I'll be putting in a floor soon using 1 1/2 to 2" thick spruce or fir planks joined to each other. One option for this is to use tongue and groove 2x planking intended for siding and roof decking, however I would like to look into the possibility of using rough sawn boards, finishing the myself, and grooving them so that a free-spline arrangement can instead be used.
These planks will form a floor structure unsupported for a span of about 7 feet (that is, there are no floor joists)
What might be some good arrangements for cutting such a groove into the edge of a plank, perhaps 1/2 to 3/4" deep and 1/4" wide or so. Keep in mind speed and accuracy.
One arrangement I have considered is to stack blades in a circular saw, remove the guard, and either mount it horizontally to a special built table so that the planks can be fed into the blade, or else modify the base with a special fence so that it can be plowed down the length of the boards.
I do not want to use a router.
I've had pretty good luck using a molding head on an old radial arm saw. You can find radial arm saws very cheap on Craigslist. For some reason, nobody likes to use them anymore.
(https://forestryforum.com/gallery/albums/userpics/26833/Molding_Head.JPG)
(https://forestryforum.com/gallery/albums/userpics/26833/Fence.JPG)
(https://forestryforum.com/gallery/albums/userpics/26833/Board_Buddies.JPG)
(https://forestryforum.com/gallery/albums/userpics/26833/TG1.jpg)
(https://forestryforum.com/gallery/albums/userpics/26833/TG2.jpg)
You could use the groove cutter in both sides for a spline. However, if you have to cut both sides anyway, might as well go with tongue and groove.
You can get blades and molding heads here:
http://corobcutters.com/
Looking for something like this:
(https://forestryforum.com/gallery/albums/userpics/29312/IMG_0261.JPG)
Thanks for the suggestion. I've got access to such a saw, I believe.
Why not simply stack a few small blades (either 7 1/4" or the little ones for hand held battery circ saws) in the radial arm to use it for a groover?
However, part of the motivation for using a handheld circ saw to begin with is to have the option of using this saw as a beam groover as per Jim Rogers' suggestion on a number of other threads.
nice set up brian, cool pics too.
Stacking some blades on the radial arm saw would probably work too, but I've never tried it. There's certainly room for several on the arbor. However, I would use the smallest diameter blades you can find for the 5/8 inch arbor (probably about 5-1/2 inches). When you spin a larger diameter blade, especially a thick one, you'll put more strain on the motor (much like a dado blade). Smaller diameter blades are better as well as bigger motors with more hp. Likewise, I wouldn't expect a circular saw with stacked blades to cut as fast as a single, thin-kerf blade.
D L Bahler
Their are old rules of thumb passed down to me by my father. One related to this question is the tongue and groove or spline method says that the tongue should be 1/3 of the board thickness for the greatest strength. A 1/4" tongue is no where near the 1/3 thickness, at a 7' joist spacing I doubt that it would add little value to the strength of the floor. One method of making the joint for this operation would be to use dado blade in a good table saw. Their are portable tools for this purpose such as the Makita Grover 3803A. Yes I know it's costly but it can be used for a variety of other projects, like grooving logs.
Thanks Remle for the response,
I know of such rules of thumb, but keep in mind such rules are subjective. For example, they depend on, what are you splinning for? what tools do you have on hand? etc.
1 1/2 to 2" thick floor boards with a spline maybe 5/16 or 3/8" thick are very strong. yes 1/4" undershot it a little. We would not want to cut grooves 1/2" or 5/8" wide in this application.
Also the floor boards are wedged very tightly into place, which adds to the strength of the whole system.
Since these boards are quite wide and maybe 14 feet or more in length, I don't want to run them through a table saw.
If you have a router with an edge guide, you could use a ½ inch spiral up cut bit to cut mortice's into each plank, couple or three inches long.
Space them how you like (every 6 inches or 12 inches ?) along the length of the plank. A good bit would cut over 3 inches deep.
You could then cut loose tenons out of plywood or straight grain stock, 6 inches long.
Make your mortices slightly longer to make alignment easier.
Reference your cut from the bottom of the planks.
You could attach a square of plywood to the base of your router, and screw on a piece of 2" x 2" baton to make a simple edge guide.
If you have lots of money get a festool domino.
If your gonna span 7ft with floor boards I would go as thick as possible. :)
Quote from: D L Bahler on December 09, 2013, 12:16:01 PM
These planks will form a floor structure unsupported for a span of about 7 feet (that is, there are no floor joists)
Wow! Are you sure you want to span 7 feet with a single layer floor with only 1/4 inch splines?
Been done for hundreds of years. I've stood on floors like this that have been there for hundreds of years...
You would be surprised how well it works, and how stiff and strong these floors actually are.
