Thin kerf knot

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DavidSpavin

DavidSpavin

Member
Joined
Jul 13, 2007
Messages
107
Location
Norfolk, United Kingdom.
After a request from GaryMGg here are a few notes on how I created this pen.
tn_PauAmerelo01.jpg

I don't own a table saw so all the cuts are done on a band saw. I made a simple sliding table with a jig to hold the blank.


20071011195744_JIG.jpg


I don't cut all the way through the blank only about 90% of the way (a method I saw else where on this forum, cann't find it again though :()Then its just a matter of gluing the correct size of inlay in.
I did spend several weeks trying to match the kerf (0.635mm) of the band saw blade. The only method I found was to cut veneers as thin as I dare and then use a cabinet scraper to reduce the thickness (and remove the marks from the blade) How ever I had an inspirational moment last week, did a bit of reserch on the internet and found company selling wood veneer offcuts with a thickness of 0.6mm, I bought a pack and ,as the saying goes, the rest is history.
I hope the above makes sense, If (k)not please ask questions.
 
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Thanks for posting this. I have a been thinking of using my bandsaw but all of the blades that I have on hand here do not give a very smooth cut. If I were back in the States, I would probably get a couple of timberwolf blades.
 
I was going to comment a day or two ago in your other knot thread but got sidetracked and forgot so will do it here. Great pen, Dave!! I love the dimensions of your knot. For my taste(and I realize that people's tastes differ) most of the knot pens have a knot with layers that are much too thick and just don't seem to fit with the overall scale of the pen. The knots seem to overwhelm the pens. Your thinner kerf appears ideal to me and I really admire the layered effect in the other pen.

If you would like a bit of a challenge, below is a picture of a knot that I think has wonderful form and configuration but is perhaps a bit too thick in the layers. Do you feel up to trying something like this. The angles are a little different and if I counted correctly, there are 6 rings instead of 4 which will be a little tricky; but I think the final effect would be wonderful.

The picture is of a pen that was made by Ron in Drums PA. I bet he would be willing to offer a tip or two if you needed some guidance.



2007101283941_RonsCelticCross.jpg
 
I assume to get a six loop knot you would have to start with a hexagonal blank instead of a square one. As for the different angle I will try some thing this week end and post the results.
 
Originally posted by DavidSpavin

I assume to get a six loop knot you would have to start with a hexagonal blank instead of a square one. As for the different angle I will try some thing this week end and post the results.
Click to expand...

David,

This pen and instructional article was included in the recent issue of Woodturning Design magazine. He started with a round blank. Good article.

http://www.woodturningdesign.com/issues/current.shtml

Thanks for sharing your sled picture. Guess I will be doing some flat work this weekend to make one for myself.

Tim
 
Unfortunately, it appears you cannot access the specific article at the link posted above....only see a picture of the magazine cover. Apparently you have to purchase a copy of the magazine, which, I guess, is as it should be.
 
Ok Eric just for you. I took a series of picks of a pen I made over the weekend. The knots are at 22.5 degrees instead of the usual 45 degrees. Hope they are of use to you and anyone else interested.


Start with a square blank
20071015184741_Proj01Blank.jpg



The jig
2007101518481_Proj02Jig.jpg



Mark the center of the knots
20071015184819_Proj03Marking.jpg



The first cut
20071015184838_Proj04FirstCut.jpg



Using a block to off set for the second knot
20071015184858_Proj05SecondCut.jpg



The completed cuts
20071015184910_Proj06Cuts.jpg




Glued up (I use Polyurethane)
20071015184949_Proj08Glued.jpg



Use a clamp to stop the expanding glue distorting the blank
20071015185012_Proj09Clamped.jpg



The inlays after a cleanup
20071015185030_Proj10Cleaned.jpg



The second set of cuts
20071015185049_Proj11SecondFace.jpg



All the cuts finished (Sorry about the focus)
2007101518516_Proj12InlaysFinished.jpg



