How would you T&G a whack of 5” x 13” beams?

[scsmith42]

I'm milling out some pine 5x13's to use for retaining walls here on the farm.  In one area alone I need to make a 7' tall, 300' long wall so it will be a lot of beams.  I plan on having them pressure treated after drying them down below 25%.

My lengths are random, so some type of T&G will increase my yield of usable lumber since I won't have to start and stop each beam on a support post.

What I'm thinking is milling a 3/4" deep groove, with a 3/4" tall tongue, approximately 2" wide centered on the narrow edges of the beams.  

The tongues shouldn't be that difficult to cut. I can use a circular saw with a guide to make those cuts.

However, I'm drawing a blank with respect to a quick, easy way to cut the grooves.  Sure, I can use a router but it will be a lot of passes and time.  I can set them up in the Peterson and use it to cut a groove, but with a 1/4" blade kerf that will be a lot of passes end to end to cut a 2" wide groove.

Humping 5x13's up to 24' long across a dado blade in a tablesaw ain't what I'd consider a viable option....

One option may be to have a custom blade made for the Peterson that has a wider cut and use it solely for cutting the grooves.  That would probably cost upward of 1K though and that's a lot to spend on a one-time project. Also it will be time consuming to set each beam up on the Peterson, versus using some type of portable system.

Any thoughts from the FF Brain Trust?

Thx.

Scott

[Mossy Chariot]

Hey Scott,
My first thought would be to consider cutting "V" shaped tongues and grooves.  Still a lot of work but doable with a circular saw setup. 

[LeeB]

I think I would consider a floating tongue and groove both sides of the beam. That doesn't help you any with the grove but you could then use store bought treated 2x for the tounges. A 3/4" router but in two passes with a hand held router shouldn't take too long to do with one pass from each side.

[WDH]

Maybe you could convince Jake to do it on his 4-sided pinheiro planer, but it would probably take a custom knife to do it. 

[Don P]

Mafell makes a groove cutter, at their price point :
https://www.timberwolftools.com/mafell-nfu32-groove-cutter
I think I remember a Makita one but don't see it on a quick search

There was a skillsaw that ran a dado head years ago, used by California roof cutters and some of them modified regular worm drives to swing a dado head. Not overly safe which I think is why they are no longer around but one might pop up on one of the sale sites.

[bluthum]

Craftsman once sold a stacked dado head for a skill saw that worked pretty well but I haven't seen anything like that in a long while. I believe the cutters were 6" in diameter. 

[doc henderson]

if you cut grooves in both beam edges, and use a spline as described, it would save you a lot of wood on the face of the beam to build the wall.  A dado blade on a skillsaw sounds the best.  could be done in place on saw horses.  a second option is to use pins (dowel) and drill holes, but this will not allow as much for movement.  many out door walls made with railroad ties and such, drill through several layers and drive rebar into the hole.  there are also screws for cabin building and such.  a 5/16th of 3/8th head an come up to about 14 inches long.  be sure and include "deadman" or "sleepers" back up into the hill.  could even consider a shiplap for some strength and easier to do with a skillsaw, and mabe a combo of the above such as the timber screws

[doc henderson]

another consideration is weather proofing.  the pressure treating is good.  some will roll on tar and some sort of plastic or membrane on a moisture and soil contacting area.  I used something called dimple board on below grad concrete.  I now think they have it in places like lowes.  It creates a gap to allow water to run down to drain tiles so you do not build up hydraulic pressure behind the wall if rain water saturates the soil. drain tile, gravel with soil separator fabric, just like a basement.  will the wall be straight?  if so will need lots of support.  like building an above ground swimming pool 7 feet deep

[GAB]

Scott:
Less than 5 miles from me there is an individual who has a 5 head weinig(sp) machine that he uses to make all kinds of trim, flooring, molding etc for home builders.  I know he has the capability to make knives for whatever Mr. P.Q. Public may desire that his machine can handle.
I do not know how wide or how thick of a piece these machines can handle.
I do not know the shaft diameter of the side knives.
Top & bottom (as the piece goes through the machine) would be planer knives.
Hopefully this can help you.
GAB

[doc henderson]

If you do tongue and groove, I would put the tongue up so as to not retain water in the joint.  could even do a Z joint, like a 1/2 dovetail, and cinch up with screws from behind and pull things together, and there would not be a "trough" for the water to settle in.  same for the ship lap joint.

