Fitting Tenons (long)

Re: Fitting Tenons (long)

Jack Guzman from Maine

>Hi Bob,

That job of cutting tenon cheeks to the shoulder line is done alot more efficiently with a rip cut back saw.Some people use a Japanese style saw or a frame saw.I suspect your rip saw isn't as sharp as it could be so you're actually making this alot harder on yourself.To do this you need a saw that will stay to a line.You could cut multiple crosscuts ,clean out the waste,and clean it up with a chisel.---Jack

Re: Fitting Tenons (long)

William Duffield, on the Cohansey

>It appears you have more than one problem. First, 1/2" long "tenons," especially in SPF, are not sound joinery practice. Cope and stick joinery may work in low end kitchen cabinet doors, with a glued-in-place plywood panels, and very precisely matched joints, but I would not recommend it in your application. For strength, you should be using tenons at least an inch long, and the "mortise" should be closed at the end. Considering the additional shrinkage expected in the construction grade lumber I am guessing you are using, you might consider draw bored pinned M&Ts for long term strength and stability. You should consider drilling and paring your mortises, or chopping them with a mortise chisel and mallet.

Second, you are not using the optimal tools for cutting the tenons. A pair of backsaws, one filed rip for the cheeks and one filed crosscut for the shoulders, will be a lot easier to control, especially if you can find them at only two bucks apiece. Look for backsaws that are quite a bit smaller than one from a miter box, because those are too heavy to control freehand for precise work. A miter box saw, in a miter box, would be an excellent choice for shoulder work, however. As far as optimum TPI and set for construction grade softwood, I'll let someone else offer some suggestions, as my backsaws are optimized for joinery in seasoned hardwoods, and their narrow set and small gullets would choke on the stock you are using.

You might also want to consider looking for a plough plane, or even a combination plane, like a #45, for cutting your grooves. It should go pretty quick in softwood 2x4s and 2x6s, even if you were cutting full length grooves into which you would insert panels for structural stiffness.

You An' Self Orta Go Into Th Writin' Bidness

Hank Knight in SC

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Re: Fitting Tenons (long)

Bob Hutchins in Central Texas

>Howdy Sir William, OTC!

You are quite right in that I'm not using the best tools for the job;however, I'm using the ones that I have. My tenons are 1" thick and 3-1/2" long on the ends of 2x6 construction grade lumber. They are encased in an open mortise formed by cutting 5-1/2" wide rabbets on the ends of 2x4's and facing them towards each other to form the opening. When glued and screwed, the joint should be strong enough for a shop stand.

I do have a very cheap tenon/back saw that I bought from Sears many moons ago to use in a homemade miter box. Think I'll give it a try in making the rip cuts to form the faces of the tenons and rabbets. Can't be any worse than what I did before. Only problem is the tenons and rabbet faces are deeper than the saw so I'll wind up having to finish them with the carpenters saw.

Thanks for the input.

BobH

Re: Fitting Tenons (long)

William Duffield, on the Cohansey

>Now, I understand what you are trying to do. Some of those Left Coast joints, like Mr. Krenov makes. Yes, that joint should be strong enough, and easier to execute than a traditional M&T. If you handsaw is well tuned and filed for a rip cut, you should be able to get a pretty close fit, with practice. If it is filed cross-cut, however, it will want to wander all over, and the cutting will be really slow going. If it is already sharp, and is already filed crosscut, it probably has too much set. Have you tried sawing the corners at 45�, and then finishing straight across? Also, you should expect to pare the cheeks of both the mortise and the tenons with a chisel for a final fit.

Hmmm... Maybe I should go out in the shop and try it with mine before I offer advise about how easy it should be :^) I'll let you know later whether I'm successful.

Re: Fitting Tenons (long)

Bob Hutchins in Central Texas

>Howdy William!

Yep, the saw is filed rip but needs sharpening -- another skill I need to acquire. I did the cutting at 45 degrees on each side then flat sawing, but the lack of sharpness did its work to cause the cuts to drift. The good news is that I kept the saw on the 'right' side of the cut so that paring and planing would improve the fit.

They aren't by any means perfect, but they are about as close as my meager skills will allow in soft wood. If all proceeds well with the remaining seven joints, I'll post pics.

Thanks again for your advice.

BobH

Re: Bob's Challenge !?! *PICS*

William Duffield, on the Cohansey

>Well, I decided to see if I could repeat your precision joinery results, so I went in search of some scrap framing lumber. The closest I could come was a well seasoned PTSYP 2x4, which has been up in the loft over the shop for a few years. OK, not a 2x6 joined to a 2x4, but close enough. Since squaring the ends was not part of the challenge, I used an original DeWalt RAS, almost as old as I am, to chop off a couple of boards for the exercise.

I found a bit of space at the shoulder vise, turned over the glass. and the challenge was on.

