Noob Parf MK II drilling question

[MikeyBikey007]

I'm building two small Paulk Smart Benches approximately 2'x4' with MFT-style tops.  I'm going to use the Parf MKII system to drill the holes.  I stacked, aligned, and screwed the two tops together to drilled all the 3mm holes.  It turned out to be a 6 x 12 grid of holes with the 96 mm vertical and horizontal spacing.  I'm getting ready to drill the 20mm holes and was wondering if anyone had drilled two tops while still stacked and screwed together.  I can see the time efficiency as a real plus but I was wondering if there are any negatives that I might be missing.  It looks like the standard UJK 20mm Forstner bit will be long enough.  I was going to pre-drill the underside to reduce any blowout.  I'll make sure to go slow and clean out the hole to reduce any heat build up.  Any other thoughts or concerns from the collective before I start drilling.

 

[MikeGE]

I don't know why it won't work, but make sure you drill the 3mm pilot holes completely through both tops.  The center spike in the 20mm cutter does not cut and is only a guide.

 

[MikeyBikey007]

I don't know why it won't work, but make sure you drill the 3mm pilot holes completely through both tops.  The center spike in the 20mm cutter does not cut and is only a guide.

I have drilled 3mm holes through both tops.  My next step is to pre-drill the underside to reduce blowout and then drill through the two tops. I saw this process in one of the New Britt Workshop Parf Youtube videos.

 

[Packard]

I don't know why it won't work, but make sure you drill the 3mm pilot holes completely through both tops.  The center spike in the 20mm cutter does not cut and is only a guide.

I have drilled 3mm holes through both tops.  My next step is to pre-drill the underside to reduce blowout and then drill through the two tops. I saw this process in one of the New Britt Workshop Parf Youtube videos.

When I drilled my MFT style top, I put a piece of scrap underneath to prevent blowout.  That worked well too.  Of course I trashed several strips of MDF doin so, so pre-drilling the underside might make more sense.  I was using an auger style bit and that won’t work for partially drilled holes.

 

[njt1000]

I have my MFT too on top of two 4x2 across two saw horses. I keep the mft in place with 20mm holes drilled through the top and into the 4x2 and drop in long benchdogs.

I drilled through in one go no issue. Just keep pecking up and down to clear the debris.

 

[smorgasbord]

In this video from The Woodgrafter, he uses dogs that fit into the underside groove of the track to have a cut line that doesn't go through a set of dog holes:=ZI2rc-03eQuG6YD5&t=503

(Start at 8:23 in if the full link doesn't work)

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