Rocker Morticing Jig

[silentC]

Finished my Rocker morticing jig last week and used it on the weekend to cut some mortices for a couple of frame and panel doors. Very impressed - the mortices are perfectly parallel and square and of a uniform size and depth. Now just need to work on tenon cutting.

Here are some pictures:

[Caliban]

Darren I love it.
With such a contraption you could take advantage of roger the cabin boy's inverted predicament, repeatedly and accurately. ;)

[Grunt]

Now just need to work on tenon cutting
I've been thinking about the tenon problem. I'm about to start on a project that has 36 mortice and tenon joints in it. Since my mortices will be cut by a router I'll need to have 36 rounded tenons or square out my mortices.


I think that I'll use floating tenons that way I'll be able to run a round over bit on a length of wood the appropriate thickness and width for the mortices. I'll then cut the tenons the right length.

Seems like a good idea to me.

BTW, good job on the jig.

[bitingmidge]

Wot, no dial gauge?
:eek:

P :D

[BigPop]

I maybe a bit thick and may sound a bit pedantic but what stops the router from moving towards you other than holding it by hand and stopping it. You have the 2 adjustable stops at either end to determine the length and the other adjustable stop at the side to determine where the mortice will be in the workpiece but what stops the router from coming back towards you. (opposite the long micro adjustable stop)??? Just looking at the pics made me wonder.

[silentC]

what stops the router from coming back towards you
Basically, you do. It's not an uncommon situation when using a router to have a fence or a guide on one side of the job only. You just apply a bit of pressure against the fence as you move the router along it.

[silentC]

Wot, no dial gauge?
:eek:

P :D
I forgot to mention that seeing as I don't have a dial guage, I can't call it a precision morticing jig, just a plain morticing jig. My mediocrity is intact ;)

To compensate for the lack of the dial gauge, I set it by scribing a centre line parallel to the long side of the mortice. I put a countersinking bit in the router (anything that tapers to a fine point will do) and holding the router base plate against the fence, adjust it in or out until the countersink point is exactly on the centre line.

Having only used the one setup so far, it may have been a fluke but I actually ended up with equal wall thicknesses on the first go.

I've got some scales for the stop blocks but haven't fitted them yet.

[BigPop]

Basically, you do. It's not an uncommon situation when using a router to have a fence or a guide on one side of the job only. You just apply a bit of pressure against the fence as you move the router along it.

No probs I thought that is the case but then something inside me thought that if you want to have accurate mortices without any chance of slips/stuffups etc that both sides would be held in someway so that the base is all boxed in and all you needed to do was move the router sideways.
It was just a thought that cossed my mind.:):)

Again thanks to this board I have now attained some more knowledge in my quest of turning wood into sawdust :D :D - now to fix this rotten computer :mad: :confused:

[silentC]

the base is all boxed in and all you needed to do was move the router sideways
I suppose if you made a bit of a slip with a mortice it wouldn't be a catastrophe. However there's a common jig made for cutting dados with a router that captures the base like this. You definitely don't want a slip if you are cutting dados or sliding dovetails in the sides of a carcase.

[Termite]

My mediocrity is intact ;)

Nice job Darren. If that is what you call mediocricty then I still have some way to go to achieve it. For some time I've had the plans that Rocker very generously provides, but haven't got my a**e into gear and made one yet, I think you've motivated me.
One question, are you using a spiral bit?
Something that I've been thinking about is the problem of the round ends. There are available a form of hand press that I was thinking of fitting a mortise chisel into (minus the drill) and using that to square out the mortices, any thoughts on the matter.
Kind regards
Termite

[silentC]

Termite,

It's worth the effort because it makes job so much easier.

Yes, I'm using a solid carbide 5/16" spiral bit. I ordered it from Lee Valley (US$28.95) with a few other bits and pieces. Rocker also recommends a 3/8" bit. The 5/16" was fine for the 20mm frames I was making.

The round ends are a pain in the butt. I haven't worked out an easy way yet. I rounded the tenons on this job. I just used a chisel, cut into the base of the tenon on each corner and then dragged the blade up the length of the tenon like a scraper few times until it was round.

I thought of trying the square mortice chisel & bit but I don't have a 5/16" chisel. It might be difficult to get it to go in straight as it will tend to want to take the easy path rather than cutting through the round corners. If everything was rock solid, it might work OK.

The loose tenon as suggested by Grunt is probably the easiest method but you have to cut twice as many mortices and half are into end grain. I might give it a go though because it will solve a few problems.

[silentC]

Re: round ends, I wonder.....

http://www.woodworkingtips.com/etips/2004/09/10/ws/

[echnidna]

Silent, just take a 45 degree chamfer off the corners of the tenons so they fit in the motices snugly.

