Varying Radius When Cutting With Flying Dutchman Superior Puzzle Blade Issue

[Gordon Wu]

New to cutting with a scroll saw.  I've had about maybe 15-20 hours total on the scroll saw.  Cut a couple of small christmas cards into puzzles using the Flying Dutchman Superior Puzzle blade on 1/4" baltic birch.  One thing I have a hard time controlling and it seems to vary from blade to blade is the radius of my cuts.  There are some blades I can cut a very small radius at first...then the radius gets really big or I can see the blade clearly not pointed straight...like it's bent 45 degrees or more to the side.  And it is almost always when i'm rotating the wood clockwise.  

 

You can see in the picture in the attached image with the measuring tape that there's a top piece with a really big radius in the cut.  Then the same piece got a lot smaller radius in the cuts.  Is that just bad technique?  Or is it easier to cut when turning counter clockwise because the left side of the blade is sharper for some reason?  Is it okay when the blade is bending 45 degrees?  

 

Is there a general rule on the minimum radius for a cut vs the width of the blade or wood hardness/thickness?  Am I simply cutting my pieces smaller than I should?  

 

I've read the thread about 5 and 10 reasons for broken blades...for the life of me, I can't seem to tell if the tension is too tight...hard to tell.  I'm using a Hegner scroll saw and I'm adjusting the tension with the knob in the back...any clue if 2 complete turns is too much or too little?  

 

I'm cutting at 900-1100 SPM...the blade kept breaking when I was running it much faster than that.  Does the saw speed impact how tight of a turn I can make? 

 

Also attached is the first puzzle I cut.  The cuts are kind of random...wasn't following any lines or curves...just cut it as I felt like it at the moment.  Appreciate any feedback / critique on the work and how to improve.  Thanks!

Gordon

[Wichman]

There are a lot of questions here, so I’m going to try to take them one at a time.

Blade breaking. Hegners have some unique issues, including the size of the blade clamps.

 

From the Hegner manual:

e) Other Blade Clamp Sizes

Blade clamps delivered with machine are the medium, or 0.7 mm size. These clamps

are suitable for the vast majority of blades. Other clamps sizes are useful as follows:

0.5 mm clamps are used for small blades, when they are either not held tightly enough,

or if they show excessive breakage at the clamp exit point. If either of these problems

occur with blades in size 4 or smaller when using standard clamps, using the CLO.5

blade clamps is recommended and should reduce or eliminate the problem.

1 mm clamps are used strictly for blades that are too large to fit into standard clamps.

This may include bandsaw blade scrap, certain large metal-cutting blades, rod saws,

and emery boards, which can be used for finishing and shaping work on your HEGNER.

1 mm clamps should not be used on blades smaller than size 9.

 

Telling the clamps apart

The medium clamps have a divot on the side opposite the tuff screw head. The other two do not have any markings, but it’s fairly easy to see the difference between those two.

 

The puzzle blades are equivalent to a 2/0 blade, so you would be ahead to obtain a set of 0.5 mm clamps. When I started using the .5 clamps my breakage went down.

 

Additional information from the manual:

 

Blades break near ends

Check blade clamps for burr on inside clamping edge

Check blade clamps for straight up-and-down position

when blade is tensioned

Can clamps pivot freely?

Check blade clamps seats for horizontal alignment

Check for proper clamp size. Small blades should

not be mounted in large clamps

 

Blades break near middle

Check blade chart for proper selection

Check tension, increase if in doubt

Check sawing technique (perhaps excessive side pressure)

Check blades for factory defect, try other batch or size

 

 

Stroke length

You may want to try the saw on the short stroke length. When I converted my Hegner, it helped with blade breakage and control.

 

[barb.j.enders]

I don't know anything about the Hegner.  What size blade are you using?  There are some very small blades available.  FD do have one called Puzzle blades.  It has been a while since I cut jigsaw puzzles, but I do recall it easier to cut one direction over the other.

[Gordon Wu]

8 hours ago, Wichman said:

There are a lot of questions here, so I’m going to try to take them one at a time.

Blade breaking. Hegners have some unique issues, including the size of the blade clamps.

 

From the Hegner manual:

e) Other Blade Clamp Sizes

Blade clamps delivered with machine are the medium, or 0.7 mm size. These clamps

are suitable for the vast majority of blades. Other clamps sizes are useful as follows:

0.5 mm clamps are used for small blades, when they are either not held tightly enough,

or if they show excessive breakage at the clamp exit point. If either of these problems

occur with blades in size 4 or smaller when using standard clamps, using the CLO.5

blade clamps is recommended and should reduce or eliminate the problem.

