Please help me to pick the right electronics package.

I've been looking at 3d filament printers. The ones that are commercially available just can't do what I want to do. The build areas are too small. Some have very tall Z axis, but this isn't a priority for me. It's not the build volume that is important. I simply want more movement in either X or Y. Also, for the cost of a new printer, I can build one with better linear components.

I have some left over linear components from a CNC build. I have been working on a design for my own 3d printer. The only question is whether I will buy a small printer to 3D print some of the parts for it, or make it all out of metal. Belt drives for the X and Y and two screws driving a fairly large Z plate.

I will need help on the electronics side. For example, I understand that the arduino mega and ramps 1.4 can only drive up to 6 motors, is that correct? Also people have been saying that this combination limits the speed of their printers because it can't keep up?

Here's what I want to do........

Dual motors driving the Y axis, I also want to have two limit switches on one side for a homing sequence on startup to make sure the gantry is always square. I want two motors because I prefer to keep the design simple, I'd like to use Nema 17's all around, and because my gantry will weigh a bit more than the average 3D printer, so the extra torque is good. I realize there are other design options out there, but right now I'd like to pursue this one.

One motor driving the X axis.

Two motors driving the Z axis, I also want to have two limit switches on one side for a homing sequence on startup so I keep my build plate level.

Two extruders (actually have been thinking of perhaps even 3). I've been looking at E3D hotends and bowden extruders. I'd like to have the capability to go up to 300 deg C as a maximum.

So that's 5 motors driving the motion, and 2 to 3 for the extruders, with the ability for two axis to have homing to two independent switches each.

I'm also planning on a Z axis proximity sensor / switch and a heated bed

What kind of electronics hardware do I need to do this?



Is there a different shield available for the arduino mega that can accomodate more motor drivers?

I've been looking here for answers:

[reprap.org]

I'm not really sure what options are good ones. Can anyone offer some advice, or a review on something they have tried? I'm good with the mechanical side, but the electronics, not so much.

Thank You in advance for any info!

So you want 7 or 8 independently-driven motors. One option for you is Duet WiFi or Duet Ethernet, plus DueX5 expansion board. That combination provides 10 stepper drivers with the possibility of 2 more external drivers. With 10 drivers you could handle a 5-input Diamond hot end.

Instead of using 2 separate Z endstop switches, you can use a Z probe to measure how far out of level the bed is and adjust the two motors independently. If 3 Z motors are used, you can level the bed in both directions this way.

If you are looking for dual extrusion, I suggest you look at IDEX architectures - two independent X carriages. This avoids the problem of the non-printing nozzle interfering with the print. It needs an extra motor to handle the second X carriage.

Have you considered using a CoreXY architecture?

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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

Radds + extension board gives you 8 or 9 separate drivers. you need to use an Arduino Due with it.

---

P3steel DXL, with Due/RADDS/Raps128 dual Wade's extruder

Quote
dc42
So you want 7 or 8 independently-driven motors. One option for you is Duet WiFi or Duet Ethernet, plus DueX5 expansion board. That combination provides 10 stepper drivers with the possibility of 2 more external drivers.

I'd definitely choose an Ethernet connection over Wifi.

I've watched a couple videos about this controller just now, thank you for the suggestion, wow, seems very capable. This is definitely a premium solution.

Price wise, it's way higher than the arduino mega and ramps 1.4, that many use, I can see why, but it's perhaps too premium for me. 130 Euros for the Duet Ethernet, plus 82.50 for the Duex 5, looks like a daughter board isn't necessary if you have the Duex 5? Plus it looks like I'd need about 30 Euros minimum for sensors? What's VAT, 20%? + Shipping, 242.5 x 1.2 = 291 plus let's say 9 for shipping, that's 300 Euros assuming I don't get hit with customs fees. That's $454 Canadian and it doesn't include motors, wires or proximity sensors, or the bed heating electronics, or the power supply.

LOL. I can buy an arduino Mega and ramps 1.4 for $40 Canadian shipped from EBay. Of course, I don't think that can do what I need.

