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Has anyone made a Torzal tist-like neck?

#21
Here's a MCP (manually controlled pen) pic of the jig. Rails are steel tubes. Rails are tapered along neck sides. Bridge end will be horizontal, nut end will be around 15 deg from horizontal.
Router will be mounted to a some kind of a sled that glides along the rails. Routing will be done along string paths.
Page0001-1.jpg

Marko
 
#26
Hi.

MPU said:
Here's a MCP (manually controlled pen) pic of the jig. Rails are steel tubes. Rails are tapered along neck sides. Bridge end will be horizontal, nut end will be around 15 deg from horizontal.
Router will be mounted to a some kind of a sled that glides along the rails. Routing will be done along string paths.
Page0001-1.jpg

Marko
Click to expand...

I would (and will ;)) make the ends the same, and put a pivot point in the middle of the anchor plates, so the angle of the rotation can be controlled in both ends.

The carriage will have easily removable radius blocks for different FB radiuses as well.

Regards
Sam
 
#27
How are you figuring the carriage attachment? Consider that the distance between the rails varies along its length.

It's a bit more complex than it may seem at first. I see you having a two-block attachment to one rail, with a floating (sliding) contact with the other rail. Then you'd have to put a transverse sliding carriage on top. You'd keep the motion perpendicular to the first rail, to do somewhat if an approximation to a try helix.
 
#28
I still have not decided whether the rails are tapered or parallel. For router jig I was thinking that the lower string side will have two contact points to the rail and the higher string side will have only one contact point. If I could get close enough results with routing just along the neck center line there would be no problems making this neck. If I have to route along the string paths I have to figure out some kind of side guide for the router. I'm thinking about using the 8mm side guide holes on the router base as some kind of mountings for the sled. Maybe just two 8mm steel rods will work out fine. I'll have to try and see. This time I really have to do some test routings before I start routing the real neck.
Marko
 
#29
Ok, I hear you. But part of my point was - well first let my clarify. I'm assuming that when you talk about the rails not being tapered, you mean being the same distance apart at the two end anchorages. The problem is that this still does not make them the same distance apart along their full length. They are still closer together at their centers.

This is because the two lines are skew in 3d space, are not coplanar.

Imagine this thought experiment. Start with two rails, dead parallel. Now twist one pair of ends (while keeping the other ends fixed). You can do this either by rotating both tips around an imaginary center point between them, or by holding one tip fixed and moving the other in a circular arc around it. Either method keeps these two tips at a fixed distance to each other. But, you'll see as you get to 180 degrees of sweep, the rails cross each other and make an "X". There is zero distance between them.

The problem, then, is that as you went from 0 to 180 degrees rotation, the distance between rails at their middle parts was gradually decreasing. With any twist at all, the midlength separation is less than the end separation.

Hence the need to have a carriage that will allow for this, by not fixedly attaching to the second rail. There's got to be some kind of sliding action, or other compensation.
 
#30
Now I understand what you ment. Thanks for clarifying (english is not my native language so please be patient and try to understand what I'm trying to say).
What if I used something like the side guide on the router on the rods so that rods glide on top of the rails and the side guide would glide along the side of the lower string rail and keep the router parallel to the rail? The other ends of the rods (or just one rod) would glide along the top of the second rail. Then I'd just move the side guide when I need to move the router sideways.
Marko
 
#36
The twist-neck bass has been officially started. I made a 9-piece laminated maple neck blank and routed the twist today. I also routed the truss rod slot and at the moment the neck is under vacuum for 0,5mm layer of carbon fiber under the fretboard. I also saw and thicknessed an ebony fretboard for two 2mm veneers. I'm planning to mark the fret lines before laminating the fretboard to the neck. Fret slots will be sawn after the neck is tapered. At the moment I've not decided if I'm skinning the back of the neck with carbon fiber as well. Neck profile will be Rick Toone's TNP once again.
Body will be quite smallish and curved to fit as ergonomic as possible.
No pics, sorry. Maybe tomorrow.
Marko
 
#37
MPU said:
Test run done. I changed the router to a smaller base one. Jig works just fine.
Marko

torzmock.jpg
Click to expand...
I'd suggest that you suspend a straightedge about a millimeter above what would become the actual string paths, and and check for a consistent 1 mm gap along its length. This would confirm that your jig and method will be able to produce a neck that can be set up properly.
 
#38
I checked the string paths before carbon fiber laminating. Some very, very slight passes with scraper were needed in B and G string paths. B path had a bit too much in the middle, G path a bit too much at the nut end. I'm going to check the paths along the neck build to make sure they stay straight.
Marko
 

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