tag:blogger.com,1999:blog-7523923067078512976.post8243915468258440831..comments2022-07-08T04:55:14.863+02:00Comments on Blue Spruce Woodshop: How I Understand Sight LinesAnonymoushttp://www.blogger.com/profile/17569365598390231433noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-7523923067078512976.post-71994426338780956132016-06-03T09:35:15.414+02:002016-06-03T09:35:15.414+02:00Hello Peter,
to be very honest, that is the most u...Hello Peter,<br />to be very honest, that is the most unexpected comment. :-)<br />But I'm very glad to read your remarks.<br />It was the combination of all parameters which drove me nuts for a while. So your video and blog post was pretty helpful. But there was this last bit missing.<br />Looking forward to find some time this weekend to make some progress, revise my layout and shape the Anonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-12223718121473788942016-06-03T09:02:06.571+02:002016-06-03T09:02:06.571+02:00I already understood from the video that there is ...I already understood from the video that there is an error with increasing leg angles.<br />Your explanation helped to make sure that I'm on the right path of understanding.<br />Can I live with that error? I think yes. Keep in mind I'm hand tool only. I doubt that I'm able to drill with a brace so precisely. Anonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-37121156759081597422016-06-03T08:56:30.679+02:002016-06-03T08:56:30.679+02:00Hi Sylvain,
thanks for pointing out the error.
I ...Hi Sylvain,<br />thanks for pointing out the error. <br />I think it is acceptable for this stool, even if it will be a prototype to figure out all this stuff.<br />But I will keep it in mind for future projects.<br />And meanwhile I could print out the "magic" ruler. <br />Cheers,<br />StefanAnonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-40637342700284071672016-06-03T00:34:36.618+02:002016-06-03T00:34:36.618+02:00Stephan,
it looks to me like you have it rather we...Stephan,<br />it looks to me like you have it rather well in hand. It is a simple calculation of triangles, but rather than turning to heavy math, as you noted, using the sightline ruler, you can simply lay out the rake and splay and derive the sightline and then measure the resultant. The sightline ruler is helpful, because unlike using a ruler and pythagoras, the sightline rule accounts for thePeter Galberthttps://www.blogger.com/profile/02206420121702258974noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-49236119946915803292016-06-02T19:21:51.680+02:002016-06-02T19:21:51.680+02:00Glad to hear that it can be of some help. As Sylv...Glad to hear that it can be of some help. As Sylvain has pointed out, there is an increasing mathematical error as the angles become larger. For example: <br />@20deg resultant the error is ~.75deg..at dining table height this translates to about 1/2" where the leg meets the floor.<br />@30deg resultant the error is ~2.5deg..at dining table height this translates to about 1-1/2" whereGregory Merritthttps://www.blogger.com/profile/08626596539743806187noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-5558706527861945632016-06-02T11:11:07.491+02:002016-06-02T11:11:07.491+02:00The TAN function is nearly linear for small angles...The TAN function is nearly linear for small angles, that is why Gregg's method gives "good enough" results.<br />Although, if 0.5° is the acceptable error, it should not be used for splay and rake angles greater than about 15°.<br />SylvainAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-49780252458890198542016-06-02T07:59:11.487+02:002016-06-02T07:59:11.487+02:00As the discussion shows I hadn't understand it...As the discussion shows I hadn't understand it completely.<br />But now the details are complete.<br />Anyway, it took a while and it was helpful for me to invest some scrap to make some haptic experiences. <br />And Greg's explanations and hints have been very helpful.Anonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-10687322667941001092016-06-02T07:52:20.444+02:002016-06-02T07:52:20.444+02:00Hi Greg,
you made my day (and it is early in the m...Hi Greg,<br />you made my day (and it is early in the morning). The Pythagorean theorem was one of my first thoughts. But I was unsure if I could reflect that to the resultant angle. If I would have double checked the calculation result with the ruler results then I would have been sure earlier.<br />Man, it can be so easy.<br />I'm convinced that there have been some rules of thumb in the Anonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-8216136081550335652016-06-02T04:19:10.434+02:002016-06-02T04:19:10.434+02:00I've been studying this problem for a few week...I've been studying this problem for a few weeks now trying to come up with a short hand that works. It seems the old-timers surly had some rule of thumb to quickly lay this out. I laid out several examples in CAD using three views to find the exact resultant angles. Then I looked for commonalities. I found that if I treated the rake and splay values as units, the resulting hypotenuse was Gregory Merritthttps://www.blogger.com/profile/08626596539743806187noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-23979935139685934942016-06-02T03:45:18.631+02:002016-06-02T03:45:18.631+02:00Greg - there must be some magic here. I think of ...Greg - there must be some magic here. I think of the A^2 + B^2 = C^2 as applying only to the lengths of the two legs (A and B) and the length of the hypotenuse (C). Does that somehow apply to angles as well?Matt McGranehttp://tinyshopww.blogspot.comnoreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-10125325478742320702016-06-01T23:43:38.779+02:002016-06-01T23:43:38.779+02:00Stefan...your making this way harder than it needs...Stefan...your making this way harder than it needs to be. Basic geometry will get you very, very close. I'm not sure why Galbert is using that Bevel Boss thing.<br />These are just triangles. In you above you have two legs and your looking for the hypotenuse.<br />7(squared)+7(squared)=c(squared) thus<br />49+49=98(square root)<br />so first resultant angle is 9.899degs<br /><br />7(Gregory Merritthttps://www.blogger.com/profile/08626596539743806187noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-77779793633032557742016-06-01T21:18:17.349+02:002016-06-01T21:18:17.349+02:00I'm glad you understand it Stefan. I'm sti...I'm glad you understand it Stefan. I'm still trying to visualize the flat drawing in pic one to something in 3D. I'm losing so far.Ralph Boumenothttps://www.blogger.com/profile/10606484453109932074noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-58196982817908616332016-06-01T18:22:56.372+02:002016-06-01T18:22:56.372+02:00Hi Sylvain,
thanks for the hint. Now I think I got...Hi Sylvain,<br />thanks for the hint. Now I think I got it.<br />What was my error? I didn't recognize that on Peter's ruler are half units.<br />So I held my protector to that ruler and thought "fine, that fits".<br />But your are right, that is wrong. Just double checked it.<br />How embarrassing :-(<br />Anyway, I think the rest of my description is just right. But I have to Anonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-7523923067078512976.post-29611589481639828602016-06-01T14:34:56.887+02:002016-06-01T14:34:56.887+02:00If you look at the post (3rd picture)http://chairn...If you look at the post (3rd picture)http://chairnotes.blogspot.be/2012/02/sightlines-revisited.html<br /> you will see that the measurements are proportional to the tangent of the angles.<br />The way you use your protactor gives measurements proportional to [Tan a / (1+ Tan a)]. <br /><br />The greater the angle, the greater the error.<br />For 7° and 7°, calculus gives 9.85°; so 10° is a goodAnonymousnoreply@blogger.com