Replies

1. 
   daverichards | Oct 18, 2010 06:59pm | #1

   Are you reworking the chair design as you go or drawing out plans? If I were doing this I would draw out, on the computer, a 3D model of the crest rail, seat block and splats. Then I would create either full size templates or at least clearly dimensioned patterns from both the bottom of the crest rail and the top of the seat block.

1. 
   Jfrostjr | Oct 19, 2010 01:28pm | #5

   Reworking the chair?

   Dave,

   No, I am not reworking the chair, I am reworking the design. I have full scale drawings from the original work.

   I often find I am dissatisfied with a piece when it is finished so, after a few months, I start tweaking: "that curve is not 'fair' to my eye", so I rebuild it or build a new one and throw the old on the burn pile. As to the chair, I decided 2 splats was not enough and went for 4 in a different configuration. I changed the cant of the front legs and a couple of other things. 

   Thanks for the suggestion.

   Frosty

2. 
   RalphBarker | Oct 18, 2010 09:56pm | #2

   I haven't tried this at home

   I haven't actually done this, so take my thoughts with at least one grain of salt. It seems to me that the template jig would need two parts - a curved backer board that matches the curve of the chair seat and the crest rail, and what i would call an overhang that contains the actual template to guide the guide bushing. I'd do some sort of indexing pin set up at the edges, so you're sure that the work pieces are consistently centered within the jig. I'd envision the layout being done on a large surface with a beam compass to scribe the arcs at the appropriate radius. Make sense?

3. 
   RalphBarker | Oct 18, 2010 11:01pm | #3

   sketch

   This is the sort of thing I was envisioning, but you may or may not want the bottom layer. As long as you index to the centerline of each of the workpieces, the alignment should fall into place. But, again, I'm sort of talking through my hat here.

   
1. 
   Jfrostjr | Oct 19, 2010 08:02am | #4

   Mortise solution?

   Ralph,

   I think we're on the same page. My subconscious often takes over over with problems like this. Last night, during my middle-of-the-night  'drain', it suddenly struck me that a 36" trammel for the router would provide the proper layout curve for the template. Your centerline idea would provide proper alignment when routing both top (crest rail) and bottom (seat board) pieces. Nothing has been glued as of this time.

   Thanks for the prompt reply, Frosty

4. 
   daverichards | Oct 19, 2010 01:49pm | #6

   I see

   "No, I am not reworking the chair, I am reworking the design."

   That's what I meant. Sorry.

   "I have full scale drawings from the original work."

   I was suggesting that by drawing a 3D model of the chair, you could make the desired adjustments and pull the information you need from the model to locate the mortises for the splats. That information might be just the dimensions for a trammel if that would work or it might be printed patterns for both the crest rail and the seat block.

   It sounds like you may have it worked out anyway so my suggestion may be moot.

   Dave

5. 
   Jfrostjr | Oct 19, 2010 05:10pm | #7

   Mortise locations

   Ron,  

   The crest rail is curved  and the back splats will run from the crest rail to a seat board. (There is no back apron.) The mortises on the top and bottom must be spaced in exactly identical positions for the chair to look right. I plan on using a bushing guided up-spiral bit to plunge the mortises but piercing the template accurately on the curve is (maybe was) a problem.

   Now I believe that if I mount the router on a 36' long trammel I can match the curve on the crest rail. Then a simple center-line alignment will get the job done accurately. Agree?

   Frosty

1. 
   user-64052 | Oct 19, 2010 05:49pm | #8

   why not just make a jig out of plywood or mdf to match your curviture. place glue blocks on the edge of the jig to limit mortices. clamp the jig to the seat and route them away. if your slats enter the seat at an angle , that creates another problem with the curviture, if not just elevat the one end of the jig to the desired angle and secure to the seat.

   the other is to use a drill press and if the curviture of the back of the seat matches the curviture of the splats, then you will have an equidistant point to use for a stop and just rotate the seat to where you want to drill, I use end mills on my drill for mortices.. this if you are setting up for a batch production. for just a few, it is more than likely more proficient to do them by hand. sometimes we tend to spend more time farting around to do these setups than it woulld take to do by hand. it is usually more rewarding doing it by hand anyway as it then gives you the feeling that you actually accomplished something

   ron

1. 
   Jfrostjr | Oct 20, 2010 09:53am | #10

   Hand cut mortises

   Ron,

   I certainly have considered hand-chopped or drill press plunged mortises. But I doubted my ability to measure - and cut - precisely enough to ensure the splats would be parallel and equidistant. Errors that would be highly visible on the chair. I am aware of the suggestions of Mel (see below) as a solution.

   Frosty

1. 
   user-64052 | Oct 20, 2010 10:45am | #13

   why bother responding when one has such idiotic responses like those

   ron

1. 
   Jfrostjr | Oct 20, 2010 12:52pm | #14

   Idiotic responses

   Ron,

   Some of us, over the years we have spent on this forum, have developed relationships that are sometimes 'silly'. After the serious discussions and helpful suggestions have been dealt with the posts often drift into what you call 'idiotic'. It is just our form of humor.

   I'm sorry you were offended.

   Frosty

6. 
   9619 | Oct 20, 2010 07:13am | #9

   Frosty,

   Why not just make the mortises overly large and fill the voids with Bondo?

   Tight fitting M&T joints are a modern obsession.   "Back in the day" when woodworkers were real men, they just made the mortises a little sloppy and draw-bore-pinned them.    I think the real problem is quiche.  Too many woodworkers are eating quiche these days.   Or maybe the problems started when the liberals put flouride in the drinking water.   The world really went downhill after that. China didn't start making bad quality woodworking tools until well after we started putting flouride in the drinking water.   

   Have fun.

   Mel        

1. 
   Jfrostjr | Oct 20, 2010 10:01am | #11

   Practical solutions from an engineer!

   Mel,

   At last a suggestion that is pragmatic. I too am an engineer and "when you gotta do-it, do-it!, dammit!"

   Bondo - why didn't I think of that?  Well - because we have a lot of Apples in Michigan and alar acts adversely on Bondo. The joints would relapse into a state of sloppiness that would disqualify me from my association with this fine group. You wouldn't want that, would you?

   Then again, loose joints would permit the splats to move with the body - and perhaps provide a more comfortable seating experience. I'll have to think about that.

   Good to hear from you.

   Frosty

2. 
   RalphBarker | Oct 20, 2010 10:18am | #12

   Falling flat with a splat

   You may be onto something with the Flouride, Mel. As I recall from my first trip to China with Marco, the woodworking tools back then were quite satisfactory. I'm not so sure about the quiche, however, since I can't remember the last time I had any.

   The issue with splats, compared to conventional M&T joints, is that they resemble [insert name of your favorite wimpy class of persons here] - no shoulders to hide any misfits. Plus, the splat is generally too small for a decent draw-bore pin, not to mention that we would be pinning into end grain.

   The Bondo idea may have some merit, though. Does Woodcraft carry that in Oak?