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tirapop

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Posts posted by tirapop

  1. linkfest

    DIY carbon bikes

    http://www.sheldonbrown.com/rinard/howibuil.htm

    http://www.bmeres.com/carbonframe1.htm

    motorcycle bits with molds and lost foam

    http://www.mci.i12.com/carbon/index.htm

    "tube socks"

    http://www.oneoceankayaks.com/Wshophtm/carb_tubing.htm

    At big aerospace companies, we mostly use pre-preg (resin pre-impregnated woven fabric and tape). Dry fibers and liquid resins are used mainly for repairs. Pre-pregs don't require all the squeegeeing to wet out the fibers and then work out bubbles and remove excess resin. Pre-pregs require compaction with vacuum bags to squeeze out trapped air. Pre-pregs are more expensive and require refrigeration.

    One of the tricks the repair guys use is to "make pre-preg" for repairs. They take a sheet of plastic film and stack the cut layers of fabric on it. They measure the correct amount of resin and pour it in the center of the stack. They take another sheet of plastic, put it on top, and then use a scraper like spatula to distribute the resin from the center, out to the edges. Once they've got it evenly distributed, they peel off one sheet of plastic film and stick the exposed surface to the part they're repairing or in a mold or on a mandrel. They peel off the out sheet of plastic film and then stick on a breather ply (that allows excess resin to squeeze out and to allow volatile products of the cure to escape. The whole thing gets vacuum bagged and then either cured in an autoclave/oven (if it's small enough) or under a thermal blanket. Resins will cure at room temperature, but, for structural composites the strength improves with elevated temperature (250°F or 350°F) cures.

  2. Anyone here have a Ryobi BT3100 table saw?

    I've had mine for about a year now, and I'm increasingly annoyed by the unusual "SMT" (sliding miter table) and lack of standard miter slots, and its habit of going out of adjustment every few cuts.

    Most of the reviews and opinions I've read about it are quite the opposite, so I'm just wondering if I have a dud, or maybe it's just my weird personal preferences.

    Along the same lines, does anyone have any budget-priced ($300 or less) table saw recommendations?

    Consult the experts.

  3. I agree with Mick, changing just the horn, but retaining the rest of the Tele profile, looks odd. It's like the Tele's on acid, but, it's only just kicked in.

    Maybe add some corners on the upper shoulder to show that the psychedelics are taking control. The control plate looks a little too Tele and abandoned by the shrinking pickguard. Consider rear routing the controls, having the knobs right on the wood and using a smaller metal plate just for the toggle. Both the pickguard and control plate would look like they were shrinking... I can't remember if that's "eat me" or "drink me" in the Alice in Wonderland story.

    I'd go for unstriped.

  4. A friend expressed interest in CAD programs. I have ProDesktop, from back when it was free. I'd seen SketchUp stuff on Make magazine blog, so I pointed him that way. We're old school CADAM, CATIA and he was having problems driving SketchUp. To help him out, I downloaded SketchUp to get a feel for it and help him out. It has a sharing feature where you can upload your models into a google database for people to check out/download. I started looking around there and found a very nice model of a Stratocaster.

  5. You should probably skip the neck, given the time you have to complete this project. The idea sounds interesting, but, how did you plan to put frets into sheetmetal fingerboard? Welding, soldering, brazing, or pressing frets into metal would be pretty time consuming and tedious. You could try something like Gittler. (video) Looks like a lot of work, too.

    Focus on the body. 1/2" flatstock sounds way too thick, too heavy. I can't remember the name, but, there's a production metal bodied guitar that has sheet metal sides, nicely rolled edges and perforated metal fronts and backs. Specimen makes aluminum guitars fabricated from sheet metal.

  6. so is it a stronger construction, the horizontal laminate? or weaker... hmm I am a bit confused.. But I am sure going to try to build one that way :D sometime in the future ..

    The answer is... it depends.

    It depends on where you put the bondline in the thickness of the neck compared to where you put the bondline for the vertical laminate.

    A horizontal laminate can work. People keep mentioning an example that does work: the fretboard. It bends with the neck, picks up load, and gets that load through a horizontal bondline. For a beam in bending, which is what the neck is, the peak horizontal shear is near the center of the thickness. It stays pretty close to that as you move out from the center and then tapers off rapidly near the edges.

    You asked whether one construction was stronger or weaker. A better question is, "is it strong enough?" Probably. Think about glue-lam beams used in construction. They're subject to bending loads in the same direction as a guitar neck... horizontal laminations. If you want cheap insurance, you can dowel through the laminate stack (part thru, so it doesn't show through the back and gets covered by the fingerboard) to take some of the shear out of the bondline and into the dowel.

  7. What are folks talking about when they say horizontal laminates? Like, laminates in the same plane as the fingerboard? Glue's not strongest in that direction, and the joint is taking on a lot of shear stress that's entirely absent (pretty much) in a 'traditional' laminated neck.

    Actually, glues are strongest in shear (where the parts want to slide against each other on the glued surface). They're weaker in tension (pulling perpendicular to the glued surface) and peeling. Well designed bonded joints and weldments transfer load in shear.

    But, yeah, a vertical laminate can have much less or no shear across the bondline. There's probably is going to be some, depending on where the bondline is relative to the tuners. The neck is getting pulled into a bowed shape, by the strings acting through tuners and where the string contacts the nut. If one of the vertical laminations is doesn't have a tuner in it pulling it toward the the bridge, the adjacent lamination that does have a tuner in it is going to pull it into the bowed shape... through the bondline in shear.

    The loading on a horizontal laminate bondline is probably less severe than the load on the bondline of scarf joint for a tilt back head. That bondline has more shear, over a smaller area, and a peeling component to the load.

  8. Another senseless tragedy.

    I've long thought they ought to develop a drug for people with personalities/psychoses prone to murder-suicide. It would cause them to confuse the order and kill themselves before they manage to hurt anyone else.

    There's a tendency to look at crimes like this or Columbine and think that this is something uniquely modern, driven by violent media, etc. I heard the girl, now woman, responsible for the "I don't like Mondays" shooting was up for parole. I looked up the incedent on Wiki and then followed some related links. I stumble on the entry for the Bath School Disaster. I'd never heard of it before. 1927, Bath township sets up a property tax to pay for a modern school. It's enough to set off the school board treasurer, a failing farmer facing foreclosure. He bombs the school killing 45 people, mostly children.

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