3D Printing - Big Struggle Featured

Don't have a 3D Printer... only know about what I've read🤷️

Hackaday has several pointers for this, mostly by using inserts:

Don't have a 3D Printer... only know about what I've read🤷️ Hackaday has several pointers for this, mostly by using inserts:

----------------------------------- Thanks, I didn't know about that type of insert.

At Segway 'someone' inadvertently screwed a valuable injection molded prototype part together with permanent Loctite and I was tasked to salvage it. Such tasks are thankless to protect the guilty, typically a department head with little hands-on experience.

Molten solder on the screw heads softened the plastic around the brass inserts enough to ease out and unscrew them and epoxy in the hole secured them back in well enough that I heard nothing more.

I made a number of repairs with epoxy covered with clear tape or plastic film to make it hand moldable as it stiffened. Often in an electronics lab one has to make repairs with office supplies, like Wite-Out as solder mask and file folders to model sheet metal.

Generally they seem to be melted in. I've seen a hot iron tool used with the insert stuck on the end. I always wondered if the plastic flowed in enough to really bond them. A hot screw in insert, in my mind, might hold better.

I have used to other 3D CAD systems with some success. Fusion and ViaCAD. I found the strictly parametric modeling of Fusion slow and restrictive. Use that as a basis for evaluating if ther eis any vlaue in my opinion of FreeCAD.

From what I have "seen" it is very powerful, but I have failed to complete any work with it.* It has a steep learning curve couple with different standards and interface look/feel in different modules. I guess there are some "skins" that can reduce some of that or be selected so atleast part of it has a similar feel to some other CAD program you may already be familiar with. I never got to the point of seeing that. The steep learning curve is partly because there is a lot power there, partly because it was created by coders who may or may not have had design backgrounds, and partly because it is open source with lots of add-ons written be different people who wrote their own part to suit themselves.

FreeCAD may very well be the most cpable free CAD there is, but as has mentioned the learning curve is steep. It may very well be more capable than many commercial CAD programs.

I have a FreeCAD icon on my desktop, but I can't recall the last time I opened the program.

I have used to other 3D CAD systems with some success. Fusion and ViaCAD. I found the strictly parametric modeling of Fusion slow and restrictive.

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Preferably bentonite clay, and what you describe is called green sand. In the hobby realm atleast, it seems many small foundries are transitioning to petrobond where managing moisture content when not engaged in the hobby for some time is not an issue. Petrobond uses oil instead of water for the same/similar affect. To make it clump when rammed. I think Windy Hill Foundry (cast iron foundry business) also uses petropond as their default casting sand.

Sodium silicate. Its used in solution in place of just plain water. CO2 causes it to harden allowing for few or no inclusions, and more detailed molds made from more complex patterns. The CO2 in air is enough, but venting can help for faster mold prep, and for even faster casting C02 is sometimes flushed through the mold from a gas bottle. I first ran across it when I was researching how to recycle 6061 which is not a good casting alloy unmodified. That was when I first discovered the guys building the SV Seeker marine research vessel. They were casting custom porthole covers in sand molds using sodium silicate to make more rigid sand molds.

FYI: The addition of more silicon metal can improve the cast-ability of

On 12/1/2025 12:58 PM, Bob La Londe wrote:

I've recently run into two things that may expand the scope of 3D printing in my mind. No real epiphany here, but maybe an expansion of scope.

One I already knew and mentioned. Undercuts. You can 3D print stuff with undercuts impractical or evne impossible to make by sutractive machining without complex setups, and changing relatively simple single structures into complex multiple part assembled structures. I'm talking about things beyond a non-uniform parting line. I had a customer recently send me a nice 3D .stp STEP file. One of the few that didn't translate broke or with artifacts. They had 3D printed a mold from it. There are many things wrong with plastic for mold making, but was injecting a soft cure media, and the undercuts did not prevent the part from being demolded. A machined aluminum mold would be superior for this media for many many reasons, but cutting it would be a lot of work requiring very very small cutters. I don't think I could tilt the plate enough to use those tiny cutters with their very short stick out enough to cut the features with crashing the tool holder into the part. I suggested some alternatives, but I have not heard back from them. That last part is no surprise. When I tell people the truth about what they want they often ghost me. I prefer that to those who imply I am a liar or competent, and they will just get somebody who knows what they are doing. In their case I don't think I would make their part by subtractive machining even on an articulating head 5+ axis machine. Maybe...

Parts where the raw material cost is. You need a bronze bushing. Bronze is expensive. You can usually buy a bronze bushing cheaper than the raw stock to machine one. If you are setup for it, and have been saving scrap you might be able to cast a bronze blank and then finish to spec, but generally the raw material is expensive. If a usable bushing is already available its probably cheaper. How about 3D printed bronze? You might make the argument that, "Sure, that's great if you can stock

Well, I have a dozen(+) blanks to cut from wrought stock and a bunch of molds to cut. Another Sunday spent in the shop trying to catch up. Hopefully nobody falls, dies, or has a personal emergency today dragging me out of the shop yet again.