It's a really great suggestion, and I appreciate it, but are there any less expensive options? I can't blow this much of my budget on just the control boards.

Quote
dc42
With 10 drivers you could handle a 5-input Diamond hot end.

I watched a review of a multiple colour hot end where the block make by changing colours weighed more than the printed part. My main reason why I want two print heads is that I want to print dissolvable support material. I want to make some high quality prints with complicated shapes for a specific application. I figured if I went for two, why not three, but really, I only need the 2.

Quote
dc42
Instead of using 2 separate Z endstop switches, you can use a Z probe to measure how far out of level the bed is and adjust the two motors independently. If 3 Z motors are used, you can level the bed in both directions this way.

OK, that's good to know. So the Z proximity sensor can do this. This is configured in the control software? For example, if using Duet, this is where you would set this up?

Quote
dc42
If you are looking for dual extrusion, I suggest you look at IDEX architectures - two independent X carriages. This avoids the problem of the non-printing nozzle interfering with the print. It needs an extra motor to handle the second X carriage.

This is interesting advice. Thank You. Funny enough, I was just looking at the bnc3d machines on Youtube before I read this. I assume they have a homing switch on each side of the gantry for each print head on initial power up? Also looks like they have a build in calibration program. After I read your comment I had another look, and did find a DIY vid on YouTube of this very thing, so it is possible, what kind of hardware software support is required to do the calibration? I'm seriously considering this now.

Quote
dc42
Have you considered using a CoreXY architecture?

I have thought about it. I have also thought about having a moving table in the short axis (not Z). If I go with the IDEX architecture I'll have to rethink a few things about the design. I haven't ruled anything out for certain at this point. I don't need a big working area in both X and Y, so that makes the moving table possible. A rectangle, not a square, is what I'm going for.

I haven't ruled anything out. I do want to keep it as simple as possible. The coreXY seems overly complex to me, I see all those belts and pulleys and think oh, my, what is going on there.

I also haven't ruled out connecting both Y pulleys via a shaft to a single motor.

I really appreciate the input. What I'd like to find out at this point is if there are any more affordable options for the boards to drive the extra motors, and what specifically I need for an IDEX architecture solution. It seems like it might end up being a bit more complex than first imagined.

Quote
Don McLean

......................
Dual motors driving the Y axis, I also want to have two limit switches on one side for a homing sequence on startup to make sure the gantry is always square. I want two motors because I prefer to keep the design simple, I'd like to use Nema 17's all around, and because my gantry will weigh a bit more than the average 3D printer, so the extra torque is good. I realize there are other design options out there, but right now I'd like to pursue this one.

That bit caught my eye. Something very similar came up on the Duet forums and DC42 demonstrated in principle how it could be done by creating additional but hidden axes. I wanted to take it a step further with my Dual CoreXY printer. That is to say that I wanted to home each CoreXY mechanism independently but then drive them in sync as if they were a single CoreXY for printing. The problem was that additional axes are normally created using Cartesian Kinematics. I posted on the Duet forums and less than 30 minutes later, DC replied that what was needed was a completely new CoreXYUV kinematics. About two and half hours later, the firmware was implemented! A couple of days or so to fit the additional switches and sort the wiring out and I was up and running.

So in my view, apart from the fact the the Duet board is a fantastic piece of kit and will do everything you want, that kind of support is well worth an extra few bucks. If you are interested, here is a little write up I did on this 5 axis homing [somei3deas.wordpress.com] and here is a video of it in action [www.youtube.com].

---

[somei3deas.wordpress.com]
[www.youtube.com]

On the 8 bit side, a few boards support 6 steppers and with a stepper expander 7. This meets your motor requirements and 8 bit boards do fine with cartesian kinematics.

Quote
Don McLean
LOL. I can buy an arduino Mega and ramps 1.4 for $40 Canadian shipped from EBay. Of course, I don't think that can do what I need.

It's a really great suggestion, and I appreciate it, but are there any less expensive options? I can't blow this much of my budget on just the control boards.