1 mm clamps are used strictly for blades that are too large to fit into standard clamps.

This may include bandsaw blade scrap, certain large metal-cutting blades, rod saws,

and emery boards, which can be used for finishing and shaping work on your HEGNER.

1 mm clamps should not be used on blades smaller than size 9.

 

Telling the clamps apart

The medium clamps have a divot on the side opposite the tuff screw head. The other two do not have any markings, but it’s fairly easy to see the difference between those two.

 

The puzzle blades are equivalent to a 2/0 blade, so you would be ahead to obtain a set of 0.5 mm clamps. When I started using the .5 clamps my breakage went down.

 

Additional information from the manual:

 

Blades break near ends

Check blade clamps for burr on inside clamping edge

Check blade clamps for straight up-and-down position

when blade is tensioned

Can clamps pivot freely?

Check blade clamps seats for horizontal alignment

Check for proper clamp size. Small blades should

not be mounted in large clamps

 

Blades break near middle

Check blade chart for proper selection

Check tension, increase if in doubt

Check sawing technique (perhaps excessive side pressure)

Check blades for factory defect, try other batch or size

 

 

Stroke length

You may want to try the saw on the short stroke length. When I converted my Hegner, it helped with blade breakage and control.

 

Thank you.  I didn't know the clamp size made a difference...I also didn't know I was using the medium clamp...I'll switch it out for the small clamp.

 

A week ago (half way into my experimentation), i changed out the top clamp for the QuickClamp.  Any thought on the usage of the QuickClamp for the 2/0 blade size?  I haven't kept track of how many breaks I got but it's always breaking at the bottom since I started using the QuickClamp and the blades look like the picture below when I changed it out (when it's not breaking).  The teeth are to the left of side of the blade in this picture.  And the breaks are always the size of that bent piece...I have to push it out of the clamp with another blade.

 

 

54 minutes ago, barb.j.enders said:

I don't know anything about the Hegner.  What size blade are you using?  There are some very small blades available.  FD do have one called Puzzle blades.  It has been a while since I cut jigsaw puzzles, but I do recall it easier to cut one direction over the other.

I'm using the FD Superior Puzzle Blade.  I just don't know if the blade flexing so much is normal...I get kind of nervous whenever the blade flex so much...combined with a moving saw, it becomes a huge distraction while I'm cutting.  Then my cuts get wonky because I'm so nervous the blade will break.  Thoughts?

[Scrappile]

If you go to this site, and scroll down about half way there are some videos that may help you.

https://www.advmachinery.com/collections/hegner-scroll-saws

I kinda disagree with the one on tensioning.  I use more tension than the video shows.  When I test the tension on my Hegner by plucking the blade, I want to hear a high "C" note not a lower plucking sound.  Breaking blades happen and the more experience you gain the less you will break.  feeding th wood into the blade too fast, improper tensioning, wrong blade for the wood you are cutting can all cause blade breakage. When I first started with my Hegner I broke lots of them.  So many I called Advance Machinery for advice.  They gave me suggestions, and all of a sudden I just got comfortable with the feel of the Hegner. But, after 14 years of sawing I still break blades occasionally.  Just part of the craft. Now I would not part with mine. The only other saw I would want is another Hegner.

The curve you picture on the blade, is that the top or bottom of the blade?  If it is the top. when you put the blade in the top clamp insert it until it stops then pull it back a fraction of an inch, just a little, then clamp it.  The stop is the end of the blade hitting the bolt that goes through the clamp. Pull it back just enough so it does not touch that bolt.  Tightening the clamp with the end of the blade touching that bolt can cause a hockey stick bend like that. 

Do not get discouraged, it takes a little time to work the kinks out, no matter the saw you are using.  

[OCtoolguy]

I'm thinking you need to increase your tension too. You shouldn't be able to bow your blades that much.

[Scrappile]

Oh, I use the quick clamp with all blades.   Quote from Advance machinery:

Use the QuickClamp instead of a standard blade clamp at the upper end of your sawblade, and align your blade instantly! A positive stop helps you put your blade in the same position every time, and the easy-grip knurled aluminum knob places pressure directly on the blade for slip-free tightening. Unlike the standard HEGNER blade clamp, the QuickClamp is designed to be locked into place in the upper arm of your HEGNER saw at all times. And since it doesn't require a wrench, it's super-fast to release and re-tighten for speedy blade changes, especially for frequent inside cuts! The QuickClamp is supplied complete as shown, and accepts all blade sizes."

