Woodturner Pro

rtaylor

PRO Member
Has anyone had issues with the calculations being inaccurate for segment rings using Woodturner Pro? I am having real issues. I am using 1/16 accuracy. My ring is 16 segments. Board width 7/8", segment edge length 1", Inside edge 5/8". all dimensions are spot on. Using a wedgie sled so the ring is perfect. The calculations shown are Outside D=4 3/4" Inside D=3". the actual is 5 3/16" OD and 3 1/2" ID. This is happening on various rings, some are OK others are not. Does anyone have any answers to this. Very annoying and hard to design accurately.
 

mfisher

Super Moderator
Staff member
Not sure what is going on with WTP on the 1/16th inch option. I tend to use the imperial decimal inch. Have not had an issue. When my rings don't come out right it is generally my error in cutting SEL. :)

A SEL = 1 for 16 segments would give a circ of 16
16/3.1415 = 5.093 diameter.

You may want to send Lloyd an email.
 
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rtaylor

PRO Member
As long as Woodturner Pro has been out.....this seems really strange. Some of the rings are OK then some are off by a lot. Could windows 10 have something to do with it?
 

mfisher

Super Moderator
Staff member
Your windows10 question would be one for Lloyd. I don't know.

When I have rings that come out either larger or smaller than I expected the majority of times my SEL is off just a tad.
I switched to using imperial decimal inch a few years ago. I also tend to overbuild in width of the board. As long as the ring is not too small I just turn down to the diameter I really want.

I was playing with WTP and the Option settings going from imperial inch, down to nearest 1/16th. The SEL, board width, etc values changed.
imo, since WTP is rounding the measurement (your example of SEL 1") will produce a ring larger than the 4 3/4 OD when set at nearest 1/16th.
Hopefully the board width changes enough to where you can turn down to the 4 3/4 OD.
 

mostlycold

PRO Member
May not be helpful, but I had a couple issues with this myself and two things cleared it up. First, if using the wedgie system, make sure you are cutting from the same side of the stock on each cut (I think Jerry refers to this as parallelism), second, make sure you are “not” using a thin kerf blade on very hard woods, the flex will throw your angles out. You need a full 1/8” thick blade (box stores usually don’t carry these). Specialty stores around here call them commercial blades.

Couple extra thoughts for your problem solving toolkit,
Dan
 

Lloyd Johnson

Administrator
Staff member
The formulas for calculating the various measurements are well known and have been in use by Woodturner PRO for the past 21 years. I guarantee that all of the calculations are correct. One of the reasons I make this guarantee is that whenever I make a change that affects any calculation, I use multiple online calculators to verify that my calculations match theirs.

In Woodturner PRO, all calculations are made in imperial decimal inches in floating point accuracy and then converted to 1/16”, 1/32”, 1/64” or metrics at display time.

If your finished ring diameter doesn’t match the calculation from Woodturner PRO, it means that your SEL is not exactly the same as specified by the software. Remember that if your making a 16-segment ring, an error in the SEL is multiplied by 16 so a little error can make a sizable error in the diameters.

Lloyd
 
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