Pocket hole problems

[potato80]

Hi folks.

Just practicing with pocket holes (in preparation for making some cabinets for wardrobes). Using the Trend system.

Two questions:

1. Why does my wood split (see picture)? Am I simply drilling too far in, is it the screws, wood itself, or set up that's causing the issue?

2. When I feel I've drilled the screws in far enough, it seems to push the wood a mm or two past the edge of the piece I'm attaching it to.

Any advice much appreciated! The system seems to work really well in everyone's videos on YouTube!

 

[foxhole]

Probably wrong screw type , size , you can buy flat head screw designed to prevent screw travelling too far into timber . Timber will be pushed if there is no pilot hole ( you can tighten then release screw and tighten again which will avoid the push.)

 

[Deleted member 174758]

Pocket hole joining was originally developed for dofteood, plywood and "melamine" (MFC - melamine faced chipboard) and NOT MDF. The reason the MDF is splitting is that the pilot hole is too small and/or the screws are too big or the wrong type, a Foxhole says. MDF requires the pilot hole to be properly cleaned out and very much nearer the actual size of the screw than either wood or softwood to avoid splitting. Movement can be countered by setting up a corner cramp or using the special cramps sold by Kreg

Personally I find the joints made by this system in MDF and MFC to be incredibly weak and subject to bursting if the item is subjected to any adverse loading (e.g full height wardrobe being moved upstairs and manhandled into position)

 

[potato80]

Really helpful. Thanks so much!

 

[foxhole]

Mdf needs pilot holes and no closer than 80-90mm from edge so your mdf dimensions make it impossible to screw together , glue or internal brackets might work what is the project ?

 

[potato80]

Mdf needs pilot holes and no closer than 80-90mm from edge so your mdf dimensions make it impossible to screw together , glue or internal brackets might work what is the project ?

These were just small test pieces, so I could practice. I'm making a set of floor-to-ceiling wardrobes. Probably 18mm MDF (though reconsidering, based on the above info), placed on top of a ladder frame, and fixed to batons on the three walls. I'm buying the doors ready-made.

 

[foxhole]

You can make with 18mm mdf but screw thru sides staying 90mm from edges and 120mm apart. Pocket jig of no use for that project .
You don’t need a frame .I made a shallow cupboard for my landing (just 320mm deep)to house towels etc. Mdf doors routed to look like panels .You can strengthen joints with plastic blocks and also use to install Shelving .

 

[Deleted member 174758]

Agreed. If you make your carcass with the top and bottom inside the two "gable ends" you simply need to pilot drill and countersink the holes then screw together, ideally using black carcass screws. Fairly standard way to produce carcasding used in shop fitting where the screw heads won't be seen
Cheap, too

 

[potato80]

Cheers that's helpful.
I want a ladder frame beneath the units, so I can have seamless skirting running around the room Inc the wardrobes (which will also mirror the seamless coving running around the room and at the top of the wardrobe, too).

I'll forgo the pocket holes. Much simpler!

 

[Deleted member 174758]

Ladder frame deffo the best way to level up for the base. Use horseshoe packers to level it all up and fix down to the floor with screws