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  1. #21
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    Hi Paligos, Those parts do look nice and I could have used you months ago when my Replicator 2 would not make parts that were good enough. Even though, the Replicator 2 does a good job considering what it cost and that it uses PLA. If I need some items in the future, do you accept Paypal?

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    Quote Originally Posted by tjb1 View Post
    Most engineers have a working knowledge of machining and the processes used and use those when designing parts so that YOU CAN machine it.

    Most engineers SHOULD have a working knowledge of machining and the processes used, but from what I have experienced, they are lacking much of these things.

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    Besides, this 3D printing thing is HERESY!!!

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    Quote Originally Posted by Stuart Caruk View Post
    old timers can laugh all they want. I had a request from a customer to make a custom prototype wet end for a pump that we manufacture. It had to demonstrate the fit and purpose as a model, and would be nice if it worked. I quoted 6 - 8 weeks and $6400 to mill it from 6061, or 3 days to print it from plastic for $1280.00. He took the plastic prototype. For the purpose, it worked just fine. After a few modifications it will likely be modified 2 or 3 times and then made as a stock item in larger quantities.

    There is a real place for our Stratasys Printer. It took a day and a half to print, and 7 or 8 hours in the tank to dissolve the support structure away. It took perhaps a couple hours to generate the model and be ready to print. Didn't affect our normal product one bit.

    You can print a lot more than toys if you have reasonable tools and a decent skill set.

    Stu
    Holy Crap, roll me over and paint me pink, as this is possibly the first intelligent post I've seen in quite a number I've read here on 3D printing and how it can be useful for a business to make money and create more work for their business and machines!

    Well said (and done) that man!!!

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    Since the OP started this post I have started looking at photopolymer machines. Stratasys offers a series of them. They are not cheap but the surface quality and ability to deposit fine detail is an order of magnitude beyond melting weedwacker string, otherwise known as FDM. I think that was what the OP was showing us (yes, it includes the fucking ubiquitous Crescent wrench but the surface is pretty good).

    I had a small intricate logo printed on a pattern last week and the sand-cast end product looks like it could be a die casting. It was impressive enough that we may just have to buy one. I have two observations (just as a customer so far, not a machine owner):

    (1) Photopolymer (or inkjet as people are calling it) looks like it may be the future of 3D printing, assuming a broad enough range of UV-curable materials will become available. For one thing, since it traverses the entire "page," it can print a whole row of parts in little more than the time it takes to do one.

    (2) That league of ripoff artists known as the 3D printing service industry is DOOMED, like the old neighborhood print shop and like its successor, the "service bureau" that took your Windows/Adobe output and redid it in Mac/Quark for an absurd fee just to send it to the offset platemaker. Today if you want your customers to have printed matter you put the art on your website so thay can print it themselves.

    (3) It's one more way to vertically integrate. Pretty soon every shop will have to have 3D printing capability just like today you have to be able to read (and post) CAD files.

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    Quote Originally Posted by Oldwrench View Post
    Since the OP started this post I have started looking at photopolymer machines. Stratasys offers a series of them. They are not cheap but the surface quality and ability to deposit fine detail is an order of magnitude beyond melting weedwacker string, otherwise known as FDM. I think that was what the OP was showing us (yes, it includes the fucking ubiquitous Crescent wrench but the surface is pretty good).

    I had a small intricate logo printed on a pattern last week and the sand-cast end product looks like it could be a die casting. It was impressive enough that we may just have to buy one. I have two observations (just as a customer so far, not a machine owner):

    (1) Photopolymer (or inkjet as people are calling it) looks like it may be the future of 3D printing, assuming a broad enough range of UV-curable materials will become available. For one thing, since it traverses the entire "page," it can print a whole row of parts in little more than the time it takes to do one.

    (2) That league of ripoff artists known as the 3D printing service industry is DOOMED, like the old neighborhood print shop and like its successor, the "service bureau" that took your Windows/Adobe output and redid it in Mac/Quark for an absurd fee just to send it to the offset platemaker. Today if you want your customers to have printed matter you put the art on your website so thay can print it themselves.

