Cupcake CNC update

Hello to everyone!

I own a pretty old Cupcake CNC printer from Makerbot (one of the first ones actually):



with a Makergear stepper-driven extruder (Stepper Plastruder it was called), this one:



Because Cupcake original design had a DC motor extruder MK3 I had to modify extruder board firmware to control the stepper motor (I am a programmer). It had a pair of nice H-bridges that worked fine to run the stepper.

Now, that I have an old basically wooden 3D printer with ball screw driven Z stage (which actually stinks), I decided to rebuild it into something working good. I will keep the stepper motors and the Makergear extruder, the rest needs rebuilding.

1. For the XYZ part I am looking at Makergear M2 design. Essentially, this:



It seems quite easy to follow. Linear guides for X and Y stages, linear bearings for the Z stage etc etc, I can get all that off Aliexpress. Metal frame -- quite easy to cut either from steel or aluminum. What do you people say? Is the M2 mechanics a decent layout for a 3D printer? I would like it to be steady, not the wooden cheesy stuff I have in my Cupcake. By any chance, does anyone know the diameter of vertical metal rods that the Z-stage is sliding on in M2?

2. Electronics. My Cupcake CNC has a board labeled "Reprap motherboard 1.2" with an SD card reader. This is probably one of the oldest ones. Also I have a separate board for the extruder/hotend and also 3 boards for every stepper motor. Someone on IRC told me it's good to print "volumetric" these days which my board does not support. It would be very nice to have a single board for everything, to plug in all the steppers and extruder hotend, also endstops support would be nice. I would like to upgrade to the latest electronics. What would you suggest I upgrade to?

3. The extruder. My extruder's nozzle is 0.4mm and it seems too big for my purposes. I would like to print small plastic parts, e.g. mobile phone battery case, or panel for mobile phone etc. Should I get another extruder? What model? What are the currently best precision extruders? The problem with extruders I had, seems they produce some extra material after they are stopped which creates a sort of a plastic spider-web (oozing?). Are there extruders with a valve that cuts plastic immediately? Or maybe it is possible to modify the nozzle of my extruder? Due to its desing I don't think it would be possible to replace the nozzle by a smaller one at this point.

4. I saw double-head extruders on the internet. What is the point of that? Printing two copies of the same model simultaneously? Should I get that?

So, my questions essentially are:

1. XYZ mechanics layout - which one?
2. Electonics - what board? Volumetric printing?
3. Extruder model to print small parts.

Thank you very much!

Edited 5 time(s). Last edit at 03/09/2014 06:48AM by AngelOfGrief.

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AngelOfGrief
1. For the XYZ part I am looking at Makergear M2 design. Essentially, this:

m2axes.png

It seems quite easy to follow. Linear guides for X and Y stages, linear bearings for the Z stage etc etc, I can get all that off Aliexpress. Metal frame -- quite easy to cut either from steel or aluminum. What do you people say? Is the M2 mechanics a decent layout for a 3D printer? I would like it to be steady, not the wooden cheesy stuff I have in my Cupcake. By any chance, does anyone know the diameter of vertical metal rods that the Z-stage is sliding on in M2?

The cartesian setup of the M2 seems quite good, especially since it is using proper linear guides. I built a delta-style printer using Misumi linear guides (more expensive than the Chinese-made ones, but supposedly better quality) and they are very nice to work with. Much quieter and stiffer than rods and linear bearings. I don't know the diameter of the Z smooth rods, but I would personally use at least 12mm diameter rods, considering the Y axis and bed are cantilevered off of these rods.

Quote
AngelOfGrief
2. Electronics. My Cupcake CNC has a board labeled "Reprap motherboard 1.2" with an SD card reader. This is probably one of the oldest ones. Also I have a separate board for the extruder/hotend and also 3 boards for every stepper motor. Someone on IRC told me it's good to print "volumetric" these days which my board does not support. It would be very nice to have a single board for everything, to plug in all the steppers and extruder hotend, also endstops support would be nice. I would like to upgrade to the latest electronics. What would you suggest I upgrade to?

