The Ekdahl FAR - Bowing jack: Difference between revisions

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The entire ''bowing jack'' is riding on an ''axle bolt'' so that it can move up and down. Below the ''bowing jack'' to the side is the ''pressure motor'', this has a ''corkscrew'' attached to its output shaft which is responsible for pushing the ''bowing jack'' up and down. Through this mechanism the ''bowing wheel'' can be moved ~4mm / 3/16" up and down by sending the instruments the various ''pressure''-commands.

The ''bowing jack'' can theoretically be controlled with ~0.625ɥm precision, this is of course nuts and probably not true in the real world - but, very small movements in the ''bowing jack''s position does indeed make quite the difference which adds great complexity.

== Adjusting the bowing jack ==

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The ''pressure motor'' is fastened with two ''carriage screws'', these can be accessed without removing the shield by using the long end of a 3mm [[wikipedia:Hex_key|hex key]]. Carefully loosen the screws just enough so that you can slide the carriage, by not removing the hex key from the last screw head you can use it to carefully slide the ''pressure motor'' without removing the shield. As a rule of thumb, the ''bowing wheel'' should be ~1mm below the string at its lowest position. Remember that different wheels have different ''pressure'' properties, a new completely round wheel is generally a good reference candidate. Using the latter when you set the ''pressure motor''s position, most other ''bowing wheels'' should be able to have a full reach without having to move the ''pressure motor'' again.

Be very careful to not over-tighten the ''carriage screws'' as this will strip the threads from the brackets holding the ''pressure motor''.

===== Bowing jack vibrations =====

A major issue when developing the Ekdahl FAR was to find and minimize any vibrations in the instrument as these will create unwanted resonances that will travel through the pickup and create ill sounds. Because the ''bowing wheel'' is running at very high speeds the centrifugal forces makes this quite a challenge. Even with a well-balanced ''bowing wheel'' there will be ''resonant peaks'' in the ''bowing motors'' frequency range.

If this becomes an issue that is not solved by changing to a fresh ''bowing wheel'', the ''bowing jack axle bolt'' can be adjusted. The ''bowing jack'' is suspended on the ''axle bolt'' using [[wikipedia:Thrust_bearing|thrust bearings]] and rubber washers, resonances can be lowered by adjusting how tightly the bolt is holding the ''bowing jack'' against the bearings. This will have to be done by ear, meaning tightening and loosening the bolt while playing the offensive frequencies while also making sure that no new ''resonant peaks'' are created. It is recommended that this is first done without a ''bowing wheel'' on the ''wheel holder'', once this has been done the same procedure can be done with a ''bowing wheel'' attached (but not touching the string).

{{docnav

|[[The Ekdahl FAR - Bowing wheels|Bowing wheels]]

|[[The Ekdahl FAR - Mute|The mute]]

}}

@@ Line 11: / Line 11: @@
 The entire ''bowing jack'' is riding on an ''axle bolt'' so that it can move up and down. Below the ''bowing jack'' to the side is the ''pressure motor'', this has a ''corkscrew'' attached to its output shaft which is responsible for pushing the ''bowing jack'' up and down. Through this mechanism the ''bowing wheel'' can be moved ~4mm / 3/16"  up and down by sending the instruments the various ''pressure''-commands.
+The ''bowing jack'' can <u>theoretically</u> be controlled with ~0.625ɥm precision, this is of course nuts and probably not true in the real world - <u>but,</u> very small movements in the ''bowing jack''s position does indeed make quite the difference which adds great complexity.
 == Adjusting the bowing jack ==
@@ Line 19: / Line 21: @@
 The ''pressure motor'' is fastened with two ''carriage screws'', these can be accessed without removing the shield by using the long end of a 3mm [[wikipedia:Hex_key|hex key]]. Carefully loosen the screws <u>just enough so that you can slide the carriage</u>, by not removing the hex key from the last screw head you can use it to <u>carefully</u> slide the ''pressure motor'' without removing the shield. As a rule of thumb, the ''bowing wheel'' should be ~1mm below the string at its lowest position. Remember that different wheels have different ''pressure'' properties, a new completely round wheel is generally a good reference candidate. Using the latter when you set the ''pressure motor''s position, <u>most</u> other ''bowing wheels'' should be able to have a full reach without having to move the ''pressure motor'' again.
+<u>Be very careful to not over-tighten the ''carriage screws''</u> as this <u>will</u> strip the threads from the brackets holding the ''pressure motor''.
+===== Bowing jack vibrations =====
+A major issue when developing the Ekdahl FAR was to find and minimize any vibrations in the instrument as these will create unwanted resonances that will travel through the pickup and create ill sounds. Because the ''bowing wheel'' is running at very high speeds the centrifugal forces makes this quite a challenge. Even with a well-balanced ''bowing wheel'' there will be ''resonant peaks'' in the ''bowing motors'' frequency range.
+If this becomes an issue that is not solved by changing to a fresh ''bowing wheel'', the ''bowing jack axle bolt'' can be adjusted. The ''bowing jack'' is suspended on the ''axle bolt'' using [[wikipedia:Thrust_bearing|thrust bearings]] and rubber washers, resonances can be lowered by adjusting how tightly the bolt is holding the ''bowing jack'' against the bearings. This will have to be done by ear, meaning tightening and loosening the bolt while playing the offensive frequencies while also making sure that no new ''resonant peaks'' are created. It is recommended that this is first done without a ''bowing wheel'' on the ''wheel holder'', once this has been done the same procedure can be done with a ''bowing wheel'' attached (but not touching the string).
+{{docnav
+|[[The Ekdahl FAR - Bowing wheels|Bowing wheels]]
+|[[The Ekdahl FAR - Mute|The mute]]
+}}