Stainless Steel Rods + Bearings?

I'm in the process of designing my first reprap, and the design I was looking at uses linear bearings (LM8UU). I'm thinking that stanless steel would be a good material, because it doesn't rust, and I was reading up on how surface harness matters when dealing with bearings. The rods I chose had a hardness of about 160 on the BHN scale, and the reprap guide says that it should have a hardness greater than 60 HRC. I'm basically wondering if anyone has stainless steel on their printer with bearings, and how it's working.

The rods: [www.grainger.com]$

Mounting rods and ensuring that they are parallel can be tricky. Look into used linear guides on ebay- you can use a single linear guide for the X axis and either a single wide one or two smaller ones for the Y axis simplifying the mechanical stuff considerably. Linear guides have almost no detectable play in the bearings and will yield very high print quality. They're easier to mount, more compact, and don't flex like end-supported rails. I would guess that a quality used linear guide with a couple bearing blocks would cost only a few $ more than a pair of 8mm rods and a set of LM8UU bearings and associated mounting hardware. They're worth every extra penny!

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I'm planning on building a Wallace. How would I incorporate a single linear guide on the design, if the 3d printed parts for it use rods with bearings? Would hardened steel rods work?

I thought you were designing something yourself. Never mind. Linear ball bushings should only be used on hardened steel guide rails. They will destroy anything softer.

The printer "design" you have chosen is a poor one and will cause you nothing but heartache. It is incapable of producing quality prints.

See [www.instructables.com] for a little education before you start buying/building.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

In that case, what should I build? As you can probably tell, I don't have a whole lot of experience in dealing with 3d printer design, so I'd like to know what I should do? My goal would be to make something for under $250. I mainly liked the Wallace because of the frame design, but if you have something in better in mind, please tell me.

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Lazerlord
In that case, what should I build? As you can probably tell, I don't have a whole lot of experience in dealing with 3d printer design, so I'd like to know what I should do? My goal would be to make something for under $250. I mainly liked the Wallace because of the frame design, but if you have something in better in mind, please tell me.

The Prusa i3 and various "reworks" are one of the popular DIY repraps
You can use a plywood laser-cut frame with M10 threaded rods.
M8 smooth and LM8UU linear bearings

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My updated Instructable on our Prusa i3 Build
[www.instructables.com]

At that price point I'd aim for a prusa i3, it at least has a frame that supports the Z smooth rods from top to bottom giving it much better stability compared to the wallace design. As for material from bad to good would be: plexiglass, wood, aluminium, steel. When sufficiently thick plexiglass and wood can be good though. Plexiglass 10mm minimum and wood I'd recommend 12mm. I used 6mm and it does flex a bit. I'm planning on replacing it with 2020 aluminium X extrusions, a bit like the folger tech 2020. With some proper bracing it can be made into a very sturdy frame while being very flexible for upgrades and changes I want to make like a bigger build space.

To get into 3D printing I would recommend to get a kit for around 450 euros/dollars. It will work properly and will save you much frustration. Digital dentists design is structurally very sound and it's a great read to get an idea what's involved, but can be hard to fit into your budget, as is my suggestion of 450 euros/dollars. I'd save up some more money and get a reasonable setup rather than scavenge build it.
If you've got more experience you'll be better at judging what is important to you and buy the parts that suits your needs. The prusa i3 design is very flexible (in my opinion at least), you can add and change it with your own designed parts or bought from ebay/alieexpress. My Wooden i3 has gone through many upgrades and improvements and learned a lot along the way.
Would I start from scratch with what I know now I'd do it much differently like using aluminium extrusions for the frame, aluminium y carriage, 24V PSU for heated bed, thermo couple and all metal hot end (E3D v6), single Z motor with timing belt, bowden setup and auto bed leveling right from the start.
I wouldn't change my first printer choice though, all the flaws has learned me a lot what's important about 3D printing. If problem solving is in your blood I'd get a cheap kit and expand from there. You can add/buy incremental upgrades to improve the design. That would be much easier than to start from scratch.

