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Nov 29, 2022 - 6:47:12 PM
59 posts since 4/13/2004

Guys, I know this has come up before, but half of the discussions on the subject comes with a boat load of deleted Photo Bucket pictures. Here is my issue. I am putting together a jig for cutting the one-piece flange shape on the neck. The one question I have is how do I get the distance between the dremel style cutter and the neck to match the curve on the rim. There is nothing on the one piece flange cut on the rim that comes to 11". I plan to sweep the rotary tool across the neck. I have the ability to raise and lower the cutting tool as well as go forward and reverse to follow the template traced on the neck. The neck will be anchored on a table, upside down, resting on its fretboard.
My thought for now is to get 5.5" sweep to the table holding the neck, then hopefully everything else takes care of itself for the different cuts. However, I don't know if there are other factors to consider.
Any insight on this would be much appreciated.
Patrick

Nov 30, 2022 - 2:19:51 AM
Players Union Member

Helix

USA

16373 posts since 8/30/2006

What kind of a jig?
I tried 5.5" radius.
I prefer 5" because it snugs up to the rim.
I lay my neck frets down and wedge back up to 90 degrees and clamp.

Nov 30, 2022 - 3:53:18 AM
likes this

5082 posts since 11/20/2004

On a banjo with a Mastertone style tone ring, the upper neck pad sits against the ring, which is an 11" radius. The other contact points are lesser. Using a smaller radius ensures the sides of the neck make solid contact for more stability and less side to side rock. I usually find a little hand sanding is needed for fitting to my satisfaction and best contact.

Nov 30, 2022 - 5:30:02 AM

545 posts since 11/9/2021

LOL - I was expecting a tune, "Banjo Neck Fitting Jig" !! Not a very catchy name, but very descriptive.

Nov 30, 2022 - 6:25:15 AM

10287 posts since 8/28/2013

quote:
Originally posted by wrench13

LOL - I was expecting a tune, "Banjo Neck Fitting Jig" !! Not a very catchy name, but very descriptive.


This thread is in the wrong forum. "Banjo Neck Fitting Jig" should be in the forum for Irish Trad.

Nov 30, 2022 - 6:58:50 AM
like this

718 posts since 7/10/2012

I recently built a(nother) neck jig based on a design I saw rendered by RedArrowRyan and it is working pretty well for me so far. One of the tricks is that, in addition to the cutter being able to swing at a variety of diameter sweeps, it also has to be adjustable up and down and either the neck or the cutter needs to be able to move toward the other to get the bigger diameter for the tension hoop cut as well as, in your case, the flange cut.  I opted to have the neck slide, rather than the cutter, on a rail I made from a piece of brass I usually use to make rolled bar tone rings.  I have the router mounted on a scissor table for the vertical adjustment that also has a platform bolted though the center of the table for the rotation you need to make the heel cut and walls to clamp to the router once I establish the correct diameter I need.  

Here is a pic of the jig:

Note the brass bar sticking out from below the box holding the neck.  There is a trough on the underside of the box that fits over the brass bar, enabling the box to move toward the cutter.

The top of the box has a center line that you have to establish through a bit of trial and error to make sure it is dead on.  I align the center of the neck at the cutter end to that line and the third fret slot at the other end:

Then I make sure the angle of the neck is set where I want it by adjusting the placement of a pair of dowels and using a digital angle finder:

I set the diameter of the cut by measuring the radius from the pivot point on the router table with a square.  I slide the router forward until the tip of the bit is the correct distance from the center pivot to cut at the right diameter, e.g. 5.5" for an 11" diameter, and I clamp the walls to pinch the router tight:

Then I slide the neck toward the router and make the cut, lowering the router for each pass and then sliding the neck a bit closer for the next depth pass.  I make the final tension hoop cut by adjusting the diameter by a few mm toward the neck to get a larger arc:

Once the cut is made, I test the alignment against the pot with a very complex technical method based on String Theory:

I also found that, with the neck still clamped in place on the jig, I can use the same set up to route a 1/4" channel into the pot facing side of the heel for the neck-to-rim anchor and, with the neck box removed from the jig and placed on the drill press table I can drill into the top of the heel for the Rudy Rod insert, which I cover with a heel cap:

I hope all that's helpful, good luck with your jig!

David

Nov 30, 2022 - 8:34:46 AM
Players Union Member

Helix

USA

16373 posts since 8/30/2006

Very fine

Nov 30, 2022 - 9:34:16 AM

718 posts since 7/10/2012

Thanks Larry, I can't take credit of course. Standing on the shoulders of my betters ( RedArrowRyan ).

David

Nov 30, 2022 - 11:49:58 AM

Fathand

Canada

12090 posts since 2/7/2008

I use this horrible looking jig that mounts to my milling machine table and pivots the neck heel against a drum sander or router bit. I just dial the table feed to the correct radius.

A dremel or rotary tool is going to be seriously underpowered I think. A $69 trim router will do the job admirably and has dozens of applications in building instruments.


 

Dec 1, 2022 - 11:50:34 AM

pfolmar

USA

59 posts since 4/13/2004

Thanks dpgetman, you saved me from making one mistake. I need to bring the neck to the cutting tool in order to maintain the proper cutting radius. I will use a small turnstile to swivel the router for the 11" arc. I don't see any turnstile in your pictures for swivelling the router across the neck. I plan to connect the router to a small turnstile on a scissor table so I can swivel the router side to side. The scissor table will let me move the router up and down-very similar to your pictures. However, I have a completely different solution for securing the neck during the cutting operation. As soon as I put it together, I'll send some pictures.

