Uneven blanks

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Andyww

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Jan 9, 2017
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When I turn a blank, I get it down to a reasonable width with tools, then I go the rest of the way to the bushings with sandpaper. I've never had an issue, however, I was working with some spalted oak in a slimline style and I noticed that one side of the blanks was flat and even with the bushings while the other sides were still thick. I kept trying to sand them even and round but it just got worse. Eventually the flat side was even becoming indented while the other sides were still thick. I thought maybe my mandrel was bent but I fixed the problem slightly by getting my tools out and lightly running them down the blanks. It evened them out. Any ideas? Was the grain on that side of the blanks softer maybe and more likely to quickly sand down compared to the other sides?
 
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1080Wayne

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Common problem with spalted woods and sometimes with cross-cut pieces . Wood density and hardness can vary a lot within a blank . One of the reasons why some prefer stabilized blanks . Application of thin CA before sanding usually helps , but give it several hours to cure .
 
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Skie_M

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Bushings may be out of round .... it may not even be the outer diameter you need to worry about, but the inner that has been worn and damaged by rubbing against the mandrel.

See if replacing the mandrel and/or bushings solves your out-of-round problem.


Another possible fix is to switch over to working without a mandrel, and turning between centers.
 

Cwalker935

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My guess is that the wood is softer in the areas where you are getting flat spots and more material is being removed quicker from those areas when sanding. Use a good sharp skew and try to minimize the amount of sanding that you have to do. Soak with thin ca before you start sanding as well.
 

leehljp

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That is a common issue with certain woods and trying to sand it down. It means too much pressure is being applied. If you want to use sand paper to bring it down, and I have done this plenty of times, it needs to be done with gentile pressure and occasional use of skew or scraper. Scrapers do better on hard woods and skews do better on softer wood. In this case Oak has softer tissue and hard at the same time. As said above, soak it in CA. Turn down a little and sand. After sanding, put the skew/scraper to it gently to keep it round.

BTW, you can cause similar issues by using too much pressure with a not-perfectly sharp instrument. "Sharp Tools" is relative and as such cases problems in discussions and practice. What one says is "sharp" would not dare be used by another. A "somewhat sharp" tool will cut but takes more pressure to cut down. This pressure with the tool forces the pen into a contorted position as little as .003 or .005 and will result in similar cuts as sanding too hard.

Sharp: gently touch the blank and see if it is cutting; sharp will, "not sharp enough" will require just a tad bit of pressure. Sharp tools should not need pressure on the blank to cut. The spinning blank will be cut as soon as it touches the sharp tool. A KEY part of turning pens is learning the steps outside of "making a pen": Sharp tools (and knowing how to correctly sharpen and keep sharp during the complete turning) , calipers, techniques, practice, "feel", and others too.

There is a chance that the bushing wholes were drilled off center. If you have calipers, check them. If you don't have calipers, you need them.
 
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jttheclockman

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I think you and others hit on what the problem is with the density of the wood in one area as opposed to the other. This happens alot in various woods when sanding endgrain too. If you need to sand I suggest you use a backer piece of wood on your sandpaper. this will span the entire blank and not just concentrated areas which you get with finger pressure. I love to use my skew to get me home and skip the sandpaper. This eliminates the sanding lengthwise need too. Good luck.
 

Andyww

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Thanks everyone for the advice. I was thinking this stuff might be trouble. It's almost weightless and it just wants to splinter every chance it gets.
 

Paul in OKC

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Yep, wood density difference. I have done several spalted wood pens from found wood. I usually turn to about 1/16" proud of the bushings and then start soaking with CA. Turn close and CA before starting to sand. Makes it easier to turn with your tools as well.
 

Skie_M

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Thanks everyone for the advice. I was thinking this stuff might be trouble. It's almost weightless and it just wants to splinter every chance it gets.
Aha ... yeah, when it's THAT spalted, you're looking for trouble if you don't stabilize it.

Use your tools to get down close and at least stabilize the exterior with several layers of CA before you start your sanding. You'll want to stabilize this stuff FIRST because the sanding dust will get stuck in the wood pores and you'll have a heck of a time cleaning it afterwards.

Once you've reached your finished dimensions, a few coats of CA to protect the less dense wood from fingernails, skin oils, and the elements would be in good order.
 

sbwertz

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I don't have a pressure pot, but I've had good luck soaking such pieces in MinWax wood hardener. I've even put it in a jar and used my foodsaver to put as much vacuum on it as I could. It worked pretty well on very punky wood. (I have an old foodsaver I only use in the shop!)
 
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