Getting rolling - dadoes, mortises and tenons

[Jack_Ervin.]

Chris,

I am on board with the hand tools group. I may use a power router on part of the sliding dovetail but plain to use chisels on the mortises. I do have a small Lie-Nielsen router plane and side rabbet planes that I can adjust the dovetail with. My plans now are to chop and pare the mortises using guide blocks. I may use my drill press but I think that the basswood that I am using will not resist a sharp chisel.


Jack

[Chris Hall]

Basswood - another term for chisel heaven

[Chris Hall]

By request, here are a few different ways to mortise. I am mortising the long side boards for the handle tenons.

First up, with a router and an 8mm bit and the router edge guide reference to the end grain of the stick, I rough out the hole:

DSC04809-small.JPG (174.12 KiB) Viewed 4093 times

Then I chisel the corners square and that is that:

DSC04810-small.JPG (156.01 KiB) Viewed 4093 times

Second, using a drill press (or, slightly more riskily, a hand held drill), I rough out the mortises. with this method, I first knife the sides of the mortise.

Then I use a 5/16" brad point bit:

DSC04811-small.JPG (138.04 KiB) Viewed 4093 times

Then a second hole - I only drill through slightly more than half way from the face:

DSC04812-small.JPG (148.85 KiB) Viewed 4093 times

A third hole completes the rough-out:

DSC04813-small.JPG (159.1 KiB) Viewed 4093 times

Then I begin to pare the hole clean:

DSC04814-small.JPG (122.19 KiB) Viewed 4093 times

Further along - I always leave the paring of the end walls, along the knifed lines, for very last:

DSC04815-small.JPG (167.16 KiB) Viewed 4093 times

Mostly complete now:

DSC04816-small.JPG (212.61 KiB) Viewed 4093 times

Then out comes a paring guide and I take the cut to the line:

DSC04817-small.JPG (137.39 KiB) Viewed 4093 times

To pare the outer face of the mortise, I place another board adjacent so the paring block can be supported, and clamp everything so it can't move:

DSC04818-small.JPG (159.27 KiB) Viewed 4093 times

Complete to the point where it awaits fitting of the tenon:

DSC04819-small.JPG (165.12 KiB) Viewed 4093 times

Next method: Chopping the mortise entirely with a chisel.

I choose a chisel that is close in size to the width of the mortise - this is where it helps to have a good range of chisel sizes:

DSC04820-small.JPG (134.88 KiB) Viewed 4093 times

The chopping starts at the middle and proceeds outward:

DSC04821-small.JPG (164.53 KiB) Viewed 4093 times

Some people suggest chopping around the perimeter of the mortise to define it at the start, but I think this is bad practice as the chisel will tend to push the opening slightly larger.

I chop and chop until I have gone about half-way through - takes about a minute I guess:

DSC04822-small.JPG (210.08 KiB) Viewed 4093 times

Then I turn the board over and repeat the process on the other side:

DSC04823-small.JPG (156 KiB) Viewed 4093 times

Work carefully as you go, especially as you near the middle - try to avoid a sudden blast through as you may get some interior tear out.

Here I've finally made it through with the chisel:

DSC04824-small.JPG (128.53 KiB) Viewed 4093 times

Then, much like the previous example, I pare until I have cleaned the mortise to dimension:

DSC04825-small.JPG (157.13 KiB) Viewed 4093 times

A couple of completed mortises - the upper boards was routed, the lower board hand chopped:

DSC04826-small.JPG (148.81 KiB) Viewed 4093 times

The handle tenon mortise just completed is not going to be wedged. The other mortises are all for wedged tenons and haven't been pared out yet. They're rough and ready. Lotsa wedgin' and tenonin' on this project!

Any questions, fire away.

[Chris Hall]

Chris..... is that a bit of water applied to the board before you make the cut with the chisel ?
I look forward to videos in the future but at the moment the lack of video is not a hindarence ... your drawings and writing style are very clear ....

That is not water - which would be a bad idea - but Camellia oil.It is a light vegetable oil and helps lubricate the cutting action. i generally use it more for paring than chopping, and more for abrasive woods than ones that are easy to work.

Glad you find the explanations adequate so far as I am balking a bit at dropping $750 on a new video camera!

[rstephenson]

Glad you find the explanations adequate so far as I am balking a bit at dropping $750 on a new video camera!

Chris, before you go ahead and buy a dedicated video camera, have you considered getting a digital SLR such as the Canon Rebel series? It won't be much cheaper than what you're looking at but they shoot HD video and serve as excellent still cameras. Just a thought, might ease the pain a little...

[Koot]

Chris, a couple of questions.

The end walls are .125" wider than the side walls. Looking at your photos the ends and sides look to have the same width. Do you still have to rip the .125" off the sidewalls or am I just not seeing it in the photos?

I can't seem to locate a measurment for the length of the tenons. How far out the do tenons of the end walls run out (stand proud) past the side walls when assembled? I guess another way of asking is what is the finished length ( ? x 9.75" x .5" ) of an end wall?

thanks,
Marv

[yanai]

Hi Chris,

Great explanations with the mortising.

I was noticing that there seemed to be a lot of wedged tenons coming. I've seen a lot of similar yet different methods described and doing them wrong seems to bring about some pretty bad results (loose fits, splitting or cracking of the tenon, etc). I look forward to seeing how you do them.

[Chris Hall]

Marv,


not sure where you have seen that, but the end walls and side walls are exactly the same dimension at 0.5" thick. Perhaps the confusion is in the tenons? The tenons are 0.375" thick, and therefore the tenon board ends are rebated 1/16" on each side. this slight rebating helps conceal any slight irregularities at the root of the tenon where it meets the inside face of the connecting side board.

The tenons need to stick out beyond the face of the connecting board a minimum of 1/16", but 1/8" (3mm) would be better. It is not an absolutely critical dimension- you need enough extra sticking out so that when the sides of the tenon are wedged and flare out, the entire tenon remains proud of the surface. Then you trim the whole thing off flush. Does that make good sense?

Here's a picture of the rebated tenons on the end board for added clarification:

道具箱 rebated end.jpg (44.31 KiB) Viewed 4075 times

[Chris Hall]

Hi Chris,

Great explanations with the mortising.

I was noticing that there seemed to be a lot of wedged tenons coming. I've seen a lot of similar yet different methods described and doing them wrong seems to bring about some pretty bad results (loose fits, splitting or cracking of the tenon, etc). I look forward to seeing how you do them.

I will detail those steps carefully and thoroughly.

[Koot]

Chris,

... Ah, ok, the preliminary drawings gave me the impression the tenons would be proud. So, flush wedged tenons are the plan and that makes more sense to me. Good.

not sure where you have seen that, but the end walls and side walls are exactly the same dimension at 0.5" thick. Perhaps the confusion is in the tenons?

I guess I wasn't at all clear with the other question, sorry. I was referring to what you had written in an earlier post:

..."One point of note that should be borne in mind: the end boards of the box carcase are 1/8" (3mm) taller than the long side boards of the carcase."....

I couldn't tell from the recent photos if you had that 1/8" "taller" difference already machined, and that was what I was asking . It's just a small detail and really not important at this time.

It will be a while before I can start work on this project and maybe I am spending too much time staring at the plans.

Marv