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Proportional Dividers


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I might add a couple comments about the way I measured the planking problem I showed above.

The length of the two openings (4.85 and 4.00 inches) was measured by using a piece of stiff paper. You can see that in the photograph. These dimensions were used in the calculation. 

The width of the planks was measure with a dial set of calipers (with a dial indicator) that is accurate to within 0.001 inch.
post-246-0-51940900-1486065717.jpg

There is no way that you can be that accurate with the proportional dividers.

To pace off sets of repetitive dimensions on a chart it is cheaper and easier to use a simple pair of dividers:post-246-0-15033200-1486065455.jpg

 

Jay

 

Current build Cross Section USS Constitution  http://modelshipworld.com/index.php/topic/10120-cross-section-forward-area-of-the-uss-constitution/

Finished USS Constitution:  http://modelshipworld.com/index.php?/topic/103-uss-constitution-by-modeler12/

 

'A picture is worth a  . . . . .'      More is better . . . .

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Tools are tools, which to use is a mater of preference, confidence, knowledge and the availability of tools to choose from. I may choose to measurement using cubits, 'IE 14.7 cubits, the .7 being an eyeball best guess', and a slide rule for the math or a calculator if I need to measure that result somewhere using a measuring device marked in meters. I prefer to work in decimals, decimal feet unless I need decimal inches, you will find lots of little pencil marks around my fabrication projects. I may measure using a decimal scale with 10, 10 or a thousand divisions regardless of scale, imperial or metric, scales are a simple conversions, divisions are visible things that create refinement in the eyeball reading of a measuring tool and are the single most used method of refinement in any measurement until needing to think about technique to avoid repetitive and cumulative errors. Wife was an inch, foot girl, a defect in her early potty training, had to rid the place of such marked measuring devices, until the lesson was absorbed with comfort, that the end of fractions did not destroy her world, only requirement, was to be aware of the division, inches or decimal feet, I have pocket tapes with both, amazingly the foot marks are common, not double. Why pick on the wife? She wanted, and did help me in my work, Inches were a problem in a decimal world.

Edited by jud
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I've had a set of proportional dividers since my drafting days.  I look at them once in a while.  Never use.  If I need to resize a plan I find it much easier to have it scanned in and reprinted. 

 

Bob

Every build is a learning experience.

 

Current build:  SS_ Mariefred

 

Completed builds:  US Coast Guard Pequot   Friendship-sloop,  Schooner Lettie-G.-Howard,   Spray,   Grand-Banks-dory

                                                a gaff rigged yawl,  HOGA (YT-146),  Int'l Dragon Class II,   Two Edwardian Launches 

 

In the Gallery:   Catboat,   International-Dragon-Class,   Spray

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So I won the Ebay auction and have the proportional dividers heading my way.  I paid a lot more than I should have but I realized the cost of buying new ones was very expensive.  They are made by Dietzgen so I know they are quality.  Hopefully I can put them to good use.

Derek

If you want to build a ship, don't drum up the men to gather wood, divide the work and give orders. Instead, teach them to yearn for the vast and endless sea  

Antoine de Saint Exupery

 

Current Builds

Bluenose - Model Shipways - 1:64 Scale

Fair American - Model Shipways - 1:48 Scale

HMS Winchelsea 1764 - Group Build

On Deck

Guns of History Naval Smoothbore Deck Gun - 1:24 Scale

Finished Builds

Mare Nostrum - Artesania Latina - 1:35 Scale

Guns of History Carronade - Model Shipways - 1:24 Scale

 

Member of the Nautical Research Guild

 

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Congratulations. I hope you enjoy yours as much as I have mine.

Bill

Chantilly, VA

 

Its not the size of the ship, but the bore of the cannon!

 

Current Build: Scratch Build Brig Eagle

 

Completed Build Log: USS Constitution - Mamoli

Completed Build Gallery: USS Constitution - Mamoli

 

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It is interesting to see the two sides of this 'coin'.
If you have used the proportional dividers for a long time, I can appreciate that you like them for various reasons.
In my case, I have a pair and seldom use them, but so be it.
When Jud mentioned his liking for the decimal system (rather than fractions, I suppose) I agree. But when he talks about using a slide-rule - - - - I have to grin because those are dinosaurs in my college collection. Slide-rules are as accurate as proportional dividers and even more difficult to use and understand (I know Jud, you add or subtract logarithmic values, etc.).

The upshot is: if you like the tool you have, use it. If you want accuracy, calculate.