I knew I was going to have to do something about the bottom of the mortise, so I set my mortise gauge to fit my widest mortise chisel, about a half an inch, and my cutting gauge to the width of the 2x4, 3.500003 inches, precisely, and laid out the joint on the ends of two boards. Since I wasn't about to chop the bottom out of the mortise, I started with brace and 1/2" Irwin bit, and drilled through the bottom of the mortise, half way through from each edge. The closest saw I could find to yours was my D8 thumbhole rip. Since I sharpened it myself, it cuts OK, but really needs a much more careful sharpening job to perform at its best. There were only two shoulders to cut, so I figured it would be quicker to use the D8 than to go get a crosscut saw. By now, I was about ten minutes into the challenge. Things might have gone quicker to this point if I had had a clean bench, with room to use my bench hook, but I made do with what space I had. Sawing in about the same pattern as you described, I ripped four 3 1/2" x 3 1/2" cheek kerfs, and ended up with three scraps and some toxic sawdust on the floor. I was now a bit more than 15 minutes into the joint, but the real challenge still lay ahead. I cleaned up the bottom of the mortise with the mortise chisel and a mallet. I trimmed the mortise cheeks with a paring chisel, and then went to work on making the two pieces of wood "slide" together. For this, I used the paring chisel some more, including a bit of cursory work on the sides of the mortise, and then turned to a #9 Stanley block plane to pare the tenon cheeks, and the mallet, again. After about a half hour total, I had one joint that fit, kind of.

In conlusion, I offer the following observations: "Thank the Powers that Be for Gorilla Glue and drywall screws!" That is one ugly, humbling joint. There's room in there for lots of spiders to take up residence. Nope, if I were given a choice of tools to execute it, I sure wouldn't have picked the ones you had available. St. Roy could have done better wielding nothing but a rock.

It's pressure treated lumber, so I ain't gonna' burn the evidence, and the dump's not open until Wednesday. Does that make you feel any better, Bob?

So, anyone else up to Bob's Ugliest Joint Challenge?

Well, Sir William!

Bob Hutchins in Central Texas

>Can't match that! I've got pics of mine but don't know how to post them in a message like yours.

You made the challenge a lot more difficult by fitting the joint in a single piece of 2-by material. My mortise is made of two 2x4's with a 1/2" rabbet on the inside of each. The tenon is a 1" thick tenon formed by sawing off a quarter inch from each edge.

Re: Well, Sir William! Second Pic

Bob Hutchins in Central Texas

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Pics Previewed but Disappeared. Go Figure!

Bob Hutchins in Central Texas

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Another try at pics

Bob Hutchins in Central Texas

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Bob, here is your problem..

Dan Donaldson

>You mentioned that it previewed, but disappeared when you posted it. This is a problem, especially if you use Firefox. After you preview to see the picture, don't post it from there. Hit the back button on the browser to get back to the original page where you started the post and post from there rather than from the preview page and it will work. Sometimes when you post from the preview page, it does not properly transfer the picture url to the right box and it doesn't post.

Re: Well, Sir William!

William Duffield, on the Cohansey

>Aha! That's how you managed a one inch wide tenon, and didn't have to worry about drillin' and choppin' the bottom of the mortise. Still, I'll bet my joint's uglier than your joint (still waiting for your pics), but my drive-by gloat on the shiney brace, beat-up rescued mortise chisel, and kewl metalhead tools of debatable utility were worth it.

Thanks, Dan!

Bob Hutchins in Central Texas

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I Give Up! You WIn on the Gloat

Bob Hutchins in Central Texas

>Sir William, but here's my entry for the ugliest tenon joint.

And Here's the Parts 

Bob Hutchins in Central Texas

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Re: I Give Up! You WIn on the Gloat

Pam Niedermayer - Austin, TX

>Well, there's your problem, you're using rulers instead of taking direct measurements. You'd think that 1/2" + 1/2" would equal 1"; but in practice, it doesn't add up, due to the vagaries of wood, precision of sawing and chiselling, etc.

The other problem is that the 2 2x4's are wider than the bottom piece (leg?). This will never look right. Kind of like putting a stack of large hardback books on top of a couple of small paperbacks.

Pam

Re: I Give Up! You WIn on the Gloat

Bob Hutchins in Central Texas

>Howdy Pam!

It's just a DP table based on one in a ShopNotes (or Woodsmith) article. The legs are doubled 2x4's on all 4 corners with 2x6 bottom rails that will have a plywood bottom to contain sand to lower the tables center of gravity to accommodate the DP. It shore ain't gonna be fine furniture! Cutting the pieces by hand was more of a challenge and learning experience than an attempt to make "sumpin purdy".

Guess this means I'm gonna have to learn to sharpen saws, now.

BobH

Re: I Give Up! You WIn on the Gloat

Pam Niedermayer - Austin, TX

>Sure, I understood that. But if you're going to load this structure with sand, I think you want a sturdy structure. Maybe big old screws through the joints will do the job, three per joint? And it still won't ever look right. :)

Pam

Re: I Give Up! You WIn on the Gloat

William Duffield, on the Cohansey

>In my case, I didn't use rulers either. The dial indicator, feeler gauges and double square were just props for the photo, to add to the humor. What I did use was a RAS that I knew was square, since that wasn't really the issue. I could have used my miter box if getting the end of the board square were part of the "challenge".

Re: I Give Up! You WIn on the Gloat

William Duffield, on the Cohansey

>It's a bit hard to tell from the resolution of the photos, who "won", but I think both of our rip saws can be classified as "rough framing tools" at this point. I'm going to have to try resharpening mine, and taking some of the set out of it. It would be fine for framing lumber, but even my seasoned SYP didn't need nearly as much set as it has now.

I think you would get a bit more strength from your joint with a bit narrower tenon and a bit wider shoulders, say 3/8" instead of 1/4".