My first printer was a self-sourced and built McWire using the Gen 2 electronics. My setup was pre-Motherboard 1.2, so it was based on an Arduino with an ATmega168. Yours is based on the ATmega644P (like the Sanguino), which has much more space available for programming. There's no reason you can't use a modern firmware with volumetric extrusion on this hardware, though you may not be able to use all features at the same time such as SD card reading, LCD display, EEPROM, etc. Modern firmwares don't support the separate extruder board with its own Arduino (you probably have this board or similar?), so you would need to do some modifications to have the Motherboard bypass the Arduino on the extruder controller. Or, another possibility is to retain the Arduino there as an extruder controller and modify/write firmware to take advantage of it.

The easiest (but most expensive) option is to just replace the whole electronics set with something more modern. Most people recommend RAMPS, as it has a multitude of features, great expandability, supports dual extruders out-of-the-box, and is relatively inexpensive. There are other, cheaper setups, but most don't support dual extruders.

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AngelOfGrief
3. The extruder. My extruder's nozzle is 0.4mm and it seems too big for my purposes. I would like to print small plastic parts, e.g. mobile phone battery case, or panel for mobile phone etc. Should I get another extruder? What model? What are the currently best precision extruders? The problem with extruders I had, seems they produce some extra material after they are stopped which creates a sort of a plastic spider-web (oozing?). Are there extruders with a valve that cuts plastic immediately? Or maybe it is possible to modify the nozzle of my extruder? Due to its desing I don't think it would be possible to replace the nozzle by a smaller one at this point.

Modern firmwares support retraction, acceleration, etc. which pretty much eliminates the oozing and blobbing that was common on those older machines. Modern extruder designs aren't really any better than what you have. In fact, many people still use geared stepper motors just like the MakerGear extruder you have has. With your hot end you should just be able to replace the nozzle with a smaller diameter one. Double check, but I think that MakerGear still uses the same thread barrels (M6) that they used to. I'm sure MakerGear would be happy to help you with any questions you have on it since your extruder is originally from them. The old MakerGear hot ends are still good quality, though maybe a bit more oozy than modern J-Heads or similar because of the larger melt zone. I would still be using the MakerGear hot end I had from a while back if I hadn't cross-threaded the PEEK threads when disassembling it to clean it up.

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AngelOfGrief
4. I saw double-head extruders on the internet. What is the point of that? Printing two copies of the same model simultaneously? Should I get that?

I use dual-extruders on my machine. It's great for printing dual-colored objects (more for show than anything else, as this print on my machine shows), or for using dissolvable or break-away support material (useful for complex parts). There's a fair amount of information on printing with more than one nozzle, though it is still highly experimental at this point. It is probably the slowest advancing tech on RepRaps, just because it isn't easy and the software implementation (on the slicer side) is rather difficult to get right.

So, tl;dr:

Quote
AngelOfGrief
1. XYZ mechanics layout - which one?
2. Electonics - what board? Volumetric printing?
3. Extruder model to print small parts.

1. This is up to you. The M2 design is nice, and that printer has lots of excellent reviews. Having just one Z motor without having to use belts or anything is nice too.
2. This is also up to you. Cheap, but more work? Use your existing electronics and do some firmware/hardware work. Or easy, but more expensive? Buy new electronics, such as RAMPS.
3. There's no reason to change the extruder you have. Just swap out the nozzle for one with a finer orifice. If you really want to switch hot ends, a J-Head or similar should be a direct swap with the MakerGear hot end.

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I've got a Cupcake with Stepstruder as well. I ended up replacing the Makerbot electronics with a RAMPS 1.4 board so I could run Marlin and stay relatively up-to-date with the latest firmware. I did have the stepstruder working with the MBI extruder controller (I had the flying leads soldered on, and a Pololu on a daughtercard), but it was pretty sketchy. Running the Marlin firmware I have less of an ooze issue, mainly because of the new support for retraction. I have not moved to volumetric extrusion yet (although this sounds very promising).

It's printing reasonably well in PLA now, the biggest issue I have is the Z ribbing. And the small build envelope. While I'm waiting for my 2UP to arrive (any day now! :-) I'm searching for printer designs where individual pieces fit on the tiny build plate -- I plan to reuse the extruder/hotend and the RAMPS board and that's about it.