You get what you pay for. I think you will be spending a lot on mechanical parts, bed, motors etc. for that machine and IMO it doesn't then make sense to compromise it by using budget electronics. But I am of course biased - see my signature. If you decide that 7 drivers are enough, you could use a DueX2 instead if a DueX5. VAT is not applied to orders delivered outside the EU. You can also order Duets from Filastruder in the US. The Duets also provide an awesome web interface with high speed file upload to the SD card, high current stepper drivers with up to 256x microstepping to keep your motors quiet, easy firmware configuration using a text file on the SD card (which you can edit in the web interface), save/resume print after loss of power, etc.

Quote
Don McLean
My main reason why I want two print heads is that I want to print dissolvable support material. I want to make some high quality prints with complicated shapes for a specific application. I figured if I went for two, why not three, but really, I only need the 2.

In that case I would definitely suggest IDEX.

Quote
Don McLean

Quote
dc42
Instead of using 2 separate Z endstop switches, you can use a Z probe to measure how far out of level the bed is and adjust the two motors independently. If 3 Z motors are used, you can level the bed in both directions this way.

OK, that's good to know. So the Z proximity sensor can do this. This is configured in the control software? For example, if using Duet, this is where you would set this up?

See [duet3d.com] for how to do it on a Duet/RepRapFirmware.

Quote
Don McLean

Quote
dc42
If you are looking for dual extrusion, I suggest you look at IDEX architectures - two independent X carriages. This avoids the problem of the non-printing nozzle interfering with the print. It needs an extra motor to handle the second X carriage.

This is interesting advice. Thank You. Funny enough, I was just looking at the bnc3d machines on Youtube before I read this. I assume they have a homing switch on each side of the gantry for each print head on initial power up? Also looks like they have a build in calibration program. After I read your comment I had another look, and did find a DIY vid on YouTube of this very thing, so it is possible, what kind of hardware software support is required to do the calibration? I'm seriously considering this now.

Hardware: 2 (or more) X carriages running on the same linear rail or rods, each driven by a separate motor and belt, each with its own homing switch (typically one at each end)

Software: any firmware that supports IDEX (or ITEX if you have 3 carriages instead of 2).

HTH David

Edited 1 time(s). Last edit at 12/15/2017 09:55AM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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

That sounds like an unnecessary amount of motors in general.

Using CoreXY you only need two stationary motors to handle XY movement, the opposing nature of the forces applied via the belt drive helps with mechanical accuracy.

CoreXY seems confusing but is very simple in actuality. It's basically the same way movement is handled in an Etch-a-Sketch.

While auto bed leveling with 3 z motors does have some appeal, if you build/calibrate the printer properly it shouldn't require constant re-leveling. With several popular firmwares offering mesh bed mapping/compensation I'd say that is another drop in the bucket for taking a simpler approach.

Then again, there's no engineering like over-engineering

Edited 1 time(s). Last edit at 12/15/2017 11:23AM by obelisk79.

I don't think the etch a sketch uses coreXY, I've looked into the mechanism myself recently. Etch a sketch looks to have have been around longer than coreXY. More importantly, the X and Y are decoupled and independent, unlike coreXY (one knob moves X, one knob moves Y).

I stand corrected. Still, the mechanism is similar and relatively simple once you've messed around with it in person.

the etch a sketch is more similar to an ultimaker, it's just an ultimaker uses the outside rods as drive shafts to avoid some belt routing.
EDIT: Anyways, back onto the topic. CoreXY+several extruders may be trouble for 8 bit controllers, not sure. Depending on how large the printer is, and how heavily built it ends up, you might need dual y axis drive with nema17s.

Edited 1 time(s). Last edit at 12/16/2017 01:54AM by Trakyan.

Not that my opinion matters at all but I have to also recommend the Duet. I'm a recent purchaser from Filastruder and still finishing my build however I believe things have gone smoothly in general because of the Duet. What I notice from your build requirements is that you want a high end machine but want to take a chance on cheap electronics, seems kind of counter intuitive if you ask me.

