TimDasler

Members
  • Content count

    65
  • Joined

  • Last visited

About TimDasler

  • Rank
    Member

Contact Methods

  • Website URL
    TimothyDasler.Com

Profile Information

  • Gender
    Male
  • Location
    Orford, New Hampshire
  1. Downforce Experiment

    This sort of commentary is entirely unproductive, and has no place in this forum in my opinion. Not to mention that the validity of one's statements is unrelated to either anonymity or how much hot air you're blowing.
  2. Custom suction rib system, save 80 % of timeā€¦

    I like the jig. I've been wanting to try making a suction jig for rib holding during planing and scraping, but haven't gotten to it, partially because I wasn't convinced it would hold tight enough. If it stays put under a safe-t-planer I presume it doesn't shift around, so you could also plane and scrape it in there or does it slide around if it isn't butted right up against that lip? Have you done your final planing and scraping using that, if so, did it work well for that as well? The jig I've been using instead is a flat board with 600 grit sandpaper attached with spray adhesive for a higher friction surface, then use two 1/8" wooden pins to hold the end. Two holes are drilled through the end of the rib on one or both ends, so you lose the last 10mm of the rib or so, but it allows you to plane and scrape in both directions without fear of cracking the rib. You can plane right over your pins and not hurt the plane. Don't have a clamp to work around, and when you want to check your thickness you don't have to undo a clamp. Just pick up the rib and check it. Overall, it's a big improvement over clamping down the rib, but your box is one step closer to my "ideal" contraption, which would be a box attached to a suction clamp (or shop vac works I suppose, just more noisy I think) with a foot pedal to engage and disengage or perhaps a valve that you turn to turn the suction off and on quickly so you can pick up the rib and check it easily.
  3. Carving Violin Bridge for Violin with High belly arch

    This makes me question the sharpness of your plane blade and/or the quality of your bridge blanks. For years I was cutting at least 100 violin bridges a week, and I've never had this happen. The only time I broke the uvula was when my chisel wasn't sharp enough and I was cutting the bevels. Usually it was a case of being in a hurry, knowing I should have sharpened it a dozen bridges ago, but I kept working with it until it broke something. I may be wrong, but that's what it sounds like to me.
  4. Bright Sound Tone

    Since you also seemed to be interested in critiques I'd say that the woodwork looks good for the most part. It is clear that you're playing with different models as you mention, so I won't comment on stylistic choices that may or may not follow the intended model. It does stand out to me, though, that there appear to be some waves in the purfling channel. More so on the back, and much of it following the flame. I use a tight gouge in this area, then scrapers focusing on the high spots. The purfling channel and edge work are the only areas on the plates where I use sandpaper, and I finish with a tight roll of sandpaper that ends up looking like a cigarette butt. It resists the pull of the grain and gives you a little more control over the shape. I also think the edgework is too crisp. I'd roll that a little more even if you aren't antiquing. Here are some closeups of the Messiah Strad, which is among the best preserved. Notice that there is still some crispness to the edge on the back, but that peak is a bit further in than yours, so the outer edge is not so square. There's also a more consistent gradual transition up from the purfling I think. There are parts of your purfling channel that are a bit abrupt coming up to the edge. That's also part of what gives the appearance of waviness in the channel. One last thing I notice is that the scroll is well carved, but has some kinks. You might benefit from adding one more scroll gouge to bridge between your flatter gouge and your more curved gouge. You don't necessarily need 7 gouges to do a scroll, but the closer your gouge is to the curve of the scroll the easier it is to prevent flat spots. Part of the appearance of the flat spot is also the result of the inside fluting. I bet it was less noticeable before the bevel, but you could have gone back and skimmed that with a gouge and scraper and evened out the appearance pretty quickly. Some of the bevel lower on the pegbox also contributes to an appearance of unevenness because it appears to change angle and/or thickness just slightly along it's path. It's hard to tell from the photo, but you may also want to flute a little deeper as you exit the pegbox and move up the scroll. Looks a little flat from the photo. So, all that being said, it's nice work overall. I'm just trying to give you the kind of feedback that I know I'm always looking for. Help me see what I'm missing and make the next one better. Nice work!
  5. Bright Sound Tone