[Crusarius]

What about just making a line of posts and resting the timbers against the back side? do you need / want it to be flat?

Still need to do all the water stuff but would make it very easy to just drop timbers against the back side of the posts. Also make changing them as they rot easier.

only fancy thing you may need to do with this setup is a mortise and tenon for the end joints. But that is only if the cantilever is to great from the supports.

[Jim_Rogers]

 

 

Standard skil saw with several blades makes a wider cut.

Jim Rogers

[scsmith42]

if you cut grooves in both beam edges, and use a spline as described, it would save you a lot of wood on the face of the beam to build the wall.  A dado blade on a skillsaw sounds the best.  could be done in place on saw horses.  a second option is to use pins (dowel) and drill holes, but this will not allow as much for movement.  many out door walls made with railroad ties and such, drill through several layers and drive rebar into the hole.  there are also screws for cabin building and such.  a 5/16th of 3/8th head an come up to about 14 inches long.  be sure and include "deadman" or "sleepers" back up into the hill.  could even consider a shiplap for some strength and easier to do with a skillsaw, and mabe a combo of the above such as the timber screws

That's not a bad idea except for the fact that the bottom groove may retain water and rot out.

[barbender]

I think I saw in a Post and Beam book, a setup using a gas concrete saw with the abrasive blade replaced with a dado stack. Yee-haw!

[scsmith42]

Hey Scott,
My first thought would be to consider cutting "V" shaped tongues and grooves.  Still a lot of work but doable with a circular saw setup.

Not a bad idea.  
The reason that I'm thinking about a T&G is that I have a variety of log leangths to use (10' - 16').  My posts are currently installed on 10' centers, and if I do a T&G I can use random lengths and maintain acceptable wall integrity.  Otherwise I may have to cut the beams down to match the post spacing.

[scsmith42]

Maybe you could convince Jake to do it on his 4-sided pinheiro planer, but it would probably take a custom knife to do it.

I have a 50hp Oliver, and I'm not anxious to hump a 16' 5x13 through it!  

On second thought, it would be Jake's back taking that abuse - not mine.  Danny, what a great idea!  8)

[WDH]

Now you are getting the picture ;D. 

[Stephen1]

I think if I had post in the ground, I would dry stack with no grooves, they only allow  moisture to be trapped. I would use Log home Screws, they have tremendous sheer strength so they would hold . They also will allow the wall to shrink in height. The also will allow you to change out rotton beams in the future.
The only really good way is concrete pavers that are designed for walls. They last almost forever. 

[farmfromkansas]

I built a couple retaining walls from treated poles one time, just used a post hole digger and put the poles edge to edge standing up.  Worked well till the house burned down.   Another short retaining wall I did at the farm, used hedge posts vertical about 4' deep, and on the dirt side stacked bridge planks.  That worked well.  Also have used the concrete retaining wall blocks, which are great, have to be stacked on clean gravel, and backfilled with gravel, so the water can get out from behind the blocks.

[Stuart Caruk]

I would take a chunk of aluminum and make a sled to hold 2 or 3 routers. It would attach to my mill so after i made the can't I could use the powerfeed of the mill to push the sled and make the cuts needed.

[scsmith42]

Thanks all for the ideas - please keep them coming!

[Hilltop366]

I'm thinking the tung would want to be a bit tapered for easier starting and shorter than the grove depth to allow for inconsistencies. 

[longtime lurker]

Wouldn't be a problem to grind a set of knives down but me I'd use dowels just for simplicity... 3/4 hole drilled either side every couple feet, pump a bit of PVA into the holes as you erect and just clip it together like Lego. Either way machine first, pressure treat later.