LOL. I can buy an arduino Mega and ramps 1.4 for $40 Canadian shipped from EBay. Of course, I don't think that can do what I need.

Since this won't work for your application you certainly can't use it as a comparison. I get your point though... I don't know about your past experiences with cheap Chinese electronics but they are just that...

One thing to keep in mind when comparison pricing anything is the amount of your time it will cost to fix or track down problems when you make bad buying decisions, there's a cost to that no matter how much free time you think you have.

Aside from the board itself being a beautiful piece of work, it just works.

The Duet support is also impressive, very knowledgeable as well as the designer/engineer of the product.

ampapa,

Cheap electronics doesn't necessarily mean poor quality.

There's some merit in considering "Good Enough for the job" rather than "Good for EVERYTHING I might never need, just because."

DuetWifi is absolutely a quality product, but it's a luxury expense imho when you can do just (or nearly) as well with something that costs 75+% less.

Choose what you feel will work best for you. Perhaps you should look into RAMPs (or one of it's derivatives) with an expander and use a firmware like Teacup or Klipper, they will likely perform beyond the mechanical limitations of your printer in most circumstances.

Edited 1 time(s). Last edit at 12/16/2017 09:52AM by obelisk79.

Thanks to everyone who has responded so far and for all the suggestions!

It's taken me a while to research some things, but I still don't know what I'm going to do, so it's still a work in progress and I still need help.

I was looking at the duet a bit closer. Yes, I found the Canadian distributor, it's $400 Cad + tax for the bare bones parts. It looks like it uses the trinamic drivers. www.trinamic.com I found this quite interesting, particularly in their talk of S curve acceleration. Do you guys use this on your machines? It's a pet peeve of mine that this isn't available in mach 3 which I use for CNC.

Here's a quote from their website:

"The TMC5130 allowed us to eliminate the failure-prone mechanical endstops and the noise generated by stepper motors. The result is a cleaner and less intrusive product that will change the way 3D printers are perceived in the future.“

So does that mean that the trinamic drivers can accommodate hard stop homing without the need for switches? There are other systems that can do this, for example, the clearpath servos don't require limit switches for homing

OK, I just did a bit of searching on the duet forums:

[www.duet3d.com]

Can I use the trinamic drivers with a radds board?

I still don't know what solution I will use. I think 32 bit is a no brainer, but I haven't decided on which one. Also, 24V or higher is a no brainer.

I've been looking more closely at dual driven independent heads like on the bnc3d sigma printer. This takes up alot of space. Is it really worth it?

Also I've been looking more closely at the H-bot and Core XY designs. Mechanically it wouldn't be a problem to add a second belt driven head to this design but given the nature of the H-bot and Core XY architectures, could the software handle an extra independently driven head in combination with either of these designs?

So I'm working out my mechanical design at the moment,

Have you ever come across an 80T + 20T combined idler pulley? Or a 60T + 20T combined idler pulley?

Running a 20T GT2 pulley from the stepper to a 60T idler that is connected to a 20T gear turning the drive belt would give me a gear reduction of 3:1, which if I run the steppers at a good voltage could give me better native resolution and better / smoother performance.

Alternatively I've been looking at 16T gears, but the idlers only have a shaft of 3mm, and that seems too small for my liking.

It looks like most people are simply running 20T gears without any reduction for their pulley systems?

Thanks again for your help everyone, it is appreciated!

Yes, trinamic drivers like the TMC2130 and the ones used on the duet (I forget the exact model) do support hard stop homing without limit switches, but they do not turn the stepper into a servo. I also don't know if the firmware supports it, I've read a few forum posts that summarize to "lower the motor current and ram the axis into the frame for a while and you'll probably be at your home position" rather than saying that the missed step detection for homing is available in firmware. Yes you can use trinamic drivers with the RADDS. I don't see why 32 bit is a no brainer, especially for a cartesian machine, in fact I think the BCN sigma uses 8 bit? 32 bit boards are a bit overhyped in a lot of use cases. But yes, 24V is a good idea on a large format printer.

