OldTools Archive
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89126 | Frederick Walker <walkerz@p... | 2001‑01‑29 | Mitered breadboard joints |
Can anyone point me to (or tell me) the proper way of cutting the mitered breadboard ends (in a Galootinous fashion) that are often seen on slant front secretaries? |
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89377 | Don McConnell <Don.McConnell@a... | 2001‑02‑04 | Re: Mitered breadboard joints |
Nearly a week ago, Frederick Walker asked: >Can anyone point me to (or tell me) the proper way of cutting the mitered >breadboard ends (in a Galootinous fashion) that are often seen on slant >front secretaries? I went through my various references, hoping to find one which substantially answered Fred's query. Not having come up with one, and thinking this may deserve some discussion on the list, I've decided to attempt a somewhat detailed reply. Clamping, the historic trade term for this feature, can be done in a variety of ways (simple tongue & groove, and dowels, as examples); but I'm assuming that Fred is referring to the haunched mortise and tenon variety. A few of my older references have good drawings and a couple of layout hints; but, invariably, they gloss over the specific difficulties of executing this particular configuration. (If someone comes up with an older detailed discussion, I'd love to hear about it.) First, a bit on layout. Some of the older references suggest using the pre-formed mitered clamps as layout patterns - knifing around them while they are in place on the surfaces of the main panel. Not having read this before, I haven't tried it; but I think it's a good idea. The primary advantage, as I see it, is that any discrepancy, however slight, from a true 45 degree miter, will be auto- matically compensated for in the layout. My only concern with this approach,would be to have the jointed and mitered surfaces truly squared to the reference surface of the clamp. This should minimize discrepancies in layout from the front to back surfaces of the panel. Another obvious aid would be to have the panel stock carefully squared and trued up at the desired final length. Also, at least one of the illustrations shows the miter joint held back just a bit from the front edge of the main panel. Again, I haven't tried this, but think it would be a good idea if you have the luxury of, temporarily, leaving the panel a bit wider than the desired final dimension. If the miter comes exactly at the corner of the panel it can be fairly fragile and unforgiving as one does the final trimming. I would be careful to keep the set-back from the corner exactly equal at both ends of the main panel (maybe between 1/32" and 1/16"?), and then carefully plane that edge of the panel to bring the miters to the corners after the clamp is glued and pinned in place. This would help keep the final clamped panel square. Having defined the thickness and location of the tenons/haunches and mortise/grooves with a mortise gauge, the next order of business is the removal of the waste to create the material for the tenons and haunches on either end of the panel. Obviously, the presence of the miters precludes straightforward sawing or planing operations to accomplish this. So, the object becomes to effectively isolate the waste areas, and then remove it in as expeditious a manner as possible. One strategy to isolate the waste would be to bore a few adjacent or over- lapping holes near the junction of the knifed lines. A forstner bit would be ideal for this, being careful to go as close to final depth as feasible. The cavity formed by this operation (possibly with some clean-up with a chisel) will provide a space in which to run the toe of a back-saw to make initial cuts along the shoulders. Some simple means (such as some strategically placed pieces of masking tape) of determining the depth of the saw cuts would be advisable. Personally, I'd leave a little waste inside the knife lines for later clean-up by vertical paring. Alternatively, one could form a small V-groove by paring with a chisel along the waste side of the knife line; or, simply make use of a trued-up batten to guide the cuts. Once isolated, the waste removal can begin in earnest. A couple of methods come to mind. (I'm hopeful others will have better ideas.) The first would be to split off pieces of the waste by driving a chisel into the end-grain. Needless to say, this will only work if the material is relatively straight-grained and has no significant run-out. In other words, if one were using figured or wild-grained material, this technique is not going to be very useful. The second technique is the use of a bench gouge. The ideal would be to use a gouge which would cut almost deep enough as the wings of it's cutting edge are just even with the surface of the material. As long as you keep the gouge level, laterally, it will be somewhat self gauging if you have surface material on at least one side against which to judge the depth. I would use a mallet and go at it