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Praetorium Honoris

Friday, June 9, 2023

Never Mind...Figgered it out

 Well, last Monday I was in a bit of a funk.  MBD had asked for some help with her home renovation.  Specifically she wanted me to redo her living room book case and include some arches at the top for style.  To be precise, the dimensions called for an Ellipse.

 

This is an ellipse.  Important points are the focus and the major axis.Source:softschool.com

 I had commented asking our readers for a few pointers to get me going in the right direction.  Thankfully I received a few.  However, STxAR was able to give me a few ideas and more importantly search terms which got me pointed towards this video.




OOPS, Coding error with the video originally. Sorry.

Anyhow, I decided (e.g. made a good decision) to try a practice run on a piece of cardboard.  Good thing.

 

 As can be seen, the intersecting point of the ellipse and the wall are short by about a half inch as is the top point and the ceiling.  However, the far intersection is darn near perfect.  Not sure what I did wrong.  Checked and rechecked all the measurements and they were accurate.  So.  put away all my tools and had a recuperative glass of wine on the front porch with my wife watching the T-storms rolling by.

Yes, Beans, they missed us.  But town was getting a gully washing.

The following day, I decided I was going "All In!" and using a sheet of the lauan plywood leftover I had on hand.  Marked out the rectangle representing the shelf including the 3/8" overlap on either side.  Figured out the two focal points on the major axis.  (You DID watch the educational video above, dincha'?).  Measuring and measuring again all the appropriate points.  Tied some pull cable I had left over to a figure 8 shaped metal pin on both ends and tightened it.  Removed the nails from the ends of the major axis and put them in just inside the focal points and looped the cable over it.  Pencil pull to the top of the minor axis...Went Left, perfect!  Went Right, perfect!


 

I'm defining perfect with a tolerance of 1/8".  Go ahead, Sue Me!

Treated myself to a celebratory trip to  Lowes for new Jig Saw blades, came home and cut along the Ellipse.  Amazing how accurate a new (e.g. sharp) blade will cut.  In any case. Voila! An Arch.

Mrs. J's bookshelf isn't quite the same size, but it's close enough to get MBD excited about the results.

 

The plan is to make my 4th trip to College Station on Monday. (The Rev, MBD and MG will be in Austin with his family over the weekend).  I'll take the Cutouts and check the measurements on the actual bookshelf.  Come back home Tuesday and using the bottom cutout piece as a template, rout out the three arches.  Bring them back to College Station on Thursday (5th Trip), drop them off, spend the night there.  The following morning, Mrs. J, MBD , MG and I will drive to Galveston and board a Royal Caribbean Ship for a little cruise vacay.

During which I plan to do a lot of napping and NO driving.

Again, thanks to all the readers who offered help and advice on how to do this project.  Got me pointed in the right direction, it did.

Thanks

Peace out, y'all!



40 comments:

  1. We've been circled by thunderboomers but nada for a week or more. Grass is getting crispy and the mosquitoes are looking parched. So I feel for you.

    Thanks for doing this post. Had a tooth decide to try to kill me, so am going in to get it gacked out.

    Nice job, by the way, looks good. Can't wait to see the finished product.

    ReplyDelete
    Replies
    1. Beans,
      Hope your Dentist visit is successful with a minimal amount of pain.
      Thanks
      juvat

      Delete
  2. Hmmm....thingamabobs....and whatchacallits....way too technical for this guy. Bookshelf looks good juvat.

    ReplyDelete
    Replies
    1. Nylon,
      Nah. Just took a bit of patience, something I'm not noted for, but am endeavoring to improve.
      Thanks
      juvat

      Delete
  3. Such a smart commenter group. Power of the Social Internet. - TB

    ReplyDelete
    Replies
    1. TB,
      Yeah we do have a pretty wide assortment of skills in our readers don't we? And everybody that responded offered something that I hadn't known but helped with the final product.
      Thanks
      juvat

      Delete
  4. ah, yes. and where would all us jack leg carpenters be with out CAD..... cardboard aided design????

    ReplyDelete
    Replies
    1. Yeah, but I wish I could figure out where I screwed it up. Ah, well at least I can use the plywood version as a template for the router when I do it for realsies.

      Delete
  5. Well, sir. I'm probably gonna celebrate helping my brothers in arms. I might just buy a cheese burger and onion rings today... Glad that helped out. Hey, next ellipse, if one side works and the other is a bust, just cut the card board in half and flip it on the minor axis next time. Mirror image and all that. Well done brother, well done! Another "dad comes through" moment to awe the chillins.

    I've thought about cruises, but if the boat gets a flat, how do you walk home?? That's the question that I have no answer for. Until I do.... I'm a landlubber.

