Showing posts with label Constraint. Show all posts
Showing posts with label Constraint. Show all posts

Saturday, July 4, 2020

Additional Horsepower

When starting out in woodworking, most think they will never be able to afford all the tools they need/want/desire. But with patience, and the accumulation of years, the gaps fill to a point where, at least I don't feel limited by the tool set I have. In some cases, that means that while I might have multiples of some things (shiny planes & shaves) I might be missing some basic functionality that many others assume as first rung tool ladder purchases (power miter saw, plunge base router). I often find it surprising to compare tools with other woodworkers, and find we often have odd gaps where our tool paths diverged either from specialty, ethics (power/hand), space, or finances.

This is a long way to say I don't have sawhorses. I've never owned them. Whenever I needed them I had always somehow made do with some other temporary support and thought "I should get some saw horses" and then do nothing until the next time they would be handy... Of course there are numerous great designs (intrigued with the knock down burro design,) and they can even be purchased, but that all seemed like something I'd get to someday, but never did.

What I did have was a crazy PVC pipe monstrosity. This bulky, ugly cage was something I knocked together a couple of years ago when I was enamored by the material and I was getting into Gymnastic Strength Training. I made this contraption to do parallel bar dips. I never really liked it, but figured, "no problem, I'll be up to using rings for everything in no time!" Narrator: He did not quickly progress to rings. (Rings are hard). While I do hope to get fully on to those ring progressions, I finally decided the cage had to go and I needed something better. I landed on Krenovian parallel bars.

To be honest, I had not really liked the design before. They always seemed a bit too precious and complicated and light duty for the somewhat rough, disposable nature of sawhorses (though certainly not the most complicated I've seen) Still, I landed on them because of the lack of protuberances in the undercarriage interfering with their (or rather my) action.  I also admit they look nicely stored away, and would certainly match my emerging shop vibe once burned "finished".

While I'm pretty sure I could have come made them from memory, or customizing based on an image search, I recalled an old Fine Woodworking article on the topic. I found the one I was after (with of course some time rummaging through adjacent articles as one does when going through FWW) and found the one I remembered.

It was by Anissa Kapsales I didn't recall this fact, in fact at the time I read this originally, I didn't "know" her at all. If you don't, she is a delight and adds a lot of fun to Shop Talk Live podcast which is a must listen if you are this far into this post and not bored to tears. I got no little kick out of this,  it was like finding out the interesting person you met as an adult, actually was in your high school and you just hadn't known them then.

I did make a few alterations to the design; it seems the designer had prioritized their function as sawhorses over gymnastic parallel bars, weird. This would not do for me, but I did compromise and make them a little shorter than initially planned so they can (with a simple plywood top panel) also stand in as out feed support for my table saw. (Yeah, the irony of another simple thing that I've somehow avoided) I also raised the lower stretcher a bit to better balance the split and to align with my saw bench height. I used some different thicknesses based on scraps I already had on hand, and I rounded the top edges and added an angle cut to tweak the feel/look to taste.

draw bore pegsNow that I've completed the pair, I have a newfound appreciation for their design. They are pretty smart, a functional tutorial along the lines of a traditional bench sawhook that is slightly more complicated than it needs to be, but has benefits beyond its intended function. Heres why; in building a pair, a new woodworker would make 4 blind mortise and tenon joints (I draw bored mine), 4 through wedged M&T joints and 4 (pinned) lap type joints. This is all in the context of very economical material usage that really can be made from short odd scraps in a variety of thicknesses that I almost guarantee you already have on hand. This is an ideal project for someone new to joinery looking for practice in a project with some leeway on the end result.

Beyond the simple project that packs a lot of learning in, Krenov's design reminded me about one of the goals I'd hoped to achieve with this blog.

It's hard to believe that in the seven-ish years I've been occasionally blogging, I've never really discussed what I may be most qualified to talk on. In my secular job, my expertise, such as it is, is in the field of engineering, applying and analyzing geometric dimensioning & tolerancing (GD&T). In this realm, there are numerous problems that engineers often try to solve by over constraining a design (think, wobbly 4 legged table vs stable tripod) sometimes it's obvious, but unavoidable, sometimes it's less obvious but by taking a constraint theory approach to looking at the system, the root cause of the problem (and often then the solution) emerges.

I've often thought that woodworkers have had to deal with and apply constraint theory problems over the ages (with the corollary that due to the constant wood movement changing the dimensions of parts, it is a lesson that must be learned) Many vernacular designs I have observed have (un)knowingly have addressed these constraint problems. For instance, a four legged table with a normal apron structure, the top normally has enough flex and will "hinge" across the high corners resting easily on all four legs, but an excessively stiff undercarriage will not give in this manner, introducing the dreaded wobble.

These sawhorses similarly are a light frame that is easily warped/twisted which could seem flimsy in that direction but actually will allow the four legs to rest on an irregular surface. With a load applied these easily accommodated one leg on a ¾" horse stall mat. The wedged/pinned joints will hold tight through any induced flexing of the structure, which the hardwood (oak in my case) can likewise absorb. The cutouts in the sled feet make this flexing all the more possible allowing solid ground contact, with any downward force applied. And the direction that force is applied it is incredibly strong for its weight, since the upright is directly inline with the applied force. The narrow body and unobtrusive feet are other definite advantages to the design.

