what is the trend in build platforms solutions atm?

Hi guys, I was wondering what is the last trend or what is the short term future going to bring to the build platform?

Forget my noobness but from what I understand almost all printers have a carriage -alu plate or laser cut wood- that serves as the attachment point to the axis the built bed is sitting on, then some spring loaded bolts are used to attach the actual print bed, either heated or not, which is most commonly a sandwitch made of the heating PCB or silicone pads, a quite thick aluminum plate to evenly dissipate the heat and to avoid warping and a borosilicate glass plate to hold the plastic part.

I was wondering what is the most promising solution out there and what are the typical tolerances of the aluminum plates (carriage plate and heat spreader plate)? Can aluminum plates be avoided?

Thanks for joining this discussion.

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Aluminum plates should not be avoided in my opinion. The glass is a thermal insulator and should be avoided. Aluminum gives a much more even heat distribution. Instead of glass, you can use kapton tape, pei, or other surface like Buildtak.

A good plate would be made out of Mic-6 aluminum because of it's flatness.

Glass is the wrong thing to use if you have a heated bed. Many people don't seem to value their time very highly so they try all sorts of things to get prints to stick to the bed instead of spending $30 or so to actually fix the problem. Cast aluminum tooling plate with a layer of kapton, PEI, PET stick to ABS and PLA. Use a well designed 3 point leveling scheme that doesn't bend the plate or the undercarriage and prints sticking to the bed becomes a non issue.

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

PEI is a plastic that negates the need for any spray, glue or other stuff to keep your item on the platform. It also allows easy removal once cooled.

Thanks for your answers.

I've read that PEI is a good option used by some printers. How do you stick PEI to the aluminum? And as far as I know PEI can be used to max 217deg or so. What about printing higher temp plastics? Can one print straight on the aluminum?

Is there any reason to use another aluminum plate for the undercarriage? I've seen laser-cut plywood and also steel (solidoodle3 ?). If one can use the 3-point leveling for the initial setup I guess there is no need for alu carriage.

On the other hand I am thinking about using alu extrusions or alu squares to build the undercarriage because I will use flanged bearings that it will slide through and I need some degree of linearity. I am thinking something like this holonomic drive built or maybe this Lathon 3D Printer? I am wary about the play induced by the connection pieces or brackets.

The bed I am thinking of will slide through bearings on plates about the way you see in this pic, floating basically and I am having an urge to use the aluminum plate ITSELF to slide through the bearings. I know this might be an awful idea but besides the fact that it expands and contracts with heat, its flatness would ensure a smooth sliding if there was some sort of spring loaded excentric on one of the bearings to compensate for the expansion in thickness due to heating up.

Edit: just did a quick sketch of a solution using square tube and (flanged) bearings -flange not shown in this render:


The square tubes can be rotated 45deg and with 2 bearings the flanged bearing can be avoided but this was quick for me to throw together.

Edited 3 time(s). Last edit at 09/18/2015 06:57AM by realthor.

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The bearings are usually attached to the undercarriage, if that undercarriage warps or bends due to either a poorly designed leveling system or heat, it will affect how the bearings slide on the guide rails (if used) and the position of the bed plate. Wood and derivatives such a MDF will warp (quick) when put near a heated surface. Plywood will warp (quick) and delaminate (over repeated exposures). Aluminum is stable.

The coefficient of thermal expansion of aluminum is 22.2 um/(m K). That applies to all dimensions. If the plate is 6.35 mm thick, it will expand by 7 um over a 50C temperature rise. Thermal expansion of an aluminum bed plate in the Z dimension does not exist for 3D printing purposes. Besides, proper preparation of the printer is to zero the bed when it and the extruder are at print temperature.

Your drawing shows what is essentially one bearing on each side of the moving plate. The plate will wobble back and forth as it moves. It needs two bearings spaced along one side to ensure that it stays aligned with the axis of the square tube, and a single bearing on the other side to provide roll (not rolling) stability. Its the same reason that two guide rails are used with 3 bearings (or 4 if the designer isn't very experienced). As soon as you add that second bearing on one side you have to lengthen the guide tubes to accommodate the extra space between those bearings.

Using tubes for the undercarriage is fine as long as they can be kept solidly locked to each other without warping/twisting, etc. I would not trust plastic corners to maintain the required relationship between the tubes.

