Milling QS red oak slabs for "Roubo" style workbenches

[Scott T Smith]

This past weekend fellow Creeker David Keller NC and I hosted an event at my farm in North Carolina to mill up some quartersawn red oak slabs for "Roubo" style workbench tops.

I had a 14" thick, 48" x 72" red oak slab that I milled several years ago tucked away in the corner of my shop, and last December David and I offered to mill it into QS Oak workbench slabs for members of our local woodworking club. The resulting slabs came out around 24" wide and 4.5" thick.

My sawmill is a Peterson WPF model that can mill logs up to 5' in diameter, and David has a Granberg Alaskan chainsaw mill with a Stihl MS660 driving it. We used both mills, as the maximum width board/plank that I can yield w/o turning the log is 20".

In addition, I had a 50" diameter, 16' long red oak log sitting in my log yard which we set up to be milled for future thick bench tops. Because of the significant weight of the log (over 10 tons), I used a crane to set it into place. I'll probably mill it in the next week or so.

A number of members of our local woodworking club were on hand to assist, and we all had a great time.

Here are some photo's of the action:

Setting the slab up for milling:

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Splitting the 48" wide slab into two 24" slabs with a chainsaw:

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Setting one slab up on top of the other for milling:

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Making the initial cuts with my Peterson sawmill:

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Milling out the portion between the Peterson cuts with the chainsaw mill (David Keller NC is the one in red on the right).

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One of the milled slabs:

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Picking up the 10 ton red oak log with a crane in order to move it into the sawmill:

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Measuring and aligning the pith of the log parallel to the sawmill tracks and carriage.


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Any time that a bunch of woodworkers get together to make sawdust it is bound to be fun, and this event was no exception. It was even more rewarding since were were producing something that was extremely rare - 4" x 20+" wide plank quartersawn oak workbench tops!

David took one of the slabs home with him, and I look forward to seeing some photo's of the workbench that he makes from it.

[Ted Calver]

Very interesting. The blade on that Peterson looks scary! QS oak should make some nice bench tops. Shoot a couple of book matched 2" slabs would make a great dining table. Thanks for giving us a look at your operation.

[Stephen Pereira]

Wow.. that is one heck of a log!! Very impressive. One question come to mind..how are you going to dry those slabs?

[Scott T Smith]

Wow.. that is one heck of a log!! Very impressive. One question come to mind..how are you going to dry those slabs?

Stephen, the bench top slabs that were milled from the 14" slab are already fairly dry, as the 14 incher has been air drying for about 3 years.

The ones that I mill from the big red oak log will be initially stacked and stickered in one of my barns, and I'll either air dry them for a couple of years and then run them through my DH kiln to finish them off, or I might get industrious and build a vacuum kiln sometime later this year.

The nice thing about quartersawn slabs is that, even if you build a bench green from them, they won't distort that greatly during the drying process and they can be re-flattened as needed.

[Derek Gilmer]

Stephen, the bench top slabs that were milled from the 14" slab are already fairly dry, as the 14 incher has been air drying for about 3 years.

The ones that I mill from the big red oak log will be initially stacked and stickered in one of my barns, and I'll either air dry them for a couple of years and then run them through my DH kiln to finish them off, or I might get industrious and build a vacuum kiln sometime later this year.

The nice thing about quartersawn slabs is that, even if you build a bench green from them, they won't distort that greatly during the drying process and they can be re-flattened as needed.

Seems like in one of the discussions of the Roubo benches it was mentioned a green slab was ok if not preferred. They made sure the warping would push the center of the top up. That way it tightened the entire assembly at the leg joints and could easily be planed back to dead flat.

[Scott T Smith]

Seems like in one of the discussions of the Roubo benches it was mentioned a green slab was ok if not preferred. They made sure the warping would push the center of the top up. That way it tightened the entire assembly at the leg joints and could easily be planed back to dead flat.

Derek, I recall the same as you regarding using a green as opposed to dried slab. If I recall correctly, that would mean orientating a flat-sawn slab so that it is "bark side down", or when viewed from the end the growth rings are "smiling" instead of "frowning".

[Van Huskey]

That is some serious wood porn!

[Dave MacArthur]

Don't know why I forgot to comment when I read this last night, but this sounds like a seriously cool day! I'd love to see some pics of a bench made from one of your slabs, and hope someone posts one!

[James White]

Scott,

If you do wind up building the vacuum kiln. Please be sure and share as much as possible with us. I have a home built DH kiln. But would love to do a vacuum kiln.

James


Stephen, the bench top slabs that were milled from the 14" slab are already fairly dry, as the 14 incher has been air drying for about 3 years.

The ones that I mill from the big red oak log will be initially stacked and stickered in one of my barns, and I'll either air dry them for a couple of years and then run them through my DH kiln to finish them off, or I might get industrious and build a vacuum kiln sometime later this year.

The nice thing about quartersawn slabs is that, even if you build a bench green from them, they won't distort that greatly during the drying process and they can be re-flattened as needed.

[Mike Wilkins]

Nice looking toothpicks Scott. I have been reading some of your posts on the NCWW site, and hope to someday visit your facility to get some lumber for myself. Have fun and stay safe.

[Scott T Smith]

Nice looking toothpicks Scott. I have been reading some of your posts on the NCWW site, and hope to someday visit your facility to get some lumber for myself. Have fun and stay safe.

