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finishing massive redwood top on Kauai7/30
I am researching the the various aspects of a job that I haven't committed to yet. The client has asked me to take the lead on recieving a 21'x4" x 48-52" wide old growth redwood slab that will be the top to a dining room table( less a 4'+/- cut off for coffee table).
I think moving the slab is the least of your concerns. Becoming a student of mechanical advantage, leverage, and the inclined plane, is the easy part. The tenting, drying, and applying a finish you can stand behind, is the issue. I hope the customers timeline is many many months.
It looks like you have at least 7 problems identified. It already has a finish, and he's telling you to apply an epoxy on top of a finish? Major trouble. Tent it and dry it? How thick is it? How are you going to get the core of the slab up to temp? Plastic isn't much of an insulator and getting the slab inside plastic up to a controlled 135 degrees will take something special. If it's 12% all the way through, that's plenty dry for redwood. But if the surface is just 12%, you have trouble. It will take more than one Porter Cable sander to sand that many square feet. Especially if the abrasive clogs with his finish. Ever tried to mix up enough epoxy to cover over 80 sq ft? Epoxy is exothermic, it will really build the heat in a 5 gallon bucket! I'd rent a forklift and one of those clam clamps they use to handle granite slabs. Injuring someones back will cost you a lot more than the right equipment. Let me take that back, I wouldn't do the job, so wouldn't need the forklift! Sorry, but just had to add my concerns to more than your two issues. I would only bid it time, material, and expenses. No bid will cover all the headaches involved. Just think of the sawhorses you will need to build to hold up a ton!
It seems to me there are a few things going in your favor. Redwood is relatively stable and Hawaii has high humidity.
It also seems to me there are many more things going against you. At nearly 5' wide and only 4" thick even a stable material has a good chance of cupping. The existing finish has be either be removed or a compatible intermediary finish applied. How do you safely move this thing around. A forklift sounds like an absolute necessity.
If you are a small one-man or similar shop I would seriously consider passing on the project. If you know of any large high end production shops nearby passing the project to them of a small fee might be a very good idea. They would be more likely to have the staff and equipment to handle the project.
I'm crazy to even think of taking on this project. It is worth concidering the possibilities of accomplishing this in a safe and efficient manner. It will be a t&m job, i'm not doing it otherwise.
I like the wheel idea and would like feedback on engineering it so it doesn't buckle . I would glue up a 2x ring that is about 3 layers thick and 3.5" minemum width along the radial lenght , frame out a slot and fill frame to perimeter then glue and nail 1/2" ply to both sides.
My concern with the wheel concept is lateral stability.
When the table is in the vertical position the wheels will be stable so long as your wedges hold.
However when the table is horizontal 4" of wedged table end isn't much to keep the whole thing from shifting left/right and having the wheel collapse sideways. I'm not sure how you could assure that the wheels stay parallel to one another AND at 90° to the table surface.
Good luck !
To BH Davis:
I don't know about the others but I'd really like to see photos of this setup if you end up putting it together.
I'll post pictures of the wheels and maybe a short video of the process of flipping the top.
Kim, I'm a small shop operator too, and often get pretty large projects.
If the piece is going into a location which is under construction, working on it there may have some advantages, like using come- alongs to lift from the roof framing to turn it over in nylon slings for toeing cars.
As for getting rid of the old sealer and flattening a large top like this, I would use my Makita 1806 Powerplane to prepare the top. If you don't have one, just figure it into the job, and you'll be glad to have it forever after.
Redwood is awfully soft to use for a table top, but you can greatly improve that with a penetrating epoxy. Last Thanksgiving, I made a work island for our cabin using Eastern Redcedar, which is about the same density. I heated the top up by using a little space heater blowing under a tarp suspended over the top, then let the contraction of the cooling air inside the wood to draw the epoxy in deeper, because my shop was too cold for the epoxy to kick. You may not need to worry about this out there though.
In the end, my cedar top looked and felt as dense as cocobolo, and seems to be staying redder than the legs and drawer fronts, which normally fade to tobacco color after a bit of exposure. How long it will stay red,,,,,, only time will tell. But the one coat of wipe on poly that I use over it looks great, and far superior to many coat of most finishing products.
