I am in the process of converting my PM833-TV to CNC. I have read a number of posts with complaints about the stock system not being able to control how much lube goes to various lubrication points and having excess oil leaking from the machine. I watched a Youtube by Franco (check out Franco CNC). His video was very informative and referenced a supplier on Ebay (Supercrown105).
After a number of email exchanges with the folks from Supercrown105 (they are extremely knowledgeable & helpful). They were able to assist in supplying all of the needed fittings, nylon tubing, manifold etc. I finalized the attached plan. Here is a how it works:
-The PM-833TV is equipped with JY-16 Hand Oil pump. It has two outputs. One output will be capped off.
-A 4mm nylon tube will run from the output of the JY-16 to an adjustable manifold (DB8A). This manifold has valves that control the flow of each of the outputs.
-Each output will have a check valve connected to it to ensure that there is no backflow. This should help minimize oil leaks.
-One of the outputs will connect via existing tubing to the Z-ways.
-One output will connect via existing tubing to the X/Y ways.
-Each of the remaining outputs will connect to the X, Y and Z ballscrew via 4mm nylon tubing with push to connect elbow fittings.
I have ordered all of the parts (fittings, tubing, check valves & manifold) from Supercrown105 at around $100.00. This setup should help minimize leaking and provide better control to how much lube goes to each point. I will keep you posted as I proceed with this project.
I am placing an order for these components now. I have to take the mill apart to put it into it’s new enclosure and while I am at, I am upgrading to double nut ball screws, so I though it would be best to do the lubrication update as well. Thank you for the schematic!
Edit: I may have misread the part numbers, but the compression fittings (PA4-15326) that were purchased separately from the manifold did not come with ferrules. Just wanted to make sure others did not forget to purchase those as the shipping is expensive.
Running oil lines to the ballnuts seems excessive for the speeds they will be operating at and might actually be detrimental to the life of the ballscrew when compared to grease.
This is from Hiwins Ballscews.pdf file. It states that when running oil for ballscrew lubrication that it needs to be oiled every 15 minutes instead of every 2-months when using a proper Lithium soap based grease.
I realize that greasing the ballscrews could be difficult due to accessibility but I would think a flexible zerk fitting relocation line would solve that problem. Then since all you have to oil are the ways, I would think you could just add some check valves to the stock oiler to stop the leaking and be done.
Hmm… I have never read that oil is detrimental to the life of the ball screw. I do agree that the oil takes more maintenance (i.e., you have to pump the one-shot oiler handle and pull the oil out of the flood coolant with a skimmer), but the PM-833TV comes with a one-shot oiler, and it is really is not a hassle to run a couple more oil lines.
Also, the photo you shared is for oil recirculation, which is perhaps, the best way to lubricate a screw as it also draws heat away from the nut. That system is too fancy (and expensive) for me…
Don’t get me wrong grease is great too, but in my opinion, there is no issue with the oil approach.
Let me clarify about oil possibly being detrimental. its the lack of oil that can be extremely detrimental to a ballscrew. like if you run long programs and walk away for like 6 hours. The ways would be fine but the ballscrews could be lacking. the oiler was designed for hand cranking, how much hand cranking can you do in a day? with cnc the ballscrew can potentially move the machine around way more than you ever could and speeds far exceeding what you could do by hand. it does this unmanned.
I have 20+ of real world cnc shop experience and have seen the lack of oil caused by human error on ball screws/bearing blocks make them completely useless. This happens when let says, the auto oiler runs empty or when someone forgets pump the oil-shot oiler every few hours of use. Humans make mistakes and sometimes machines run drier than they should. In places I have worked, I have gone away for vacation and come back to machines with dry bearings on more that one occasion. Grease is like a 2-3 month buffer.
The ways on the PM-833 have grooves that can hold oil for an entire “work day” of use where ballscrews would not appreciate that at all. I like OPs design and there is noting mechanically wrong with it, I’m just saying that the user error with oil is more likely than it is with grease.
This discussion of grease vs. oil is very interesting. My total experience is limited to converting the PM833 to CNC and modifying the oil system as per the above drawing. To date, I have finished milling only 9 parts on the mill. Each day I start the mill, I pump the lever one or twice and move the mill through the extents of each of the axis. My longest job ran for about three hours. When it was complete, I checked the ball screws and ways, and everything had a light layer of way oil coating it. The balls screws always seem to be swimming in oil. The only issue I have had so far is that if you move the axis quickly just after lubricating them, they spray the oil around the machine. I thought of using grease before I modified the one shot oil system but was not sure if the grease would get into the ball nut properly.
