Replies

1. 
   SgianDubh | Mar 21, 2002 08:47am | #1

   Normal practice with a hollow chisel morticer in my experience Mike is to flip the timber and plunge from both sides for a clean exit. I sometimes see a recommendation to plunge right through into a sacrificial block below, but again-- only my experience-- this trick always fails. Slainte, RJ. 

   I used to be positively apathetic, but now I just couldn't care less.

1. 
   WannaBeJazzer | Mar 21, 2002 07:36pm | #2

   Thanks Sgian,

   did you attempt the flipping technique with (somewhat) deep mortises - mine are to be 2".  So I'm curious if there would be offset or missalignment.  which, of course could make fitting the tenons more tedious ;)

1. 
   SgianDubh | Mar 22, 2002 04:45am | #3

   Lots of mortices over the years Mike, from tiddly, shallow double mortices, to deep ones, even forked middle rails  in full size entrance door stiles, some up to 4" or 5"  deep.

   Square your lines across the inside edge, transfer them across the face, and square the lines across the exit face. If you're chopping multiple mortices in lots of stock that's all the same dimension you can make a wee U shaped jig that fits snugly around the stile to transfer the mark, which makes marking a piece of cake.

   Hollow chisel morticers often have mortise length stops that can be utilised, and there is also the option of making a marked false bed that might be useful for repetitive work that sits on the bed of the morticer. 

   There is a routine in joinery that starts at the surface planer, or US Jointer. Flatten a wide face, and mark it with a face side mark, often known colloquially as a 'pigs tail'---basically a pencilled looping line  that starts in the middle of the flattened face and ends at the hollow edge. Then square the hollow edge to that first pig-tailed face, i.e., the pig-tailed face goes against the surface planers (jointers)  fence set square to the table, Put a V on this edge so that the bottom point of the V coincides with the end of the pigs tail. Now you have two marks on every single piece of timber that you can use as a permanent references for all further operations. For instance, in setting out a frame, put all the pig tail faces 'up'----- and all the edge V's facing 'inwards.' All subsequent measurements and marks are referenced and made from these two original 'faces'. It's an ancient but reliable technique for not losing track of what goes where, and which way.

   When mortising through mortises on a hollow chisel morticer for instance, you might put the pig tailed wide face to the back fence, chop about halfway through, flip the piece of timber end to end keeping the pig tail to the back, and chop from the other side. The mortice will meet in the middle all things being equal. You can of course reverse the routine, but it's the routine that's important for consistent joinery success.

   Hope I made sense, but get back if I didn't.

   Slainte, RJ

   I used to be positively apathetic, but now I really couldn't care less.

   Edited 3/21/02 9:50:27 PM ET by Sgian Dubh

1. 
   WannaBeJazzer | Mar 22, 2002 08:31pm | #4

   Wow, for a guy who's motto is something like "i dont give a 'rip'", that was a generous reply ;)

   I'm anxious to try your methods!

   And sometime if you feel like telling us about what a 'forked middle rail' is I bet we'd be all ears for that one too.  Is that the mating part for a double haunched tenon?

   Thanks again for sharing,

   mike.

1. 
   SgianDubh | Mar 23, 2002 02:41am | #5

   Hopefully- my first effort at loading pics on the new incarnation of knots- these pics will explain.

   The first is a side rail to front rail intersection of a chair where I wanted to maximise the long grain surface mating.

   The other is actually a table rail to leg, a very deep rail for a particular table. Only the top fork here is glued, and the bottom part of the rail can expand and contract thus reducing the chance of splitting the rail. You'll notice there's a bit of slop in the length of the mortise, especially the bottom mortice to allow for the movement.  The meat between the two mortises also helps prevent the inner cheeks from spreading away from the tenon cheeks. Usually a little haunch between the two forks is left, along with a haunch at the top edge of the rail, and these are fitted into a wee groove between and above the mortices and helps prevent the faces of the parts bowing out of line. This applies especially to door construction, see below, where a groove is often worked anyway to carry a panel, and typically grooves run right through.

