Sapele mortise tear out
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16 August 2017 at 6:45 pm #314505
Folks,
I have a big old lump of some red hardwood that was used as a door frame at work. I’ve cut a few slices off it and am making a book rack for the kitchen. I’m chopping 6mm mortices into the ends but I’m finding that when I come to lift out the waste it’s tearing out the edges.
What am I doing wrong?
Regards,
Rowly- This topic was modified 6 years, 8 months ago by Rowdy Whaleback.
when I come to lift out the waste it’s tearing out the edges.
What am I doing wrong?Do you mean the edges that were defined by your mortise gauge? I had that happen the other day (not in sapele). I wonder if, when the grain is very interlocked, the pins on the mortise gauge aren’t enough to sever the fibers along the top. Because of the interlocked grain, when you take out the chip, it pulls away along the edge. What I did was to carefully run my knife along the mortise gauge lines a couple of times to sever the fibers near the surface of the wood. You need to be careful, especially if it is a through or bare tenon. It seemed to help. Let me know if that helps for you, please, if you try it.
17 August 2017 at 3:52 am #314512Are you using a smaller chisel to remove the waste? Pulling it out with the morticer can tear
fibers17 August 2017 at 7:41 am #314515Ed, yes I did try making deep knife walls but still got tear.
Dean, no I didn’t use a smaller chisel (I don’t have one but will try with a screwdriver or something)
Cheers
Rowly17 August 2017 at 7:44 am #314516When I look into the mortise the surface looks like a crust and the interior walls are very fibrous. Is this normal?
17 August 2017 at 12:13 pm #314528I may have just worked this out. I’m chopping cross grain. Is this a real no no for this reason and better drilling and paring?
17 August 2017 at 12:23 pm #314534I feel really daft but marvelling at the learning. Especially with all the material on the Internet. I’m 48 learning new skills. Even learnt that my having cross dominant eyesight is why my sawing was a bit rubbish.
I’m chopping cross grain.
The long walls of the mortise should be long grain (face grain) and the narrow ends should be end grain. So, the mortise runs along the grain. This lets you have a strong face-grain glue joint to the cheeks. If you turn it sideways, then it will tear out along the top, the tenon cheeks will be in end grain and have little glue strength. If you need a piece to run across the grain, like for a shelf, it would be more typical to use a housing or a sliding dovetail. You could cut a few tenons each of which is square along the piece you are joining, but think of them as running in the conventional direction but are only as long as the thickness of piece with the tenons. Chop them in the normal way, not crosswise. This will also emphasize to you the reduction in glue area, so you either need a bunch of those guys, or you need to combine it with a housing. That’s what you see Paul often do…a through tenon plus a housing, but he does it for appearance, partly. He also whacks a wedge into them, often.
17 August 2017 at 8:04 pm #314546Ed,
I’m making something like the book case attached. I made the two “shelf” strips and put tenons on them with rounded ends.
I think what you are saying is that my design was ultimately flawed by a lack of joinery appreciation.
It’s certainly teaching me a lot. I have arched the tops of the end pieces and tried to chisel off the corners. As I did I ended up nearly smashing one of the sides off. This was again because I failed to work with the grain. A bit of sawing and rasping and I ended up with fairly decent curves.Attachments:
You must be logged in to view attached files.As a guess, that little shelf was probably made with housings to hold the shelves. It looks like they added a dowel pin, probably for decoration. Paul’s “signature” for this kind of thing would be to bring a small tenon through instead of the dowel. It would be square, equal to the thickness of the shelf. But, it isn’t needed. The housings are probably stopped on the inside since the shelf is divided into two slats. I’m guessing the movable bookend goes through the space between the two slats and is shaped like a T so that it can slide when there’s no tension, but stay in place when books lean? That’s clever, but make the feet of the T fat enough so that they don’t break! Another option would be to have the bookend project through the gap between the slats and extend maybe a half inch below the bottom of the shelves. Use that portion as a tenon into a mortise in a separate piece. That would be much stronger.
18 August 2017 at 4:49 pm #314566After I discovered Paul’s videos, the first project I made was the dovetail caddy, using a single board of Sapele. I’m glad I did because I learned so much! Sapele’s interlocking grain means that you cannot get a really smooth finish with a plane, you got to scrap! I had to therefore learn how to setup and sharpen a cabinet scrapper, which was collecting dust in my shop, as well as a card scrapper. I haven’t tried cutting a mortise in Sapele, but I can easily see the problems you’ve encountered.
31 August 2017 at 11:47 am #314801Well, I finished my book rack and gave it to the wife for our 26th wedding anniversary! I really liked the geometric inlay lesson Paul does so incorporated that into this project (an excuse to use my ebay aquired Record 044 plough plane). As it happened it needed 26 whole pieces). Im pleased with the final result, it shows the chipped mortice edges and my failure to get a completely smooth finish. It’s handmade and teaches me to be more patient in future.
- This reply was modified 6 years, 8 months ago by Rowdy Whaleback. Reason: Stanley changed to Record
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