| View previous topic :: View next topic |
| Author |
Message |
kubasa
Member
Joined: 13 Sep 2007
Posts: 212
|
 Posted: Thu Feb 19, 2015 1:57 pm Post subject: Bass bars |
 |
|
Besides straight, even grain, what do you look for when choosing a bass bar for your top plate? Do you try to match the grain with the plate grain? I've always looked through my supply of wood and looked for something with a nice ring to it and straight even grain. Beyond that, I haven't given it all much thought.
On my current instrument, I got to wondering if maybe I should be thinking about the wood selection process a little more. Maybe I'm over thinking things....
James |
|
| Back to top |
|
 |
Dave Chandler
Super Member
Joined: 31 Oct 2007
Posts: 691
Location: Mt Mitchell in North Carolina
|
| Posted: Sun Feb 22, 2015 1:11 am Post subject: Bass Bars |
|
|
James, sounds like you're already covering all the bases in selection of bass bar material. I try to make myself a bunch of bass bars from the same spruce I get my tops from, but not everyone cuts their own spruce. I think getting the shape correct is even more important, and I think somewhere in a post sometime back Michael Darnton gave his standard bass bar measurements, which when measured through the top accounted for the thickness of the top.
_________________
Dave in the Blue Ridge
Southern Violin Association
"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill
"I took the road less travelled, and now I don't know where I am." Marco Polo |
|
| Back to top |
|
|
DonLeister
Moderator
Joined: 29 Mar 2007
Posts: 383
Location: Richmond, VA
|
| Posted: Sun Feb 22, 2015 9:59 am Post subject: |
|
|
You probably do this already but didn't specifically point it out is to keep the split of the wood parallel with the flat plane of the plate. I either start little split at each end to see how it is running or look for the tiny sap lines on the face of the blank.
Other than that i try to keep things reasonably consistent, not too few or thick grain lines in the blank. |
|
| Back to top |
|
|
kubasa
Member
Joined: 13 Sep 2007
Posts: 212
|
| Posted: Sun Feb 22, 2015 1:33 pm Post subject: |
|
|
Thanks Don and Dave. I'm on the right track - just over thinking things again. My last violin, I ordered wood for a viola and the cut was so generous that I was able to cut 8 bass bars from the wood I received. In any case, I'm going to look for the post that you mentioned Dave. I'd like to read that.
James |
|
| Back to top |
|
|
Mat Roop
Senior Member
Joined: 24 Mar 2007
Posts: 911
Location: Wyoming Ontario
|
|
| Back to top |
|
|
Dave Chandler
Super Member
Joined: 31 Oct 2007
Posts: 691
Location: Mt Mitchell in North Carolina
|
| Posted: Sun Feb 22, 2015 7:01 pm Post subject: Bass Bars |
|
|
That's a shortened version of another longer more detailed posting which I'm quoting below --
| Michael Darnton wrote: | The system I outlined on Maestronet is, I think, the one Andres refers to.
Divide the length of the bar in half, half the halves, and do the same again. This will divide the bar length into eights (nine marks, total, counting the ends). I don't start exactly at the ends, but about 5mm inside, to allow for something like a bevel or Wurlitzer tab at the very end.
Make the height of the bar, including the thickness of the top (measuring with a graduating caliper), at each mark, from one end to the other, 5.0mm, 7.6, 10.2, 12.8, 14.0 (center), 12.8, 10.2, 7.6, and finally down to 5.0 at the other end. This makes a symmetrical bar, highest at it's center.
Map these dimensions out on a straight line on a piece of paper, and you'll discover something interesting. If you start your bar 40mm from the ends of the plate, and extend the given thicknesses down to zero, you'll discover something else interesting. As long as you're drawing things, mark in the plate thickness (a nominal 2.5mm) parallel to the baseline that represents the flattened outside arch surface, the ends of the plate, and draw in ribs and linings in their proper locations.
I am not the source of this plan; it was developed, as far as I know, by Carl Becker. The shape of the bar is exactly the same as the one I was taught to make by eye. Carl couldn't decide if the center should be at the center, or at the bridge, so he split the difference. I think that the support is needed at the narrowest spot between the f-holes and at the bridge, and if you put the center in the center, both spots are covered about equally.
The most important aspect of the heights of the bar is, in my opinion, to keep them symmetrical out from the center, very precisely. The exact cross section isn't as important, as long as, again, it's symmetrical out from the center. I was taught to make it bullet-shaped in the center, moving into semi-circular at the ends. Obviously, though, the cross section will affect the overall strength and weight of the bar, if you feel the need to change something in that direction. I usually make such changes as width and height rather than cross section.
The purpose for symmetry is to avoid generating dissonance in the vibration of the bar, from imbalance. You can probably achieve this by some exotic tapping routine (actually you can, and it's a PITA), but the caliper works as well and is faster.
I agree with Jeffrey, that mainly the bar has to do with response, assuming you make it correctly in the first place. You can damage all sorts of things with a incorrectly designed bar, though. I have experimented a lot with using the bar to change stiffness, and thus tone, on the bottom end, and have been able to damage the sound, but not do too much in the way of curing an instrument's innate problems in this area. My experience has been that the worst problems on the bass end usually originate around the perimeter of the plate, not from the area where the bar has influence, and that, therefore, the bar isn't likely to do much. |
_________________
Dave in the Blue Ridge
Southern Violin Association
"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill
"I took the road less travelled, and now I don't know where I am." Marco Polo |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
