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Other topics for members => General Woodworking => Topic started by: chainsaw_louie on April 27, 2025, 08:31:42 AM

Title: Best technique for smoothing end grain cutting boards ?
Post by: chainsaw_louie on April 27, 2025, 08:31:42 AM
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 !

IMG_2039.jpeg
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: Magicman on April 27, 2025, 08:47:55 AM
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.
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: doc henderson on April 27, 2025, 08:55:03 AM
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. 
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: doc henderson on April 27, 2025, 09:01:28 AM
(https://forestryforum.com/gallery/albums/userpics/51041/624422BD-4965-4C16-AE59-FBCB0F359FCD.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=258491)

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



(https://forestryforum.com/gallery/albums/userpics/51041/7D73016D-285B-4336-A0B3-431D89D7884A.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=258500)

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


(https://forestryforum.com/gallery/albums/userpics/51041/079.JPG) (https://forestryforum.com/gallery/displayimage.php?pid=258405)

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

(https://forestryforum.com/gallery/albums/userpics/51041/5EC29048-7140-4426-81CD-44626C3B0AFF.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=266389)

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

(https://forestryforum.com/gallery/albums/userpics/51041/00D1461E-4352-401F-B259-1A7706E7A9E7.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=260941)

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.



(https://forestryforum.com/gallery/albums/userpics/51041/6D6CF4ED-B88E-472C-B2B6-1E1020C27835.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=260020)


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.

(https://forestryforum.com/gallery/albums/userpics/51041/957724ED-8002-42F1-B437-0C5C2FEF03BC.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=260590)
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: Old Greenhorn on April 27, 2025, 09:23:18 AM
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.
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: doc henderson on April 27, 2025, 10:11:33 AM
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.
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: doc henderson on April 27, 2025, 10:17:29 AM
I still have some of those cookies and a few have faint cracks in the sapwood but overall are stable.  
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: chainsaw_louie on April 27, 2025, 12:05:42 PM
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 .

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Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: doc henderson on April 27, 2025, 12:19:04 PM
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.
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: Resonator on April 27, 2025, 12:35:50 PM
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.
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: Larry on April 27, 2025, 04:01:05 PM
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.



Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: doc henderson on April 27, 2025, 05:18:53 PM
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.
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: tule peak timber on April 28, 2025, 09:30:16 AM
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.
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: gspren on May 25, 2025, 05:52:54 PM
As an old machinist my thoughts would be to put them in a metal cutting lathe and face cut them, but what do I know about wood cutting?
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: chainsaw_louie on June 05, 2025, 09:04:31 AM
Update from my friend in Costa Rica:

An expensive, imported Milwaukee router and end cutter were purchased .
Then a local fella fabricated a router sled.

He says this works perfectly to cut an even and smooth face on the cookie.

The picture shows his 18 year old apprentice:

IMG_9538.jpegIMG_9537.jpegIMG_9548.jpegIMG_9552.jpeg
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: chainsaw_louie on June 06, 2025, 08:56:56 AM
Only a few of the discs are free of shrinkage cracks.  Due to the shape and the way moisture moves in and out of the cutting board , is there any way to fill these cracks with material such as epoxy resin, that won't fall out ?  It seems that a flexible filler such as butyl rubber caulk would be  the right solution except that it wouldn't look good or be food safe . 
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: doc henderson on June 06, 2025, 09:09:53 AM
some penetrating low viscosity epoxy would make it a fiber reinforced plastic and a contrasting color or black would work to fill the crack.  could even mix it with sanding dust to make a paste.  many of these tricks were shared by @tule peak timber 
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: tule peak timber on June 11, 2025, 04:37:25 PM
Just making some end grain edge banding today with penetrating epoxy. Wood flour and epoxy for fill. :thumbsup:
Title: Re: Best technique for smoothing end grain cutting boards ?
Post by: tule peak timber on June 12, 2025, 03:26:51 PM
End grain walnut with penetrating epoxy. This is all the same material in different phases.