in a very methodical manner - mostly going cross-grain. This allows for a great deal of control, yet accomplishes waste removal in a straightforward and measured manner. The final clean-up can be accomplished with a router. The outboard end of the router can be registered upon a bit of the waste left at the outer extreme of the tenon material or a batten of the same thickness as the panel. If you have left some waste inside the knife lines, this would be a good time to clean it up. Careful vertical paring, registering the chisel in the knife line for the final cuts, should be effective, working either free-hand or with a batten to help guide the cuts. The tenons and haunched areas can then be determined and cut out - to be used as a template for the mortises. The chopping of mortises is, then, fairly standard. Personally, I prefer chopping the mortises prior to ploughing the grooves for the haunches. Plough plane irons tend to run slightly oversized and may obliterate the gauge lines. The last remaining difficulty is the manner of affixing the clamp to the panel. The tenon nearest the miter, and the miter itself, can be glued as well as pinned. However, since we have cross-grain construction, it is best to allow for expansion and contraction of the panel relative to the balance of the clamp. My approach has been to use pins at the remaining tenons, slightly off-setting the hole in the tenon toward the shoulder (a shy 1/32"). This helps pull the clamp tightly into the shoulders. Once this hole is bored, I then knife short lines at the tangents of the hole parallel with the shoulder, and elongate the holes into short slots to allow for movement. These can be opened up with a pad saw if the tip of the blade will enter the hole, or simply chopped out with a chisel. This movement allowance can be calculated using the tables and formulas in Bruce Hoadley's _Understanding Wood_. Needless to say, the mortises need to be elongated a corresponding amount. Hope this helps and I'm hopeful others will share their ideas. Don McConnell Knox County, Ohio |
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89418 | Scott Stager <ccstager@s... | 2001‑02‑05 | Re: Mitered breadboard joints |
I read with fascination Don's reply to Frederick's question, because I may have the need to make something like that to put a front on a portable desktop unit similar to what I understand to be a secretary. But, I quickly became totally confused. I then realized that I didn't really know enough about the "feature" to follow the discussion. Could someone enlighten me further ? I thought I knew what a breadboard end was, but "mitered"? "haunched mortice and tenoned variety"? "pre-formed miter clamps"? Anybody willing to try some ASCII art? Thanks in advance --Scott At 06:00 PM 02/04/2001 -0500, Don McConnell wrote: >Nearly a week ago, Frederick Walker asked: > >>Can anyone point me to (or tell me) the proper way of cutting the mitered >>breadboard ends (in a Galootinous fashion) that are often seen on slant >>front secretaries? > >Clamping, the historic trade term for this feature, can be done in a variety >of ways (simple tongue & groove, and dowels, as examples); but I'm assuming >that Fred is referring to the haunched mortise and tenon variety. ---Superb detailed discussion snipped. > >Don McConnell >Knox County, Ohio > +=======================================================+ Scott Stager |
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89480 | Don McConnell <Don.McConnell@a... | 2001‑02‑06 | Re: Mitered breadboard joints |
Yesterday, Scott Stager asked: >I read with fascination Don's reply to Frederick's question, because I may >have the need to make something like that to put a front on a portable >desktop unit similar to what I understand to be a secretary. But, I >quickly became totally confused. I then realized that I didn't really know >enough about the "feature" to follow the discussion. > >Could someone enlighten me further ? > >I thought I knew what a breadboard end was, but "mitered"? > >"haunched mortice and tenoned variety"? > >"pre-formed miter clamps"? > >Anybody willing to try some ASCII art? After telling Scott, in private, that I thought ASCII might be confusing, I reconsidered. Below is my effort at a few illustrations which, I hope, will begin to answer his questions.. In each case, I have shown only a portion of one end of a panel, and the corresponding clamp (breadboard). As I mentioned previously, there were a variety of ways to affix clamps to the ends of panels. Doweling was probably the simplest. However, this method is not terribly effective in restraining any tendency of the panel to cup. In this regard, a simple tongue and groove clamp was an improvement, and could be made with the use of a matched pair of tongue & groove planes of the appropriate size. ASCII illustration of tongue and groove clamping //////////////////////// | | | | | | Plan view | | Panel end | | | | |________________________________________________| |________________________________________________| <-- Tongue ________________________________________________ |................................................