    ReplyDelete
    Replies
    1. STxAR,
      I didn't think about that, but I had three objectives in this part of the project. First was to be able to draw the curve. Check! Second was to build a prototype for design approval and measurement accuracy confirmation. Third was to have the cutoff shape available as a router guide. I think flipping cardboard might not have filled the last very well. But...another trick of the trade for future reference.
      Thanks
      juvat

      Delete
    2. I never thought of using cardboard as a router template. I'd have figured you'd use it to layout the curve on some plywood. That would then become your template for router work after sanding to the line. I may have to try that and see it I can make it work. Saving a step is important as age advances!!!

      Delete
    3. STxAR,
      I probably got in a hurry in describing what I'd intended to do. The original plan was cardboard for layout, then transfer to plywood then cut. But when the cardboard got screwed up, I began to think it was movement on it. So I went straight to the plywood. Don't know if it was more stable, or just that I'd had a practice run. Most likely both. In any case...
      Thanks
      juvat

      Delete
    4. Happy to be of service to you brother. Waiting for the dry run to hear it's a perfect fit. Great job there lead.

      Delete
  6. Well done. Sorry I missed the opening post. Over the years of making those in costume and scenery shops, cardboard and thin Masonite or plywood were the usual base (cardboard more in costuming, where it was rarely not on a cutting table, and not waving about in the air.) Error sources: string stretch (I finally went to 1/16" stainless aircraft cable, now, there are ultra-low stretch plastic cables), knot or clamp slipping, pegs or marker not vertical (drill vertical holes in benchtop to hold nail, make a pencil holder to hold it vertical), being bumped by someone or something.

    ReplyDelete
    Replies
    1. HTom, Thanks. I used Nylon pull string used by the electricians who came and installed our whole house generator. It had virtually no stretch. But I think I screwed it up by looping it around both end posts doubling it's length. It wasn't much difference in length, but I think it was enough. Once I cut it to a single length and used the figure 9 hooks it worked fine. Just out of curiosity, where'd you buy aircraft cable and how did you anchor it in a loop?
      juvat

      Delete
    2. Both times I bought it, the university supply shop had a ten foot length, without a kink, within a day. I don't remember the cost, wasn't much, or what the "real" use was. Shop made NO-LOAD clamp, 2" piece of 1" steel pipe, drilled and tapped for two 1/4" x 20 thumbscrews. Pull the ends through (opposing) finger tighten one screw on one end, aljust length. tighten other screw on both, losen first clamp, tighten on both. When done, move clamp to one end, coil over-under for kinkless storage in 9" x 12" sturdy envelope. They're probably still being used, a half century later, if not lost.

      Delete
    3. HTom,
      I think what you describe as a no-load clamp was what I was searching for. I got it done, but...It would have been a bit easier if I'd have had that.
      juvat

      Delete
    4. The braided wire used to hang pictures might be an acceptable substitute.

      Delete
    5. Don,
      Yeah, I thought about that, but at the time, I couldn't find the wire nut to connect the loop. Neither Lowe's nor Home Depot employees knew what I was talking about. As mentioned above, I didn't know the specific name, so note of the employees recognized what I was describing.
      juvat

      Delete
    6. If that design has a name, I don't know it. It was described to me by a teacher (thanks, Jim!) "NO LOAD" is a warning, it can and will slip without warning.

      Delete
    7. AHhh. Thanks
      juvat

      Delete
  7. Nice! Who said math wouldn't be useful once one was done with school?

    ReplyDelete
    Replies
    1. Sarge,
      Not I. But it's not the math, it's the APPLICATION of the math that stumped me this time. But second time's the charm.
      juvat

      Delete
    2. A friend asked me to calculate the area of a pentagon for a Veteran's Memorial they were planning (for fill and concrete estimates). Not trivial, taking me a few hours to remember how, using geometry (horrors) and trigonometry(worse). Typed up a full page of the calculations mainly so I wouldn't have to remember how to do it all over again (with my Handbook of Standard Mathematical Tables softy crooning "It has been so many years Fernando, since you have held me in your hands". Then drawing the pentagon using the results with compass and ruler to make sure of the calculations (success) [which is how it would be laid out on the ground with string (wire so as not to stretch) and tape measure]. Turns out the construction company didn't know how to calculate it either. Their estimate was woefully short.

      Delete
    3. Don,
      As I learned from that video, the secret to an ellipse is pick any point on the perimeter and draw a line to any two points on the major axis. The sum of those two lengths is the length of the major axis. Had courses in Geometry at both HS and College. Didn't know that until this post. Doubt that would work for a pentagon though...after all, nothing works at a pentagon.