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Gord Broom

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gjbroom
I'm searching for printer designs where individual pieces fit on the tiny build plate

The majority of printed parts for most printers are small enough to fit in a 100x100mm build area, but there's often a part or two that doesn't fit. All the parts for the Wallace or Printrbot are small enough to fit in a 100x100mm build area. I think that all of the standard Prusa i3 parts are small enough. All the parts for the Mendel90 may fit as well, with the exception of maybe the spool holder.

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Quote
NewPerfection
The easiest (but most expensive) option is to just replace the whole electronics set with something more modern. Most people recommend RAMPS, as it has a multitude of features, great expandability, supports dual extruders out-of-the-box, and is relatively inexpensive. There are other, cheaper setups, but most don't support dual extruders.

Thank you very much for all your answers.

I think I will use my old Atmega 644P board and I'm really glad I can get rid of the extruder board. I have found the schematics to this board on this website and it looks essentially there isn't anything on it except for the CPU itself. And it does have an i2c header to drive an LCD. I'll take a look at RAMPS 1.4 schematics now.

p.s. Just found M2 Z-stage assembly manual:

[cdn.shopify.com]

Looks like they use 10mm linear shafts and linear bearings.

Edited 1 time(s). Last edit at 03/11/2014 04:28AM by AngelOfGrief.

I recently completed upgrades on a loaned Cupcake CNC . the only part of it left is the frame, motors and the heated bed I made an TwoTimes x/y lowrider for the x/y stage and eliminated the MBI electronics for a Ramps 1.4 setup. I also made and installed a MiZrider (less work than a twotimes Z-Rider). I also use a J-Head MK IVB and a Wade's Accessible extruder. Lastly, I installed a 30A 12VDC LED type (meanwell) power supply since ATX PSU's aren't ideal.

The new Franken-Cake as I call it prints at .1mm layer resolutions at 60mm/s (fastest I've tried so far) just as well as the Replicator 2X that's pictures next to it. You don't have to upgrade the frame to get a Franken-CAke to print VERY well. Just the fact that I'm no longer tied to Skeinforge and Rep G is awesome! I can use Cura, Slic3r, Kisslicer, etc.I'll post a closer picture when I get home.

GIBroom, you can print a 3DR Simple or a Tantilus on your Cupcake. I printed every single part for a 3DR Simple by JohnSL on my Modified Cupcake. I also experienced bad Z-banding/ribbing issues and I had the ACME rod upgrade installed too (no threaded M8 rods). That eliminated the wobble but the fact that couldn't print at full step heights due to the SAE thread pitch on my ACME rods meant I had some Z-Banding. I printed up and installed a MizRider from thingiverse and all of those problems were eliminated.

Edited 2 time(s). Last edit at 03/11/2014 12:52PM by umdpru.

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AngelOfGrief
I think I will use my old Atmega 644P board and I'm really glad I can get rid of the extruder board. I have found the schematics to this board on this website and it looks essentially there isn't anything on it except for the CPU itself. And it does have an i2c header to drive an LCD. I'll take a look at RAMPS 1.4 schematics now.

Take a look at the Sanguinololu schematics, as the Sanguinololu is based on the 644P (which is pin-compatible with the 1284). If you wire up everything in the same manner as the Sanguinololu, you won't have to do much in the way of firmware modification to get Marlin or Repetier or whatever running on it.

Quote
umdpru
I recently completed upgrades on a loaned Cupcake CNC . the only part of it left is the frame, motors and the heated bed I made an TwoTimes x/y lowrider for the x/y stage and eliminated the MBI electronics for a Ramps 1.4 setup. I also made and installed a MiZrider (less work than a twotimes Z-Rider). I also use a J-Head MK IVB and a Wade's Accessible extruder. Lastly, I installed a 30A 12VDC LED type (meanwell) power supply since ATX PSU's aren't ideal.

The new Franken-Cake as I call it prints at .1mm layer resolutions at 60mm/s (fastest I've tried so far) just as well as the Replicator 2X that's pictures next to it. You don't have to upgrade the frame to get a Franken-CAke to print VERY well. Just the fact that I'm no longer tied to Skeinforge and Rep G is awesome! I can use Cura, Slic3r, Kisslicer, etc.I'll post a closer picture when I get home.

