drying thin wood for coaster stock.

[doc henderson]

I have been doing laser engraving for gifts for a few years.  I can do groups of similar things like coasters.  I want the wood thin so the laser can cut out the coaster.  it can round the corners and leaves a flat black charred look to the edges.  I like 1/8th inch.  It can do 1/4 inch, but it is slower (takes longer) and if there is a knot or figure (pretty to look at) it may not shear all the way through.  the goal is stock that I can pull out and use, that is thin and stays flat.  I hate to have to plane a 4/4 board to small thickness, and hard to plane a thin board in maple as it can chip out.  I tried it in my heater with thin stir stick, and it warped bad, and did not dry well with heat, but little air movement.  so here it is in 1/4-inch rough stock, and 1/4 x 1/2-inch stickers every 8 inches.  



 

here is the maple that we split last week.  this is a thin could pieces to try.  18 inches wide, 9 feet long, 1/4 inch thick.



 

hand for scale.  



 

came from a tree alive 1 month ago, a bit ugly but will have some character on a 4 x 4 inch scale for wedding coasters.



  
my engraver table will hold and 18 x 24-inch piece. so that is why they are 18 inches wide.  and cut to 24 inches long.  



 
here is the stack with tiny sticker and every 7 inches or so.  

 

here it is with top boards and clamps.



 
using the same length clamps on the corners allows it to sit up off the table.  



 

starting out above 32% MC, the max for my meter.



 

here is the 19 buck WM fan, and the velocity feels strong coming out of the stack.  it smells of maple sap.  now to test it.  it felt stronger out of the stack as it was going straight, I think.  



 

here is the piece of yarn being blown at a 43° angle so about 320 M/sec.  +/- 310 M/sec.    8)  



 

yarn control group at 0 M/sec.  

[doc henderson]

If these can dry flat and plane out a bit, I can do groups of 24 coaster at a time.  after set up, it will engrave about and hour, then I put in the next blank.  I have done groups of 200 or more initially 1 at a time, then 6 at a time with 5 x 24 inch pieces.  


<br picture of a coping saw



 

wand store sign



 

 
          what fun to have thin stock.  lets see how this works

[doc henderson]

 

 

this is how we did it before the engraver.  they had a little ink stamp.  maple.  the corners were rounded on a belt sander.  note the walnut cookies on the steps for center pieces.



 

 

 

 

for metal there is a spray on ceramic coating, that turns to glass with the laser heat.

[JoshNZ]

Pretty cool Doc, we've just got a CNC table with a spindle so looking at similar stuff for my partner. Would sure like a laser to go with it.

When do we hear results of the 1/4" drying stacks, or is that what ended up as the coasters?

[thecfarm]

You will be The Yellowhammer of coasters!!  ;D

[doc henderson]

@JoshNZ



 

so already below 32%, who knows where it started.  I should have done a dry weight calc for the actual MC.  and maybe have a piece just setting in the shop to see how the airconditioned space with 320 M/sec. air and without does by comparison.  the edges are staying flat, but the other time did too until I undid the bundle (they did not have the air that time and were not dry).  you may have noticed but the top and bottom boards are 3/8th and that is the wood that is being tested.  that gave the internal 1/4 inch boards some protection, as the open top may dry faster on the open side.  I will try to do better on the next run/version.   >:(  

[doc henderson]

this is real time.  want to get industrial stock.  I put off doing projects if I have to make/process the wood for it each time.

[Crusarius]

Looks good doc. I have had some luck drying thin stuff. Definitely dries fast.

[doc henderson]

staying straight and drying fast.



 

 

this is at 24 hours with fan at 70° in shop, humidity at 40%

[Old Greenhorn]

Well that happened quickly! :D :D ;D ;D

[Crusarius]

I think I was happy with the dryness after a week or less. Biggest issue I had was crown. When I dried it I did not have any weight just sitting on top of the stack.

[doc henderson]

I give each clamp a squeeze and keep them tight.  at 7% I will dead stack but keep them clamped flat.  prob. make a press with all thread.  what do you all think would be the best MC to plane at.  too dry will chip.  I could do it now and then restack and dry some more.  I may drop my rollers on my planer so the wood is supported by the table and not up on the rollers.  I think that is why some of the thin stuff does not plane well.

[boonesyard]

I'd plane it now , will plane very well. Then dry it down as far as you're going to go with it. Even if it moves a bit more after you've planed it, which won't be much from 15%, it will all still be a uniform thickness. 

