Who is the 3-D printer guy here?

Bill DeShivs

Bill DeShivs

Knifemaker / Craftsman / Service Provider
Joined
Jun 6, 2000
Messages
12,554
Many (most) of the American-made pocket automatics of the pre-1958 era were made with celluloid handles. These handles deteriorate-releasing nitric acid fumes that will literally eat a knife.
When this deterioration starts the best thing to do is just break the handles off of the knife to save it.

I have hand made these handles many times, but they are a pain in the rear to do correctly. I have messed around with casting them from acrylic with some success but the process is not perfected.
The handles have holes for the button and safety that must be placed exactly. In addition, there is a cutout under these holes for the mechanism..

Being the dinosaur that I am, I only recently thought about 3D printing. Some of the parts that I have seen had visible layers, but I'm sure that is avoidable. If not-and the proper material is used, sanding and polishing the outside is not a problem.

Should someone like to confer with me, I believe I could make you quite a bit of money. I don't want or need to get into the printing business. I already have a laser engraver that I have no idea how to use, and little time to learn! I have the knowledge of how these parts should be made, the characteristics of the material that needs to be used, examples to use as patterns, marketing expertise, connections and the name to sell them.

Anyone intersted?
 
I have a couple engineering buddies who have their own personal printers. I'll ask them this week if they would be interested...?
 
I have a small 3D printer I use for prototyping work. They are very handy.

As for finishing, many of the big names in the metal finishing business (think tumblers, bead blasting, high efficiency finishers etc) are coming out with all kinds of products and machines specifically made for finishing and smoothing out 3D printed parts.
 
Getting a filament that's suitable for scales that will print in a normal 3D printer might be difficult. Using 100% fill it should provide a pretty solid fill. I'm expecting it will require a very expensive 3D printer to do the work.
 
Hi Bill DeShivs Bill DeShivs ,

I have a bambu labs printer and have fooled around with some scales. A few things to note:

1. FDM printers (fused deposition modeling) are what most people mean when they say "3d printing" so my comments will be in line with that method. Not resin printing. Using FDM, you are essentially transforming thermoplastics while they are in their liquid state through controlled pressure extrusion. Notice, I said thermoplastic...not thermoset plastic. All of these types of products have a relatively low temperature point at which they revert back to liquid state. You can abate this with some higher (aka. more expensive) filaments, but regular PLA will get soft in a hot car. The filament type options begin to become restricted, as design intent grows (don't melt + no lines + sandable or smooth finish+....)

2. Printing takes a while....maybe 4 hours or more for a set of knife scales? The printer really hauls the mail, but it's a lot of pathing to perform.

3. Shrinkage: another heat related issue that really needs to be dialed in on any mechanically fit oriented components.

4. Humidity control: desicant is your friend and drying all of your filament to the driest level possible is always important. Small droplets of water that get extruded on/in the filament explode at micro levels in the process and leave you with bubbles.

All that being said, you can get a nice setup like mine under $1k so likely cheaper than the laser ;)

Reach out if I can do something for you, partner.

John
 
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ABS can be vapor smoothed with acetone fumes. In very short order the layer lines will disappear and leave a uniform glossy surface finish.
 
Prints require post processing. It can be time consuming. I recommend a MiniMill.
 
Better than a mini mill is to find someone who does CNC milling. They can crank out exact size scales in most any material. I have a friend who makes micarta and wood scales for his knives that are ready to mount, including drilled and countersunk holes. A few licks with fine sandpaper after mounting and they are done.
 
Stacy E. Apelt - Bladesmith said:
Better than a mini mill is to find someone who does CNC milling. They can crank out exact size scales in most any material. I have a friend who makes micarta and wood scales for his knives that are ready to mount, including drilled and countersunk holes. A few licks with fine sandpaper after mounting and they are done.
Click to expand...
If the quantities are very high at all it will likely be cheaper and a lot better quality to have them made on a CNC mill. Production quality 3D printers are quite expensive and even though they have come a long ways, the quality of CNC milling is just going to be a lot better. You will need sufficient quantities though to get the cost of development on a CNC mill spread out. Depending of coarse upon how much value a single handle has.
 
