Router Table Bit Problem

Re: Router Table Bit Problem

TJD Edmonton

Are you using an upcut spiral bit? That is what happens when you use a straight bit.

Re: Router Table Bit Problem

Dave Bair

Make the first pass with a 1/4" bit.

Re: Router Table Bit Problem

Barry Irby

Stuart, I have read your comment about a half dozen tiems and don't see what is causing your difficulty. I have done many dadoes and sliding dovetails and have not had the problem. Mine are generally wider (3/4") and deeper, maybe 1/2" and the bits are sharp. I generally route a path right down the center with a straight bit, sometimes an up cutting spiral about 3/8" sometimes a 1/2". The first pass cuts away the bulk of the wood, taking some of the load off the dovetail bit and leaving a path for the chips to escape. Usually do this on a router table without dust collection. The wood is dry, acclimated to the shop, but air dried.

Sometimes do it with a router with a guide bushing and a home made dado jig. When I do, I use two routers, one straight bit and the other dovetail.

Just babbling on here, trying to imagine what we do differently.

Re: Router Table Bit Problem

Keith Newton

Stewart, I’ve got a project coming up where I’ll be needing to cut tapered sliding dovetails on the ends of a 20’ L x 8.5’ bookshelves. As far as I know, I don’t think there is an upcut spiral dovetail bit, so I will be jigging up to use two routers. One will be a straight upcut, followed by the dovetail using the same template while it is set.

One thing I’ve found in the past, is to take care to sand or cut the raised or bent up fiber along the edge of the slot made by the first pass. If not, it raises the router base off the wood a little, this will then cause the joint to be out of tolerance.

On smaller parts than I’ll be using on this upcoming projects, I usually make the first rough out cut with a dado blade on the TS which is a lot faster especially if there are lots to cut.

Something else that just occurred to me that you didn’t ask about, but I’ll be trying is the amount of taper from front to back. In the past, I’ve normally just chosen something like 1/16”-1/8” arbitrarily. However, in thinking about it, each time you double the front to back taper, you half the distance of starting to squeeze, before it stops sliding any further. I’m starting to like the idea of going wider. Do any of you have experience with this? What about you mathematicians, what say ye?

Keith, I'm trying to remember

Barry Irby

It's been a long time since I did tapered sliding dovetails.

When I did them I made a jig to use with the router with a guide bush and the slot in the jig was tapered, but very slightly, maybe 1/100". When I did the matching piece on the router table, I used the same bit set to a matching height of very slightly less and to account of the taper I put a piece or two of blue tape on one or both sides of lead end of the board.

Since I was routing both sides of the shelf the set up was a little fiddly but once you got, you're good to go.

The very slight taper was amazing. The pieces "fell" in about 90% of the way and a bump with your hand or a rubber mallet sent the home. They locked up, very had to get apart.

I had not considered using a steeper angle, thanks for the suggestion.

I often glued mine with epoxy because it acts like grease and has a long open time and does not swell the wood. A few I glued with Titebond swelled and were a sumbitch to drive home.

Now that I think about it, wonder how hard it would be to make them straight on one side and dovetail on the other?

Re: Router Table Bit Problem

Stuart Johnson

The sliding dovetails were stopped not tapered using a 3/8 dovetail bit 3/16 inch deep. The dados were using 3/8 straight bit also 3/16 inch deep. I understand about using a straight bit first on the dovetail but at 3/16 I didn't see the need. I'm done with this part of my project now but will keep working on the issue until I find a solution.

Stuart....

Barry Irby

I am still ciphering on why you have this problem and generally I don't.

Is the hole in the base of your router small? Could it be the base plate is capturing the dust and causing it to pack up underneath?

Re: Stuart....

Stuart Johnson

That could be it. I'm using a plate that just fits the bit. I'll try one with a larger hole.

Re: Stuart....

Barry Irby

Try that and let us know. The shavings have to have somewhere to go. I am betting you are trapping and compressing them under the base plate.

I am anxious to hear.

Re: Dado Bit Test

Stuart Johnson

Here are the results. With just one set of test it does look like the chips jammed. They wasn't much difference between the largest plate and the next smaller. The one that just fit the bit clogged solid. I have just received a Incra router dust box but haven't had time to install it yet. Once I do it will be interesting to see the same results.

Re: Dado Bit Test

Barry Irby

There you go! I think you found it. Try the larger hole in the base plate and some suction and I think it will be even better. Actually, I think what you have now is "good enough" so if it gets a little better it will be great.