Look at the printer linked in my sig, below, step #7 to see how to do a proper 3 point leveling system. While you're at it, look up "linear guides" on ebay. For about the same cost as all that aluminum tubing, wheels, bearings, you can get industrial quality, used, parts that will be far better than anything you can cobble together.

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

I know that I can buy industrial-ready stuff either used or new but I am trying to do something that can use readily-available parts, and those kept to a minimum too.

Frankly If the build plate must be aluminum by all means then I would really like to use it alone as the guide and have the bearings roll on it. If there is no thermal expansion on Z then the plate has to have some room to expand in X and Y direction, which can be introduced into the carriages design. 7um/50deg (0.007mm) is not much and if i don't use linear bearings - which have tighter tolerances-, this can be accomodated by radial bearings without any additional clearance.

Moreover, if the homing or calibration is done after the plate has reached the work temp then this should not have any side effect on the print.

I get what you are saying about having 2 carriages on one side and one on the other. It makes sense and i am glad you pointed it out.

My worry is that the Mic-6 is a rather soft material and the bearings will dig into the plate with time. I am planning to use this setup for Z axis so the movement will be slow and there shouldn't be much wear but I don't have much experience in this so any additional discussion/advice is welcomed.

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For you, is a 3D printer a hobby in and of itself, or is it a tool with which to pursue other interests?
What is the main goal you're trying to achieve with regard to the printer's performance?
Does the method you have chosen lead to that goal?

Steel on aluminum is usually not a good idea. Bearings in contact with a heated bed will get hot and the grease in them will melt and probably ooze out of the bearings all over the bed plate. You'll forever be cleaning grease off the bed plate (if you can) so that prints will stick. 3D printers produce a lot of small bits of plastic trash that will find their way under the bearings and make movement rough or will cause binding.

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My preferred bed material is glass on top of aluminum. I wouldn't want to print directly on an expensive aluminium tooling plate because of the risk of damaging it. Also, I can remove the glass bed with the print on it and start another print immediately, then run cold water over the back of the glass or put it in the freezer to make it easier to remove the print. The temperature drop.across the glass is 5C to 10C so not a significant problem.

I prefer the delta architecture to Cartesian architectures because of its simplicity and the non-moving bed. For a really large printer, Hbot or CoreXY might be more practical.

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Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

So far it is a hobby, I don't yet have a need for a 3d printer that will print 24/7. I am more of a reprap enthusiast.

Steel on aluminum has been done on other printers and on some DIY CNC machines and, as I mentioned, I am trying to design this for Z, so the wear will be minimal. These vitamins, bearings and Alu square tube are ubiquitous and the tube is fairly linear. I haven't seen T-slot or V-slot besides specialized online shops or ebay/aliexpress so i'd rather stay away from those for now. One can use bearing sleeves to prevent the aluminum from caving in by plastic deformation but those will wear themselves and their wear must be factored in when considering precision. I don't think sleeves are a good idea, I am still aiming for an as good precision (and repetability) as possible.

Heat transfer in the bearings, on the other hand, is something I didn't see coming. This might be an issue with my attempt to minimize vitamins and I'll have to resort on separating the functions again, the way things are now with a carriage frame supporting the hotbed.

Debris and particles could be kept out by having a sort of scrubbing foam piece that swipes the surface as the platform moves. I don't know to what degree this would work, it is just an idea. Or having two bearings rolling on the corner of the aluminum square tube.

I see that MIc-6 is an Alcoa-patented product and i don't know about the availability of this in different parts of the world. I am based in Europe and so far am not aware where can I order such a plate around here. Is there any good alternative to this?

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Quote
realthor
I see that MIc-6 is an Alcoa-patented product and i don't know about the availability of this in different parts of the world. I am based in Europe and so far am not aware where can I order such a plate around here. Is there any good alternative to this?

This is from a site I ordered my plate from...

Quote

Cast Aluminum Tooling Plate or Jig Plate
Is known by various trade names:
Mic 6® (a registered trademark of Aloca Inc)
Alpase K100-S® (a registered trademark of TST, Inc)
Alca 5™ (a trademark of Aluminum Company of America)
Vista Metals ATP 5™ (a trademark of Vista Metals Corp.)
Alimex 5083

MIC-6 is a brand name. Just look for cast tooling plate or jig plate. The stuff is used to make jigs and fixtures in literally every machine shop on the planet. It is not expensive stuff. My local Speedy Metals will sell a 12" x 12" x 1/4" plate for $40. Ebay is full of jig plate squares and discs for similar prices. How does that compare cost-wise to a "heat spreader" + glass? How much is the added reliability of the cast plate worth? How much is your time worth?

