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  1. #1

    Advice on HiRes printer choices

    I'm approaching the purchase of a 3D printer from the opposite direction to many of you: I have a specific mechanical device I want to make, that consists of <20 mechanical parts that must work together, for instance with two parts sliding together on a dovetail. For this I need good mechanical accuracy, so a high res printer seems to be essential. I need to make parts that will be no bigger than 4x2x1 inches, and I need a moderately strong product. If I can get the product working in plastic, the intention is to replicate this in steel, but I want to be sure of mechanical function first. If my budget is ~ 1000 (euros/pounds) what is the best machine to buy?
    Last edited by JimB; 03-04-2021 at 03:51 AM.

  2. #2
    Super Moderator curious aardvark's Avatar
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    how strong do the parts need to be - ie: what kind of stress does the most stressed part take and in what directions.

    Fdm printers can make very strong, durable and practical parts (99% of all my prints are practical).
    But for some things a resin printer using a 'tough' resin might be more suitable.

    Oh and start thinking and working in millimetres. Pretty much all the 3d printing specific software only works in mm.

    If you look on thingiverse there are fully 'working' 3d printed car engines. So the fitting things together is not going to be the issue.

    Choosing the right material to make the parts from is probably more important.

    Also how you design the parts makes a HUGE difference.

    Parts designed specifically to be 3d printed will be stonger and mush easier to print than parts you just designed without taking 3d printing requirements into account.

    Probably the best suited to your purposes at the moment would be a flashforge replicator pro 2 - ungortunately It's pretty new and i can't find a uk distributor.

    How 'handy' are you with mechanical things ? ie: would you be happy with a build it yourself kit ? as opposed to a ready built machine ?

  3. #3

    Some answers

    Quote Originally Posted by curious aardvark View Post
    how strong do the parts need to be - ie: what kind of stress does the most stressed part take and in what directions.
    There should be minimal loading, the intention is to confirm "unloaded function", that is to say, do the bits work together correctly? This is intended to be a Proof of Concept before going to the much more expensive steel fabrication, and so the device function can be quickly and simply demonstrated.

    Quote Originally Posted by curious aardvark View Post
    Oh and start thinking and working in millimetres.
    I did my apprenticeship in both mm and inches, can machine to either thous or microns, but I got lazy I'll bear your advice in mind!

    Quote Originally Posted by curious aardvark View Post
    Also how you design the parts makes a HUGE difference.

    Parts designed specifically to be 3d printed will be stronger and mush easier to print than parts you just designed without taking 3d printing requirements into account.
    How do I learn the specifics of "Designing for 3d Print"? I use FreeCAD and am reasonably able with that, but it sounds like there is more to it...are there documents/videos that will help with my design style?

    Quote Originally Posted by curious aardvark View Post
    Probably the best suited to your purposes at the moment would be a flashforge replicator pro 2 - unfortunately It's pretty new and i can't find a UK distributor.
    Thanks...I'll have a look.

    Quote Originally Posted by curious aardvark View Post
    How 'handy' are you with mechanical things ? ie: would you be happy with a build it yourself kit ? as opposed to a ready built machine ?
    Pretty handy...before I got into computer networking (I'm a freelance consultant) I was a ships engineer...you got to be handy when you're thousands of miles from anywhere and something breaks A kit sounds like additional fun!

  4. #4
    You wrote "Probably the best suited to your purposes at the moment would be a flashforge replicator pro 2 - unfortunately It's pretty new and i can't find a UK distributor."

    I went on the FlashForge site, found a FlashForge Creator Pro 2, but no Replicator. I also found a MakerBot Replicator 2....did you mean flashforge replicator pro 2?