[Brad_bb]

The machine that was designed to do this is Woodmizer's MP100 (which I have).  They build them in Poland and I think the original purpose was for making interlocking D logs or timbers.  Some molding knife profiles are available or custom ones can be made.  I only use mine for planing/jointing. I don't have any moulding knives.  

https://www.youtube.com/watch?v=hyNh39oUnvE

[WLC]

IF it were me I wouldn't even try to go the T&G way on a retaining wall.  Use a deadman as needed for vertical stability and use timberlok screws to screw one layer on top of another.  They make another type timber screw that has a flatter, wider heard than a timberlok, but I can't think of the name of it now.

[jimparamedic]

If the Peterson will cut angles why not just cut a V into the bottom and the reverse on the top. then they would interlock be self centering self draining.

[Don P]

Ahh, Jim's mention of the Peterson, not sure if the Peterson is the same as the Lucas arbor. Can you have a Craftsman molding head bushed and machined to mount on the swingblade? If so gang them all up on edge on a set of bunks, bar clamp in line and begin indexing over one by one and plowing grooves.

[btulloh]

That's a big project.  Maybe you could turn it over to the Army Corps of Engineers and let them deal with the details.   :D :D

I'll be looking forward to following your progress on this.  Very interesting.

[scsmith42]

Ahh, Jim's mention of the Peterson, not sure if the Peterson is the same as the Lucas arbor. Can you have a Craftsman molding head bushed and machined to mount on the swingblade? If so gang them all up on edge on a set of bunks, bar clamp in line and begin indexing over one by one and plowing grooves.

Don, that's an interesting idea.  I might be able to machine an adapter that lets me mount a mounding head spindle to the blade arbor.  That way I could use one of my existing mounding heads and be able to use the T&G blades on the moulder for smaller stock.

The primary drawback that I can see is that the RPM would be fairly low for the application.  The plus is that I'd have 29hp driving the spindle, so I should be able to cut the groove in a single pass.


All:  My objective is to be able to build a durable wall for the lowest cost.  That means using the random length 12' - 16' logs that I have in stock.  However, the problem then becomes the location of the support posts (which are already installed on 10' centers). 

When the wall was originally started I had a good source for used utility poles, which is what I was going to use for the horizontal members.  Unfortunately my source went away after I had installed the posts on 10' centers.  So I'm now looking at milling 5x12's for horizontal planks.

If I use a T&G joint, then at locations where an end seam falls in-between posts the 5x12's immediately above and below the seam will provide support.  With a v-groove or shiplap I lose some strength at these end seams and would need to use fasteners.

The timberloc screws are great (was planning to use them to attach the 5x12's to the posts), but 8" screws cost about .65 each when bought in 250 screw lots. The 10" screws for attaching the timbers to the post run around .78 each.

 I'm estimating that I will be using around 200 pieces of lumber and have 40 posts.  If each post requires 3 screws per plank, posts where 2 planks meet will require 6 screws at the connection.  Assuming every other layer has a seam on the post, then each post will require around 31 screws.  Times 40 posts that's 1,200 screws, or $936 for the 10" post screws alone.

If I have to use four more 8" timber lock screws at each seam of the lumber that falls in-between posts, then that adds another 800 screws / $520 to the project costs.

If I use T&G lumber, I won't need to use screws at the end seams because the intermediate joints are supported by the planks above and below.  This will save me $500.  Plus the wall will be stronger.

At least that's how I'm thinking right now.  I don't think that it would cost me $500 in labor to cut the T&G, and since I'm looking at milling some type of edge treatment the costs would be a wash anyway.

One drawback that I see to this approach is the labor costs of handling all of the planks.  Green they will weigh around 500 lbs each.  

I was planning to use Tom's Baker mill to mill them (allocating the center portion of the logs that I sourced for a clear 2x12 order).  Milling a T&G with the Peterson means that each log will have to be loaded twice onto the mill.  Once for milling the tongues and a second time for milling the grooves.  