Yeah, I was considering that buying a pre-made kit (not pre-assembled) from folger-tech. It was aceylic, not very sturdy, but it works, and it has everything there to get started. Is is an i3, but I should be able to modify it later to be better. It's currently $290 shipped on ebay, and apparently the directions are bad, but it's probably better than just going off of something where I picked all the components myself. Does that sound like a good option.

You'd have to try hard to find a "frame" design that is more flexible than the design you referenced. The i3's are a little better, but only a little. Flex in the frame is one sure sign of poor printer design/construction.

Instead of thinking about your budget first, think about what you want the machine to do for you. What sort of print quality is acceptable? Do you plan to print nothing but Yoda heads and tugboats or do you want to do some semi precision work with parts that fit together? What sort of materials do you want to print with? Once you have answers to those questions start looking for designs, kits, etc. that can meet your performance goals. That will tell you how much it will cost. There's no point in spending $250 on a machine that can't do what you want.

I know you're itching to jump on the 3D printing party bus, but some more thought and research will help you avoid a $250 mistake. If you don't yet know enough about 3D printing to articulate your performance requirements, you're setting yourself up for disappointment by buying whatever machine fits your only stated goal of $250.

If you are very resourceful and willing to spend some time shopping for parts carefully, you may be able to put together a decent printer for $250, but you have a lot to learn first.

I know it sounds complicated, but 3D printing is a very complicated endeavor, especially getting the best performance from the hardware and software. If the research required to define your performance requirements is too much trouble, maybe 3D printing is, too. Most, if not all, cheap 3D printer kits will require you to become an expert on all the machine's quirks and foibles, in addition to learning at least slicing software and maybe CAD, too.

Edited 1 time(s). Last edit at 10/07/2015 03:45PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Only you can make the decision to go down a certain path. In my case I thought it really helpful to start from a kit that I knew 'sort of works', so I can wholeheartedly recommend this path from my own experience, if you keep the points of 'not a perfect printer' in mind. The skill set includes mechanics, micro controller programming, electronics, 3D modeling, IT, software. I've invested triple the amount of cost over the initial 465 euros I paid for the kit to get to a point the prints come out well first time with good enough quality. That includes tools, parts, chemicals for adhesion, electronics, plates, filament etc.It's funny how one finds resources to put towards such a project

Of course you'd want the most perfect printing performance of a $10.000 machine for $250 with as little effort as possible. On the other end of the scale you also want to learn about a wonderful emerging technology, the many possibilities that opens up to those who can master the art of 3D printing. Wherever you decide to step on the train I'm 100% convinced you'll learn a ton in many different disciplines, and possibly have a lot of fun along the way.
It's a bit like learning photography with a DSLR, a very steep learning curve, a lot of ground to cover in multiple disciplines and a lot of practice is needed but it's absolutely worth it and you'll have fun along the way.

Considering my previous experiences of using a rather tempermental Reprap (looked like an original mendel, used 3mm PLA) that was at my community's haker space, I have a bit (but not much) experience with a 3D printer that doesn't quite work. Having experience making 3D models and slicing them up as well, I feel like the only thing really limiting me is time and knowledge of physical construction (although I have done quite a lot of cicuit design). The $290 i3 kit, while made of not-so-good plexiglass, seems like a good base to build on, as it comes with every piece of hardware that is neccessary. If I were to build my own, I'd probably end up just getting frustrated, or simply overlooking something important that makes everything not work. Is all that time and frustration worth about a $50 delta for me? Would I learn a little bit less if I go with a kit? Probably, because building on something that already works (for the most part) seems like a bit more fun to me than hours of research in an unfamiliar field. While I may not learn as much, I feel like it will get me printing sooner and smoother than a home-made one.

