cue calculator

[d_b]

EDIT: web-based (non-spreadsheet) version of this calculator is now available.
EDIT: http://dbv.netavail.net/pj-calc.html


As part of my ongoing (and first ) cue design/building experiment, I created a spreadsheet to calculate the approximate weight and balance point of a (plain jane) cue given the dimensions and material properties.

I'm sure I re-invented the wheel here, but I didn't have access to anyone else's wheel...

If anyone else out there has a similar tool, and has a few minutes to check my calculation(s) against those from your design tool, I'd appreciate it if you could let me know if my balance point calculation is reasonably correct.

EDIT: spreadsheet unpublished. use web-based version.

You won't be able to change/edit that spreadsheet, but you can make a copy of it for yourself by selecting the "File > Make a Copy ..." menu item, then you can adjust the inputs as you wish. The yellow bits are inputs and the blue bits are calculated values.

All inputs are in inches, ounces or lbs/ft^3 (for density).

If you export to excel or open office format, the balance point calculation won't work, because it's a custom function written in javascript.

cheers!
Brent

 

[ELBeau]

I went to "File-Make a copy" to save for future use, but that option's not available (grayed out). Can you double-check the settings?

 

[d_b]

You have to be logged in to Google docs before that option is available.

Sent from my Galaxy Nexus using Tapatalk 2

 

[MVPCues]

Hi Brent. I wrote myself a computer program to aid with weighting and balancing cues. My program includes coring (full length, individual component, multiple diameters, partial cores, etc), rear cavities, wraps, ringwork, shaft information, etc, etc.

I entered the basic information you have in your spreadsheet. I had to guess at a few things though. You don't give a butt cap length, so I assumed 1/2" butt cap length, making your sleeve actually 3 inches and not 3.5. You list the joint collars as 0 weight, so I assume this is a cue with no collar. I don't know what a B connecting pin is, so I stuck one in the cue 3 inches from the rear, along with an A joint connecting pin, both weighted what you list. I entered a bumper and joint pin with the weights you give.

You come up with a cue weight of 18.53. I come up with a weight of 17.97. If you do not take into account the wood removal for the joint pin installation, the wood removal for the butt cap riding the tenon, the wood removal for the connecting pins, etc, this could easily explain a large part of that difference. My program breaks the cue up into very small segments and takes into account all of these things as it aggregates each slice of the cue into a total weight. It also includes things like the direction the A-joint tenon runs. This wouldn't make a difference in this cue since both the forearm/sleeve density and the handle density are so close. There are other miscellaneous settings in my program that could affect the weight; coring tolerances, finish thickness, glue density, etc.

On the balance, you list 20.25. I come up with 18.57. Are you actually calculating moments to come up with a balance point? You don't include the balance point of the shaft in your data. Since the shaft is treated as one unit, a balance point of the shaft must be used to calculate the moment of the shaft component. Each time a section of the cue changes in terms of density of a cross section, a moment needs to be calculated for that cross section for a given length in order to correctly come up with a balance point of the cue. This is why I cut the cue up into very small slices during the calculations. As I calculate the weight of each slice given all of the input data, I also calculate a moment of that small slice so my balance point prediction is done using moments along the entire butt section.

I don't know how you are calculating the balance point, so I can only speculate that you are not correctly calculating moments for all of the various components.

Here is a screen shot of the main form of my program with your entered information. There are additional screens for recording weight bolts, all of the ring work information, wrap information, etc. If you see something I may have entered wrong, let me know.

 

[d_b]

Heh. So my wheel isn't nearly as round as yours!

I did the same slicing over the lenght of the cue, using a single wood density for each slice. And then adding any additional weight for hardware/rings. Nothing as precise as your modeling of the cue! I suspected my balance point calculation might be off because the total weight of my slices ended up about a half ounce more than the unsliced calculation with the majority of the difference in the shaft side.

I'm on my phone at the moment. Will reply more later.

Thanks for the sanity check!

Cheers!