Overall these Sawhorses parallel bars will be a nice addition to my space. and I wish I hadn't waited so long to make some, it was a good fun quick project that uses very little material and doesn't take up much space when completed. I hope this inspires you to make a pair, as I think they would be at home in a shop/gym, (unless you are already progressed to using just rings, in which case I hate you and hope you rot :)

Saturday, June 15, 2013

A Place to Tie Your Shoes

Like most five year-old boys on the wrong side of the Velcro dawn, I ambled frequently with untied (Incredible Hulk) sneakers while I struggled to gain the fine motor skills and muscle memory that would eventually come to be second nature and repeated thousands of times in restraining my footwear. In time, I mastered that skill and by the aid of my parents learned somewhat useful things like cooking, cleaning (don't tell my wife), lawn care and car repair. Among the learned skills I value now are: how to look closely at a thing, and how to create a thing you can be content with despite limitations of money, time, or ability (you'll always have them).

So when my parents got to living in their recently built (it'll never be "finished") home and they needed a place to store shoes and a seat to sit and tie them that fit tidily into a space by the exit, I knew this would be a chance to apply what I've learned. Of course, don't look too closely for fear you'll notice the mistakes (as I simultaneously point them out)
.

This project had several design constraints:
  • Of reclaimed lumber from a barn dad took down
  • Store shoes on a shelf
  • Sturdily support my parents
  • Fit between 2 doorways, but not interfere with pedestrians


These constraints probably could have been satisfied with a barn joist cut-off on cinder blocks, so additional design goals were considered:
  • Some sort of "delighter" to separate it from its utilitarian usage
  • Provide some feminine balance to the masculine utility (symbolizing a bit, Mom & Dad)
  • Provide as wide a stance as possible without interfering with the future trim or pedestrians
A few of the things I learned on this project:
  • Angled, chair-like joinery is best cut prior to shaping cuts if possible, to prevent your mind from melting.
  • Avoiding nail holes completely in barn wood is impossible
  • Sketching many wild and crazy shapes will eventually yield an idea for connecting A to B
  • Mr. Maloof style joints, provide a sturdy connection with only one degree of freedom unconstrained, but you really need a fastener for that last DOF (which he knew). 
  • Small personal details attract far more attention than angled housed lap joints or wedged through tenons even if they are by far the easiest bits to make.

My parents have given me inumerable life lessons, from tying shoes, to following passions. Their quirks have often turned out to be the very "delighters" that I treasure most in my own personality. Thanks Mom & Dad for adding fun details, but not skimping on the structure.




Friday, June 7, 2013

Three Birds With One Stone!

Reading woodworking magazines and blogs doesn't ever make your I'd-like-to-build-it-someday list get shorter. For several years Schwarz guilted me with each variation of his saw bench (never-mind I don't use my xcut/rip saws much). After reading The Anarchist's Tool Chest It pained me to see my tools stored in the open, so...naked and exposed. But given the time commitments I had at the time, I knew there was no way I could build a full-size chest fast enough to prevent my saws and long planes from oxidizing....again. About this time, CS started talking about get'er'done vernacular furniture of necessity and 6 board chests in particular. If I squinted a bit, I saw a way to check off 3 projects in the proverbial "weekend." (~15hr shop time)

So I set about a quickly built design to meet my design requirements and efficiently use standard cheap materials* without panel glue-ups.

  • Dust Tight
  • Use home center 1X material (1x12 width means can't fit saws and planes on one level) 
  • Bench planes (heavy) on lower shelf ( LV BU jointer longest plane)
  • Saws on sliding till for accessing lower planes without removing (saws dictate final length and height.)
Originally, the sides were to be 2 ship-lapped boards to get the height required and allow for seasonal expansion (fixing the theoretical cross grain over-constraint problem with 6 boards) but when I headed to Menard's I discovered that the pre-milled "car-siding" was of better quality and would be a cheaper, faster, better way to get my box built.

Then I built it pretty much as described by CS and finished the outside with a few coats of leftover paint (black over red)

The useful items that separate this from a standard boarded chest:
  • Dust sealing
    • The batons that keep the top flat fit tight against the ends.
    • A thin "tongue" was lapped into the batons (sturdy joint) and fits into a the topmost groove of the car siding.
  • Sides
    • I rabbeted the ends to provide racking support to the structure then glued and nailed the top and bottom boards.
    • The center board works like a floating panel door with no glue or nails. It floats in the T&G joints and the rabbets on the ends prevent it from sliding or letting dust in.
  • Design
    • I've been anti-straight line for a while and so sketched some curves & chamfers where I could. In the end I think it's OK, but with the T&G car siding lines drawing the eye, I would embrace rectilinear if I were to do it again.
    • The sliding till was the hardest thing to lay-out to fit the saws I needed to fit in there, yet be narrow enough to access the planes. I like the till a lot and if I ever build the ATC, I'll incorporate it on the middle runners in CS's chest.
This simple chest allows storing my long tools with less fear of oxidation and allows me to get on to making other furniture & tools. Someday, I'll make a full size "legacy" (not fancy) chest, but then, this one will house my apprentice's tools upon becoming a journey(wo)man. In fact, as I was putting on the 2nd coat of black my 9yr old said, "when you're gone, I think I'm gonna paint it purple..."

*Materials:
1-1X12X10'
2-1X6X10' car siding (speeds up T&G construction and was less expensive than similar quality 1x material)
hardwood scraps
hinges/chain