Cut the blank to length
20071015185219_Proj13CutToLength.jpg



Drilling on the lathe to ensure the hole is central.
2007101518535_Proj14DrillOnLathe.jpg



Glue in the tubes
20071015185334_Proj15Tubes.jpg



Mounted ready to turn
20071015185351_Proj16ReadytoTurm.jpg



Turned and sanded ready for the finish
2007101518549_Proj17ReadytoFinish.jpg



The finished pen
20071015185431_Proj18Finished.jpg



A close up
20071015185445_Proj19CloseUp.jpg
 
Very nice concept, Dave. I don't recall that anyone has done a "compressed" knot before??

I wonder if you are messing with our minds a little? The knots appear to be much farther apart on the finished pen than they are on the blank you show in the photos of preparation.

I would like to see a pen where the distance between the two knots was the same as the width of the knot.
 
Originally posted by Randy_

Unfortunately, it appears you cannot access the specific article at the link posted above....only see a picture of the magazine cover. Apparently you have to purchase a copy of the magazine, which, I guess, is as it should be.
Click to expand...

To buy a single copy of the magazine from the Internet will cost you $6.49 plus $3 for shipping and handling. Yikes, pretty pricey!!

You can have a full years subscription(4 issues) for $19.97. They sort of have you by the @#$%s. Pretty obvious which way to go!

Think I will do the same thing I have done in the past and offer the magazines to someone here at IAP who is willing to make a small donation to IAP.
 
Originally posted by Randy_

I wonder if you are messing with our minds a little? The knots appear to be much farther apart on the finished pen than they are on the blank you show in the photos of preparation.
Click to expand...

The simple reason for the apparent change in separation is the finished pen has a smaller diameter than the blank, so the knot shrinks making the separation greater. (If that makes sense !)
I was thinking the next one would have 3 knots, which should balance the design better.
 
Originally posted by DavidSpavin

The simple reason for the apparent change in separation is the finished pen has a smaller diameter than the blank, so the knot shrinks making the separation greater. (If that makes sense !)
I was thinking the next one would have 3 knots, which should balance the design better.
Click to expand...

Yeah, that makes perfect sense. Just didn't think about it carefully enough. Nonetheless, I think the pattern would look better if the knots were closer together. Given your construction parameters, it may not be possible to achieve the suggested spacing. I will play with my CAD program a little and see what is possible. Out of curiosity, what size blank do you start with? Thanks.
 
Hey David, you certainly have the knack of the 'cross'. Every one that I have seen is bang on!!! Well done. I look forward to meeting you at our next meet up. :D
 
200710166324_PenClamp.jpg



Dave: That is an interesting clamp. Don't think I have ever seen anything like it before. Maybe they aren't sold on this side of the pond. Do you know the name of the manufacturer?? Thanks.
 
Originally posted by Randy_


Dave: That is an interesting clamp. Don't think I have ever seen anything like it before. Maybe they aren't sold on this side of the pond. Do you know the name of the manufacturer?? Thanks.
Click to expand...
They are called solo clamps try here for a stockist in the US http://cox-applicators.com/index.php/our-products/?category=4
The UK manufacturer is here:-
http://www.pccox.co.uk/14.0.html?&tx_pwpccox
Code: 
=displayRange&tx_pwpccox[uid]=5
The blank is 20x20x150mm
 
Originally posted by Randy_


I wonder if you are messing with our minds a little? The knots appear to be much farther apart on the finished pen than they are on the blank you show in the photos of preparation.
.
Click to expand...
After a quick number crunching session I have come up with the following:-
Assuming starting with a 20mm blank and ending with a 10mm diameter pen.
For a knot of angle 65deg the increase in separation is 4.7 mm
at 45 degrees it is 10mm and at 22.5 deg the increase is 24mm.
Quite dramatic when the angle gets small.
The equation ended up as:-
Increase in separation =(Blank size - pen diameter)/tan(angle)
 
Originally posted by DavidSpavin

After a quick number crunching session I have come up with the following:-
Assuming starting with a 20mm blank and ending with a 10mm diameter pen.
For a knot of angle 65deg the increase in separation is 4.7 mm
at 45 degrees it is 10mm and at 22.5 deg the increase is 24mm.
Quite dramatic when the angle gets small.
The equation ended up as:-
Increase in separation =(Blank size - pen diameter)/tan(angle)
Click to expand...


