My CoreXY Build Plan January 29, 2016 01:31PM |
Registered: 9 years ago Posts: 49 |
Re: My CoreXY Build Plan January 29, 2016 03:50PM |
Registered: 11 years ago Posts: 14,686 |
Re: My CoreXY Build Plan January 29, 2016 04:24PM |
Registered: 9 years ago Posts: 49 |
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dc42
It sounds to me that you are planning to spend a lot on the mechanics of your printer, but spoiling it by choosing poor electronics. Arduino/RAMPS is fast enough to drive a CoreXY printer, but has too many limitations to make it a good choice on anything other than a bargain basement printer. In particular it is not 24V capable. You should be using either 24V or mains power for a heated bed of that size.
I won't comment on the mechanics because that is not my area of expertise.
Re: My CoreXY Build Plan January 29, 2016 06:35PM |
Registered: 12 years ago Posts: 5,797 |
Re: My CoreXY Build Plan January 30, 2016 02:31AM |
Registered: 10 years ago Posts: 83 |
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the_digital_dentist
Go for a 32 bit board like Duet or Smoothieboard.
I use the latter. It was a refreshing change to convert my printer from Arduino/RAMPS to Smoothie- configuration changes on smoothieboard are simply edits to a single text file that is read by the board each time it boots up. No more hunting through multiple config files and a screwing around with the flakey Arduino IDE to recompile firmware every time you make a change. It has numerous other features that make it superior to the A/R setup. More info here: [smoothieware.org]
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jnsbanman
Ok... What would make a good match electronics wise for a printer of this size? I am wide open to suggestion.
I have looked at some of the Azteeg products and they look good. I would not need more then 2 extruders, and 3 axis motors. The X3 looks like it might fit the bill.
Or the GT2560 look interesting but could not find too much about it... Looks pretty new.
Re: My CoreXY Build Plan January 31, 2016 01:15PM |
Registered: 9 years ago Posts: 49 |
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grat
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the_digital_dentist
Go for a 32 bit board like Duet or Smoothieboard.
I use the latter. It was a refreshing change to convert my printer from Arduino/RAMPS to Smoothie- configuration changes on smoothieboard are simply edits to a single text file that is read by the board each time it boots up. No more hunting through multiple config files and a screwing around with the flakey Arduino IDE to recompile firmware every time you make a change. It has numerous other features that make it superior to the A/R setup. More info here: [smoothieware.org]
People are still recompiling their firmware for a config change? I thought even Marlin had moved way past that within the last couple years-- Repetier hasn't needed recompiling for config changes since I've been using it.
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jnsbanman
Ok... What would make a good match electronics wise for a printer of this size? I am wide open to suggestion.
I have looked at some of the Azteeg products and they look good. I would not need more then 2 extruders, and 3 axis motors. The X3 looks like it might fit the bill.
Or the GT2560 look interesting but could not find too much about it... Looks pretty new.
The three main contenders for 32 bit are smoothieboard / azteeg, running smoothieware, duet running dc42's version of the reprapfirmware, or due/radds running Repetier/due (dc42's RRF is in theory now usable on due/radds as well).
All three are now available in the US as well, which is a nice change, and they all three support 24V power supplies.
Also consider the newer THB6128 stepper drivers-- finding a motor that plays nice with the DRV8825 is more difficult (Having said that, the smoothieboard and the duet have non-socketed drivers, which is either good, or bad, depending on your point of view. The azteeg X5 v2 is also soldered in, but they're THB6128's).
Having said all that, your design looks very much like an ultimaker gantry, instead of coreXY-- not that there's anything wrong with that per se, but I don't know how well it scales.
Re: My CoreXY Build Plan January 31, 2016 05:11PM |
Registered: 11 years ago Posts: 14,686 |
Re: My CoreXY Build Plan February 01, 2016 08:37AM |
Registered: 9 years ago Posts: 49 |
Re: My CoreXY Build Plan February 01, 2016 10:08AM |
Registered: 10 years ago Posts: 101 |
Re: My CoreXY Build Plan February 01, 2016 10:39AM |
Registered: 12 years ago Posts: 5,797 |
Re: My CoreXY Build Plan February 02, 2016 08:49AM |
Registered: 9 years ago Posts: 49 |
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the_digital_dentist
There are two main reasons why socketed drivers are less reliable than those mounted on the controller board.
1) heat- the driver chips are designed to be heat sinked by bonding them to a ground plane on the circuit board. The socketed drivers don't have that and even if they did, the board is so small it would not be a very effective heat sink. The drivers mounted on the smoothieboard are soldered to the ground plane and it sucks the heat right out of them.
2) trim pots to set the current- the pots are fragile and located very close to other nodes in the circuit. It is very easy to break the pot and very easy to short out connections on the driver module when trying to adjust motor current. It is also sort of difficult to know exactly what the motor current is when tweaking the pot because the different versions of the modules use different reference resistors and you need to measure the voltage across that resistor as you adjust the pot. That leads to setting the current too high and burning up the driver chip (see #1 above). It's a tight fit to get the screwdriver on the pot and get a voltmeter on the board to try to read the reference voltage. On the Smoothieboard (and probably Duet), motor current is set using digital pots that are adjusted by a variable in the config.txt file. You specify the current you want and that's the current you get - no guessing, no measuring, no pots, no voltmeters.
As a dentist, I am used to working in very small space that is dark, wet, has a moving tongue, sometimes accompanied by a strong gag reflex, and often only able to see what I'm doing in a mirror, so I would generally be regarded as having "mad hand skillz". Back when I was using a RAMPS board in my printer I went through about 5 of the motor driver modules because of broken pots, shorted connections, and toasted chips. Believe me when I say that the socketed modules are a poor design, period. If you go with a board that has socketed motor driver modules, buy a bunch of extras because you're going to need them.
Re: My CoreXY Build Plan February 02, 2016 11:08AM |
Registered: 12 years ago Posts: 5,797 |
Re: My CoreXY Build Plan February 02, 2016 05:01PM |
Registered: 9 years ago Posts: 24 |
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the_digital_dentist
For the X axis (on which the extruder carriage rides), I would also use a single linear guide instead of a pair of round rails. It will be lower mass, more compact, and the bearings are as near perfect as you can get. The rails are rectangular, typically wider than they are tall when the bearing block rides on the top surface, so if you have a rail that is 12 x 8 mm, turn it so the 12mm side is vertical to minimize flex, or mount the thing on an aluminum tube to increase rigidity.
Re: My CoreXY Build Plan February 03, 2016 12:32AM |
Registered: 12 years ago Posts: 5,797 |
Re: My CoreXY Build Plan February 03, 2016 09:03AM |
Registered: 9 years ago Posts: 49 |