GIBroom, you can print a 3DR Simple or a Tantilus on your Cupcake. I printed every single part for a 3DR Simple by JohnSL on my Modified Cupcake. I also experienced bad Z-banding/ribbing issues and I had the ACME rod upgrade installed too (no threaded M8 rods). That eliminated the wobble but the fact that couldn't print at full step heights due to the SAE thread pitch on my ACME rods meant I had some Z-Banding. I printed up and installed a MizRider from thingiverse and all of those problems were eliminated.

That is very cool. MakerBot didn't do a very good job of engineering the Cupcake, despite the fact that the basic design was usable if more thought had been put into it. The only Cupcakes that I've seen that printed well at anything above 15mm/s were heavily modified.

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OK, now deciding on the electronics upgrade on my Cupcake. Missed some action lately, so I need some confirmation if I got this right, please:

1. "Gen 7 electronics" found on this website is a board with an Atmega 1284P MCU which relies on 4 Pololu drivers to drive the steppers. Pololu's are plugged into it. So, it's basically an all-in-one-board 3D printer controller.

2. RAMPS 1.4 is a board that also needs 4 Pololu's plugged into it, however, it does not carry an MCU and needs an external MCU board. The advantage of RAMPS 1.4 is I can later use newer MCUs w/o replacing the rest of my electronics.

3. My Cupcake has some "v2.3 stepper drivers". The only difference I found with Pololu's is my boards do not have half/quarter etc step support and sleep ability. Also they are somewhat bigger. How exactly useful is half-stepping? Is it really necessary?

Sanguinolulu -- essentially the same as "Gen 7 electronics"?

A4988 drivers can be obtained from Chinese suppliers and they are like 4 times cheaper than on Pololu website. Are they reliable at all?

So, I can keep my old Atmega 644P MCU, all I need is purchase a RAMPS 1.4 board and 4 Pololu's, then I can run any modern up-to-date firmware available on the net. Is that right?

Thanks again, I'm getting there.

Edited 3 time(s). Last edit at 03/12/2014 05:29PM by AngelOfGrief.

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AngelOfGrief
1. Gen 7 electronics found on reprap.org website is a board with an Atmega 1284P MCU which relies on 4 Pololu drivers to drive the steppers. Pololu's are plugged into it. So, it's basically an all-in-one-board 3D printer controller.

Yep, but you can only buy it from one source - Traumflug himself. Otherwise you have to create the PCB and source components yourself.

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AngelOfGrief
2. RAMPS 1.4 is a board that also needs 4 Pololu's plugged into it, however, it does not carry an MCU and needs an external MCU board. The advantage of RAMPS 1.4 is I can later use newer MCUs w/o replacing the rest of my electronics.

That's the idea. However, RAMPS 1.4 is made to be 5V-logic compatible. The newer, more powerful Due (Arduino's Mega-equivalent high processing power MCU) uses 3.3V logic. This requires some changes to RAMPS. See [reprap.org] and [forums.reprap.org]

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AngelOfGrief
3. My Cupcake has some "v2.3 stepper drivers". The only difference I found with Pololu's is my boards do not have half/quarter etc step support and sleep ability. Also they are somewhat bigger. How exactly useful is half-stepping? Is it really necessary?

Odd, the older V1.2 Stepper Motor Driver supported half-stepping. Anyways, the microstepping capability can dramatically reduce the noise produced by the steppers as well as smoothing out the movement. It can also increase movement resolution somewhat. Most people use 16x microstepping simply because it is available on the common Pololu-compatible drivers.

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AngelOfGrief
Sanguinolulu -- essentially the same as "Gen 7 electronics"?

Similar, but not protected by a non-commercial clause.

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AngelOfGrief
A4988 drivers can be obtained from Chinese suppliers and they are like 4 times cheaper than on Pololu website. Are they reliable at all?

They usually are. There is always the possibility of getting defective parts when not ordering from a known source though.

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AngelOfGrief
So, I can keep my old Atmega 644P MCU, all I need is purchase a RAMPS 1.4 board and 4 Pololu's, then I can run any modern up-to-date firmware available on the net. Is that right?

This would probably work. I would recommend wiring everything to match the schematic of the Sanguinololu, so that firmware changes would be minimal. You would have to reference the schematics of RAMPS as well.
The other option is to get a piece of proto-board and make your own RAMPS-type board. See: [reprap.org]

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