Jay

 

Current build Cross Section USS Constitution  http://modelshipworld.com/index.php/topic/10120-cross-section-forward-area-of-the-uss-constitution/

Finished USS Constitution:  http://modelshipworld.com/index.php?/topic/103-uss-constitution-by-modeler12/

 

'A picture is worth a  . . . . .'      More is better . . . .

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  • 2 months later...

I was rather surprised that some modelers weren't familiar with the proportional dividers.  I find them essential. I suppose because I do a lot of scratch work and I find myself redrawing lines published in old books (Chapelle, etc.) that will be prints of larger drawings reproduced without regard to scale.  With a good set of proportional dividers, all you need is a single identified measurement (a non-fractional measurement is best) and with your dividers set to your working scale, away you go!  Just take a distance from the page in the book and the other side gives you the distance to the scale you've set.  There are, as mentioned, a lot of other things you can do with them as well, such as drawing a square with the same area as a particular circle and vice versa, but I've yet to learn who really needs to do that.

 

I collect fine drafting instruments for my own use.  Most I've bought on fleaBay and I check for listings frequently.  I'll pass on that the prices do vary wildly, depending on condition, quality and rarity.  Condition may not always be a relevant factor if you are looking for a "user."  Some oaf may have scratched his name into the instrument and/or the case may be in rough shape.  That can mean a $100 or $150 reduction, leaving what would be a "mint" $200 instrument going for only $50, yet be entirely satisfactory for use nonetheless.

 

The proportional dividers that you want to look for are the 10" pairs with "110 scaling" or "decimal scaling."  This scaling permits setting proportions in "decimal equivalents" (e.g. 1/2 = .50)  These instruments will have rack and pinion geared adjustment and Vernier adjustment to decimals out to .0005 (If memory serves... perhaps there's an extra zero in there... don't hold me to it.)  These instruments will be manufactured by Keuffel and Esser and Bowen in straight point configuration and right angle point configurations (as pictured above.)  You will likely never see a right angle pointed set on fleaBay.  They are extremely rare.  I expect that at some time Dietzgen made decimal equivalent scaled proportional dividers, but I've never seen a set on fleaBay.  The most commonly offered are the K&E 10" "Paragon" decimal scaled models.  "Paragon" was K&E's top of the line series of instruments and the "110" decimal equivalent scaled dividers were only offered in the "Paragon" line.  They are made of "German silver," which is an alloy of nickel and copper, much similar to monel.  Their "Parogon" were made of cold rolled German silver and hand fitted. (Each will bear matching part serial numbers.  They were sold in silk velvet lined cases. The back of the case in newer production has a metal plate on the bottom with all the various decimal equivalents etched in it, which is quite helpful.  Older models have a cardboard insert (often missing) that has the same information. (The information is easily found on line in any event.)

 

There are also commonly 6" and 7.5" proportional dividers.  The 7.5" models do come with rack and pinion adjustment but not with the more accurate Vernier adjustment feature.  They are, however, useable.  The 6" models do not have rack and pinion adjustment and neither do some of the 7.5" models.  Don't waste your money on anything that does not have rack and pinion adjustment.  While useable, the "slide" adjustment models aren't anywhere near as accurate.  Similarly, pay the few extra bucks for the "110" decimal scaling.  The other proportional dividers have scaling that corresponds to fractions 1/2, 1/3, 1/4 and so on, and settings in between are "by guess and by golly."  Also, you will see "Russian Navy" and "Weems and Plath" proportional dividers offered.  Take a pass on these because they are "navigational dividers" and, although they work the same and are useable, they are scaled for "time" and "distance" proportions for use on maps and their scaling isn't useful for modeling measurement conversions. (You can adjust them for plans measurement conversions by comparison to a rule and/or tick strips, but this is rather tedious)

 

In summary, what you want to look for on eBay is a Keuffel and Esser 10" "Paragon" proportional divider with "110" decimal scaling.  They are relatively common because they were the "professional's choice" for many years.  A "mint" example with an excellent case will sell for as much as $225, but very "clean" examples regularly go for around $125 at the moment.  Examples that are a bit "rough," mainly due to a worn case, can be had for $75 or even $50.