Mike, you're welcome at any time. We're having a lumber run on Saturday March 5 if you can make it. There will be some zebrawood, african mahogany (although most of the mahogany is spoken for), and I'll have both red and white QSO available at a discounted price.

[Scott T Smith]

Scott,

If you do wind up building the vacuum kiln. Please be sure and share as much as possible with us. I have a home built DH kiln. But would love to do a vacuum kiln.

James


James, will do. There appear to be several challenges associated with building a vacuum kiln, primarily having a strong enough vessel and secondarily the system for getting heat into the wood and chamber. I have some surplus 500 and 1000 gallon propane tanks that should be strong enough not to collapse (and all of the welding equipment required to convert them), but coming up with a simple, effective and relatively inexpensive heating option has alluded me thus far.

[Danny Hamsley]

Scott,

You handle some seriously big wood, dude! Very impressive. I would love to see some pics of the big red oak log during and after milling.

[Andrew Gibson]

OK, I love my club, but being one of maybe 4 members under 55, and one of maybe 2 under 30. I am in the Wrong Club!

[Derek Gilmer]

James, will do. There appear to be several challenges associated with building a vacuum kiln, primarily having a strong enough vessel and secondarily the system for getting heat into the wood and chamber. I have some surplus 500 and 1000 gallon propane tanks that should be strong enough not to collapse (and all of the welding equipment required to convert them), but coming up with a simple, effective and relatively inexpensive heating option has alluded me thus far.
Could you build a solar kiln around them? Perhaps paint them flat black and put some silver reflective material on around the sides/bottom with a clear cover over them?

[Scott T Smith]

Scott,

You handle some seriously big wood, dude! Very impressive. I would love to see some pics of the big red oak log during and after milling.

Danny, it's a "Texas" thing, what can I say?!

I'll be sure to take pix and make a new post. That log is very clear, we'll probably be able to yield some "FAS" grade quartersawn workbench slabs.

[Scott T Smith]

Could you build a solar kiln around them? Perhaps paint them flat black and put some silver reflective material on around the sides/bottom with a clear cover over them?

The short answer is that I'm not sure. As I understand it, temperature does not transition well though a vacuum (think space), however many vacuum kilns use convection to convey the temperature up into the wood from heat exchangers installed in the lower half of the kiln. Thus, there is a missing link here.

Building upon your idea, perhaps a solar hot water collector plumbed into heat exchanger pipes installed in the bottom 1/3 of the propane tanks. I'll need to find out how much efficiency loss occurs in the heat transfer, and if the amount of heat generated would be sufficient.

Dumb as this sounds, I've also wondered if I can do some type of RF heat by installing components from microwave ovens inside the kiln... I would need a means to measure the heat that was being created inside the beams/slabs, and also a way to make sure that the RF waves were uniformly applied so that the drying would be consistent.

[Scott T Smith]

Don't know why I forgot to comment when I read this last night, but this sounds like a seriously cool day! I'd love to see some pics of a bench made from one of your slabs, and hope someone posts one!


I'm hoping that fellow creeker David Keller NC keeps us apprised of his progress in making his bench. 4 of the other slabs are due to be picked up in the next couple of weeks, and I'll ask the buyers to keep me updated as to their construction progress.

[Derek Gilmer]

The short answer is that I'm not sure. As I understand it, temperature does not transition well though a vacuum (think space), however many vacuum kilns use convection to convey the temperature up into the wood from heat exchangers installed in the lower half of the kiln. Thus, there is a missing link here.

Building upon your idea, perhaps a solar hot water collector plumbed into heat exchanger pipes installed in the bottom 1/3 of the propane tanks. I'll need to find out how much efficiency loss occurs in the heat transfer, and if the amount of heat generated would be sufficient.

Dumb as this sounds, I've also wondered if I can do some type of RF heat by installing components from microwave ovens inside the kiln... I would need a means to measure the heat that was being created inside the beams/slabs, and also a way to make sure that the RF waves were uniformly applied so that the drying would be consistent.

Another few thoughts that you might have already passed up. But what about a dehumidifier style kiln instead? That way the head gained from solar can be combined with DH drying. I suggest this only because I know very little of vacuum kilns. What kind of actual lack of pressure do they generate? If they are getting close to a true vacuum the propane tank may not be a good option. I'd hate to see something like this: http://www.youtube.com/watch?v=Zz95_VvTxZM happen to your kiln.

[James White]

Just buy one of these. How much could they possibly cost.:D

http://www.usedvacuumtrucks.com/

James

[Scott T Smith]

Another few thoughts that you might have already passed up. But what about a dehumidifier style kiln instead? That way the head gained from solar can be combined with DH drying. I suggest this only because I know very little of vacuum kilns. What kind of actual lack of pressure do they generate? If they are getting close to a true vacuum the propane tank may not be a good option. I'd hate to see something like this: http://www.youtube.com/watch?v=Zz95_VvTxZM happen to your kiln.

Derek, thanks for the suggestion. I'm actually in the kiln drying business, and I own and operate a Nyle DH kiln.

It would take about a year to dry a 4" thick oak slab in a dh kiln (w/o damaging the slab). Vacuum is the only practical option for kiln drying a thick oak slab.

[Adam Cormier]

Will be a nice bunch of workbenches when they get to that point!