What is wrong with my sliding dovetail???

[I_wanna_Shed]

Hello all,

I've spent a few hours in the shed today tryng to do what I thought would be a simple joint - a sliding dovetail. It should just be a case of route the dovetail trench, move the fence out to the correct distance, then route the end sides of each shelf, keeping the dovetail bit at the same height.

But nooooooooooo...........! As you can see in the attached diagram, my pin looks like it is at the correct angle, but it is just too long (a gap between the side and the shelf, this is about 1.5mm). I tried lowering the bit when I routed the pins, but of course this just made the pins too wide.

The bit I am using is just in a $40 16 piece router bit set, but I thought as long as you keep the bit height the same, it should all work out, no matter what size/angle the bit is.

This is being done on a Triton router table. Any suggestions from anyone on how to fix this would be greatly appreciated!

Cheers,
Nathan.

[NewLou]

Gidday

Personally the first thing I would try is to handplane down your tail so that it seats without the small gap.

Its critical that you mill the joint as precisely as possible n with out a great jig is a pure lesson in accuracy and patience.................... A tough joint to freehand rout by any stretch of the imagination.

For me Sliding dovies are one of the hardest joints to master but perhaps one of the most elegant if you can get the tails n pins to m8 exactly.

If your after some X pert demos on how to pull of this joint without any expensive or complicated joinery machines or jigs check out the following videos (Available from taunton press):

The versatile router with pat warner
Router joinery with gary rogowski

I recently did some Sliding dovies in a small weekend project I completed a week or so ago but I had my Woodrat to help me which excells at sliding dovies

REgards Lou:)

[Schtoo]

Is the joint a tight fit, other than that gap?

What I mean is does the tail slide into the socket with resistance, or does it rattle in?

If it rattles in, then you have set the fence to cut too deep and should have a gap underneath the tail too.

If it slides in with resistance, then it's possible that the bit has moved in the collet and completely blown the joint.

Lou, all the fancy gear, books and videos are not likely to help in this case. I think Nathan has the gist of it, being you don't touch the depth setting once you start cutting. That's the single most critical part of sliding dovetails, all other things you can tweak in and out, so long as you don't fool with the depth setting.


Anyways, make sure the bit is tight (but not over tight) in the collet, do NOT touch the depth once you cut the socket and tweak the fit with fence adjustments on the tail board. They are dead easy, once you work out how to do them with what you have. ;)

[Bob Willson]

What Schtoo said.

[Des.K.]

Hi Nathan,

I've had pretty much the same results for sliding dovetails on the Triton router table. While I'm a big fan of the router table, I think the problem in my case, and also probably in yours, is that it's not perfectly flat. You're running an edge then a face over the table, and they extend over different areas. Unless those areas (along the length of the table next to the fence, and across the table over the sides) are in a perfect plane, the bit will cut to varying depths. (I hope I've made myself clear).

In Gary Rogowski's video (an excellent DVD and well worth the money), all he does is clamp a melamite(?) board to the edge of his bench, and fit his router to that. Perfectly flat, so no variation on the depth of cut.

I don't think there are is any simple way to correct the gap with your joint, other than plane the ends, then glue thin wedges to fill in the side gaps that will open up. Certainly not a clean joint, but depending on how you fit the wedges, not overly ugly. Others may have better ideas.

Regards
Des

[JDarvall]

You doing this on the router table ? ....Same bit used to cut the female and male parts ?

The girly part,,,the pins,,,,or the trench as you call it not deep enough....

If its off a table, first guess, is your not running the board flush to the table top properly.....or....maybe more likely if your not using a table and just dropping the router over the top, the depth setting on your routers creeped between cutting the trench and doing the manly bit.

Yep so thats my wild guess,,,,check the knobby thing that fixes the depth setting. Is it tight enough ...the springs on the router shaft could be shifting the depth. Or you've bumped it ya cluts !

Goodluck.

[Bodgy]

Another possibility, that has happened a few times to me, is that maybe the bit slipped down a little in the collet, like Schtoo said

If the collet nut is not really firmly tightened it happens.

