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Bed Jointer Scarfing Carriage


verhoevenc

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So, I'm always looking for a way to do more and more accurate and easier scarf joints. So, I remembered awhile back how some people talked about running things through a jointer... but that was a REALLY bad idea since the scarf surfaces were only 4-4.5" long, and most jointers need atleast 6" to joint safely and effectively. SO, that got me thinking, how COULD you joint something effectively and safely that was less than 6" long, but still get the accuracy of a good jointer!?

I came up with this idea:

jointercarriage.jpg

The reason jointing something short is unsafe is because there's no adequate coverage on either side of the wood on the tables to keep the piece stable, and thus the jointer would eat more, grab, etc. etc. This carriage, although not built, still in the idea phase, I think would solve that problem. What it is is a carriage that has two "feet", the front foot being higher than the back by a value equal to the jointer's set depth of cut (which could be achieved by just making a carriage with one solid flat bed and running it through the jointer at the depth you want, and stopping a little over half way). Then, you want to cut an even higher section, almost bridge like, in the center so that the jointer doesn't keep hitting your carriage, and thus ruining your jig. Then, you attach in a slanted table onto the two sides of the carriage at 13 degrees onto which the neck will be clamped.

To use it, you attach the neck, and set the depth of cut so that both the tall and short leg sit level on their appropriate sides of the jointer. Then, clamp the neck so that it's rough cut 13 degree surface is flat on the pre-feed bed of the jointer. So what you now have is the high foot on the out-feed table, the cutter head under the "bridge" area about to come upon the neck blank, and then the back foot on the pre-feed table. Then, you turn on the jointer, and run the carriage forward stopping once the cutter head has gone through the neck, but not yet reached the lower foot. Then stop the jointer, and lift up the carriage. It may take more than one cut, but you SHOULD end up with a perfect joint... and then just repeat of the other piece of the scarf.

Feedback on the idea?

Chris

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I admire the effort that's gone into it, but it seems like a very eleaborate way of doing something which is achievable in about 5 minutes with a sharp bench plane, or a simple router jig. IMO, there is no simpler way to do a scarf joint than with a handsaw and a jack plane, and they produce a perfect gluing surface, without the risk of scalloping or burnishing which a rotary planer can produce.

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Yeah, I have the router jig, but that by NO means leaves it perfect and ready to glue. And as for the plane, yeah, I agree that works great. Only reason I'm thinking of some other way is because my latest neck is rock bird's eye maple, and it's been giving the plane hell (and it's not a bad plane! Lie Nielsen with a Hok blade!)

Chris

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Chris, very simular to how i do it, but i dont have a jig as such. I have a bunch of 'blocks', with rebated sections in the middle, that screw to the end of a neck blank. One end (scarf) sits on the table, as does the other end (the block fixed to the neck butt). Each block has two sides, for two different angles (one is longer than the other). It takes two seconds to screw the block on to the end (all my blanks are machined to certain sizes), and much quicker and accurate than a hand plane. So, one block might do a 7deg cut one way, or if you flip it over, will do a 10deg cut. Because the block is rebated (to the size of the neck dimensions) it doesnt move, and keeps the scarf face square with the table (even if my bandsaw cut is a little off square)

I like your version though.

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I tried that exact same method Perry, but found that the chipout on the thinnest leading edge was unsatisfactory and the old router/handplane technique prevailed! Still, good to produce a "coarse" stage from which you improve it to a "fine" result which is ready to glue up. The only way I thought of to reduce chipout was to clamp a safety piece of wood on the trailing edge as support.

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I've got a router jig where the angled sides screw on, I spent 1 hour one afternoon making angled sides, and now I have 10,13,15 and 17 inch sides ready to screw on. With that and a #4 plane, it's easy work.

Perry - looking at that diagram, looks like a pretty short edge to pass over the jointer? or is that just my misunderstanding :D

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