[BigPop]

Silent, whereabouts on Lee Valley are those bits???
The only one I could find was a 1/4" and I am after a 3/8".
Thanks

[silentC]

Silent, whereabouts on Lee Valley are those bits???
The only one I could find was a 1/4" and I am after a 3/8".
Thanks
Here you go: http://www.leevalley.com/wood/page.asp?page=42891&category=1,46168,46171&abspage=1&ccurrency=3&SID=

[silentC]

You might need one of these too: http://www.leevalley.com/wood/page.asp?page=30126&category=1,46168,46180&abspage=1&ccurrency=3&SID=

[BigPop]

Thanks for that - dunno whay I couldn't get them to come up - everytime I searched all I got was the 1/4 " one

[silentC]

They've got two pages - one is 'Carbide Up-Cut Spiral Bit' and there's only the 1/4" job. The other page is 'Onsrud Spiral Router Bits', which is the one I gave you the link to. Don't worry, it took me a bit to find them too because I had no idea what Onsrud was (still don't).

[MrFixIt]

Hi

Re: round ends, I wonder.....

http://www.woodworkingtips.com/etips/2004/09/10/ws/
Yes, a good thought, but you would not get the correct radius on the ends. It would be a closer fit of course.

Ahhhh! Just been think about this. You *could* achieve the required radius by placing tennoned timber (wide) face down, with the edge of the tennon *directly* above the saw blade centreline, raise the blade to just touch (just miss) the face of the tennon and then "Roll" the timber over to the other face. This will whip off the corners leaving the round edge needed. That sounds like an opportunity for someone to design a jig. I'd love to do it but SWMBO says I have to finish my extension/renovation first, so it's over to you guys :D.

[echnidna]

Or you could find a gouge with a 3/8 internal diameter and use a HAND TOOL.

[echnidna]

I must be ill ... suggesting using a hand tool.
How do you use something without a switch....

[outback]

Well done Silent, I have Rockers plans as well, I have the tenon jig for use on a TS well on the way, then it's onto the mortice one.

They are both pretty simple ideas when you look at them, but allow for really accurate results.

[Grunt]

and use a HAND TOOL

What are hand tools?

[echnidna]

They are things you see in some museums or fanatics workshops

[silentC]

Hi

Yes, a good thought, but you would not get the correct radius on the ends. It would be a closer fit of course.

Ahhhh! Just been think about this. You *could* achieve the required radius by placing tennoned timber (wide) face down, with the edge of the tennon *directly* above the saw blade centreline, raise the blade to just touch (just miss) the face of the tennon and then "Roll" the timber over to the other face. This will whip off the corners leaving the round edge needed. That sounds like an opportunity for someone to design a jig. I'd love to do it but SWMBO says I have to finish my extension/renovation first, so it's over to you guys :D.
The Woodworking Tips article just gave me the bud of an idea. I was thinking of a bit of pipe with a slot cut along it's length so it can be slipped over the rail. The centre point of the pipe's radius has to be concentric with the centre point of the radius of the roundover on the tenon, or else you end up with the wrong shape.

Might be a lot of trouble for no real gain, since you can just do what Grunt suggested and cut a 45 degree chamfer. Might have a play on the weekend when I've finished cutting up banksia.

[MrFixIt]

Hi

The Woodworking Tips article just gave me the bud of an idea. I was thinking of a bit of pipe with a slot cut along it's length so it can be slipped over the rail. The centre point of the pipe's radius has to be concentric with the centre point of the radius of the roundover on the tenon, or else you end up with the wrong shape.

Yes, that could work, however you would not have compete control over the placement of the face. The (tennon) face could drop lower than the blade and be "trimmed".

If you take your idea a little further and "extend" the pipe sides, so that you end up with something like a hardbacked book with the middle pages missing. You would then slip the rail into the "book" the "book sides would be thick eough and flat enough too support the rail on the saw table and the "book" binding would be round enough for you to rotate the rail above the blade.

You could have this "adjustable" by inserting/removing shims to position the tennon edge at the concentric point required. (Of course you could make it very elaborate :D)


Might be a lot of trouble for no real gain, since you can just do what Grunt suggested and cut a 45 degree chamfer. Might have a play on the weekend when I've finished cutting up banksia.

True :D

[himzol]

Folks,

Can I ask a really stupid question about all this fuss about round ends. Why not just use a rasp after all who is going to see them once they are glued into place? :confused:

Or am I missing some point here ? (probably the one on my head)

Himzo.

[silentC]

It's just time consuming that's all. I've used all of the following methods:

1. Squaring the ends of the mortice
2. Rounding the tenons with a rasp
3. Rounding the tenons with a chisel

All are fiddly and time consuming compared to the process of cutting the mortices with the router. If there was a quick 'zing' way of doing it, you could get on with more interesting things.

Let's not start the 'journey more important than the destination' argument :)

[himzol]

If there was a quick 'zing' way of doing it,

Cool I'm all for that,


Let's not start the 'journey more important than the destination' argument

In order to do this I would need to know whether I was coming or going, mmmm Beer-oclock :)

[bitingmidge]

Let's not start the 'journey more important than the destination' argument :)

You just did!!