    In general a bright sounding violin is one whose upper frequencies are stronger than it's lower frequencies, and since you say it is powerful it seems to me that you want to knock down the lower frequencies a bit. Do your instruments tend to have strong wolfs? If you haven't noticed them, make sure you check above the octave of the lowest string (B-C# for violin, E-f# for cello). A wolf tells you that you have a relatively strong body resonance, stronger than what the string itself can sustain. The upper frequencies are harder to pin down the lower frequencies are fairly straightforward. If you want to knock down lower frequencies you'd be looking at stiffening up the body. It is possible that you tend to have loose soundposts in your adjustment, and if you didn't replace the post a time or two in the first year of the instrument's life, then you almost certainly don't have enough support. That can certainly be part of the problem. Assuming the adjustment is fine, though, you want to consider the overall stiffness of the body cavity. Consider the M2 and M5 shapes that end up making up the B1 modes of the assembled instrument. One reason that tap tones often don't correlate strongly to assembled body modes is that the stiffness of the rib structure isn't taken into account and the rib structure is stiffer than either plate. I haven't seen any good ways of quantifying rib structure stiffness, but I do pay attention to it. I think a straight, rigid rib structure set at a perfect 90 degrees to the plates jacks up the mid range (nasal) tone in particular. It is possible that you've gone too far in the other direction with a very flexible rib structure and thin plates, perhaps a weak bar. Those would all be factors that I would consider. If you don't have wolf notes on most of these instruments I would suspect that the problem might not be in a strong low end, but in a weak high end. That question is a little more tricky to resolve. It is also possible that your issue is one of damping, not stiffness. Your varnish may be soft and heavy or you may be putting something in the ground that dampens high frequencies. Consider trying a something different here or perhaps get a couple white instruments and do one with your usual ground/varnish and try another following another process and see how dramatic the difference is. Of course you'd really need a larger sample size to get a strong sense of the tonal differences, but if it is dramatic I think you'll get some hint of it with a small sample size.
  6. Carving Violin Bridge for Violin with High belly arch

    I know good shops that put the fleck towards the front, and others towards the back. I've also heard a couple fine luthiers discuss starting with the fleck visible on one side, but adjusting it so the long fleck would run straight up the center of the bridge. In the last instance the point of seeing the fleck in the first place is just to grade the bridge and orient it before planing one side to adjust the angle. Essentially, the fleck is the quickest visual cue to see how parallel your grain lines are and if there is a deviation you can see where that happens. Considering that fine shops vary in their orientation of the fleck I've come to the conclusion that it probably doesn't have a huge impact as long as you're within the range of what successful shops do. As for the tall arch, I haven't run in to an arch too tall for a Despiau bridge, which is what I use in my shop. Your arch is pretty extreme, though, so I don't know if it'll work. I generally keep A grade blanks from a few different manufacturers around in case there is some reason that I want to try something different. Wouldn't hurt to collect a few. Not the adjustable foot bridges, though, they're garbage. I have heard many fine luthiers say that you should cut the lower arch to mirror the arch of the top of the violin between the feet. It has always been expressed to me as an aesthetic consideration, but I have often wondered whether there is some functional reason that this habit has persisted. Perhaps a high arch tends to be stiffer and there is some benefit to loosening up the bridge moderately by raising the center of the lower arch. I haven't done any testing to see what tonal effect that cut may have, but I've been curious about it.
  7. Downforce Experiment

    Try and find a copy of Strad3D. It's sold out now, but you may be able to borrow it at a library. Perhaps by inter-library loan as it probably isn't in too many libraries. You'll be able to see some animations that you couldn't study by eye. There's a portion where they show animations exaggerated after measuring the movements with lasers. It helps to actually see what is moving most at different frequencies. Another thought, which I think may have come from Norman Pickering, is to put a tiny metal ball (like a ball bearing) on the end of a flexible steel wire. Then touch it to different areas of the violin and bridge as it is played. You will find that by the time you reach the top of the register the ball doesn't buzz against very many vibrating areas. Mostly the bridge and maybe the f-wings. Other than that you'll probably need some fancy slow motion tech to see what the bridge is doing and even then they're such little movements it will be really hard to discern much. Overall, though, the bridge cut effects the upper register more than the mid-low register. Questions of placement, foot spacing etc... have more broad effects regarding balance, response, tonal quality and such. Also look for 'The Effect of Wood Removal on Bridge Frequencies' by Rodgers and Masino. It has some illustrations of the different motions of the bridge that may illuminate some of the details of bridge motion for you. There's a wealth of scientific study on violins out there if you dig for it.
  8. Shoulder rest effect on tone?

