Best technique for smoothing end grain cutting boards ?

[chainsaw_louie]

A friend recently moved to Costa Rica started a project to make round cutting boards of disc's cut from Cocobolo logs.  Without doing a prototype, he arranged for a local tree man to provide some discs which will be cut from Cocobolo logs with a chainsaw.  The tree guy enthusiastically cut and delivered 400+ discs , 5/4" thick x 10-14" diameter. 

Now the hard part...my friend discovers that although the discs are rather uniform in thickness,  the scars and gouges left in both sides of the cutting board disc's by the by the chainsaw are up to 1/16" deep. 

He further discovers that Cocobolo wood is extremely hard and end-grain is especially hard to cut. He tries sanding but it takes hours to finish one side.  A wood planer is definitely out of the question.  I suggested a 1/2"router in a  XY sled and a end cutting bit. 

Has anyone found a good solution for making end grain cutting boards?

Thanks !

[Magicman]

Your friend is on the verge of learning an expensive lesson.  The cookies should have been sawed/bucked with a bandsaw with probably a carbide/tungsten, etc. tip blade. 

The next lesson is that unless they were sawn from a very dead/dry log, they are probably going to split.

[doc henderson]

A drum sander gets them close.  It does not chip out the backside like a planer would do.  We have several threads on cookies.  Yes, if cutting with a bandsaw mill, the thickness will be uniform, and less sanding is needed.  To reduce the splitting, the cookies need to dry slow.  We add wax or sealer to log end, because the end grain is open and water leaves fast.  this is why we get splits on the end of logs.  a cookie is a very short one-inch-long log.  If they started from live trees, they have a lot of water loss and shrinking to happen.  I have tried soaking in denatured alcohol and that helped.  you can also stack them close to reduce water loss rate.  you can also put them in a box or under sawdust. 

[doc henderson]

walnut cookies 1 inch thick x 10 inches diameter in a box.





stack of walnut after soaking in a 30-gallon barrel of alcohol.




24-inch walnut cookie.  sapwood got splits.  mount for a European prep of deer.



Maple holiday fun, they all split with no prep.  various sized 14 to 10 inches 2 inches thick.



cottonwood disc 28 inches diameter and 2.5 inches thick.  forgot about for years in my container.  on got a little split, but not this one.






Friends from the Children's Hospital in prep. (helping) finishing the walnut center pieces for a wedding.  we made 55.  We used Danish oil.  did not like the gloss of spar urethane, and this was faster and cheaper.

[Old Greenhorn]

Your friend has some expensive firewood there. Sorry.
 I made that mistake too when first messing with cookies in RO. You can use a hand belt sander to work on them and eventually get a smooth surface, but getting the front and back parallel is very difficult. All cookies will crack at least some unless you remove a disc of material in the center.
 As MM said, cut them on a band saw for best results and least sanding. Any blade will cut them, but carbide will likely be the smoothest cut. A drum sander will flatten and smooth with the least effort. Perhaps he is somewhere near @teakwood in CR? If so, maybe Ramon could help him out and also cut some out of teak.

 End grain cutting boards are usually made from kiln dried wood cut off the end grain and glued up as composite builds. Mostly this is done because of the cracking issues,
 Best of luck to your buddy.

[doc henderson]

the tendency to crack is a physical thing.  A log or cookie shrinks as a percent of circumference.  so, the outer parts shrink more than the inner.  that is also why the outer part of the crack is wider than the inner.  One crack to the center and the stress is relieved.  It also matters the species and diameter relative to thickness.  He can fill the crack with epoxy or wood wedges, or bowtie inserts, but all take time and money.  For high end (money) it might be worth it.  If they are going to be cheap touristy items, may not make sense to put in lots of time.  If labor is cheap it might work.  It took 5 gallons of alcohol for my 55 cookies, and also time to dry in a box.  400 should take at least 40 gallons, and the cheapest I could find was 30 bucks for 5 gallons.  I prob. have 400 cookies around, just waiting years for a project.

[doc henderson]

I still have some of those cookies and a few have faint cracks in the sapwood but overall are stable.  

[chainsaw_louie]

When I spoke to him yesterday and asked about cracking, he said only a few have split.  They must have come from dry logs.  

I think his #1 issue is removing even a small amount of the very dense and hard cocobolo wood which at 2960 on the janka scale is definitely a hard wood .