(https://forestryforum.com/gallery/albums/userpics/29312/7790232984_34a2c67ed8_o5B15D.jpg)
This one's stood up just fine since it was built in 1698
Short of a shaper, the molding head on the radial arm saw has some advantages. First, it's much easier to run boards through laying flat on the RAS table then trying to run them up on edge against the fence on a table saw. The molding head cuts nicely and you can keep the knives sharp by running a sharpening stone over them. Routers are pretty slow and very loud. You just can't expect a tiny little router bit to cut through hundreds of board feet quickly. Besides, you'll get a more consistent cut along the entire board length with a molding head and table (with appropriate clamps and feather boards) then with a hand-held router and edge guide which is more sensitive to knots and imperfections along the edge of the rough cut boards.
I'm using the Corob "wedge shaped" tongue and groove molding knives. The tongues are about 3/8" wide which works great for my 1-1/2" thick boards. However, since the knives are only 1" wide, I have to make a separate pass on a saw to rip off the 1/2" excess on the tongue cut (that's why the groove is closer to the bottom in my photos above). The advantage of the "wedge" shape is that it really helps to mate the boards together during installation. It's much easier than trying to fit together square cut tongue and grooves or splines—especially for long floor boards. Here are the knife profiles I'm using:
(https://forestryforum.com/gallery/albums/userpics/26833/40_Tongue.gif)
(https://forestryforum.com/gallery/albums/userpics/26833/41_Groove.gif)
Why is the tongue a bit longer than the groove? Looks to be .3170 vs 5/16 (.3125) respectively.
I believe those are diagrams of the cutting heads, not the final product. This would mean the inverse is true, the groove is slightly deeper. That would make tight assembly easier
How would it work to simply use a dado blade in a radial arm saw so oriented? I would rather cut all of the plank joinery as grooves than have to perform 2 different operations.
I don't see why you couldn't. However, I haven't tried a dado for this purpose so I can't comment on how fast it would cut compared to the molding head. As I mentioned before, you would also want to use the smallest diameter blades you can find. I would definitely use a 6 inch diameter dado set rather than a 7 or 8 inch diameter set—especially because you have no need to cut the grooves very deep.
Process all your grooves, change the knives, then process all the tongues (actually, I have two molding heads so I don't even have to change the knives--just swap the head). I wouldn't really consider that an extra operation—you still have to process both sides of the board regardless. Are you planning to make your own splines too? If you are, I believe you'll be dealing with more cutting operations when you include the spline making as opposed to cutting the tongue and groove directly. You will also need to make sure the splines and grooves are properly sized to fit together correctly. I think the matched wedged tongue and groove set will fit together much easier. In contrast, you might have to ease the edges of the spline with a plane to help them fit together depending on how tight the joint is. You wouldn't want it too loose either.
One simple reason not to cut tongue and groove but to use a free spline is that I want to create suitable reproductions and replications of traditional methods, and I'll feel better about myself if I stick with the 'old' 'right' ways, even if alternatives are easier or superior.
Thanks for your help, by the way, you have given me some good ideas.
Ah...gotcha. Just make sure you use those authentic 17th century power tools when you cut those grooves... ;)
:D
Methods are nice, but not strictly necessary.
If you're interested in using a radial arm saw, it's imperative that you construct a proper, flat table for it and you take the time to properly setup, adjust, and tune the saw for safe operation. Radial arm saws fell out of favor because they gained a reputation for being "dangerous". However, this was really due to people not learning how to use them properly or setting them up correctly. They've also been pretty much displaced by the compound miter saws. However, the RAS is a more versatile machine that can also be used for ripping and moulding.
http://www.youtube.com/watch?v=QKSkZ1vAzNc
I highly recommend purchasing the book "Mastering the Radial Arm Saw" by Wally Kunkle. It's a must have book:
http://mrsawdust.com/
Also, check out the DeWalt Radial Arm Saw Discussion Forum (DeWalt was the originator of the radial arm saw and arguably made the best ones back in the 50's and 60's before Black and Decker bought and ruined them). These old DeWalt machines are awesome. You can still find and buy them for great prices. The RAS I used in the photo above is one of the crappy Black and Decker models, but I also have a nice vintage cast iron DeWalt model that is a precision machine.
Well guys, you still can buy the old Dewalt RAS, GU GE and GW if i remember well.
http://www.originalsaw.com/
They bought the molds from B&D i think.
On my shaper, i habe a kind of tongue and groove which does it all in one pass, you just flip the board, and you're sorted. I'll try to take pics.
I would not part with my RAS, and it is a Rockwell/Delta.
The ceiling / roof of my church, built in the late 1960's, is basically 4x6s with a double tounge and groove system spaning 12'. It can definitely be done, if it were me I would glue, titebond my preference, every inch of every surface connection so you are not only relying on the tounge and groove
Dave,
Thanks for the suggestion.
