Help with tapered posts

[Jeremy2200]

Alright guys i need some help. Yesterday I cut about 800bdft of pecan for a guy and he has some big cedars he wants cut into tapered posts. Proably 12 inches on the bottom up to maybe 8-10 inches at the top. We had a junk log we tried it on and couldn't get anything consistent. I told him i would find out how to do it and come back after i get through with these 2 big jobs I am starting tomorrow. Thanks
Jeremy

[Brian_Rhoad]

You need to know 3 things before you start cutting the log. The size of the large end of the post. The size of the small end of the post. And the exact length of the finished post.

If the large end is to be 12" square the log to 12".

Next mark the post for the finished length where you would cut it off.

Using a carpenter's square, mark around the log on each side and each end where it will be cut for the finished length.

Line up the square line on the 12" end with the edge of the mill bunk closest to the saw head when the saw head is back where you start to cut.

Now you need to raise the other end of the post 1/2 of the difference of the post size on the small end.
If the small end is to be 8" that would be 4" difference and 1/2 of that is 2" (12" - 8" = 4"    1/2 of 4" = 2")

Raise and clamp the post so that the small end is 2" above the mill bunk or bed at the square line where the post will be cut off on the small end.

Set the saw at 12" and make your cut.

Turn the log 90* or 1/4 turn and do the same as the first cut. Set the saw at 12" again and make your cut.

Turn the log 90* or 1/4 turn.

Make sure you keep the square line on the big end at the same place on the bunk as you turn the log to keep that end the correct size. The saw should enter the log close to that line each time you start a cut.

Now you need to raise the small end the correct amount to make the last 2 cuts.

If you measure to the bottom side of the post you need to raise it 1/2 the difference of the large and small end + what you have already cut off. Using 12" and 8" that would be 1/2 of 4" + the 2" you already cut off or 4" total.

The post should be 4" above the mill bunk or bed at the square line on the small end.

Set the saw at 12" and make your cut.

Turn log 90* or 1/4 turn and repeat last step for final cut.

Your post should be cut with a taper from 12" to 8". The taper should be equal on all four sides.

You could cut the post to the exact length but I've found it to be easier to leave it a little long.

If you cut it to length you make your measurements at the very ends of the post.

[ladylake]

 I think saw one face wide enough for one side turn 90* and make another face wide enough, turn 90* then put about a 2" shim under one end and saw to your size, then turn another 90* and put the shim in the same place and saw to your size. You should have a tapered post but will need to square the ends

[ladylake]

I think saw one face wide enough for one side turn 90* and make another face wide enough, turn 90* then put about a 2" to 4" shim (4" if the one end of the post was right on a bunk and the shim was right on the other end) under one end and saw to your size, then turn another 90* and put the shim in the same place and saw to your size. You should have a tapered post but will need to square the ends

[garyfg]

Why would you want to taper the post anyway?

[ladylake]

 
Just for looks on a front porch or something like that.   I cut some for poles on horse drawn machines that turned out good about 2 years ago, a long time for a fuzzy memory.    Steve

[laffs]

 i  made some tounges also for horse drawn equipment. you need to shim 2" on one side and shim 4" on the opposite side to get it to come to 8". best to square up the ends before you start the taper. the tounges i made were 4"tapered to 2 1/2" and flat on bottom, the tapper started up about 2' from the butt

[Jeremy2200]

Thanks everyone for the help. That sounds great. We tried for about an hour just trying to figure it out with no luck. The guy wants the post for columns on a front porch of a house.

[Brucer]

I've cut quite a few tapered posts for people. There's a couple of tricks that make life easier. First of all, though, saw the post square to the larger dimension. Then near the big end use a carpenter's square to make a line all the way around the post -- this is where you want your saw blade to enter as you cut the taper on each face.

Trick #1:

1) Figure out how much taper you want on one side -- you calculate it as ...
   (Large end dimension - Small end dimension)/2 divided by the length.
2) Measure the distance -- center to center -- between the two bed rails closest to the ends.
3) Multiply the taper from step (1) by the distance in step (2). Cut a shim this thick, about 2-3 feet long and as wide as your be rail.
4) Cut a second shim twice as thick as in step (3).

Having these two shims will save a lot of measuring and adjusting -- especially if you'll be sawing more than one post.

5) After you've squared up the post to the larger dimension, lift the small end, insert the smaller shim on the appropriate bed rail, and lower the post so it rests on the shim. Set the height of the blade so it will just enter the wood at the reference line you drew around the post. Then saw off the first taper -- and keep the piece you sawed off!

6) Flip the piece 180 degrees -- not 90 degrees -- lift the small end and insert the larger shim on the appropriate bed rail and lower the post onto it. Set the height of the blade as before and saw off the second taper. Keep this piece as well.

Trick #2:

Turn the timber 90 degrees and place the two tapers on either side of the cut faces. In other words, put them back where they came from. This is the secret of getting an accurate tapered post.

Now repeat step (5) for your third taper (but you don't need to keep the piece you saw off this time around.

Flip 180 degrees, keeping the first two tapers with the post, and repeat step (6).

---------

Here's why trick #2 is so important. When you put a taper on two adjacent faces, the angle between them ends up to be slightly more than 90 degrees as measured at right angles to the faces. The steeper the taper, the greater the error. This error accumulates as you turn the to each new face.

To avoid the error you need to keep the centerline of your post parallel to the side stops, which is what the two tapers do for you.

[Brad_S.]

I built a jig. I wanted an 8" base so I started with a 9" cant and split the difference on each side so the blade had something to bite into right from the start. The base is always pushed to a stop on the end and shims like Laff described are always placed in the same spot on the other end of the jig. After the first pass with the 2 inch shim, the cant was rotated 180 degrees and the 4 inch was used. Then I turned it 90 degrees, again inserted the 2 inch shim and also shimmed the side away from the post as well (or else the cut would have an angle) and repeated the process.







Same client wanted two with a taper to start then a standard square the rest of the way up.




[img]

[Brucer]

That last post looks like it would be fun to saw .

[nas]

Had to cut a couple of tapered posts last week, and I was reminded of this post.  They had to be 18"x18" at the bottom and 10"x10" at the top and 11' long.  Started with a log big enough to get 18x18 on the bottom.



Then I cut it to an 18x18 and blocked it up 4" on the top.  Notice the bottom is sitting on a bunk, so I can keep the saw height at 18".



After cutting 2 sides at 4" I turned it and raised it 8" for the other 2 sides



and here is the finished product.



Nick