 

 

 

 

[Wichman]

1 hour ago, OCtoolguy said:

I'm thinking you need to increase your tension too. You shouldn't be able to bow your blades that much.

I'm reading between the lines here, but I think he is talking about the blade turning 45 degrees while trying to cut the small radius's; if you look at the blade head on, and without power to the saw, turn the workpiece 45 degrees to the left, the saw blade will turn to the left. He's not pushing sideways on the blade, he's turning the workpiece to get the circle.

[Wichman]

1 hour ago, OCtoolguy said:

I'm thinking you need to increase your tension too. You shouldn't be able to bow your blades that much.

     I'm reading between the lines here, but I think he is talking about the blade turning 45 degrees while trying to cut the small radius's; if you look at the blade head on, and without power to the saw, turn the workpiece 45 degrees to the left, the saw blade will turn to the left. He's not pushing sideways on the blade, he's turning the workpiece to get the circle.

     Two complete turn's is the maximum tension according to the manual. When I use numbers to express tension I use 1/4 turns, so 4/4 would be one complete turn and 8/8 would be two. The manual states 2/4 (1/2) rotation as a minimum tension. I generally use 6/4 for my work.

The hockey stick here is most likely caused by the wrong blade clamp, instead of putting pressure across the whole clamp face, there is instead a pinch point where the blade bends.

[Gordon Wu]

Thank you all for the encouragement.

 

9 hours ago, Scrappile said:

The curve you picture on the blade, is that the top or bottom of the blade? 

It's the bottom of the blade.

I will try 6/4 of a turn.  At first, I wasn't keeping track and wasn't re-tensioning it after every time I put on a new blade...then when I started doing that and realize there's some variation on how much tension there is when I install a new blade...is that because I'm not consistent in the length of blade that's getting clamped?  

I'm going to cut some more puzzles this weekend and see how it works out and report back!  Thank you all!

[Wichman]

22 minutes ago, Gordon Wu said:

Thank you all for the encouragement.

 

It's the bottom of the blade.

I will try 6/4 of a turn.  At first, I wasn't keeping track and wasn't re-tensioning it after every time I put on a new blade...then when I started doing that and realize there's some variation on how much tension there is when I install a new blade...is that because I'm not consistent in the length of blade that's getting clamped?  

 

I keep a Can-O-Air next to the scroll saw, when I change blades I use the air to blow out all the debris from the clamp. I place the blade clamp in the holder, the wrench on top and gently tilt the clamp back with the wrench until I take out all the slop. Next I put the blade in the clamp and tighten until resistance is felt, I then pull the blade out just enough that the clamp screw doesn't move the blade; now tighten. Be careful not to overtighten the blade, and make sure the blade is square to the clamp, it the blade is not square to the clamp it will put undue pressure on the blade and reduce the longevity of the blade.

To me, the puzzle blade looks and feels much like the Polar blades, the biggest difference is the Polar blades are skip tooth and the puzzle blades are not a skip tooth.

You should, with practice, be able to cut a zero radius turn. I use this technique often. One practice cut I use is this: Using a 3/4" to 1 1/4" thick piece of scrap, set the scroll saw to cut at an angle ( 30 degrees works ), cut straight in about an inch, then carefully rotate the scrap 360 degrees, you should get a cone shaped "waste" piece from the bottom of the scrap.  

[barb.j.enders]

22 hours ago, Gordon Wu said:

I'm using the FD Superior Puzzle Blade.  I just don't know if the blade flexing so much is normal...I get kind of nervous whenever the blade flex so much...combined with a moving saw, it becomes a huge distraction while I'm cutting.  Then my cuts get wonky because I'm so nervous the blade will break.  Thoughts?

Sorry,  I know nothing about the Hegner.  When I was cutting jigsaw puzzles, I was using my DeWalt.  I know the tension needed to be up there.  

[Wichman]

> Is there a general rule on the minimum radius for a cut vs the width of the blade or wood hardness/thickness?  Am I

> simply cutting my pieces smaller than I should?  

There are no real guidelines, there are too many variables i.e.   wood hardness, thickness of the piece, speed, etc.