As for the dual independent print heads taking up a lot of space, they shouldn't take up much more space than any other dual extruder set up. As you start looking at larger and larger printers, the extra 50-100mm you'll need on the X axis gets less and less significant compared to the build volume.

Any reason you need a combined idler pulley? Why not just mount two next to each other? Ask yourself if you need the gear reduction to begin with, most other designs do fine without it. I don't think you'll see the benefits of the higher resolution because of a number of things like extrusion width etc.

Quote
Don McLean
...
Also I've been looking more closely at the H-bot and Core XY designs. Mechanically it wouldn't be a problem to add a second belt driven head to this design but given the nature of the H-bot and Core XY architectures, could the software handle an extra independently driven head in combination with either of these designs?

RepRapFirmware supports it, it's called CoreXYU. It uses 2 extra motors instead of just one. There is a thread about it in the CoreXY section of these forums.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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

Quote
ampapa
Not that my opinion matters

Your opinion certainly DOES matter. Thank You for posting in my thread.

dc42, really impressive machine you made, also I'm very impressed by the dual level homing from the duet.

amigob, thank you for the suggestion, I'm seriously considering it.

Quote
Trakyan
As for the dual independent print heads taking up a lot of space, they shouldn't take up much more space than any other dual extruder set up. As you start looking at larger and larger printers, the extra 50-100mm you'll need on the X axis gets less and less significant compared to the build volume.

I'm going to be using high quality size 25 linear rails. The typical bearing block for these is 4" long. So let's look at a 20" long rail, if you want to be able to print support under the full print area, and assuming each print nozzle is centered on each bearing you are looking at 6" on each side being unusable (in reality it's more as you need a bit of extra space so the bearing blocks don't collide). 20-12 = 8, the amount is significant.

So I just bought a couple 80mm long blocks for the gantry, so a bit shorter, and I have a 21.5" rail, so that leaves 12" movement maximum, subtract a bit so thing's don't collide, 1/4" between the blocks at each side and at each end, about 11" movement with two independent nozzles vs about 18" with only one for that rail length, so yes, again, it is significant.

11" is all I need, and if one side was "parked" that would give me 14.5 to 15" movement. That's fine. No complaints there.

Quote
Trakyan
Any reason you need a combined idler pulley?

It's much easier to build something with an idler pulley than to mess around with pillow blocks, custom designs, etc, especially if the pulley is oriented vertically. Still not certain if I should buy a small 3d printer to make some parts for this, although I can probably do everything from aluminum on my mill.

All advice and input is gratefully appreciated! Thank you everyone so far for your contributions.


At the current moment I am drawing up my design, there are still a number of things not set in stone.

What does everyone think about 6mm gt2 belts?

What kind of limit switches should I use? Do actual mechanical switches work better for homing (vs. prox sensors)? Any Suggestions?

6mm GT2 belts are good, the problem I found when I wanted to use them on my SCARA printer was that there is not much choice of 6mm GT2 pulleys available.

Mechanical endstop switches are entirely adequate in my experience.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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

Fair enough, so the dual carriages take up a significant portion in your case. I was just saying as the print volume gets bigger, the lost area lost gets less significant.
to
As for the idlers, you'll need a shaft to mount your combined idler anyway wont you? I don't see why it's any more complicated to mount two separate idlers next to each other on the shaft.

Quote
Don McLean

dc42, really impressive machine you made, also I'm very impressed by the dual level homing from the duet.

Just as a point of order, David didn't post a link to his machine so I guess you meant mine which is the dual CoreXY (see sig). I'm not easily offended though I just wanted to point it out because I'm just an end user of the Duet board and not affiliated in any way.

---

[somei3deas.wordpress.com]
[www.youtube.com]

Size 25 rail mixed with Nema17 motors and 6mm belts don't seem like an appropriate combination. Linear motion components should be of similar performance because in a general sense you will be limited by the weakest link (including pulley/idler mounts, and belt tension).

