Re: 3D Printers

OK I understand now. If you recognise a good one in a pallet load and know what its worth to you then it might be worth a punt.

Closed ones tend to give more reproducible results.

There is a clear advantage in picking one that is known to be beginner friendly and easy to set up correctly for printing. Preferably using one of the file formats that your design software can output. There are some with their own bespoke formats which can be a bother.

PLA is pretty much the workhorse default.

They are worth a look. The ones in our library are often available for use when the schools aren't using them on certain days of the week. I may have a slightly distorted view of how easy they are to fix as our volunteers include people who work for a company that make high volume automated drugs testing machines and large scale X-Y samplers.

An hour to a mornings work seems typical depending on what they have done to it.

If you outsource printing I'd definitely suggest outsourcing 3D printing at least until you have enough experience of its quirks to know exactly what you want. OTOH there are some pretty good single filament budget 3D printers now under the £400 mark that are allegedly beginner friendly. I'm seriously tempted but would have to clear some bench space.

I have my own A4 & A3 inkjets (and a near photoreal colour laser). The latter is good enough to pass for offset printing with the right paper. Inkjets need a certain amount of regular use or the ink dries in the printhead clogging them which can be tedious to sort out.

A friend has a photo cure laser resin one and that is messy in terms of wet chemistry but good for prototyping fine parts and easier to set up.

If the XYZ space frame is bent more than a tiny amount out of true it can be difficult to put right or compensate for.

It all depends how often you need to do it and how you value your time. I have a couple of friends with 3D printers who enjoy it and I tend to ask them to print things for me in return for the rest of the roll.

My all time favourite 3D printed object is a digital sundial...

If you get one for very cheap then there is potential value in getting them working, but modern printers are much more of an appliance that 'just work' rather than older ones which require more fiddling.

Modern printers are also cheap too - I have an Elegoo Centauri Carbon which is $300 and has a lot of capability that was difficult on previous printers, so if your time is valuable it is better to get something like that rather than spend $20 on a junk printer and $200 of time/parts trying to fix it up. If it's a hobby then fine, but if you just want to print things then the $300 machine is a lot less hassle.

That $300 entry point is also not a very high bar compared with using third party services. If you are going to be printing very much, you'll pay more contracting out your jobs, and the turnaround when printing them yourself is a lot quicker.

If you want to do something that isn't supported by a commercial device (eg

Theo

Maybe 3D printers are cute toys that people get tired of using.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

In which case new will mean you are debugging your designs, while with an old machine you're also debugging the printer.

A correctly set up printer will 'work', but a) the setup can be a pain, b) the older it is the more fiddling needed to keep it in tune, c) it may not print as well / do materials the new one can.

Depends on the tolerances, materials etc. If you are expecting a very tight fit you won't get it. If a gap is acceptable then you can do that. But most materials aren't designed for low friction.

I agree you need to pick the right tool for the job.

One useful feature is dimensional stability and repeatability - if I want something exactly 47mm in length then I can print that repeatably, but if I tried to hand cut that the tolerance would be much worse.

- custom fittings that I need right now, eg I need a 23mm cable grommet to put around a pre existing cable

- templates, eg I needed to route a 66mm hole in wood, so I printed a template

- mockups, eg I wanted to see if a certain sort of valve would fit in a space, so I drew a model in CAD and printed it

- enclosures, where you need to protect some circuit

- brackets and fixings

- random 3rd party designs, eg recently a server drive cage, a vacuum nozzle, a hose adapter, a chisel sharpener, an adapter for a circular saw to saw track, ...

A couple of themes stand out: being able to have something today, not wait for delivery, and being able to print something for pennies versus pay over the odds for a shaped piece of plastic plus delivery fees.

The other thing is it front loads the time element. Yes it takes time to design the thing over making it by hand, but once you have the design then printing copies requires little effort, while hand making the thing scales linearly with the number required.

