Mr. Berger: How should I cut the mortises in round mahogany bedposts? Should I cut them in the square stock before I turn the posts, or should I wait until after turning and try to make some sort of jig to hold the posts under the mortiser?
The head board is a frame and raised panel affair with top and bottom rails. If I cut tennons with shoulders, the rails will not seat tightly against the round posts. I will much appreciate som guidance on how to go about this task.
Thank you, Hadley
Replies
Hi Hadley,
Great questions, and you appear to be on the right track with your ideas.
Ernie Conover once showed me a great jig to produce tenons in a round spindle. That jig was photographed in this article. I also included a crude drawing below. Basically, the spindle rests on the angled support blocks, and then is clamped securely while you bore the mortises.
View Image
Your idea to cut the mortises in square stock is also a good solution. If you go this route, there are a few tips to keep in mind:
1. Make sure the spindle billet is centered perfectly on the lathe when you go to turn, or else your mortise will be off center on the final turning.
2. Be very careful when turning the mortised section because you greatly increase your chances of tearout. There isn't any material to support the grain and your tool can knock the corner of the mortise right off. The same is true in the sanding phase. One trick is to temporarily fill the pre-cut mortise with a scrap tenon so that your turning tool has something to cut. Then remove the scrap after the turning is complete.
I'm going to ask Ernie to chime in on a technique for fitting the shoulders to the round spindle. I've done this only a few times and I went through the trouble of hand chiseling the tenon shoulder to the contour of the spindle to make it fit properly. It is a fussy task.
- Matt
Edited 8/14/2006 12:22 pm ET by MBerger
I have cut quite a few mortises on turned posts using a plunge router. I make a jig to hold the router just above the turning while it's still on the lathe. Using the indexing wheel of the lathe, one can cut mortises at perfect 90 degrees from one another. By leaving the piece on the lathe, the taper (if any) is taken into account. Curved shoulders on the tennon piece can be done on the drill press if you will accept using a floating tennon. I have used both forstner bits and hole saws to do this. You have to waste most of the material on the bandsaw first so that the drill bit only takes a small bite. You also have to back up the cut with some hefty scrap or you will get way too much tearout. I prefer using a forstner bit, but sometimes large ones (over 2") are hard to come by or are very costly. The hole saw option is OK and is cheap. I like to tune-up the hole saw by grinding it to "just" thread down to where the locking pins engage, thus reducing any slop to a minimum. It will create a racket while cutting but the cut is surprisingly good. A taper can even be accomplished using this drill press approach by elevating one end of the tennoned piece. Needless to say, everything must be clamped very securely when doing this operation. If something gets loose you will have an event to remember.
Mr. Berger: Thank you so much for your tips on mortises in round stock. I will be interested in Mr. Conover's comments also.
Kindest Regards, Hadley
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