Double Bass Another angled endpin

[Don Kasper]

Guess I got more out of my physics class than I thought!

I am speechless, again...#5
West Coast Cultural Elitist!!!
(jk)
Thanks!

 

[Tom Lane]

Tom.
I agree with you about the Laborie. On nothing else however. When I have time I will try to make up some graphics to show what I mean. You really took physics?

I'd like that, thanks. Physics? In high school and college it was required. Guess what grade I got!

 

[robobass]

OK. A bit simplified, but gives the idea. I only got a C in Engineering Mechanics 210, but I feel like I still got a lot out of it. With a straight pin you will have counterclockwise torque based on the length of the pin and your playing angle. If your bass weighs 30 lbs. and you extend 6" and angle at 30°, then you have 90 inch pounds. If you play with the same height and angle with an Eggpin style setup then you have maybe 10" between the socket and the contact point on the floor, and will have 150 inch pounds in a clockwise direction. Ironically, the torque increases with angle with a straight pin, and decreases with an Eggpin. If you hold you bass vertically then there is no torque in a straight pin. With an Eggpin the force would go up to 300 inch pounds!

As you see, I'm not talking about the torque you think I meant, but that in the side axis.

 

[robobass]

Edit:
Cobwebs! I forgot to recalculate the new angle in the sketch on the right. In this example it would be about 38°, changing the torque measurement to 185 inch pounds. Anyway, the idea is that you at least double the prying force on the socket and block when you use a system like this. In this example you would be creating a similar torque by laying you bass on its back, extending the pin 12", and hanging a 15 lb. weight from the tip. The block could probably withstand that, but what about if the bass slips out of your hands and comes down hard on the stopper? Also, there is tone to consider. This much twisting force on the block could potentially reduce resonance, and some RobPin users have said that the bass seems more open compared to with their straight pin.

 

[Tom Lane]

OK. A bit simplified, but gives the idea. I only got a C in Engineering Mechanics 210, but I feel like I still got a lot out of it. With a straight pin you will have counterclockwise torque based on the length of the pin and your playing angle. If your bass weighs 30 lbs. and you extend 6" and angle at 30°, then you have 90 inch pounds. If you play with the same height and angle with an Eggpin style setup then you have maybe 10" between the socket and the contact point on the floor, and will have 150 inch pounds in a clockwise direction. Ironically, the torque increases with angle with a straight pin, and decreases with an Eggpin. If you hold you bass vertically then there is no torque in a straight pin. With an Eggpin the force would go up to 300 inch pounds!


View attachment 3744459
View attachment 3744460
As you see, I'm not talking about the torque you think I meant, but that in the side axis.

Thanks so much for the diagrams, formulas, and analysis Rob. Let me mull this over a bit.

 

[Tom Lane]

Edit:
Cobwebs! I forgot to recalculate the new angle in the sketch on the right. In this example it would be about 38°, changing the torque measurement to 185 inch pounds. Anyway, the idea is that you at least double the prying force on the socket and block when you use a system like this. In this example you would be creating a similar torque by laying you bass on its back, extending the pin 12", and hanging a 15 lb. weight from the tip. The block could probably withstand that, but what about if the bass slips out of your hands and comes down hard on the stopper? Also, there is tone to consider. This much twisting force on the block could potentially reduce resonance, and some RobPin users have said that the bass seems more open compared to with their straight pin.

Sorry for the delay, I was out of town last week and finally got around to considering this more carefully. So now, I'm not sure what to think but I think you may have convinced me. I took my endpin out of my bass and pretended that my hand is my bass while resting my endpin on the table and I could definitely feel the force being applied to the far side of the endpin socket. Switching my endpin to a straight pin, I could easily feel that the force on the far side of the socket was much less. That would seem to support your conclusion and indicate that my thinking was mistaken.
First time that's happened!
Seriously, as of now, I think you're right and I'm wrong, but I'm going to continue to mull it over. I can't help thinking that somehow the roundness of the endpin plug and hole dissipates much of the force, but I can't imagine the physics that would back that up. Regardless, thanks for your help in deepening my understanding!

 

[LouisF]

I saw this on Ebay for less that $20... The tip of the endpin screws into the socket and the bass sits (safely from what I can tell) at @ a 25 degree angle. It mutes the sound a little but not much. I sit on a low stool with the endpin barely out. I don't know how it would work for taller/standing/higher pin players.

