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Pocket holes?
I plan to build some pieces of practical furniture that does not need to look pretty.
As the
local FabLab is just next door, I have easy access to a Lamello milling cutter and other eqipment. Apart from dovel pins, these
"biscuit joiners" seems to be the prefered joining technique in Europe.
The preference in the US seem to be
pocket holes.
Now the strongest joint for particle boards is of cause to glue it. Since it is made of glued particles anyway, this maked it one solid pice.
But to glue something you need two things. alignment and pressure.
Lamello -type
Biscuit joiners provide great alignment and the limited ability to slightly correct that alignment in one axis but they need clamps for pressure.
Pocket holes provide no alightment but a lot of pressure.
So combining these two should allow me to build very strong furniture without having to use clamps and wait for effectively the next day for the glue to set because the screws in the pocket hole will clamp it down no matter where I take and put the unfinished piece.
After reading a lot about the topic, I decided against buying the cheap 30€ Wolfcraft Undercover Jig that is sold everywhere around here and get myself the big Kreg KregJig Master System in the current K5 version.
It's the big set. I just can't resist good tools. It's not the
real big one that has the drill built-in.
It was a good decision because
- the dust-collector is a godsent,
- the side-extensions (with storage space and easily available screw-size table on the inside) are very useful,
- having the lever on the side you are on make working with it a lot of fun. (As opposed to the older K4 version with the lever on the wrong side of that large piece of wood.)
The only downside was that the vacuum cleaner attachment had a different diameter then the auto-start/stopping Festool workshop vacuum cleaners we have in the local FabLab.
...but a few minutes of CAD and <40 0.5mm="" 3d="" a="" aesthetic="" br="" did="" for="" height="" layer="" me.="" minutes="" mm="" needs="" no="" not="" nozzle="" of="" part="" printing="" qualities="" stop="" that="" time="">
Festool vacuum cleaner adaptor
Results I
Obviously the first on I build was would be crap.
So I got myself some 1€ pieces of leftover material of the same type I wanted to use but wrong thickness and with a lot of defects and got working.
Without a plan I made some mistakes in judgement, some logical mistakes (forgot to subtract the thickness of the back wall,..) but not many mistakes in craftsmanship. Apart from working with too thin a material.
Access to proper tools made sure that the work was quick to do, quick to fix things and everything was square and how it was supposed to be.
Results I
So here I am, ready for a real piece of furniture that will actually be used. (In a place where nobody but me will ever see it.)
What I learned:
- Combining "Lamello" biscuit joiners and Pocket Holes is not worth the effort. Just skip the Lamello, meassure twice and double up on your clamps.
- You can not clamp down the K5 Master System onto a workbench.
- The dust collection is sow worth it.
- Use some kind of physical spacers for anything that needs to be clamped "in mid air" unless you have a second pair of arms.
- SPAX backpanel screws are stronger then the Kreg screws and they have a standard Pozidriv crossed slot. I would have prefered Torx here to have the screw on the driver and reach to a far away hole this way.
- You need to clamp down everything for fastening the 4.0x25mm or 4.0x30mm SPAX backpanel-screws in the pocket holes. They tend to bend onto the side with the hole with a LOT of force.
- The tiny Wolfcraft "ES 22" (3051000) are much stronger then they look.
- The Kreg clamps open up way too wide and are a pain to work with unless you have giant hands.
- The Kreg clamps are very strong but you need to adjust them first.
- Sawing melamin coated wood is hard without damaging the surface. I'll have to do more experiments here.
- You will want a very strong screwdriver with replacable batteries even for small projects such as this. Preferable 3 batteries and 2 chargers.
- While I only ever see pocket holes in solid woods, they works like a charm in particle board. Just limit your screwdriver to 8-10Nm to not outsight squash the board.
- Update: For Melamin-coated wood, pre-drilling through the pocket-hole makes sure the screw doesn't push the 2 pieces apart when threading inside the first part but not having penetrated the coating of the second one yet.
I had the chance to try the
Bosch Professional GSR 12V-15 FC screwdriver+cordless drill with replacable heads and I think it's the perfect tool for this. 20Nm is plenty. I can't use more then 10 without destroying the wood. The excenter+90° head combines reach into the back of cabinets and to screws close to a wall. I have not switched between drill and screwdriver yet but I imagine it to be a godsent for pocket holes.
Sadly there is no Sortimo L-Boxx for the Kreg. Only some Kreg case made for Husky Boxes.
So I will have to build that myself to combine both cases into one stack.
Update:
I asked SPAX about Torx backpanel screws because the Pozidriv bit can't hold on to the screw when reaching far into cabinets.
Sehr geehrter Herr Wolschon,
vielen Dank für das nette und freundliche Feedback. Es freut uns sehr, so etwas zu hören.
Die
Rückwandschrauben führen wir nur mit Pozidrive Antrieb, nicht mit Torx.
Der PZ-Kraftangriff ist vor allem bei der maschinellen
Verarbeitung besser geeignet.
Mit freundlichen Grüßen / with kind regards
i.A. Christoph Hessel, Dipl. Ing. (FH)
Product Manager
SPAX International GmbH & Co.
KG
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