infinity plywood router bits too tight....

[chris fox]

I recently purchased a plywood router bit kit from Infinity, since these are slightly smaller than 3/4" plywood, etc. for a tight fit, my test piece is so tight that I need to use a mallet to fit into the dado. I didnt think these were supposed to be this tight, dosent sem likje theres enough play for glue?
I am using a A1 classic core veneer plywood and most of my other scape pieces from previous projects also fit this tight.

thanks
Chris

[Jim Becker]

The problem with trying to use so-called "plywood" router bits is that plywood varies in thickness, even within the same stack from the same manufacturer. This is why some folks will use a double pass with a smaller cutter so that the actual groove/dado/rebate is the exact size of the plywood that needs to fit into it.

[David Keller NC]

One really simple way to get around this problem is to make a router pass on the plywood piece that goes into the dado. If you do this on a router table with a top-mounted bearing on the rabbeting bit (that's actually on the table surface since the router's upside down), you're ensured that you've a perfect thickness for fitting a case together. It's an extra step, but it's sometimes worth it to avoid the aggravation of the pieces not fitting together.

[Orlando Gonzalez]

Measure the thickness of your plywood since they are not all of uniform thickness. The Infinity 3/4" plywood bits have a 23/32" diam. so if your piece is thicker than that you will get a tight fit. I assume you are using a router and a guide of some sort or a router table. Some solutions may be:

1 - sand one/both edge(s) until you get the fit you want.
2 - if you are using a RT then widen the cut in 1/64" increments until it fits. Do the same with your guide system if possible or maybe set it up to the thickness of the piece.

HTH
Orlando

[John Schreiber]

I recently used plywood which measured .704 on one corner and .670 on another. That's what they call "3/4" plywood.

[John Schreiber]

One really simple way to get around this problem is to make a router pass on the plywood piece that goes into the dado. If you do this on a router table with a top-mounted bearing on the rabbeting bit (that's actually on the table surface since the router's upside down), you're ensured that you've a perfect thickness for fitting a case together. It's an extra step, but it's sometimes worth it to avoid the aggravation of the pieces not fitting together.
Just to make sure I understand, the plywood is sliding on the table along the fence and the bearing is running against the plywood and above the bearing is the cutter?

Is it safe to have the wood trapped between the cutter and the table? It would seem that if the plywood isn't totally flat (and it's usually not) their would be a big prospect for kickback.

[Jeffrey Makiel]

Plywood thickness is getting thinner every year. I bet it will fit well next year, and probably be too loose the year after.

-Jeff :)

[Curt Harms]

though unlikely. It is still possible to get plywood that's actually 3/4". Not from the borgs however.

[chris fox]

I am routing on a table with clamp guide, my old Rockler table is too small so I am guiding the router. I changed out the plywood bit for a 3/4 straight flute bit and got a good fit with a slight gap.
I found an old sheet of WO veneer plywood and the plywood bit worked pretty well as far as fit.
I remembered seeing a tips/tricks in a recent FWW where someone suggested using plywood as a guide for exact thickness. I will have to find the article - I think Davids comments reflect this tip?

Thanks everyone..

[Rod Sheridan]

Imported plywood will be metric, since it's the most common measurement system.

Plywood manufactured in NA could either Metric or Imperial measure, depending upon what you've purchased.

Regards, Rod.