   In the middle rail of an architectural door, the gap between the forks also serves as a spot to fit the lockset or latch. Some of these middle rails are very wide, so here again- and if it's me making such a door I only glue the top fork. The bottom edge of the rail rides up and down a bit on the panel.

   Take no notice of my tag line. I just put it up because I liked the play on words, and I thought others might get a wee kick out of it too. I'll probably delete it, or change it in a week or two if I can think of something else I consider mildly amusing.

   Slainte, RJ.I used to be positively apathetic, but now I really couldn't care less.

   
2. 
   WannaBeJazzer | Mar 23, 2002 03:21am | #6

   Wow, scanned images and all, your the craftsman, Sgian.

   If you come to Olympia, WA, I'll spring for Pizza and Beer.

   As for your sloagan you could use one of my favorite movie quotes like:

   BraveHeart: Every man dies, not every man really lives.

   Shawshank Redemption: Time to get busy livin' or get busy dyin'. Damn straight.

   Or if you like wretched workman lines try:

   I thought I wanted a career, turns out I just wanted paychecks!

   The fact that no one understands you doesn't mean you're an artist!

   or most appropriate:

   I like you. You remind me of when I was young and stupid.

   I see you've set aside this special time to humiliate yourself in public.

   Too many freaks, not enough circuses!

   not exactly profound, but anyway, thanks again!

3. 
   Seth_Frankel | Mar 23, 2002 04:38am | #7

   Mike,

   If I post sketches will you buy ME pizza at Joe Mama's?

   Seth

4. 
   sschefer | Mar 23, 2002 06:51am | #8

   Sgian...Robert or whatever, I really appreciate your post. I have been trying to think of a way to attach skirts to legs for an extremely heavy marble table top.  I want the skirts to take on some of the support responsibility and I think you just showed me, (with a little modification), how I need to do it. Thanks for once again sharing just a small amount of your obviously infinite wood working wisdom.

   Steve - in Northern California

   If the doctor says you have Attention Deficit Disorder, do you pay attention to him?

   Edited 3/22/2002 11:52:12 PM ET by Steve Schefer

5. 
   WannaBeJazzer | Mar 25, 2002 09:21am | #10

   color me nieve, but is 'Joe Mama's' a place in Oly where we could actually get pizza? LOL.  If so, let's see what you've got!

6. 
   Seth_Frankel | Mar 25, 2002 03:54pm | #12

   Goodness! I've seached the net for Jo Mama's Pizza (it was about a mile from downtown on the eastside) and find nothing. I wonder if they've closed shop. I was last there in about 1994.

   They were known for there ultra decadent, "I can't imagine that on pizza" pizzas. Funny how when you move away you assume that you ol' stopping grounds stay the same! Maybe ask a local if they're still around.

   Best,

   Seth

7. 
   deforestC | Mar 26, 2002 05:50am | #13

   Alas Jo Mamas is no longer in existence, many the fond rememberances of a Leaning Tower and a mason jar of brew... I feel that the advice to keep the same face to the fence and bore from both sides is the only way to go, the blow out from a mortising chisel is quite the disater to behold. In fact when I built an aux table for my drill press setup it was never intended for the chisel to ever touch it!

2. 
   BernieMaas | Mar 23, 2002 06:19pm | #9

   Whenever we've done thru mortises, we've flipped them to prevent blowout.  As one reader suggested a backup block that should prevent blowout doesn't necessarily do that.  As for planing the blowout away - there's no predicting the depth of the blowout.

   Flipping them has always worked best - flip the workpiece end for end  and not side for side.  Not matter how well you've attempted to center the mortise, you're genrally of just a bit and flipping side for side will double the error.

   As another reader suggested, scribe the stat & stop lines of the mortise around to the back side.  Even if there is a slight misalignment, you've got the tenon's shoulder to mask it.

   Bernie Maas

3. 
   chairmake1 | Mar 25, 2002 10:55am | #11

   I use the Powermatic and on all of my thru mortises I come from both

   side - just keep the same side of the leg to the fence and all

   works well.