Dec 1, 2022 - 2:52:29 PM

718 posts since 7/10/2012

quote:
Originally posted by pfolmar

Thanks dpgetman, you saved me from making one mistake. I need to bring the neck to the cutting tool in order to maintain the proper cutting radius. I will use a small turnstile to swivel the router for the 11" arc. I don't see any turnstile in your pictures for swivelling the router across the neck. I plan to connect the router to a small turnstile on a scissor table so I can swivel the router side to side. The scissor table will let me move the router up and down-very similar to your pictures. However, I have a completely different solution for securing the neck during the cutting operation. As soon as I put it together, I'll send some pictures.


I'm not sure what you mean by turnstile, but in the jig I made, the box that holds the router has a bolt through the middle of the bottom that also passes through the middle of the scissor table.  The router box holding the router spins on that axis, which also serves as the center of the circle to measure the diameter.  

Dec 2, 2022 - 6:56:13 PM

2939 posts since 2/12/2005

I remember seeing a machine for a one-piece flange neck cut.

It was made from a drill press which was spinning a sandwich of three MDF disks. The sizes of the disks corresponded to the curves needed on the level different areas where a neck touches a pot assembly.

Each disk had sandpaper on it. There were bearings under the disks to take a side load on the disks without putting (much) force on the shaft coming from the drill press motor.

The luthier had a device to hold the neck that was lined up to the centerpoint of the disks. It controlled the angle of the neck and that aspect was adjustable. He could lift the neck a bit for fine control of the results.

He would push the neck forward into the sandpaper and wood was removed.

I only saw it used to reset an existing neck which was already basically the right shape. He was a famous neck maker and I think he had a different machine to rough out that neck area.

Maybe this machine was just for the finishing passes (and recuts).

Dec 3, 2022 - 7:03:46 AM

2939 posts since 2/12/2005

I found this video of a similar machine. Ritchie's machine only does one surface at a time (I think). The one I saw in Hendersonville did all the surfaces simultaneously.

(I give Hendersonville as a hint for those of you who know your luthiers.)

Dec 3, 2022 - 5:47:22 PM

718 posts since 7/10/2012

quote:
Originally posted by randybartlett

I remember seeing a machine for a one-piece flange neck cut.

It was made from a drill press which was spinning a sandwich of three MDF disks. The sizes of the disks corresponded to the curves needed on the level different areas where a neck touches a pot assembly.

Each disk had sandpaper on it. There were bearings under the disks to take a side load on the disks without putting (much) force on the shaft coming from the drill press motor.

The luthier had a device to hold the neck that was lined up to the centerpoint of the disks. It controlled the angle of the neck and that aspect was adjustable. He could lift the neck a bit for fine control of the results.

He would push the neck forward into the sandpaper and wood was removed.

I only saw it used to reset an existing neck which was already basically the right shape. He was a famous neck maker and I think he had a different machine to rough out that neck area.

Maybe this machine was just for the finishing passes (and recuts).


You know, I actually made one of these stacked disc sanding machine.  I also made two other sleds that fed into my drum sander.  What I realized was that, no matter how securely I clamped everything into place, the friction of the sandpaper against the wood or the flexibility of the drum or something tended to skew either the diameter or the angles.  What I like about the router jig is that the cutter removes wood so quickly and efficiently that the neck stays in place without any micro-movements during the process.  Just my two cents... 

Dec 3, 2022 - 6:08:04 PM

pfolmar

USA

59 posts since 4/13/2004

Randy, is that Hendersonville NC or Hendersonville TN. I live in Hendersonville, NC myself. Also, you said you have a video. Is there any way you can share that with us?

Dec 3, 2022 - 8:24:29 PM

2939 posts since 2/12/2005

quote:
Originally posted by pfolmar

Randy, is that Hendersonville NC or Hendersonville TN. I live in Hendersonville, NC myself. Also, you said you have a video. Is there any way you can share that with us?


I meant to post this URL.  It's not long but you get the idea.

https://www.youtube.com/watch?v=fd7jiE1ciOs

Hendersonville TN, but (2nd clue) not Huber.  He was Huber''s neighbor.

Jan 21, 2023 - 2:38:44 PM

pfolmar

USA

59 posts since 4/13/2004

Hello everyone. Thanks for your feed back on putting together a neck fitting jig. I finally got my jig completed and did my first neck. There are some things I would do different upon reflection, but here are some pictures. The next refinement would be to keep the neck relatively stationary in the forward to back direction and be able to have router go forward or reverse to the neck. The parts of the neck cuts that are relative to the tension hoop, the flange/tone ring & the rim are all a little different radius, so I had to change how far the router stuck out from its clamped position. All the parts were purchased on amazon.com, including the $40 router. I also purchased an inexpensive laser leveler not pictured because I was worried the neck would not intersect the router perfectly in line. It was a good thing, too, because I did need to make a few adjustments. Any other ideas will certain be welcomed.
Patrick


Jan 23, 2023 - 4:32:23 AM
Players Union Member

Helix

USA

16373 posts since 8/30/2006

You did really good already. I like the incline-o-meter on the heel.

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