Andy's approach is what I had in mind. Additionally I also made sure that I
turned the outside to be concentric with the inside.
It's a very tight fit on the 14mm motor shaft. And a firm fit on the encoder
shaft. And still it wobbles.
So out comes the dial indicator with the encoder
Hi
The way I see the picture, you have quite a few microns of play only in
the roughness of the hole.
Using the screws that way amplifies the problem, as is pushes all the
error to one side.
I think the best option is to buy an elastic coupling. Ideally one that
fits both sizes, but just
It is not unusual for shaft mounted encoders to have some strain relief
rather than a hard connection. see link.
Reamers can be some fun stuff. I hand reamed the spindle on a 1913 Sears
Expert (made by South Bend, an "Old, reliable" manufacturer that was all of 4
years old back then) 14" metal lathe out to just over 3/4". The ends of the
spindle bore were just a hair over 3/4" but in between was smaller
Mine is a used BEI encoder I was given more than 10 years ago. Digikey lists
them at $800. For the sake of this Pi4 spindle testing I could just use the
servo Amp encoder outputs scaled down by the drive. Would be easier. Sent from
my Samsung S10
Original message From: Chris
Reamers don't work well in nominal size holes. So always leave enough meat ofr
it to do its work. The attached link gives good info on that topic.
Machine reamers cut on the leading edge only, there is no taper. Hand reamers
have a taper, and won't cut to a shoulder.
If concentricity is the
On Fri, 18 Jun 2021 at 16:52, John Dammeyer wrote:
> I'm thinking the better approach would be to drill all the way through
> undersize 3/8" and then drill half way with 13mm. Then only use the boring
> tool to bring the back half up to 3/8" and the front up to 14mm.
I would drill 8.5mm then
By total coincidence, I am doing the exact same thing. I just bought a 600
line optical encoder and now I'm attaching it directly to a motor. The
purpose is to write and debug some control software. In this case, I
REALLY DO WANT to run at the encoder's maximum rated speed of 5000 RPM, or
I think it is best to back up and look at the bigger picture. Solid
couplers are almost never the way to go. Or if you do use a solid couple
the motor or encoders needs to be mounted with rubber bushings.I
shouldn't be 100% solid.
Buy one of these, then bore of one of the holes for the
Sounds like a good plan. Hopefully the testing won't involve high rpms so
the od not being perfectly concentric will not matter. The motor bearings
will handle it but maybe the encoder bearings won't be as robust.
On Fri, Jun 18, 2021, 10:52 AM John Dammeyer wrote:
> This isn't as much a
The question about transformers was if the transformer could be placed
BETWEEN the VFD and the motor. Of course the VFD does not care if there
is a transformer between it and the utility power.
The problem being discussed here is that the motor wants 440 volts and only
220 is available. The
On 6/17/21 8:45 PM, Gregg Eshelman via Emc-users wrote:
Everything I've read on VFDs says do not feed them from a transformer.
WHY? Every VFD is being run from a transformer! What's
that thing up on a pole beside your house, or on a pad
behind your industrial shop? Yes, it is a
Transformers on the output are a bad idea but it's safe to run them on
the input. You just need to keep in mind that most inverters have a
pretty poor power factor so you need to up-rate your transformer to
suit. Two of my machines run 415V inverters on 240->415 single phase
step up
On Fri, 18 Jun 2021 at 06:33, Chris Albertson wrote:
>
> This is because any power transformer is almost certainly designed for 60Hz
> or possibly 50 Hz in Europe. If the VFD created a different frequency the
> transformer would not work well.
The input side is still at 50Hz even if the output
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