Cast tooling plate is not fragile, and damage from things like extruder crashes is inconsequential. You may get a surface scratch that is visible, but it won't have any meaningful effect on the print quality because the scratch on the plate is covered with Kapton or other tape. Glass, on the other hand, can break into sharp pieces that can injure you. Clamping glass to an aluminum plate puts the extruder at risk of banging into the clamps, and increases the moving mass. Glass being a thermal insulator doesn't help your prints stick to the bed, either.

I use my printer almost daily and have yet to run into a situation where I need to start another print so quickly that I can't wait for the machine to cool down to remove the last print. Maybe if I were running a commercial prototyping operation the story would be different, but for 99.9% of people with 3D printers, there's no need to swap build plates. I think the whole swapping-plates thing was a marketing ploy by cheapo kit makers to allow them to use a cheap, thin, not-very-flat "heat spreader" instead of equipping the machines with a proper plate. Also, by removing the plate from the machine to separate the print from the plate, it is less obvious how poorly built most machines are (force applied to remove the print from a proper bed plate would have the machine's frame and rails flexing all over the place). There's nothing that says you can't swap aluminum plates if you really have to have the ability to swap build plates, and an aluminum plate doesn't come with the risk of cutting you or your kids if you drop it. If I ever start feeling like I just can't wait, I'll add a fan or two to the machine to blow room temp air over the build plate and add gcode to my files that turns the fan on after a print has finished.

Here's a print that completed last night- ABS, 240 mm diameter, stuck perfectly to the bed, no warping and no delamination. The build plate is 1/4" cast tooling plate covered with a layer of clean, 5 mil kapton tape. Only two of the 3 screws are used to level the plate, and they haven't been touched in months. The print chamber is enclosed by a PIR foam insulation board on the top, back, and bottom, and 1/8" polycarbonate sheet on the sides. Temperature inside the build chamber is 45C when printing, with all heat supplied by the bed plate and extruder heaters.







Edited 2 time(s). Last edit at 09/19/2015 10:59AM by the_digital_dentist.

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

Quote
realthor
I've read that PEI is a good option used by some printers. How do you stick PEI to the aluminum? And as far as I know PEI can be used to max 217deg or so. What about printing higher temp plastics? Can one print straight on the aluminum?

Use 468MP transfer tape. You can find sheets on Amazon. Search for "TapeCase 468MP". I bought 12' x 12' sheets.

When using the tape, or other adhesive cover, you can try using the wet method for aligning it. Spray the surface with soapy water (I use window cleaner with no problem). Once the surface is wet, apply the tape. It won't stick and you can get it positioned where you want it. Then use a squeegee, credit card, etc, to squeeze the water out. The tape will then stick and stay. I have used it with Kapton, Buildtak, and another type Printerbot used to sell, with no adverse effects.

Wow that is a really good setup. Very professional and expensive looking . Personally I don't aim for expensive nor very specialized because there is a cathegory of people that need to be able to have access to or build themselves cheaper machines that use clever workarounds to achieve a reasonable repetability/precision.

Thinner alu plate (tooling or similar) + removable glass or similar engineered plate would work for me as long as the loss of flatness is insignifiant compared to the other parts where the printer looses precision due to the various compromises that would keep it in reprap theritory and/or cheaper/affordable price.

My intention is to use an as light as possible -in terms of involved layers- to slide back and forth through carriages with bearings. This is to avoid linear rods or other expensive or not easily available "industrial" solutions. This discussion has somehow sent me back to square one in that I will still use a carriage frame and a separate layered hotbed with heating PCB or silicone pads, aluminum plate and glass or PEI/Buildtak.

I could use a tooling plate with a PEI layer as a single layer bed only if I plan to have it print PLA without heating it. But that somehow drastically limits the choice of materials I can print with.

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It sounds like you're trying to design a printer for "the masses" - people who have neither money nor access to tools, who can take a shopping list to Home Depot, buy all the parts, and assemble the thing with duct tape and supe glue. But why would such people be interested in having 3D printers? They don't make anything- that's why they don't have tools.

