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Hi The difference is that when a mass is supported in series between two springs, it is as if the springs are mounted in parallel. So if k=1 for each spring, then mounting between two springs, k=2. This was a surprise to me. So, I think it is likely that a rotor with 120 degrees symmetry has...

Hi I was planning on supporting a mass with 3 radially mounted springs with the mass in the centre. I assumed that the three springs would provide a constant k regardless of which 2D direction the mass moved. When I did the maths, my assumption was wrong. When pulling directly in line with a...

Hi I don't think so. They seem to be all there.

Hi By my calculations, a 300g weight suspended by 3 radially spaced springs, will require springs with a rate k of 0.005N/mm. I think I may need to make the springs I need.

Hi "You are trying to extract energy from the system. The easiest place to do that is where it is moving most. " Agreed but the scope can be rotated on the end of the arm about 270 degrees. That would require the TMD to be much more complex to design/make if it was mounted further out closer...

Hi The CoG is important only because the TMD is not acting through the CoG. I need to scale the TMD to account for that. The dominant source of resonance is from the torsion spring formed by the lower arm of the stand. Changing the relative direction of the upper arm is found to have no...

Hi The early images showed the plate laid on a towel so I didn't scratch the bench. The articulate arm was folded to allow me to keep the DTIs on the plate to provide a fixed reference plane unaffected by any movement of the plate on the towel (later anti-slip matting). The frequencies and...

electricpete I am trying to figure out why you went for the harmonic resonator in your presentation. I have never seen that type of device fitted to any rotating electrical machine. Why not just balance the motor and generator rotors? Just curious.

Hi electricpete I am going to be using the microscope on a working bench that is everything except rigid. Even if the microscope and stand were the most rigid a thing could be, I would still have a problem. Not sure what you mean by "resonant modeshape". Not a term I am familiar with...

For electricpete I had a look at your presentation. We are applying different methods. You are applying a spring and mass (tuned resonator) but no damping. I will be applying a spring, mass and damping explained here. I intend using magnetic eddy current damping demonstrated here

Hi Just for some clarification. This type of articulated lightweight arm is not an original idea. Here is a link to a commercial version. Link This looks as flexible as a soggy noddle with no obvious damping. Being sold under the Leica brand will add $$$ to the price. The arm I am using is...

Hi I see there is some discussion about the source and nature of the input noise. This is a microscope so in use, it is going to be knocked by the user, or the table may be bumped. At present the microscope wobbles for ages because the damping is close to zero. A bump is best represented by...

Hi I setup 2x dial indicator gauges to measure the deflection each side of an applied force. The DTIs were spaced at a measured distance. The difference between the measured deflections allowed me to identify the virtual point of rotation with some basic trig. The maximum deflection was...

Hi I measured the oscillation with a Gill Blade25 contactless position transducer. You can see it here The photograph of the go-kart throttle position sensor on this page is mine. The Gill Blade 25 was fixed. An activator, in the form of a light metal U, was mounted on the microscope. The...

On further thought, I could identify the pivot point by measuring k at a different location along the arm. The ratio of the difference between the measured k values would provide an estimate of the leverage and therefor the effective pivot...

Hi The microscope and adapter are the main mass. The stand arms do contribute, and I have included an estimate of that contribution to the modeled mass. I am thinking that simply shifting the mass away from the spring would be a reasonable model, as shown in the attached sketch. With this...

Hi I am designing a TMD for a microscope application. The microscope is mounted on a standard computer monitor stand. In effect, this is a weight on the end of a cantilever. The lower arm acts as a torsion spring. Unsurprisingly, this has flex and undamped harmonic motion that makes the...