How to make Tapers and Parallels

[rmorris]

Alright I ran out of what I call “blanks” on my last bow build and before I build my next one I wanted to stock back up on blanks once again. What I call blanks are rough cut bamboo parallels that I use for making parallels and tapers. To start off I took 10 bamboo flooring boards and ran the first one bottom side through the planer till the small groves were gone. Once I get a smooth pass I then ran the other 9 boards through.

 

 

 

I then drop the planer down about .015” and run a pass on the side with the factory finish to remove it and I am then ready to start doing work with the table saw.

 

[rmorris]

In order to get the most blanks out of a single floor board I prefer to set up my table saw a little bit differently. First thing I do is take out the 10” blade and replace it with a 7-1/4” circular saw blade (you can do this because they each have a 5/8” arbor and you will not exceed the max RPM on the table saw) and zero clearance insert I made out of Corrian.

 

The 10” blade has a width of about .104” while the 7-1/4” blade has a width of .070” this narrower blade comes in handy later and for about $14 makes a great blade.

 

 

After the new blade is installed I check to make sure the blade is square with the table and then I am ready to start cutting.

 

[rmorris]

Just a FYI a 7-1/4 " blade will restrict you max cutting thickness to just under 2".

 

[rmorris]

Before I show the correct way to cut the tong and groves off the boards I do want to show the wrong way to do it just incase someone does not know better or thinks they can save time by not re adjusting the rip fence… so do not do it this way!!! You will get hit by bamboo projectile and will not get straight cuts.

 

You need to set up 2 different cuts in order to properly remove the tong and groves the first cut will remove either the tong or grove and then after re adjusting the fence cut the remaining part off.

 

 

You should now have bamboo boards with clean edges on all sides.

 

[rmorris]

By now you will have noticed that there is some defects in the bamboo and you will want to try to make each cut from here on out so that the defects are on a cut line or the small scrap piece you are left with if possible.

 

I now set of my rip fence for a 1-1/2” cut.

 

At this point I start using a push block because of the narrow cuts.

 

Each original board will now give you two 1-1/2” boards and a smaller scrap piece. I think the scrap is large enough that you can get two 1-3/4” boards if you are making recurves.

 

After all 10 boards are cut I am left with 20 , 1-1/2” boards.

 

[rmorris]

This next part I have gotten mixed reviews on but I do feel it is safe as long as everything is set up properly, so I will go into a little more detail here. The jig I made here is an adjustable fence for cutting thin parallel strips.

 

The jig remains locked down so it does not move if there were to be any kickback. The two small pieces of wood on top serve several purposes; first off they act as a stop and visual reference so I do not put my hand in the blade, second they keep the narrow pieces of bamboo from vibrating and jumping around and third they stop any kickback because they actually apply a little bit of friction and pressure to the thin bamboo strips not allowing them to move too easily.

 

The two small pieces of wood have the be adjusted for every thickness that is why I prefer to cut so many at a time and not have to go do all the adjustment every time I need a few blanks. On this current setup each 1-1/2” board produced two parallels that were .120” thick and one that was on average .130” thick.

 

About one and a half hours later I had myself 40 parallels that were .120” thick and 20 that averaged  .130”.

 

Now this may just by my personal crazy way of thinking but I am a little OCD about keeping the two .120” parallels together because I feel they “should” have the same properties. To be more specific I like to take the two that are the same from each board and use one piece in the upper limb and the other in the lower limb also making sure that the same part that is the tip in one limb is also the tip in the other limb.  I can’t prove this makes a difference in the consistency of a bow but I like to think it does.

[rmorris]

Here is a link I have posted before showing the cuts in action

 

[rmorris]

Here is also some pictures of some other things I have cut besides bamboo with this jig. I have not found the perfect bow to use them in but who knows I may do the bow swap this year and use these aromatic cedar ones...

 

[JamesV]

I use an almost identical set-up, even the same blade and it works great. Only one thing I do differently, to remove the factory finish I run my blanks thru the tablesaw, removing as little material as possible. The finish destroyed my (new) planer blades.

