View Full Version : More Lathe work

05-23-2009, 06:35 AM
One job I hated doing is "radiusing the tail/neck blocks" I did use to do it with a form covered with sand paper, and I rubbed and sanded the blocks down until I got a decent fit but ...But now I've made this device for the lathe it's no problem at all and I can make lots together and just take one off the shelf when a need one and know it will fit without sanding..
Here it is in the lathe and loaded up with blank tail blocks.
One single pass at high rev's (I hope they don't fly out) total machining time 24 seconds...I recon I can radius 8 every 5 min's like this ..thats 96 per hour..I don't need that many.
Well I must say..That was easy! peasy! and all turned out perfect.

05-23-2009, 12:49 PM
Hehe well laziness is the source of many new inventions and methods.. What a great idea Tim and thank you for sharing :)

05-23-2009, 06:09 PM
Nice! Always like to see new ideas. :cool:

05-23-2009, 06:43 PM
That is just freakishly clever! You're a genius! :bowdown:

05-23-2009, 08:24 PM
Nice job Timbuck. Your process is definately more efficient in output than mine but at least I did solve the issue of getting a perfect fit without the need to sand. Here is a cut and paste from a post I had at UkeTalk a while back. This may be useful for those that don't have access to a lathe.

There are some things about the building process that you just can’t speed up. And there are those other tasks that seem tedious with variable results. Shaping the neck heel and tail blocks to conform to the curvature of the body is one of those small but dreaded elements that I never look forward too. I know that some builders just make their molds so they are flat at both the heel and tail but I prefer to preserve a shape that is a bit more true to the original Martin shapes.

I have the Ken Potts video where he shows how he “eyeballs” the space between the body and the block, transfers this to the block, and pencils in a sanding line. He rolls it back and forth over the belt sander and claims that eventually you just get the hang of it. Well, for my first 6 or so builds I could never get the hang of it so I decided to try something similar to what I remember seeing Mike DaSilva do back when he was in his small single care workshop.

Mike used a disc sander and a jig to shape his heels. Everytime I messed up a block I would tell myself I needed to make a jig like Mike’s. I finally threw together a quick jig for this purpose and it works great and makes this process a breeze. I actually made the jig a couple of years ago and have used it on the last two tenors and a couple of sopranos I'm finishing now.

It’s just a T fence that mounts to the table of the disc sander. A trammel is used to pivot on a ¼” dowel at the correct distance from the sander that will create the matching curve. To do that I just used a long scrap piece of particle board and using the molds I traced the curve near the end of the particle board. Then I had a 3/8” wide strip of wood that I drilled a small hole in the end to look through. Then by trial and error I just drilled small holes at the other end of the stick for a brad to fit in and sited through the hole until it matched as I pivoted the stick across the board. That would be the distance I would use to make my permanent trammel for the jig.

Here are a few pics. You rotate the work against the rotation of the sander. One pass is all it takes and it will conform to you mold beautifully.

The block is just screwed on from the bottom
Overall Setup
Feed into/against the rotation of the disc
Nice curve after one pass

05-23-2009, 10:14 PM
That method or something like it did cross my mind...If I didn't have the Lathe, thats more or less how I would have done it...Only I would have done it on the belt sander (raised into it's vertical position) as sanding discs wear out faster than the belts due to the smaller surface area.
Great pic's ..keep sharing ideas.:music:
Anyway I've fitted one into the next uke no sanding just glued it right in ..and the fits pretty good...so the calculations were ok.

Pete Howlett
05-24-2009, 12:03 PM
Great ideas if you have a known radius to work to....

E-Lo Roberts
05-24-2009, 03:54 PM
Thanks Tim and Dom for some clever solutions to this problem. Now you got me re-thinking my approach!...e.lo...

05-24-2009, 11:57 PM
It's simple to obtain the radius from an arc drawn from the mould inc: centreline .... then just intersect the points of the arc like this to give dimension X = rad...and dont forget to take off the thickness of the side material.

05-25-2009, 12:05 AM
Double posted..IGNORE

Pete Howlett
05-25-2009, 07:23 AM
Thanks Ken - I know my soprano radius - its 20" and I have tools to create that but this will really help with the neck block profile. Never did trig at school and was totally hopeless at mathematics. You have the benefit of a practical engineering background. Most of us builders are self taught and learn things kinesthetically - like this....:smileybounce:

Moore Bettah Ukuleles
05-25-2009, 08:00 AM
Not to belittle anyone else's methods, it's always interesting to see how other people do things, but I'm in Ken Potts' camp with this one. I don't get how doing this by hand is considered being so hard. When compared to scores of other procedures that must be done by hand, fashioning the tail block is a breeze.
Anyway, if I had a big lathe like like they'd be calling me Two-Fingered Charlie or One-Eye Jack within a week!

Pete Howlett
05-25-2009, 02:09 PM

In defense of Ken - he is an engineer and like Bill Collings who has a similar background is forever finding ways of making a machine do, what for us, is bread and butter hand work... I don't necessarily agree with Ken's methods or the results (a semi circular neck profile is not for me) but you gotta admit, it's genius at work stuff. And if you think he's not up to it, see his 'Island build' experiment, Nunes/Diaz/Kumalae style. He's no slouch...

Moore Bettah Ukuleles
05-25-2009, 02:37 PM
Come on Pete, I'm not getting down on anyone. Re read my first sentence. Ken doesn't need anyone to defend him, what he does speaks for itself. All I'm saying is that for me sanding the curve on a tail block takes no time at all and that there are a lot of other procedures that take far more skill, getting a perfect neck to body joint for instance. I'm also terrified of large spinning machinery.

Pete Howlett
05-25-2009, 05:51 PM
I'm not having a pop - just saying there is more to Ken than his genius methods of doing jobs us hand builders find as no-brainers.

And yes, there are too many bits to that jig to fly off for my liking; plus the 'interrupted' cut :eek:

Speaking of neck joints, what do you use on your instruments Chuck? I used to use a spline but now use a bolt. I'm considering going back to dovetails...

05-27-2009, 09:31 PM
At first glance, I thought that thing was a jig to hold the uke body in. I was thinking you're crazy for sticking a half finished body on the lathe. Then, I read the post and saw the other pictures. That is definitely a cool way to turn out a bunch of blocks quickly and efficiently.

I both love and hate doing things by hand. Since most of my day is devoted to keeping the production line going, I'm always looking for ways to jig up, simplify, or dumb down a process. I've had new guys ruin a run of parts, when all you have to to do is push a button on the laser. Thankfully, no one has severed any body parts, except me and Pops. I love getting deeply involved with my custom builds, but I always have the pressure of production in the back of my mind. I end up rushing, making mistakes, and having to do it again, or spend thrice the amount of time fixing it. If everything goes well during the build, I'll probably drop it when I buff. Thus, I love doing things old school, but not under the pressure of having multiple hats.

Like Chuck, I'm terrified at the thought of using a lathe. Although I've always wanted one, I'm plain freaked out by them. Table saw accidents set aside, I've been hurt by the drill press more than any other tool in the shop. Something about rotational axis' and me don't mix.

05-27-2009, 09:49 PM
Thankfully, no one has severed any body parts, except me and Pops.

You've lost a body part? :eek:

Which one?

Pete Howlett
05-28-2009, 05:14 AM
Accidents - 1 with a power drill chuck key - not serious; 3 with a table saw - one serious requiring reconstructive surgery; 1 with a hammer - ouch! and I had a gig the same night so I had to learn how to use 3 fingers to chord pretty darn quick... and countless ones with a bending iron - I must remember to use a long sleeve shirt when I am and bending!

I'd say for a production shop without CNC, Ken's lathe method for end-blocks would be great idea were it not for health and safety issues. Such set-ups are OK in a one man shop.

And Paul, I am with you on the really important custom jobs where your back is against the wall - there is always an anti-workshop imp screwing around with you and the progress to get it finished.

May I just take this opportunity to say how good the debate is on this forum - it is measured and with the right amount of 'intellectual' input keeping it on topic.