Parts where the raw material cost is. You need a bronze bushing. Bronze is expensive. You can usually buy a bronze bushing cheaper than the raw stock to machine one. If you are setup for it, and have been saving scrap you might be able to cast a bronze blank and then finish to spec, but generally the raw material is expensive. If a usable bushing is already available its probably cheaper. How about 3D printed bronze? You might make the argument that, "Sure, that's great if you can stock

------------------------ Interesting but not yet useful for me.

So far 3D printing seems to me similar to the scenery and prop making of theatre, it can form artistic shapes mostly without function. I take it as incompletely substituting for expensive machine tools or the skill of a sculptor instead of replacing them.

I've been practicing hammering sheet metal into compound curves instead of pursuing 3D, to make things I need but can't buy. For example a replacement floor panel for my truck unnecessarily copies the no longer needed factory dip priming drain hole of the original, my patch continues a stiffening rib across that area instead.

This rule would be a severe restriction for me. I've cut pulley grooves for vee belts, steel cable and serpentine belts, all of which violate it.

There are some commercial 3D machines out building structure parts. Read this awhile back, took me awhile to find it again...

There are some commercial 3D machines out building structure parts. Read this awhile back, took me awhile to find it again...

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Thanks, that is very interesting. I don't have the mechanical engineering education to design beyond stock shapes of known properties. I just built what the Ph.Ds designed.

I've been considering hobby level 3D printing versus manual machining, not high end industrial equipment for which there was little to no need in testing or communications electronics. The machining I did at Segway was mainly to accommodate added electronics.

The parts being made were really interesting in shape. They look like something animal and plants would grow for structure rather than cast or machined.

I realize these 3D "printers" are out of reach for us peons to have about just now. I suspect the techniques and material will come down in price eventually.

There are some 3D Color printers now in our price range...

I find most things machine faster out of better materials, but for "additive" manufacturing I would like to be able to turn my scrap into some form of usable raw stock again. Foundry work.

I found a use case for some supplemental black smithing. You can argue that blacksmithing is both additive and subtractive manufacturing. I made a set of wrenches a while back using normal 2.5D machining specific to some collet chuck tool holders I use everyday. I managed to partially mangle one end of one of the wrenches. Its 4140HT, and I figured it would be strong enough before it deformed. It would have been, but I let it slip. I had cut deep enough for a second wrench, so I just sliced a wrench off the stock. However, the old wrench could have been fixed a little faster by taking a step back in time. I set it out back on the bench near where I use the forge, and the next time I fireup the forge I'll deform it a little further, and just machine out the working surfaces that hold the tool holder. Then I can heat treat it like I should have the first time around. While I did already have a

So far none of these thoughts have given me an epiphany about 3D printing, but thinking about them has started to change how I think about other processes.

Look at this cool looking thing I made. Yep. for the most part I agree, but there are companies selling 3D printed plastic parts.

There is one place 3D might be useful. To make one off hammer form or foam press form tools. I am sure you are familiar with the process of pressing a mold (die?) into heavy rubber foam to form sheet metal.

There are other forms of 3D printing where it might not be an issue. Filamant and resin to my meager knowledge level might not be suitable, but laser sintered metal powder might just do the trick. A truly capable machine would no doubt be beyond the budget of most of us here in this group, well except for our rich mining magnate from the UK (GRIN), but it can probably do that kind of work.

I'd have to ask my son about resin printing. I can think of some strategies where it might work.

There are some 3D Color printers now in our price range...

-------------------------------------------- The inspiration for 3D printing was a molten plastic ink color printer that could pile up ink as Braille or offset printing plates.

Many of the engineers had been at Centronics. I was their lab tech.

How does coloring the dots help with braille? ;^)

There is one place 3D might be useful. To make one off hammer form or foam press form tools. I am sure you are familiar with the process of pressing a mold (die?) into heavy rubber foam to form sheet metal.

-- Bob La Londe

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Actually my process is medieval, hammer stretching the metal freehand into a deeper depression in end grain oak or flaring a hole into a trumpet horn shape on the anvil horn and edges. Once stretched spherical it can be reshaped oval or whatever, the hardest were a watertight rust patch for where an inner fender well transitions into the conical strut tower and a closely fitted costume armor helmet from a salad bowl that was cylindrical above and conical below.

A punch and die aren't necessary though I have a jewelry-sized dapping punch and block set and have made a hollow silver ball necklace ornament with one. I'd like to find or make a blacksmith swage block.