    See if you can borrow a shoulder rest from someone to try different types and perhaps try some different positions of the shoulder rest. It is possible to have placement that causes you a problem, although it's not common. Usually players just kind of slip it on anywhere and it doesn't stand out as being any different tonally. In particular I'd suggest setting it so the feet are not perpendicular to the centerline of the instrument and see if that makes any difference for you. Also try the shoulder rest in general a bit closer to the end block. You could also try tucking a foam pad under the shoulder rest so it makes contact with the back. Perhaps you could also try holding it differently, clamp down with your jaw less, don't put the shoulder rest on too tight. These things won't necessarily have a big impact, but it should be pretty easy to play around and see what you notice. In general I'd be more inclined to think that the tonal effect that you're describing is the result of a stiffening of the structure rather than damping effectively taking a way a sound that could be described as the difference between steel strings and synthetic. The vibrations that effect high frequencies don't seem to travel around to the back all that much, but a stiffening of the structure can bring them out as they radiate from the top and bridge. I would expect a stiffer rib structure and/or top to effect these frequencies the most, and only one of those two would be directly effected by the shoulder rest.
  9. Downforce Experiment

    Thanks for doing this Don. The results are consistent with what I would expect based on my discussions with one of the engineers for a string manufacturer. If you come across any photos from acoustics research these days he seems to show up kind of like where's Waldo. In any case, what I took away from the conversation (prepared to accept that I misunderstood him) is that the break angle had very little effect on the tone (after rolling his eyes I recall him saying something along the lines of it being virtually nonexistent. not nothing, but certainly not what makers think.), but that the other changes to things like the bridge were where the vast majority of the tonal changes were coming from when the angle was changed. This result seems to support that, although I'd agree with Martin's commentary about more rigorous testing required to assess more of the qualities of the instrument in each arrangement. I had been hesitant to accept this explanation because I do have a lot of faith that maker's collective intuition about things is often a good practice to follow, and am cautious about assumptions made based on simplified models for scientific analysis. The idea that the angle effects tone is so prevalent I haven't wanted to let the idea go completely. Of course this is why I wanted to do an experiment, and I think you've saved me the effort. Thanks again.
  10. Laser Burning Bridge Name

    I was taught that the brand belongs on the tailpiece side if you're going to plane off the manufacturer's stamp, but if you want to leave it there to show that you're using a high quality blank, then your stamp has no place else to go but the fingerboard side. Seems only logical to face your stamp towards the player, but people handling violins, not playing them, are much more likely to see the other side. As for smearing, I run the stamp over a candle flame to pick up the carbon, then after stamping it I leave it alone for a while. It only smears shortly after it is stamped. You'll want to do your bridge staining and/or sealing before the stamp so you don't have to touch that face immediately after.
  11. Perpendicular does not exist on violin tops...

    Ah, that simplifies the model significantly. I've been hung up on the idea of a big plate and sliding a saddle contraption up and down, but now I'm thinking of a rod, which may even be curved at a radius of the top of the bridge to the button, so sliding the tailgut up or down would maintain a near perfect distance. I suppose the top of the bar should still be supported back down to the lower block so you can prevent the rod from flapping like a reed under the vibrations. The model in my head based on your suggestion seems like it may even be relatively easy to swap between instruments without modification.
  12. Perpendicular does not exist on violin tops...

