How to pare tenons plumb and square

[tibi]

Hello,

I have been working on my first workbench and I want to make it look good as I will have to look at it for many years to come.
I have planed all the wood for the base almost to the finished width and thickness. Now I plane boards to the finished thickness with my hand planes, then cut joinery (mortices and tenons), and finally glue boards together to form a component of the workbench base.

I have started with the smallest stretchers. A finished component is here:

I have found out that I have a problem to pare tenons square and plumb to the marked lines. In the pictures below, the shoulder is square and the tenon is off.

After further investigation, I think that the biggest problem is in my chisels. This problem is only exceeded by the inexperience of the chisel operator. I have been flattening this 38 mm wide chisel on the 240 grit diamond stone for 10 minutes, but it seems that it would take hours to get it flat. Other chisels are either bellied or are hollow in the middle, but have a belly just next to the edge, which makes the edge low. The tenons are 50 mm deep, and If I want to use a square block as a reference to cut plumb and square, then I would need at least 80 mm of my chisel to be perfectly flat. The chisel is at least 0,1 mm of being flat. I think I am not yet able to pare flat and square without any reference block.

Is there a better and faster way how to get the chisel flat than just using the diamond stone or should I just buy better chisels because these are way off?
Do you know some good videos on how to pare the tenons square and plumb so that I do not ruin my workbench? As you can see there would be a big unsightly gap on the shoulder if I left it as it is. I did not cut any mortices yet, so I can still remove materials from the tenons to repair them without making them too small. Also, you can see that the shoulder line (horizontal) is not uniform, but wavy.

Thank you.

 

[Jameshow]

How about 50mm chisel?

Cheers James

 

[thetyreman]

I would look at how you are marking out the tenon, there should a clear visible line which is your guide, for that I like using a cutting gauge, the type with an oval shaped blade which creates a very clean line and is extremely accurate, I also like to use a pairing chisel for removing the waste followed by a router plane for the very final surface to make sure it's dead parallel to the face, I don't know if any of that helps but good luck, that bench looks like it'll be very sturdy and built to last.

 

[Jacob]

Flat chisels not likely to make any difference. It's a popular delusion.
I'd cut the mortice first and then see how the tenon fits. Pare off wood where it's a tight fit - from the tenon, or the mortice, or the shoulders, as necessary.
No coincidence but a long paring chisel could help, say 25mm wide. The length gives you more control over the cut and being not too wide makes it easier, though not essential - any old chisels will do, not too wide.
You are working to a slightly peculiar design - are you following all the basic rues about face and edge marks, gauging from face and edge etc?

 

[tibi]

How about 50mm chisel?

Cheers James

The board is 40 mm thick, so I have only 2 mm missing. But I am able to buy a 50 mm chisel, if it would make a significant difference.

 

[Jacob]

.... But I am able to buy a 50 mm chisel, if it would make a significant difference.

No don't do it. If it's difficult go narrower not wider.
Aim at fitting tenon to mortice rather than getting one perfect then the other.

 

[tibi]

I would look at how you are marking out the tenon, there should a clear visible line which is your guide, for that I like using a cutting gauge, the type with an oval shaped blade which creates a very clean line and is extremely accurate, I also like to use a pairing chisel for removing the waste followed by a router plane for the very final surface to make sure it's dead parallel to the face, I don't know if any of that helps but good luck, that bench looks like it'll be very sturdy and built to last.

Thank you. I am using the wheel marking gauge. But I have a homemade cutting gauge as well. I need to go 40 mm down on one side and 50 mm on the other and I am not sure if my Veritas router plane can go that deep. I must try it out.

 

[Ttrees]

I find this is an opportunity where a fancy flush cutting marking gauge can be utilized,
a beam and a slip of timber is also good for longer tenons.
A plate of aluminium I find handy as a sort of winding stick, and also for finding high spots.
I suppose one made up from preferably a slip of uber dense tropical timber might be worth trying.
I use graphite so I can make it easy to see.
Might be a bit of faff for some, but could save your bacon on the other hand.

I can't say if you need better chisels or not, I use these cheapish flat ones for paring.
Flat backed/faced chisels being more prone to diving into the wood, so something to consider if looking to spend.
David has a good video about that.

I don't like paring assists, or at least haven't used one yet to good effect, the results I've gotten being an undercut.
Maybe I might like them if I had chisels like that, maybe someday for kumiko jigs, if I can get some cheapies.
Not that you mentioned anything about paring assists, just noting that flat chisels are more prone to undercut.

 

[Jacob]

Thank you. I am using the wheel marking gauge. But I have a homemade cutting gauge as well. I need to go 40 mm down on one side and 50 mm on the other and I am not sure if my Veritas router plane can go that deep. I must try it out.