Here are a few pictures to help you see what can be done. The wood is one piece of 1/2" Elm stacked with a 3/8" of Elm, for a total of 7/8" thick. I cut directly into a waste area and then slowly rotated the piece and came right back out the same kerf. In the first picture I used a #2/0 Polar blade, in the second I used a #1 polar blade. The saw speed was set at 1350 and I'm using the short stroke .

 

The next two pictures show how tight a turn you can make, no extra pilot holes, I just followed the lines. I used the #2/0 blades here, the rest will be cut with FD Polar #1.

  

[garryatpa]

There are quite a few questions in the above posts.  I hope some of the comments below will help.  I have a Hegner 22 that I bought in 1993 and I am still using it.   The only part that seems to wear and cause a knock is the link connector bar, which I have replaced about every 15 years.

I have never tightened my tension 2 turns.  When I change blades because of breakage or to a different size I adjust the tension - turn the tension knob until all play is taken up then tighten it another 1/2 to 3/4 turn.  There may be times that you have to re-tension the blade because the tension knob turns as the saw is running.  

Gordon re blade tip bent like hockey stick - caused by the blade not being centered in the bottom clamp. Place the blade into the bottom clamp until it hits the clamping screw, back the blade away from the screw just a hair and tighten the screw , in this way when you tighten the screw it does not touch the blade and cause it to move.   Make sure the blade is lined up with the pointed tip of the clamp, this is most important.

 

Making tight turns with any blade may be assisted by taking a fine sandpaper, attaching it to a flat strip of wood and , while the saw is running hold the sandpaper against the back corners of the blade at about a 45 degree angle to remove the sharp corners along the lower 1 to 2 inches of the blade.   This will allow the blade to corner more easily.  I have only used this method a few times and that was quite a while ago, but worth a try.  

When making tight turns always keep the saw running, I find that I am most comfortable at a speed of about 1300 on the dial of the Hegner.  Stand at the front of your saw centered facing the blade.  Do not push the wood to either side. Note: To check if you are pushing the wood to one side or the other , as you are sawing stop the saw while hold the wood still.  After the saw is stopped , lift your hands off the wood, and if the wood moves to either side of its own accord you need to adjust your sawing as you are not pushing straight back on the wood.   When turning the wood use one hand as the pivot point hand which does not move or moves very little and apply a little pressure down near and to the side of the blade, the other hand is used to turn the wood very slowly while slowly pushing the wood through the blade. Only stop after finishing the curved cut if you stop.  Do not move the wood when the saw is stopped.   

 

I believe I have seen tables for band saws which give the radius of a circle for different sizes of saw blades.  I think the same would apply to the scroll saw in that a 2/0 blade would be able to saw a tighter radius than a number 5, or 9, although a number 2/0 and a number 5 will both be able to turn "on the spot". (higher blade speeds would help "on the spot turning"  .  

When you are turning and the blade is at a 45 degree angle I am thinking you are forcing the blade to turn faster than it is able to saw. The only time my saw blade is at 45 degrees or teeth not facing the front is if I stop the saw and turn the wood.  Increasing your saw blade speed may help.   

Breaking blades - In MHO over tensioning  and under tensioning both cause blade breakage.  Under tensioning I believe is worse than too much.  When sawing puzzles , which I have sawn only a few, you must turn the wood first one way and then reverse and turn the other way in order to saw the tabs and openings for the tabs.  I find that if I am sawing small ornaments and saw one direction then turn to the opposite direction that it is much like taking a piece of wire and bending it back and forth in order to break the wire.  The more sharp turns one way and then the other the more often blades will break because the bending weakens them.  What do other puzzle makers feel about this theory?  Maybe slowing the speed at which you push the wood through the blade will help reduce blade breakage, but keep the saw speed up at the same time.

 

Garry .  

 

[Gordon Wu]

Okay it's been a couple of week since I've had significant amount of time with the saw.  I've played with different tension settings on the Hegner saw.  Below is a picture of the bottom blade holder:

 

 

The picture isn't completely leveled but you can see the blade holder is tilted one direction.  I realize that happens more when I have more than 1 turn of tension.  The strange thing is it's not always tilting.  And whenever I see it's tilting, I try to push it back to being straight but after cutting for a little bit, I'd check and the holder is tilted again.  When I see that, the blade ALWAYS looks like a hockey stick at the end.

