Wednesday, October 28, 2009

FWW's Planer Sled Notes

Awhile ago, I built the planer sled shown in this video on Fine Woodworking's online site: Keith Rust's Planer Sled.  I don't have access to the article so some of the observations below may have appeared in the article.

Voilà, my sled:

The first difference you'll notice is that I didn't use bungee cords to hold the levelers in place (my term for them).  Rather, they are in a box.  You'll see why later.

The base is a torsion box that I took care to make flat.  Turns out there is a slight variance over the whole length, but not too bad.

My levelers actually look a lot like Keith's including the bungee slot I decided against.  In my case, I put a fence near the back for the victim board to register against and prevent movement.  It is only 5/16" taller than the levelers.

The tape on the top of the levelers and the bottom of the wedges is 3M's safety tape.  Very sticky and very consistent grit; available at a borg near you.  Cheaper stuff at Harbor Freight was very inconsistent, which concerned me.

I drew a red mark on one side of the levelers.  Note the direction of the wedges.  When placing a board on the sled, I want all the red lines facing away from the back fence.  In this way, if the board moves a very little backwards during the planing operation (or after shuttling it back and forth for repeated passes), the planer will be pushing the leveler into the wedge tightening it rather than loosening it.  I didn't think of this ahead of time.  On my first trial board, it became an issue and thus the red pen pulled out.

The first board I had to run through had an evil twist/cup combination.  Normally you'd run a board through cup-down, but with the twist, I had places where I needed support for cup-up meaning support on the outside edges, but since it dipped down in the middle, there was no room for the full length of a leveler.  Follow that?!  So, I made a batch of "half-levelers" that I can put on any spot.  The portion that faces down (leftmost tape in this picture) is gently planed so as the far side is raised with the wedge, there is always flat contact somewhere along the tape.  The portion that faces up (rightmost tape in picture) is gently rounded so it, too, always has contact depending on the wedge angle.  This proved to be very useful for this odd board and likely will be useful in the future for a bloodwood board with serious attitude on my rack.

Here is a piece of sapele with a bit of twist.  The only wedge used is the one in the foreground.  Notice again how the wedge is on the fence-side of the leveler so the action of the cutters pushing the board towards the fence will only tighten the wedge, not loosen it.

Another important point has to do with the type of planer you have.  I have a floor-standing (floor-crushing?!) Powermatic 20"planer.  Unlike my Ridgid lunchbox planer, it has power rollers, not pressure feeders (after this post, I'll post about those differences).  "Power" in this case really means it, unlike "power" meaning anything in "power chord" of 80's metal.  Note the following picture:

this is the correct way to place the leveler... there MUST be a leveler at the board extremes.  If you do the following:

the power rollers will press down so hard on the first unsupported inch of the board that the other end will pop up in the air.  Likely your leveler settings will be in disarray or, worse, everything might go amuck while being fed into the planer.  While I'm sure you can see how this would happen on this tiny sapele board, the board from which it came from was 7' long, 11" wide 4/4 sapele.  I had about an inch before the first leveler like in this picture.  The back of the board popped up 3-4 inches as the roller pressed down then when the roller was over the leveler, it slammed it down.  I nearly had very embarrassing laundry.


  • LyttleBryan said...

    First, this looks great.

    Second, this may sound like a very beginner question, but how is everyone cutting these 15 degree notches in their levers? My brain doesn't seem to want to process what tool to use to cut this.


  • HalfInchShy said...

    Hi, Bryan,

    The 15º notches don't have to be dead on 15º; just get something close.

    Let's assume you have some 3/4" thick stock that you'll rip into 3/4" square sticks (so the end profile is a 3/4"x3/4" square). If you want to cut "really close to 15º" notches:

    Grab a piece of scrap MDF at least as long as the sticks. Lower your tablesaw blade height to about 1/8" and run a groove 1/8" from the edge of that MDF scrap. This will become your crosscut backer.

    To make the notches, place that MDF scrap against your miter gauge fence with the groove near the bottom; so, that groove is now 1/8" above the table.

    Keep your tablesaw blade at the 1/8" height (you may need to raise it; it'll become more obvious later and after a test cut).

    To crosscut a notch into a stick, place the stick on the table saw deck with one corner in the groove you cut in the MDF scrap. If you looked at the stick from the side, the face of the stick facing down to the tablesaw deck will be at about 15º. When You squeeze the stick against the MDF, the corner should go into the kerf you made in the MDF: this will hold it at the correct angle and prevent it from rotating when you make the cut (BUT YOU STILL NEED TO SQUEEZE TIGHT... yes I meant to shout that or the stick will rotate and kickback).

    When you push the stick through for the crosscut, squeeze it tight and go reasonably slow until the cut is through then back it out slowly.

    After your first cut, verify that the notch is visible on both sides of the stick. If not, raise the blade a bit. Be aware that a typical ATB saw blade has 'bat ears' on the side for clean cuts, but in this case it will make it look like it has cut higher than it has due to the material left between the ears.

    Now you just need to get some scrap 1/8" thick (your saw blade kerf width) and cut them into triangles.