You don't need a router plane for the mortice or the tenon. What are you doing with it?
Mortice - chisel, ideally a mortice chisel same width as mortice (up to 5/8" ish)
Tenon - sawn from all directions, with a 'tenon' saw - another coincidence!.

 

[tibi]

No don't do it. If it's difficult go narrower not wider.
Aim at fitting tenon to mortice rather than getting one perfect then the other.

Thank you, Jacob,

I have started with the smallest components (short stretchers), then I will make long stretchers and then I will make legs, where the mortices will be. I need to chop only two mortices per leg. I can make them slightly smaller and then adjust the tenons to fit in. But I need to have a perfectly square and plumb shoulder line so that it matches the leg where the mortice will be. Or I need at least to have it on the outer visible side.

 

[tibi]

You don't need a router plane for the mortice or the tenon. What are you doing with it?
Mortice - chisel, ideally a mortice chisel same width as mortice (up to 5/8" ish)
Tenon - sawn from all directions.

When I made this tenon (actually it does not look like a real tenon, it is just an L-shaped offcut) I have sawn across the grain and split with the chisel along the grain. My problem is that I am afraid to go past the line with the saw, so I saw away from the line 1 or 2 mm and then pare with the chisel to the line. When paring, always one area is lower than the rest and I need to adjust the whole surface to the lowest spot. When I do this, I inadvertantly create a new low spot and I am chasing my tail. And I do not want to make the tenon much narrower or longer during paring.

 

[Ttrees]

Do the mortises first, tenons can move after sawing likely a whole lot more than the other way round.
Easy to see if you ever cut a double tenon and the saw kerf closes up!

 

[Jacob]

Thank you, Jacob,

I have started with the smallest components (short stretchers), then I will make long stretchers and then I will make legs, where the mortices will be. I need to chop only two mortices per leg. I can make them slightly smaller and then adjust the tenons to fit in. But I need to have a perfectly square and plumb shoulder line so that it matches the leg where the mortice will be. Or I need at least to have it on the outer visible side.

You need to mark both mortice and tenon with exactly the same gauges so the marks match exactly. Then cut mortice right up to the line - erring on the side of going too far (too wide is better than too narrow), then cut the tenon exactly up to the line, also erring on the side of going too far - (too narrow is better than too wide).
Router plane is a specialised and rarely used tool which you probably don't need. I'd keep it in the box!

 

[thetyreman]

the router plane is ONLY for the final pass on the tenon, it creates a level of precision not usually achieved with just a chisel, it's not needed but good to use if you have one that is all, I do most of the work with a tenon saw, then pairing chisel then router plane, if you can get it straight from the saw then great but I like sneaking up on the line because I like a good fit not too tight and not too loose, the final fit is what I spend the most time on usually.

 

[TheTiddles]

Use a paring block.

 

[Adam W.]

☝︎ That's a really good idea.

 

[hlvd]

Use a bandsaw.
Cut the tenons roughly 1mm too thick, then cut the shoulders.
Clamp a piece of square ended timber to the bandsaw table so it’s touching the blade, just behind the teeth and square to the blade.
Now your bandsaw will take a half kerf skim cut as the blade won’t have anywhere to go sideways.
Doing tenons this way gives you vernier calliper repeatable accurate tenons.

 

[jonn]

Hello,

I have been working on my first workbench and I want to make it look good as I will have to look at it for many years to come.
I have planed all the wood for the base almost to the finished width and thickness. Now I plane boards to the finished thickness with my hand planes, then cut joinery (mortices and tenons), and finally glue boards together to form a component of the workbench base.

How about a Leigh FMT jig FMT Pro | Leigh FMT Pro Mortise Tenon Jig Leigh FMT Pro ? One jig that works marvels when used properly, as I can vouch for. If materials are proper square, you get hairline joints, as shown on their web pages.

 

[thetyreman]

Use a bandsaw.

+1 I've started doing this recently, great when you need to save some time.

 

[Jacob]

I've been doing 1/2" M&Ts recently with mortice machine and band saw. I bought new blade with advice from Tuffsaws which is much finer than my usual 3tpi skip tooth, cleaner cut but slower. The clean cut made a big difference.
The mortice width is fixed by the machine so the key thing is to get the tenons to fit the mortice. What seemed to work really well with this batch was to cut away half the gauge line as is orthodox but often can leave a tight fit.
So it depends on where exactly your gauge lines are. 12mm? 13mm? 1/2" etc.
A trial cut followed by a trial fit, will tell you whether to saw tight to the line or otherwise. A 3tpi cut is coarse and to allow for the roughness I'd need to saw well into the line and not just halve it.