yet another router question - tenon making

[Mike W.]

I have seen Pat Warner's cool tenon maker jig... too complex for me right now. I have one size of tenon that I need to make, over and over. Around

25-30 times. I was thinking that I could just get a rabbeting bit that goes to 3/8" (the length I need) and set the height on my router table so that the bit is at the depth of the tenon I need. Seems like, in theory, it should work. But all of the past posts I have read that have talked about making tenon's with a router or router table havent mentioned this technique. Granted, I haven't seen all the past posts, but I've seen plenty and most have some big complex jig or fixture that you have to build or buy. Am I missing some fundamental aspect of what Im thinking I can do with a rabbeting bit that will make it waaaaay harder than I think it is?

Sorry for yet another newbie question... but remember, you asked for it. :-)

Thanks, Mike

[Shawn]

Why a rabbeting bit and not just a straight bit?

Shawn

[Mike W.]

Maybe I should use a straight bit. My initial thought is that a rabbeting bit has a bearing on it that would prevent the possiblity of a length error. A straight bit would work for me, but I'd have to rely on the fence which is not zero-clearance and could cause some inaccuracy since the boards I'm tenoning are only 3 inches wide. Or I could rely on the miter slot/miter guage... but it seems like either of these allow for inaccuracies in the length whereas a bearing will keep them from occurring.

I'm not arguing... I'm a newbie. I WANT THE TRUTH. :-)

Am I wrong? Should I use straight bit? If so, can you offer any advice to get around the possible problems I mentioned?

Thanks a lot. Mike

and

[Mike W.]

Sorry... posted to main thread.

In response....

Maybe I should use a straight bit. My initial thought is that a rabbeting bit has a bearing on it that would prevent the possiblity of a length error. A straight bit would work for me, but I'd have to rely on the fence which is not zero-clearance and could cause some inaccuracy since the boards I'm tenoning are only 3 inches wide. Or I could rely on the miter slot/miter guage... but it seems like either of these allow for inaccuracies in the length whereas a bearing will keep them from occurring.

I'm not arguing... I'm a newbie. I WANT THE TRUTH. :-)

Am I wrong? Should I use straight bit? If so, can you offer any advice to get around the possible problems I mentioned?

Thanks a lot. Mike

and

[Shawn]

So attach a sacrificial piece of wood to your fence and make a zero-clearance fence.

Shawn

[Mike W.]

OK.. sounds reasonable. One argument I would have if I wasnt clear in my other post is that the bearing would, in theory, reproduce the same results over and over whereas a fence would have to be reset to some distance each time it was set up, possibly introducing some, albeit small(depending on MY accuracy), amount of error each time.

Lets say I already had the rabbeting bit. Would there be a reason to go one way or the other? Does a straight bit cut cleaner than a rabbeting bit or vice versa?

Again... thanks for the advice. I appreciate all of it.

Mike W.

[Mike Alexander]

You can easily make a zero clearance fence on a router by:

- get yourself a very straight piece of scrap, preferably hardwood

- with board to the right of the bit, clamp the far end to the table

- turn on the router (make sure the board is not touching the bit first)

- slowly move the board into the bit, until the bit is covered

- without removing board, turn off router and wait for it to stop

- rotate your newly created fence to where you want it, and clamp it down

To make it easier to keep your board square to the fence, and to reduce tearout, use a backer block (a big piece of scrap) to push your boards through. Make sure the corners of the backer block are square, or your tenons won't be.

...Mike

[Mike Alexander]

Tenons don't generally need to be exactly the same every time, because they are hidden inside a mortise, and you should be leaving the tenon a little shorter than the depth of the mortise for the excess glue. If they are through tenons, they obviously won't be hidden by the mortise, but in this case, your best to make them slightly long, and then flush cut and/or sand them to be flush.

Both will give you a clean cut, but I don't know how you would safely run the end of a 3" piece across the bit using only the bearing as a guide. Also, it will be tricky to keep the piece straight as you run off the bearing, unless you were also using a miter guide. The piece is too small to use a fence with a gap, so you would have to use a zero clearance fence, and you can't make a zero clearance fence with a rabbeting bit, since the bearing gets in the way.

...Mike

[Wes Stewart]

|Sorry... posted to main thread. | |In response.... | |Maybe I should use a straight bit. My initial thought is that a rabbeting |bit has a bearing on it that would prevent the possiblity of a length error. |A straight bit would work for me, but I'd have to rely on the fence which is |not zero-clearance and could cause some inaccuracy since the boards I'm |tenoning are only 3 inches wide. Or I could rely on the miter slot/miter |guage... but it seems like either of these allow for inaccuracies in the |length whereas a bearing will keep them from occurring. | |I'm not arguing... I'm a newbie. I WANT THE TRUTH. :-) | |Am I wrong? Should I use straight bit? If so, can you offer any advice to |get around the possible problems I mentioned? | |Thanks a lot. |Mike

First off, I think you confuse length and thickness (width) of the tenon. The length is the dimension that describes how far the tenon will extend into the mortise. The thickness seems to be what you are concerned about.

If you use a bearing guided bit then the depth of cut is controlled by the distance between the bearing and the edge of the bit. This means that the thickness of the tenon is totally dependent upon the thickness of the stock.

Normal practice is to cut the mortise and then size the tenon to fit. If this is the case, then you will have to fine-tune the thickness of the stock to use a bearing guided bit. If on the other hand, you have control over the mortise then the rabbeting bit will do the job; however, every piece of stock *must* be the same size, or you will be tweaking *every* mortise.

[Mike W.]

Thanks, Wes.

I thought I had them backwards too, but the plans I was looking at had them listed that way. Maybe the plans are confusing them (with illustrations so it would 'show' and you do it the way you see it anyways) or I'm misunderstanding the plans.

As far as having the exact same mortises.... I struggled hard with this. I tried quite a few ways going through lots of cheap lumber to figure out how. I ended up makine a jig (my first real one... and I'm fairly proud of it) that would allow me to make the same mortise over and over and over again as long as the wood is the same size, I'm using the same router template guide, and I want the mortise centered... I guess that makes it more of a fixture. So anyways, your point is well taken and I think I have that part solved. So a bit that allows for a repeatable rabbet on each side of the board still sounds like its in the running for my tenon making winner.

Let me know if you disagree.

Thanks, Mike W.

[Lowell Holmes]

Try your way and make some practice joints. Keep tweaking it until you get the results you want. I always make a prototype joint when making one that is different from what I've tried before. :-)

and

[Bridger]

there are lots of ways to cut tennons. don't get too focused on doing them entirely on the router table.

in your description you don't say whether you are running the stock through vertically or horizontally, although the idea of using a rabbet bit to control tennon length implies that you are running it horizontally. depending on the length of your pieces it may be better to run them vertically.

you might want to make a table saw sled with hold downs and stops to cut the shoulders. this will do a good job of controlling tennon length. the sled will be generally useful for other things as well.

Bridger

[Herman Family]

Your method will work. Pat's method will work. There are probably a dozen other methods. The great thing about most woodworking is that there are often many ways to accomplish the same task. The major thing to consider is that the proper material is removed from the tennoned piece with the equipment you have at hand. It is a great idea to try and perfect each method, as they all have a bit to teach you.

I've made a bunch of furniture with mortice and tennon joinery with only a straight bit on the router and a not too decent a fence. The real key is to measure your setup and make sure it corresponds to what you want to do. The other thing to try is a few test pieces.

and