edi malinaric

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About edi malinaric

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  • Birthday 07/24/1939

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    Cape Town

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  1. edi malinaric

    William Fry Internal Scraping Method

    Hi Don - this leaves me a little puzzled. The modulus of elasticity of a string remains unaltered but any change in the internal stresses certainly affect the frequency. Comment? cheers edi
  2. edi malinaric

    William Fry Internal Scraping Method

    Hi Don - I'm always happy to learn - what way does it work? Hi David - unfortunately I don't know. It was just a curiosity that I noted at the time. After recovering the wings with fabric and returning the glider into service one loses touch with it and returns to enjoying flying your own machine. In carrying out AIrworthiness Inspections on wooden gliders one spent a lot of time tapping glued joints to locate glue failures. On a pair of ASK7 wings I spent one whole evening tapping every joint in every built-up rib (think model aeroplanes) - and marking every "hollow" sounding joint with a piece of 20mm x 20mm red insulation tape. When the Committee, who'd being hassling me to "just get the job done", saw the number of suspect joints, they backed off and allowed me to complete the repairs in peace. Last I heard it is still flying - 30 years later. cheers edi
  3. edi malinaric

    William Fry Internal Scraping Method

    Hi Lars - my thoughts about the use of varnish in fine-tuning were kick-started when someone wrote that some varnish "wear patterns"in old Italian violins just didn't make sense. They postulated that maybe the final tuning efforts involved modifying the outside varnish by adding and removing varnish in selected areas to modify the acoustic response. In the example I mentioned - of aircraft dope altering the pitch of wooden sailplanes. It was the D-box section of the wing - typically formed from 1.5mm plywood. As in instruments, one attempts to keep the coat as thin as possible - so mass change would be negligible. However the dope does shrink as it dries - introducing a tensile stress on the outer surface of the ply - which is the probable cause of the change in pitch. Some years back I purchased a violin "in the white" from a pawn shop - mainly because of the case. The poor violin had been painted over with white PVA paint. I think that I'm going to have some fun recording tap tones on the front and back and them see how they change as I scrape away the paint. cheers edi
  4. edi malinaric

    William Fry Internal Scraping Method

    Hi Lars - thank you for your post. Two points... - for clarity, would it be possible to plot the "difference" graph with the negative values pointing downwards? - if one added a couple of coats of varnish over the "too thin" area how would it affect the frequency? (when painting plywood sailplanes there is a definite increase in tap frequency after respraying) cheers edi
  5. edi malinaric

    Have you ever seen such a tip?

    Hi - interesting. How did it affect the CG? How does it play? cheers edi
  6. edi malinaric

    Stradivari's secret was a concept?

    Hi All - just catching up with this thread again. Channels apart - just looking at the angle of the purfling - have I been out of step while struggling to keep the scalpel square to the floor? - or is there a case to be made for cutting the purfling groove square to the surface of the plate? Similarly the f-holes? That the back has asymmetrical thickness is a surprise - I would have expected it on the front plate. Does this suggest that the back has more of an effect on sound production than I thought. Does the asymmetric thicknessing give credence to post-assembly tap tuning by scraping away on the outside - before varnishing? Shall I throw the verticality of the soundpost into the mix? What a lovely picture - thank you. cheers edi cheers edi
  7. edi malinaric

    Tapering the Ribs

    Hi David - I always considered it to be a "pre-stressing" of the belly analogous to tensioning the bow hairs, the timpanous membrane of a drum, straining the steel "bumps" of a steel drum, pre-stressing of steel reinforced concrete beams... - off-setting belly sag might also be included. That improvement in sound has been mentioned is no bad thing in itself either. cheers edi
  8. edi malinaric

    Bottom of Cello

    Hi HoGo - decorative or covering an error - yes. It's unlikely for support - the saddle "load" ends up in the bottom block - it's unlikely to linger in the ribs. regards edi
  9. edi malinaric

    Your worst buy on Ebay

    Mmmm - guess my Llandudno, Cape Town via Llandudno, Wales can't compete cheers edi
  10. edi malinaric

    Worth Repairing/Restoring?

    Hi Blank face and Jacob - forgive an engineer his love affair with rigid triangulated structures. One accepts that they aren't really necessary, as established by the centuries of surviving BOB violins. My thoughts were actually on making the corner blocks as light as possible - such as drilling a hole down the centre - just a mind exercise. Good workmanship is always a given. I built my first sailing dinghy in ~1959 - a cold moulded hull built of two layers of spruce over a mould. Other builders complained that it was impossible to build a hull down to minimum weight (100 lbs). The designer told me to just build it as shown on his plans and resist adding extra bits and pieces for extra strength and I would end up with a minimum weight hull. The engineering student in me then set about examining every bit of wood that went into the hull - could I lighten it? - if I halved the thickness of the side deck ribs and reduced their spacing could I gain stiffness and reduce weight? - drilling 3 lightening holes through the ribs also helped - the gluing stringers that located the fore and aft bulkheads were shown as 1/2" square spruce, I used Obeche (fractionally lighter than spruce) and reduced them to 1/4" x 1/2" triangular sections placed on either side of the bulkhead and halved the weight and doubled the glue area... and so on and so on. When it came to being measured, the hull was 14 lbs under the limit. I then started building in extra stiffening all over the place to bring the weight up to the class limits. Twenty six coats (at which number we lost count) of primer, paint and polyurethane varnish did their bit and gave us an absolutely fair hull. Andy #26 remained unbeaten for 4 years and was chosen as the "mother hull" from which a mould for fibreglas hulls was taken. I later built another hull - but this time with three layers of tola veneer. Each strip was about 100mm wide and each one had to fitted exactly to the preceeding plank in order to ensure that there were no built in stresses in the shell. When doing violin plate joints under Brian's supervision he was complimentary about my workmanship - how could I tell him that doing a violin plate was kinder-garden stuff compared to matching a 3mm thin, 100mm wide and 1.5m long floppy piece of spruce and having to get the joint perfect while wrapping it around the curve of the hull. That would amount to, let's see, 5 layers, about 40m of joint/layer - that's 200m of fitted joint - let's just say about 600 violins worth. I still use that little Stanley 102 - fits nicely into the palm of my hand - an old friend. cheers edi
  11. edi malinaric

    Worth Repairing/Restoring?

    Hi Blankface - ah good - normal service has been returned.... - Let me disagree with you. Those "logs" triangulate the corner nicely - giving a much better and stiffer arrangement than any linen stripes. One could even make a case that they are the natural progression towards lightening the instrument. cheers edi
  12. edi malinaric

    Worth Repairing/Restoring?

    Hi All - run for cover - the end of the world must be coming closer... - more in agreement than not! :-) Maybe that label is genuine??? cheers edi
  13. edi malinaric

    Worth Repairing/Restoring?

    Hi Guido - to quote the reply given to the street violinist who asked a world famous violinist what was the best way get to perform in the Carnegie Hall... "Practice, man, practice" More soberly - since he top is off... cheers edi
  14. edi malinaric

    Worth Repairing/Restoring?

    Hi Mapfluke - ignore the nay-sayers - go for it! By the end you will have learnt... - how to make and fit post facto upper corner blocks - make and replace a bottom block - align and re-glue a bottom rib joint - remove glue runs - make and refit an ebony nut - make and refit an ebony saddle - glue on a top - make and fit a soundpost - make and fit a bridge All these skills you would have to learn while building your first violin - so what's not to like? cheers edi
  15. edi malinaric

    Scroll eye question

    Hi Jacob - nice nice work - congrats. cheers edi