Sent from my Galaxy Nexus using Tapatalk 2

 

[MVPCues]

"b-connecting pin' would probably be a pin between the wrap and the forearm, kinda like a jump cue. If so, then his balance point would certainly be different than yours.

dld

I would call that an A-joint connecting pin since the location between the forearm and the wrap is the A joint. I placed a pin at that location, as well as one at the rear of the cue for the B connecting pin. But, the pins are both only .2 ounces. Removing the B connecting pin I placed at the rear of the cue shifts the balance point forward only .02 inches. Not knowing the length of these connecting pins also potentially changes things, but not that much.

Kelly

 

[MVPCues]

Heh. So my wheel isn't nearly as round as yours!

I did the same slicing over the lenght of the cue, using a single wood density for each slice. And then adding any additional weight for hardware/rings. Nothing as precise as your modeling of the cue! I suspected my balance point calculation might be off because the total weight of my slices ended up about a half ounce more than the unsliced calculation with the majority of the difference in the shaft side.

I'm on my phone at the moment. Will reply more later.

Thanks for the sanity check!

Cheers!

Sent from my Galaxy Nexus using Tapatalk 2

Good. If that is what you are doing, we should be able to get closer by some barebones comparisons and more details on the data, or reveal where the hangup is.

Kelly

 

[scdiveteam]

Very Cool Stuff!!!!

Tap Tap!!

 

[d_b]

Kelly,

Again, let me say how impressed I am with the thoroughness of your cue designer/calculator. Very nice! And thanks for taking the time to sanity check my work.

I'll try to explain my approach below... it might become unintelligible as I have only a few minutes before I have to go to a meeting...

I entered the basic information you have in your spreadsheet. I had to guess at a few things though. You don't give a butt cap length, so I assumed 1/2" butt cap length, making your sleeve actually 3 inches and not 3.5. You list the joint collars as 0 weight, so I assume this is a cue with no collar. I don't know what a B connecting pin is, so I stuck one in the cue 3 inches from the rear, along with an A joint connecting pin, both weighted what you list. I entered a bumper and joint pin with the weights you give.

I have assumed the connecting screw lengths are 2", the joint pin 3" and the butt cap and collars at .5"

The weights I list are an approximation of the _difference_ between the actual weight of the hardware and the weight of the wood removed for the piece, such that the weight listed can be considered "extra" for any given position where that weight/piece is added--rather than calculate a the weight of a slice of solid wood, subtract any wood that was removed and add back the hardware weight, I simplified things so the weight could just be considered extra. Yeah, it's not nearly as precise as yours, but this spreadsheet was the result of an evening of goofing around...and I can't really math!

Inputs for your program should be .3oz for connecting screws and .5oz for the joint pin.

To clarify my terminology, which I now know is probably incorrect, the A joint (screw) is between the handle and forearm and the B joint (screw) is between the handle and the butt sleeve. Sorry for any confusion my ignorance of cue construction may have caused!

Regarding the rings/butt cap weights: the weights I list, are, again the difference between the ring/buttcap material and the removed wood. For your calculation, the butt cap should probably be .3, since I assume your slice model is "wood weight - displaced wood weight + hardware".

You come up with a cue weight of 18.53. I come up with a weight of 17.97. If you do not take into account the wood removal for the joint pin installation, the wood removal for the butt cap riding the tenon, the wood removal for the connecting pins, etc, this could easily explain a large part of that difference.

It looks like the majority of the weight discrepancy is due to the difference in the way we calculated the extra/hardware weight.

My model does not account for any tenon at the A/B joint, so that would move the balance point around a bit -- but not 1.5".

Once I've sliced the cue up and calculated the weight of each slice, I iterate over the slices and calculate a force/moment on both sides of the current index in the slices, giving me a force on both sides of a fulcrum/balance point. When the larger force flips from one side to the other, I call that the "balance point".

Anyhow...gotta run to the meeting now. Again, thanks!

Brent

 

[MVPCues]

Kelly,

Again, let me say how impressed I am with the thoroughness of your cue designer/calculator. Very nice! And thanks for taking the time to sanity check my work.

I'll try to explain my approach below... it might become unintelligible as I have only a few minutes before I have to go to a meeting...



