Layout M/T joints so they fit? I am an idiot

[swmn]

I built a table for my belt/ disk sander out of shop scrap.  I sliced up a 2x10 or two to make a laminated top and then 4x4 posts and stretchers.

I was using square rule to the 3x3 post inside the nominal 4x4 that was really +/- 3 3/8 square.

So I used 1 inch tenons and cut my mortises 1 inch wide.  None of the joints went home on the first try, I ended up having to pare the pencil lines off my tenons since that was a lot easier than shaving the pencil lines off all the mortises.

I also screwed up my drawbore layout on the tenons, but I think I understand why.  And I made the mortises too big for the pair of 4x6 stretchers I picked out of the scrap bin.  The point of this project was to learn from the inevitable mistakes and have a sturdy table for the sander.  

Overall I think the table is plenty strong enough for the sander, and I can fit a bunch of weight in the low shelf if it vibrates too much.  I need to think up something else small to have another go at before I spend big dollars on a building.  Maybe a dog house.

For M/T layout should I have been laying out my mortises maybe 1 1/8" wide, or laid out my tenons 7/8" wide?  

Thanks


 

[btulloh]

My experience is from the furniture side of things, but for either furniture M&T or timber framing, it's better to need a bit paring than have a loose joint.  Experience pays and after doing a lot of M&T, I get a lot closer to cutting them to fit right off the bat, but I still expect to pare a little bit.

Depending on how you laid them out, usually you would cut the line on one and leave the line on the other.  It all comes down to how they're laid out to begin with. 

Like I said, I'm a furniture guy, so some of the TF gurus will have some better input on the TF aspect.

That's a sturdy router table you made.  Good way to warm up for your timber framing.

[Ljohnsaw]

Maybe not right but here is what I do.  I cut all the mortises first.  I lay out and use a boring machine to remove most of the material and then chisels for the rest.  I have a corner chisel with works pretty well.  I make the reference side of the mortise plumb (small square) all the way down.  Then I use my 2" slick as  go-nogo gauge and pare down the other side.

Once they are all done, I cut one tenon using a caliper gauge set to the slick's width plus a little margin.  Again, make the reference side square and and parallel to the reference face.  Using the caliper, get it down to the right thickness.  Test fit in one mortice, paring down for a not-quite pound fit.

Using this tenon as a gauge block, go back and true up all the other mortises (or is it mortisi?).

Finally, make up all the other tenons.

For your next project, how about a couple Mare & Colt saw benches?  I've got the mares done, just need to finish up my colts.  I used 6x6 fir.  I'll track down my Sketchup file and post that later if you want it.

Rooster's Mare & Colt Timber Frame Sawhorse System

[swmn]

it's better to need a bit paring than have a loose joint... 

Depending on how you laid them out, usually you would cut the line on one and leave the line on the other.  It all comes down to how they're laid out to begin with.

I agree I would rather have to pare a little than have a loose joint.  
It seems like I laid them out "wrong" since I am getting better at cutting "to" my line with a handsaw.  I guess I could maybe eat the line with the saw and cut to the inside edge of the pencil line.  
Given I can barely lace up my own boots I think I would rather stay in the habit of cutting to the line all the time and scoot one of the pencil marks over a smidge.

[btulloh]

I use a marking knife to layout joinery. More precise. Then saw as close to the line as I can. Then place the chisel in the knife line to pare. That works best on mortises and tenon shoulders. Good marking leads to good joints. 

A lot of this has evolved over time as I got more experience. 

You can also deepen a knife mark and then cut a v on the waste side with the marking knife. This little groove will register a back saw precisely. Then all you have do is saw straight. Leaves a nice clean shoulder cut too. 

Once again, I'm coming from the furniture angle and TF has some different techniques. 

[swmn]

I have reviewed Will Beemer's method again in his _Learn to Timberframe_ book.

For my next practice project I am going to have to make a tenon checker, a board with a hole in it the same size as the mortises.

I agree the way furniture makers do it, essentially scribe rule for the other half of the M/T joint they are making is effective, but I want to figure out to do it without having to man handle 10 foot 8x8s over and over.   

