Home |
Search |
Today's Posts |
|
Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
|
#1
Posted to rec.crafts.metalworking
|
|||
|
|||
Orthoganol balancing - twinwheel grinders
On Fri, 31 Jul 2009 13:39:44 -0700, "Bill Noble"
wrote: if you have a scope, and a strobe, and the speaker "accelerometer", then why not just "do it right" - make a paint mark on the wheel as an "index", synch the strobe to the rotational speed and synch the scope and see where the peak is WRT your accelerometer location and then just add weight at the one place where it is most effective? Things are not as simple as they may appear. There will be phase lag in the accelerometer (speaker with reference mass). In addition, the grinder on compliant mount is very probably operating well above resonance (as Jon noted) so the acceleration vector will very probably lag the location of the imbalance. Jim's method combines quadrature resolution of the error vector with trial -and- careful observation to make phase ambiguity irrelevant. No reference marker sensor needed, don't even need an o'scope. Brilliant! |
#2
Posted to rec.crafts.metalworking
|
|||
|
|||
Orthoganol balancing - twinwheel grinders
"Don Foreman" wrote in message ... On Fri, 31 Jul 2009 13:39:44 -0700, "Bill Noble" wrote: if you have a scope, and a strobe, and the speaker "accelerometer", then why not just "do it right" - make a paint mark on the wheel as an "index", synch the strobe to the rotational speed and synch the scope and see where the peak is WRT your accelerometer location and then just add weight at the one place where it is most effective? Things are not as simple as they may appear. There will be phase lag in the accelerometer (speaker with reference mass). In addition, the grinder on compliant mount is very probably operating well above resonance (as Jon noted) so the acceleration vector will very probably lag the location of the imbalance. Jim's method combines quadrature resolution of the error vector with trial -and- careful observation to make phase ambiguity irrelevant. No reference marker sensor needed, don't even need an o'scope. Brilliant! actually, I have sitting right in front of me a very old device called a "Davey Vibrometer" that is an entirely mechanical (well, it uses electrical power to light a light bulb) solution to this problem - it is basically a very sensitive "dial" indicator with a mirror and a beam of light. (if you can't resist having this, make me an offer I can't refuse - I don't actually collect tools, but this thing is cool and works) - you can find me via my web site, wbnoble.com I believe it was used for exactly this purpose (balancing), but I have never found anything to confirm that 100% |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Orthoganol balancing - twinwheel grinders | Metalworking | |||
Orthoganol balancing - twinwheel grinders | Metalworking | |||
die grinders | Metalworking | |||
Grinders | Metalworking | |||
grinders | Metalworking |