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About Mike_Danielson

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  • Birthday 10/22/1942

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    Materials scientist--PhD

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  1. Mike_Danielson

    Houshold LED lights than don't strobe? Does anybody know of any?

    If you look at youtube, you can find a number of autopsies of various LED bulbs that have failed. They all seem to have a full wave rectifier with some filtering and voltage control. The large filter capacitor is considered the weak link, and when it goes out, there will be an increase in flicker. I found one engineer that measured the ripple on one particular LED bulb, and it was very low--maybe 30 mV on top of the DC--this is really small. LED behavior varies among the manufacturers because quality of the power supply is all over the place. Placing a battery in parallel with the power supply and bulbs should help to buffer out the voltage fluctuations when a AC to DC power supply is used. Mike D
  2. Mike_Danielson

    Houshold LED lights than don't strobe? Does anybody know of any?

    I looked up the A19 soraa lights (as you recommended) and something does not look right. Percent flicker is less than 30%--what does that mean? Why not 0% flicker which a DC powered bulb would provide? If flicker triggers some health problem, can you trust a bulb that has approximately 30%? The color temperature is 2700K and they give it a CRI of 95--this seems impossible. I would not trust these for work with varnish. You need 6500K for good color rendering. I do not have a dog in this fight. Mike D
  3. Mike_Danielson

    Houshold LED lights than don't strobe? Does anybody know of any?

    Hold on about the Soraa LED lights. The MR16 are supposed to be flicker-free. They require 12 volts AC; so, you will have to provide a stepdown transformer, and a special connector. MR16 appear to be flood lights; suggested use appears to be restaurants. Color temperature is too low to get a correct color rendering for varnishing or matching. The lowest is 2700K. Cost is about $20/bulb. You just as well go with the 12 volt DC bulbs that the campers use since you will have to provide a power supply in any case. These bulbs seem to be widely available. I have not checked on the color temperature of the DC bulbs which might be an issue. They look to be more conventional in shape (not floods), use the Edison base, and are cheaper. Mike D
  4. Mike_Danielson

    Oil varnish sweating

    In examining your pictures, it is clear to me that the last coat of varnish did not stick to the previous coat. There is some contamination on the surface. Those clumps of varnish are what you get when the varnish does not stick but the surface tension (as it dries) pulls the wet varnish back into a ball. Is the varnish the problem or some surface treatment you gave the previous varnish coat--well, we are not going to be able to determine that. You are going to have to do that. Run some tests. All it takes to get into trouble is to use a polish or lubricant on the varnish coat before putting the next coat on (and this polish or lubricant contains silicones). This is a well-known problem in the business of finishing. There are also products that you can add to the varnish to help it wet the surface (fisheye preventer??). Shellac is your friend. Mike D
  5. Mike_Danielson

    Oil varnish sweating

    It looks like you goofed up and contaminated it with something like silicones. That has already been pointed out to you. Strip the instrument with alcohol. Run tests on scrap pieces of wood to find out where the problem arises. Here is the secret that the old guys know--coat with a thin shellac coat between varnish coats to act as a contaminant seal. If you never find the problem, this will still work. Mike D
  6. Mike_Danielson

    Houshold LED lights than don't strobe? Does anybody know of any?

    I did some searching on this and came back confused. There are LEDs that work at 500,000 hz, but I could not find any for sale. This high frequency would solve the problem. There are probably bulbs that have a built-in power supply that convert the AC voltage to DC, but I could not find any for sale. Vendors talked about it, but I could not find any products that use AC and are flicker-free. There are DC LEDs that work at 12 volts--they are for campers and such. These are for sale all over the place, but they require a 12 volt DC power supply (which is readily available). The type I found have the same screw-in mechanism as the conventional light bulbs. So, there is a way to get LED bulbs that will not flicker. Mike D
  7. Mike_Danielson

    Wolf on viola

    Let's start with something simple: Place the mute at the 1/4 afterlength position (closest to the bridge). Also try it when the mute is between the C and G strings at the same position. The way we fix this on cellos is to place a small weight on the afterlength at approximately the same position on the G-string. If there is no loss of sound quality with the magnets, then keep doing it. I am not comfortable with replacing the bassbar, and the soundpost is on the wrong side of the instrument where the resonance is taking place. In other words, the magnets are placed on the location where is resonance is located. Mike D
  8. Mike_Danielson

