Help Using a planner/thicknesser

[ajmoore1]

Hi,

I have got a scheppach hms 2600ci and have just bought some 27mm waney edge oak boards to convert into tongue and groove boards. This is the first time i have attempted to prep my own timber.

The waney edge boards are 2.4m long but i only need them to be 1.7m when finished . I have staight edged the waney edge boards, and cut into 100mm(4inch) widths cutting all the sap wood off and cut to 1.8m length. If I place a 6ft straight edge along the flat(face) surface there is a bend in it of approx 10mm. When i plane the surface applying pressure on the outfeed table makes the board flat but when it is all planed up there is still approx 7mm bend in it. The boards are to clad a steel framed gate so will pull flat. Over a 6ft length is it what tolerance is acceptable ?

I am hoping to finish the boards to 21mm. I have bought 1/2 cubic m of european oak but don't want to waste it on planer turning it into sawdust!!!

Cheers

Jon

 

[9fingers]

You are not going to get them flat by planing and still end up with 21mm!
If there is a bow of 7mm then at best the thickness will have to come down by twice that amount.
At least this time you have a frame to pull it flat. Next time you need to be more choosy when selecting boards.
Did you get it from timports by any chance? They will let you select boards.

The steps I use are
1 cut to 100mm over length.
2 flatten the concave side on the jointer
3 Thickness opposite face to required thickness
4 joint one edge on the jointer
5 saw the other edge parallel, 2mm oversize
6 joint final edge to width.

hth

Bob

 

[coille]

Jon

I have freqently had to deal with bows of 10mm or so over 1.8m like you've got, and had to get a decent thickness out of the board. Be aware that you can alter the straightness of a board by removing a greater amount from one side than the other. Imagine I have a straight board 1.8m long which I have beautifully planed and thicknessed to say 25mm and it has stayed straight; but I need it 15mm for my job, so decide to shove it through the planer a number of times until it is down to 15mm. Brilliant, job done I say, then suddenly notice an awful bend in the timber - it has a bow down the length of the face of a good 7 or 8mm now - and the reason will be I planed all that 10mm off one face. I learned a long time ago that you need to take 5mm off of each face for the board to stay flat - its to do with the way a board dries and the tensions within the board. BUT - I also learned to apply this knowledge to straighten baords that were not straight as I was thicknessing them.

If you are lucky you may be able to use this to get your boards a bit straighter but you may not have enough thickness to play with. The board will bow towards the face you remove the timber from so if you lay the board flat and it is bent up in the centre of the board with the ends flat on the floor, that face facing up is the face you want to try and remove most off.

Good luck!

 

[joiner_sim]

When machining the thickness of the sawn board should be at least 6mm more than the finished thickness you want to achieve. Firstly work out how much of the board you will use, so cut to length leaving at least 100mm oversize. Then lets say it is a 450mm wide plank and as you said, you want 4 100mm wide boards. I wouldn't cut it down at all. I would surface the timber first, with the bow facing downwards on the planer. At this point you really only want to achieve at least a flat surface on the plank. A bit of rough sawn left on the planed side is fine, as long as it's enough to sit flat on the bed of the thicknesser. I then push thru the thicknesser the rough sawn side, getting a nice flat and clean surface, then I'd push thru the surfaced side to finish. Once the whole 450mm wide plank is at the required thickness, surface one edge, if there is a bow, you want to plane that edge first. Once you have a nice flat edge, cut on the table saw at 101.5mm (approx. other thicknessers maybe different, but the ones I have worked on have been best taking off 1.5mm in one pass). If you have a planer & thicknesser built into one, I'd then plane the edge you've just sawn and repeat until you have all the 4 boards you require, then setup the thicknesser to finish all the boards to 100mm wide in one go. Foran even better edge finish, if you have the timber available..... Saw at 103mm, thickness the sawn edge first at 101.5mm and then thickness the planed edge to your 100mm. I find that the thicknesser has a better finish than the surface planer.

That is the method I use and I have had some terrible planks in the past and have almost always been able to get them to finish up well. The timber I have mainly machined up was for kitchen face frames and the boards came in at around 28-30mm thick, finishing at 22mm.

EDIT: Also, a small note, you say you put pressure on the outfeed table, I'd of said pressure if put anywhere should be put on the infeed table. However, putting pressure on the timber to bend it to touch the cutters will not get a board flat. If the board is bowed, surface it first just pushing it, then turn it around and push it thru again, keeping turning it around. Downward pressure shouldn't be forced excessively.

 

[Chems]

When machining the thickness of the sawn board should be at least 6mm more than the finished thickness you want to achieve.

How can you attach a figure to this, or any of it, it depends on the board? If it has significant twist or bow its going to take however large the bow is. And sometimes with nice timber you only have to take a few cm off the end to be clear of checks and splits.

 

[joiner_sim]

Chems, that is the basis I worked on when planing up 2.4+ metre lengths and the stuff wasn't that good either.

 

[Chems]

I'd of said pressure if put anywhere should be put on the infeed table.

This is generally the opposite of what's said as well, being that the outfeed is your reference finished size?

 

[Chems]

When i plane the surface applying pressure on the outfeed table makes the board flat but when it is all planed up there is still approx 7mm bend in it.

As JoinerSim says, the pressure you apply should only be enough to keep the board in contact with the table, to much force and you will remove the bow, what you infact want to to is to take the end off the arc on both ends until the full board comes into contact. So that on your initial passes you hear contact with the cutters at the start of the cut and at the end and with each pass that contact should become longer until its flat.

For generally excellent all around advice have a watch of this:

http://thewoodwhisperer.com/episode-6-t ... rs-jumpin/