Bandsaw Blade Tension

[Martin CargillParticipant @martincargill50290]

Has anyone come across a blade tension guide? I have a blade tension gauge for bandsaws. It works by measuring how much stretch the tensioning system puts on a blade. To then work out how much tension is being put onto the blade you then need to make a calculation based on the cross sectional area of the blade.

Surely someone must have compiled a chart that shows all of the common sizes of blades and their relative elongations to ensure correct tensions.

I know that some machines (especially wood machines) simply state to apply as much tension as is required to cut a straight line, but, with metalworking machines this is more difficult to achieve.

There must be a chart somewhere but I cant find one.

Martin

[Martin CargillParticipant @martincargill50290]

[Brian WoodParticipant @brianwood45127]

Martin,

I have successfully used a musical note approach for years, but don't ask me what sort of frequency I choose, it is well above a dull thud to something a lot more pleasing.

If that is any kind of guide for you it might save you some angst and cost!

Regards Brian

[Martin CargillParticipant @martincargill50290]

Brian. Thanks for your input, I have used a similar method in the past but I deal with a range of machines using blades from 1/4" to 6" wide,on this range of sizes trying to achieve the right tension by ear is difficult.

Martin

[John HinkleyParticipant @johnhinkley26699]

Graham Meek showed a photo of his blade tension setting device In this thread. I don't know if its construction is described in MEW or another publication; perhaps Graham will see this and point us in the right direction.

John

[Brian WoodParticipant @brianwood45127]

Martin,

I see your problem although to be frank, I imagine getting blade tension on blades of 6 inch depth or so is more a question of trying to get enough!

Brian

[Howard LewisParticipant @howardlewis46836]

Jacques Maurel produced a design for Tension Meter, and has, fairly recently, shown his calculations in MEW.

From memory, the standard 64" x 1/2" x 0.020" blade in the generic 4 1/2" bandsaw, needs something like 0.05 – 0.07 mm extension to achieve the correct bvtension.

A correctly tensioned blade, in a fairly well set up bandsaw produces more accurately, and blade life is extended in my experience.

Howard

[John HinkleyParticipant @johnhinkley26699]

Did a bit more digging and, as Howard says, Jacques Maurel produced a gesign for such an animal. It was apparently described in Engineering in Miniature (June 2016) as referenced in this thread on the mig-welding web site.

John

[Howard LewisParticipant @howardlewis46836]

More recently, in MEW 319, September 2022, GarWooding decribes making a tension meter to J M's design.

In Scribe a Line in MEW 320, October 2022, Jacques Maurel shows hIs calculations for arriving at the extension required to apply the correct tension to the blade.

Howard

[Martin CargillParticipant @martincargill50290]

I already have a blade tension gauge. It could probably be described as a "stretchometer". But the blade stretch varies depending on the width and depth of the blade. To avoid having to do a calculation for each blade size I was looking for a table covering the standard blade sizes, perhaps such an animal soes not exist.

Martin

[Howard LewisParticipant @howardlewis46836]

I fear not! Not many people have Tension Meters, so with little demand, no one has done trhe calculations.

The calculations are shown in Jacque's letter to Scribe a Line in MEW 220, so unfortunately, you will need to work from there, for each size of blade..

Howard

[DiogenesIIParticipant @diogenesii]

Martin Kennedy published words, music, sums and calculator in the newsletters of Houston's Home Metal Shop Club starting in Vol 16 no 8;

HMSC – August 2011 – Setting Tension ina Bandsaw Blade

..and revisited the subject in 2020

HMSC -Sep 2020 – ..Tension in a Bandasw Blade Revisited

I'll leave you to peruse them and see if it's helpful..

[Martin CargillParticipant @martincargill50290]

Thank you all for your input. It looks like I'm going to do some calculations to work out blade tensions.

One thing I can't work out is that the videos and photos of the Lenox gauges show them with yellow/green/red segments on the gauge face – surely the tension must change with the dimensions of the blade, yet their gauge does not allow for this, unless they have specific gauges for specific blade sizes?

Martin

[Mark RandParticipant @markrand96270]

It strikes me that a band with a larger cross section will need a higher tension. Maybe even to the extent that one would want exactly the same strain (percentage extension) for any blade, no matter what its size was…

 

What's the problem?

Edited By Mark Rand on 31/08/2023 20:47:51

[Martin CargillParticipant @martincargill50290]

Mark.

I hadn't thought of it in those terms, I think you're right, I was misled by some articles that I found where the blade cross section was taken into account during the calculations. This explains the markings on the Lenox gauges.

Martin

[Dave HalfordParticipant @davehalford22513]

Posted by Howard Lewis on 31/08/2023 14:53:41:

Jacques Maurel produced a design for Tension Meter, and has, fairly recently, shown his calculations in MEW.

From memory, the standard 64" x 1/2" x 0.020" blade in the generic 4 1/2" bandsaw, needs something like 0.05 – 0.07 mm extension to achieve the correct bvtension.

A correctly tensioned blade, in a fairly well set up bandsaw produces more accurately, and blade life is extended in my experience.

Howard

If as Howard says the tension is set by elongation of the blade why would a broader blade need more elongation to have the correct tension? Steel will only stretch so far regardless of cross section so though it will take more force to produce required extension the 0.05 to 0.07mm is still valid.

[jacques maurelParticipant @jacquesmaurel42310]

Hello
Thank you for your interest in my articles about bansaw blade tensioning. Here are the ref for my articles about this subject :

Engineering in miniature june 2016 issue: A tensiometer for a bandsaw blade.

Engineering in miniature march 2017 issue: A spring tensioner for a bandsaw blade.

Notes:
The tensiometer works for any blade section, but you must tension from the slackened state and you don’t know the actual tension when time lasts.
The spring tensioner must be dedicated to the blade section, but you know the actual tension in the blade.

A related article: for hacksaw blade tensioning:

Engineering in miniature october 2018 issue: Improving a hacksaw.

A related article about bansaws:

Engineering in miniature december 2014 issue: Magic stick for bandsaw alignment.

To know all my publications, go to my website :
**LINK**

[bernard towersParticipant @bernardtowers37738]

Interesting to know that I am not the only one who looks at HMSC's site it has some interesting stuff.

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