3d printed bobbins

[Lyrebird Steve]

Couldn't you simply "cut and shunt" a cheap bobbin

Mojotone Humbucker Blade Pickup Bobbin Black

Cut out the part of the middle and epoxy back together ?

For a buck, i'd be trying this

[Sock Puppet]

I found these bobbins at http://www.spelektroniikka.fi/kuvat/koko2008.pdf
In the 2008 catalogue Page 123 - there's much more there.

[Bruce Johnson]

I'll suggest again that you consider casting your bobbins from polyurethane resin. For relatively small numbers, like a few hundred parts, I think that's the least expensive method. It's definitely cheaper than CNC or 3-D printing, and the parts are smooth and tough. I've been making all my pickup bobbins (all my own designs) this way for about 8 years. Basically, you make up a nice Master one time from plastic or aluminum, or whatever. You can hand carve it or CNC cut it, or use whatever machines you have to make it. Then you make silicone molds from the Master. Casting the parts takes less than a minute a piece, and they are cured in 15 minutes. I lay out a row of molds in a row and pour batches of them at a time. Out of the molds, I do a couple of trimming and drilling operations. It's less investment and labor per part than any other method I know of, in this level of quantities.

Here's my (now outdated) set of web pages showing my pickup making process. I've linked it on here before. The molds and casting process are on the first page.

Building Scroll Basses- Pickups 1

[rickmorgan2003]

I'll suggest again that you consider casting your bobbins from polyurethane resin. For relatively small numbers, like a few hundred parts, I think that's the least expensive method. It's definitely cheaper than CNC or 3-D printing, and the parts are smooth and tough. I've been making all my pickup bobbins (all my own designs) this way for about 8 years. Basically, you make up a nice Master one time from plastic or aluminum, or whatever. You can hand carve it or CNC cut it, or use whatever machines you have to make it. Then you make silicone molds from the Master. Casting the parts takes less than a minute a piece, and they are cured in 15 minutes. I lay out a row of molds in a row and pour batches of them at a time. Out of the molds, I do a couple of trimming and drilling operations. It's less investment and labor per part than any other method I know of, in this level of quantities.

Here's my (now outdated) set of web pages showing my pickup making process. I've linked it on here before. The molds and casting process are on the first page.

Building Scroll Basses- Pickups 1

That's a nice operation you got going there. I may try it but one of my goals is to not get into manufacturing all my parts if possible. I don't have the level of equipment you do. I have a very small shop (10X12') with no access to milling machines, pin routers, cnc setup etc. Most of my work is done with small hand tools. Pic is of my daughter wiring up her uke. That's 90% of my shop there For larger sawing operations I go to a shared wood shop space that I rent time at. I have a POS drill press that needs rebuilding if I want to get any accuracy out of it. I am a luthier first. I make pickups because I enjoy it but also because I don't have an economic choice when making electric ukuleles. I totally envy your set up! If I ever get to that point I will probably get lost in the shop for weeks playing with new designs and ideas

[rickmorgan2003]

Couldn't you simply "cut and shunt" a cheap bobbin

Mojotone Humbucker Blade Pickup Bobbin Black

Cut out the part of the middle and epoxy back together ?

For a buck, i'd be trying this

I did order one of those to see if that was feasible but all 3 dimensions were off just enough that I didn't want to go that route. A little to tall and wide.

[Bruce Johnson]

Rick, one point about using the casting process is that you only need to make the master once per design. You can pay someone to machine it for you, or you can make it from hobby shop styrene plastic, on a tabletop with hand tools. Old model car building techniques. The Master can be made out of anything, as long as it's cut to the right shape and smoothed. Plastic, wood, even modeling clay. I use aluminum because I have the machine shop, and I want the Masters to be permanent and durable.

Once you have the Master, all of the casting and trimming can be done with bench top tools. A small drill press is the only power tool you need, for getting neat perpendicular holes. A small bench belt sander is helpful for flattening the backs of the cast parts, but you can also clamp them in a vise and run a file over them. It's just plastic.

What I'm doing in those pages isn't as hard as it looks, and could be done in your shop.

[rickmorgan2003]

What I'm doing in those pages isn't as hard as it looks, and could be done in your shop.

I will give it a shot. Should be easier since I have a blade design this time and that can be cast vs having to drill holes. Do you have a source that you like for poly resin?

[Hugh Evans]

It depends. The term 3D printing leaves many people to erroneously believe they all use the same, or similar, base technology. In reality there are several types in common use: extrusion deposition is effectively synonymous with DIY machines, while selective laser sintering (SLS) and stereolithography are much more common in the high end market. SLS produces parts that are nearly identical to injection molding, with excellent surface finish and strength properties. Stereolithography is found more in niche applications and is highly limited in terms of compatible polymers, because the process requires a stable and translucent solution that is photoreactive to specific wavelengths. They have outstanding dimensional accuracy, produce relatively weak parts, and takes forever to make them. At the professional level, extrusion is getting better all the time. Unless a better method is found, advances at the high end will continue to trickle down to the consumer market and within the next few years I expect we will see large strides in quality and strength. SLS makes better parts, but it's too messy for the average consumer. It would be great to see some become available for the high end hobbyist market.