    Yes, there are numerous other issues with discerning the effect of a change, and to some degree we rely on perception of changes over time, which may also be unreliable. Over time, though, that is what has developed the most successful makers. One tool that I sometimes use to tackle some of the changes in environment, player, listener etc... is to use the chart below along with 2 instruments which are not altered between 1st and second listening. Not really necessary in the short term, but if you want to compare something after a week or two, such as strings breaking in, then it is helpful to have some sort of reference, which would be your control. I think using a bridge jack to replicate the effect of a change to the break angle of the string comes with it's own flaws. Among them is the change in playability with higher string heights and change to the after length unless you are going to adjust it as you go in which case you don't need quick adjustment of a jack. I'm also not convinced that the jack will work similarly enough to a proper bridge to really answer any questions. Another tool to combat the variables is sample size, and the more experience you have the easier it is to recognize the trends. Violin Tone Map.pdf A note about the 'tone map' I realize this concept is also flawed in it's own way, and the terminology is vague as any tonal descriptions. I often end up making notes in the margins and having at least one additional listener. I find that the form helps me to think about the tone in an organized way and that alone helps me remember better when I come back weeks later. It takes a little getting used to, but I do like it for some types of observation. I don't use it all that often, though. Ultimately it is a great tool for memory, discussion, and recognizing how your observations of your control instruments have changed from first listening to subsequent listenings.
  13. Perpendicular does not exist on violin tops...

    I've been a professional luthier for 15 years, and I'm well aware of what musicians are likely to perceive, and also aware that many of our assumptions of cause and effect are incorrect because we are usually changing multiple variables at once. I did not say that it wouldn't be noticed. I said that it would be subtle, and that subtle change may be attributed as much, if not more, to the change in mass at the top of the bridge than to the break angle itself. With that context, it is worthwhile to consider the way in which the bridge is altered or replaced to be conscious of limiting changes to an instrument that is pleasing to it's current user, since the statement was in response to a comment about an instrument that was well liked by the current player. From your description of the changes to the bridge it sounds to me like you are over-estimating the effect of the string angle and under-estimating the effect of the cut of the bridge. From the sound of it you took 1mm off the feet of the existing bridge, which is a pretty significant change. If the bridge had feet so thick that you could take 1mm off, then it wasn't ready for a tonal test. If you cut a replacement bridge all bets are off unless you are capable of working to fine precision, and based on your description thus far you are probably quite far from being able to replicate a bridge in such detail to eliminate the variable. If you ended up with extremely thin feet, then that could contribute to a loss of power. If you over-cut the bridge in general then you sometimes have a thin, brittle tone. If still in doubt, consider how little mass you need to add to the top of a bridge for significant tonal effect as with mutes. Try taking 1mm of material out of the ankles and hear the change from a 4.5mm ankle to a 3.8mm ankle. Most likely you'll hear an improvement in the quality and response of the low strings with the change to the ankles. If your feet were very thick initially that would also have a significant impact. I did a tone test with 3 bridges cut within the parameters of 'normal' but one on the thick side, one on the thin/light side, and one was my ideal stock bridge cut. I did a blind test with a musician and after a single play through he could identify each bridge as I swapped them out. So again, I'd say that the bridge has such a big impact that you really can't remove that variable without doing something like what I proposed earlier or what Don has constructed.
  14. Perpendicular does not exist on violin tops...

    Pretty much. Doesn't look like that slides, though, and the TP looks like it touches the saddle in the second portion. Based on Ted White's research I have been paying a lot more attention to the tailgut length because it seems like it has as big of an effect, if not more of an effect than the after length. I suppose, as you say, that I was over-thinking the experiment and should have just tried something on an extreme to evaluate what happens rather than worrying about the ideal design of a complicated sliding contraption. I'll be interested to hear what you discover.
  15. Perpendicular does not exist on violin tops...

    When you're talking about this small of a change the effect is subtle. In fact one of the string engineers who is involved with Oberlin and many other acoustical studies has insisted that makers are over-estimating the effect of the break angle. I don't want to misquote him, but what I took away from the conversation is that he believes the tonal changes are due to changes to the bridge or other factors, not the break angle or an increase in downward force on the bridge. I know a lot of people feel differently, but again, when you're talking about a subtle shift in tilting the neck 1/2mm to one side it won't be dramatic.