Baltic Birch MFT top: drilling, finishing, design and more - Need some guidance

[laura vianello]

Good morning, I have few questions for you and need some guidance.
1) I am making a new top for my work new built bench. It will be made of two piece 2'x4' 18 mm BB. When the workbench is not in use, the two pieces with be on top of each other: one finished and clean and the other one underneath with 20mm MFT holes (I bought a PARF guide and LOVE IT and this is my second top). My plan is to flip the top 180 degrees, support it with some wing brackets (for a better term) and used the clean panel as a work desk and the one with MFT holes for my hobby when I have time. However, I would prefer to open the tops and realigned them perfectly in the center of the workbench, basically having a 4'x4' top centered on top of a 2x4 workbench. I need to figure out a way to lock it. That would save me some time and I will not have to see the ugly brackets. Note: as you can see from the workbench pic on the left side, I build a panel that cover the drawers, so dust from the MFT work will not sip through the drawers. I build the same thing on the right but I have no pictures.

My questions are:
1) Is there any trick to drill 20 mm holes with a forstner bit without tear outs? I do oil the bit every hole, the drill depth is the depth of the wood (should it be slight more or less?). I did a small top already and even though I put a sacrificial 1/4 ply under it while drilling, I still had tear outs at the bottom.
2) Would the tear out improves if I poly 3 coats on the bottom before I drill? I did it only once and it did not seem to make any difference
3) I was thinking that I do not really need Poly on the top of the "MFT top" but I still need some sort of finishing to avoid glue up messes/cleanups. I applied a coat of Sanding Sealer already and I stopped. May I put wax on it without using Poly?
4) Hardware for flipping the top: I thought that sewing hinges would fit the purpose of flipping the top panel 180 degrees, being sturdy enough for BB, not being TOO visible when the top panel is resting on the MFT. I have attached a pic of them. Any suggestion for a better way?

I would love to hear your suggestion if you have done a similar project. It is my second project and I am learning as I go. Your help is really appreciated!

[John Blazy]

Trick to drilling clean holes is sharp spurred bits (Forstner has edge spurs, but also newer spade bits and brad point), and high speed, then flip board over once the center pierces through, then align with center pierced hole, then drill through. Sharp bit, with hih speed, and skill to not go through bottom quickly also works. I drill clean holes all the time without flipping over, because my bits are sharp (I use a diamond hone to dress them) and I slow down feed rate right when piercing, and use high RPM.

Center point on Forstner bits are pretty short, which makes them difficult, so I would use a spade bit with edge spurs and do the flip over trick.

[Reinis Kanders]

Try using masking tape on the exit side.

[Sean Tracey]

Use a piece of MDF underneath to prevent tearout. You could make a jig that aligns with existing holes so the same piece can be used over and over again.

[laura vianello]

Sean, I actually bought a hardboard panel and I was planning to use it exactly the way you are suggesting. Thanks!!

[laura vianello]

John, The PARF guide comes with a Forstner bit not a spade bit. It has a pretty long tip (more than 1/8 I think). Tolerances are very important, so I will have to use the guide and its bit. I thought that RPM with Fosrtner bit has to be very low, now I am confused. Thanks

[Bohdan Drozdowskyj]

Use the Parf drill, without the guides, to break the surface, go thru the first layer, on the back after you do the 3 mm holes. Then flip the sheet and finish drilling from the top. This will give you perfect holes with no breakout and no special techniques required.