Beveling with a Bench Top Planer

I wrote an article about beveling with a bench top planer for Power Fibers last year. Here's the article with a few updates:

There’s a bench top planer in my shop that’s used to mill hardwood for rod tubes. The thought of using it to rough in tapered strips percolated for a while after seeing Tony Spezio’s setup for PMQ strips. I figured hex strips could be beveled the same way. Other makers have used a planer. Harry Boyd has experimented with a bench top planer in recent years. I’m sure there are others that I’m not aware of.

Following is a two part review of beveling with a bench top planer. Part I covers cutting a 60 degree bevel in an un-tapered strip. That can be done with a less expensive router beveller, but the planer will work if you don’t have a beveller. Part II explains cutting a taper into a beveled strip. Using the planer significantly reduces the amount of final hand planning.


Part I – Planing the Bevel

The first step is to straighten the nodes, sand or smash them and remove the enamel. The beveling process described here must start with straight nodes and a reasonably flat enamel side. I touch up the sides of the split strips on a power sander and run them through a router beveller to square them up. You don’t need a beveller to do this. They could be squared up with a hand plane, or saw the strips with a band saw instead of splitting them.

The squared up strips must have a 90* angle at one of the enamel edges to begin the beveling process. If you don't start with a reasonably accurate 90* angle (give or take a few degrees), the process described in this article will not produce 60* angles in the finished strip. I realize I’m beating this point into the ground, but if you don’t start with the correct angle, you’re just milling kindling for next winter.

Square up the strips to about the same dimensions so the planer height doesn’t have to be adjusted for every strip. The butt strips will be a little bigger than the tip strips depending on your target dimensions. Plan the rough cut dimensions ahead as usual.

Three different wooden forms are used in the beveling process. The first and second forms are not tapered and they have significantly different bevels. Both forms can be made with a table saw. Look up “forms” in the tips section at www.bamboorodmaking.com for more details on making wooden forms. The first form is functionally the same as a hand planers “first form”.

It’s critical that the enamel side of the strip is facing the short side of the first form with a 90* edge nestled into the form as illustrated in the drawing above. One pass through the planer will cut the first 60* angle. If the enamel side is not properly positioned, the strip will go in the scrap pile after one pass.

With the strip properly positioned in the form, set the height of the planer so that the rollers just touch the bamboo strip enough to pull the strip and form all through the planer at the same time. Don’t try to hog it off, the form may hang up in the planer and the sharp edges of the bamboo strip will cut grooves the drive rollers.

The height may need to be adjusted a couple times for the first strip until the cut is at the right depth. The goal of the first pass is to cut down to the enamel edge without reducing the width of the enamel side. That will take one or two passes through the planer depending on the size of the squared up strips. As the form and strip are pulled through the planer, carefully hold the strip down in the form as it enters the planer. It the strip pops out of the form as it enters the planer, the planer will ruin the strip. Here’s a photo of a strip after the first pass.

Note that the planer knives did not touch the surface of the form. There’s no reason for the planer to cut the strip that close to the form like you would with your final forms and a hand plane. I split most of my strips to .25 inches wide. So the bevel in my first and second forms is about .125 inches deep or one half the width of a split strip.

The opposite side of the first form is the second form. The second form has an un-tapered 60* equiangular bevel. The 60* angle of the strip should fit snugly in the bevel of the second form as illustrated below. One pass through the planer will produce an equiangular 60* triangle.

Place the strip in the form as illustrated above with the enamel on either side of the bevel. Adjust the height of the planer and feed the form and strip through the planer as described for the first form. Again, the goal is to cut flush with the enamel edge of the strip without reducing the width of the enamel side of the strip. Here’s a photo of a strip after one pass thorough the planer with the second form. Flip the strip and make a couple more passes through the planer if the angles aren't quite right.

The strips are now ready to be tapered. There’s no practical difference between using a planer or router beveller up to this point; but from now on, the amount of hand planning required to finish the strips is reduced significantly. I’ve been binding the strips at this point and heat treating before cutting the taper.



Part II – Planing the Taper

The strips have been heat treated; six packs have been selected, staggered, and cut to length. A couple extra inches have been added to the end of the staggered strips to allow for snipe. Most bench top planers will cut a divot in the last couple inches of the strip (i.e. snipe). It’s usually not enough to matter, but adding a couple extra inches eliminates the problem.

The third form is adjustable and tapered. A standard wooden planning form may or may not work. The form needs to be light enough for the drive rollers to pull it through the planer when they’re only touching the bamboo strip.

I made an adjustable form of white pine to keep it light and easy to make. My form isn’t as accurate as I would like but its close enough. Its 6ft long with a 60* tapered bevel cut on one side. This form can be made with a table saw. A router table with a 30* chamfering bit is perfect for cutting the bevel, but that could also be done with a table saw. As mentioned earlier, search the tips section at www.bamboorodmaking.com for instructions on how to make an adjustable wooden form.

The form depth is set to the final dimensions. It takes two or three passes through the planer to reach the roughed in target diameter. For the first pass, the height of the planer is set so that the drive rollers just barely touch the bamboo at the butt end - just enough to pull the form through the planer. That planer setting is noted as the start point for the rest of the strips. The form is fed into the planer butt end first. It won’t start cutting until the fourth or fifth station depending on the slope of the taper. It will cut progressively deeper from butt to tip. After the first pass, the planer will cut the same amount of bamboo from end to end.

Multiple passes are made with the first strip while stopping between each pass and checking the diameter until it’s at target. I’ve been stopping about 80 thousandths over the final dimensions of the taper. The planer height is noted at the target setting for the remaining strips. The rest of the strips are fed through the planer with two or three passes from the start to target planer heights.


The strips in this picture are ready for final planing. I was having trouble with splinters as you can see in this photo. But that problem was solved by soaking the strips in water a couple hours before planing them. Yes...I'm soaking the strips after heat treating. That doesn't appear to affect the quality of the finished rod. I just dry them in the oven before gluing up.



I don’t worry too much about keeping the knives razor sharp. Here’s a photo of a knife that’s planed the strips for eight rods. This knife could not be used for normal planer work. It would leave micro grooves and ridges in a piece of hardwood. This set of knives will only be used for roughing strips from now on with occasional sharpening.




Here’s a roughed in set of strips for several two piece one tip rods. Tapering the strips with the planer saved a lot of hand planning.


Here's a few final thoughts:

Pros:
1. Just about any inexpensive bench top planer will work so long as the knives are easy to change and relatively inexpensive to replace or sharpen.
2. The wood forms are cheap if you make your own.
3. The automatic feed feature of a planer is very cool.
4. A bench top planer is safer to use than most home made milling machines.
5. It only takes four or five passes through the planer to be within 80 thousandths of final dimensions starting with a squared up strip.

Cons:
1. An expensive planer may not work. If the planer has a high volume chip removal system, it will suck the strip up off the form and shred it. For example, the DeWalt 735 tends to shred bamboo strips.
2. Milling bamboo will ruin a set of knives. A different set of knives will be needed for other planning projects.
3. Hogging off too much may cause the form to hang up in the planer and the sharp edges of the bamboo will cut grooves in the drive rollers.
4. Most bench top planers are really loud. Hearing protection is advised in most cases.