[doc henderson]

 

 

 

 

[doc henderson]

the thickness does not have to be a precise number, but thin as you mention.  the question is as the board gets thinner, will the edges and board get wavy?  want them flat.  @GeneWengert-WoodDoc  so what would be the ideal MC to plane them but not have them go all pringles potato chip on me.     at the lower mc, they could be dead stacked after planning.  i will prob. make a screw press to hold the 18 x 24 inch size boards.  may just store blanks in there.

[scsmith42]

Doc, I'm no Dr. Wengert but have dried 1/4" veneer material from green before. Here are a few things that I discovered.

1. Wood movement is closely related to grain structure. Sheets with varying grain tended to move more. Wavy edges occurred is there was much sapwood present. Sheets sawn with little to no sapwood dried flatter.

2. I used a much lower air speed than you. In my case it was 200 - 350 FPM, versus your much faster 350 meters per min. 

3. The sheets remained very stable after drying as long as I gave them a few days of continued drying after they reached EMC. If I destickered immediately after reaching targeted mc% they moved more afterward. An extra week of drying past EMC resulted in little discernible post drying wood movement.

Species that I've dried this way included white oak and sycamore.  I used 9" sticker spacing.

I've been told that there are special drying racks for guitar blanks. These look like the old egg crate style of fluorescent lighting grills except that the  egg crate is groves on both faces in one direction for air flow. Spacing on them is around 1" and they are 3/4 - 1" thick.

[Larry]

We turn lots of maple and cherry bowls from green wood to a wall thickness of 1/4" or less.  If in a hurry we microwave dry to 10% or less.  The warp stops at 18% but it will still shrink down to 10%. 

I would think for coasters anything less than 15% is good to go.

[doc henderson]

Thanks guys.  I appreciate all your comments and am considering them all and combined with my schedule, will plane soon, and restack to keep them flat.  too dry and the soft wood get brittle and chips out.  but I think I want it fairly dry, then it can all equilibrate in the dead stack.  after the coaster is cut, it will be tolerable.  if the whole sheet warps, then the laser is in and out of focus.  thanks everyone.  I find I get comments from Gene when his name is invoked, so there you go.  

[doc henderson]

so the planer chewed stuff up.  there tends to be areas with grain that is very intersecting, but as the wood thins, it self destructs in the area of the wild grain.  I could have lowered the rollers, but it is clunky on mine (reset them, not just a knob).  I then turned to my 24 inch drum sander, and it worked well.

[doc henderson]

I put together the next level of clamp using all-thread and knobs.  I made the clamps from left over oak stair treads cut 1.5 x 1.5 inches and 21 inches long.  everything is designed to make thin sheets 18 x 24 inches.  this fits the engraver and will fit in the heater.  



 

 

 

 

 

 

 

[K-Guy]

" That's the problem with you, Butch, your always thinking"  smiley_clapping

Well done Doc.

[Crusarius]

That is looking a little more than a fly by night operation. Nice.

[JoshNZ]

Quite the impressuve structure on its own haha. Would weight set on top of it not work just as well?

I've got a spiral head thicknesser arriving in October will be interested to see how well it works in comparison to knives in that regard.

My lady here has gotten into making coasters with funny covid quotes on them so I'll prob be doing something similar to this

[doc henderson]

I can pick this up and carry the whole stack.  it can fit in my fluid/blanket warmer so I can sterilize it if I want.  I will tape a second fan to reach the top of the stack.  I could make several sets, and stack them one on top of the other.  easier to handle.  when they are dry and sanded, I will dead stack them for later use.  21 deep, 24 wide, 36 inches tall.  prob. weighs about 20 pounds.  I had one thin one go wonky, but most are doing great.  I did not have it ready, so the thin sawn boards sat for a week and prob. started to dry on the edges.  overall pleased.  made some letter engravings for jimmy to frame as coasters,  did 6 across on a 4.5 x 24 inch strip of maple.  these will get 24 per sheet and the laser can do the shearing.

[doc henderson]

thus the reason for not doing the weight.  I can crank the knobs every 12 hours and still move the assembly.  I plan to make a wrench to tighten them, as the little knobs were giving me a sore spot.  (boo hooo).   I would love to hear about the spiral head.  I thought about dropping the bottom rollers on my planer, but it is too hard to readjust.  requires Allen wrenches, dial indicator and wrench to set a nut on the eccentric.

about 20 bucks for the hardware and another 20 for the all thread.