Theo

Are these US government property auctions by any chance? It occurs to me that this could be due to a quirk of US science funding, that if you buy a piece of equipment the government owns it and you have to hand it back at the end of the grant. It goes to some disposal contractor who sells it for pennies on the dollar.

In that case the gear may be relatively new and in functional condition, as against a regular auction where equipment might only be disposed of when it's life expired.

You can research models to see when they were released to confirm.

Theo

Examples of real use: - parts of a cart for my brother. He has a fully equipped wood shop. - fill ring for a tiny drill, to fit a press for a larger drill - My lathe has a divider, but there was only one divider disk. I made the other two that belongs to them, these disk have some hundred holes. It is nerve wrecking to drill these holes.

(I have printer organ pipes, but that is not yet fully practical, though they sound and can be printed for any pitch.)

More often than not,a first attempt fails.or is not perfect. For little effort you can improve your design.

The technology is the same, but the quality of life has improved. For example, modern printers have automatic bed levelling, nozzle cleaning and profile shaping (measuring their own kinematics with accelerometers). Older ones didn't, so those had to be done manually. Additionally modern designs print quicker and have different design choices which improve performance (eg direct drive rather than Bowden tube - where the filament feeder is on the head not fixed on the chassis), and enclosed units allow printing higher temperature materials like ABS, nylon or PETG.

Additionally being able to control things from a web page or app, rather than walking up to the unit with your print files on an SD card, and being able to monitor the job remotely with an integral camera are nice quality of life improvements missing in older printers.

Setup meaning calibration and adjustment. If they aren't set up correclty you can get printing artefacts (stringing, rough prints) or print failures (lack of adhesion means the print fails to stick and the printer prints a ball of 'spaghetti' in mid air). More modern printers do more of this setup automatically - eg bed levelling used to be done with manual thumbscrews and a sheet of paper as a feeler gauge, now it's done by measuring the height of the bed at different spots and correcting in software.

Filament also needs to be kept dry, so there's an ecosystem of filament dryers and dry boxes. I use these as a cheap dry box:

I've not tried this kind of thing, but there are designs like that out there and often work remarkably well. But if you are expecting tolerances like in an engine (ie gas tight to 0.000...1") you won't get them from a consumer printer.

To be honest, if this is for business purposes I'd just spend the $300 and get something that works out of the box. If you want to tinker to understand how things work, by all means additionally buy a used machine and play with it but don't put tinkering with your machine on the critical path. If you need some part *today*, you don't want that to be roadblocked because you had to take the machine apart to fix $problem.

Most of the cheaper machines are limited by build volume (eg 256x256x256mm), so a two-machine solution could be to get a machine with a bigger volume as your second. Most of your prints will fit on the smaller machine, but the bigger one is there when you need that feature. A bit like most people print A4/Letter but sometimes an A3/A2/A0 printer is needed.

Theo

Hmm, the one at the rear left looks like a Flashforge but I can't pattern-match it. Looks similar to the Creator 3:

The one at the rear right is an Ultimaker, I think it's an Ultimaker 2 series:

We had an UM2 since about 2015, it was a workhorse. But my $300 Centauri Carbon is more capable.

Not sure about the two at the front. The front right with the blue front door looks a bit like an Anycubic 4Max but it's not quite right.

Theo

"Disposed" sound silly. Where I live rule is that after grant ends any durables became normal property of the umbrella organization (typically university). When not needed equipment will be disposed, but typically it will be used as long as it is useful, which may be many years.

Relatively modern equipment comes from termination of leases, where leasing company provides support. Here support cost of older equipement and finasial rule provide incentive to dispose. But that affects normal computers and printers,

The last one is an Ultimaker 2. Not sure what the box on the left of that is, but it looks old.

Temperature is easy - most of the adjustment is mechanical (bed levelling, removing backlash from adjustment screws, tweaking feed rollers, adjusting hotend nozzle are all things I did on my old printer).

In that case, the stepper motors are programmed to follow the bed so that the part is printed at an angle that matches the bed. The part remains flat but the bed doesn't have to be 100% level.

I think some have 4-corner motorised bed adjustment.