 

Regarding on-the-spot turning, I don't know why I can't do that.  And it is always when I'm trying to rotate the wood counter clockwise.  I have no problem turning clockwise.  It doesn't help that it varies from blade to blade even within the same pack.  These are the Flying Dutchman Superior Puzzle Blades.  I've gotten to the point where I would mount a blade and cut a radius on a piece of scrap wood...and if it doesn't cut well, I just put the blade in the scrap pile and try a new one.  I'm averaging one blade out of every 4-6 blades that I'm setting aside.  I'm not saying the blades are bad, just not sure if I'm not mounting them right or the tension is wrong or something else I'm doing wrong.  And this is all using 1/4" baltic birch plywood.

 

I read that it may be part of how a blade is made...there's burrs on one side?  I can definitely feel more tug when I run my fingers on the right side of the blade compared to the left.  I guess that may explain why it cuts better when I'm turning clockwise vs counter clockwise.  I'll get some fine sand paper and try sanding down a few pieces to see how that goes.

 

Also, I've been running my saw at a speed of 700-900.  There was once when I had the saw faster than 1400 and the blade broke and all the rattling spooked me so I haven't tried going so fast again.  But I'll try again  and report back!

 

As a side note, I got some 1/8" basswood plywood just to play around.  It cuts like a hot knife through butter.  I can also get a tighter turn...not sure if it's due to the thinner wood or softer wood.  But it doesn't feel as substantial...sturdy as the 1/4" baltic birch.  

[Scrappile]

Gordon, I do not think that matters; the clamps on a Hegner do not sit solid in the holder, they "Float".  Even the top clamp should not be tight in the holder unless you are using the Quickclamp;  it is suppose to be tight in the clamp holder.  If you watch the video on the Advance Machinery site, it shows you snapping the lower clamp in. There is nothing to hold it in place tightly. The top clamp goes in, the knob is screwed down to it, and then backed off a little so the clamp is not held tightly.  Again the exception to this it the Quickclamp, it is held tight in the clamp holder.

It also appears that the blade is in the clamp not quite perpendicular to the clamp.  If it is perpendicular the clamp should sit straighter in the clamp.  

[JTTHECLOCKMAN]

10 hours ago, Gordon Wu said:

Okay it's been a couple of week since I've had significant amount of time with the saw.  I've played with different tension settings on the Hegner saw.  Below is a picture of the bottom blade holder:

 

 

The picture isn't completely leveled but you can see the blade holder is tilted one direction.  I realize that happens more when I have more than 1 turn of tension.  The strange thing is it's not always tilting.  And whenever I see it's tilting, I try to push it back to being straight but after cutting for a little bit, I'd check and the holder is tilted again.  When I see that, the blade ALWAYS looks like a hockey stick at the end.

 

Regarding on-the-spot turning, I don't know why I can't do that.  And it is always when I'm trying to rotate the wood counter clockwise.  I have no problem turning clockwise.  It doesn't help that it varies from blade to blade even within the same pack.  These are the Flying Dutchman Superior Puzzle Blades.  I've gotten to the point where I would mount a blade and cut a radius on a piece of scrap wood...and if it doesn't cut well, I just put the blade in the scrap pile and try a new one.  I'm averaging one blade out of every 4-6 blades that I'm setting aside.  I'm not saying the blades are bad, just not sure if I'm not mounting them right or the tension is wrong or something else I'm doing wrong.  And this is all using 1/4" baltic birch plywood.

 

I read that it may be part of how a blade is made...there's burrs on one side?  I can definitely feel more tug when I run my fingers on the right side of the blade compared to the left.  I guess that may explain why it cuts better when I'm turning clockwise vs counter clockwise.  I'll get some fine sand paper and try sanding down a few pieces to see how that goes.

 

Also, I've been running my saw at a speed of 700-900.  There was once when I had the saw faster than 1400 and the blade broke and all the rattling spooked me so I haven't tried going so fast again.  But I'll try again  and report back!

 

As a side note, I got some 1/8" basswood plywood just to play around.  It cuts like a hot knife through butter.  I can also get a tighter turn...not sure if it's due to the thinner wood or softer wood.  But it doesn't feel as substantial...sturdy as the 1/4" baltic birch.  

I use FD Supior puzzle blades and love them. They are a milled blade and not a stamped blade. This means they should cut the same both directions because the teeth are not all pointing in one direction. On stamped blades it is indeed possible to make tighter turns in the direction the teeth face because they are cutting faster. Many people get around this by sanding the edges off the back of the blade to help making turns smoother. This gets toiugh to do with thin blades such as puzzle blades which really do not need it but you could try to see if it helps you. Puzzle blades are thin and require a lighter touch when using because they break easily. Using a speed that is as fast as you can handle because of vibration or control helps. You have to let the blade do the cutting and not force the wood. This is fact with all woods and all projects. Yes bass wood is easier to cut with. BB plywood has many layers and has glue so this wears blades faster but is a more stable wood. 1/4" is harder than 1/8" wood in any species. That is just fact because you are cutting more material. If you are having better control and luck cutting one way than stick with that. No need to keep switching directions. 