You should drop down two rail sizes or raise the rigidity of the other linear motion components. Its more of an aesthetic criticism, but IMO its silly to put 6mm belts in a machine that might weigh 60-100lb.

Apologies, deckingman, I blame the holidays for making my brain frazzled. I actually did spend quite a bit of time on your website. Thanks for the info . I was wondering where all the build logs were for people who made their own printers? I'm wondering if I should do a design log here?

Trakyan, idlers typically have a bearing in them, or bushing, or something to help them spin. So no, I could just bolt them in place, perhaps with the help of a few spacers. At least that is my understanding. They are not the same thing.

69117.....Do you think 11mm belts are more appropriate? But not appropriate for a Nema 17? I disagree that the size 25 blocks are a bad choice......I am only going to use one per connection, so each entire carriage is one block, of course I believe this will give better motion than three or four of the small round bearings or 4 V groove wheels on a carriage, which physically are larger than a single size 25 block (even though they probably weigh less). I agree that I could drop down two sizes and it would be fine. They are more than what is necessary but I have some available. They are expensive, even the smaller sizes! So better to use what I have. I should probably have a look at the torque of the Nema 17's and do some math.

I should also mention that I am considering a fixed gantry, either with a cantilevered short axis (I'm making a rectangle printer, not a square one) and moving bed in the Z, or like the makergear machines like the one in this review

[www.youtube.com]

But much larger, and with two Z axis, one on each side.

Does anyone know if I can add a single servo control to any of the previously mentioned options? I'm not talking about a servo motor to spin a belt, I'm talking about a single servo the kind you might find in a radio controlled airplane, normally used to move a rudder or elevator or aileron on a RC plane?

Quote
Don McLean
Trakyan, idlers typically have a bearing in them, or bushing, or something to help them spin. So no, I could just bolt them in place, perhaps with the help of a few spacers. At least that is my understanding. They are not the same thing.

Sorry, my bad (wrong terminology/poor explanation). Not an idler pulley, just regular old pulley with a set screw. You'll be mounting your pulleys on some sort of shaft (I'm assuming?), so why not mount two pulleys next to each other and put the shaft on a set of bearings. Look at the way the pulleys are set up in the image below.
[maxdesign1990.files.wordpress.com]
In the bottom right, there is a pulley that drives the belt that moves the axis, and a pulley with a belt going to the motor. The two pulleys don't have to be machined from the same block of aluminium, just mounted to the same shaft to achieve the same effect. A few extra parts involved but it allows for more freedom and flexibility with pulley ratios.

Quote
Don McLean
Does anyone know if I can add a single servo control to any of the previously mentioned options? I'm not talking about a servo motor to spin a belt, I'm talking about a single servo the kind you might find in a radio controlled airplane, normally used to move a rudder or elevator or aileron on a RC plane?

I don't know about other boards but you can connect servos to the Duet. You can use pins on the expansion connector or if you buy an expansion board (which also give you additional stepper drives and a host of other connectors) there are dedicated servos connectors. See here [www.duet3d.com]. There is also a gcode command to set the servo position [www.duet3d.com]
HTH

---

[somei3deas.wordpress.com]
[www.youtube.com]

Is RAMBo electronics still good? It comes with 8 stepper drivers as standard and can run Marlin. Josef Prusa is using a newer mini version on all his printers. I have RADDS running RepRap FW and an Azteeg X5 running smoothie but Marlin still seems to be the most well developed and updated firmware that I use. The RADDS controller seems to almost be orphaned and I heard that the Smoothieware guy is out of action for a while.

If you don't mind using 8 bit electronics, RAMBo is still a solid bet. Although at that price point I'd just go the extra distance for a 32 bit board.

KDog, I'm biased, but IMHO you've got too rosy view of Marlin. Its support for pressure advance came 3 years after at least 2 other firmwares had it. It was also late supporting mixing extruders. Its support for delta printers was poor for quite some time. It has never made the break from the constraints of performance and RAM of atmega2560 processors, so you won't find it supporting the types of feature that need more performance and RAM. Its configuration mechanism (editing source code, recompiling and re-uploading the firmware) is prehistoric.