Probable cause, non level table or cupped/ bowed stock

[I_wanna_Shed]

Thanks Schtoo & Des.K,<o></o>
<o></o>
The tail does slide tightly into the groove, and fits nice and snug and infact looks very good, its just that the dovetail 'tongue' is too long, and continues to taper down further than it should (like in the diagram in the 1^st post). Thinking about it all morning, the angle of the dovetail is fine, it just needs to be longer (ie, higher bit). But<o></o> I’ve measured the router bit with a height gauge before and after each cut, and it is the same height.

So this leaves one option as far as I can see.....<o></o> I’ll get back into the shed after work and continue playing, perhaps like Des.K said, it may just be due to the Triton table - maybe the stock is dipping down slightly as it passes over the bit. The table is relatively new so I’m not ready to upgrade yet, so would like to get it going well! All in all, the sliding dovetail joint looks brilliant, and should be very easy to do!<o></o>
<o></o>
Thanks everyone, I’ll let ya know how it goes.<o></o>
<o></o>
Cheers,<o></o>
Nathan.<o></o>

[Template Tom]

Sorry I cannot assist with the idea of the cutter in the router table but I was demonstrating that very same joint at the WA wood show last weekend only I was using the plunge mode and I must confess I did produce a good tight fitting joint i will try and post a pic of the results.
Tom

[Skew ChiDAMN!!]

I’ll get back into the shed after work and continue playing, perhaps like Des.K said, it may just be due to the Triton table - maybe the stock is dipping down slightly as it passes over the bit.

Ahhh... A new Triton! That may be your problem. I'm not belittling the Triton, mind you, but I had a similar problem when mine was new too. All those many years ago and I still remember... :rolleyes:

It could be the inserts' fault. Try putting a square edge across the table/insert and double check that the insert's not sitting a little proud. In my case it was and when I ran the flat of a board through the board was lifted off the table by just that li'l fraction. Then when I ran the edge of the board through, because it had a smaller footprint the insert depressed downwards a wee tad further, even though I was using the same downward pressure!

At first I removed the insert, which I don't recommend, and tried a few test cuts. That fixed my problem, so I knew 'twas the inserts fault... but without it one tends to get the routers version of snipe, esp. with short lengths. So I took to the top of mine with a belt sander. Holding the insert in a vice, not the table! ;)

Later, I replaced it with a home-made version. Hope this helps... at the least it'll give you one possibility to rule out.

[Template Tom]

Sorry I cannot assist with the idea of the cutter in the router table but I was demonstrating that very same joint at the WA wood show last weekend only I was using the plunge mode and I must confess I did produce a good tight fitting joint i will try and post a pic of the results.
Tom

Actual pic

[I_wanna_Shed]

It could be the inserts' fault. Try putting a square edge across the table/insert and double check that the insert's not sitting a little proud. In my case it was and when I ran the flat of a board through the board was lifted off the table by just that li'l fraction. Then when I ran the edge of the board through, because it had a smaller footprint the insert depressed downwards a wee tad further, even though I was using the same downward pressure!

I only had a chance this arvo to do a quick check on the levelness of the table, insert and clearance bit. It is close, but not perfect, and there is slight 'bounce' in the zero clearance bit.

I'm thinking of doing the stainless steel table top mod as on the Triton Woodworker's site: http://www.tritonwoodworkers.org.au/

It would be a pity to cover up the orange ;), but has anyone done this and have any advice or feedback to pass on?

Cheers again,
Nathan.

[Skew ChiDAMN!!]

I made similar, based on the Triton mod but using 6mm MDF instead of SSteel. Lack of funds (and suitable tools) dontcha know?

I decided I didn't like the zero-clearance insert idea for small bits so made three tops, one for panel bits, one for ½"-1" bits and one for the li'l piddlers. I think the SS would be better, as I ran into minor hassles putting the fence back in place. Near the end of the thread, etc, etc. Nothing serious, just annoyances.

The worst of it is that I haven't done any serious routing for quite some time now and had an MDF shortage a while back so my tops were... "resurrected" as something else. :o Now I'll have to make 'em all over again, but that can wait until the need is on me. ;)