How to determine runout in spruce top billets

[charangohabsburg]

With looking at the fur on the surface one rather judges the state of the sawblade and whether the log was frozen or not when resawing. Keep in mind that with a poorly sharpened plane blade one can cause tear-out even on a spruce top without runout! (The same goes for saw teeth).

Looking at the joining face of a top may help if it is not jet planed. But even so, this is sometimes very difficult or impossible.

Split it!

Whenever I want to learn about the runout of a top (of course only if it's in my possession), using a not too sharp knife I pry a two or three grain lines wide and 10 cm long splinter off one of those edges which anyway will be cut-offs:

Step 1

2011_D70_3571.JPG (58.15 KiB) Viewed 33223 times

Then I split this splinter in the other direction. No doubt, this top (a low grade one, btw) has a measurable runout of 1:28

Step 2
Runout ratio is 1:28 (low grade top. 1:15 would still be acceptable for low grade)

2011_D70_3573.JPG (47.51 KiB) Viewed 33223 times

I have measured runout ratios as bad as 1:15. And I have seen a top that failed because of really poor wood quality (the responsible luthier is not to blame but I bow with respect that people like he can make good sounding instruments out of the material they can get their hands on). That failed top had an estimated runout ratio of about 1:5. 1:1 would be 45%

This one is a master grade top without measurable runout:

Virtually no runout (Master grade).

2011_D70_3574.JPG (47.03 KiB) Viewed 33223 times

Same master grade top with closed gap in order to see better the "no-runout".

Virtually no runout (same Master grade top).

2011_D70_3575.JPG (46.99 KiB) Viewed 33223 times

[Kim]

Excellent post Markus, thank you.

I have put this image up before but I think it will fit well with this thread. It shows a number of bookmatched Sitka samples with varying degrees of runout as they appear under a finish.

There once was a high resolution image available of the above but the original link is now dead But if you click on the one I have uploaded it will display larger and is good enough to get some idea as they are marked one above the other, to the next in 1/4" gradients. This is to say the sample in the image marked 3/4" in 20, is telling us that the grain in that particular sample rises 'through' the board, from the bottom surface to the top surface, at an ratio of 3/4" for every 20" of the boards length.

This series of line drawings are quite good also for anyone not quite sure exactly what people are talking about when they refer to runout....some people confuse the term with straightness of grain on the 'surface' of the board from one end to the other. This image shows that it is actually referring to straightness of grain through the board. The top line drawing is meant to show a rough sawn edge, the next 2 are meant to demonstrate how it is more easy to observe runout in the edge once you shoot a 45 degree with a sharp plane:

(EDIT: Please note. Markus demonstrates further along in this thread why shooting a 45 degree along the edge of a board 'does not' make runout any easier to detect. The bottom two line drawings do successfully demonstrate exactly what runout is though so I will leave them displayed in this post.)

aaa_runout.gif (77.9 KiB) Viewed 33208 times

Cheers

Kim

[charangohabsburg]

What a great sample collection, Kim!
Are these tops still in this state? Maybe it would be great to attach runout ratio numbers to some of those samples.

[charangohabsburg]

Maybe it would be great to attach runout ratio numbers to some of those samples.

Oh, now I see... It seems that these ratios are already written onto the tops as 1/2 in 20, or 2 in 20 and so on. How did you measure them?

[Kim]

Not my samples Markus, just something I downloaded from a web site that is no more...I am sure that the owner would be happy that his hard work and great information still lives on at the ANZLF.

Cheers

Kim

[charangohabsburg]

Still glad you salvaged the picture.

[kiwigeo]

Excellent posts thanks Markus and Kim..

[Daniel_M]

Awesome, thanks gents.

[charangohabsburg]

[...] the next 2 are meant to demonstrate how it is more easily observed runout in the edge once you shoot a 45 degree with a sharp plane:

I disagree.

What you will see is just plain grain lines cut at an angle (no "quartered surface" anymore). If you don't plane your bevel exactly parallel to the grain lines these will appear at a raising angle, which is not the runout. Look here:

Not runout. Just grain lines cut at an angle.