 

If you work from drawings to the scale you are building (i.e. as with kit plans,) you can live without a proportional divider, but if you are working from plans in one scale (or no scale, as in many lines drawings found in old books,) you will be amazed at how you ever before lived without them.  Yes, you can measure a distance and then punch that into a calculator and then measure off the result, over and over again, or you can set your dividers once and then simply measure the drawing at one end of the dividers and have the proportional distance simultaneously provided between the points of the other end of the dividers.  It doesn't get any faster or simpler than that.                                                           keuffel-esser-k-e-806-paragon-proportion

Edited by Bob Cleek
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40 minutes ago, Bob Cleek said:

I was rather surprised that some modelers weren't familiar with the proportional dividers. 

Yeah I bought a Dietz set some years ago that had a rough case and didn't look terribly good for $40. I don't care about the case and all it took was some 1500 grit sandpaper and it looks great and could be used another 100 years.

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Hi Bob;

 

Thank you for the long and informative post.  I wasn't aware that proportional dividers could be had with such a fine adjustment.  I'll keep an eye out for a set.  It is also kind of you to let us know what to avoid.  

 

All the best,

 

Mark P

Previously built models (long ago, aged 18-25ish) POB construction. 32 gun frigate, scratch-built sailing model, Underhill plans.

2 masted topsail schooner, Underhill plans.

 

Started at around that time, but unfinished: 74 gun ship 'Bellona' NMM plans. POB 

 

On the drawing board: POF model of Royal Caroline 1749, part-planked with interior details. My own plans, based on Admiralty draughts and archival research.

 

Always on the go: Research into Royal Navy sailing warship design, construction and use, from Tudor times to 1790. 

 

Member of NRG, SNR, NRS, SMS

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Greetings Druxey;

 

Thank you for the additional tip.  I will keep this in mind.

 

All the best,

 

Mark P

Previously built models (long ago, aged 18-25ish) POB construction. 32 gun frigate, scratch-built sailing model, Underhill plans.

2 masted topsail schooner, Underhill plans.

 

Started at around that time, but unfinished: 74 gun ship 'Bellona' NMM plans. POB 

 

On the drawing board: POF model of Royal Caroline 1749, part-planked with interior details. My own plans, based on Admiralty draughts and archival research.

 

Always on the go: Research into Royal Navy sailing warship design, construction and use, from Tudor times to 1790. 

 

Member of NRG, SNR, NRS, SMS

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On ‎4‎/‎21‎/‎2017 at 4:52 PM, druxey said:

Make sure that the set comes with the tables for setting any proportion you wish. (The photo above shows the paper chart.)

Yes, it's easy to do the math to get a decimal equivalent, but there are a lot of other settings where the chart is really handy.  Older K&E 10" Paragon decimal scaled proportional dividers came with a fabric-hinged folding cardboard chart (which is often lost and missing) and the later models have the settings "cheat sheet" on a piece of metal attached to the bottom of the case.  If all else fails, a bit of googling should turn up a copy of the "cheat sheet" easily enough, or, at worst, a photo of the bottom of the case with a readable settings plate.

Image result for Keuffel and esser proportional dividers

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  • 3 months later...

Once again this forum and the older archived messages are proving to be a valuable resource.  After reading about the use of proportional dividers for planking, scaling plan measurements and a multitude of other uses in our model shipbuilding hobby, I started trolling eBay for a nice set...today I managed to win an auction for a very nice set of K&E Universal Paragon Proportional Dividers...same as the ones pictured by Bob Cleek above, just the earlier case with the paper insert of charts rather than the metal base.  This particular model seems all over the map...I paid $74.95 for mine in very nice condition with a great case....but just a month ago a set sold for nearly $200...so go figure.  I suppose it pays to have patience not only for building our models but also when it comes to acquiring tools!.....

 

Now if I could just locate a set of K&E Copenhagen Ship Curves......

Cliff Ward

Cary, North Carolina

USA

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  • 2 years later...

I got a cheepo brass pair off ebay last year (from India) for £10. Actually very well made, I was surprised.

If you look up how to use them there's much to be done.

Of course you get what you pay for, but mine are capable of doing all the tasks I found listed.

Ideal for marking discs and cylinder shapes into equal segments as required. A ships wheel comes to mind.

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  • 1 year later...

