Slide Rule Targeting for SHIII/SHIV

[sluissa]

either I'm doing something wrong or my slide rule is wrong or something, but near the end when you're calculating speed, no matter how I work it, when I put 1 with 3.5,
2.4 =/= 6.85 it's about 8.43 on mine.

everything else seems to work out pretty well with an error or less than 1(usually less than .1), but on that particular problem, I can't seem to get it to work

[Puster Bill]

Originally Posted by sluissa

either I'm doing something wrong or my slide rule is wrong or something, but near the end when you're calculating speed, no matter how I work it, when I put 1 with 3.5,
2.4 =/= 6.85 it's about 8.43 on mine.

everything else seems to work out pretty well with an error or less than 1(usually less than .1), but on that particular problem, I can't seem to get it to work

I think I know what is going on.

If you are working with the C + D scales, you have to move the slide (which has the C scale on it) so that the right-most index mark (the '1' on the right) on the C scale is over 3.5 on the D scale. Then move the cursor to the 2.4 mark on the D scale, and read the speed (6.85 units per second) on the C scale.

If you are using the A + B scales (which I prefer for this), put the 3.5 on the B scale underneath the middle index mark (the '1') on the A scale. slide the cursor to 2.4 on the B scale, and read the speed on the A scale.

I suspect you put the 3.5 on the B scale under the middle index of the A scale, then slid the cursor to 2.4 on the A scale, which will read 8.4 on the B scale.

[Puster Bill]

OK, I re-made my circular slide rule from the sphere site, and put the 'banjo/is-was' on the back of it. I also highlighted the S scale on the circular rule so that it is instantly recognizeable (it's the yellow band below):




And this is the Attack Course Finder side:



I trimmed it to fit on the backside of the slide rule.

By the way, excuse the crappy pictures. Regular camera is broken, so I have to use the webcam to take them.

An interesting experiment would be to mount them both on a board next to each other. Since I have to tote this thing with my laptop, I don't really have that luxury

[jmr]

Wow very nice! Is that card stock you're using there? Your cut circles look damn near perfect to me! Did you use regular old scissors?

As an aside, having never used a slide rule before and not being the most mathematically adept person out there, I was up until 2am scoping out the web for a user friendly guide on slide rule operations. I came across this site at UC San Diego where a professor holds a seminar on slide rule operations. How about that! He has a 13 MB .pdf file of his PowerPoint presentation here Good stuff for beginners.

[Puster Bill]

Originally Posted by jmr

Wow very nice! Is that card stock you're using there? Your cut circles look damn near perfect to me! Did you use regular old scissors?

As an aside, having never used a slide rule before and not being the most mathematically adept person out there, I was up until 2am scoping out the web for a user friendly guide on slide rule operations. I came across this site at UC San Diego where a professor holds a seminar on slide rule operations. How about that! He has a 13 MB .pdf file of his PowerPoint presentation here Good stuff for beginners.

Yep, it's cardstock. I use it for making my own QSL cards. Every layer is laminated, including the transparencies. That makes it more rigid, and it protects the print.

As for the cuts, yes, I use regular old scissors. I just cut right along the lines, and I take my time. For the actual circular slide rule, I got my compass from high school and drew a circle on the back of the cardstock that had the slide rule printed on it, centered on the pivot, that I pre-punched. Then I just cut along the line...

I did it while my 3 year old son was in for a nap. Took about 45 minutes total, being careful, but I already had the cursors from a previous incarnation of the slide rule, so that saved me some time.

I'll have to check those links out, sounds cool.