Smoking Router Bit

[Tom Cooney]

Hi Folks,

I'm having problems making box jointed kitchen drawers on the router table. The shop is pretty smoky after even one drawer and the sides of the cut are scorched. It's a new 1/2" bit and I'm using 1/2" ply. Am I using the wrong kind of bit?

I picked up a spiral router bit from Lee Valley http://www.leevalley.com/US/wood/page.aspx?p=42891&cat=1,46168,46171&ap=1

[Philip Rodriquez]

That is a good bit and if it is new and sharp... the following may be the issue:

A slow feed rate
Slow router speed (should be set to your max)
Material

Does the bit have burn marks? If so, try and clean it.

[Jeff Monson]

For box joints, I have my best luck on the tablesaw, dado blade and a simple box cut jig.

A downcut bit may work better if you prefer to use the router table for this application.

[Bill Huber]

Is the bit ok, could it be a bad bit, it happens sometimes. Is the edges sharp and new looking.

I use a bit like that from Eagle and have no problems with box joints on the router table.

If the bit is ok then I would say it has to do with the speed of the cut, try speeding the feed rate up and see if that helps

[David Hostetler]

I had a dud straight cut bit from Rockler a while back that would smoke like crazy. Looked and the edge was about as dull as my Art History professor from college... (Nice guy, and a great teacher when you got him AWAY from the lectures, but his lectures could cure the worst insomniac...)

Mind you, plywood, with all of its glue will tend to smoke and smear a little bit, especially if the bit is spinning too slow. Like was mentioned above, check that...

#1. Bit is sharp, with no wax, cosmoline, whatever protectant it shipped with on it.
#2. Bit is STRAIGHT. Even the best brands ship bent bits from time to time.
#3. Router is set to full speed...

[Brian Kent]

I hate smoking router bits. They cut my lips.

[glenn bradley]

Not clear if the bit is HSS or carbide.

- As others have said, my first guess is speed, router should be around 20,000 RPM, feed rate should be "medium"; not too cautious but not reckless either.
- HSS burns easier that carbide in my limited experience with HSS. I did use a 3/4" HSS bit for dog holes and would give it time to cool off every 2 holes or so. Still some burning.
- The glues in ply and other materials will burn more than plain wood but, the amount of smoke you mention is excessive.

[Tom Walz]

In the industrial world plywood is often considered as being highly different than wood.

The first difference is the glue. As referenced above the glue is sticky and gets very sticky as it gets warm.

The second difference is that the glue contains materials to extend it or stretch it out. So you have the actual glue and then you have something added to it that is usually particulate and thus abrasive. This is added to make the glue spread further and save money.

The third difference between plywood and wood is that it plywood has the grains going opposite directions. Thus you are always cutting both with the grain against the grain.

The fourth difference is that plywood is made of very, very thin sheets of material and thus more prone to splintering than solid wood. If you have ever been in a plywood plant you will see that the plies require very careful handling or they will split apart on their own.

The fifth difference is that plywood is a very heavily processed material. The plies are made of wood that is been peeled from the log and this creates certain stresses and tears in the materials. In the materials are further compressed and stressed during the assembly.

Also a lot of plywood is coming from China which has its own unique problems.

All in all there are real valid reasons to use tools specially made for plywood rather than trying to use standard woodworking tools for plywood.

[Glen Blanchard]

I hate smoking router bits. They cut my lips.

Pa Dum Pum. Brian will be here all week friends!

[Rod Sheridan]

If you purchased the HSS bit it's only suitable for use in solid wood.

The carbide bit should be fine if your speed and feed rate are correct.

Regards, Rod.

[John Gregory]

That is funny Brian.


I hate smoking router bits. They cut my lips.