    (3) It's one more way to vertically integrate. Pretty soon every shop will have to have 3D printing capability just like today you have to be able to read (and post) CAD files.
    UV cure photopolymer printing is quite different to "jet" or "nozzle" printing, it's more like laser printing, technically speaking it's laser-plotting, and a direct relative of photographic plotting, or "C-print", rather than an electrostatic process involving dust as in a photocopier (which I have not yet seen an example of being used for 3D). In theory the resolution limit for that could be made extremely fine, certainly down to photographic plotting which is around 5000dpi on a laser imagesetter.

    Of the nozzle types there's the "plotter" single-nozzle thermoplastic type, or FDM, and then there's the inkjet printer head type as in zcorp, which use a water + plaster method, which can produce decent quality moulds, and in theory should be able to deliver round about 5000dpi at some point soon. It's not that zcorp is similar to an inkjet printer, it is an inkjet printer.

    Some of the best idea with UV cure technology is to use some sort of very high resolution DLP raster projection system rather than a single-point laser, but the laser method while slower yields more precise results, and baking a 4k DLP chip with high-powered UV light probably isn't good for the longevity of the chip. Maybe there's special coatings for the mirrors, but UV light really will destroy stuff. The interesting feature is that a conventional projector bulb is metal halide, and those require very powerful UV filters, so presumably one could simply build a video-projector bulb without the filters and one has a very dangerous bulb which would definitely cook plastic and give a person sunburn to second degree burns and burn holes in your retina. The problem with high-speed plastics production systems is the resolution of the DLP chips is limited, so for larger parts one can imagine that a 1024x768 chip over a 6 inch part won't really make small pixels unless one actuates the DLP head.

    Scanning a DLP head in one dimension with a very small lens equivalent to the use of an inkjet printer, with 1024x768 projected over 1/2", that would produce 0.0005" precision or 2000ish dpi. The build-head would incorporate a high powered UV metal halide bulb, and actuating the build table and bed in one dimension and the build head in one dimension, that could produce a medium-speed ultra-high-resolution plastics printer. In theory that could be scaled to an arbitrary size, or incorporate an arbitrary number of print-heads.

    The other notably missing feature of additive plastics forming processes is the lathe option, where you start with a cylindrical or rough-machined lathe plastic part, and scan with one axis of rotation and actuate the print head in one linear axis adding plastic. Presumably to do raster printing one would need some sort of cylindrical lens with cylindrical focus, it could get quite difficult, but a high-precision point-laser plastics lathe could be useful. Cube-shaped voxels or similar don't work for cylindrical features.

    The obvious utility of the plastics-based processes is the ability to produce masters for castings and moulds for metal, which can be employed for forging or casting of proper metal parts rather than the variable and rather chalky strength of direct-metal parts, which are in practise rather prone to breaking and have to be over-engineered, main reason those get used is where you absolutely have to have extreme lightness and a structure made mostly from air, and that means titanium.

    Titanium is a bit of a nightmare to work with, because it's basically halfway to high explosives. Melting a very small quantity of Ti in a protective gas shield or ideally a very strong vacuum as on the better direct-metal systems, and one gets a completely new process which can only do certain parts of an assembly. This is great for some sorts of things, but horrible for others. Cogs are not a great idea. You really don't want a direct-metal roller bearing. Might at a push be able to do the bearing cage with direct metal, but none of the load-bearing surfaces of a bearing will be any good at all compared to a properly formed equivalent. This is not a problem in practise, because you just provide bearing seats for mass produced bearings on a direct-metal part, and the bearing seats can be machined to greater precision than the typically 300dpi ± more than you'd like with most direct-metal processes.

    On the other hand, similar light and good quality parts of a completely different profile could be produced in numbers from magnesium by either hot or cold forging in a press or casting from various high-precision plastic masters.

    Obviously any formed metal parts can be subsequently machined, typically facing and threading is sufficient.


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