1300	Spalted Beech
1320	White Ash
1320	Curly White Ash
1320	Swamp Ash
1330	Shedua
1335	Quarter Sawn White Oak
1335	White Oak
1350	Ebiara
1360	English Brown Oak
1400	Mayan Walnut
1400	Eucalyptus
1439	Quilted Sapele
1450	Birdseye Maple
1450	Hard Maple
1450	Curly Hard Maple
1450	Quarter Sawn Maple
1450	Bark Pocket Maple
1450	Hard Maple Burl
1450	Spalted Maple
1450	Rift Sawn Hard Maple
1460	Madrone Burl
1500	Sapele
1520	Canarywood
1548	Honey Locust
1560	Afrormosia
1712	Merbau
1780	Black & White Ebony
1800	Camphor Bush Burl
1800	Figured Camphor Bush
1810	Afzelia Burl
1820	Hickory
1830	Zebrawood
1830	Figured Zebrawood
1860	Jarrah Burl
1878	Yellowheart
1900	Red Palm
1930	Wenge
1960	Bolivian Rosewood
1970	Padauk
1970	Ziricote
2010	Bocote
2020	Black Palm
2140	Sucupira
2150	Leopardwood
2160	Goncalo Alves
2200	Chechen
2200	Honduras Rosewood
2200	Honduras Rosewood Burl
2250	Orangeheart (Chakte Viga)
2318	Spalted Tamarind
2400	Osage Orange (Argentine)
2400	Santos Mahogany
2410	Figured Bubinga
2410	Quilted Bubinga
2410	Bubinga
2430	Cochen Rosewood
2430	Indian Ebony
2440	E. Indian Rosewood
2480	Tamboti
2490	Red Mallee Burl
2490	Brown Mallee Burl
2500	Tulipwood
2520
2720	Madagascar Rosewood
2760	Osage Orange (USA)
2900	Bloodwood
2920	Yellow Box Burl
2960	Cocobolo
3000	Mun Ebony
3080	Gaboon Ebony
3080

[doc henderson]

On that scale he will need a drum sander and experiment with different types of sandpaper and grit.  the splitting is inevitable and if they were wet, they will likely all be split in a few weeks.
It can be fairly humid there, so may not dry as fast.

[Resonator]

Finding a cabinet shop that would have a full size abrasive surfacer would be one place to start. Take light passes and see how they smooth out. Another option would be to find a shop with a CNC machine. Then they could be flattened like a router sled, just in a more automatic fashion. Like a lot of problems, they can be fixed, just how much money it costs to do it.

[Larry]

About 30 years ago a shop teacher asked if I could saw some cookies for him out of walnut. He taught shop to younger kids and for a project they made clocks out of the cookies. Simple project but he was in a poor school district and didn't have money for the cookies from commercial sources.

I took on the project as I was sawing lots of grade walnut and I could get the cookies from limbs and waste. Made a jig to hold them on the sawmill similar to Doc's and had at it. What I found was if I sawed the cookies at an angle cracking went way down. With walnut I hardly ever lost one to cracks. The shop teacher was from Kansas and over maybe 5 years I probably sawed enough cookies for every kid in Kansas.

Much later I sawed a few cookies and processed them to kiln dry and finish sanded. Started with a Grizzly drum sander and hated it. The sandpaper would load up especially on the sapwood or burn really easy. I tried the planer with a Shellix head and that worked pretty good with small bites. A few years ago I got a small widebelt sander and that works great on the dry cookies.

[doc henderson]

I have used a hand planer, but you have to work in a radial pattern from outside to middle so you do not chip out the edges.  the drum sander gets them flatter than a belt sander, but you do have to keep the sandpaper clean, or it will burn and put some grooves in the work.

[tule peak timber]

I have never had any luck using planers of any kind on end grain. Grinding, sanding are the only ways to go. In a pinch you can get by with a hand held belt sander, but you really need is a full on wide belt sander. 

I'm just getting ready to start a job with live oak and cork oak cookies and I'm expecting lots of shrinkage and loss. My answer is to just cut more of them and cherry pick the better dried stock to work with for furniture making. I explained this to the client and they will expect some cracks and voids that will be filled with pieces of wood (inlay) or bark from the original tree. I haven't tried the alcohol method yet for drying, but have used stacked, stickered piles of cookies on a pallet, then bury the whole thing in sawdust with some success. I've done this on olive and walnut cookies.