Questions about milling Doug Fir CVG T&G Flooring

[Dave van Harn]

A friend is doing some remodeling in an old house and needs some 25 8' pieces of 3-1/2" Doug fir clear, vertical grain, tongue and groove flooring. I can get rough C-VG (clear, vertical grain) Douglas fir for a good price from a local wood vendor (Mount Storm Forest Products) , and bought one 8' piece for trial run. It is just under 4" wide and only 57/64 ' thick. I planed, ripped and jointed it, and it looks great. Light planing takes it to the 53/64" thickness I need,so no problem making the boards.

Before I cut the tongue and groove in my 8 footer, I did a practice run on a short piece of pine. My questions are about the tongue and groove profile. As you can see from the picture (click to view large image), the original T&G (top board) is very loose with a negative rake above the tongue, I am guessing to help avoid a gap. Since they didn't have the sophisticated machinery that we have now, even in home shops like mine, I assume that "production" flooring like this was designed to fit without a gap, and could not be made like a perfectly tight fitting tongues and grooves like modern mass-production flooring.

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The bottom board is the pine sample I just milled on the router table with a kitchen cabinet shaker-style tongue and groove bit set. I routed the tongue just a bit short to make sure there was no gap at top between the boards. I then moved the groove cutter a bit for a loose vertical fit, but I don't know if this was necessary. For my production run, with careful setup and judicious use of feather-boards on the router table, I think I can get a good gap-free top surface fit by having a tight vertical fit of the tongue and groove. I plan to leave a bit of a gap at the tip of the tongue, unlike on kitchen-style cabinets. If there are any minimal surface irregularities after laying the floor, I have been told that is is common to lightly sand this type of flooring before finishing.

I am aware that vertical grain expands much less across the board than flat grain, and the boards that I will be using are true vertical grain boards. Do I need to worry about expansion? Does the negative rake with the small contact line and loose fit of the original tongue and groove accommodate expansion?

(I'm more of an "Artsy/Craftsy" woodworker, but worked for 5 years at a Woodcraft store and have been exposed to most types of working and have a pretty well-equipped shop. One thing that I did learn from my pro customers at Woodcraft is that there are often important subtleties to woodworking, and that older ways of doing some things often require more knowledge and skill than with modern, easy-to-install home improvement things.)

Dave van Harn
Sebastopol, CA
www.xulonn.com (http://www.xulonn.com)

[David Kumm]

What is the moisture content. I would guess it is shrinkage that is more likely as the DF may be more like 15% rather than 10. If so even VG will gap a little. Dave

[Dave van Harn]

The doug fir has been stored inside all summer at Mt. Storm's warehouse, and is very light in weight.

Don't have a moisture meter, but may borrow one.

Dave

[Peter Quinn]

The original flooring is correctly made, yours may give you trouble on install. The original tongue is not "loose", it is tight where it counts. This stuff is meant to be nailed down, so the bottom of the tongue holds the groove of the next board to the floor. The top of the tongue doesn't touch anything and need not be dead tight. Typically the tongues are under sized by some margin, at least .010"-.015" or perhaps more versus the groove to make installation easier. Floor boards are not flattened, the come in long lengths, and it can be a bear to bang them together if they are too tight. The rest of the geometry on the edge is important too. The back bevel on one side gives you a nail slot on the tongue and allows the faces to join tightly despite sub floor surface irregularities and twists in the floor boards, the gap at the bottom insures you don't get bound there by debris or changes in the sub floor elevation. I don't think wood movement is accommodated by rake angle.

You are incorrect in assuming old floors were not accurately made. As early as the mid 1800's strip flooring was being made by steam powered through molders whose tolerances are similar to what may be achieved today. Perhaps the boards were milled more green as large electric kilns were not prevalent to my knowledge, and thus shrinkage might have been an issue, but the molding was probably better than what you can hope to achieve with a router table.

You may have trouble with DF as it loves to tear out in long ribbony shards and can be difficult to shape. We don't use it much but have had to climb cut it on occasion. This is not a problem on a shaper with feeder, its not safe on a router table freehand.

[Dave van Harn]

BTW, I used to refer Woodcraft customers to Sawmillcreek for questions I couldn't answer, and still refer people to this amazing place.

Thanks, Peter. I'm surprised you didn't give me credit for being wary and thinking about possible issues.

