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Segments and accuracy

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Forum topic by Jack Lewis posted 03-29-2018 09:20 PM 838 views 0 times favorited 12 replies Add to Favorites Watch
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Jack Lewis

346 posts in 1281 days


03-29-2018 09:20 PM

As a general practice among those of you who do segmenting turning, what accuracy do you feel is necessary for the length of a segment, within .01, 1/32, etc? The segments of any given ring would be identical with a stpo block! My experiences seem to indicate that +/- 1/32 is more than adequate with enough padding on ID and OD. Smaller radiused rings do require more padding than larger ones.

How do you all set miter gauges with enough accuracy?I have tried the wedgiie sled and Miter Set and have failures with both. Are the aftermarket miter gauges with higher resolution on angles any better. Do any have readable vernier scales of any accuracy?

I glue up half rings and true the surface before completion but would like to have a repeatable method. I feel .01 degree angle variation for the most part should suffice. I know that 40 and up segments per ring that would still be intolerable, hence my post here today

-- "PLUMBER'S BUTT! Get over it, everybody has one"


12 replies so far

View Lee's profile

Lee

128 posts in 1081 days


#1 posted 03-29-2018 11:34 PM

Jack, Ive had very good results using my wedgi sled and templates to set the angle. seg-easy has the templates all the way up to 48 segments. I also have the incra 1000hd miter gauge and its very accurate but the wegi sled is so much easier to use as long as you use the templates to set the angle. hope this helps, and good luck

-- Colombia Custom Woodworking

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poospleasures

776 posts in 2687 days


#2 posted 03-29-2018 11:38 PM

I do a lot of segmenting and have found any measurable degree of inaccuracy is not acceptable. I used to do half rings, grind the joints to fit then finish gluing. It has taken a long time of trial and error to get several miter gauges set to different degrees. When I have one working like I want it is left that way forever. My 15 degree has been set for several years and the 10 degree a few less years. It is nice to just place one on the saw and know the rings will fit together perfectly. The miter gauge which came with my Shop Fox saw is a very accurate and easy to set to different other degrees needed which I sometimes do. I have made probably every wedgie and sled I have seen and nothing works like the good quality miter gauges.

-- I,ve had amnesia for as long as I can remember. Vernon

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Woodmaster1

1073 posts in 2790 days


#3 posted 03-30-2018 12:45 AM

I use a wedgie sled at 15 degree angle and I don’t touch because it cuts perfect wedges. I made a wedgie sled you can set for multiple angles but I use the 15 degree sled 90 percent of the time.

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TheDane

5552 posts in 3866 days


#4 posted 03-30-2018 01:55 AM

I use a wedgie sled … it has been dead-on accurate.

A friend made a wedgie sled and couldn’t get anything to work. Turned out the two fences on the sled he made were not true (one had a slight taper in it), and he was using a 30/60/90 triangle he found at a dollar store. We re-made his fences out of hard maple, and bought decent triangle at an office supply … now he gets the same results I do.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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splintergroup

2429 posts in 1426 days


#5 posted 03-31-2018 02:55 PM

When dealing with sub-degree accuracy needs, the last bit of accuracy comes from consistent part placement on the miter device (use a clamp) and keeping the same side pressure while cutting so the miter bar rides along the same edge of the miter slot. If the part has an angle already cut on the end use a stop block that references near the center of the part versus the point.

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Jack Lewis

346 posts in 1281 days


#6 posted 03-31-2018 03:47 PM


If the part has an angle already cut on the end use a stop block that references near the center of the part versus the point.

- splintergroup


I see less accuracy when using the center which can vary to the point which should be absolute. Isn’t the length accuracy +/- a few thousandths mute as long as the angle is consistent? I am not asking about complex feature rings. That would be a different story.

-- "PLUMBER'S BUTT! Get over it, everybody has one"

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TheDane

5552 posts in 3866 days


#7 posted 03-31-2018 09:48 PM

Isn’t the length accuracy +/- a few thousandths mute as long as the angle is consistent?

Correct. Within reasonable limits, the segment edge length can vary a bit and it won’t make much, if any, difference so long as the miter angles are correct. The segment edge length determines the outside diameter of the ring … I build in a little wiggle room on both the SEL and board width.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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OSU55

1975 posts in 2193 days


#8 posted 04-01-2018 04:10 AM

For length I use a stop block, anchored in the opposit miter slot. It locates off the corner of the long edge. For angle, as the others said, its best to leave a given angle set up. I used miters and wedjie sled, about the same, but the sled can be shop built and left set. I detail my miter process here. The most segments per ring Ive done is 16. That was enough per ring for me, no desire to deal with what you are dealing with ie need for greaterangle accuracy.

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splintergroup

2429 posts in 1426 days


#9 posted 04-01-2018 02:35 PM


If the part has an angle already cut on the end use a stop block that references near the center of the part versus the point.

- splintergroup

I see less accuracy when using the center which can vary to the point which should be absolute. Isn t the length accuracy +/- a few thousandths mute as long as the angle is consistent? I am not asking about complex feature rings. That would be a different story.

- Jack Lewis

The idea is to avoid using the point which will deflect/crush easily and usually has some tear out. A simple “L” shaped stop block works well.

The length affects the required angle. Consistent lengths mean the angles are all the same. One longer segment requires the end angles be proportionally steeper (think about a simple 4-sided frame with one side being longer).

It’s all relative however 8^) at this point unless the segments are wide, you should never see any gaps if the errors are “reasonably” small.

Typically for segmented circles I make with 6 or more sides I’ll just fit tightly two half circles then trim the facing straight edges for a perfect fit.

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adot45

139 posts in 827 days


#10 posted 04-01-2018 02:48 PM

This is such an interesting thread to me. I use a segment cutting sled that I made and is set at 15* where I make a cut and then flop the board over, slide it down to my stop and then make the next cut. Usually I use board widths of 5 ~ 6 inches to get up to 12” glueups. I’ve heard of the wedgie sled but assumed it was more for the smaller segments for turning rather than the full pie shapes i use. Or, is the wedgie sled capable of cutting boards of that width? My sled is great when it’s cutting “on” but next session it will be off. I’d throw it under the bus in a minute for one with consistant accuracy.

-- David -- sent from my linux box

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gwilki

227 posts in 1677 days


#11 posted 04-01-2018 03:01 PM

Adot: You can make a wedgie sled to take any size boards you like. You would simply space out the two sliding fences so that your boards will fit between them.

-- Grant Wilkinson, Ottawa ON

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adot45

139 posts in 827 days


#12 posted 04-01-2018 03:49 PM



Adot: You can make a wedgie sled to take any size boards you like. You would simply space out the two sliding fences so that your boards will fit between them.

- gwilki

OK Grant thank you. I am going to take a look at the wedgie sled.

-- David -- sent from my linux box

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