Finger joint questions

jere · Post by **jere** » Sun Jul 07, 2013 12:23 am

I made a simple screw advance jig to start making fingers joint with the table saw. I don't have a dado at the moment so I am working with what I have. The main question I have right now is how much space should I leave between the the joints? should I leave a crack of daylight inbetween or get them to the point I have to hammer them together?

pieceseeker · Post by **pieceseeker** » Sun Jul 07, 2013 7:39 am

If you intend to use glue, I would think somewhere in-between those 2 extremes. Others with more experience in those areas should chime in.

How about a pic of that jig?

dusty · Post by **dusty** » Sun Jul 07, 2013 7:57 am

jere wrote:I made a simple screw advance jig to start making fingers joint with the table saw. I don't have a dado at the moment so I am working with what I have. The main question I have right now is how much space should I leave between the the joints? should I leave a crack of daylight inbetween or get them to the point I have to hammer them together?

Really well made, proper fitting finger joints can be pressed together by hand and will be somewhat difficult to dismantle. No open spaces between fingers but no pounding required.

The critical steps to finger joints all occur before the first cut; the secrets are in the setup.

jere · Post by **jere** » Sun Jul 07, 2013 12:50 pm

Just made it from some stuff that was around the garage. I tacked a bolt to an "L" bracket, drilled out the L bracket so the all thread would go through.

Here is some blade width test cuts on some scrap with a quarter turn difference between them. They are going the wrong way on the graining of the wood so that is why some of them are broken. It was easier to just do some fast dirty cuts with out clamping this way

charlese · Post by **charlese** » Sun Jul 07, 2013 1:28 pm

Most often box joints are made into end grain. I've fount this to be the only practicable way.

jere · Post by **jere** » Sun Jul 07, 2013 2:12 pm

charlese wrote:Most often box joints are made into end grain. I've fount this to be the only practicable way.

Yeah I think I see your point, I will try again with the wood turned the other way. At least I got the spacing close, I am starting to think I need a smaller diameter of all thread. That might give me some more fine tuning.

pieceseeker · Post by **pieceseeker** » Sun Jul 07, 2013 2:26 pm

Instead of using that long pipe for a handle, I might try cutting a 6" circle out of plywood with a hole in the middle to bolt to the screw. That way, it would act as a degree wheel if you mark it at the edges. That should give you incremental adjustments for the cuts.

Just have to measure how far the screw moves with 1 turn of the wheel.

nuhobby · Post by **nuhobby** » Sun Jul 07, 2013 3:58 pm

charlese wrote:Most often box joints are made into end grain. I've found this to be the only practicable way.

I did one the other way.... had to re-glue a few fingers. But in the end it was easy to plane!

[ATTACH]22094[/ATTACH]

charlese · Post by **charlese** » Sun Jul 07, 2013 6:57 pm

jere wrote:Yeah I think I see your point, I will try again with the wood turned the other way. At least I got the spacing close, I am starting to think I need a smaller diameter of all thread. That might give me some more fine tuning.

Yep! looks like your fingers are nice and tight! They look good!

Your frustration using screws to make adjustments was mine also. That's why my present box joint jig is adjusted with hammer taps. This is a tip I got from an old TV show about routers. Works fine with a saw too!

IMO - screws are fine for 1/4" box joints that are up to 5 or 6 inches long, but in order to get joints of up to 12" or so, you need hammer taps.

jere · Post by **jere** » Mon Jul 08, 2013 12:50 pm

pieceseeker wrote:Instead of using that long pipe for a handle, I might try cutting a 6" circle out of plywood with a hole in the middle to bolt to the screw. That way, it would act as a degree wheel if you mark it at the edges. That should give you incremental adjustments for the cuts.

Just have to measure how far the screw moves with 1 turn of the wheel.

Thanks for the idea, I ended up drilling a hole in the middle of the tube, so I can do partial turns. With the 3/8ths all thread it turns out 4 full turns equals the width of the saw blade plus the play that seems to come from the play in the sled tracks and the saw blade. Not sure why there is play in the saw blade maybe it's normal!?