Cutting crotch wood
Details on the right equipment and techniques to get the job done. March 4, 2002
When cutting crotch wood, what is the best way to proceed? I am interested in making tabletops from crotch wood and natural edge wood for tops.
From contributor P:
I have no idea what machinery you own, but here goes:
There are two practical ways to cut crotches. The money required varies greatly between the two methods. Very large bandmills can do it. You would need a big-bucks machine to do it that way. The other route, which is affordable at the hobby level, is the chain saw mill.
The chain saw mill is available at three basic price points, represented best by:
Granberg Alaskan mills with a chain saw, $1000 to 1500.
Hud-son mill costs about $1,800, plus a good chain saw engine.
Lucas or Peterson slabber mills in the $10K plus range.
These cover most of the possibilities regarding the cutting.
After the extensive drying period, there are basically two approaches to surfacing and sanding such crotch slabs. The first approach would be the use of a belt sander with a random-orbital sander as follow-up. Cost here is under $300 for tools. The second approach is to buy a hefty used thickness sander - a huge one. For a hefty multi-thousand dollar price tag. Such a machine will flatten and sand the slab.
When cutting crotches, the area below the Y in the crotch has a swirl that the hobby or table clients want. Cutting it is done in a through and through cut if your mill can cut the width. If not, you have to cut the two ends of the Y's off to make your width of crotch to cut on the mill. Drying is a lot harder because of several different grains of lumber. PEG or end grain seal is what I use to slow down drying. Also, you get mirrored boards that this type of customer seems to like.
I have also heard of people building a jig to run a router at a fixed height with the crotch under it to take a face cut or two off the sawn crotch.
From contributor P:
The above technique is covered in an old issue of Fine Woodworking magazine. If you have access to a really good woodworker's store that has the Fine Woodworking books by Taunton Press, you might find this tech. The article included a design for a guide frame. The tech was called "surfacing with a router" or "router/surfacer"? Also, this magazine publishes an index periodically to organize their huge volume of useful tricks. You can buy these indexes or see them in the magazine issue in which they first are printed.
I have a leveling unit I built. It begins with a 5' square made from 1" x 1" angle iron. Where the ends join I simply put a 3/8s bolt to hold it together. I then made a rectangle from the same kind of material. It measured approximately 5' one way and 18" the other. On each end of the rectangle I bolted two grooved bearing rollers that fit on the edges of the 5' square. This then moves only one direction, forward or back. Within the rectangle I designed a holding bracket, to which the router is attached. This framework also has 4 rollers attached as before that rides on the edges of the rectangle. This can move from left to right or right to left while the rectangle can move forward or back towards you as you operate the unit.
When I cut crotch wood on my bandmill, I shim the log so that all three piths are the same height off the deck. This enables me to box the heart out in one slab, giving the other slabs less chance of heart split or checking.
Which way would the log lie, with the two one on top of the other or side by side?
Lay it so you get Y shaped boards.
From the original questioner:
I have a WM LT-30. It is a 1986 model but it cuts great. I am seeking knowledge on proper sawing and drying of crotches and slabs for rustic tables, benches and mantles. I have no other special equipment other than a forklift, tractor and hand power tools. Around here it seems like the less you do to the wood the more it brings. Can't seem to make any money sawing pine with the flood of beetle pine being sawn.
I've had the best results, when drying crotch wood, after sealing the ends with wax end sealer. Then apply pentacryl generously over the entire crotch. This pentacryl (a type of wood stabilizer) is used by wood turners to keep their bowls and such from warping and cracking. I just "air dried" a black walnut crotch I cut last year. After sitting for a year stickered, I don't have any cracks or warp to speak of.
I have good luck simply coating the entire piece of wood with Anchor Seal. This is on walnut, western big leaf maple, and western Oregon white oak.
I have been cutting slabs with the slabbing bar on a Lucas mill for 3 months now. This includes oak, elm, sycamore, ash and beech. I am boxing the heart, fully expecting to cut out the heart and join. The slabs on top and below are the prize slabs and the rest I mill for legs and beams.
My father has researched the construction technique for making slab tables from the ancients and it's not straight forward, by any means.
I will be using the Lucas mill as the perfect square flat milling platform using a router bit mounted on the engine - a 25hp router. Likewise for the primary sanding. The final sanding will use the largest helicopter and belt floor sander I can hire.
This I have identified as a particularly good growth market. I have done no marketing and already 11 clients. That's about 2 years work. I have the monopoly in this country as no one else can or is interested in the capability. Drying is the key, though, and I believe a large vacuum kiln is essential. Otherwise you're waiting for years to get it to a workable condition.
Careful though - the underside bracing against warp and cup are the most testy problems.
From contributor P:
What woods have you been able to really cash-in on that normally aren't attractive commercially? Especially woods in the southeastern US.
I have sawn red mulberry logs here in NC, and the resulting wood is very good looking, bright yellow when fresh, getting more of a russet color over time. Whether or not it will sell, well, I'll know more once I get it dried.
Red oak grows rapidly here, and I have sawed pieces 40" wide out of complex crotch sections. I got the crotch and butt log because the sawyers working the job didn't want to mess with it - too large.
Here in NC we are kind of borderline for maple, but you can get some occasionally. Elm can be stunning, if difficult to work with. Currently I am working with wormy maple (from Ohio), which is not used by production furniture companies, but sure is awesome when you build something out of it - very unusual markings.
Eastern red cedar turns up - I saw slabs out of the logs to separate my work from the 1/4" - 1/2" thick pieces available commercially. Also interesting is osage orange, paulownia, sassafras, dogwood, holly and whatever else one can cut up and dry.
I get an occasional Kentucky coffee tree or coffeenut as some call it. It is real pretty grained, about like ash but it has a reddish tint. I could just about make a living sawing sassafras if enough woodworkers had a knowledge of the wood. I am getting ready to saw a burr oak that was almost 6' on the stump. Lightning split it down the middle so I only had to cut two halves to quarter it.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
I live in central Texas and also make natural edged slab top tables. I use mesquite and eastern red cedar rough cut 8/4 and planed on a Woodmaster 725. After planing I use the drum sanding attachment to finish the surface with good results.
Comment from contributor B:
I live in the US Virgin Islands and there are a lot of mahogany trees here that get blown down by hurricanes. All I have is a Stihl 44 magnum chainsaw and I've been cutting crotch boards with no jig. I just stand the crotch up and cut the boards the width I want, as long as the crotch log is no longer than 6 feet. I just cut a mahogany crotch log 48 inches wide, dry it and then hand plane it, belt sand it and orbital sand it. I use crotch boards for tables I build. Though it does take practice, I can cut very straight. The planer makes up for the rest.
Comment from contributor C:
I have been working with crotch woods and burls of white oak, particularly bur oak.
About the vacumn drying mentioned above, yes - it is a definite plus if you are trying to make any money at this. Thing is that one vac (at least the one that I made) will supply enough materials for 6 persons, so one is a bit much for just one guy. Seems the best way to get started might be to purchase woods from someone who has one, then as business grows, buy one. Manufactured ones are pretty expensive, but I built mine for about $5,000.
Here is what a vac does for me.
1) Increases the speed of customer delivery for custom works.
2) Decreases the need of space, roofs, buildings, etc. for the storage of large inventories of drying or dry woods.
3) Provides a degree of control over drying. Or better said, stabilizing that you can get no other way.