I have assumed the connecting screw lengths are 2", the joint pin 3" and the butt cap and collars at .5"

The weights I list are an approximation of the _difference_ between the actual weight of the hardware and the weight of the wood removed for the piece, such that the weight listed can be considered "extra" for any given position where that weight/piece is added--rather than calculate a the weight of a slice of solid wood, subtract any wood that was removed and add back the hardware weight, I simplified things so the weight could just be considered extra. Yeah, it's not nearly as precise as yours, but this spreadsheet was the result of an evening of goofing around...and I can't really math!

Inputs for your program should be .3oz for connecting screws and .5oz for the joint pin.

To clarify my terminology, which I now know is probably incorrect, the A joint (screw) is between the handle and forearm and the B joint (screw) is between the handle and the butt sleeve. Sorry for any confusion my ignorance of cue construction may have caused!

Regarding the rings/butt cap weights: the weights I list, are, again the difference between the ring/buttcap material and the removed wood. For your calculation, the butt cap should probably be .3, since I assume your slice model is "wood weight - displaced wood weight + hardware".



It looks like the majority of the weight discrepancy is due to the difference in the way we calculated the extra/hardware weight.

My model does not account for any tenon at the A/B joint, so that would move the balance point around a bit -- but not 1.5".

Once I've sliced the cue up and calculated the weight of each slice, I iterate over the slices and calculate a force/moment on both sides of the current index in the slices, giving me a force on both sides of a fulcrum/balance point. When the larger force flips from one side to the other, I call that the "balance point".

Anyhow...gotta run to the meeting now. Again, thanks!

Brent

Cool information. I'm sure our weights will be much closer with the added explanation. When I have a chance to digest these added details and make data changes in my program and possibly ask another question or two, I will make another post.

I hope I didn't imply I was wrong and you were right in what I assumed was the A/B terminology. I know there is variation in what they are called, but I had to make an assumption based on what I understand things are called.

Regarding the moment calculations, I break up the cue into .01 inch segments, and calculate the weight of each segment. I calculate one moment for the midpoint of each segment working from the rear of the cue forward.

Tapers and diameters vary enough with shafts so that the balance point of the shaft will fluctate from builder to builder by an inch or two. A brass insert for the small pin guys can affect this a little also. By assuming a conical taper for the shaft, the balance point will be pushed more forward in your calculations, but I don't see it being 1.5".

Also, a .5 ounce pin sounds like aluminum. I think an aluminum pin and no joint collar would be hard pressed to yield a 20" balance point. However, I use a 3/8" pin, so perhaps a 5/16" SS pin that isn't as long as what I use would weigh as little as .5. I assume your balance point is from the very rear of the cue.

Many of the small things I am calculating, such as the direction of the A joint, affect the balance point by as little as .01", but at least some of this added information you highlighted will bring our balance points closer.

Kelly

 

[d_b]

Kelly,

I hacked my shaft calculator into the cue calculator sheet...and uncovered a horrible bug where I'd modeled some of the cones in the wrong direction!

https://docs.google.com/spreadsheet/ccc?key=0Aj66YRiJTrEGdHhRYWtXSWZRa0p4a3RKVnJPSmFQdXc

My balance calculation is _much_ closer to yours now. The discrepancy is probably due to the fact that I'm modeling the complete weight of the bumper in the last slice of the cue -- an incredibly dense, super thin bumper

Dude, I really, really appreciate the sanity check that led me to find my bug!

Would you mind me putting a link to your website or contact information in my spreadsheet to let people know there is a much better cue design calculator available? Oh...I'll need that information as well.

I'm going to edit my original post to remove the link to the old/busted spreadsheet.

Best,
Brent

 

[MVPCues]

Kelly,

I hacked my shaft calculator into the cue calculator sheet...and uncovered a horrible bug where I'd modeled some of the cones in the wrong direction!

https://docs.google.com/spreadsheet/ccc?key=0Aj66YRiJTrEGdHhRYWtXSWZRa0p4a3RKVnJPSmFQdXc

My balance calculation is _much_ closer to yours now. The discrepancy is probably due to the fact that I'm modeling the complete weight of the bumper in the last slice of the cue -- an incredibly dense, super thin bumper

Dude, I really, really appreciate the sanity check that led me to find my bug!

Would you mind me putting a link to your website or contact information in my spreadsheet to let people know there is a much better cue design calculator available? Oh...I'll need that information as well.

