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load meter to determine wheel condition

M. Roberts

Cast Iron
Joined
May 11, 2021
Hello all, TGIF.
Has anyone ever seen or rigged up a load meter to a surface grinder to monitor the condition of the wheel, or to determine when it needs to be trued and dressed?

Thanks,
Mark
 
My VFD probably reads current but I'd think the condition of the surface would be the first indicator of a problem and way more sensitive than power or current.
Thought it was common on Blanchards and creep-feed grinders ? Also common on nc mills that have mmmm mmmm mmm, forgot the term, speeds up feeds according to spindle load.

I better go get some caffeine in the system ...
 
If they do not have one I put an amp meter on all my grinder spindles. Very handy.
Sometimes I'll draw a line on the face with and erasable marker and tell the operator that if it touches the line the wheel needs a stick.
A must have if doing creep feed on a manual machine or you will cook the spindle.
My cncs have a programmable limit and will stop and put up and error if the current gets too high.
Also a mode where the feedrate is constantly changing based on spindle load. Another creep feed thing.

Trick on a old Blanchard where often the ampmeter not sensitive enough to see things easily. Double or triple the winds on the meters transformer coil.
Bob
 
Guys,

I definitely can see the need to have a load meter on a machine that is used for creep feed grinding. My Okamoto 1020EX machine has a load meter that had a limit built into it; if the load gets to "x", it will trip....it is never utilized. The larger Okamoto 1632 machine is not equipped with a load meter, I wish it did have one. There are just so many variables that would cause the load to increase, I think that a person would go nuts working it out....like picking the winning lottery numbers....

Mark
 
Hello all, TGIF.
Has anyone ever seen or rigged up a load meter to a surface grinder to monitor the condition of the wheel, or to determine when it needs to be trued and dressed?

Thanks,
Mark

Yes LFE Corporation (formerly of Waltham) used to manufacture custom Load Transducers for industrial surface grinders. They were used with a separate instrument such as an analog gauge.

Essentially a load watt meter.
 
Top of the line is a load meter and a acoustic sensor along with a computer and software to watch it.
A simple tiny microphone mounted on the spindle with a amplifier and speaker can tell you a lot.
Old version of this is a screwdriver against spindle and your ear. You get to hear small changes going on. It sort of sings to you.
Programming a computer to learn different songs is a bit of a pain. Humans so much better at this.

This also neat for touch off with the spindle running and far more accurate than spindle off method.
I've used a stethoscope at times.

Bad finish, chatter, screams and howl are way to far. All this says is scrap the part or hope you have a lot more stock to go and don't do this again.
Bob
 
All of the CNC grinders I've used or seen have had one. It is especially useful when using CBN plated wheels as we could see the load increasing and pull the wheel before the plating was fully stripped and junked the wheel. We had a max load limit set for each wheel which would stop the process before anything catastrophic happened.
 
I think it's probably common on creep feed grinders, not much use for a regular surface grinding operation unless maybe when using plated wheels like mentioned above, but I'd suspect there's a pretty solid visual and audible indication even there way before the load meter would give you much more useful info.

I could see a load meter probably being useful on a Blanchard grinder as well just to see what kind of load you're putting on a much more powerful motor that barely grunts when it's heavily loaded. The main use for me on large lathes was to make sure I wasn't overloading the drive motor for too long.
 
... not much use for a regular surface grinding operation unless maybe when using plated wheels like mentioned above, ....
Do not knock if you have not tried it.
Works on OD grinders in simple grind use also.
I do like acoustics as unlike a meter where you have to pay attention and look they talk to you even with a back turned to the machine.
Feedback of any kind is good.
The ear is amazing but get 6 to 8 grinders talking all at once..You know one upset or getting out but which one?
Thank the lord for microprocessors, FFTs and signal analysis both on load and sound. Is this weird or crazy tech now?
In the old days one listened and felt the machine or grinder. Again feedback. B-port people get that touch the machine gives back.
Manual grinders also give that in the handles. That feel or touch is power consumed.
Bob
 
Yes, I ran an amp meter on a Reid 6-18 manual electrochemical SG running carbide. I could pull about 5 amps with a full 1/2 metal wheel with an electrical construct bonding wheel..with a 3 HP pope spindle, Going past the arc space would rapidly get taken up, That amp meter would swing up, and the machine would begin to grind with the diamonds.

Grinding only with the arcI would get a black surface and a very high-grade surface finish.

Putting almost any ground edge under high magnification one finds fractures in the edge. They are not detectable with a fingernail and often not even with a knife-edge check. The electrochemical edge was near perfect

Likely someone could market such ground carbide inserts for aluminum machining.

An RPM monitor likely would be just as good. Wheel gets dull and RPMS slow.
 
Backwards from me … if the needle wasn't well into the red, the lathe wasn't working hard enough :)

That's all well and good until you burn up a motor. Gotta watch motor temp running heavy in the red too long. I sat at 150% load plenty of times. Motor took it just fine, but it made some unpleasant noises and probably lost some lifespan.
 
Do not knock if you have not tried it.
Works on OD grinders in simple grind use also.
I do like acoustics as unlike a meter where you have to pay attention and look they talk to you even with a back turned to the machine.
Feedback of any kind is good.
The ear is amazing but get 6 to 8 grinders talking all at once..You know one upset or getting out but which one?
Thank the lord for microprocessors, FFTs and signal analysis both on load and sound. Is this weird or crazy tech now?
In the old days one listened and felt the machine or grinder. Again feedback. B-port people get that touch the machine gives back.
Manual grinders also give that in the handles. That feel or touch is power consumed.
Bob

I have tried it, just never felt like I needed it. Then again I don't have 8 grinders running at once.
 








 
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