I don't want to trample your dreams of 3D printer fame and fortune, but if there were an easier, cheaper way to make a printer that works, there would already be 20 Chinese companies making them. The low end of the market is already saturated with crappy kits that don't work well- they look like a 3D printer when assembled and have all the feature boxes checked off, but they don't deliver on the promise. Unless you have a factory where people will work for pennies per day or prisoners to build your kits, you'll have a hard time competing in that space.

As far as parts availability goes, industrial parts are manufactured in huge quantities and widely available. You need a 15mm linear guide? I can show you 20 suppliers on the first page of a google search. I think when you say "availability" you're confusing availability with price. You don't mean available as in lots of suppliers with ready stock. You mean cheap.

How does someone with no 3D printing experience get the idea they can take on the whole 3D printing industry by designing a cheaper, better printer? I think you better try crawling before you enter a marathon. It would be a useful exercise to "invest" in one of the $300 kits to see how truly awful they are. Once you have a little experience, you can then start thinking about other ways to do things that make some sense. If you're going to develop a super cheap but super good printer, you'd better have some funds set aside for development and access to a good shop full of tools. Developing a $200 printer costs more than $200.

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

You are completely right, building a cheap printer is most likely an exercise that is going to dissapoint pricewise and it will end up costing a lot more than the desired price. But trying to achieve that can bring up many useful ideas and, more important for me, many issues I don't see right away. Once I get aware of those I can either decide to go for better parts or a different solution. It's cheaper for me to crowdsource the wisdom and experience than to buy a 3d printer and see with my own eyes.

Also buying an ultimaker will not help my case, let alone a cheap chineese prusa or some solidoodle knock-off.

I think that all responses in this thread have been helpful and I came to realize that a separate support plate or carriage is absolutely necessary if a hotbed is to be involved, otherwise the tooling plate itself could be used with a PEI/etc surface stuck to it to reduce the complexity. Maybe the only way is to prototype it and get some numbers. But I'm quite far from that point so until then i am welcoming any further discussions on this matter.

Edited 1 time(s). Last edit at 09/19/2015 04:36PM by realthor.

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Question: if a heated bed is involved and an enclosed chamber is built around it to have 40-50deg inside for printing with plastics that require this, isn't any kind of bearing grease going to melt? As far as I know, all bearings have to have some kind of grease to properly function.

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Quote
realthor
Question: if a heated bed is involved and an enclosed chamber is built around it to have 40-50deg inside for printing with plastics that require this, isn't any kind of bearing grease going to melt? As far as I know, all bearings have to have some kind of grease to properly function.

You will have to use the right grease, there are a few to chose from
Igus makes grease free bearings that work in very rough environments but the tolerances are not that great.

Edited 1 time(s). Last edit at 09/20/2015 02:57AM by SlowFoot.

So if i use the right type of grease in the radial bearing with a proper seal then the grease will not melt and the soot/whatever debris will not go inside the bearing even if i choose to roll the bearings straight on the tooling plate's edges right? I know there are bearings that can be used in very rough or hot environments I just have to find a way to have normal bearings work in 50-100ish celsius range.

Edited 3 time(s). Last edit at 09/20/2015 06:27AM by realthor.

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Whats the best/preferd method of heating the tooling plate?

Quote
realthor
So if i use the right type of grease in the radial bearing with a proper seal then the grease will not melt and the soot/whatever debris will not go inside the bearing even if i choose to roll the bearings straight on the tooling plate's edges right?

I don't think you'll have a problem with bearings running inside a warm build chamber (I've been doing it for years), just bearings that are in contact with the much hotter bed plate. I also don't think you'll have a problem with printer crud getting inside the bearings, just between the bearing and the plate. I have never tried to remove and replace grease seals in ball bearings, but I suspect you'll find it pretty difficult without some specialized tool(s).

Quote
wetsparks
Whats the best/preferd method of heating the tooling plate?

There are three types of commonly available heaters- printed circuit board heaters, silicone type heaters, and kapton heaters. The kapton heaters have the lowest mass so are probably better for beds moving in the Y axis. I'm not sure how good the PCB heaters are- the hot side of the board (where the copper traces are) will expand more than the other side so I think it will warp when heated, but maybe after it reaches a stable temperature it will flatten out again. Silicone heaters are highest mass, I think, so better suited to machines where the mass of the bed doesn't matter, such as machines where the bed doesn't move or only moves in the Z axis.