For many many years people who had never used any other OS were under the impression that it's normal to have to reboot a computer every hour or so and to have to reinstall the OS every 6 months or so to keep a computer working. Likewise, many people have only experienced bad 3D printers so they think it's normal to have to struggle with leveling and zeroing and getting prints to stick to the bed, to have a wobbly Z axis, to have an under powered bed heater that takes forever to get up to print temperature if it does at all, 4 point "leveling" system for the print bed that bends the bed instead of leveling it, taddition of a glass plate to try to flatten it, no enclosure to allow ABS printing, two Z axis screws made of threaded rod driven by two motors that allow the X axis alignment to shift if you look at the machine wrong, flexible guide rails, flexible frame, extruder that jams, etc.

Yes, the kit has a list of desirable 3D printer features and when it's assembled it resembles a 3D printer. But it probably shares many of the same problems you were having with the unreliable machine at your hacker space. What did you learn from that experience? 3D printing doesn't have to be as unreliable as you have experienced, but you have to learn from the bad printer you already used. Don't underestimate your abilities. You fear leaving something important out that makes it all work. The kit maker has done exactly that because all they care about is producing a machine that looks like a 3D printer that they can sell for $300 or less. The thing they left out that would make everything work is quality.

A lot of people say "I'll get this cheapo kit and as I learn about its problems I'll fix the things that are wrong with it". The problem with that idea is that the cheapo kit can't be converted to a good machine by replacing parts one by one any more than a Yugo can be turned into a Ferrari by replacing parts one by one. It is so fundamentally flawed that there is almost nothing in the kit that will be reusable to build a quality machine. It will be $300 flushed down the toilet. Why not skip that step and save yourself the trouble and expense and go right to the good version of the machine? $300 will buy some high quality parts.

The mechanical stuff isn't rocket science. Take the frame design for example. There's one simple rule of thumb that will allow you to make a better frame than 99% of kits: if you push on it and you can see it move, it isn't rigid enough. That's as complicated as it gets. If you can accept this principle but don't know where to go from there, look at some quality machines and ask questions here. Don't ask "which printer should I buy?", ask "how do I build a rigid frame?".

You know more than you think you do, you just have to learn to apply it. THAT is education that is very worthwhile because it will serve you over and over again.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

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the_digital_dentist
A lot of people say "I'll get this cheapo kit and as I learn about its problems I'll fix the things that are wrong with it". The problem with that idea is that the cheapo kit can't be converted to a good machine by replacing parts one by one any more than a Yugo can be turned into a Ferrari by replacing parts one by one. It is so fundamentally flawed that there is almost nothing in the kit that will be reusable to build a quality machine. It will be $300 flushed down the toilet. Why not skip that step and save yourself the trouble and expense and go right to the good version of the machine? $300 will buy some high quality parts.

However, just as you can use a Yugo to get the parts of your Ferrari together, you can use a cheapo printer to make the parts of a good one. And, whilst a Ferrari is necessary sometimes, for a lot of the time you can get by with a Yugo.

The analogy also isn't fair in another sense... 3D printing today is like motoring in the 1900s... back then, if you owned a car, you either needed to be a mechanic, or employ a mechanic/chauffeur. There were no Ferraris back then! Or like owning a computer in the 1970s/80s.

The other problem is how to know if what you're about to buy is a high quality machine, or just a high-priced piece of junk.

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The mechanical stuff isn't rocket science. Take the frame design for example. There's one simple rule of thumb that will allow you to make a better frame than 99% of kits: if you push on it and you can see it move, it isn't rigid enough. That's as complicated as it gets. If you can accept this principle but don't know where to go from there, look at some quality machines and ask questions here. Don't ask "which printer should I buy?", ask "how do I build a rigid frame?".

Again, this is over-simplifying. All design is compromise. I could build a really rigid frame out of granite, but it would never be a good printer. The really interesting question is "How rigid, light, fast, big, functional a printer can I make for my money?"

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You know more than you think you do, you just have to learn to apply it. THAT is education that is very worthwhile because it will serve you over and over again.

This I do agree with!

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frankvdh
However, just as you can use a Yugo to get the parts of your Ferrari together, you can use a cheapo printer to make the parts of a good one. And, whilst a Ferrari is necessary sometimes, for a lot of the time you can get by with a Yugo.