[Larry]

With my Byrd Shelix I can plane down to .040 than it starts munching.  It will vary a little by species.  Sounds just like somebody eating potato chips when it starts munching, no real drama at all.

When I saw veneer I usually stop planing around .090 to .060.

I want to try the wide belt and see how it does abrasive planing.  Might be better than the planer.

[JoshNZ]

You could make a false floor for your planer doc. I have made thin strips for accents in projects before and planed down to 1-2mm with success when knives are sharp (I had to because planer didn't go that low). It might be my own head telling me this but I feel like I had better success when the end entering was cut at a slight angle rather than square, so that the knives engage progressively rather than one board-wide hit.

All I did was clamp a piece of MDF to the in+out feed tables, large enough to cover it all. I might've waxed it too I can't remember. You could route away a little relief for your rollers (I had a lunchbox planer back when I did that).

[doc henderson]

my maple is not straight grained.  lots of figure and whirls of grain.  pretty but not great for the planer.  any grain that goes perpendicular to the face of the wood, cannot hold together, and flies into bits.  the 24 inch sander works well with 80 grit on front and 120 on back.  it has a wide belt to propel the sheet through.  I think the 18 inch wide makes the planer tough. and then the rollers that lift the ends, and I am sure the knives just bounce the center up and down.  I like the idea of the false bottom.  if my sheets were all the same size, I thought about a carrier board as well.

[metalspinner]

Doc Henderson
You should really look into a spiral head. The wood you just described would slide right through my grizzly 20" and come out perfect on the out feed side. It really is amazing. I think in the past 7 years, I've rotated the inserts just twice. The carbide really stands up a long time.

[Crusarius]

I spent $380 on a WEN planer with a spiral head. it has been a very decent machine for the price. It only has HSS cutters but still performs very well. I also plane a bunch of stuff that is very figured. sometimes I end up flipping the board around to run it through the other direction trying to take the fuzz off.

I have been very happy with it. may be worth investing in just for a cheap option.

[WDH]

You need a spiral head planer with the square carbide inserts.  

[Larry]

I should have put in my last post that I also use a bed board when planing the thin stuff.  Its just a melamine shelf board from one of the box stores.  I wax it with Johnson paste wax.  The melamine wears through pretty fast so I have to replace it every couple of years.

[Crossroads]

Looks like a good setup Doc. Thanks for sharing 

[doc henderson]

had to crank it down an inch today, so I need a wrench for the knobs or maybe a drill adapted bit to turn them faster.

[Ljohnsaw]

so I need a wrench for the knobs

You have a band saw or jig saw?  Take a piece of thin ply and cut out the shape of the knob to make a custom "box" wrench!

[doc henderson]

that is a good idea but of course I have to make it harder.  so I plan to photo or scan the knob, and then cut out layers on the engraver.  cannot make it too easy.  I may put a handle with a spinner, or adapt it to an impact.  the bar clamps held better, but it was hard to turn the little knobs on this as tight as I wanted.

[kantuckid]

Threads a tad "scientific"?  :D

If you cut thin, small dia. coaster sized cookies from Catalpa and made a set-up to sand them they'd air dry easily and that species almost never cracks to the heart. Plus it's got a nice lt brown tone too. I've used a bunch of it and never seen a crack-only some buggy stuff inside the logs at times. 
For coasters, given their small diameter when finished, there's also the notion to not fool with wide stock and it's inherent drying issues, especially when sawed thin and just table saw the thin strips then stack and dry them using bar clamps in an assembly of many pieces. 
 Some KS UV rays might do well to dry them fast? 

[doc henderson]

I think there is a sweet spot for thickness of a cookie, relative to its diameter.  I had good luck with 3/4 inch thick cookies 10 to 12 inches in diameter.  for 4 inch diameter, I do ok with 1/4 inch.  the motivation for the 18 x 24 inch size is it maximizes my equipment.  when I have a project i am busy working up material  I am trying to have stock ready, so if someone has a wedding,  I can pull 8 or 9 sheets and do 24 to 30 coasters per sheet.  each sheet will take an hours to engrave and sheer.  I have made anywhere from 200 to 400 coasters for each wedding I have done.  I started out making a 4 x 4 inch blank.  engraving and then sanding the corners round.  I am trying to industrialize the process for fun.  I could even engrave, sand the whole sheet, then sheer them in the laser.  I cranked down the threaded knobs another half inch this am.  the sheet that are about 1/4 inch are strait, a few that we close to 1/8th, are wavy on the edge. so there is also a sweet spot here too.  after sawing, I got busy and had to build the jig, so the thin boards sat for a week.  looks like this thin wood easily gets under 10% in about 3 days in the shop.

