What's new
What's new

Oil circulation pump for open bearing spindle

It's a function on the bearing size and type and the RPM's expected to run at. Off the top of my head, I do not remember the calculations involved calculating this. It's been over 45 years since I did this one hookup. Bijur provided a engineering manual that had all of the information in it and the calculations involved. This wasn't in the old "yellow" manual the they usually provided. It was in a "light blue" manual. I'm not too sure i still have a copy of it now days. Anyways, you're dealing with "X" numbers of CC's per minute of oil flow. If you're dealing with a circulating style pump, you use control units or metering units meant for continuous flow. Yes, there is a difference in the Bijur style metering units out there.
I would look around on the Bijur website and there should be a section on "engineering information" I would start there, if such a thing exists on their website. May have to contact them. I wish I could help more, this about it.
Will say, the amount of oil flow will be shockingly way less than you expect that will be needed.
The bearings are 6212 R4 and 6209 R4.

I put in a request with Bijur to get their opinion on what to do, they sent it into their design people.

Yeah I agree it should be a pretty small amount of oil.
By using a adjustable needle valve you can adjust the flow into a catch can before you put it into operation.That way you wont need a sight glass(they don't work up hill for drops per min)and you wont have to guess about meter sizes. The cycle time on the smaller piston pumps , I think is 5 min(fastest) and just about all that time is spent on the intake stroke at which time there is no out put. So even if you don't use a full stroke out put in 5 min as soon as the cam starts to lift the piston the pressure / flow will stop. So adding an accumulator will store enough oil under pressure until the next pulse giving a steady constant flow. It doesn't have to be anything more than piece of pipe/tubing with an air space; the pump has an out put check to stop any back flow.

The advantage to a piston cyclic pump is cost and no heat generated by the pump.
Awesome, appreciate that, it's very similar to what the tech at Bijur suggested also. Thinking of a surefire pump which I believe is able to be programmed to cycle on and off.

Sounds like best approach to have the needle valve close to the unit, run high pressure line to the valve and allow the pump to pressurize the line then bleed down while it drips into the unit.

Needle valve on the return also so that it can be timed to retain the desired volume of oil in the spindle bearing bath.
Don't let the bearings run in a bath of oil. That can create excessive heat that will draw oil from the bearings. I disagree with a needle valve on the return end IMO. Ken
Getting back to this, I ended up getting that Surefire PDI pump. It's a neat unit and in speaking with Bijur they also felt it was a good choice for this purpose.

Getting my head around the rest of the details involved, currently. So far I plan to set this up similarly to how it's used as a replacement for a manual pump with an injector installed into the outlet and then plumbed in normally after that.

They have a kit that allows it to be used like this for milling machines, but being that I need a lot less flow per cycle (but more cycles) I am selecting a different injector, which of course has a different thread.

The pump outlet is 1/4 BSPP, the injector is 8mm but inlet and outlet. The current tubing is 7mm, so I'm going to change that to more common 6mm FEP tubing.

Bijur is 4 weeks on pretty much everything, so I bought some new old stock ZEM injectors to try.