2011_D70_3579.JPG (60.5 KiB) Viewed 33131 times

Now you might say "but look, there are some very fine silver lines!". These here:

That's no runout either.

2011_D70_3580.JPG (61.25 KiB) Viewed 33131 times

But now let's pry apart a bit of the wood to reveal runout more clearly...

That's the runout!

2011_D70_3581.JPG (54.02 KiB) Viewed 33131 times

Yes, runout is in the opposite direction than the lines in the two former pictures suggested!

A broken (split) surface normally will reveal runout, although sometimes not so clearly as here or as when continuing with my "step 2" - photo in my earlier post. A planed surface instead hides the runout unless you compare it's refraction with a bookmatched piece as it happens in a completed top.

[woodrat]

Nice Topic Markus....great work...very interesting.

John

[Kim]

Bugga!

Now I have to go out and regrade some of my smaller tops

Fortunately the vast majority are large tops with plenty of room to edge split regardless of how you lay that pattern and in those situations, as mentioned in the Wayne's Kootenay Tonewood thread, that is what I do when trying to determine runout. But I do have a few that I will need to look at again. These particular tops, most of which came from a vendor of Lutz who is 'not' Shane Neifer, are those which 'just' squeeze in the largest template I can fit but, because of incursions one way or the other, have good and bad points with each lay of the template. These leave me procrastinating so I had used the plane method on what was the most likely candidate for the outer edge of the upper bout and assumed under power of suggestion that what I was seeing was indeed runout. As you have demonstrated Markus, that clearly is not the case. So for me there are only a handful of tops in question and because I have my stash cataloged on spreadsheet, the culprits can be pinpointed and retrieved without too much trouble.

Thank you for clearing this up Markus and preventing me from propagated that same power of suggestion that had fooled me and then allowing it to affect others. Its a great thing when these forums work and I am sure I am not the only one to have learned a lesson here, not least of which is a reminder of the benefit of thinking things through for ourselves instead of lazily assuming something to be true just because someone took the time to do a liine drawing..at least that image remains affective at demonstrating exactly what runout is...there really is much confusion out there in that regard.

One thing I will add before I scuttle off with my tail between my legs, is that even edge splitting should only really be considered a good indicator of runout in a top. This is because sometimes, the degree of runout can change across the width of a board. Or it can appear in localised areas of the board that are away from the edge you have tested. As I see it though, splitting is by far the best option we have because every other method I know off is even less conclusive.

Cheers

Kim

[charangohabsburg]

[...] the degree of runout can change across the width of a board [...]

Absolutely true! Changes in runout across the width of the board are most often due to the twist in the tree. In these cases it is impossible to cut a board 100% free of runout. Spruce trees with no twist at all are quite seldom and I'd say that it's a sin to cut instrument tops with runout from a tree without twist. Easier said than done right, though.

Another reason for changes in runout across the width and also along the length of the board can be due to branches which were close to the position in the tree where the board was cut from. This kind of irregular runout is mostly (or always?) accompanied by not-straight grain. On the other side, not-straight grain by itself doesn't necessarily mean disturbing runout.

Last but not least there can be those changes of runout direction along the length of the board which are the effects of irregular growth such as change of twist direction and similar weird things - I imagine that most of us have seen pictures of flamed redwood tops. Talking of European spruce, at least what I have seen, "flaming effect" looks just lame, disturbing or ugly (I wouldn't even call it figure) and is the least thing I would want to build with.

[Mike Thomas]

I was just having a look at Rudolf Fuchs website ( http://www.germanspruce.com ) where he says that " a nice cross silk pattern reveals that the wood has been accurately split (no run out) and quarter sawn. Is pronounced silking generally regarded as a reliable indicator of little or no runout?

[Bob Connor]

I always assumed it was an indicator of well quartered wood Mike. That's the first time I've heard of it being associated with minimal runout.

Regards

[Mike Thomas]

Same here Bob. It would be interesting to know if what he says is true. He certainly has a good reputation as a tonewood supplier, so I imagine there is some foundation for his statement. I can't remember having seen a guitar with both pronounced silk and the harlequin look; if there's only one it would argue against what he's saying.

