Re: Microstep July 04, 2014 03:48AM |
Registered: 10 years ago Posts: 378 |
Re: Microstep July 04, 2014 05:02AM |
Registered: 10 years ago Posts: 94 |
Re: Microstep July 04, 2014 05:27AM |
Registered: 10 years ago Posts: 14,672 |
Re: Microstep July 04, 2014 05:31AM |
Registered: 12 years ago Posts: 1,611 |
Re: Microstep July 04, 2014 06:32AM |
Registered: 13 years ago Posts: 7,616 |
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jstck
Microstepping [...] is not very good for "holding a position" as the motor won't be very strong at holding that microstep.
Generation 7 Electronics | Teacup Firmware | RepRap DIY |
Re: Microstep July 04, 2014 06:54AM |
Registered: 10 years ago Posts: 378 |
Re: Microstep July 04, 2014 09:15AM |
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Re: Microstep July 04, 2014 10:13AM |
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Re: Microstep July 04, 2014 11:44AM |
Registered: 10 years ago Posts: 14,672 |
Re: Microstep July 04, 2014 03:03PM |
Registered: 10 years ago Posts: 2,472 |
Re: Microstep July 04, 2014 03:16PM |
Registered: 10 years ago Posts: 14,672 |
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dmould
I've bought one of these [www.ebay.com] which is sitting on my desk. I plan on modifying my Ormerod to use it for the Z axis somewhen. I'll have to change the steps/mm and rotation direction.
Re: Microstep July 05, 2014 04:40AM |
Registered: 10 years ago Posts: 378 |
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dc42
1. Backlash in the gears. Not a problem now, but was a problem earlier when the gears didn't fit very well.
2. The Z nut trap wearing, so that the Z nut can rotate within it by a significant amount. I had to re-print the z-nut trap recently. This could possibly be improved by using a tapered hexagonal recess in the Z-nut trap.
Re: Microstep July 05, 2014 04:40AM |
Registered: 10 years ago Posts: 378 |
Re: Microstep July 05, 2014 03:32PM |
Registered: 10 years ago Posts: 378 |
Re: Microstep July 07, 2014 07:00AM |
Registered: 10 years ago Posts: 2,472 |
Quote
dc42
Quote
dmould
I've bought one of these [www.ebay.com] which is sitting on my desk. I plan on modifying my Ormerod to use it for the Z axis somewhen. I'll have to change the steps/mm and rotation direction.
That looks good! What's the thread pitch? If you have DaveK's aluminium X-plate and rib, then it should be easier to fit, because his x-rib already has a cutout for an extended z-motor shaft.
I've noticed a couple of problems with the standard Z axis drive:
1. Backlash in the gears. Not a problem now, but was a problem earlier when the gears didn't fit very well.
2. The Z nut trap wearing, so that the Z nut can rotate within it by a significant amount. I had to re-print the z-nut trap recently. This could possibly be improved by using a tapered hexagonal recess in the Z-nut trap.
Re: Microstep April 15, 2016 05:25PM |
Registered: 8 years ago Posts: 776 |
Quote
droftarts
Hi Joar
Yes, the Duet uses 16x microstepping as standard. You can change the microstepping, but the chip we use (Allegro A4982 [www.allegromicro.com] ) only has full-, half-, quarter-, and sixteenth-step modes. These are set using the MS1 and MS2 pads on the Duet; put a solder bridge between the pairs of pads to change the microstepping.
Ian
RepRapPro tech support
Re: Microstep April 15, 2016 06:01PM |
Registered: 10 years ago Posts: 14,672 |
Re: Microstep April 16, 2016 11:23AM |
Registered: 8 years ago Posts: 776 |
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dc42
Reducing microstepping DOES NOT increase motor torque. The torque per microstep does indeed reduce as you increase microstepping, but the torque per unit of angular error does not change. So reducing microstepping will not solve your problem.
The only reason to reduce microstepping is if you need such high speeds that the electronics can't generate the steps fast enough. The Duet can generate more than 100K steps/second per motor, so that isn't likely to be an issue. I invite you to do the sums to check. In the unlikely event that you do need very high speeds, you can cut the trace on the PCB as already explained. It just isn't worth implentng software controllable microstepping on boards with x16 microstepping and 32-bit processors, because it is so rarely needed.
It sounds to me that you have either a poor extruder design, a very weak motor, motor current set too low, or a motor designed for much higher currents than the Duet can provide.
Re: Microstep April 16, 2016 06:12PM |
Registered: 10 years ago Posts: 14,672 |
Re: Microstep April 17, 2016 04:39AM |
Registered: 8 years ago Posts: 776 |
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dc42
The Duet can generate more than 100K steps/second per motor
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dc42
Using 1.7mm filament and a 0.4mm nozzle, the maximum extrusion rate you need during printing is about 5mm/sec. If you multiply that by the extruder steps/mm then that will give you the corresponding step pulse frequency.
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Of course, higher speeds are useful when loading filament, and when doing retraction.
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What is the steps/mm of the Flex3drive if you use 16x microstepping? If you divide that into 100K then that will give an estimate of the maximum filament speed available without reducing microstepping.
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Also, what is the rated current of your 60Ncm motor?
Re: Microstep April 17, 2016 07:55AM |
Registered: 10 years ago Posts: 14,672 |