Stepper motors and linear scale closed loop setup?

12 Jan 2019 00:21 #124002 by Hakan
Another video, Fix the Y axis once and for all (I hope). Take the opportunity to install oiler hoses and limit switches. There is quite a bit of work condensed into half an hour.

13 Jan 2019 17:13 #124097 by OT-CNC
Some machines I took apart have a Z or multiple Z channels cut for oil grooves. This may distribute the way oil better than a slot. The slot is better than just a hole.
Also, are you planning on using some type of resistance fittings? Or some type of manifold with valving for oil delivery? The oil will take the path of least resistance if you just have open fittings. I may have missed that in your vid.
13 Jan 2019 19:19 #124100 by Hakan
At this point the problem is that there is oil everywhere :) It is leaking quite bad, bot slow.
The ways run smoother then they ever have, so oil is good.
Have not landed in the final solution yet. I have seen that least resistance
gets all the oil. The track I am now is to put pressure on each oil point individually.
I try to get inspiration from existing and commercial solutions. I'll have 15 oil points
4 for every slideway plus one for the ball screw, for each axis. 15 pumps are a lot to make
and I don't really like repetitive jobs, and the cost is x 15 for purchased parts.
I saw metering fittings, and ruled them out as non-functional. Perhaps they work with flow
but the flow here is next to nothing.
I just tested a pump today that can be used in a one-shot manner. Can most likely use it
for many oil points.

The machine is down for the moment though. A driver IC for a motor encoder has failed and
it takes a week to get a new driver IC.
13 Jan 2019 20:10 #124103 by OT-CNC
Bummer about the driver IC. I hate setbacks.

I have Bijur metering units on both my Bridgeport and Hardinge lathe. They work well as long as they are not "laquered" up from old way oil. The non continuous flow type have a check valve built in, metered output and filtration I believe. Search for the product pdf. They have a wealth of info regarding type, size, flow calculations etc in it. I don't know if they make it in your threaded hole m6? variety.
14 Jan 2019 11:26 #124149 by Hakan
It is a surface mounted quad differential line driver. Only two units are used so I'll see if I can bend some legs and do a temporary connection to one of the unused. Will save me a week. It sits on the back end of the motor so has nothing to do with the linear scales really.

I don't doubt that it works fine for you, and many others. But what I see is that the flow over the meter unit is determined by the pressure drop over the unit. And this only works if the major pressure drop is over the meter unit. I see from the small test with three oil points that one oil point is almost free open and there it would work. One point is basically closed and there it would not work since the major pressure drop would be over the oil point. Oil has to be forced in there over a longer time to end up where it should be. And the third is somewhere in between.

The line of thinking for the moment is to dispense a given volume to each point through an individual pump of some kind. I kind of like to tinker with this stuff.
14 Jan 2019 13:08 #124152 by andypugh

Hakan wrote: I don't doubt that it works fine for you, and many others. But what I see is that the flow over the meter unit is determined by the pressure drop over the unit.

Some single-point oiling systems have metering units that are a bit cleverer than that. When pressure is applied they fill a small internal volume with oil, then release that fixed volume when the pressure reduces.

I believe that some others are a simple restriction, though.
15 Jan 2019 09:10 #124229 by Hakan
That sounds like what i have in mind.

I mostly looked at the Single Line Resistance system. I am not dismissing the method as such but I think the oil points on my machine are not that similar or reliably made that the design rules can be applied everywhere. I might be wrong. Anyway I have made up my mind to make something myself. I like to tinker with such things.
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