19 February 2010

Slippage and carry forward

Don't you just hate it when stuff doesn't go to plan? I was in the 'shop the other day passing some lumps of oak across the surface table of the planer, ready for slicing up into veneer. As I was merrily pushing timber across the top, it was planing off one side only, so that after a few passes, the end section of the timber looked distinctly triangular. I kept on going thinking that it was me, but the problem only got worse...strange and peculiar?

After a bit of head scratching, I found out what the problem was and on this occasion, it weren't my fault (honest 'guv!)

The blades had slipped down just a fraction below the outfeed table so there was no 'carry forward'...


That meant that I'd have to hoick them out, sharpen them on the Tormek planer blade jig and reset them, which is what I've been doing for the last couple of hours. On some planer-thicknessers this is a relatively straight forward job, but on my Kity439 it takes me at least an hour to set both blades. The tension on the retaining block bolts should just hold each blade so that minute adjustments can be made and after umpteen attempts this ought to give a 'carry forward' of about 3mm...and then when it is finally right, instead of tightening, like an eejit I undo the bolts so that the blades leap up and the whole bloody thing's got to be done again!

It's a 24 carat, genuine pain in the arris which is probably why I don't do it very often.

1 comment:

Olly Parry-Jones said...

That's one chore I absolutely loathe - changing the planer blades! I've even tried those magnetic jigs but the results are just as variable as if you were to use another method. It often takes me at least one hour to do all three knives - I honestly think I'd enjoy that time more if I was constantly removing and refitting the same bandsaw blade!! ;-D

The trouble with planer/thicknessers is that, even on a good one (Scheppach), you'll find the tables move out of alignment over time. I used to obsess over these kind of things but I've since realised it rarely matters (my thicknesser bed isn't parallel to the cutter block, anyway).

I used to set my outfeed so the knives would carry a block forward by 3mm, and I would get snipe. At 2mm, it would be fine. I checked yesterday and it was averaging 6mm, but not leaving any snipe?!? Go figure! :-D