I am not worried about handling 8 footers on my cast iron router table that is a wing on my table saw. I use feather-boards plus infeed and outfeed support stands whenever it is appropriate. I am, however, wise enough to not think of doing climb cuts on long boards on my rig. Even when I take light climb cuts on much smaller pieces, it scares the hell out of me.

You confirmed that I had guessed correctly about the tongue being purposely loose at the tip and top, and the bottom holding down the groove of the next board. I also thought that the the rounded tongue might be to allow the next board to slip into place more evenly - so that bottom of the the groove of the next board would be pushed under the tongue instead of mashing into it in case of warp or other misalignment. I hadn't thought about the bottom gap as a place for debris or wrinkled vapor barrier to collect.

I had searched extensively when I worked for Woodcraft, and none of their router bit vendors (the Wood River house brand, CMT, Freud or Whiteside) manufactured a true flooring R&G bit. However,after searching the web some more this evening, I found that Rockler and Amana do indeed make flooring T&G bits. Here's the a pic of the Amana #55456, which I can get for $83 on-line from Dynamite Tool Company in New York that I would have to add to the cost of the job.
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I will also test the batch of Doug Fir to see if it will work with a normal cut rather than a climb cut. I have seen that long feathery tear-out/grain separation on fir 2x4's in the past, but didn't think about as being an issue for this project. ( That was an invaluable tip - thanks Peter.) If I can't do it on my router, I will have to see if one of my fellow local woodworkers has a shaper that I can use - again, more cost for the client.

Dave

p.s.Even though I have worked as a technical salesman for super precision bearing companies and machine shops, I wasn't aware that such precision in woodworking machines was found in mid-19th century equipment. My apologies for insulting our woodworking forebears! :o

[Peter Quinn]

Hi Dave, I give you lots of credit for taking the initiative to make your own flooring. My only hope in the comments I made was that you might avoid one of those "why isn't this working" moments of which I have had so many! I have made long moldings on a router table at home that lives in the TS out board table. I made two torsion boxes 12"X 8' which rest on the saws rails and clamp to the table, they are supported at the ends by roller feed stands with the rollers removed. It let's me focus on feediing and not worry about stock support. I used to use just a couple of quick plywood extension tables which worked well too. The Amana bits look just like a miniature version of the cutters we use at work. I work for a millwork shop with a heavy emphasis on custom flooring. We have made doors with DF and iit doesn't shape well. We have bought pre made DF flooring and re milled the tongues and grooves for clients, that seemed to go fine. If cost is an issue on 25 8' pieces you might be able to use the router freehand and climb it that way with somemsort of jig or clamping table if the cutter set has a bearing. Or possibly a brass bushing depending on the radius of the cutters.Good luck with thisnand work safe.

[Richard Wolf]

I am doing a large railing job with vertical grain Doug Fir now, it is almost impossible to run it through a shaper with a normal cut without stripping grain off. Climb cutting with a power feed seems to be the only option. Of course I have a large number of fittings to be made, which must be made by hand and can't be climb cut. My only solution seems to be very light cuts and make extra parts so bad ones can be discarded.

[Dave van Harn]

Great discussion and excellent advice.

I have e-mailed my friend a summary of this discussion to see how he wants to proceed. I just want to avoid problems, not lose money, and make a friend happy. He is an experienced precision CNC machinist who manages a good-sized shop, and will understand the geometry issues.

Dave van Harn
Wood Artisan
Sebastopol, CA
www.xulonn.com

[Dave van Harn]

A pic of the end of the test board with tear-out after a pass over a Byrd head shear-cutting jointer. I'm beginning to regret getting into this. I should stick with what I normally do - woodturning and box-making!!

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[Peter Quinn]

Well, if the tear out is only on the ends you can cut those off if your material is a bit long. If you have 8' boards to make an 8' room, that's a problem.

[rob durfos]

I have had pretty good luck with cvgdf in all mill work applications . I think it has to do with the way the wood is dried, pitch set, and conditioned. I get tear outs in pitch pockets but expect a run of flooring to go pretty smoothly. If you have some epoxy on hand , a little dab here and there will work well as tear out preventative. It maybe that the wood you possess may indeed be problematic in and of itself. Look up your friend with the shaper ! Good luck-