I'm trying to cut some lap joints on a table saw using my stacked dado set. But the depth of the cut is inconsistent from pass to pass.
Here's a picture of what I'm getting:
It seems like I'm getting somewhere between 1/32" to 1/16" variation on each pass; it's difficult to tell for sure because the depth of the cut is potentially variable on each pass.
What could be causing this inconsistency?
Some things I've considered:
- Perhaps the saw blade is actually oscillating up and down as it makes the cuts. Is this a thing that happens in table saws sometimes? If so, what do I do to fix it?
- Maybe the wood is actually riding up over the blade? That doesn't make a lot of sense to me, as that is more like what happens in a climbing cut. I tried several things to get a more consistent joint, including making sure the pressure was as even as I could get it on each pass, and it helped a little but still had a lot of variation between passes.
- Maybe the board itself has inconsistencies in height, causing it to engage the cut at different angles? That doesn't make a lot of sense either, because the cuts seem fairly consistent through a single cut. They only seem to vary between cuts. But I did try planing the board before cutting the joint to see if that helped with consistency. It didn't seem to make any difference.
- Maybe my expectations are off and this is just what I should expect to get out of a stacked dado set?
At the end of the day, I have several questions that are all intertwined:
- This seems to be a lot more variation than I can use as-is in a lap joint. If I were to glue it up like this, my gut tells me I'd be compromising the strength of the joint. Is this true?
- What is causing this problem?
- How do I fix it?
LeeG suggested that accumulating sawdust might be the problem. I made several changes to my setup, and it seems to have done the trick. I replaced the fence I'd been using with a much straighter board, and I cut a rabbet at its base for dust relief. I made sure to keep the surface of the table saw as free from sawdust as I could between each pass. The changes seem to have worked. The cuts are much more consistent between passes now.