I'm going to edit my original post to remove the link to the old/busted spreadsheet.

Best,
Brent

Awesome Brent! Yeah, the shaft cone in the wrong direction would be just about an inch and half in balance I bet. I will still update some numbers shortly for a final comparison if you care to do a last check.

I don't have a web site developed yet, but hopefully that is coming soon. I plan on marketing my program to other cuemakers after I make a few finishing touches to it. I have a fully detailed windows help file with it, will shoot how to videos and post them on youtube, etc. Once I publish the website, if you still want at that time, by all means you will be welcome to add a link to my W&B page.

When I have the page up, I will remember to send you a message.

I should post my updated calculations with the information you provided earlier shortly.

Kelly

 

[MVPCues]

Ok.

I changed the two connecting pins to be 2" in length, and each .3 ounces.
I changed the joint pin to be .5 ounces, with a bore length of 1.8, 3" OAL.
I changed the butt cap to .3 ounces.
I still did nothing with the joint collar because in your original spreadsheet, you listed 0 as net weight gain for the joint collar. So, my calculating is with a sneaky pete joint.

My new weight calculation is 18.52 oz. You originally had 18.53, and this should not have changed when you reversed the cone for the shaft. So, bingo. BTW, I have been dead on when a test (albeit simple) cue butt was weighed and balanced after constructed and machined to final size.

My new balance point is 18.39. Mine actually shifted more toward the back, due to the much denser B connecting pin at the rear after that was corrected to be shorter and heavier. Our balance points will still be off a little because of your assumption of a cone taper, and my assumption of a shaft balance point at 12 inches.

Good job to you also! Doing this kind of stuff in detail is not trivial. It gets really hairy when you try and add shortsplice and full splice cues to the calculations. I have worked on that in my program, but in the end, there are a lot of assumptions related to splices that might weaken the calculations. The amount of data for splices is also a bit exhaustive.

Thanks for the fun thread, feel free to keep in touch on the subject.

Here is the weight bolt window. Location is the start of the bolt measured from the rear of the cue.

Kelly

 

[opiesbro]

Ok.

I changed the two connecting pins to be 2" in length, and each .3 ounces.
I changed the joint pin to be .5 ounces, with a bore length of 1.8, 3" OAL.
I changed the butt cap to .3 ounces.
I still did nothing with the joint collar because in your original spreadsheet, you listed 0 as net weight gain for the joint collar. So, my calculating is with a sneaky pete joint.

My new weight calculation is 18.52 oz. You originally had 18.53, and this should not have changed when you reversed the cone for the shaft. So, bingo. BTW, I have been dead on when a test (albeit simple) cue butt was weighed and balanced after constructed and machined to final size.

My new balance point is 18.39. Mine actually shifted more toward the back, due to the much denser B connecting pin at the rear after that was corrected to be shorter and heavier. Our balance points will still be off a little because of your assumption of a cone taper, and my assumption of a shaft balance point at 12 inches.

Good job to you also! Doing this kind of stuff in detail is not trivial. It gets really hairy when you try and add shortsplice and full splice cues to the calculations. I have worked on that in my program, but in the end, there are a lot of assumptions related to splices that might weaken the calculations. The amount of data for splices is also a bit exhaustive.

Thanks for the fun thread, feel free to keep in touch on the subject.

Here is the weight bolt window. Location is the start of the bolt measured from the rear of the cue.

Kelly

I would like to say that I think both of you are very talented and have put a tremendous amount of work into your programs! As you stated earlier Kelly about wanting to market your's eventual I would think this could be a really great tool for CMs. I know that eventually I will have a copy when my buissness picks up and I can afford it.

Thanks again for putting forth the effort to making this grey area an exact science!

 

[MVPCues]

I would like to say that I think both of you are very talented and have put a tremendous amount of work into your programs! As you stated earlier Kelly about wanting to market your's eventual I would think this could be a really great tool for CMs. I know that eventually I will have a copy when my buissness picks up and I can afford it.

Thanks again for putting forth the effort to making this grey area an exact science!

