Calculate mandrel size for spring winding

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kquiggle

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This post is partly a call for "testers" : I have created a spreadsheet to calculate the mandrel diameter needed to wind a spring of specified diameter and wire type. The spreadsheet is based on Design and Wind Your Helical Springs by Kozo Hiraoko (Part 1 page 20 Home Shop Machinist 1987 May-Jun, part 2 page 30 Home Shop Machinist 1987 Jul-Aug). I believe the spreadsheet is correct, but I am requesting the following:


  1. Try the link below - make sure you can access and use the spreadsheet
  2. If possible, verify that the spreadsheet results conform to your own experience in spring making
  3. I based the spreadsheet on a not very good copy of the article cited - if anyone can provide me with a high resolution copy of the article (or even just the graph for finding k value), I would appreciate it.
Comments, suggestions, criticisms, and observations are welcomed!

Here is the link to the spreadsheet and related information:

https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/tools---spring-making
 

Jeff Lott

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Information is also available in the Machinery Handbook if you have one.
 

kquiggle

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Jeff - thanks for tip.

As a matter of fact, I do have an older copy of Machinery's Handbook (9th edition), but it didn't occur to me to look in it! Now that I have, here is what I found:

There is a table of "Data for Winding Piano Wire Tension Springs" for piano wire of English gage numbers 1 to 36 (diameters 0.0098" to 0.118"). for about 100 different spring diameters. This is of course more limited than a spreadsheet which can accept any number of values, although I suppose one could interpolate values in the table to come up with additional values. The only table is for music wire (according to Hiraoko stainless steel wire should be the same), but there is nothing for phosphor bronze wire.

I used the handbook table to plug some numbers into my spreadsheet - there seemed to be good agreement with some deviations. I'll make some additional checks as time permits and report the results back here.

P.S.

I check a friend's newer handbook (28th edition) - it has a more readable table of "Arbor Diameters for Springs Made from Music Wire" - looks quite useful, I will use that table to check my spreadsheet.

Always good to have more information - thanks again.
 

rklopp

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The spreadsheet seems pretty accurate based on one observation of mine. I wound 30 valve springs from 0.022" music wire on a 0.155"-dia mandrel, and ended up with 0.188" ID. The spreadsheet says the mandrel should be 0.158" for a 0.188" ID, so not bad at all.
 

kquiggle

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rklopp - thanks for the confirmation.

Sounds like you might have been winding those springs for a Webster or similar. I'm currently working on a Webster and getting ready to make springs for it, which is why I got into this spreadsheet in the first place.

I'm currently working on adding more capabilities to the spreadsheet. Among other things, I have added data from Machinery's Handbook 28th Ed. and compared that data to the spreadsheet calculations - the agreement is generally pretty good (often exactly the same), although there are some interesting differences. I'll be posting the updated spreadsheet soon.

By the way, if anyone reading this would like to see some particular feature added to the spreadsheet, post your suggestion here and I will consider it.
 

rklopp

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My springs were for a set of six modified Upshur Twins I have been whittling away at for quite a while. I'm getting close. The parts count gets high when you have 6 engines x 2 cylinders x 2 valve trains.
 

tornitore45

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The spreadsheet can not be downloaded in *.xlsx format.
If you want help you need to make the file available.
 

kquiggle

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kquiggle

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I'm working on Version 3 of my spring calculations spreadsheet, and before I complete this version I would like to check my assumptions.

In Version 3 I am adding a calculation for "equivalent springs." For example, suppose you have a plan which calls for a spring made from 0.022" wire, and all you have is 0.025" wire - how do you make an equivalent spring out of a different wire diameter? My assumption is that if you make a spring with the same spring rate as the "original" it should be an acceptable substitute.

My "equivalent spring" calculation allows you to enter the various parameters for an "original" spring (wire diameter, number of coils, spring diameter, etc.) and then generate the parameters for an equivalent spring by entering all but one of the parameters and then calculating the remaining parameter.

So in my example above, when changing the wire diameter, you could calculate the number of coils you would need for an equivalent spring.

Is my assumption above correct?
 

tornitore45

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kquiggle I retract my snappy comment since the spreadsheet was not locked intentionally.
 

kquiggle

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No problem Mauro - I was glad to know about the problem so I could fix it.
 

gus

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Hi Kquiggle,

Info very useful. Did not realise it exist in Machinery HandBook. Been trying on and on DIY making springs with erratic results. May DIY a Spring Making Device as per Tubal Cain's Book----
Spring Design and Manufacture when time and urgent requirement happened. Meanwhile been taking from ''' Assorted Springs''' Box from China for IC engines. So far so good.
 

kquiggle

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Gus -

I have only made a couple of springs but I have had good results. Below is a link to more information - includes a link to an interesting hand winder for springs which I am tempted to make (it's essentially a hand-wind operation on the lathe anyway).

Click on the link and scroll down to "Springs":

https://sites.google.com/site/lagadoacademy/useful-links#tipsandtricks

P.S.

I have almost completed the final version of my spreadsheet. Mostly I just need to proof read it one last time, but I had to set it aside for a bit due to temporary "spring fever."
 

kquiggle

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Well, it took a bit longer that I planned but I finally finished Version 3 of my spreadsheet for making spring calculations. This will be the final version unless any errors crop up which need to be corrected.

The spreadsheet offers three options:

  1. Mandrel: Calculate the mandrel size needed to wind a spring of a specified diameter.
  2. Equivalent: Given a set of spring parameters, find the parameters for a spring with the same spring rate but with a different wire size, diameter, number of coils, etc.
  3. Table: A simple lookup table to find arbor (mandrel) diameters for winding music wire springs of a designated size.
Option 2 is useful when you want to make a spring designated in a plan, but you only have spring wire approximately equal to the size specified in the plans.


Option 3, in theory, would give the same results as Option 1, but in testing I have sometimes found small differences. My guess is that the table probably is more accurate for large lathes in a production set up, and that Option 1 is more accurate for small lathes in a hobby set-up (but this is purely a guess).


I have tested the spreadsheet as best I can, and I believe it to be free of any errors, but of course I cannot guarantee this; if anyone else tries it out and finds a problem (and lets me know!), I will make the necessary corrections.



You can download the spreadsheet in LibreOffice and Excel versions here:


https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/tools---spring-making?pli=1
 

Gerhardvienna

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Hi kquiggle
Just downloaded both , the spreadsheet and the educypedia, this will help a lot!
Thanks for "delivering" that!:D
Regards
Gerhard
 

SwarfMuncher

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I know this is an old thread, but your spreadsheet is just what I was looking for! I am winding 2-coil torsion springs from music wire, and the spring must fit inside the device in which it is used, so there is a machined circular slot to accommodate it. My first attempt using 0.062" music wire fit OK, but is not providing enough spring action.

So to increase to 0.091" wire, I am finding the "spring back" after winding on my lathe (by hand crank) is increasing the finished spring coil diameter too large to fit. I've been guessing at mandrel size. This sheet will help me home in on the correct diameter.

THANKS!!

:thumbup:
 

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