Tell us about yourself!

Complete Your Profile
  • DavidH677 commented on gravitino's instructable The First Color Photograph15 days ago
    The First Color Photograph

    I have seen the Maxwell Ribbon with my own eyes, and marvelled.But I've no idea how he did it without access to colour-sensitive emulsions.But even if it's a Fascinating Fake, Maxwell's great insight - that three colour separations can almost wholly satisfy our three-colour eyes - is still a massive achievement.David (ex Kodak)

    View Instructable »
  • DavidH677 commented on sbkirby's instructable Drill Press Laser Guide3 months ago
    Drill Press Laser Guide

    That would be true with a Dot laser that only generates a Line of light. But these are Line units that each generate a Plane of light. (Naturally the planes need setting up to intersect at the exact quill axis). So the only workpiece height constraint is to be lower than the lasers.

    View Instructable »
  • Building a Giant Baseball Chair (from 2x4s)

    Nice one, JackmanWorks :-)

    View Instructable »
  • Building a Giant Baseball Chair (from 2x4s)

    HEY! The surface of half that ball has been tampered with, using sandpaper!Seriously though - great project :-)

    View Instructable »
  • How to Build the Self Feeding Fire - All Night Fire

    Thanks, Bob :-)

    I love the whole concept of a chore-saving device that needs special equipment and constant supervision. Reminds me SO much of Computers! David

    View Instructable »
  • DavidH677 commented on beul's instructable PICKPOX1 year ago
    PICKPOX

    Think hard first - don't let the divot spacing limit your capacity. There's a lot to be said for variable spacing - unless all one's packages are the same thickness :-) Though just because the divots are there doesn't force one to use them. Great idea, thanks!

    View Instructable »
  • DavidH677 commented on diymontreal's instructable Edison Lamp1 year ago
    Edison Lamp

    That shows y'all live on the left side of the Pond :-) On the right hand side, it was Sir Joseph Swan who claimed priority, won the patent battle with Edison and was made a Chevalier de la Legion d'Honneur. Eventually the rivals merged their UK businesses, and Ediswan screw-fittings for bulbs are coded ES even to this day.Great design, thanks! David (England)

    View Instructable »
  • DavidH677 commented on kniegmann's instructable Hand+Ink Letterpress in Aluminum2 years ago
    Hand+Ink Letterpress in Aluminum

    There are several layers to the answer :-)I've put some detailed points below, but the simplest answer is to look at the image (shrunk by the website). The centrelines of the grid are 3.5mm apart, and the straight edges are not entirely straight. Meanwhile the centrelines of the rings have a radius of 0.4mm. The outer diameter of each ring is roughly a millimetre, and you can see that it's not actually ever so round. The inner circle is a bit over half a millimetre in diameter, and looks even rougher. BUT to keep perspective, remember that it's actually finer that 300dpi halftone letterpress dots.1) The POSITION of the etch lines is as good as the resolution of the laser cutter.2) The WIDTH of bare metal line in the paint is never less than the width of the laser beam, and is more if...

    see more »

    There are several layers to the answer :-)I've put some detailed points below, but the simplest answer is to look at the image (shrunk by the website). The centrelines of the grid are 3.5mm apart, and the straight edges are not entirely straight. Meanwhile the centrelines of the rings have a radius of 0.4mm. The outer diameter of each ring is roughly a millimetre, and you can see that it's not actually ever so round. The inner circle is a bit over half a millimetre in diameter, and looks even rougher. BUT to keep perspective, remember that it's actually finer that 300dpi halftone letterpress dots.1) The POSITION of the etch lines is as good as the resolution of the laser cutter.2) The WIDTH of bare metal line in the paint is never less than the width of the laser beam, and is more if it's not focused accurately or if the mirrors are dusty. Variations in the thickness of the paint will make small differences in the width of the lines. I'm using a shared cutter that gets hammered 40 hours a week and isn't maintained properly - you could probably do better.3) The SMOOTHNESS of each etch line is a mixture. Like all Laser cuts, there's always a slight ripple caused by the stepping motion. That is amplified by the way the heat burns the paint - the slightest hesitation and the line becomes a fraction wider. Then there's the bubbling of hydrogen - every tiny bubble slows down etching briefly in one spot until it rises to the surface.Finally, paint is thin and fragile - look hard at my picture and you can see places where the paint has flaked and the line wobbles - especially at corners. Be careful how you wipe bubbles in case you wipe paint.4) UNDERCUTTING depends on the thickness of the metal - but that's the same for all chemical etching. To give you an idea, this etch is roughly 0.3mm wide by 0.2mm deep.5) The quality of HALF-ETCHED surfaces depends on the crystalline structure of the metal. You can see that the bottoms of the grooves are pretty uniform and flat, but nothing like as smooth as the un-etched top surface. But this material is work-hardened aluminium, not annealed printing plate. (Some of this isn't relevant to Letterpress printing, but some folk want to etch for other reasons.)

    View Instructable »
  • DavidH677 commented on kniegmann's instructable Hand+Ink Letterpress in Aluminum2 years ago
    Hand+Ink Letterpress in Aluminum

    I have etched metal shapes using a low-power laser-cutter designed for wood and card. I spray-painted the metal sheet, etched through the paint with the laser, then etched through the metal chemically, finally cleaning off the paint. This process would make good metal printing plates.The aluminium squares in this close-up photo are 3.5mm centre-to-centre (but Vector-cut, rather than Raster as you would need for a Plate).

    Yes, my factory ruler was a folding one :-)Time was when every major European trading city defined it's own inch, ranging from about 20mm to 55mm in length. Damn this pesky Globalisation :-)

    There's a special soft rubber sheet to make printing plates (or block stamps) on a laser cutter. The laser cutter at my night-school comes with software to taper the sides of the raised parts, the better to resist compression in the press.

    View Instructable »
  • Makeshift letterpress with a cuttlebug - Part One

    I can see why you trimmed round the image to avoid an impression of the surround - letterpress images in books don't have impression marks around them. But individual block Prints on art paper do have such impressions and it adds to the Printy feel of the medium. Clearly the folder still needs trimming aesthetically, but four straight lines does the trick :-)Good luck with the photosensitive plates - my local print workshops both sell them and make excellent use of them in their work.

    View Instructable »
  • DavidH677 commented on kniegmann's instructable Hand+Ink Letterpress in Aluminum2 years ago
    Hand+Ink Letterpress in Aluminum

    Great project - there's nothing like letterpress.I chuckled at the millimetres because I once worked in Denmark. The factory issued me with a wooden ruler marked in English Inches, Norwegian Inches, Swedish Inches and Metric Inches. Swedish inches were strikingly different, and measurements in Swedish feet have confused many an industrial historian.

    View Instructable »
  • DavidH677 commented on Adam Gabbert's instructable Live Edge Tea Light Holder2 years ago
    Live Edge Tea Light Holder

    I've seen these catch fire - wind blows the flame, a little wax gets on the wood, and then . . . Or maybe one doesn't notice that a candle has burned low, the wood starts to smoulder . . . So now I ALWAYS include an IKEA glass tea-light holder. It's a shame in a way, because yours (and mine) are so beautiful without, but there's nothing pretty about a burned-out house.

    View Instructable »