Yes gluing sounds like a good idea, but it won't work in the long run. These planks will be fairly wide and as the structures are designed they must be able to flex and be adjusted throughout the life of the structure. The wedging action of the tapered planks creates a great deal of friction between the planks which makes the whole connection exceedingly strong (the splines don't actually do as much work as you might think) and I need to be able to adjust that friction as the planks age. They will shrink and contract over a period of about 5 years before the adjustment will hold and be stable. This adjustment over a long period of time is not so good on glue joints. And glue can run into problems 50, 100, 200 years down the road (yes, that sounds like a silly concern but hey, I'm Swiss. We think houses should be built to last 500 years)
I should mention, It's also important to use the right kind of wood. Something like Oak will not work for this floor because it is too unstable and moves too much with the seasons. The ideal wood is spruce. White pine and fir will also work. Yellow pine is not a good idea. Hardwoods should be avoided.
I also vote for a spindle moulder or "shaper" as Americans call it. I have made several small batches of tapered loose tongue and groove boards on mine. Those that I have made have never been over 7 feet long so I did run the board edges over the jointer (a big jointer) first to get straight and square edges and then I used a simple S-shaped slotting head in the spindle moulder. It is a great advantage if the cutter does not touch the edge above or below the slot as that would bring it out of straight.
The cutters that are sold for making tongue and groove boards are intended to be used in four side moulders where they plane the entire edge at once. This is not possible using the short length of the spindle moulder fence as reference.
To me 7 feet distance between joists seems to pushing the limits for 2 inch floor boards. Are you sure that they weren't 2 1/2 inch thick?
If the old timers regularly did it then it is okay anyhow.
I should add another thing that I failed to mention,
Not only do I need to be able to cut grooves into heavy planks for floor construction, But I also need to be able to cut a double row of grooves down the length of 3 or 4" thick planks for my walls. The splines here aren't structural, they are there to stop drafts. It would also be nice to be able to use the same setup to cut spline grooves down the length of 4 or 5 inch thick, long timbers for log construction.
I like these solutions, but I still do kind of feel like to best fit all of these needs, some sort of handheld tool would be best. Right now I'm thinking along the lines of either a spiral upcut router (I may make some kind of custom router assembly with a special base) or a circular saw with the guard removed (yikes) and small blades stacked for grooving. Again with a custom base.
Also keep in mind, owing to the virtue of the construction methods I use (hey, I bi-n-e Schwiizeri Bueb...) the timber surfaces are all going to be pretty much perfect -or as close to it as is reasonable in something as imperfect (perfectly imperfect) as wood.
Then one of these would do all those jobs:
http://www.bamseprodukter.se/?page_id=14
A molding head suspended from a sled that rides back and forth on a sturdy frame. As the slab is stood on edge with the edge to be worked upwards and the lower edge standing on movable stops it is easy to set the two stops at it's ends at different heights. Therefore this setup can easily work straight profiled edges onto tapered slabs. I think Solosågen also sell a similar setup for their chain sawmills and I know that Woodmizer sell something fairly similar on the Scandinavian market as extra accessory for some models of their sawmills.
If you don't own a band sawmill or chain sawmill you could buy the molding head unit with motor and sled as an after market accessory and weld up a frame of your own. Some people do that in order to mechanize and speed up Scandinavian style log building where the logs essentially are 5 or 6 or 7 inches thick slabs. The standard knives sold for these setups are made for this log building style but as least Bamsefräsen uses an ordinary corrugated head so you could grind or order any knives you want for it.
Since I know didly squat about flooring I'll chime in. How about using oak dowel rods every 6 - 8"
https://www.youtube.com/watch?v=_3J5wkJFJzE
like this
That is a solution that works, but it's not suitable in this case do to the way the planks will be installed
No
Not like that at all.
I was thinking about this method:
http://www.youtube.com/watch?v=3J_PiyA9MTE
The cutter head is a standard currugated head that can be equipped with appropriate moulding knives to joint the edge of your planks and cut the grooves all at once. In this case it carries the knives for scandinavian log building but any profile knives can be used.
A similar (probably cheaper) machine from another maker:
http://www.youtube.com/watch?v=IN6AyVq7YO4
Sorry, TW, that response was to the suggestion about pegging the planks together. Go to 20 minute mark to see this
I'd love to have nice machines like that some time, but they are to expensive to justify right now. If I would have constant work year round building expensive projects, I would get good machines but as is, I'm looking for more or less low-tech solutions
What was the traditional method of cutting the grooves ?
Depends on the period.
Particularly early on, they might have used a chisel to chop them out -very time consuming.
Some time, someone got the bright idea to mount the chisel in a block and eventually you get a grooving plane. That was the primary method up to the middle of the 20th century. Now they use moulding machines. Always, the free spline was the method of choice. You do see some tongue and groove on some buildings -they seem to have tried this out around 1900- but most of the time the free spline is used even today.