[doc henderson]

@kantuckid I love catalpa.
now that I have the jig, I think the key will be to saw it thin, put it right in the jig, turn on the fans and dry it fast.  dead stack it after sanding and clamp it flat.

[moodnacreek]

Thin boards dry too fast.  The way I have done it is to use thin dry sticks about 8" o.c. Thats a lot of sticks but without them real close the boards will buckle.

[doc henderson]

I started with the knobs at the top of the all thread, and now it has about 1.5 inches sticking out.  so that is the shrink on 34 1/4 inch on average boards.  the sticker are 1/2 inch tall and 1/4 inch wide.  they may have shrunk too.  I think if I tried to dry 1/8 th inch thick I would need many sticker or a mat like expanded steel.  I think my week delay in stacking also dried the edges some and made for a curve.  if I wanted that thin, I might even use blotter material and change, but may get mold.  I should have weighed the stack at the beginning and would have a MC and actual water loss calculation.  next time.

[doc henderson]

I find my finger getting sore turning the knobs to tension the clamp of the bolster.  so in addition to making a wrench or drill type turning aid.  as well the sharp edges of the oak bolster is rubbing as I turn the knobs hard.  (girls hands... not). so next time they are undone I will hit the edges of the frame with a 1/8th inch round over.

[kantuckid]

What I said. Maybe saw 1x4-5's on mill then dry on sticks and once dry revert to table saw for thinner work stock.  

[JoshNZ]

Hopefully you don't mind me pirating your idea doc, and you agree with what they say about imitation and flattery haha.

Not quite as impressive as your stack and a whole lot less elegant but same idea. I'll have to take my clamps back before they're dry I bet, and will probably end up just leaving some weight on it.

I wonder if it would be sensible to reposition the fillets after a week or so?

I found the perfect victim for it in my log stack today, a shattered log end I'd cut off with cracks, that fell into nice quarters I managed to quarter saw the lot from.



 

 

[doc henderson]

looks good, and it is a work in progress.  and yes, the idea is we share and maybe come up with more ideas.  stuff I might not think of, you may try and suggest.  my 3 foot stack has shrunk 2 inches in height.  I did work on the prototype wrench spinner.  I took a pic of the knob and then set the size equal to the knob after i got a line along the perimeter.  then I cut the shape.  the all thread is nice as clamps tend to want to fall off when things loosen up.



 

 

 

 

 

 

It fits well.  the knobs get wider near the base so the wrench is snug and does not go clear to the bottom.  ideas for the wrench or the one with a spinner handle (yet to be made) should make it easier to snug things up, like a clamp with great mechanical advantage.

[doc henderson]

the weight will work great if you have a spot it can set in.  it should dry in about 3 days with fans on it, then it can be dead stacked and stored easy.  you will have to snug clamps 2 times a day.  I did have the thought that a 4 foot stack would be good, as that would utilize all of the sir from a stack of 2 of the cheap box fans.  this stack is big and clunky enough, but I can pick the whole thing up and move it.  bigger could be moved with a 2 wheel cart.  I am encouraged that I can work up stock to maximize the efficiency of my engraver.  I should be able to do other things in the shop.  doing 6 at a time keeps me busy, working up thin stock as I engrave.  now I can do 24 to 35 at a time depending on the size.

[doc henderson]

you can see the black mold on the surface ot the top board, as it took me a week after sawing to get this stack, and next time I plan to saw and sticker within the hour.  I will get a beginning weight for fun.  it should be white.  the top board was about the worst.  I do not mind some spalting, and I expect much of that to sand off the surface.

[doc henderson]

the clamping jig is cheaper than buying 8 clamps and works well for 1/4 inch stock.  1/8th warped some, but may have done better if I had got it stacked sooner. 1/8th will require more stickers (closer together).  I have 4 rows of 1/4 inch wide and 1/2 inch tall stickers.  I could easily reproduce the jig.  I could use 3/8th inch couplers to extend the all thread to make a taller stack.  it is cheap, portable and works well, meeting all of my goals so far.  