So i will make a tenon checker.  I think I am going to make a scale model Sobon shed next, like doghouse sized with nominal 2x2s and half inch mortises and etc.  I'll have to modify one of my inexpensive bench chisels to make a scale model of a framing slick, but that will be fun.

Thanks for the ideas.

[btulloh]

That all sounds good, swmn.  A tenon checker is useful in both worlds.  Manhandling a beam is not useful in any world, or at least any of my world.  I think by the time you've finished the scale model you'll have the whole process worked out.  I know with furniture, it's all about knowing how to accommodate the inconsistencies of working with wood and how to please the eye as well as making sound joints.  It's just done to a different scale with TF, and knowing the allowable tolerances.

Keep us posted on your progress. Both the scale model and the real thing will be interesting to watch.

You might want to check out ljohnsaw's thread on building his timber frame.  It starts with his drawings, then an awesome scale model, and now he's working on the real thing.  It's interesting, educational, and entertaining.  Sounds to me like he's on the same path as you, just a little further along.

ljohnsaw's timber frame

[Ljohnsaw]

It starts with his drawings, then an awesome scale model, and now he's working on the real thing.

Thanks for the complement.  However, my scale model is not a timber frame - that is, no joints were cut.  Just glued up and pin nailed.  It was just a solution to cabin fever - unable to work due to snow for 6 months!  It also helps people that are plan-challenged - unable to read plans. :D

If you really want to start at the beginning, here is the design process I went though with the help of many on the forum. Messing with Sketchup - my cabin ideas

[Heartwood]

swmn:
I suggest it's just a matter of practice to know how much to pare. People just starting out tend to make tenons too fat and mortises too narrow, being conservative. The goal is to leave half the pencil lines on the tenons and mortises, but it also depends on your layout tool and how sharp your pencil is. Note that with the Borneman layout template that Jim sells the machinist has accounted for the pencil thickness, so if you hold the tongue of the framing square up against the 1.5" slot on the template you'll see a slight difference (the pencil lead thickness). You could make your tenon tester slightly narrower (1/32") to achieve the same thing. Use your framing square or chisel as a mortise tester (assuming it's the right dimension and not tapered). If you are using your framing square width for layout, or your combination square set to exactly the tenon thickness, then when you draw a pencil line and leave it when you cut the result will be too thick.
Practice. Once you get the hang of it you'll rarely have to pre-fit square rule joints before raising day.

[btulloh]

Personal preference, but if I'm not using a knife, I use mechanical pencils for layout work so my lines are consistent width.  I keep both the thick and thin versions around.  The thicker lead is helpful if you're on a rougher grain that wants to break your lead.  Some people like to Rapidograph pens so they get a dark ink line.  Works good, but no erasing once you make the line.  Easy to see though and consistent width.

Just throwing it out there  . . . 

[swmn]

Appreciate the ongoing input.  I think the main thing, at least for me, is to keep practicing until I have a method that works.

I did crack the Sobon book last night, he uses the framing square down in the mortise, and then holds the framing square up against the tenon.  He wants the tenon cheeks flush with the square and the mortise comfortable able to take the square.  I am not that good.

I got a bunch of 2x2 and furring strip last night, and made a modeler's sized slick out of a 3/4 chisel.  I'll let the wood dry in my shop a week or two while I am looking for a 7/16 mortising chisel.

Thanks again.

[Jim_Rogers]

I've got a 3/8" chisel on our for sale list. Let me know if you want a shipping quote.

Jim Rogers

[Don P]

I drag the framing square through the mortise and then use it to check the tenon. I paste wax the tenon and then try it. If it doesn't fit look for the burnished spots on the tenon. It doesn't offend me to sneak up on the fit. I've also seen some pretty sloppy old work that held up quite well.

[swmn]

Well I haven't quit.  I am "essential" so working lots.  One of my colleagues got out of quarantine yesterday, so only and eight hour day for me today after a week of twelves to sixteens and a weekend of call.

I brought an 8x8 in out of the cold.  I found my square faces and got that marked up, and then penciled on the line for a square end and managed to saw to the line all the way around.  That took some practice and this one is going in the wood stove too, so there will be no "proof" except I can do it now on the next ones.