As far as Hegner. i had one and had no problems. Need to make sure your clamp is not cracked. They had problems with those clamps. Because you tighten down on such a small piece of metal it can stress the metal of the clamp which acts like a clamp. Thus the different size clamps. One size does not fit all blades properly. That is important. Setting the blade in straight and to the back of the clamp is important but straightness is not critical but shoot for it. Those clamps are made to pivot in the holders because of the triangle end shape. They rock back and forth at times when cutting to help keep the blade from breaking. They seek their own straightness when tensioned properly. I will have to say and this is just my opinion, they are not the best clamp if you do alot of fret work because of the way they work. I did not like them. 

Scrolling is all about touch. It takes much more practice to learn to scroll in both directions than it does to learn one. I say this because your dominate eye moves. You may not think it but it does. This means your hands follow and the pressure you apply has to match. You usually break more blades in one direction than other because of this. Again just my opinion. Some people master it easily and the larger the blade the easier it is. 

Here are some examples of my use of the FD puzzle blades. I will say it took me a few tries to get the feel of the cuts but after that it goes smooth. I use an RBI 20" saw.

here is Steve Goods version of explanation of blades.

https://www.stevedgood.com/scrollsawblades.pdf

Edited November 2, 2025 by JTTHECLOCKMAN

[Scrappile]

I have been working on a detailed picture, and got to thinking about your comments about your bottom clamp.  I never paid much attention to mine.  So decided I would look.  This is what it looked like.  Been working fine.  

 

[JTTHECLOCKMAN]

53 minutes ago, Scrappile said:

I have been working on a detailed picture, and got to thinking about your comments about your bottom clamp.  I never paid much attention to mine.  So decided I would look.  This is what it looked like.  Been working fine.  

 

Because you are use to it. I will say you did not center the blade in the clamp when you installed it. It maybe fine but bet you are maxed out how far straight up and down the blade is. When that happens you now have added more back to front motion instead of straight up and down motion. This can cause overcut when cutting pieces out especially small delicate pieces. If your top holder is locked down this increases even more. If the top holder is allowed to pivot as much as the bottom you will be OK. I still suggest shoot for straight blade insertion in clamps at all times. Again I did not like those clamps much on that saw. yes it is a great saw but now they have options to change those clamps an I would have. 

[Gordon Wu]

Alright, here to report back on my experiment with sanding the FD superior puzzle blade.  I tried it out a little bit...keeping the sand paper on the side while running the saw, or gently pressing on the blade at a 45 degree angle from the side.  The results are the blade just stopped cutting through the 1/4" baltic birch.  I would have thought the sanding would sharpen the blade but it somehow dulled the blade.  But it was a fun experiment on a Sunday afternoon

[JTTHECLOCKMAN]

Why are you sanding the blade? That will always dull a blade. If you are sanding the backside corner edges to make them smoother for turning purposes then use a sanding board. Some people use a fingernail file sander or these. They come in all type styles but it is a stick with sandpaper on it. https://www.ptreeusa.com/abrasive_detail_sanding.html

 

If you touch the teeth in any way with sandpaper you dull the blade. 

[Gordon Wu]

Hmm...my bad...I mis-read the message about sanding the backside corner.  I'll try that when I have time.

 

I ran a quick experiment to see how tight of a radius I can cut with various tension on the Hegner saw.  See below for the results:

 

 

I started at 3/4 of a turn of tension...made a cut by turning clockwise by 90 degrees then counterclockwise by 90 degrees.

Then I made cuts with higher and higher tension.  For the cuts, I tried to minimize the twist I see in the blade.  I almost never see twists in the blade when I'm turning the wood clockwise, and as you can see in the pictures, the cuts were tighter as I racketed up the tension.  But the counterclockwise turns remained about the same in terms of the radius.

 

Is that from bad technique?  This is using a new FD superior puzzle blade.  I tried to minimize the cuts so that the blade isn't worn down from one tension setting to the next and I used the same blade for all the cuts.  

 

I'll try to sand the backside corner and repeat the test again.  But appreciate any feedback.  Thank you!