Kerf Spacing Calculator for Bending Wood

[Blocklayer]

I've just added a Kerf Spacing Calculator to blocklayer.com, that some of you may find useful.
It works out the geometric spacing of the cuts so when bent, the inside edges of the cuts join to create the curve.
The depth of the cuts (and remaining wood thickness for the bend) can't be calculated (that I can work out anyway). That seems to be the art of it. Depends on the wood and the dimensions. Trial and error?
But this will produce simple geometric diagrams, so you can see the wood and cuts both straight and bent, and drag sliders to animate angle, radius, cut width etc to see what changes.
It also creates a full scale template to mark out the cuts.
https://www.blocklayer.com/kerf-spacingeng.aspx
It obviously can't be 100% accurate, but should give a pretty close idea of what sort of a bend you'll get for the entered dimensions.
If it needs editing, additions, fixing or you have any other ideas for improvements, please let me know.

[Cal]

Wow!  Welcome aboard Blocklayer, that is quite a gift that you bring with your first post.

If it were up to me, I would excuse you from bringing donuts; but, alas - it is not.  Forum etiquette dictates the newbie brings 'em - lots of them...

 

Seriously good info though,

Cal

[Grandpadave52]

Welcome @Blocklayer to TPW...great to have you here...Ironic, I visited your site just a couple days ago. It was linked in a You-Tube video I watched re: building gambrel roof trusses. Most excellent information available there. Thanks.

 

However, it is the protocol all new members furnish donuts...Your turn is today...make mine chocolate iced, chocolate please...Hope to see more posts and sharing of your talents and knowledge here!

[lew]

Thanks!!!!!!!!!!!!

[Gene Howe]

Welcome, Greg. Glad to have you aboard.

[Stick486]

great opening entry Greg...

thanks and welcome to the TPW......

but where's the donuts...

[Al B]

MAN !!! That's amazing. Maybe these guys can figure out how to make the worlds biggest donut using your kerf spacing calculator. Welcome to the PW

[schnewj]

Welcome Greg, I'm still exploring some of your links that Dave posted the other day...

 

Glad you could join the fun...but, alas, you need to bring doughnuts to the party...but, since there are a bunch of doughnut hogs here, and I seem to be the one always late to the party, I'll settle for a piece of Deep Dish Apple pie...and since you brought your excellent calculators, I'll let you slide on the Vanilla ice cream.

 

Bill

[Blocklayer]

Thanks all.

Not sure what this doughnut thing is all about, but I've managed to obtain a few to distribute amongst forum members.

 

Get your doughnuts here

 

But be quick, they may not last long.

Edited October 15, 2017 by Blocklayer

[Stick486]

actually doing something for the donuts...

how cool is that...

[schnewj]

Good one, Greg.

 

You've got a good sense of humor...we just may keep you around...

[Smitty]

Could you tell me what cuts I would need to bend 3/4" pine shiplap seven feet three inches long with a one foot depth. Like a bow for a bow and arrow. I understand I'd have to workout the depth of the cuts, but how many and how far apart would they need to be? Thank Mike

 

[Ron Dudelston]

Mike, first of all, welcome to the site.  How tall is the piece that you want to bend?  I’ve not bent shiplap but I bent a piece of 3/4 plywood that was 7” tall.  I cut the kerfs at 3/4” apart.

[Cliff]

On 10/10/2017 at 1:32 AM, Blocklayer said:

https://www.blocklayer.com/kerf-spacingeng.aspx

that's real interesting.  It is trying to give you a completely  closed kerf,  blades can't be under .1

I input to get a 6" radius and it only wanted 10 cuts.  if I wanted a more round-ish exterior I'd use more than that.

I thought I was missing depth of cut  but they  use the opposite  referring to the wood remaining after the kerf cut.  Min Thickness

[lopickett]

Hey BlockLayer,

 

I am a new woodworker and also failed geometry student haha.  So it would be awesome if you had some sort of documentation explaining what all of the terms are for the calculator and mayube even a simple youtube tutorial walking through the process.  That would be awesome!  I cant find any information on how to really use it correctly!

[lew]

37 minutes ago, lopickett said:

Hey BlockLayer,

 

I am a new woodworker and also failed geometry student haha.  So it would be awesome if you had some sort of documentation explaining what all of the terms are for the calculator and mayube even a simple youtube tutorial walking through the process.  That would be awesome!  I cant find any information on how to really use it correctly!

You can use the calculator in two different ways.

1. You can enter the values of your dimensions directly in the boxes (radius, angle, kerf, etc) on the left side of the page and then calculate. The board graphic will display what it will look like.

 

2. You can drag the blue sliders to change some of the dimensions to quickly see what the differences will be. 

 

As for term meanings-

Curve radius- half the diameter of the bend if it was bent around a circle

Sweep Angle- the angle formed between the starting a nd stopping point of the bend

Kerf- thickness of the saw blade

Wood thickness- how thick is the piece you are going to bend

Minimum thickness- how much wood is left between the outer edge and the wood removed by the saw blade.

 

A 72" diameter circle, 36" radius, 90° sweep angle-

[FlGatorwood]

Wow! Most of the original posters no longer frequent this site.  And, I missed this post all these years.  Thanks for reviving it.  I have a church window to rework and I need to know how to bend a 2" X 10" to fit back in.  It is holding a stained glass window made by a sister-in-law.  We don't want to loose any of it.  

[lopickett]

@lew Thank you so much for the info!  This is extremely helpful.  I probably would have spent a super long time figuring all of this out and would end up pretty frustrated hahaha.  You saved me a whole lot of time.

[lew]

27 minutes ago, lopickett said:

@lew Thank you so much for the info!  This is extremely helpful.  I probably would have spent a super long time figuring all of this out and would end up pretty frustrated hahaha.  You saved me a whole lot of time.

Not a problem! Hoping to see some of your woodworking projects posted.

[joemamma]

On 12/13/2020 at 10:37 AM, Cliff said:

that's real interesting.  It is trying to give you a completely  closed kerf,  blades can't be under .1

I input to get a 6" radius and it only wanted 10 cuts.  if I wanted a more round-ish exterior I'd use more than that.

I thought I was missing depth of cut  but they  use the opposite  referring to the wood remaining after the kerf cut.  Min Thickness

My Diablo 60T finishing blade from Home Depot is only .059 and cuts .0625 after accounting for wobble, vibrations, etc.
It's definitely possible to get under .1" out of a blade