 

[Fleo]

I saw this on Ebay for less that $20... The tip of the endpin screws into the socket and the bass sits (safely from what I can tell) at @ a 25 degree angle. It mutes the sound a little but not much. I sit on a low stool with the endpin barely out. I don't know how it would work for taller/standing/higher pin players.

Works on most surfaces, not so good on tiles, or stone in churches, lost mine long ago.

 

[robobass]

It's just an endpin rest though. Has no effect on balance or center of gravity, which is what angled pins are used for.

 

[LouisF]

Yeah, I just use it in the practice room. It puts the bass at a nicer angle for me, since I sit on a low stool.

 

[Papageno]

It's just an endpin rest though. Has no effect on balance or center of gravity, which is what angled pins are used for.

As a physicist and bassist, I have been puzzled to see people (including people making and selling them) stating that angled pins change the location of the "center of gravity" of the bass.

That is incorrect. The center of gravity is the center of mass of an object: since both traditional pin and the angled pin have much less mass than the rest of the instrument, replacing the traditional pin by the angled one has a completely negligible influence on the location of the center of gravity.

The effect of the angled pin is to move the point of rest of the bass closer to the vertical projection of the center of gravity. This has a consequence of reducing the proportion of the weight of the instrument that is supported by the player.

 

[robobass]

Well, I guess we have been using the term "center of gravity" rather loosely. However, the way we use the term seems clear and consistent to all involved in discussions like this, so where's the harm?

 

[Chris Fitzgerald]

Well, I guess we have been using the term "center of gravity" rather loosely. However, the way we use the term seems clear and consistent to all involved in discussions like this, so where's the harm?

This reminds me of the discussion about string height and tension. To the player, when the strings are higher above the board, the strings feel as though they have more tension. The science-minded folks in the bass community inevitably come out at some point and remind everyone that the height of the strings above the board does not affect string tension in any way.

Years ago, luthier Nnick Lloyd introduced me to the term “perceived tension” to address this difference, and I’ve been using it ever since. Maybe the same sort of compromise would work here?

 

[robobass]

Indeed. Perhaps we should say "balance point"?

 

[Chris Fitzgerald]

We could say that, but we might have to pay royalties to @damonsmith.

 

[Papageno]

Well, I guess we have been using the term "center of gravity" rather loosely. However, the way we use the term seems clear and consistent to all involved in discussions like this, so where's the harm?

Sure there's no harm. But would there be any harm in giving the correct explaination?

I note that you made an effort in attempting to explain the principle of the angled pin in post #43 and I have no objection to what you wrote there.

Indeed. Perhaps we should say "balance point"?

I think to most appropriate would be to say that the angled pin shifts rest point, or contact point (on the floor, since are also contact points on the players body) closer to the vertical of the center of gravity.

This reminds me of the discussion about string height and tension. To the player, when the strings are higher above the board, the strings feel as though they have more tension. The science-minded folks in the bass community inevitably come out at some point and remind everyone that the height of the strings above the board does not affect string tension in any way.

The tension is the force that is applied to the string along its longitudinal direction. That is not what the player directly experiences, as nobody pulls the string longitudinally. To stop the string, the player has to press the string towards the fingerboard, and that is this transverse force that is of interest to the player.

The general formula for the transverse is (a little bit) complicated, but there are 2 relevant cases, where it can be significantly simplified:

(a) at the octave (middle of the string): there the transverse force is equal to the tension, multiplied by the string height, multiplied by 4, and divided by the string length. So, taking roughly a tension of 25 kg, and a string length of 1 m, this gives a transverse force of 0.4 kg for a string height of 4 mm at the octave, or 0.2 kg for a string height of 2 mm.

(b) close to the nut (say for an Ab on G string): in this case, the formula for the transverse force reduces to the tension, multiplied by the string height, divided by the distance between the nut and the finger (approximately 5 cm). So, for a tension of 25 kg, the transverse force experienced by the player is 0.5 kg is the string height at the nut is 1 mm, or 0.25 kg if the string height is 0.5 mm.

I hope that's of some interest to someone...

 

[damonsmith]

We could say that, but we might have to pay royalties to @damonsmith.

I did name my label after this idea (as well as reference to freestyle BMX). I think the bent end pins changes the balance point so the whole fingerboard is easier. It does make the low register slightly more difficult, at least at first. I think it is worth it on the whole.
I balance the bass on my gut for a very similar result. Finding that right balance whether you change the pin or not is really very important.