I may be able to take spare blade and machine it for the moulder spindle so that the mounding head and blade were attached at the same time.  That would allow me to use the mounding head to mill the grooves, and then rotate the planks 180 degrees and use the blade to cut the tongues.

It just occurred to me that I could set up two profiles at the same time in the moulder head - one for T and the other for G.  To switch between them I'd only have to shift the carriage a few inches one way or the other. This would be faster than using the blade to cut the tongues.

As I'm mulling this over in my head, at the end of the day the labor savings may not be that great. However, If I install the planks square cut then I'm going to need to install intermediate screws, or the dowel's recommended by Longtime Lurker.  This in turn adds time and labor costs.

Lots to mull over.  Please keep the thoughts coming.

Thanks much.
Scott

[doc henderson]

If you did plain planks, you could make some intermediate joints and back it with thinner lumber say 1.5 inch and screw it from the back to other members as well on each side of a joint.  this could be in a line or random with shorter segments to span the height of a joint and onto the above and below plank.  if you add dimple board to the back, will not allow pressure to build behind the wall, otherwise in saturated soil it would be the same as building a dam.the screws above may need to be stainless, but not as long maybe 4 inches (cheaper).  i guess you will have to look at time vs money savings.  If it requires several passes at slow speed, may start to add up.  you are clearly in touch with cost of materials and labor.  If you had 5 teenage sons, would be helpful!   8)

[Don P]

Rebar is a cheap dowel. If you weld up a cup type driver on the end of a cut off machine chisel and chuck it up in a rented electric jackhammer you would need to prebore but it would sink them fast.

For the T&G, if you have a square edged knife in the molding head that is ~1/3 of the plank width it can machine the T and the G on the swingblade. I'm not sure how much side load the arbor can take as far as a head hanging out in space banging into knots. The Craftsman heads swing 1" wide cutters so there wouldn't be much outboard strain but it would take 4 passes to do the T for a 1" wide single pass G with that setup. Shoot me a pm if you want one to play with, I've got my Dad's and FIL's and haven't used either. If it works I'll set up the other for the Lucas here.

[scsmith42]

Rebar is a cheap dowel. If you weld up a cup type driver on the end of a cut off machine chisel and chuck it up in a rented electric jackhammer you would need to prebore but it would sink them fast.

For the T&G, if you have a square edged knife in the molding head that is ~1/3 of the plank width it can machine the T and the G on the swingblade. I'm not sure how much side load the arbor can take as far as a head hanging out in space banging into knots. The Craftsman heads swing 1" wide cutters so there wouldn't be much outboard strain but it would take 4 passes to do the T for a 1" wide single pass G with that setup. Shoot me a pm if you want one to play with, I've got my Dad's and FIL's and haven't used either. If it works I'll set up the other for the Lucas here.

Don, thanks for the offer as well as the idea about the rebar.  That might be the ticket to avoid T&G.  
I have a Hilti hammer drill that would make short work of driving them, and a pre-bore with a ships auger in a 3/4" drill wouldn't take much time.  
Hmm....

[longtime lurker]

Kinda rough but if your concern is time (money) over appearance... Gangnail plates would definitely work. And strong those things... they won't let go that's for sure.

Just whack a bit of brown (or green if your treating with CCA) paint on them after and they won't stand out so much.

[jcbrotz]

Do you have a Festool domino? They make outdoor dominos that would be easy and strong.

[Peter Drouin]

How about t&g just the ends, butt them together timber locks/ rebar thing. 
Brake the joints up.

[Crusarius]

What if you were to cut a rhombus shape instead? then they self stack and self lock. would only need some type of end joint if you wanted to. Probably not necessary.

May need something on back every so often to hold them together and keep from sliding off. but once you backfill behind it the grade will hold it in place.

The other nice thing about the rhombus is the flats between the beams would be angles so it would not create a pocket for water to sit in.