RepRapFirmware has advanced rapidly, because it has a developer (me) working on it almost full time, aided by chrishamm and others in the community. I've just released a new version with more than 70 new and improved features, even though the previous version wasn't lacking anything significant for 3D printer control. The maturity and reliability of RRF are amply demonstrated by the fact that several manufacturers of large commercial 3D printers have adopted it. Of course, you are losing one of the major benefits of RRF - the web interface - because your RADDS doesn't provide a network port.

Unless/until the Marlin devs create a permanent fork for 32-bit processors and put serious effort into catching up with existing 32-bit only firmwares, Marlin is bound to lag behind. That's not to say that it isn't suitable for controlling i3 style and many other uncomplicated 3D printers, of course it is - until you have experienced something better, then you won't want to go back.

PS - I agree with the previous post, RAMBO is IMO the best 8-bit board around. The Einsy board used in the Prusa i3 MK3 is a derivative of RAMBO.

Edited 2 time(s). Last edit at 12/24/2017 02:43PM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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

Quote
Trakyan

Quote
Don McLean
Trakyan, idlers typically have a bearing in them, or bushing, or something to help them spin. So no, I could just bolt them in place, perhaps with the help of a few spacers. At least that is my understanding. They are not the same thing.

Sorry, my bad (wrong terminology/poor explanation). Not an idler pulley, just regular old pulley with a set screw. You'll be mounting your pulleys on some sort of shaft (I'm assuming?), so why not mount two pulleys next to each other and put the shaft on a set of bearings. Look at the way the pulleys are set up in the image below.
[maxdesign1990.files.wordpress.com]
In the bottom right, there is a pulley that drives the belt that moves the axis, and a pulley with a belt going to the motor. The two pulleys don't have to be machined from the same block of aluminium, just mounted to the same shaft to achieve the same effect. A few extra parts involved but it allows for more freedom and flexibility with pulley ratios.

Yes, I was looking at that design, thank you for posting the diagram, it explains it well. The problem there is that I plan on using square rails.....so that won't work for me, although I could still join the two long axis with a shaft.....and haven't decided if I'm going to do that or not.

Also I still haven't decided on whether or not to have two independent extruders on separate blocks. The only thing I have decided on is that the bed will move in the Z axis.

I currently leaning towards having an E3D type design Cyclops and Chimera, either mounted side by side or on separate blocks. Up to 3 feeds being used at a time, the extra would just be there for a backup.

I won an EBay auction for some NSK size 15 blocks and rails yesterday. So it looks like I will have just over 16" of Z movement using 4 blocks and 4 rails, I will most likely also be using two 1605 ballscrews for the Z axis. I'm sure size 12 ballscrews would also work, but they aren't as common and the 1605 stuff is inexpensive on EBay.

So typically the motor drivers are 2 Amps if you use the ones that plug into the boards (as opposed to an external driver)? So when you are trying to pick the largest torque 2 Amp motor do you typically use Nema 17 or Nema 23, because I noticed that there are several 2 A Nema 23 on EBay that are quite inexpensive.

Quote
deckingman

Quote
Don McLean
Does anyone know if I can add a single servo control to any of the previously mentioned options? I'm not talking about a servo motor to spin a belt, I'm talking about a single servo the kind you might find in a radio controlled airplane, normally used to move a rudder or elevator or aileron on a RC plane?

I don't know about other boards but you can connect servos to the Duet. You can use pins on the expansion connector or if you buy an expansion board (which also give you additional stepper drives and a host of other connectors) there are dedicated servos connectors. See here [www.duet3d.com]. There is also a gcode command to set the servo position [www.duet3d.com]
HTH

deckingman, thank you for the response! Next question, does anyone know how to make a good wire cutter using a servo? I've seen some thrown together things on YouTube, mostly involving a pair of scissors with the servo closing the handle, but there has to be a better way.

dc42, looks like I came to the right place to ask questions. I did not know that you were a firmware developer.