That's not a bad price at all for what's there. If you got them down to $100, you would be doing really well. The Paragon proportional dividers alone are worth that.  "Anvil" was Keuffel and Esser's "second best" line out of a half dozen or so, surpassed only by their "Paragon" line. What is missing is a spring-adjustable large (6"?) dividers. These had an adjustment screw on the side of one leg which, when turned, provided extremely fine adjustment of the divider points to permit very exact measurements. There is a small dividers in the set of three "bow" instruments in the case, and the proportional dividers will serve as regular dividers comparable to the missing dividers in the Anvil set, so the absence of the large dividers doesn't limit the usefulness of the collection of instruments that are there. If one monitors eBay "drafting instruments" for any length of time, it should be easy to pick up a comparable replacement divider, though perhaps not an Anvil model, for a very reasonable price. "Stray" instruments from sets aren't worth anything near a complete cased set to the collectors' market. They show up on eBay often in "lots" of drafting instruments, which, if you are looking for a single item, can often be a very good deal.

 

If you have any occasion to want a proportional divider, you shouldn't go wrong buying this one. They aren't making them anymore and are only going to become increasingly valuable as time goes on.

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Agreed that the price isn't too bad.  I saw the same proportional divider listed on ebay a few weeks ago for 89.99.  It was sold within a few hours.  This posting has been up for at least three weeks so perhaps there is room for negotiation.

 

It's too bad about the divider, not only are they handy but the rest of the set and the case look to be in great condition considering.

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I too use proportional dividers but how can they be used for planking on a model?  The frames are curved so if you take a measurement on the frame it will be incorrect.  Dividers only work in straight lines as I understand it so they are great for working on plans but not 3D models.  Paper and a calculator are required which makes the dividers redundant.  Great bits of kit but seldom used in my very limited experience.  

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6 hours ago, No Idea said:

I too use proportional dividers but how can they be used for planking on a model?  The frames are curved so if you take a measurement on the frame it will be incorrect.  Dividers only work in straight lines as I understand it so they are great for working on plans but not 3D models.  Paper and a calculator are required which makes the dividers redundant.  Great bits of kit but seldom used in my very limited experience.  

The procedure is very simple  using a "tick strip." You take a strip of paper... (teletype "punch tape" or "ticker tape" used to be great for the purpose, but it's gone the way of the button hook these days) ... and lay it against the curved frame and mark ("make a tick") the lowest and highest points of the planking section on the tape. Then lay the tape flat and with your proportional dividers set to yield the number of plank seam divisions you require, you take up the overall length of the frame face from the tick strip with the "long legs" of your dividers. The opposite "short legs" of your dividers will yield the distance of equal plank widths on that frame length. Mark the frame lengths on your tick strip. Then take the tick strip and again position it on the frame face with the tick marks at the ends at the ends of the section of frame you want to lay out plank spacing for and transfer the rest of the tick marks to the frame face. Repeat for as many frames as you wish to divide. It's much faster than using a calculator and there's less opportunity for error because the proportional dividers require no calculation and the accuracy of the divisions yielded are easily checked by simply "walking" the points down the length of the distance to be divided. If the number of "steps" on the line ends with the point right on the last "tick" after taking the number of "steps" you desired, you know you haven't made any mistake in taking the original overall measurement.

 

 

Edited by Bob Cleek
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Seems overkill using dividers to make the planking tic strip.    Just print one out from MSW and use that.  Or am I missing something?

Mark
"The shipwright is slow, but the wood is patient." - me

Current Build:                                                                                             
Past Builds:
 La Belle Poule 1765 - French Frigate from ANCRE plans - ON HOLD           Triton Cross-Section   

 NRG Hallf Hull Planking Kit                                                                            HMS Sphinx 1775 - Vanguard Models - 1:64               

 

Non-Ship Model:                                                                                         On hold, maybe forever:           

CH-53 Sikorsky - 1:48 - Revell - Completed                                                   Licorne - 1755 from Hahn Plans (Scratch) Version 2.0 (Abandoned)         

         

                                                                                                                                                                                                                                                                                                

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16 hours ago, Bob Cleek said:

The procedure is very simple  using a "tick strip." You take a strip of paper... (teletype "punch tape" or "ticker tape" used to be great for the purpose, but it's gone the way of the button hook these days) ... and lay it against the curved frame and mark ("make a tick") the lowest and highest points of the planking section on the tape. Then lay the tape flat and with your proportional dividers set to yield the number of plank seam divisions you require, you take up the overall length of the frame face from the tick strip with the "long legs" of your dividers. The opposite "short legs" of your dividers will yield the distance of equal plank widths on that frame length. Mark the frame lengths on your tick strip. Then take the tick strip and again position it on the frame face with the tick marks at the ends at the ends of the section of frame you want to lay out plank spacing for and transfer the rest of the tick marks to the frame face. Repeat for as many frames as you wish to divide. It's much faster than using a calculator and there's less opportunity for error because the proportional dividers require no calculation and the accuracy of the divisions yielded are easily checked by simply "walking" the points down the length of the distance to be divided. If the number of "steps" on the line ends with the point right on the last "tick" after taking the number of "steps" you desired, you know you haven't made any mistake in taking the original overall measurement.