[Ljohnsaw]

Doc,
Another suggestion.  See about getting some "die springs" or maybe salvage some rocker springs off an old engine head.  Put those under the knobs and it will keep more even pressure as the stack shrinks.  Then maybe you would only have to visit it once a day to keep it tight.

[doc henderson]

I could go cray cray and make a connected group of cogs. so turning one turns them all with a weighted lever (like a coocoo clock).

[scsmith42]

Doc,
Another suggestion.  See about getting some "die springs" or maybe salvage some rocker springs off an old engine head.  Put those under the knobs and it will keep more even pressure as the stack shrinks.  Then maybe you would only have to visit it once a day to keep it tight.

John beat me too it, as I was also going to recommend stiff springs under your knobs. Due and valve springs are both great choices. Valve springs typically have 125-150 pounds of force each.
They will help to provide consistent clamping force in-between tightenings.

[doc henderson]

or pneumatic cylinders or and air bag under the top.

[doc henderson]

work is going well,  the 7 inch spacing is good for 1/4 inch rough, but too far for 1/8th inch thick.



 

 

 

 

 

 

 

so the thin sheets are working well,  24 coasters per sheet.  had to slow the vector stuff down to get all the way through.  moved the lines in to get a brown sear mark all the way around the edge.  a sheet takes an hour so I can set a timer and do stuff around the shop.  even some mistakes when the optical strip got smoky and were off a bit, can turn over and make a nice coaster on the backside.  

[metalspinner]

Doc Henderson
Did you mention what kind of laser you have?
I have an inexpensive Ortur and there's no way it will burn through 1/4". 

[doc henderson]

the first prototypes were 1/4 inch, and the "spinner" is 1/2 and took several passes.  species matters as well.  less dense requires less.  if there is a knot, it may not make it through all the way.  It is an epilog helix, with a 60 watt laser.  18 x 24 inch table.  has a rotary attachment and can do a good sized growler.

[doc henderson]

It is working well.  have about 350 in Q, and 100 done.  these are for my friends sons wedding.  



 

 

 

started working on some for a local winery.  yes a local winery.  keeping it simple.  he will have tastings and wants souvenirs for patrons of the tasting.  we will do glassware, charcuterie boards, coasters and wine glass hangers.



 

 

 

 

spalted maple, ERC, and walnut examples are mocked up for him to look at.  He is a local orthopedic Doc. about to retire and do the vineyard thing.

[Don P]

Reading this it kicked off memory from a small shop years ago. In small scale panel glueup the rig looks similar to yours. The cauls, your top and bottom bolsters, are slightly bowed so that they provide uniform contact to the center of the panels as well as the edges. The degree of curvature is black magic as far as I know. A torque wrench or impact wrench on controlled pressure is used to run the rods (nut on the biz end welded on), tight so they are clamping with uniform pressure.

[doc henderson]

I have thought about a center bolster perpendicular to add some pressure to the center line.  the knobs were hard to turn, but once they started, I could do 2 or 3 revolutions.  so I made the wrench and will try to use length of rod out the top.  I am getting ready to start the next batch, and one thing I want to do is stack them right off the mill.  I was recently given an old style rod type torque wrench, and I may try that.  thanks Don.

[Old Greenhorn]

Bryan, try putting some never seize on those threads to give you a more accurate torque reading, get the stuff with the copper in it. Restarting a nut already under load shows a false torque reading because of the existing load which is comprised of mostly friction. Never seize will minimize this quite a bit.

[doc henderson]

thanks Tom!

[JoshNZ]

Are you sure you need that much pressure doc? Sounds like you're putting some serious force on them. Are they showing signs of cupping without it?

[doc henderson]

still experimental.  some still cup, but you need to flex them the other way for a bit if so.  I think the idea was not to force them so much as to make them uniform.  I can also do that with the number of threads and or length of all-thread showing.  I started at 0 or 1/4 inch and wound up in three days at 2 inches.  

[JoshNZ]

I haven't even looked at my clamps. You're being a lot more vigilant than me haha.

I ended up with a small slice off a quartered cant the other day and it was about the size of this coaster stock, and I just laid them in the handles of the clamps haha even they haven't cupped.

[doc henderson]

getting to the industrial scale I am looking for.  working with another doc that is about to retire from ortho and has a good start on his vineyard and wine business.  Wedding coasters are coming along nice.  about 200 done.  I can finish using the heater about 96 at a time.  I could add more shelves.



 

 

 

some charcuterie boards and a 2 foot sign with his font and some logo ideas.