John15":14zvu7pk said:
Hi SPSlick,
I'm not sure about the in-feed and out-feed beds having to be parallel but at the cutter the in-feed should be slightly below the out-feed to avoid snipe.
Cheers,
John
Or perhaps not.
Beds: not co-planar but in parallel planes (exactly parallel).
Knives: _very_ slightly *above* the outfeed table, or level with it if you want to plane slowly. The reason was well explained by Steve Maskery in earlier threads on this: The knives cut a series of scoops in the wood as it passes them. To achieve a roughly planar surface (without snipe), the cusps left after the knives have scooped need to run on the outfield table. If the knives are below the plane of the outfield table you *will*, inevitably, get snipe (work the geometry out), as, once the end of the wood has been cut by the knives, it will start to lift on the outfeed table, and there will be an inevitable bump at that point. The planer also won't cut in a straight line, as the angle between the wood and the cutter block will change (depending on where you push down on it). You'll get a convex surface to the wood (slightly, end-to-end).
I've got a small 7" Kity. I have a really quick setup that works nicely:
- Whip off the fence.
- Put the knife in, with the clamp (the gib strip) loose, so the knife can move in/out against the springs easily.
- Put two clean pieces of 80g paper on top of the outfeed table, and the fence (which is aluminium) gently down flat on top of the paper, so that its end hangs out over the knife I'm adjusting. For best results it needs to be over the centre of the knife.
- Weight the fence down with something pretty heavy.
- Get the cutting edge of the knife 'top-dead-centre' on the block, held down by the end of the fence on top of it.
- Tighten up the gib strip (middle bolts first, then the outside ones).
- Repeat for the other knife.
Check the knives are both parallel to the outfeed table and projecting identically by using a flat-bottomed thin, straight batten either end of the knife. Lie it along the outfeed, projecting over the cutter. Turn by hand in the normal rotation. The knife should pick up the stick and move it towards the infeed table and drop it down again. The amount it moves is an indication of how much the blade is projecting. If it's the same both ends of the knife, it's parallel to the outfeed table. Same amount on both ends of both knives: both are projecting the same amount and are parallel.
On my Kity the distance moved is usually about 1/8" or 3/16" I'd guess this is OK for almost all planers, but theoretically it would vary with block diameter and how fast you push the stock over the cutter block.
I have a dial gauge, but really don't need to use it - this works quite well enough and it's very quick. If you don't get the results you want, change the thickenss of the paper under the fence. Anything smooth and flat will work instead, but the fence is handy!
E.