I got my penetrating epoxy from Jamestown Distributing, but you may be able to find it at a marine supply near you. It was made by Smith's, and while it is expensive, it certainly will be worth it for the improvement to the surface hardness, and easier finishing that follows.
You bet I would like to see a video of that first turnover. I'm really glad I'm not your helper when the turn over assignments get made! Make sure you have your insurance paid up in case someone gets injured!
In simple terms. Don't be intimidated by this project, you've got time, tackle 1 problem at a time.
If you have a workshop large enough, that's 1 problem down. Buy some 2 by 4. Make a bench if you need to that supports the piece so that you can work on it 1 side at a time. Put yoga mats down first to cushion the bench and protect the work piece. A bunch of guys can easily help you lift the piece from a fork lift truck truck to the table. Keep backs straight and use a Fork lift as much as you can. Once the piece is in place. You'll need to let it rest in its environment until it is stable. The wood will acclimatize at its own pace and you can't work on it at all until it has.
Hawaii is humid as you know so one option and I've seen this happen, is to believe it or not, find out the average relative humidity year round for the room the piece will live in once completed. You can set up a dehumidifier solution to match that humidity level in your workshop.
Once the piece rests at a stable moisture content and therefore is no longer moving. You are free to work on it.
If it isn't flat at that point, I'd go with the router sled set up and shave off as little as possible to create a perfectly flat and uniform surface on both sides.
As for a finish, I'd consider building up layers of polyurethane by spraying to build up the required sheen and protection level. I think there's too much surface area to attempt an epoxy finish on your own although I'm sure it's not impossible.
Repeat on the other side but you should expect this project to take months not weeks.
Hope that helps...
Sounds like a great project, and the innovations suggest say to me that this is something you will enjoy.
Yes, take off the old finish. Power plane sounds like the way to do it. I'd cut it to length (if I understand that shaves off 400# or so, with 20% of it gone) then replace the finish on the ends, or wax them.
Letting it stabilize is a bit tricky. There's a table on Woodweb for equalized MC at a given RH. All I can remember is 50% RH gives about 9.5% in soft maple, but it will be different for redwood. Take the RH in their dining room, several times on several days, and use that as your target.
I distrusted the cheepie Home Depot $10 humidity sensors until I got 3 of them and compared. They agreed within one percent, which I take as verification. What does $30 hurt for a meter combo you can trust?
I'd use both pin and pinless moisture meters. With the bucks involved just buying this wood, let alone shipping it and paying you T&M, go for the gold and do it right. Pinless will average the MC up to their rated depth, once adjusted for density (like knots & crotches). Get a good Delmhorst or some such— the $2-300 will be worth it, and you can sink pins to different depths to check core MC. Test them against each other of appropriately thick samples to make sure they agree and to get a feel for any quirks.
When you mix the penetrating epoxy, beware the exothermic. Mis in a big (read: huge) flat metal pan, for max. heat dissipation. You can set the pan in ice if heat is still a problem, or make smaller batches. Remember, penetrating epoxy sets s-l-o-w-l-y. Some brands say 14 days. If your batches are an hour or two apart the epoxy will never notice.
Jobs like this get me excited. They are scary if you think about solving everything all at once for the first time, but when you take them apart they are just a simple series of engineering issues, leading to amazing outcomes. Go from one intelligent decision to the next, use plenty of common sense and don't be afraid to come back and ask for opinions. You'll get plenty, and I'm sure you are well equipped to cherrypick the best of them.
Aloha fellow woodworkers,
The sled works great, wish I had got a few more router bits.I end up diamond honing cutter a few times during flattening of top side .
Got Epifanes' flat mat urethane coming from Oahu this week. Slapping on one or two coats when top is in place .
I am hoping client love this top so much that he will keep it. Waiting on base from Bali . I'm setting top on temp blocks for Thanksgiving .
Yes , this is all T&M.I wouldn't have it any other way.I hope to get the Gopro on time laps for the flipping of top tomorrow.
Footnotes to pictures: