Double Bass Endpin Socket Taper?

[robobass]

I wonder if you could set up the lathe by chucking the endpin reamer and running a dial gage along it.

Excellent idea! Hadn't thought of that.

 

[robobass]

We made a run of bass endpins using delrin as the plug material and never had a problem with not having enough friction between the plug and the spruce block. I remember leaving the turned finish a little more coarse and also hitting it with rough sandpaper thinking that would help. But I'm not sure it makes much difference really if the fit is good. The nicer endpins that Shen supplies for example use what looks like nylon for the plug and those seem to work fine.

I'm sure Rob knows all this but one thing that has helped me when turning tapers on a lathe is to either turn between centers or use a nominal dimension on one side so that side can be held in a collet. That way you can remove the piece and check the fit without losing concentricity as you put it back in.

Another thing that helps me is to mark out two marks along the taper with an inch (or any set distance) between. Measure the diameters and subtract the difference. Even as you decrease in diameter overall this difference in diameters amounts to your taper, and you use that to adjust the the machine. Cosign error here but it doesn't matter as you're just using the figure for fitting purposes.

Using the compound rest is the toughest way to make fine adjustments for sure. Turning between centers is less finicky but I have a taper attachment for my Clausing 5900 lathe and that's the slickest way for me. I do have a small wood lathe but I still go back to metal lathe for this kind of thing.

I don't understand "turning between centers" I have a live center, if that's what you mean. Also, my lathe is fairly small so the compound won't traverse the entire length needed. I see this not as a huge inconvenience, as once the angle is set correctly, I only need to reposition the carriage once. This job really calls out for a 4 axis CNC, though. Especially considering the threading. Once I have a good proto, I might just job out the production. I'm relearning CadCam and looking at a 3 axis router. Amazing how cheap they've gotten, but 4+ axis is still pretty pricey. For both software and hardware!

 

[fdeck]

vejesse knows this stuff better than I do, but AFAIK "between centers" means there are centers on both the spindle and tailstock. Something is needed to turn the workpiece, either a toothed center for woodworking or a lathe dog for metalworking. And then you can turn a taper by offsetting the tailstock.

I'm not a trained machinist, but somewhat of a tool maker and millwright. I'm interested in archaic techniques out of pure curiosity, but also because a dive into the past can often uncover an idea that solves a problem without expensive machinery such as a 4-axis mill. The inexpensive CNC stuff tends to be rickety, from what I've seen. In the past, a lot of work done in smaller shops used general purpose machines with custom jigs and fixtures. That's a way to extend the machine's capability without huge investment. And the jigs can often be made from wood, using common tools.

Also, designs would be chosen that could be made using the technology at hand, or with custom tools like shaped lathe cutters.

Case in point, I don't even own a drill press. The enclosures for my HPF-Pre are drilled using a wooden jig with hardened steel drill bushings and two hand drills. One drill spots all of the holes. The other one has a "uni-bit" and handles all 5 diameters that I need. I can crank out boxes like nobody's business, and my equipment investment is minimal.

It's more efficient for a full service shop to have CNC's than to create custom jigs for every job, but the typical production shop may only make a small handful of different parts ever.

 

[robobass]

vejesse knows this stuff better than I do, but AFAIK "between centers" means there are centers on both the spindle and tailstock. Something is needed to turn the workpiece, either a toothed center for woodworking or a lathe dog for metalworking. And then you can turn a taper by offsetting the tailstock.

I'm not a trained machinist, but somewhat of a tool maker and millwright. I'm interested in archaic techniques out of pure curiosity, but also because a dive into the past can often uncover an idea that solves a problem without expensive machinery such as a 4-axis mill. The inexpensive CNC stuff tends to be rickety, from what I've seen. In the past, a lot of work done in smaller shops used general purpose machines with custom jigs and fixtures. That's a way to extend the machine's capability without huge investment. And the jigs can often be made from wood, using common tools.

Also, designs would be chosen that could be made using the technology at hand, or with custom tools like shaped lathe cutters.

Case in point, I don't even own a drill press. The enclosures for my HPF-Pre are drilled using a wooden jig with hardened steel drill bushings and two hand drills. One drill spots all of the holes. The other one has a "uni-bit" and handles all 5 diameters that I need. I can crank out boxes like nobody's business, and my equipment investment is minimal.

It's more efficient for a full service shop to have CNC's than to create custom jigs for every job, but the typical production shop may only make a small handful of different parts ever.

you can turn a taper by offsetting the tailstock.
Interesting. I've never seen this. Is it something more in the domain of wood lathes? I don't know how I'd offset my tailstock.

As to traditional machines and jigs vs. CNC, I suppose it depends on what you're doing. My capos are currently done with standard machines except for water jet to cut the outlines on the E-Stop. I grind the rounded surface on the Capo yoke on a belt sander. That's the main reason I'm setting up a CNC router. I've done that job by hand a few thousand times now, and am pretty tired of it! There's the incessant noise of the router, and frustration of CadCam programming, but there are also many advantages. I did packaging models in the 90's in a non-CNC shop where we often had to make ellipses. On a knee mill with a rotary table you can get the job done perfectly well, but it means repositioning the work 3 times and can take half a day. Nobody's going to pay for that any more when with CNC you can do it with a few mouse clicks!

 

[RCWilliams]

Robobass, if you are going to invest in a cnc make sure you get one robust enough to handle the work, and large enough to handle the largest project you can imagine you would want to do. the fourth axis will make the threading and tapers much easier. I made my own out of a super spacer and a servo motor, makes machining necks and many other things much easier.

 

[james condino]

No drill press!!!!??????!!!! 'Tony and the rest of those old school fellows in Cremona did just fine without one.....

j.
www.condino.com

 

[KBass]

When I reconstructed my bass I had a good endpin which I'm still using but the hole was distorted. Not having and end pin reamer I drilled out the end block with a Forstner bit, I think at 2" dia or so. I used an adjustable cutter and cut a succession of holes, that corresponded to the 1:17 ratio of the end pin taper, in a sheet of 1/4" plywood on 2 1/2 centers using a drill press. I then drilled out a series of rings with an OD of 2" to fit in the end block. See the photos. I stacked them up and glued them into the endblock and followed up with screws to keep everything in place. The photos are self explanatory, really.

 

[james condino]

That looks like it will work.

Many of the violin parts specialty places sell tapered plugs to rebuild an endpin hole for under $10. I used to spend a lot of time trying to get the hole to fit the endpin. It was a great day when I got a decent lathe in the shop and started buying oversized endpins and then chucking it up on the lathe and turning the endpin down to match the existing hole. Most of the time I do it while the customer is watching- they dig the old school machinist vibe. A creative person could do the same with threaded bolt securing the endpin and then chuck it up in a drill press; even better if I had an old Bridgeport mill. Keirin- how's that new one treating you????

I know it is an old thread and old post but....

Rob: On better lathes, and in particular patternmaker style wood lathes, you can offset the taper of both the headstock and tailstock to make tapers. I recently got rid of myold Walker Turner lathe and upgraded to a giant old Oliver patternmaker lathe because it has the ability over the bed and something like 84" on the outside...!

 

[KBass]

Thanks. It works great and the block is much sturdier with the homemade collar in it. That has been my main bass for the last 6 to 8 years. It's my opinion after 51 years of playing basses and fixing them that neck and end blocks should not be made from spruce. They are main structural elements and I've had split neck blocks and worn out end block holes to deal with. I think they should be machined from high layer count plywood. Not as difficult as maple and much stronger than spruce.

Should I post my bolt-on neck-work on the same bass? Again this bass has held up beautifully since I did all this work at the same time.

Right now I'm resurrecting my plywood bass and my 1827 Seitz along with 2 others waiting in the wings.

Where do I get an oversized endpin in carbon fiber that's not stupid expensive? I need 31.6 mm at the fat end of the taper.

Just ordered a reamer and I now have a pair of china CF endpins which have too small a taper to work. I don't want to do this again but I'm thinking about it. Once I have a reamer this will be a lot easier to do.

And just for poops and giggles I'm putting on a carbon fiber fingerboard on the plywood. Actually I just like the idea of them not wearing from the strings. I've not seen a lot of posts about that. If anyone wants to direct me to CF fingerboards.

Thank you for your response.

 

[robobass]

Rob: On better lathes, and in particular patternmaker style wood lathes, you can offset the taper of both the headstock and tailstock to make tapers. I recently got rid of myold Walker Turner lathe and upgraded to a giant old Oliver patternmaker lathe because it has the ability over the bed and something like 84" on the outside...!

James,
Thanks. I have no experience with wood lathes. I have mostly solved the problem by matching the compound angle to a reamer using a dial indicator. Even this method is not without issues, but much of it is probably because my machine lathe has seen hard use and was not the highest quality in the first place. I made some replacement Laborie pins and it still took a bit of fine sanding to get them fitted perfectly. I know that machining wood is never going to be as precise as cutting metal, but I'm still astounded by the crappy tolerances I find on sockets. I suppose the only way to do it right is to do what you do, and re-cut the taper yourself.

 

[RCWilliams]

Match your reamer to the taper with one of these. this one fits a laborie style pin, about 19mm dia at the top