Bill DeShivs said:
Many (most) of the American-made pocket automatics of the pre-1958 era were made with celluloid handles. These handles deteriorate-releasing nitric acid fumes that will literally eat a knife.
When this deterioration starts the best thing to do is just break the handles off of the knife to save it.

I have hand made these handles many times, but they are a pain in the rear to do correctly. I have messed around with casting them from acrylic with some success but the process is not perfected.
The handles have holes for the button and safety that must be placed exactly. In addition, there is a cutout under these holes for the mechanism..

Being the dinosaur that I am, I only recently thought about 3D printing. Some of the parts that I have seen had visible layers, but I'm sure that is avoidable. If not-and the proper material is used, sanding and polishing the outside is not a problem.

Should someone like to confer with me, I believe I could make you quite a bit of money. I don't want or need to get into the printing business. I already have a laser engraver that I have no idea how to use, and little time to learn! I have the knowledge of how these parts should be made, the characteristics of the material that needs to be used, examples to use as patterns, marketing expertise, connections and the name to sell them.

Anyone intersted?
Click to expand...
Bill
one of my brothers kids has a 3d printer...he has made a few things on it...the Durability might not be what you want
i think having plain old micarta done in cnc would be much better....they make/sell cnc wood routers that are table top size
it should be able to handle micarta scales pretty easily...... i don't have one or know how to program it... but if you have the files made you could easily turn out parts in short time
just a thought outside the box here....
 
Some of you may not understand about this project.

These knives are small pocket knives, 2-7/8" to 3-3/4" closed. They are (usually) double blade autos.
While Micarta is a wonderful material, it wasn't used on these knives. What we need to make is accurate restoration parts.

Here is a picture. You can see the inside of the handle on the right.
Click on picture to see full view.
 

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They could be CNC machined or 3D printed from acrylic (or whatever they need to be made from to be correct) but they would have to be polished afterwards to get that very smooth outer finish that they have. Those must've been molded originally.

I believe to successfully 3D print those out of acrylic you would need a rather high end printer with a dual filament head.
 
Copy with silicone molds and pour in whatever is liked.
 
JoeBusic said:
Copy with silicone molds and pour in whatever is liked.
Click to expand...
I have seen folks use a 3D printed PLA model as the core for various molds that will be used for metal pouring. They burn out easily and can leave a nice definition mold if done well.
 
Cnc is a good idea if the scales are standard sizes. If there are a bunch of different sizes and shapes with lots of one-offs, 3d printing may be better, but it would need to cost enough to pay for the CAD work necessary, as well as the trial and error to get a perfect fit. Durability is not an issue for that application if a suitable material is used. PLA will not hold up and should be avoided. ABS and HIPS can be chemically smoothed for a smooth glossy finish. Plenty of other materials can be chosen if hand polishing.
 
Polishing is not a problem. If I make them by hand I have to polish them. I am trying to avoid as many hand operations as possible, but I know some will be unavoidable.
 
There are a lot of 3d printable materials that offer good durability. Materials like ABS and nylon can be 3d printed, and there are filaments with carbon fiber added for extra strength where claims are they are good enough for automotive use. I'm going to assume I can't give link even though BF doesn't have any competing paid dealers for filament, but if you google like "ppa-cf" as an example, a store should come up (that makes 3d printers as well and was already mentioned here) with usage examples and technical data sheets with the properties. I would think the limitation would be more on whether the color is what you're after than if there is a filament with the mechanical properties required for that job.

Edit: Depending on the material, generally yeah you'll do some work after if you want it perfect, like sanding, chemical application (like chloroform makes PLA shiny and removes any layer lines), patching with bondo. Again though that will depend on the material chosen.
 
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I came across another option that may be even better for this purpose than the other options mentioned. You can get a small desktop vacuum former for under $1k. You can make perfect molds to be able to cast resin, silicone, etc. Would cut down on finishing needs, and no CAD work required.
 
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