Back to the definition of expensive: cost for these machines is always a function of maximum part size. Most smaller machines are in the 5-figure range, while larger and more advanced types can reach the low millions.

In case you're wondering how high end SLS compares to injection molded parts: About a decade ago while I was still in engineering school, we had all of the cutting edge rapid prototyping machines at our disposal (including one of the first direct metal deposition machines ever.) Several manufacturers at the time contracted with us to have prototypes printed in higher performance plastics, such as nylon-5, for use in functional test articles... and not wimpy ones. DeWalt was one of our biggest clients, and with a single shot of yellow paint it looked just like a finished part. Technology has come a long way since then.

In my opinion, for pickup bobbins, there's much more bang for your buck to be had with a small CNC router. Even a little dremel based unit with a square foot of cutting area and a couple inches of z-travel could make any bobbin from stronger materials, and with better strength and cosmetic results than a similarly priced 3D printer. Hell, even a drill press and a router table with a few clever jigs would be a lot better.

[Hugh Evans]

Even without access to milling equipment you can full off molding like this by contracting out, especially if you have some CAD ability. I've had very good experience with ShapeWays for complex parts that I was too lazy to machine/cast. You could easily draw up a design and have them make it from unpolished stainless steel. Spend some quality time with the rough parts, a surface plate, mill files, sandpaper, and some polishing compound and you could fashion some great master molds. There are also cheaper materials than metal that make excellent master molds as well. One of the more expensive pieces of equipment that I personally recommend investing in for this is a vacuum pump. You can also go the opposite direction and load the curing silicone into a pressure vessel... The only difference is that one process degasses the mold while the other crushes the gasses into oblivion. Given the option, a vacuum pull is better (not to mention the reaction will be stalled while it is under a hard vacuum if it is a moisture reactive silicone which gives you more time to remove all the gas.) This is also useful during urethane casting to prevent voids. For low volume, this is a great option and well worth your time to investigate.

Good luck, and post updates!

[Bruce Johnson]

Hugh, that's a good explanation and comparison of 3-D printing. I have some experience with it, but haven't stayed completely up to date as the technology develops. Hell, I was in engineering school in the '70's. I think that the SLS type machines will continue to develop, and within a few years, there will be thousands of small fabrication shops that will pay a couple hundred grand for a nice SLS 3-D printing machine that will sit right next to their couple hundred grand CNC machine. The two types of fabrication complement each other, and these little shops will be able to turn out nice complex shaped parts to high tolerances. But they won't be dirt cheap. The pricing will be best suited for prototypes and short production runs, similar to pricing right now for CNC machined parts. They will charge $100/hr, which will be needed to cover their overhead. The spread of the technology will be similar to what's happened with CNC waterjet cutting machines. Not too long ago, waterjet cutting was exotic technology. Now many small fab shops have them. They are still fairly expensive investments for a small pro fab shop, and it's not likely that they will come down to the home-garage shop level. That's probably what will happen with the 3-D printing machines too. It won't be worth our while to buy them for ourselves, but it will become really easy to e-mail your files to a local place and pay them by the hour and by the pound of plastic.

In regards to casting the pickup parts in silicone molds, I still haven't found the need to set up any vacuum rig, either for making the silicone molds or for casting the parts. Besides pickup bobbins, I've also been casting decorative external parts for instruments, for myself and for clients. With a little care in the stirring and pouring, I'm not having any problems with bubbles or voids. I'm getting smooth crisp parts, almost every pour. I could certainly build a vacuum rig, but I'm not seeing any reason why I should bother.

[rickmorgan2003]

In regards to casting the pickup parts in silicone molds, I still haven't found the need to set up any vacuum rig, either for making the silicone molds or for casting the parts. Besides pickup bobbins, I've also been casting decorative external parts for instruments, for myself and for clients. With a little care in the stirring and pouring, I'm not having any problems with bubbles or voids. I'm getting smooth crisp parts, almost every pour. I could certainly build a vacuum rig, but I'm not seeing any reason why I should bother.

Bruce, thanks. That's good to know, I was just looking into the whole process since you all inspired me to try it. I have a vacuum frame press I made for making laminated guitar tops so it wasn't going to be a stretch to to adapt the system but it was just one more thing in the process that was intimidating me.

[David Schwab]

What is the Definition of a more Expensive Machine?
Thousands, Tens of thousands, Hundreds of thousands???
T

Here's the machine they have:

Dimension 1200es 3D Modeling Printers| Stratasys

I looked it up and it said "The Dimension BST is an obsolete system and no longer manufactured"

I found a British website that said: "Starting at £18,900 Dimension 3D printers represent a major price breakthrough - with leading 3D printing technology." So by todays exchange rate, that's $29,031.

http://www.laserlines.co.uk/acatalog/info_20.html

He said they had made upgrades to it at some point after we used it.

[Rick Turner]

Look into "DLP" 3D printing. It's a total game changer. The resolution is incredible, the machines are relatively inexpensive, and for small parts, it may be competitive with several other technologies.

Bruce's solution of casting urethane parts in silicone rubber molds is also spot on.

[Spence]

Are these any good?

[ReWind]

[ATTACH=CONFIG]24912[/ATTACH]
Are these any good?

Only if the insides have the proper text and ejector marks - like this: