Veneer tearout issue

[hidrotule2001]

Hey all,

 

my humidor build recently suffered an unfortuante set-back when I was cutting the groove in the box sides to put the accent wood in(the boarder along which we cut to make the top), where I suffered some pretty decent tearout in the vaneer when making this cut with the dado-stack, and I was wondering if anyone had any similar issues or advice for a second attempt.

 

For context, I was using a zero-clearance insert I'd previously made for the dado stack(which wasn't exactly 0-clearance for this cut because it had been used previously, but there was very little unsupported area around the blades), and masked off the line I was using with blue tape prior to the cut.  These are fairly fresh dado blades(I wasn't using any chippers, just the two outer blades since it's only 1/4"), but ended up with sections of the veneer up to 1/4" or so being torn out along the cut, essentially ruining the vaneer face(this is quilted sapelee, so any sort of patching is going to show up, as far as I can tell).

 

My best guess as to the cause is that my clamping jig wasn't applying pressure correctly during the vaneer process, and so there were some unsupported pockets, or the fact that I was using Tightbond II rather than a dedicated vaneering adhesive contributed.  My only thought about trying to improve my chances beyond this is to try and score the vaneer along the cutting edges prior to running it over the dados, but if anyone else has any theories/advice, please feel free to chime in.

[Chris H]

Did the tear out occur on the face touching the table or the fence?  Did you bury the dado stack partially in a sacrificial fence?

[hidrotule2001]

Did the tear out occur on the face touching the table or the fence?  Did you bury the dado stack partially in a sacrificial fence?

 

The face touching the table; this was in the accent strip that's in the middle of the side faces(shouldn't have called it a rabbet, it's actually a groove )

[Trip]

I'm not building-along or watching the videos...

 

I've found the relevant video and quickly reviewed Marc's workflow...

 

One thing immediately comes to mind... To minimize tear-out in a veneer sandwich, you would need a very high-quality (and recently sharpened) dado stack.

 

If this was my project, I would have used a two-pass workflow -- more work, but would minimize tear-out: I'd have made all the shoulder cuts with a purpose-made veneer/laminate blade (offered by Freud, Forrest and others). With the shoulders cut, I'd then use a dado stack to hog-out the rest...

 

Just my 2c...

[Chris H]

1) What HHH said is a great option, but may be outside the budget.  

 

2) Another option to create a quick and dirty zero clearance insert.  You can lay some scrap plywood across the table top, if you don't want to take the time to make a true insert.  Just be sure to clamp it well.  Run a test strip and see if that eliminates the tear out.  

 

3) Finally, you can actually make the cuts with your normal table saw blade, in two passes.  You need to be sure your setup is flawless, but you can just "notch" out the edge by taking the first pass, and then flipping the box and cutting so the second pass is 90 degrees to the first one, intersecting each other.  Apply masking/blue tape over the corner after your first pass, before the second.  This will help keep the scrap piece from getting grabbed by the blade and tossed into you once it is cut free.  There is still a chance of kick back happening, so, take all your normal safety precautions.  

[hidrotule2001]

Thanks for the advice, I'll look at trying the option using the table-saw blade with some scrap I have left. 

 

I have some extra hard-board laying around to make another ZCI, which is probably a good idea anyway since this project has a good handful of 1/4 inch grooves/rabbets.