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Posts posted by KeithHowell

  1. The scale length we used on the original Afri-Can guitars was 25" which worked out perfectly with the 22 fret in line with the edge of the can and the strings anchored at the other edge. The break angle over the bridge was just right.

    A later iteration was extended to 24 frets with the 24th fret level with the edge of the can and the strings still anchored at other edge. This made the break angle on the bridge too shallow and we never pursued it further.

    How are you going the fix the can to the neck? Ours were a neck through with the end bolted against the end of the can below string anchor point. The can in itself, at least the ones we used to get around here,  is not strong enough to resist the string pull without some sort of bracing.

    • Like 2

  2. Cant see that working either! Unless it is attached to a random orbital sander which will keep the block relatively stationary with respect to the fretboard. 

    Scrubbing back and forward is going to always round the board to the lowest radius in contact over the area it is in contact with

  3. If the OPB3 is specifying a 50k pot for volume that's what you should use. Without a circuit diagram of the OPB3 preamp its not possible to say if a 250k will make a difference or not BUT the 50k is probably an integral part of the preamp circuit and will most likely give you all sorts of unknowns if you change it to a 5 times higher impedance.

  4. Quote

    I suppose that glueing the top up to the blank prior to resawing is impractical? I just dove in here and have done zero thought on what is being aimed for....let me re-read.

    I don't think that is a bad idea at all. Sandwich the maple between two pieces of stable mahogany then resaw down the middle of the maple.

  5. The wire is either a centre tap for the secondary of the transformer or a voltage tap for a different voltage output. Very difficult to say without a circuit diagram. If its a centre tap it would be connected to ground.

    However if you don't understand mains wiring take it to someone who does. Messing with mains side of amplifiers can KILL you if you don't know what you are doing!!!!!!!

  6. I had my own blade made up to fit my radial arm saw.

    I went to my tool sharpeners who took a thin blade they had lying around about to be thrown out and ground it to the kerf width of the stewmac blade.

    It cost me about $10! It helps having a long standing relationship with them I suppose (and my father before me).

    • Like 2

  7. It is most likely a mistake in your wiring.

    Without knowing the specifications of the switch you are using it is very difficult to know if the diagram and the switch illustrated correspond.

    Having said that these pictorial diagrams, I find, are almost impossible to trouble shoot with. Far better is a proper schematic of the circuit.

  8. Don't solder on to the back of potentiometers! It is asking for trouble! Chances are you will overheat and damage the pot or get a cold dry joint or both!

    Some pots have a solder tag connected to the case for this purpose. If you cant find these buy some solder tags which fit over the shaft of the pot and bolt up against the body of the pot.

    I don't know where this solder on the back of the pot came from. It is BAD practice. If we had of done this in our electronics training practicals we would have been failed outright! It probably came from some notorious penny pincher trying to save a few cents!

  9. I've never done a whole fret board but I have filled a few slots where in a moment of inattention a slot got cut in the wrong place. 

    I found that using rosewood veneer and cutting slices with the grain vertical NOT across the board (ie cut your strips off the end of the veneer) ,gluing in with CA then sanding while the glue was still liquid and working the dust into the cracks made a close to invisible repair.

    Running the veneer with the grain running across the board shows discontinuity in the grain of the fret board. However in your case I presume you are going to re cut with the identical scale length so most of the veneer will be cut out again and the fret itself will cover the cut so you could use any wood really but matching the wood species would probably be better.

    • Like 1

  10. 44 minutes ago, Prostheta said:

    ...Yes...it's actually SUNNY! .  

    I know....here in the middle of the UK.  Unbelievable!  I thought it was a UFO at first and it scared the cat for sure.  I passed some young parents down the street saying to their toddlers, "...it's called the SUN.  It's like the RAIN, but not so wet...."

    The sun is a mythological character from the Kalevala. Don't try and convince me otherwise! 

    Well here its actually raining. The sun has taken up permanent residence and has been beating down relentlessly for months with no respite. We have only seen a break over the last 10 days! Now of course with everything so dry the rain is causing havoc washing away topsoil causing potholes in roads etc.

    Great guitar and especially your method of gluing the bindings. We used to use a similar method when applying veneer sheets to foam cores for making radio glider wings.

    Have you looked at Trevor Gores neck joint method? It is a double tenon bolted in both planes.

  11. In terms of string tension an acoustic archtop there is no exception. Acoustic archtops perform better when there is an optimum amount of down force on the arched sound board. This is directly proportional to the angle of the strings over the bridge.

    Given the tailpiece height at the same as the bridge the force is all in line with the strings. Lowering the tailpiece (or raising the bridge) will create a vector of the force vertically into the sound board giving the required down pressure on the top.

    • Like 1

  12. Running a tube amp off of a variac and turning down the voltage is NOT a good idea at all!

    While you are reducing the voltage on the amplifier tubes which will indeed give you lower output power you are also reducing the voltage on the tube heater supply which is usually designed to run at nominally 6.3 volts or 12.6 volts +/- 10 % depending on how the heater supply is configured. Reducing the heater supply below its lower limit will reduce your tubes life and accidentally increasing it above the upper limit will most definitely destroy the heater coil.

  13. Ground loops inside guitars are somewhat overrated. Hum and noise are directly proportional to the current in a circuit NOT the voltage. In a guitar the currents are to low to really be a problem for ground loops. Amplifiers where you have several hundred volts (tube/valve) or lower voltages and lots of amps in the solid state case ground loops become much more important. A few volts potential difference between ground points will result in current flow and the resultant hum.

    Shielding inside guitars is more important than worrying to much about loops

  14. I am finding this threads comments by "Stiffy" more and more objectionable as well as incoherent!

    If English is not your native language then please say so. We then might be able to help you but you are coming across as a complete moron who looks like they are just trying to cause trouble.

  15. "oh, everyone's getting rid of Horse Power, because its not an accurate measurement now. Everything's being converted to ccs."

    What utter balderdash! Salesman will say anything.

    Horse Power is a very precise unit of measurement it just that it's the old Imperial system or whatever you guys call it in the USA.

    Watts is the correct SI unit for power and generally KiloWatts is used.

    CC's is cubic centimetres a measure of volume which is also a bit archaic. The accepted measurement is Litres which is 1000 cubic centimetres.

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