Cutting a groove or dado in very hard wood.

[Andy Kev.]

If you needed to cut a groove or dado in something very hard e.g. rock maple, would you use a plough plane or a chisel (assuming that the groove is shorter than say 12 inches in which case I guess a chisel would start to look impractical)?

If one went for the plough plane, are there any particular tips other than keeping the blade very sharp e.g. would it be advisable to take only very shallow cuts?

You may have guessed from the above that I have set myself the task of cutting a 1/4" groove in a 10" long piece of rock maple and I thought for once that it would be a good idea to ask a question before jumping in with both feet.

 

[dzj]

If it is a groove, you could go with a plough plane. For a dado, there are dado planes, but a 1/4" one might be hard to find. Easier to scribe lines and then saw to required depth and take out waste with chisel and router plane.
If in doubt, it always helps to make test cuts on a scrap piece.

 

[AndyT]

I'd make sure I defined the sides really well before cutting down. So start with a nice clear knife line on either side. Then cut a notch to each line and saw down almost to full depth. I'd definitely do this for a housing (dado) and probably for a groove if I wanted to be safe.
After that, chiselling followed by a plane or hand router.

With very hard or wavy grained wood there is a risk that a planed slice at the surface will split beyond where you want it to go, hence the need for clearly defined boundaries.

 

[bugbear]

I'd make sure I defined the sides really well before cutting down. So start with a nice clear knife line on either side. Then cut a notch to each line and saw down almost to full depth. I'd definitely do this for a housing (dado) and probably for a groove if I wanted to be safe.
After that, chiselling followed by a plane or hand router.

With very hard or wavy grained wood there is a risk that a planed slice at the surface will split beyond where you want it to go, hence the need for clearly defined boundaries.

Haywood illustrates all this in several (Haywood was an early recycler) of his books.

Here's a modern transcription:

https://wingnutworkshop.wordpress.com/2 ... t-part-ii/

BugBear

 

[Trafalgar]

Dado (Am. Eng.) Housing (Br. Eng.):

1. Knife the sides (shoulders), form a small trough in the waste with a chisel in which the saw can run;
2. Mark ends to depth;
3. Saw the sides to depth, against a batten if necessary on long joints;
4. Clear bulk waste with chisel leaving a fat sixteenth to an eighth or so to finish with the router plane;
5. Work to final depth with router plane with pointed cutter installed.

Do no. 5 in turn at each depth setting if several dados are being worked. This will assure they finish at exactly the same depth.

If working through dadoes then use the router plane entering from each end toward the middle to keep the outside edges clean, i.e. no blowout below the depth line.

 

[G S Haydon]

Sounds silly Andy but as you said "10 inches long piece of rock maple" it implies working with the grain in my mind. Or as the people who have responded are you working the width of the board? If you are working across the advice is sound. If working with the grain, light cuts and a sharp iron in your plough.

 

[woodbrains]

Hello,

As said above, a groove suggests along the grain, so a plough will be perfect. A plough has limitations if cutting across the grain, dado ( do we not call these housings in Britain?) but will work in some instances. For instance fence rods limit the distance from an edge. A router plane is ideal, or a combination plane running on a clamped on batten as a guide.

Clarify which cut you want to do and what tools you have. In fact, are you thinking of getting a tool to do the job, if you are not equipped? Then someone can advise more precisely.

Mike.

 

[Trafalgar]

Maple, while hard, cuts very cleanly. There's no reason a groove run on a sensibly selected piece of stock won't be very crisp indeed. If running on highly figured maple then pre-knifing the lines can make sense.

Your setting, approach, tooling, and overall methodology need to be confirmed on a piece of scrap stock.

 

[Andy Kev.]

Thank you all very much indeed for the replies. I now know what I need to do.

I should have made clear that I'm going to start with a couple of grooves with the grain and then possibly add a couple of housings (thanks Woodbrains*).

*After Woodbrains' post I looked up the etymology of "dado". Apparently, it first popped up in Italian architecture some centuries ago and may have even got in to Old Portugese from Arabic.

So "housing" it is then (except of course when communicating transatlantically).

 

[Trafalgar]

Lay out the workpiece in a way that will have you conveniently cutting the groove with the grain. You will want to rip to width with an eye toward producing mild grain at the edge to be grooved whenever possible. Don't paint yourself into a corner by leaving a gnarly patch at the edge where the groove(s) will be run.

The fastest and most indelible way to learn all of this is to have the plane pull up a very visible chunk from a groove, rabbet, or dado on a wide panel glue-up done in expensive, figured stock.

 

[Andy Kev.]

Lay out the workpiece in a way that will have you conveniently cutting the groove with the grain. You will want to rip to width with an eye toward producing mild grain at the edge to be grooved whenever possible. Don't paint yourself into a corner by leaving a gnarly patch at the edge where the groove(s) will be run.

The fastest and most indelible way to learn all of this is to have the plane pull up a very visible chunk from a groove, rabbet, or dado on a wide panel glue-up done in expensive, figured stock.

This is cracking advice which you are giving me and I have noted it all. And I will, of course, practice on a bit of scrap.

When I was planing some of this rock maple I turned to my bevel up smoother from Veritas. I had been beginning to think that buying it had been a mistake as I had hardly used it (managing to get most of my smoothing done with my No 7 jointer) but the maple pieces are smallish and so I used the BUS with its shorter length and steeper bevel. It really came in to its own, doing a wonderful job and producing the loveliest finish. I was surprised at the amount of effort required to push it through the cut but what results!