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PostPosted: Tue Jan 01, 2013 9:04 am 
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Koa
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What kind of grease do you use on your CNC router ball screws? How often are you re-greasing?

***Updated for Tony!***** :?

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Last edited by Brad Way on Tue Jan 01, 2013 11:38 am, edited 1 time in total.

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PostPosted: Tue Jan 01, 2013 9:56 am 
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I thought this thread was about something else entirely.


Posted using letters to form words, sentences and thoughts.

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PostPosted: Wed Jan 02, 2013 3:04 pm 
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If the ballnuts on the Fadal weren't permanently lubricated then they were using the same lube as the ways: Shell Tonna 68 or Mobil Vacra #2. I use that stuff for -everything- : tapping, machining, throw it on anything that should be slippy. I highly recommend getting a pail of it.

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PostPosted: Wed Jan 02, 2013 4:26 pm 
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depends upon your machine. do your nuts have zerk fittings? then go with a synthetic grease like mobil 1. if you want oil then try vactra #2/iso68 or "medium way lube" (it's not a cutting fluid by any means btw, -buy the real thing for machining) keep in mind that if your lead screw and nut are exposed they will collect sawdust which will act like a sponge and soak up the carrier oil out of the grease and/or any way lube over time.

were it mine and the nuts had wiper seals, i'd go with a synthetic grease.


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PostPosted: Wed Jan 02, 2013 10:28 pm 
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Koa
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Thanks for the help. I have a gallon of Vactra 2 which I can easily use on the screws. For the ball nuts I have grease fittings so I probably wouldn't hurt to pack them with a grease. The Ball screws are sealed so I shouldn't have too much problems with dust collection.

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PostPosted: Thu Jan 03, 2013 11:56 am 
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why mix the oil with the grease?


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PostPosted: Thu Jan 03, 2013 12:18 pm 
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arie wrote:
why mix the oil with the grease?

Haven't you heard? It the cool new thing to do laughing6-hehe

Really I see no reason to mix them. Funny thing though, on my new haas vf1 they have switched to using grease in stead of the vactra #2 that the older machines use, but for some reason they still use oil (Mobil shc625) for the spindle. Makes no sense to me why they would want to have both but hey I'm no engineer idunno


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PostPosted: Thu Jan 03, 2013 3:18 pm 
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ZekeM wrote:
arie wrote:
why mix the oil with the grease?

Haven't you heard? It the cool new thing to do laughing6-hehe

Really I see no reason to mix them. Funny thing though, on my new haas vf1 they have switched to using grease in stead of the vactra #2 that the older machines use, but for some reason they still use oil (Mobil shc625) for the spindle. Makes no sense to me why they would want to have both but hey I'm no engineer idunno


at typical Haas spindle speeds 7,500/10,000/15,000/30,000 rpm, grease won't be able to move through the tight clearances of the bearings to lubricate them and will blow through the seals (among other things). also the spindle oil is filtered and re-circulated through the bearings to help remove heat in order to control spindle growth and reduce bearing failure.


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PostPosted: Thu Jan 03, 2013 3:42 pm 
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[clap] [clap] [clap]
Good answer!! That's why you get paid the big bucks

Makes sense. Still wish they would just use the oil for everything so I wouldn't have to mess with grease and oil.


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PostPosted: Thu Jan 03, 2013 6:39 pm 
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I guess my thought was to grease the bearings because they have grease fittings?!? I have heard that putting grease on the screws can cause problems.

Is greasing the bearings a bad idea?

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PostPosted: Thu Jan 03, 2013 7:15 pm 
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I wouldnt say its a bad idea. It just seems redundant when you could use one or the other. Ive never heard of problems with grease on ball screws. In fact on a bar feeder I have for a Lathe I have to manually grease the ballscrews. It isnt directly connected into the lubrication system of the lathe (which uses vactra 2) so i have to manually grease it up. The grease holds on better than the oil anyway. Dont get me wrong I like oil but it needs to be on an automatic system to dispense it or you will have to apply it with much more regularity than grease.


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PostPosted: Thu Jan 03, 2013 10:17 pm 
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ZekeM wrote:
I wouldnt say its a bad idea. It just seems redundant when you could use one or the other. Ive never heard of problems with grease on ball screws. In fact on a bar feeder I have for a Lathe I have to manually grease the ballscrews. It isnt directly connected into the lubrication system of the lathe (which uses vactra 2) so i have to manually grease it up. The grease holds on better than the oil anyway. Dont get me wrong I like oil but it needs to be on an automatic system to dispense it or you will have to apply it with much more regularity than grease.


Thanks!

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PostPosted: Thu Jan 03, 2013 10:39 pm 
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ZekeM wrote:
I wouldnt say its a bad idea.


I was the one who mentioned to Brad that grease on the screw caused me all sorts of troubles. When I first got my machine I put some grease in the nut and smeared the screw as well and it wouldn't run at all until I cleaned all the grease off e screw.

I also have to be careful when I re-grease the nut to clean any grease that ends up on the screw because if I don't, my motors will stall the instant a ball touches grease on the screw. It doesn't make sense to me that this would happen but it does.

I use grease in the nut and oil on the screw for that reason.

Mind you though, I have a stepper driven system and my experience might not apply to servo machines.

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PostPosted: Fri Jan 04, 2013 1:51 am 
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For the zerk fittings any general purpose lithium grease is fine.

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PostPosted: Fri Jan 04, 2013 7:24 am 
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Andy Birko wrote:

I was the one who mentioned to Brad that grease on the screw caused me all sorts of troubles. When I first got my machine I put some grease in the nut and smeared the screw as well and it wouldn't run at all until I cleaned all the grease off e screw.


That's very interesting. I've never heard of an issue like that. By saying it wouldn't run are you saying that it was overloading the drive motor? I guess I could see that as an issue if your motors are lightweight. All my machines are used for cutting metal so they have pretty heavy duty servo motors. With wood you wouldn't need all that power. So I guess if you have lighter duty motors oil would be a better choice.

I learn something new every day :)


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PostPosted: Fri Jan 04, 2013 10:39 am 
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ZekeM wrote:
By saying it wouldn't run are you saying that it was overloading the drive motor?


I have no idea what the heck was going on. I have 381 oz-inch steppers driven with a gecko G540, screw is 2510. If there was a little blob of grease in the ball channel the motor would stall as soon as the ballnut hit it. It sounds the same as a stepper that's accelerated too quickly and stalls. Once this happened I investigated and this is very common problem for stepper systems - ballscrews must be kept clean!

My procedure is to grease the ballnut maybe once twice a year and oil the screws (I'm just using motor oil at the moment) when they start to get loud. I worry that perhaps oil on the screw might be diluting the grease in the nut but just don't know enough to know if that's significant or not. Keeping the screws oiled also let's me up my acceleration and max speed.

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