 18000x0.5x(30+55) = 765 000   => K = 0.44
Gref = 1.7
G = K x Gref  = 0.44 x 1.7 = 0.75 cm^3

Density of grease = 0,86g/cm^3 
=>   0.64g grease per bearing.

 
Last edit: 06 Feb 2022 18:26 by MrK.

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07 Feb 2022 17:02 #234258 by OT-CNC

I have been thinking about adding an "air purge" (is that the name?) to further protect the bearings but that will be a future project... The machine has an "air purge system" in place allready with several parts beeing fed with filtered air.

One thing that puzzles me a bit is the green part. That is a spacer that I am 99% sure is made from the outher race of a spindle bearing. There is a channel ground on one side next to a hole in the spindle body wall. Looks like some kind of oil port. Maybe a remnant from a time when our modern grease didn't exist.

Do you still have the fitting that went into that port, what was hooked up to it? That should give an idea if it was just to introduce a slight amount of positive pressure to keep contaminats out. I'm guessing moisture got in there. Or is it for the tool change air purge? In which case I would not expect any real air volume to travel through the bearings as that would wash out the grease over time. look for another opening that leads into the bore?
How is the spindle cooled? The manual shows a 20-25l fluid spec for heat regulation of machining head. Is the cooling cavity in the head casting?
Any more info in the machine docs? 
 

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07 Feb 2022 18:08 #234266 by MrK

Do you still have the fitting that went into that port, what was hooked up to it?

I think you mean the hole going through the spindle body where the green part is. That hole is closed with an M5 set screw. I have no access to the machine at the moment but I think that hole is unaccessable when the spinlde is positioned in the "spindle mount".

That should give an idea if it was just to introduce a slight amount of positive pressure to keep contaminats out.

The hole in the spindle is not for air. The air system is not connected to the spindle. It is connected to one of the motors and to some encoders. What I was thinking about regarding future "air purge" was to add an acetal ring to the spindle nose somehow.

I'm guessing moisture got in there.

Well the hole was plugged with the set screw. But yes, rusty bearings. Except the bearings only the spacer "pipe" shows significant signs of rust on the od. I may leave it as it is or I will turn the OD down a little if I dare. 

Or is it for the tool change air purge?

There is a separate tool change air purge in place. It sits in the top of the spindle blowing air through the draw bar.

How is the spindle cooled? The manual shows a 20-25l fluid spec for heat regulation of machining head. Is the cooling cavity in the head casting?
Any more info in the machine docs? 

The machine has a warmer/coooler with a pump that pumps fluid through the spindle mount. The 4 plugs of the cooling channels are clearly visible in the picture below. I havent turnd that unit on yet... I have no idea if it is working. However hoses looks good, have probably been replaced some time.

 

I have full documentation of the head but it seems like it is for slightly different version. Can't find anything about the hole in the spindle.  Anyhow, I probably will just put the set screw back, rely on the grease lubrication and forget about it...

/MrK
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07 Feb 2022 20:00 #234282 by OT-CNC
I would just close the hole the way it was. 
For rust removal, I have used evoporust. That stuff works like magic. It will not change your part dimensionally, only eats the oxides. Key is to keep your part fully submerged or else it will eat away where it sticks out of the liquid. It may darken the steel a bit. I would not turn the od down. 

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07 Feb 2022 21:13 #234291 by jpg
Good evening, I found a diagram of spindle with oblique bearings + some other examples
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07 Feb 2022 21:36 #234293 by jpg
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08 Feb 2022 15:26 #234344 by Todd Zuercher
I'm pretty sure that P4 is more precise than P5. (P5 is considered standard precision and P4 is high precision.) 

Once you get it back together, be sure to break it in slowly with a long run in procedure, while closely monitoring bearing temperatures.  Start running it about 2000rpm or as slow as you can without over current/overheating your VFD.  Run it for about a half hour (or until bearing temps plateau and stablize), then stop and let it cool for 15min, then increase the RPM about 2000rpm and repeat holding that speed for a half hour, then resting for 15min, until you run it at the full rated rpm.  If at any point bearing temps start to get too high, stop let it cool to ambient temp and start over. If you can't get up to full speed without it overheating you will have to tear it apart and start over.  Now what temp would be considered too high will depend on a lot of things.  I had one that the manufacture said 180F was the limit, and that spindle got every bit of that hot on the run in.  I made some worried phone calls to the manufacturer, and they reassured me it would be fine.  Unfortunately that $14,000 9kw router spindle only lasted a little more than a year (about 3mo out of warrantee.)  (We switched to a different brand spindle after that debacle.)  Most google searches are showing 120-150F for the too hot limit, but it really depends on what the manufacturer recommends.

chris@cnc post=234109 userid=25067

MrK post=234058 userid=29291Next pair I have is this one: KOYO 7006C-5GM FG P5 “SUPER PRECISION”
I have not sorted out the numbers... a bit of a guess. I may buy another pair but I am right now thinking about putting it in the top...
It is not P4 it is P5. I have read that that may not be a showstopper...
 
P4 or P5 = precession class
P5 bearings are more precise in run out. Good choice for high revolution.
For graese is my favorite "Klüber NBU15 " "00040260221" 50g tube "
www.ebay.it/itm/284022846197" You may need  2-3g each bearing, not to much. The bearing go broken as well, same as too little graese. 
More problem will be to adjust the preload of new bearings. Be careful and search for some information howto adjust. It's not an easy job. It's a waste of time and money when new bearings also die quickly.



 

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