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Forum topic by leftcoaster posted 05-23-2016 02:19 PM 396 views 0 times favorited 9 replies Add to Favorites Watch
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leftcoaster

82 posts in 337 days


05-23-2016 02:19 PM

I’m making a piece of furniture (small table) with a 3/4” top. It’s for personal use, so no big deal that it isn’t exactly 3/4” in the end—I had to plane off another 1/16th” inch and am OK with that.

For next time, my question: I purchased 4/4 stock and inspected it as best I could during board selection process. After planing to 3/4” there were some small defects. I”m not sure what these are called but there was a slight depression in the surface. Not a groove but sort of like a crater on the moon seen from very far off—maybe 1/8” at the widest part and about that much square.

How do you guys avoid these? Do you buy 5/4 and plane or resaw off more wood to get to a completely smooth surface? Use wood filler? Buy more board feet so you can be choosier? By the time I saw these I was already sanding the glued up panel, so more board feet wouldn’t have helped in this instance.

Grateful for your feedback….


9 replies so far

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MadMark

977 posts in 914 days


#1 posted 05-23-2016 02:26 PM

Cupping (flip side is crowning) generally shows after planing if the stock isn’t fully dried. Not much you can do except buy kiln dried (KD) lumber. Do not lay milled lumber flat or on concrete.

M

-- Madmark - Madmark2150@yahoo.com Wiretreefarm.com

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leftcoaster

82 posts in 337 days


#2 posted 05-23-2016 02:29 PM

No cupping/crowning. Board is completely flat and square. There’s just a little surface depression. Lumber comes from Macbeath, which is a reputable source for KD lumber.

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dbray45

3178 posts in 2237 days


#3 posted 05-23-2016 02:53 PM

If I understand what you are describing, these are little pieces that the planer is exposing as you run it through and not at the end of the boards where the planer takes off too much.

This is caused by the direction(s) of the grain, hidden knots, all kinds of things. Sometimes it is the wood species that is the cause. Try turning the board around and running it from the other direction.

Curly maple and ash can do this a lot.

What I do – get the wood flat, and in planing, take off as little as your planer will take until you get a clean surface. Once you have the one clean side, turn the board over and finish making it the right thickness. If that doesn’t work, get a drum sander.

-- David in Damascus, MD

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leftcoaster

82 posts in 337 days


#4 posted 05-23-2016 03:03 PM

Thank you David. This is eastern hard maple and my first time working with it. And while I know that grain orientation matters when planing, I failed to apply that knowledge this time. I think I should put a label on the planer to remind myself. And yes, I don’t remove more than 1/32” at a pass.

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dbray45

3178 posts in 2237 days


#5 posted 05-23-2016 03:06 PM

I usually go about 1/64 on the good side – takes longer but it is worth it

-- David in Damascus, MD

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leftcoaster

82 posts in 337 days


#6 posted 05-23-2016 03:10 PM

Good tip—I am in no rush.

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pintodeluxe

4853 posts in 2274 days


#7 posted 05-23-2016 04:49 PM

I start with 5/4 for a 1” top, or 4/4 for a 3/4” top. I glue up pairs of boards, and run them through the planer once the glue has cured. Then I glue these planks together to make the top. That way I only have one or two glue lines to sand. Works pretty good.

Tearout is a major problem with straight knife planers. The only way I was able to solve that issue was with a helical head.

Good luck with your project.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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leftcoaster

82 posts in 337 days


#8 posted 05-23-2016 05:03 PM

Never occurred to me to defer the planing step until one pair of boards was glued up. Great idea!

View JBrow's profile

JBrow

817 posts in 381 days


#9 posted 05-24-2016 12:30 AM

leftcoaster,

In my experience, a depression in 4/4 rough lumber generally becomes apparent when face jointing or planing the lumber. I have seen the depression similar to the one you described result during the flushing up and/or smoothing processes. For example tipping a random orbital sander even slightly can remove a surprising amount of material in short order. Excessive use of a cabinet scraping in one spot can produce a similar divot. I like to mark the entire surface of the panel with a pencil before scraping or sanding the glue-up. The pencil marks reveal the high and low spots during sanding, allowing judgments to be made as to where and how much material to remove or leave an area of material unworked.