  5. #5
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    Quote Originally Posted by JimB View Post
    How do I learn the specifics of "Designing for 3d Print"? I use FreeCAD and am reasonably able with that, but it sounds like there is more to it...are there documents/videos that will help with my design style?
    This wisdom is going to largely come from hands on experience. You might find some stuff to read and learn a little on the subject but you will really learn when you print an object 12 times in as many different ways for yourself. Some filaments have different qualities and so are better for different functions. PLA for example is a great looking filament. It makes great shelf trinkets. But PLA loves to separate at the layers. So you can always take anything printed from PLA and throw it to the floor and it WILL break at the layers. This is an important piece of information we can take away a few things from. First We should plan to print our object so the way it gets loaded is not going to stress or pull apart the layers. And also this very much tells us that maybe PLA is better for things like lithophanes or busts or figurines. But for actual functional parts we should look to better filaments that will not separate at the layers. PETG for example has layer separation problems opposite to that of PLA. With PETG if we print on bare glass we will break the glass trying to separate the print from it. PETG will break right through the layers each and every time. And so we will find a lot of functional printed parts we can buy on this here internet are printed from PETG. I am years into forcing my 3d printers to reinvent themselves regularly. The best thing you can do is just jump into the fray and try a bunch of different things paying attention to your results along the way. There is also a huge thing with infill density and perimeters or wall thickness and designing your part with these things in mind along with the idea of where your part needs its strength. You just have to pick a starting point and make sure you share your successes with the group.

  6. #6
    Anyone who cites experience as the greatest teacher gets my vote! I have gained some valuable insight from your post, AutoWiz, and for that I thank you! I'm ready to dig into this subject, and it looks like I have found the forum where the knowledge lies (been to others and dind't get replys, let alone answers )

  7. #7
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    Quote Originally Posted by mobilemovie View Post
    Who is the best printer?
    The best printer is Spegelius because he actually prints in color. Unlike some of us posers and wannabes out here. But one day we will rise up and our dilapidated attempts will gel together and a true multi material print will emerge out of all the plastic mess. No matter how much money it costs!

  8. #8
    Super Moderator curious aardvark's Avatar
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    yeah It's the pro 2 - my mistake :-)

    The thing with 3d printing is two fold:
    1) How you actually orient the print on the build plate. This determines which direction the print is strongest in.
    2) how well designed it is. If I'm designing something from scratch I design so i do not need supports. The only time I've used supports in the last 8 years, was when reverse engineering broken household widgets.

    It's all about overhangs, underhangs, layer height and how far you can build out each layer.

    The speed and temperature and materials used also have a significant impact.

    You'll see a lot of people printing pla at 18-190c. They also winge on about layer bonding not being great or pla being brittle.

    Print it at 200-210c and neither of those things is correct

    I designed some 20x20 'aluminium extrusion' and printed it vertically. When snapped - and none of us could do it in our hands. It broke on a diagonal line - not long layer lines.
    https://www.thingiverse.com/thing:4334960/files

    So 3d printing is as much as art as it is a science.

    So the chemical and physical properties of the extruded plastic is the science part.
    The print speed, cooling, design and quirks of your individual printer is where the experience and art come into it.

    Basically you are building something from the ground up - in tiny layers.

    Now if you have a part that starts printing in mid air - or just sticks out at a right angle - you can print supports.
    The advantage of the pro 2 is that it has two independant extruders.
    So you can load one with pla or whatever and the other with soluble support material.

    So you design something, almost as though it were being injection moulded.
    Then remove when done and throw into a sink of warm water and dissolve all the bits that aren't part of the original model.

    If you just want to go down the single extruder route - then I would argue that the twotrees sapphire pro 2 at around £300 is not only the most solidly built printer around, but also one of the veru best - at any price point.
    https://www.ebay.co.uk/itm/TWO-TREES...4AAOSwVktgBb0Z
    Or nearer £500 off amazon.

    There are a couple of mods that are easy and quick to do.
    And you'll have a solid machine that will print faster and with more precision than anything else I've seen or currently know of.
    And it's pretty much silent in operation :-)

    If you're anywhere in the uk midlands, I'm near burton on trent - you're welcome to pop round and see one in operation. I've also got various others that cover the entire gamut of fdm printer types and styles.
    And a laser cutter, if you need any wood or acrylic cut :-)

    I'm personally naturaly immune to corona viruses and have been vaccinated. So I can't catch it from you or give it to you.

    It does help to actually see a printer or 2 in operation and handle a bunch of 3d printed widgets.

    Seing some of the models I have that incorporate print in place hinges and moving parts would probably give you some ideas on designing your thing.
    3d printers will do most things injection moulding does, but it can also do somethings injectuion cant.
    Mechanisms inside sealed casings - for example.

    The first tool that was printed in space was a working ratchet spanner - printed in one go.
    I made one for my space mad mate.
    Neat bit of design.

    Anyway the offer's open :-)
    Last edited by curious aardvark; 03-18-2021 at 02:37 PM.

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