Edge planing with a P/T

[Ratter]

I'm sure this is one of those things that just needs some logical thought ....

I'm making panels for kitchen doors from oak and they about 8-9mm thick. When I plane up the edges of the pieces for glueing, it seems to be a rather hit and miss process. Either the edges don't meet in the middle or at the ends and now I'm onto the larger panels and getting frustrated.

So, what's the best technique - do I press on the infeed table or the outfeed table or a mixture of both?

Is it possible I haven't got my blades adjusted correctly.

My machine is an Electra Beckum HC260M, one of the older green ones.

 

[Digit]

First step is to check that the infeed and outfeed tables are horizontal to each other. Wind the infeed table up/down till it is a few thou lower than the outfeed then place a good straight edge on the outfeed table and check that there is the same 'daylight' under the straight edge along the infeed table.
Do this close to the fence, in the centre and away from the fence.
I have known cases where the tables are hollow/crowned and misaligned across their width
If there is no significant error either the knives are incorrectly set or your technique is suspect, but untill you have checked the tables there is not much point in worrying about either of those alternatives.

Roy.

 

[OPJ]

A slight gap in the centre of a join between two boards is actually considered a good thing, provided it's no more than, say, 0.5mm.

To straighten a convex edge on a planer though, is actually quite tricky to do, without creating a slight taper across the width of the board. I reckon you'd be better off putting it in the vice and taking a few 'stopped shavings' from the centre with a plane until the two ends can rest firmly (without rocking) on the bed of your machine.

 

[JoinerySolutions]

A slight gap in the centre of a join between two boards is actually considered a good thing, provided it's no more than, say, 0.5mm.

To straighten a convex edge on a planer though, is actually quite tricky to do, without creating a slight taper across the width of the board. I reckon you'd be better off putting it in the vice and taking a few 'stopped shavings' from the centre with a plane until the two ends can rest firmly (without rocking) on the bed of your machine.

Not so! It used to be the practice back in the day when animal hide glue was the main adhesive and then only for long boards(in excess of 5/6 feet) This topic has been covered before, but myth keeps popping up.

As digit posted, check the tables and the knives for correct adjustment, pressure should be even across both tables, correct planing requires one to hand 'walk' the timber so that as soon as the timber is referenced on the out feed table you continuously maintain pressure on both tables.
The method is to switch hands on top of the timber so that constant down force is placed while never having a hand directly over the cutter block.
It is the safest way.

If your timber is bowed to start with make a couple of passes a short way in from either end, then a test full pass and check the result. It is a practice learnt thing but you will soon be able to eye down a board and just know the best approach, as long as the machine is set up right. :wink:

 

[devonwoody]

My comment is to practice with some scrap or waste timber re the guide pressure you apply when using the planer, I found there is a critical point when I switch my weight to the far end to get good finish.

 

[woodbloke]

A slight gap in the centre of a join between two boards is actually considered a good thing, provided it's no more than, say, 0.5mm.

I agree with Olly here, though a gap of .5mm is far too much. Conventional wisdom used to recommend the thickness of a fag paper in the middle 'twixt two boards, both end are then in compression as the joint is tightened. Convex boards are definitely not needed as there's a danger of the joint springing at the end. Dead flat also works of course - Rob

 

[Ratter]

It turned out that the outfeed table was quite a bit out.

Less than a quarter turn on the adjuster screws has made a big difference. It also sounds right now and you can also feel that you are getting an even cut

Thanks for all the replies.

 

[Digit]

Like many things my friend, easy when you know how! :lol:
Next point, they often need regular checks as well, especially if mobile.

Roy.

 

[Digit]

At the start I made the point of checking the machine first. Me and my big mouth!
I installed the new cutter bar that I made into my thicknesser, set the knives using my home made setting jigs then 'clocked' them for accuracy.
Both parallel but one higher than the other by 3 thou.
That will do for now so now to set the cutter block level with the base. The machine is a Metabo 330 which has a chrome base plate on the alli casting, the chain that drives the rise and fall has a fixed sprocket on one end and an adjustable sprocket on the other, so I checked the level of the cutter block by winding it down on to a piece of wood.
When it touched I attempted to slide the piece of wood to the opposite end of the block. No way?
So I released the adjustable sprocket and raised that end of the block.
No joy!
About an hour later light began to dawn. I removed the chrome base plate and the damned thing is high in the centre!

Roy.