I really appreciate the kind words. My education is in math, I am a data entry software developer, and I build cues (albeit at a snail's pace) as a hobby, so I guess this program is a combination of all three of those things. It has been fun to develop, and I do think (hope?) it might be a worthwhile contribution to the craft. Initially, I just wanted something for myself to aid in wood selection and coring options kind of stuff for the oddball cue (in terms of weight and balance) that comes along now and then. It then turned into a challenge to myself to try and incorporate as many aspects of cue construction as I could in order to develop an actual cue modeling program.

Thanks again,
Kelly

 

[d_b]

Good job to you also! Doing this kind of stuff in detail is not trivial. It gets really hairy when you try and add shortsplice and full splice cues to the calculations. I have worked on that in my program, but in the end, there are a lot of assumptions related to splices that might weaken the calculations. The amount of data for splices is also a bit exhaustive.

Thanks for the fun thread, feel free to keep in touch on the subject.
...

Kelly

No doubt, the problem isn't a trivial one. My first, aka naive, idea was to find the point in the cue where there was an equal amount of weight on either side of the balance point...and then I remembered something about fulcrums and force. :embarrassed2: I wouldn't even attempt to deal with half/full/recut splices, for fear that my head might explode.

I'll probably port my spreadsheet to a web app, to make it easier to use, at some point. Even though mine isn't as useful as yours, it might be something useful for customers to play around with in order to get some ideas of what they might want (as long as it's a plain jane!) before reaching out to a cue maker.

I would like to say that I think both of you are very talented and have put a tremendous amount of work into your programs! As you stated earlier Kelly about wanting to market your's eventual I would think this could be a really great tool for CMs. I know that eventually I will have a copy when my buissness picks up and I can afford it.

Thanks again for putting forth the effort to making this grey area an exact science!

Thanks.

Kelly's tool looks purely awesome, and I'd imagine it would give new/budding cuemakers a huge head start in designing cues to meet customers' specs/needs. I'm pretty sure that none of the math/numbers is a replacement for good old experience working the woods, but it can provide a useful guide.

I really appreciate the kind words. My education is in math, I am a data entry software developer, and I build cues (albeit at a snail's pace) as a hobby, so I guess this program is a combination of all three of those things. It has been fun to develop, and I do think (hope?) it might be a worthwhile contribution to the craft. Initially, I just wanted something for myself to aid in wood selection and coring options kind of stuff for the oddball cue (in terms of weight and balance) that comes along now and then. It then turned into a challenge to myself to try and incorporate as many aspects of cue construction as I could in order to develop an actual cue modeling program.

Thanks again,
Kelly

:thumbup: I'm a programmer by trade, too. ...and I did it mostly just to see if that (math) part of my brain still worked. lol.

cheers!
Brent

 

[tank69]

Pretty awesome some of the stuff you find while searching! I hope I can still get access to this!

 

[GBCues]

Of course you can - I just bought Kelly's program a few weeks ago.
Kelly is a great guy, he said to call him if I wanted a quick (15 minute) course in how to get started. So I called him and he spent over an hour with me.
The program is very versatile - but as such, takes some detailed input from the user and some time to learn how to use.

Here's the link:http://www.mvpcues.com/cuebalance.php

Gary

 

[tank69]

Of course you can - I just bought Kelly's program a few weeks ago.
Kelly is a great guy, he said to call him if I wanted a quick (15 minute) course in how to get started. So I called him and he spent over an hour with me.
The program is very versatile - but as such, takes some detailed input from the user and some time to learn how to use.

Here's the link:http://www.mvpcues.com/cuebalance.php

Gary

Thanks Gary!

 

[MVPCues]

Of course you can - I just bought Kelly's program a few weeks ago.
Kelly is a great guy, he said to call him if I wanted a quick (15 minute) course in how to get started. So I called him and he spent over an hour with me.
The program is very versatile - but as such, takes some detailed input from the user and some time to learn how to use.

Here's the link:http://www.mvpcues.com/cuebalance.php

Gary

Was it really over an hour? I lose track of time too easily when having fun.

Because of the vast amount of data/options, the program is a bit daunting at first glance. But, the up front time spent learning it pays dividends later once the default settings are configured and template files are created to make each cue build go relatively fast.

Thanks for the plug Gary.