      Just sayin'
      juvat

      Delete
    4. I...The planned memorial pentagon plan was to represent the five services. The friend after struggling with it, suggested that we just add the new sixth Space Force and make it a hexagon...

      Delete
    5. That would work.

      Delete
  8. Argh I wish I could watch the videos. I'm at anchor in New York Harbor, but since it's a third world country, there's not enough cell signal during daylight hours to load video. Saved for later, though, and the final curve looks fair as can be, too. I can't cut a fair curve with a jigsaw to save my life.

    ReplyDelete
    Replies
    1. PD,
      I feel your pain. Our internet service out here is a bit iffy if the weather is bad and since you're stuck inside and both the web and TV service depend on that service...Well I get a bit more shop time.
      Thanks.
      juvat

      Delete
  9. "more importantly search terms"

    Right there is 3/4 of solving anything, especially involving building or repairing things, knowing what to call it. Harry Turtledove wrote a post-apocalyps (aka The Big Oops) titled "Secret Names" about the shamanistic necessity of knowing the true name of things in order to conjurer with them.

    When I worked for a handyman I would take a part or fitting into the hardware store as go right to the customer service desk, "I need one of these, please!" "Whatchewgot? Oh! A thermjiggler for a jim-jam! Aisle 6, left side, about 3/4 of the way down. Can't miss 'em."(Yeah, right... just watch me). But from that day I had the Secret Name, the True Name, and so able to join the ranks of the jim-jam illuminati.

    ReplyDelete
    Replies
    1. Joe,
      Yeah I'm a big friend of the customer service desk. Saves a lot of time and teaches you a thing or two. I think I've mentioned this before, but our local Lowes has a couple of retired plumbers/carpenters etc. I also try to seek those folks out the better to insure that what I have in mind doing and what I should be doing orbit around the same planet. Then I make it a point to come back with pictures and thank them.
      Seems to work wonders.
      juvat

      Delete
    2. In a neighboring town, we had a family-owned hardware store (sadly closed last year of 90 years in business) so packed with stuff you could barely move down the aisles. You never tried to find anything. You would describe as best you could what you needed, and they often would lead you to the basement (equally packed) down an aisle to an obscure shelf. Exactly what I was looking for.

      Delete
    3. Don,
      I would LOVE to have visited that store. Another chip of Americana down the drain. Rats!
      juvat

      Delete
    4. I haven't been in a store like that in a coon's age. They always seemed to be run by two brothers who had opened the store when Christ was a corporal. Never an empty wooden parts bin or drawer, including parts for machines and systems that hadn't been made since before the Great Depression.

      Delete
    5. Joe,
      Yeah, I'm a bit jealous!
      juvat

      Delete
  10. YAY!!!!! Great job!!!!!

    I think I even understood the video...he was going along, and I'm thinking "this is hurting my brain! I would use a pencil and a line of string" and then that was what he did! Only thing I could think of why it didn't work the first time is could the cardboard have stretched/folded/slipped just a bit? Didja tape it down with duct tape so it wouldn't move--at all?!?!

    Anyhow--it looks very nice. Ya get major Dad points on this one for sure!!
    Enjoy your wine vacay! And be careful with all that driving--buncha nuts on the roads these days--just saying...

    Suz

    ReplyDelete
    Replies
    1. Suz,
      All those things are possible. I thought I got the CAD template secured and didn't see it move at all, but...something went wrong. I'm just glad I've got a pretty good cutout finally. And am gonna be prayin' hard on Sunday that the piece is wide enough. Should be, but...
      Follow up with Cardiologist went great, BP was down 19 points and all the squiggly lines were normal. They asked what I had done differently. I told them about your "NO CAFFEINE" edict. They agreed, asked how the withdrawal went. Well, that was speshul! But...it seemed to have worked. So, thanks again for the advice.

      Delete
    2. Very glad the cardiology check went awesomely!!
      Yup, might not be fun getting off the caffeine, however, having A-fib thumping along, having to pay out the wahzoo for more meds with all sorts of nasty side effects, having to deal with not being able to eat green veggies, or squirting blood for hours when ya knock a knuckle in the woodshop...that can be special also. Switching to decaf is fairly easy all things considered. Plus, if you can slow down the A-fib, ya decrease your stroke risk...and with 2+ grand babies around, you really have MUCH better ways to spend your days then rehabbing from a stroke. Trust me on that one!!!
      Plus, need to keep you healthy so Sarge can continue to have his Mondays off! Priorities, doncha know. :)

      Suz

      Delete
    3. Suz,
      All good points. Thanks
      juvat

      Delete

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