[Craig]

I was thrilled with this soundboard when it revealed so much silking. Not surprisingly ,it's a master set of Sitka . Now that it has finish on ,it displays no colour change between the bookmatched halves indicating little to no runout so maybe Mr. Fuch is correct.

THREE341.jpg (48.86 KiB) Viewed 32879 times

[kiwigeo]

Wheres the binding????

[Craig]

Wheres the binding????

Before finish ( shellac):

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[Kim]

When did you take up using the plastic moulding process to construct your guitars Craig???




















Incredibly sharp work mate.

Cheers

Kim

[kiwigeo]

Thank god there's binding. Guitars without binding just dont work for me.

[charangohabsburg]

I was thrilled with this soundboard when it revealed so much silking. Not surprisingly ,it's a master set of Sitka . Now that it has finish on ,it displays no colour change between the bookmatched halves indicating little to no runout so maybe Mr. Fuch is correct.

This is piece of decent, nearly quartersawn package grade Swiss alpine spruce:


As you can see it has nice silking:


... and quite a horrible runout (measured runout ratio of 1:11):


Today I cut this piece in two and joined it in "false bookmatch manner".

It is no surprise that the colour change is noticable without varnishing the sample, and even so without cleaning up the smeared fish glue near the joint.

In the sun:


In the shade:


And yet, in spite of apparently being wrong, Mr. Fuchs's theory is not totally wrong, only that he forgot to attach some numbers to it. Silk appearance starts to decrease when runout is far beyond what we would accept as suitable tonewood. If someone is interested in these numbers I can make an effort to explain it. I would have to do some drawings though.

Btw, in the German version of the Fuchs website there is no relationship between silk and runout mentioned.

[charangohabsburg]

Here some better pictures of the colour change.

After planing the surface of the jointed pieces ( = cleaned from glue rests) :


This is how silky 1:11 runout looks like "under varnish" (I'd better say "after slapping some shellac on" ) :

[Mike Thomas]

Thanks Markus for doing this. Since, as you have demonstrated, silking and runout can cohabit the same piece of wood, we clearly cannot take the presence of silking to indicate the absence of runout. I wonder if Rudy Fuchs is aware of what the English version of his website is saying?
This is a very useful thread, and I for one would like to see it as complete and as definitive as possible. If you can find time to do it, it would be nice if you could do the numbers, drawings, and explanation that you referred to above.

[Kim]

I agree completely with Mike Markus.

It would be really valuable input to the forum if you could find time to compile all of your excellent information, and any more you can add, into a definitive guide to be placed in the tutorials section.

This really has been a soft point in understanding for many builders here in AU and NZ. Many of us come to this craft from a wood working background, but most of what we learn along the way has come from local hardwoods and construction radiata. So it is fair to say that few of us have ever really had to contemplate runout before so when it finally does become a consideration, it is just too easy to follow the advice of those whom have lived and worked with spruces all their lives and are experience stringed instrument builds without too much thought.

In all honesty, what you have presented so far is the most detailed explanation for detecting runout in spruce that I have ever seen and I have no doubt it has cleared away much of the myth for many.

Thank you mate

Cheers

Kim

[charangohabsburg]

Just a brief side remark regarding runout: click!
It seams that one has not to hide himself when building with that kind of runout. Just charge a nice sum and set the customer on a 5-year waiting list to avoid he could complain!

If you can find time to do it, it would be nice if you could do the numbers, drawings, and explanation that you referred to above.

OK, I will search (and find) that time.
It just wouldn't make much sense to do it if nobody would be interested.

This really has been a soft point in understanding for many builders here in AU and NZ.

Not only in AU and NZ Kim. If someone never has logged, split and resawn softwoods (like most luthiers anywhere in the world) it's harder to understand what runout is and how it shows (or doesn't show).

In all honesty, what you have presented so far is the most detailed explanation for detecting runout in spruce that I have ever seen and I have no doubt it has cleared away much of the myth for many.

Thank you mate.
I hope that I will nail down also that silk thing in a decent manner. Just give me some more days.

Cheers,