[scsmith42]

Do you have a Festool domino? They make outdoor dominos that would be easy and strong.

I have the older 500 series

[scsmith42]

How about t&g just the ends, butt them together timber locks/ rebar thing.
Brake the joints up.

I'm thinking that if I drive rebar within a foot or so of the ends then I won't need to do any type of millwork.

[Peter Drouin]

That will work too, Good luck.

[doc henderson]

If you have a ton to do, might consider a pneumatic driver.  when I did my pool, had to drive a bunch of rebar pins into holes, and welded a 3/4 " piece of pipe to an air hammer shank.  could drive rebar pins in all sorts of difficult places for a hammer.  I have seen pole pounders in the NT catalog.  might save some time.  sledge will work good too.

[Larry]

Retaining walls fail because the weight of rain water overcomes them.  In a toad strangler rain T&G will hold the water and your wall will fail.

I use #4 rebar pins that I gang cut with a chop saw.  The water can seep between the beams.  When the wall gets too high I use dead men.  I have used salvaged chain link fence with good results.

Full disclosure....I've never done a wall as high or as long as your contemplating.  That's a major project and I would get professional advice.

[scsmith42]

Scott:
Less than 5 miles from me there is an individual who has a 5 head weinig(sp) machine that he uses to make all kinds of trim, flooring, molding etc for home builders.  I know he has the capability to make knives for whatever Mr. P.Q. Public may desire that his machine can handle.
I do not know how wide or how thick of a piece these machines can handle.
I do not know the shaft diameter of the side knives.
Top & bottom (as the piece goes through the machine) would be planer knives.
Hopefully this can help you.
GAB

Gerald, I have a 6 head Wadkin moulder, and am familiar with moulder operation and limitations.  It won't handle a 5" x 12" beam.  
There are some special Moulder's designed for log cabins and timber frames that might be able to handle it, but they are uncommon and very expensive.

[LeeB]

Are you building against an existing bank or building up the elevation? I fully agree with the deadmen and if building up back fill as you go. For an existing bank you will still need to anchor you wall to the bank somehow. Like Larry mentioned, the water that gets trapped behind it is what will cause it to fail. Leave drain holes in your courses.
 

[GeneWengert-WoodDoc]

It is important to design any fastening sYstem to accommodate swelling and shrinkage.  Also, there is likely to be one major crack so you might consider a saw kerf in advance so at least the crack is in a location where you want it to be.

Specifically, the difference between wet and dry in a 10" diameter log is about 5%, which would be 1/2".  If you put up wet logs, then they will dry so there is a 1/2" gap between logs.  With warp, the gap can vary between zero to 1".  If you put up dry logs, then when they get wetted, they will try to swell, but the weight restraint by adjacent logs means they will warp.  If they are fully retrained, then the cells will collapse to accommodate the 1/2" swelling, and then when they dry, there will be a 1/2" gap.  Note that fasteners will not prevent shrinkage and swelling.

Even if the gap is smaller, there will be enough room for air and insects.  So, there are various gap fillers, called chinking.  In the older days, chinking looked like tarry rope.

So, we prefer a joint between logs that can move without developing a space crack.  Ship lap is a good option.  The "V" is not quite as good.  T&G is okay if the tongue is plenty long...appreciate that the tongue is also trying to hold the logs straight, so a skinny tongue will break off easily if a log wants to twist, crook or bend.

Have you considered a "D" shaped log?  It gives a smooth wall surface inside.  Or maybe slab each log heavy and then use the slabs as siding with sheathing underneath and even insulation.  The slab approach will look like a log wall, but is easier to fabricate and maintain.

[customsawyer]

When ever you want to do it let me know. I'll make sure I'm out of town or my planer is not working. :D

[scsmith42]

When ever you want to do it let me know. I'll make sure I'm out of town or my planer is not working. :D

Jake, if you're here helping me then that means that you're "out of town"!  Thanks much for hiding your offer to help in a riddle!