drying thin wood for coaster stock.

[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.

[NewYankeeSawmill]

The more I see you post stuff Doc, the more I want one of those laser engravers....
They'll shoot just about anything, not just wood, correct?
I've got a 10 Watt from an old film image-setter lying around, I wonder if I could... 

[doc henderson]

I had a PM and replied but may as well add it here.

Well, thanks and I will add a few things.  You will have to experiment with how well different species plane and what MC is best.  If you plane wet and still have to dry, thinner material will tend to warp more given a set sticker placement.  stickers need to be smaller and closer for any thin material and get more so the thinner it is.  so, what thickness to mill at, will be determined by how it planes.  may be better to plane after it is dry, but species like ERC and maple may chip out some in chaotic grain.  the helical is great but there is a limit to thickness that is species related.  knots and swirls are great to look at but not if they are all in your dust collector.  a drum sander to finish is still a good option followed by ROS.  If you set your engraver to cut 1/8thinch and hit a knot or harder wood, it will not make it all the way through.  you will waste some time effort and material, so I suggest you start a notebook and make ref. to speed and power setting vs material.  it is great on canvas and paper.  we have done notes in Christmas cards, and ID on the front of notebooks.  My current maple is milled and dried at 5/16ths.  planed the drum sanded, then random orbital sanded.  My bed is 18 x 24 inches, and I try to make blanks this big, so I can do it as a sheet of say 24 coasters.  I have been doing some acrylic and it is better than I thought for photos, not just line art.  my standard for coaster is just under 4-inch square.

Not sure pine will engrave well as the grain burns much darker than the wood between.  not good for grayscale and photos.  I have engraved ERC and is good for line art, plaques and text.  Mine will cut 1/2 inch in theory but may take several passes and adjusting the focus closer.  I get my coaster that I just cut out to 1/8thinch.  I have a friend that likes to frame them with walnut and puts felt on the back.  he will add a backer to make them 1/4 inch, and that is why I am now at 5/16th so he does not have to do that.

Maple and cottonwood have been good for photos as they are white and fine grained.  they burn at a range of brown, so you get lots of different detail in a grayscale photo.  Walnut as an example is already dark brown as is the engraving.  sometimes it is hard to read even text on walnut. 

I assume you have seen the drying setup I made for the 18 by 24-inch stock.  If not, I can add photos.  Doc.

[doc henderson]

plain cut out coasters for the masses.  



walnut framed



Mesquite framed maple



felt backing.

[doc henderson]

photo on acrylic of my friend's son who passed away.

[plowhog]

Doc, have you ever tried treating pine or similar woods before engraving? Would treatments help even out the darkness in the grain vs other areas?

I've heard of spraying first with lacquer, or applying a Borax solution to the wood first, for a darker engrave. 

I have not tried pre-treatment. Only masking, laser through the mask, and a quick coat or two of paint to make it pop.

[doc henderson]

If you mask and then paint inside the engraved area within the tape yes.  If you engrave pre-finished wood the engraved are would still darken the grain quite a bit, I think.  If you pre-finish a project, it means you can wipe off the smoke and not have to sand it off.  Give it a try and post pics if you can.  the issue is the grain will be much darker than the surrounding wood and disrupt a photo.  I did some wood engraving for a fellow FF member as auction items to raise money for a reunion they have.  the wavy grain in I think maple really added to the pic, as it was at sea.

[plowhog]

The image of 3 elks is on cedar wood with varying power settings. No pre or post prep.

For the rope graphic image, I masked the cedar with tape, engraved, then used two coats of black spray paint.

The H image is on black oak with no special prep and no post-engrave changes.

I have not tried engraving pine yet.

[Note: this reply got added to a different thread by mistake due to a network error during posting. Not sure why .... ?? ]

[doc henderson]

found it.  DD725 destroyer.  the grain made the sea look nasty and tough.  I thought added to the overall feeling of excitement, looking at the image/art.

 


In the ERC the grain is prominent.  It almost looks like the sea and waves have a horizon of straighter grain above. 

in the maple the edge grain that is chaotic makes the ocean seem more violent.  the chatoyance looks like reflection off the water.  helps to have a beer or two before looking as well. 

[plowhog]

I've now begun experimenting with thin cut ponderosa pine. My goal is to create dry, thin stock my laser cutter can work with.

Built a special pallet with bolsters every 6 inches. Then milled an old log at about 3/8" thickness. It was an old, junk log that didn't yield much, but it is enough to at least start a trial. I stacked what wood I didn't throw away, then put a fan on it.

If it dries reasonably fast and can survive planing, it should become usable for a few different projects. I'm going to mill up a better log to add to the pile of thin lumber, plus I need to make some of the "tiny" stickers. 

[doc henderson]

Plow did you say you reviewed my other thread?  and saw my clamp rig?

[Brad_bb]

I was gonna say a drum sander might fare better with thin stock.  But you got that covered.

Do the coasters stay flat longterm?  Does the finish block the moisture form the drink well enough?  I was wondering if they coasters reabsorbed enough moisture to make them warp.  I guess it's less likely because if dried down low enough to remove the water in the cell walls, less likely to warp in future.  Captured water is the term I was looking for versus free water.