First of all, I want to state for the record that, after thinking clearly and receiving a response from another subscriber, I do not blame you for the lack of a response to my original post. There seems to be a problem when the initial response to a post does not fully answer the initial question and requires further replies. The FW website provides a “REPLY” button, but the system appears to not complete the exchange. I have already conveyed this concern to David Heim, Managing Editor. I was getting very frustrated by the lack of a response and other disasters were pushing my patience. With that stated, let me restate my problem as I still need advise in order to save time and expensive wood. The following description is as detailed as I think necessary to create an accurate picture of the design, so I hope that it will not exceed any posting limits. If necessary, I can attach drawings in a following post. <!—-><!—-><!—->
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I am building a baby crib for my grandson on a tight schedule. The major challenge is selecting the best method for cutting mortises for the slats/spindles. The crib is a convertible design that can convert to a full-size bed. The back of the crib is the future headboard and the front of the crib is the future footboard. When converted to a full-size bed, the crib sides will be replaced with standard sized bed rails. The crib sides consist of a straight horizontal bottom rail, two end (straight & vertical) stiles and a curved top rail. The rails attach to the end stiles with mortise and tenon joinery. The field (area enclosed by the rails and stiles) of each side contains 5 vertical and parallel slats (spindles) which are ½” thick, 1-5/8” wide, and of varying length; the spacing between slats is 2-1/8” and the edge profile is half-round. I am planning to make the mortises in the top and bottom rails for the slats to match the end profile of the slats rather than create a new reduced in size profile, which will require additional work (although it does cover imperfections in the joint). The bottom rail is straight and horizontal. The top rail, starting at the back (headboard) stile is horizontal creating a height of 35-3/8”. It starts curving downward in the first 2-1/8” space. The curve continues downward at an increasing angle into the 3rd (middle) slat where the curve reverses to return to horizontal as it approaches the front end stile. The width of the top rail throughout the curve is 2-7/8”. The height of the side at the front (footboard) is 30-5/8”, creating the 4 ¾” offset. None of the slats are perpendicular to the top rail and the angles range from 4.5-degrees to 25-degrees. I am planning to create the curved top rail by edge gluing 3 boards sized and shifted to optimize both wood use and provide a perpendicular surface (as much as possible) for cutting the mortises in the side top rails. The 2 mortising methods that I am considering are: 1) using a drill press with a ½” Forstner bit to drill overlapping holes, or 2) using at template and a router with a guiding bushing and a ½” straight bit. I have already read your book on the sections indicated in the first reply, but I am looking for the optimal and least risk method for this situation. For the head board and footboard where the both rails are straight and parallel, I think that an incremental router jig (one that contains a slot for a router guide bushing for cutting the current mortise and an offset pin that sits against the edge of the adjacent mortise) is the optimal solution. The wood is pecan, which has already given me tear-out/chip-out problems when the tool cutting edges/speed/attack-angle are not optimal. <!—-> <!—->
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Another associated problem that I have is that the top of the crib side is capped with a curved board, which is 3” wide by 1” thick. A butt joint between the top rail of the side panel and the cap board requires an exacting match so that no gaps exist. One solution is to create a groove (dado) in the cap board, but I do not know how to create a groove/dado in a board with both concave and convex surfaces. I am open to any and all suggestions as this is my first real venture into working with joinery in curved surfaces. <!—-><!—->
Replies
Hi,
Given the angled nature of the mortising that you're confronted with I would say that the drill press would be an easier method. IF it has a tilting table. Then you can angle the table for each set of mortises at the correct angle. Get your two outside holes drilled first for each mortise and then finish up the middle of the mortise. If you're careful you should be able to clean up the mortises with a series of bit passes, but take it slow and make sure the piece is clamped to a fence to prevent any problems.
As for a groove in the curved cap piece, the cap piece is curved on two sides but flat on the other two, as I read your note. Get a slotting cutter and mount it in your router table. It will have a bearing on it that will follow the curves. You will have to get the right sized cutter in order to get the proper depth for your grooves.
I'm out of town at noon today for a few days so if you have any more questions I'll check back into the site in a few hours. Best, Gary
Thanks <!----><!----><!---->Gary<!----><!----> for your quick response and checking for follow-up questions. While seeking advice on this project, I made a full-sized drawing on a sheet of ½” MDF and reproduced the cap and top rail profiles on another piece of MDF for templates. When I got your recommendation to use a slot cutting bit to cut the groove in the cap board, I found a Whiteside set with the height range needed; it cuts a ¼” deep slot. I modified the drawings to account for the ¼” groove in the cap and added tongue on the rail. With that done, I have been going over the sequence of steps to make the parts. Here is what I have come up with.<!----><!----><!---->
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Curved Top Rail:<!----><!---->
1. Mill the 3 pieces that will be edge-glued to create the blank for the curved top rail. There will be 1 mortise in the top piece, 1 mortise in the middle piece and 3 mortises in the bottom piece.<!----><!---->
2. Cut the tenon on one end each of the top and bottom pieces while they are still square.<!----><!---->
3. Edge-glue the 3 pieces (now or drill the mortises first?).<!----><!---->
4. Cut the bottom curve (completely or leave flat steps above the mortises?), but leave the top edge straight and perpendicular to the slats, creating a resting base on my drill press’ auxiliary table, which does not till due to it’s size.<!----><!---->
5. With the piece clamped to the fence on the auxiliary table, drill the mortises with a Forstner bit with overlapping holes.<!----><!---->
6. Complete the curved profile.<!----><!---->
7. Mortise the straight Bottom Rail.<!----><!---->
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Cap (cross-section profile is 1” thick X 3” wide):<!----><!---->
1. Mill the 2 pieces that will be face glued to create the blank.<!----><!---->
2. Cut and smooth the profile on the bottom side only. Leave the scrap on the top side to provide more stability while routing the 7/8” wide by ¼” deep groove on the router table in multiple passes.<!----><!---->
3. Cut and smooth the top profile.<!----><!---->
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Any comments this plan will be greatly appreciated. I have found from experience that doing a step in the wrong part of the sequence can significantly increase time and difficulty. Thanks again for all of your help. Dravo<!----><!---->
Dravo,
I'd glue up first, flatten this new board and then do your mortising. As for shaping, I always do my shaping after my joinery is complete. This way I have flats to work off of as you mention. Good luck. Gary
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