Removing the crater defect in a flushed-up, glued-up panel, whatever the cause, is possible without reducing the thickness of the entire panel. The method involves removing progressively less material outward from the defect in all directions. This, in effect, extends the crater outward in all directions, but feathered gradually to eventually meet the surface of the top. On close inspection under oblique light, the divot could be seen, but by feathering it far enough out from the center, it would be unnoticed when the top is placed into service. Obviously, removing a crater more than perhaps up to a 1/16” deep with this feathering technique may not be possible.

During the finish sanding process, I sometimes find little previously unnoticed defects in the wood. Sometimes these are surface checks or perhaps a small knot with some cracking, or maybe a worm hole. In these instances I often use shop-mixed wood filler to erase the defect. I have done this a couple different ways. In one method, I apply PVA wood glue to the defect and press it into the defect as deeply as possible. Then dust from the same wood, taken from the sander’s dust bin, is sprinkled over the wet glue and pressed deep into the defect. After the glue has dried, I sand away the dried glue and excess wood dust. Usually a second or even a third application is required to achieve a repaired defect flush with the surface. The second method is similar, but I mix wood dust with glue to form a paste. After glue is pressed into the defect, the wood paste is pressed into the defect. Both methods yield similar results, where the repair is visible as a little darker than the surrounding surface but the repaired surface is flush. I suspect using colorless glue rather than yellow PVA glue could improve the appearance. Also generating wood dust using a cabinet scraper would result in dust free of sand paper aggregate which can also affect the color of the repair. I have not experimented with alternative glues or collected dust, so I am not sure whether a better color match is possible. I doubt the repair would ever blend perfectly with the surrounding wood. In any event, I prefer these defect repair methods over commercially available wood fillers.

When gathering lumber together for a project, I like to have 15% to 20% more lumber than is required to complete the project if working with FAS, F1F, or Select graded lumber. A larger allowance for 1C and lower grades is my preference. These allowances make getting good grain and color matches more likely and compensates for mistakes and latent defects.

It is my understanding that mills consider 4/4 stock thick enough to dress down to ¾”, but I do not believe that considers panel glue-ups. In my experience, achieving a ¾” thick glued-up panel from 4/4 stock is difficult, but glued-up panels close to ¾” thick can be reliably achieved. I resign myself to a little extra work and time using 4/4 stock and then work with the thickest panel I can achieve, usually at or greater than 11/16” finished thickness. Arriving at a final glued-up panel at ¾” would be straightforward with 5/4 lumber, but I personally hate the thought of the extra time, cost, and loss of ½” of material.

Face jointing one face of the lumber and then planing to a thickness greater than ¾” allows boards to be selected for glue-up while preserving a little material for the removal after glue-up. Grain and color match and defects become apparent with this minimal milling. Boards selected for glue-up can then be glued together and then worked down to the ¾” thickness. Arriving at ¾” thickness is more likely if the glued-up panel comes off the clamps with glued seams flush. Perfectly flush glue seams are difficult to achieve. Flat stock of the same thickness with well mating glue surfaces, careful planning and the use of cauls can consistently produce mostly flush glue seams.

Not a method for the faint of heart and a method I just recently attempted with good results is to joint just one face flat, square the edges to the jointed face, and proceed to glue-up. Before glue-up, the jointed faces are inspected for defects and color and grain match. The jointed face would become the “show” face, at least tentatively. This leaves one face rough but with plenty of material that can be removed to flush-up and smooth the panel. However, this is a risky method and probably only practical if a drum sander or planer wide enough to accommodate the width of the glue-up is available. Also, if the glue seams on the jointed face do not line up well, arriving at a flat panel with parallel faces can become a challenge and defeats the purpose of this unconventional method. Keeping glue seams aligned when the adjoining boards are not the same thickness is not easy to do.

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