| <-- Groove | | | | Plan view |________________________________________________| Clamp Better yet is a haunched mortise and tenon clamp. The tenons allowed for a more secure affixing to the panel, while the haunch helps restrain any tendency of the panel to cup. Much as the tongue in the previous example. ASCII illustration of haunched mortise & tenon clamping //////////////////////// | | | | | | Plan view | | Panel end | | | | |________________________________________________| |_ _________________ ______________ _| <-- Haunch | o | | o | | o | | | | | | | |___| |___| |___| _________________________________________________ |.. ................... ................ ...| | : o : : o : : o : | Plan view | : : : : : : | Clamp | :...: :...: :...: | |_________________________________________________| Next we come to the mitered, haunched mortise & tenon clamp. This has the same basic features as the previous example, with the exception of the miter. The miter allows for construction which shows no end grain at the most visible portion of the clamped panel. //////////////////////// | | | | | | | | Plan view | | Panel end | | | __________________________________________| | /_ ____________ ___________ ___| <-- Haunch | / | o | | o | | o | | / | | | | | | | / |___| |___| |___| |/ __________________________________________ /.. .............. ............. ....| / : o : : o : : o : | Plan view / : : : : : : | Clamp / :...: :...: :...: | /______________________________________________| In my previous message, I mentioned the suggestion of setting the miter back slightly from the front edge of the panel. As I indicated, then, I think this has some merit because the tip of the miter will not be quite so fragile while cleaning up the surface of the miter on the panel. After the joint is assembled, the front of the panel can then be planed back to bring the miter *just* to the corner. This joint, prior to assembly, will look something like: //////////////////////// | | | | | | | | Plan view | | Panel end | | | __________________________________________| | /_ ____________ ___________ ___| <-- Haunch | / | o | | o | | o | | / | | | | | | | / |___| |___| |___| |_/ __________________________________________ /.. .............. ............. ....| / : o : : o : : o : | Plan view / : : : : : : | Clamp / :...: :...: :...: | /______________________________________________| By the term "preformed clamp" I simply meant that the clamp will have been trued up and the miter executed, then used as a template for laying out the joint on the panel. Hope this helps. Don McConnell Knox County, Ohio |
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89496 | Scott Stager <ccstager@s... | 2001‑02‑07 | Re: Mitered breadboard joints |
Absolutely Excellent Don - totally cleared up my confusion. Thank you so much. The Ascii is superb. It is clear that much of my confusion was based on a lack of knowledge of the terms of the trade on my part. The reference to clamp (breadboard) and the drawing with haunches labled certainly added to my traditional woodworking vocabulary. One followup question. Others have discussed as recently as yesterday the problem of the main panel moving with the season and standing proud or short of the breadboard end. I presume such movement sould cause a gap in the mitered corner, or in a case of board contraction possibly cause a blowout of some sort in the mitre area? --Scott At 08:49 PM 02/06/2001 -0500, Don McConnell wrote: >Yesterday, Scott Stager asked: > >After telling Scott, in private, that I thought ASCII might be confusing, I >reconsidered. --Great Ascii snipped - but you can believe I have it saved. >Don McConnell >Knox County, Ohio > +=======================================================+ Scott Stager |
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89503 | Scott Stager <ccstager@s... | 2001‑02‑07 | Re: Mitered breadboard joints |
At 08:50 AM 02/07/2001 -0600, Scott Stager wrote: >Absolutely Excellent Don - totally cleared up my confusion. Thank you so >much. The Ascii is superb. > >One followup question. Others have discussed as recently as yesterday the >problem of the main panel moving with the season and standing proud or >short of the breadboard end. I presume such movement sould cause a gap in >the mitered corner, or in a case of board contraction possibly cause a >blowout of some sort in the mitre area? > >--Scott > I think I have answered my own question after re-reading Don's originsl cescription, and realizing that Don was showing the full board, not just one end in his drawings. The breadboard end is mitered on only one end! Don says to glue only the mitre and the first tenon next to it. He describes the slots in the tenons to allow for expansion/contraction of the board. Well Duhhhhhhhhh!! --Scott +=======================================================+ Scott Stager |
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