The analogy also isn't fair in another sense... 3D printing today is like motoring in the 1900s... back then, if you owned a car, you either needed to be a mechanic, or employ a mechanic/chauffeur. There were no Ferraris back then! Or like owning a computer in the 1970s/80s.

The other problem is how to know if what you're about to buy is a high quality machine, or just a high-priced piece of junk.

I can't imagine how a Yugo would help you build a Ferrari, and poorly printed plastic parts will not help you build a quality printer. I know the romantic RepRap philosophy about printers printing printers, but the reality is printed plastic parts don't belong in a quality printer. A quality printer requires relatively precise alignment of certain parts. Printed plastic does not provide the necessary precision, accuracy, or strength.

You're saying there are no high quality printers from which to learn and emulate. That's dead wrong. These machines have been used in industry for at leat 20 years. There are plenty of people on these fourms who can provide info about how those machines are built if you can't find any info on the web. There are plenty of amateur built machines that print well and reliably. Unfortunately you don't see much about them here because they aren't posting questions about all the common problems because they don't have those problems. All you have to do is ask the right questions. Shift your thinking from "how do I get rid of the Z axis wobble in my cheapo printer?" to "how do I prevent Z axis wobble in the printer I want to build?"

You know if a printer you're looking at is a piece of junk by looking at how it is made- you just have make use of your experience. The OP already had experience with a poorly made printer. Plastic/plywood/mdf frame? Junk! Threaded rods instead of lead screws? Junk! 4 bed leveling screws? Junk! The majority of posts in these forums are lessons in what doesn't work. How many thousands of posts about Z axis wobble do you have to see before you realize that threaded rods don't belong in the Z axis? How many posts do you have to read about prints not sticking to the bed, underpowered bed heaters, clogging extruders, etc., does it take before you ask "how do I prevent the problems that everyone here seems to have?"

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The mechanical stuff isn't rocket science. Take the frame design for example. There's one simple rule of thumb that will allow you to make a better frame than 99% of kits: if you push on it and you can see it move, it isn't rigid enough. That's as complicated as it gets. If you can accept this principle but don't know where to go from there, look at some quality machines and ask questions here. Don't ask "which printer should I buy?", and then spend the next year or so asking how to fix all of its problems, ask "how do I build a rigid frame?".

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frankvdh
Again, this is over-simplifying. All design is compromise. I could build a really rigid frame out of granite, but it would never be a good printer. The really interesting question is "How rigid, light, fast, big, functional a printer can I make for my money?"

You could build a rigid frame out of granite and it would work beautifully, but thinking for just a moment about granite (and ignoring the cost) tells me that it would be very heavy, and I'd have a heck of a time cutting it, drilling it, and attaching things to it. I can dismiss it without much more thought than that. Selectively turning off your brain is never a good option. Doing things the right way requires thinking all the time. You recognize that granite is a problem but you're willing to accept that acrylic, plywood, or mdf are good choices simply because some kit makers puts them out there in spite of direct personal experience and the thousands of posts in this foum that tell you otherwise. Surely there's something between the two extremes that provides rigidity at a reasonable cost. I guess that's something to think about...

The answer to the question about how good a machine you can make for a specific amount of money is impossible for anyone to answer. It depends on your resourcefulness, access to tools, access to parts, how much of your brain you're willing to use, exactly what you consider a good printer, etc. If you assume you're going to purchase all new parts the answer is quite different than if you are going to scrounge parts at scrap yards, or repurpose things that are available to you from other sources. If you say "what can I build for $300 from all new parts?", look at what's available comercially for $300, and then decide if that's an acceptable level of quality (here's a hint- most of the machines people here have problems with are the $300 kit variety). Asking which $300 printer kit you should buy is like asking whether you should buy a red Yugo or a blue one. The answer is "it doesn't matter"- either way you're going to end up with a machine that you're going to spend more time adjusting, tweaking, repairing, and swearing at than you will printing.

If you get nothing else from this discussion, get this: there are no good $300 printer kits. They're all junk. You already know this. Admiting it to yourself is the first step in moving toward quality.

Edited 5 time(s). Last edit at 10/09/2015 02:29PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]