6Ohm Steppers vs 1.25Ohm 2.5A
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All the supplier would say was that:
The new ones are better
same specs of Pruda
Prusa
I can't see an easy listing of what the Prusa motors are, they also appear to be laser marked to the Prusa branding.
Running 3 P3Steel with Duet 2. Duet 3 on the shelf looking for a suitable machine. One first generation Duet in a Logo/Turtle style robot!
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@doctrucker said in 6Ohm Steppers vs 1.25Ohm 2.5A:
I can't see an easy listing of what the Prusa motors are, they also appear to be laser marked to the Prusa branding.
I have not found anything about them either when I was searching a while ago.
But then again: just using the same motors as Prusa without matching the mainboard does not make much sense. The MK3 does not run on 24V because they just found a cradle of 24V PSUs somewhere in the back of the warehouse...
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@doctrucker said in 6Ohm Steppers vs 1.25Ohm 2.5A:
All the supplier would say was that:
The new ones are better
same specs of Pruda
Prusa
I can't see an easy listing of what the Prusa motors are, they also appear to be laser marked to the Prusa branding.
Does the machine use 24V power? If so then lower current/higher inductance motors should be OK, and they may also make stall detection easier.
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Just had another 'conversation' with them and they may now be releasing the specs for the motor, but not refunding me for the unbranded Arduino I just cooked due to the limit switch wiring not being clear enough in their Spanish documentation that covered an alternative board rather than mine!
In addition the firmware had thermal runaway protection was disabled, and used 1.0.2, rather than the latest 1.1.9-bugfix.
The look into the RAMPs system has certainly been useful (now running again on my spare proper Arduino!) and it'll be interesting to have the two archetectures running in parrallel to really see some of the benefits the more recent boards have realised.
@dc42 Just 12V on this system. I think to go higher with the Arduino/RAMPs you need to supply the 5V separately to avoid cooking the 5V regulator.
Very tempted to make this my first YouTube product review!
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@doctrucker said in 6Ohm Steppers vs 1.25Ohm 2.5A:
@dc42 Just 12V on this system. I think to go higher with the Arduino/RAMPs you need to supply the 5V separately to avoid cooking the 5V regulator.
That's correct. Even with a 12V supply, if a graphical LCD is included in the system then the 5V regulator on the Arduino is likely to overheat anyway. RAMPS was an OK solution when it came out, but now that most users have LCDs attached and 24V power is popular, it's well past its use-by date IMO.
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
@dc42 I agree with you there. The performance of the current systems are far superior.
My rational here was I wanted to learn a little about the Marlin firmware as I had a potential contract with a local education centre who were planning to use the Ender-3 systems as a teaching aid which the students then get to keep. After reading into the systems a little more I realised that there was a whole heap of minor tweaks that may need to be done to make them build as originally intended (e.g. better quality bowden couplers etc) but also some critical safety mods to the firmware that were needed to enable Thermal Runaway protection.
So I could have bought the ender 3 which was likely to need a lot of fettling/fiddling (like my Ormerods & Mendel) or try out a P3Steel based system which I had hoped would give me a reliable (if not a little slow) work horse. I started to look into ordering the parts myself but saw this kit with all the bits to get going.
As it happens the contract approval looks like it is going to fail in the finance department, despite the project funding being on a use-it-or-lose-it basis and the project owner being very keen to proceed. The up side is I have a nice solid printer available, but equally the downside is of course I'll have to fund it.
A definite positive is that I have much better idea for what I want to replace the Mendel frame with, and this years xmas present consists of various bits that are required to do that.
I'm seriously contemplating pricing up what I could pull together a Maestro based bundle of parts for based on the P3Steel, but I have heard so many people say the margins are tight and I'm not sure what I can bring to the table that they didn't.
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A snippet from this morning's chat to enjoy:
09:19 [supplier name clipped]
Stepper motors don't depend voltage
09:21 Me
Wrong.
Higher voltage allows the peak current to be reached quicker (as it is fighting against the inductance - which you won't state) which allows the peak torque to be sustained at a higher RPM.
09:22 [supplier name clipped]
I will send you the specs of our motors/Prusa motors
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So they've changed the motor specs to be similar to the ones Prusa uses without changing to 24V power at the same time? Crazy.
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Yeah, I still can't find anything definitive on the Prusa motors. Following the other comments here I mentioned the 24V for prusa thing and they said:
09:18 Me
You changed motors from what was advertised and said it's what prusa use. Prusa use 24V and a different control card so how is that releavent to my machine?
09:18 [supplier name clipped]Thank you for the feedback
09:18 [supplier name clipped]The last firmware is available for [product name clipped]
09:19 [supplier name clipped]Yes Prusa is the same motors for 12V board ( MK2S)
09:19 [supplier name clipped]and 24v board (MK3)
Call me pessimistic but I panicked a bit when I saw 2.5A rated motors swapped out for motors that are set with a 450mAh current limit. I get that the 2.5A motors may never have been run at 2.5A and de-rated and the higher resistance motors may be able to get to full current quicker as it was so much lower. If this was a great performance swap you'd think they'd just be up front about it rather than take so much verbal beating to release the spec. I've a gut feeling cost is the key driver here.
All that said I'm not willing to name and shame just yet as I've not all the information and I also have a gut feeling this is a one-man-band with a very fancy website who has clearly over stretched himself. I've sympathy for that and if I do review it I will do my best to find positives to balance the negatives a little!
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Looking forward to doing a review on this printer. Latest issue (after shelving it over yuletide) came to light this morning after finally soldering the 14AWG wire to the MK3 Alu heat bed. Measured resistance and I see 0.7 ohm. That's neatly about 200W and I see no shorts to the aluminium. I make that 17A through a 11A poly fuse. That along with disabled firmware thermal protection is boarding on a real liability for them. Checked against a spare MK3 board and it has a much higher resistance and thinner tracks.