David: I think your equation is correct; but I don't come out with the same results as those you posted. I think you may have the 22.5° result and the 65° result reversed and it looks like there might be a typo in the 22.5° result....should it be 4.17 rather than 4.7? I also wonder about the 65° result. That looks like it might be the 67.5° solution rather than the one for 65°?

BTW, thanks for the information on those clamps. They look like they would be very handy. Think I will try to find a source here in the States and see if I can pick up a few.
 
Originally posted by Randy_

Originally posted by DavidSpavin

After a quick number crunching session I have come up with the following:-
Assuming starting with a 20mm blank and ending with a 10mm diameter pen.
For a knot of angle 65deg the increase in separation is 4.7 mm
at 45 degrees it is 10mm and at 22.5 deg the increase is 24mm.
Quite dramatic when the angle gets small.
The equation ended up as:-
Increase in separation =(Blank size - pen diameter)/tan(angle)
Click to expand...


David: I think your equation is correct; but I don't come out with the same results as those you posted. I think you may have the 22.5° result and the 65° result reversed and it looks like there might be a typo in the 22.5° result....should it be 4.17 rather than 4.7? I also wonder about the 65° result. That looks like it might be the 67.5° solution rather than the one for 65°?

BTW, thanks for the information on those clamps. They look like they would be very handy. Think I will try to find a source here in the States and see if I can pick up a few.
Click to expand...
Just checked my results and I get
65° = 4.663076582 (4.7)
45° = 10.00
22.5° = 24.14213562 (24.0)

I think you and I are measuring the angle differently. I use the angle between the side of the blank and the axis of the blade. I think you are using the angle between the blank and a line perpendicular to the blade.
My angle of 22.5° gives me the narrow knot and 65° the open knot, in what I think is you way it would be reversed. The way I measure the angle comes from the jig I use and represents the angle the jig is cut.
Hope this explains our differing results.
 
Originally posted by DavidSpavin

.....I think you and I are measuring the angle differently. I use the angle between the side of the blank and the axis of the blade. I think you are using the angle between the blank and a line perpendicular to the blade.
My angle of 22.5° gives me the narrow knot and 65° the open knot, in what I think is you way it would be reversed. The way I measure the angle comes from the jig I use and represents the angle the jig is cut......
Click to expand...

Knot( :D ) sure I understand your written definition of the angles so let's make it easy for me.

According to your earlier posts, this is a 65° pen:
2007101719629_Celtic_65Deg.jpg



and this is a 22.5°:
2007101719745_Celtic_22point5.jpg



Are we agreed on that point or not?? (The way I think of the angle is it is the angle you would have to set on the miter gauge of a saw if you were making a cut.)

Given that we are agreed on the way the angle is measured, I think the equation for figuring the separation should be: Separation = (Blank thickness-Pen dia.) x tan(angle).

(Note: Earlier, I commented that your equation was correct; but I misread it and now think it is not.)
 
Originally posted by Randy_


Given that we are agreed on the way the angle is measured, I think the equation for figuring the separation should be: Separation = (Blank thickness-Pen dia.) x tan(angle).

(Note: Earlier, I commented that your equation was correct; but I misread it and now think it is not.)
Click to expand...
You are right. Now I have seen the two pens together it is obvious the '65°' knot is going to shrink faster than the '22.5°' knot as the diameter of the blank decreases. I should have checked my results and applied common sense before posting[:I]:(
 
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