Why don't we ever get all misty-eyed at the thought of giving something a good old fashioned dose of the rasp?

Why is the humble rasp always found so much further down the food chain than the perfectly honed chisel with the shiny back?

Shave hairs? Pfffttt, girl stuff!! A rasp properly tuned will take the skin off an elbow!

BTW I understand that you can sharpen rasps by leaving them for a time in a bucket of hydrochloric acid...now that's SCARY sharp.

Cheers,

P :D

[echnidna]

Then you need to make a tenon jig that fits over the end so the cutter cuts the round edges of the tenon while they are being made.

[Rocker]

SilentC,

Your method of setting the jig is fair enough, if you don't have a dial gauge, but it means you have to mark the centre-line of the mortice on the workpiece, which is unnecessary, if you have a dial gauge. You can get dial gauges for about $30 from Bunnings, or US$13.95 from Lee Valley (if you don't mind working in Imperial). It seems to me that it is well worth while to get the dial gauge in order to exploit the full potential of the jig's capacity for precision.

BigPete,

The router is held against the fence by the bit rotation, assuming that you feed it in the correct direction. To use my jig, you stand on the same side as the wing-nut, and you then feed the router from right to left.

If you are ordering the 3/8" Onsrud bit from Lee Valley, remember to buy the 3/8" to 1/2" bushing adapter as well, since the shank of the bit is only 3/8".

Rocker

[craigb]

At the risk of making a complete @rse of myself, and in no way dissing Rocker's jig, what's wrong with just using the router table to cut your mortices?
Granted it's not going to be as super accurate as using a jig with a dial gauge, but shouldn't you be able to do repeatable mortices that are within + or - 1 mm of each other?

Craig

[BigPop]

Rocker,
I assumed that would be the case but it was just a thought I had when I actually was looking at Silent's pics. I have ordered the 3/8 to 1/2 bushing - as well as some bits.

[Rocker]

Craig,

I agree that it is feasible, with some considerable difficulty, to cut some mortices on a router table. However it is difficult to get accurate results, and in many cases, for instance when the workpiece is large or awkwardly shaped, it is impossible to do it safely. Also, in most cases, you could not safely cut a mortice in end-grain on a router table. The problem is that, on a router table, you have to move the workpiece to make the cut, instead of using the router's plunging capability.

If all you need to do is to cut four mortices on a face frame, you can probably get away with doing it on a router table at a pinch. However, if you want to cut a larger number of mortices, say for the back slats on the rails of a garden bench, then you really need a jig to do it effectively.

Rocker

[craigb]

Craig,

I agree that it is feasible, with some considerable difficulty, to cut some mortices on a router table. However it is difficult to get accurate results, and in many cases, for instance when the workpiece is large or awkwardly shaped, it is impossible to do it safely. Also, in most cases, you could not safely cut a mortice in end-grain on a router table. The problem is that, on a router table, you have to move the workpiece to make the cut, instead of using the router's plunging capability.

If all you need to do is to cut four mortices on a face frame, you can probably get away with doing it on a router table at a pinch. However, if you want to cut a larger number of mortices, say for the back slats on the rails of a garden bench, then you really need a jig to do it effectively.

Rocker

Yes IC what you mean. Thanks

[silentC]

... it means you have to mark the centre-line of the mortice on the workpiece ...
True but you only have to do it once on an offcut for the setup. Finding the centre line only takes a few seconds with a marking gauge. I find I get more accurate results if I leave the ruler in the draw :eek: The caliper only comes out to check the wall thickness.

Next time I'm in Sydney, I'll pick up a dial guage. They do sell them here but they must be made from gold judging by the price.

[outback]

Where's the best place in Sydney?
I asked at a couple of local places and they looked at me stranger than normal, and that's pretty dammed strange.

[MrFixIt]

Hi
Where's the best place in Sydney?
I asked at a couple of local places and they looked at me stranger than normal, and that's pretty dammed strange.A dial gauge is more of an engineering item than a woodworking item so you may need to go to a (metal) machine tool dealer. Carbatec in Perth now sells dial gauges, as they are also selling some small metal lathes and milling machines. If you stil have some difficulty, perhaps you could try Hare & Forbes.

http://www.hareandforbes.com.au/

[MarkV]

Here you go looks pretty cheap to me as you don't need the exxy stand


http://www.justtools.com.au/prod2191.htm

[outback]

Thanks guys, For that sort of money I reckon it would be worth getting one to make set up a bit easier and quicker.


Looks awful preefeshonarl too! :D

[Rocker]

The trouble with that one is that it only has a range of 10 mm; it is more convenient to have one with a 25 mm range, although, at a pinch, you can make do with the 10 mm one, using a 10 mm thick spacer.

Rocker