Next up I laid out a tenon on my square end.  After I had the shoulder crosscut, it took me 18 minutes to chisel down close to the line and another about ten to finish it up real nice with my slick- only one face of the tenon done.  27:54 total according to my stopwatch.  Not planning to quit my day job, but I got pencil marks all the places there is supposed to be pencil marks.

Tomorrow is looking kind of brutal, but next time I get out to the shop I have 4" to take off the other side of the tenon, so I end up with a 2" thick tenon sticking out the end of my 8x8.   My plan is to try a rip saw on the first two inches and slick to that line, then mark off the last two inches that need to come off and do that with the chisel for a second chisel attempt again instead of a rip saw again.  I'll time all three before I lay out the fourth.

The 8x8 I am working is Alaska grown boxed heart , so either white or black spruce, seems like it will probably come in +/- 20%MC.  I will split open one of my offcuts in a few days after it is thoroughly thawed out, but I am pretty confident it will meter 18-24%.

1. My slick is 27 1/8 inches total over all length.  I know it could be sharper, but it really does feel a couple inches shorter than I want.  Is 29 inches a pretty common length ( I can buy clothes that fit good off the rack, 5' 10", ~180 #) or should I get it sharp enough I am sure that isn't holding me back before I find someone with a lathe to make a handle a bit longer?

2. Are you guys cutting frames in oak insane or masochistic?  This is a pain in the neck.

3. I left the line on the tenon planning to take the line on the mortise.  I guess we'll see how it goes, but I don't think  I am sophisticated enough to take half the line on both parts of the joint.

4. My 28 oz mallet feels like a tack hammer, my Barr 1.5" chisel is plenty sharp.  Would going up to a three pound mallet be reasonable?

5. My thinking is I can work an 8 hour day at my day job and average 1 joint per weeknight on a frame cut.  8 hours of paying work, plus one mortise and one corresponding tenon after work on weeknights.  Does this seem reasonable, cut a 90 joint building in about three or four months of weeknights with Saturdays for squaring timbers and doing layout?



 


 

[Hilltop366]

Dry spruce is hard cutting.

I was cutting some dead standing space with my DIY 16hp chainsaw mill when a old retired sawyer stopped to check it out, he looked it over and made the comment "huh, if it will cut that nasty old dry spruce it will cut anything" I was a bit proud of my creation that day.

[swmn]

I got some more shop time today.  I am moving a LOT of my customers to phone first and maybe go on site later if something breaks.

First I got playing with my framing square.  For me to use the two inch blade of my framing square to lay out mortises, I got to take the line when I lay out tenons, so I went back and slicked the line off the tenon face I did last night.  

Then I took two inches off the other side of the timber, creating a 4" tenon even though I want to finish with a two inch tenon.  For this one I used a five point ripsaw (golden age Disston D7, as sharp as I can make it) and cut right to taking the line off.  Total time was 11 minutes 6 seconds, including paring with my slick, so "a lot" faster with the tools I currently have.  The freshly exposed face of my offcut pinned 21% MC on my firewood meter.

But there are some issues here.  One, it is pretty clear my mallet weight when chiseling down to the line is too light.  I need a heavier mallet.  My saw is sharper than my mallet is heavy.  Also, my 8x8 timber is only about 45 inches long, and I had to rotate it twice.  After I had the tenon shoulder crosscut I rotated the 8x8 90 degrees for the first tenon face cut, and then another 180 degrees to finish the rip cut.  It would take a lot of extra time (or foolishness) to do the same with a longer 8x8.  Chiseling might also go faster, a lot faster with a 2" framing chisel, mine is still at the blacksmiths getting shaped.  He has it annealed but needs to get it squared up while it is soft before he hardens and tempers it.

I do notice the sore muscle I have from the rip cut is a different one from the one that got sore from chiseling last night.  For now I am thinking having both skills available is a good idea, different situations sometimes call for different solutions to the 'same' problem.

While I am waiting on my 2" chisel and building a 3# mallet I will next try rip cutting a tenon face without rotating the timber, that is make the crosscut of the tenon shoulder in the face of the timber pointing up, and then make the rip cuts from the sides without rotating the timber.  

I did also sharpen my slick, I took it up to 1200 grit on stones with a continuous burr to finish, I am a little scared of it now.