The most important thing about the heater is to ensure that it has adequate power to get the bed temperature well above print temperatures and to do it reasonably quickly. If the thing takes 20 minutes to aproach print temperature (who wants to wait that long?), your controller won't be able to regulate the temperature very well. You want to use PID control to regulate the temperature because maintaining a tight tolerance on the temperature is good for print quality. PID control doesn't work if the time constant of the whole system is too long. As a point of reference, my 12" x 12.5" x 1/4" aluminum plate has a 450W heater and gets up to 105C ABS print temperature in about 5 minutes. It can get much hotter. When printing the controller reports no variation in temperature (only displays 1C increments). Use a relatively high powered heater and make sure the power supply for it can deliver the power it needs.

I've seen a lot of posts about bed heaters being sold by cheapo kit makers not getting up to print temperature or only getting there after 1/2 hour or so. The usual solution is to crank up the power supply voltage (if you can), but then you risk burning up the power supply because the kit makers provision the kits with a just barely adequate supply (to keep cost down). Another common problem is burned up PCB traces that switch the bed heater current. Ultimately, the safest bet is to use a separate, adequately spec'd power supply for the bed heater and switch power to it using an SSR.

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

Have a talk with a official reseller for one of the three letter bearing makers (INA, SKF, FAG aso) or two, what you need is in not that extreme. And check out the Igus program, they have a lot of interesting stuff that is inexpensive too.
Custom made silicone heating pads was resiliently up in another thread.

Thanks for the reply d-d, I have just completed the build of my new printer, a Prusa esk, reprap ish printer. Its a cube extrusion frame with twin Z motors and ramps 1.4. Oh and twin extruder. For the heated bed I've been using one of the Red Mk II hot beds with a glass plate on top, but have had nothing but problems getting the prints to stick, such an uneven heat distribution, even with a bucket load of thermal paste between them! Never had this problem with me old printer, DaVinci 1, but then they used a Kaplon heater stuck to the glass plate.

I've looked at Kaplon heaters in the 200 x 200 range but they only seem to be about 140 watts, a silicone one of the same size comes in at 200 watts so that's what I've ordered. Also got on order a chunk of machined ally plate 250 x 250 x 10 mm. Got a small mill that I've CNCed so will have to get the fly cutter going to thin it down, probably to around 5 mm.

Looking forward to solving this problem now

What do high temp bearings have differently besides the grease? What happens with a normal bearing different than a high-temp bearing during high-temp stress? There are ways to replace the low-temp grease of a normal bearing with hight temp grease but I don't know how a normal bearing would react to a higher temperature: would that damage it or maybe the balls would expand more than the race and they will get stuck or maybe something entirely different. What are your toughts/experience?

Whatever the answer I think it is worth trying at some point. If it is not enough to replace the grease then comparing the price of the needed specialized bearings with the alternative of buying the aluminum carriage would show which one make sense.

EDIT: ok, until someone picks up the previous question I'll trow in some more ideas: what about having an aluminum corrugated panel as a build plate; it's light and I assume they can be very sturdy and flat too. I don't really know about their availability though. I was wondering how the hollow channels could be used to somehow heat the bed. Here's a pic of what I am talking about:



Edited 2 time(s). Last edit at 09/21/2015 09:45AM by realthor.

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Searching for related info online I have found some answers that could put to rest my questions above:

1) the heat transfer in the metal bearings and the hard rollling contact between the steel bearing and the aluminum plate can have a workaround in having some nylon bearings instead. According to info.craftechind.com/:

Quote
info.craftechind.com
Plastic bearings do not transfer heat to other areas of the mechanical assembly.[...]
Nylon is quiet in operation, resists abrasion, wears at a low rate, and is easily molded, cast, or machined to close tolerances. Improvement in mechanical properties, rigidity, and wear resistance is obtained by adding fillers such as graphite and molybdenum disulfide to nylon. While the maximum recommended continuous service temperature for ordinary nylon is 170°F, and 250°F for heat-stabilized compositions, filled-nylon parts resist distortion at temperatures up to 300°F.

2) I have found that Felix 3d printer has such a corrugated panel printbed albeit not heated:
Felix 3.0 printbed

I don't think it's an all-metal aluminum lattice core panel but it's a good start that is proving that it is feasible. I wonder if NiChrome wire couldn't be routed in a fashion similar to the DIY heateds bed i've seen done before.

Regards.

Edited 1 time(s). Last edit at 09/23/2015 12:55PM by realthor.

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