[rmorris]

Alright now that I have all the blanks made it is time to make tapers and parallels for laminations. I start off by making a taper sled out of a dry hard wood, in my choice I chose Purple Heart. The next thing you will need is a taper and thankfully you can buy perfect ones in .001/” and .002/”. You will need to make sure you square up your piece of limber for your taper sled. I do the rough cuts on a table saw and then I do a quick thin pass on the plainer to ensure the board is parallel.

 

At this point you can now attach your taper to your soon the be taper sled. I prefer to use double stick tape (use the permanent not the removable kind).  I use about 9 pieces of tape to attach the taper to the board.

 

Start off slow and keep running you taper sled through the planer until you get one continuous cut. Once you get a continuous cut all you have to do is remove you taper and you have taper sled.

 

Remember the thick end of the taper sled makes the thin end of the taper and vice versa. I run the taper through the planer from thin part of the taper sled to thick. I also put an arrow on my taper sled with a marker do I don’t forget. Now all you have to do is tape your bamboo blanks to the taper sled with double stick tape and run them through the planer. The resulting product will now be a perfect parallel and to get different thicknesses all you have to do is adjust the height of the plainer.

 

[rmorris]

Now parallels are much easier to make to make. Parallels thicker than .075 I am able to just place on a nice smooth maple board and they cut just fine.

 

 

If I need parallels thinner than .075” I then use the double stick tape method and flip my taper sled 90° and I can cut parallels as thin as .040” without the plainer shattering the bamboo.

[rmorris]

Here is a quick picture on how to quickly tell the difference between a parallel and a taper without measuring because sometimes it can be very hard to tell if you have a taper just by looking at it. The parallel bends symmetrically and the taper does not.

 

 

Hope this little demo helps out with making your own tapers and parallels. If you do not feel comfortable working with wood this thin and power tools I recommend you buy your tapers and parallels.  
If you are not comfortable cutting the blanks with a table saw you can also do this with a band saw it just quicker for to use a table saw and I get cleaner cuts.
Also if you have a drum sander you can use it in place of the plainer.
 Bamboo is the only material I have been able to cut thinner than .075” with a planer and not shatter the material. I hear you can use a drum sander to create veneers as thin as .025” with the double stick tape method but I do not have a drum sander so I have not tried it.

[eflanders]

Nice job Roger.

[StoneAK]

Very cool I also cut my laminates on a table saw but I bought the Grizzly 10" drum sander for about 500.00 it works like a charm for those tapers. Awesome trick with the tablesaw blade swap for the circular saw blade I guess I am heading to the hardware store in the morning. God BLess

[Buemaker]

Excellent and most interesting. You say to use the permanent type of double stick tape and not the removeable kind. I am a bit confused here, does it mean that you do not remove the tape?
I have a pack of 72" long bamboo boards and wonder if I glued two factorymade tapers on a parallel board with the thin ends butting in the middle and placed a parallel bamboo strip on top af that, then ran it through the planer. I wonder how it would come out,if it would be a smooth transaction in the middle, must be tried out.  Bue--.

[rmorris]

Bue, the removable tape does not have the holding power you need, but the perminate tape comes off bamboo just fine.

[JJB]

Very informative, great detail.  Thanks for sharing.

[ridgerunner1523]

that was awesome. i do have one question on the tapers. i didnt quite get how you made the taper board. could you happen to show in a video on youtube how you do that? thanks

[strungstick]

Ralph - Any particular place you get your vertical bamboo?  It looks to be pretty good stuff.

[strungstick]

Ridgerunner, I don't know if this will help you but the easiest way is to just double side tape a pre-made taper to your sled an run it thru your sander. The other way I've done it is to just take your desired taper (.002) and multiple it by the length of your taper sled and make a spacer that dimension to elevate one end of your sled and run it thru.  You need to make sure your sled is thick enough it does not flex as it is run thru your sander. (I use 6/4 solid oak) Example - to make a 40" sled at a .002 taper you make a spacer .080 and elevate one end so when it is run thru you obtain your desired taper on your sled.  Check your finished product and adjust accordingly moving your spacer in or out as needed until you're happy with your sled.