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What makes the MK3 so much faster?  

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jake.m3
(@jake-m3)
Eminent Member
What makes the MK3 so much faster?

200mm/s is very VERY fast, how is this possible?

Is it just hardware or software?

Maybe the new drivers? ❓

Posted : 02/12/2017 8:23 pm
rotarypower101
(@rotarypower101)
Estimable Member
Re: What makes the MK3 so much faster?

My assumption was a combination of the trinamic steppers and a rigid machine getting rid of those silly threaded rods?

Posted : 02/12/2017 8:30 pm
martin.m25
(@martin-m25)
Estimable Member
Re: What makes the MK3 so much faster?

Anyway MK2s was limited by extrusion capacity (around 11 mm^3/s) of the hotend which is unchanged on MK3, so I would expect only significantly faster non-print moves. Or am I missing something?
As U=L*dI/dt current slope in the motor windings doubles with twice the motor supply voltage (if motor inductance does not change), so max. step frequency also doubles. Acceleration does not if the motor current stays the same.

- Martin

- Martin

Posted : 02/12/2017 11:32 pm
Stitch
(@stitch)
Active Member
Re: What makes the MK3 so much faster?

The bondtech extruder probably helps 🙂

Posted : 03/12/2017 4:15 am
Shoey
(@shoey)
Estimable Member
Re: What makes the MK3 so much faster?

Wonder if skip detection plays a role in that... You can boost the speed with some confidence that it wont screw up your print over staying in a normal speed. Would be a nice write up to learn about everything that was done to boost the speed. Jo also said 24v allows them to run faster and cooler.

Posted : 03/12/2017 5:25 am
Peter
(@peter-12)
Estimable Member
Re: What makes the MK3 so much faster?

Did they only up the speed, or have they also changed acceleration?

Posted : 03/12/2017 9:16 am
RotaryDane
(@rotarydane)
Eminent Member
Re: What makes the MK3 so much faster?

There's a number of factors at play in my view.
1. The new y-axis frame design means that the axis itself is more rigid and allows for slightly higher y- acceleration and top speed.
2. The Trinamic steppers built in stall detection means that you can push the motors much closer to their skip-limit. Before you'd guess at a safe printing setup since you couldn't really know when a motor skipped a few steps, now If any one does the printer simply re-homes.
3. 24 volt setup. Since stepper motors are constant current devices double the voltage means double the work excerted by the motors. Meaning that the maintansble top speed is effectively doubled. Acceleration remains constant as it is dependant on current.
4. Bond tech extruder. Since the filament is now gripped from both sides grinding is effectively eliminated. Meaning that you can extrude at slightly higher rates closer to the hotends maximum flow-rate. The extruder-motor itself is a limiting factor here though, as it'll likely skip before hitting that max due to return-pressure in the melt chamber.

If you want to print faster there's a whole host of limitations. PR simply addressed some of them with the Mk3. From here it'll take some serious hardware upgrades to go higher. Realistically though, you wouldn't ever need or want to print any faster than 200mm/s imo.

Posted : 03/12/2017 10:24 am
ben.c5
(@ben-c5)
Eminent Member
Re: What makes the MK3 so much faster?


Realistically though, you wouldn't ever need or want to print any faster than 200mm/s imo.

I had a computer salesman in 1991 tell me that I would never in my life need more than a 1gb hard drive 😆

the rest of your post is knowledgeable and I appreciate you sharing it. that part made me chuckle

Posted : 04/12/2017 9:39 am
jweaver
(@jweaver)
Honorable Member
Re: What makes the MK3 so much faster?



Realistically though, you wouldn't ever need or want to print any faster than 200mm/s imo.

I had a computer salesman in 1991 tell me that I would never in my life need more than a 1gb hard drive 😆

the rest of your post is knowledgeable and I appreciate you sharing it. that part made me chuckle

🙂 When I bought my first PC, I paid a ton extra for a whopping 340M drive.. I was working on systems that used 5-20MB WInchester drives at the time and this seemed like black magic.

A while later, I was offered a chance to buy a 1GB drive which was so cutting edge at the time, it seemed imossible and I remember getting a lecture from my boss asking how I could ever fill such a thing.. he thought it the most pointless device in the history of time as no-one could EVER use such a thing...

I can't be too critical.. I am infamous for predicting that the "Internet" would never take off (After evaluating the www in the early 90s for the company I work for).. I later went on to say that SMS wouldn't be a thing.. And Digital Cameras would never replace film.. So I don't have a good track record in this area myself 🙂

Back to the subect, I never even consider that buying a Prusa would improve my print speeds.. I currently use a Printrbot which works perfectly well, but I had a look at my settings at the weekend and realise that I print and move at 50mm/s.. So the Prusa is going to work wonders here...

Posted : 04/12/2017 12:28 pm
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