    Tonerite use

    Henry Strobel publish a book by Prof. Gerhard A. v. Reumont, " How to Improve the Resonance Conditions of Musical Instruments by Vibration-Dedamping." The professor uses a out of balance electric motor which is attached to the bridge. It spins at a high RPM. And he can show from acoustic measurements that it has an observable effect. The forces that he uses are a lot larger than what the tonerite is capable of. I am uncomfortable with a motor that is out of balance turning at 10,000 rpm which might be near my face or the house windows (in case something goes wrong) If you search the internet, you can find services that will do this for you. What I do (on occasion) is take a speaker apart and attach a wood stick to the electromagnet 'cylindrical slider piece'. The other end of the stick pushes against the top part of the bridge, and I use a classical music station and amplifier to drive the bridge. Play it as loud as your spouse can tolerate. You have to have a way to mount the speaker--I will let you figure that out for yourselves. I find it has a useful effect, but you can find that it breaks the instrument in enough that the wolf(s) becomes more audible (in my experience). I consider the tonerite to be a toy. Perhaps, it is a "special" toy for some people. Mike D
  9. Mike_Danielson

    Madder Alum Rosinate

    Jackson and others: it is not possible to say how much effect the rosinates have on the instability of the Michelman varnish. Maybe it is just due to the low temperature combination of oil + rosin, but the rosinates may also play a role--this remains unproven. In other words, adding rosinates to a cooked varnish may also cause instability. I remember a few years ago when Darnton was pushing his varnish which is a variation of the infamous megilp. And just like todays discussion, there are true believers that make claims of success. The only thing you can "hang your hat on" are the recipes of Mrs. Merrifield. A cooked oil + resin varnish, and she does not mean going to 120 degree C as adequate cooking. Is the reason you guys pursue this Michaelman varnish because you cannot make a cooked varnish like Hargrave details? His recipe is very clear, but I appreciate that there are a lot of people that cannot make marinara sauce. As I said in my previous post, since you are comfortable going going away from the masters' recipes, take a look at the quinacrodones since they are color fast. Mike D
  10. Mike_Danielson

    Madder Alum Rosinate

    Don has recalled an important issue. A number of years ago, John Masters revealed what time had done to the Michelman varnish. It shrinks, cracks, falls off etc. I think John lives in Cincinnati and saw first hand what age does to the varnish (and reported it on Maestronet). Michelman lived in Cincinnati and published his book in 1946; so plenty of time has gone by. In other words, the Michelman varnish is unstable. Is the Alizarin you are using really alizarin crimson (which is already a lake)? Why not look at the quinacrodones--they are very light resistant. Since you are already getting away from what the Italian masters used, you might just as well look at a pigments which could never have been used by the masters since they were invented about 60 years ago. Mike D
  11. Mike_Danielson

    Aluminium cello pegs?

    Impact punch works very well when you find a stuck ebony peg. It lessons the danger of breaking the pegbox, and you can reuse the peg. These punches (sharp end installed in punch) are used to place a indentation in the metal, making it easy to center the drill. Everyone who does mechanical work needs one of these. So, don't be pigheaded about it, Jacob. Mike D
  12. Mike_Danielson

    Aluminium cello pegs?

    Use an impact punch: https://www.mcmaster.com/center-punches Remove (unscrew) the sharp end and place the punch directly on the protruding peg end, and press until the punch applies a sharp blow to the peg. Hold the other side of the peg box with your hand. Easy as pie. Mike D
  13. Mike_Danielson

    Suggestions for how to address this knot in my new Krenov plane?

    It looks like Thomas is a bit of an "excessive/compulsive." You guys forgot to point out that wood planes are easy to fix when they go wacko. In a few months when the internal stresses relieve themselves, this plane will need some fine tuning. This is easily done with a scraper. Eventually, the plane will stabilize. It would not hurt to put some of the violin varnish on it--you know--the stuff that flunked out in your testing or comes from a commercial source that you no longer trust. Mike D
  14. Mike_Danielson


    And now for a completely different idea: 1. Since the old repair used a bad glue like aliphatic or epoxy, use a hair drier to heat the peg box up to where you can just barely touch it (about 55 degree C). These glues are thermoplastic and you may be able to "rebreak" the glue joints apart. If this works, then remove the glue by scraping with a knife on the fracture surfaces. 2. Reglue with hide glue, and bush. 3. Install mechanical pegs because they will not restress the glue joint like the friction, tapered pegs do. Mike D