You just need the filament to be dry, the printer itself doesn't need to be. That means either store it in a dry box (eg a plastic box with moisture absorbing silica gel to maintain a low humidity inside the box) which lets you feed it out into the printer, or in a automatic material changer that includes its own dryer. You could also just keep it in a dry box and manually remove the spool every time you wanted to print. If it absorbs too much moisture you can dry it again. The section of filament that runs from the dry box to the printer will be exposed to moisture between prints but that will be consumed early in your print so it's not a problem.

Melting some kinds of plastic like ABS can emit nasty fumes, which is a reason to keep the printer in a well ventilated space.

There's usually enough flex that you can get an interference fit if you want that. If you want slightly less than an interference fit then it might need tweaking based on the tolerances of your particular printer - I haven't explored this area, but there are certainly designs where two moving parts are printed as part of the same object, like pieces with integral hinge joints.

Yes. The modern ones mostly 'just work', the older ones need more tweaking. You are proposing buying an old one, which means that fiddling is up to you.

I think you're overthinking this. Can you afford $300? If yes, buy a new printer and learn about 3D *printing*. If you make prototypes then there is a strong justification to have parts in a few hours, not a few days.

If no, spend $150 at your auction but be prepared to repair it. You'll learn more about 3D printing and also 3D *printers* (like buying a broken car will teach you about mechanics as well as driving). It will likely cost more than $300 in your time and parts.

A smaller print head and motion has a lower mass and lower momentum so it can print quicker. A larger printer has more mass and more inertia it has to overcome. But other than that and space requirements there's no major downsides for having a larger machine.

Theo

More specialised toys that are very useful in some very specific situations, which don't come up all that often.

When we needed hemispherical fine mesh grids to voltage-select low energy secondary electrons by voltage, a 3D printer would have been very handy. The mechanical engineers just bashed some gauze into shape, which wasn't all that elegant, nor all that well-controlled.

We have a great machinist contractor who has a Tormax n/c mill and a serious 3D printer. The 3D is rarely used, mostly for test fixtures. Machining is usually better. A milling cutter can remove stuff a lot faster than a 3D printer can deposit it.

If a home hobbyist buys a 3D printer, I wonder how many things he will actually use it for.

How many princess warrior figurines does the average person need?

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

I recognised the Ultimaker 2 because we had one. I spotted a few clues on the others and did some research based on my hunches.

I suspect a lot of this stuff is quite niche. I see 'surplus' companies offering items of test equipment/etc at high prices on ebay - perhaps this is where they source them. They can't sell very quickly. Especially given buying a used piece of equipment with no guarantees that it works, no software or licences, and no support from the manufacturer is a high risk affair. Many businesses aren't going to want to play that game. There is probably a market there if you're able to refurbish them and provide support though.

Theo

or the fact that 3D printers have come a very long way since the beginning so no one wants the old finicky ones

absolutely, but a mill requires someone who understands tools, toolpaths, feeds, speeds, fixturing, order of operations, etc. and the time to program

a modern 3D printer is basically click print and wait

Wouldn't one need to learn some 3D design software? If all you want to make is some ordinary thing like a pencil holder or a coffee filter, just order it from Amazon.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Some non-curio things I've 3D printed:

• Many brackets and custom mounts for my electric motorcycle conversion, including reproduction light mounts.
• Repair parts for ABS body fairings (model, print, glue in place, paint)
• Gears and pulleys for my 1922 Southbend Lathe and Avid CNC custom build
• Custom oil filler cap for a friend's dodge challenger
• dashboard fill plate for a different friend's 1972 Nova conversion
• Repair parts for my old fridge
• Rain guard for the house's stink pipe
• Countless washers, spacers, funnels, shims, cable mounts, etc.
• Countless shelf brackets, tool hangers, wall mounts...
• Many custom project boxes for electronics projects

I don't have one. Why would you think that I should?

If I got involved with stuff that would need one, it would probably be with people who had access to a 3D printer, but that's pretty unlikely.