Encoder Installation on PM-25MV Mill

[nicolasjolliet]

Well, that’s a lot of interesting answers above. You guys are really fantastic on this forum. With all this help, I might be actually making chips one day! (if my spindles ever get delivered ).

When I read from the above replies:

"My guess is that the speed rating is a function of the electronics ability to read the pulses without missing any.”

"The question is what is hoped to be accomplished with the encoder at high RPM and if it's worth the cost.”

I want to rephrase my question:
Since one needs an encoder to mainly do taping at low rpm, one does not care for the encoder to be reliable at a high rpm.

Then by pushing a 3krpm encoder to a 6krpm milling operation, will I destroy the encoder? our simply get an unreliable reading? this needs to be clarified, I’ll email automationdirect as suggested above. From what you guys say, if the bearings don’t melt it should be ok?

If I don’t want to spend big on a fast encoder, and if I can’t push my standard encoder, would I have to remove/unplug it from the spindle every time I want to run my spindle at 8000rmp?

It would be a shame to limit the max spindle speed by half because of an encoder.

Now that looks very interesting:

"And then there are the component encoders like RLS makes that are mechanically limited only by your mounting choice. If your spindle is rated to 10K and you can mount the magnetic ring to it somehow, then you are golden.
https://www.rls.si/eng/products/rotary- ... ic-encoder”

Has anyone tried something like that?

I don’t understand this:

"make sure you don't exceed the electrical bandwidth of the encoder or the Acorn at 10K rpm.”

what is the electrical bandwidth of acorn?
a voltage in/out, current?
or some sort of “amount of data”/s? or an operating frequency like 200khz?

[martyscncgarage]

Its the encoder electronics reading reliably at high RPM on the encoder.
You should consider its mechanical ability at high RPM
Acorn spindle encoder can handle large count encoders no problem, but you don't need a high count encoder for a spindle. 1000cpr is adequate.

[tblough]

You'll see two speed ratings on encoders; mechanical usually in RPM, and electrical usually in MHz. Mechanical limits are based on the materials in the encoder. Will the glass disc wistand higher rpms without shattering, how long will the bearings last if pushed above their rated speed, will the bearings sling lubricant on the glass disc and obscure the grating, will the components get to hot at faster speeds and cause rubbing/binding? Those are the things YOU need to decide if you push it past what the manufacturer has tested at.

Electrical limits are based on how fast the internal electronics can handle the pulses generated. At higher rpms you could miss pulses and the encoder could report lower speeds or faster speeds, it could generate quadrature or differential errors, or it could actually fail. Those are things YOU need to test for and see how the control reacts in your machining environment when you push the encoder past the manufacturers specs.

If you are doing conversions for a living, this is probably not something you want to incur liability for. If it's a hobby, you might be willing to risk ruining a part, or having to replace encoders periodically. Your choice.

I've documented an RLS spindle encoder install here and I know of at least two others who have had goods results with them, and I've used Accu-Coder big bore encoders (1.875") on my lathe spindles with good results as well. Encoder and Acorn bandwidth has also been discussed on this forum.

You could have two reports, one with encoder configured, one without, and restore the appropiate one based on what you wanted to do. Without an encoder you loose feed per rev, wait for spindle at speed, actual rpm display, as well as rigid tapping.

[nicolasjolliet]

Thanks guys, I'll look for your rls encoder install.

[TCandee]

It took me some time but I reworked my encoder mounts on my lathe and mill taking everyone’s much appreciated concerns earlier in this thread. I already had all the concerns that were brought up but I made it anyway with the round belt and no lateral support on the encoder shaft to test it out.

Since then I had 3D printed several timin belt pulleys successfully and decided to completely redesign both encoder mounts using 3D printed timing belt pulleys, the pulley on the encoder side is independently supported and no lateral strain on the encoder.

Attached is the lathe mount. The pulley on the spindle shaft bonded to an aluminum core that I turned. The encoder side pulley is mounted on 2 bearings. The mill mount is currently printing and had a very similar concept.