 

 

Hi Bob this is what I meant but you are better with words than me.  If you use a piece of paper to measure the distance due to a curve then a calculator is or planking fan I think should be your next stop for planking.

 

15 hours ago, mtaylor said:

Seems overkill using dividers to make the planking tic strip.    Just print one out from MSW and use that.  Or am I missing something?

This is my opinion too for what its worth.  A simple job that can become very overcomplicated when there is a very simple solution as you have suggested. 

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22 hours ago, mtaylor said:

Seems overkill using dividers to make the planking tic strip.    Just print one out from MSW and use that.  Or am I missing something?

No reason not to. There's more than one way to skin a cat. The handiest use I get out of proportional dividers is scaling drawings up and down. That, too, can be done with a copier, but often it's only small sections of a drawing that need to be redrawn which don't justify copying the often very large drawings encountered at 1:48 scale. 

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7 hours ago, No Idea said:

Hi Bob this is what I meant but you are better with words than me.  If you use a piece of paper to measure the distance due to a curve then a calculator is or planking fan I think should be your next stop for planking.

 

This is my opinion too for what its worth.  A simple job that can become very overcomplicated when there is a very simple solution as you have suggested. 

 

Those options are also available. It's a matter of preference. I prefer a mechanical transfer of measurements because there is less opportunity for error and less thinking that has to go into it. With a mechanical measurement, any error is immediately apparent by a simple visual comparison, as well. At the end of the day, though, it boils down to what one is used to doing. Manual drafting is a skill I picked up when I was a kid in high school and, while I'm not anything near a professional draftsman, it's always been a quick and comfortable way to do the job for me. I've amassed a considerable collection of drafting instruments over the years just for the enjoyment of it. I have complete sets of Copenhagen ships curves, French curves, engineering curves, and "railroad" and "highway" curves (which have fixed radii.) I use the railroad curves for drawing deck and cabin top cambers conveniently, not often, but I've got them when I do. Similarly, I have an Omicron ellipsograph, which draws elipses to measured dimensions. I've only used it once or twice, but if I ever have to draw an elliptical stern, I'm good to go. :D 

 

deliveryService?id=NMAH-DOR2013-00709&max=1000

https://americanhistory.si.edu/collections/search/object/nmah_904482

 

I have a couple of different "dotting pens," which will draw inked dotted and dashed lines in a variety of configurations. One can draw dots and dashes along a rule easily enough, but the elegance of the tools devised a century or more ago to do the job is fascinating.

 

747197_81_73928_vHVZzusGU.png

https://americanhistory.si.edu/collections/search/object/nmah_904301

 

 

I've also got a compensating polar planimeter which measures the area of irregular planes. A planimeter is used to calculate hull displacement, sail area, wetted surface, and things like that from lines drawings. Not something the average modeler would ever need to have, but it's another fun old instrument rendered obsolete by CAD these days which can be picked up for fifty bucks or less on eBay if one is so inclined. 

 

Image 1 - 1970-039-s-Vintage-Keuffel-amp-Esser-K-amp-E-Polar-Planimeter-620015-serial-number-22647

https://americanhistory.si.edu/collections/search/object/nmah_1214998

 

If one is a kit builder, or limits their scratch-building to plans drawn for modeling, most of this stuff is probably of little interest, but for anyone who finds it necessary to draw their own plans for modeling purposes, some of it can be very handy, albeit on rare occasions. For myself, it's mainly just an affordable outlet for my innate acquisitiveness... just another thing to collect. 

Edited by Bob Cleek
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I have recently been studying Seventeenth Century (1600’s) ship design techniques.  Those guys developed interesting methods for graphically plotting the large radius circles and the ellipses necessary to draw the hull forms of this time.  All were based on first drawing a smaller diameter circle and “stretching it out.” 

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  • 5 weeks later...
On 3/15/2021 at 5:13 PM, Roger Pellett said:

I have recently been studying Seventeenth Century (1600’s) ship design techniques.  Those guys developed interesting methods for graphically plotting the large radius circles and the ellipses necessary to draw the hull forms of this time.  All were based on first drawing a smaller diameter circle and “stretching it out.” 

If you have the time, it would be interesting to see how they did that!

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