How to achieve the best microstepping holding torque ?
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On the FFCP it's actually a bit of a design flaw.. what I found after my reading up on it was in good design the leadscrew should be driven at one end and the other end left floating - by floating one end of the leadscrew it can "wobble" for any runout without trying to push that side movement into the bed itself. flashforge tried to make things better by going to 10mm linear rods (good) and also holding the top of the Z leadscrew (bad) I pulled that top piece off and drilled it out slightly to allow the leadscrew to wobble at the top and it reduced the minor Z banding to almost nothing on my ffcp.
Taking the ball bearing that was holding the top of my lead screw appears to have completely eliminated any noticeable z wobble. With that I think I'm going to leave the current stepper and lead screw as is.
Thanks much for the tip,
Jeff
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Awesome, good to hear it was a fairly easy fix, and I agree the ffcp is actually quite a good printer, my mate still uses it almost daily and gets great prints out of it.
I mainly moved on as I wanted to do taller prints, and chose to go down the build my own delta route, but I still have fond memories of my ffcp.
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Awesome, good to hear it was a fairly easy fix, and I agree the ffcp is actually quite a good printer, my mate still uses it almost daily and gets great prints out of it.
I mainly moved on as I wanted to do taller prints, and chose to go down the build my own delta route, but I still have fond memories of my ffcp.
Thanks,
With all the mods I've done to mine so far it's really distancing itself from the original design. I can print faster and with much more accuracy then before and have a hotend that'll do 400C with the PT100's to match. Now to do something about these annoying LM8UU bearings.
Jeff
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I checked out your link, good stuff on all the changes.
One thing was bugging me today when I thought about it.. I didnt recall teh flashforge being that course on the leadscrew.
Your leadscrew should be 400steps/mm at 1/16 stepping. I was able to load up my config in simplfy3d from when I had the flashforge, and sure enough under the X3G firmware it was set to 400 steps/mm
1mm divided by 400 steps = 0.0025 per step with the standard ffcp leadscrew and 1/16 microstepping,
that makes more sense to me, since I recall I did a lot of printing at 0.25 layer height, which would be 100 complete microsteps.
my ffcp was the 1st release of the pro, but I cant imagine they changed the z leadscrew as ultimately it maintained compatibility with the makerbot replicator which had 400steps/mm on the Z
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I checked out your link, good stuff on all the changes.
Your leadscrew should be an 8mm, with 2mm pitch, that works out to 400steps/mm at 1/16 stepping. I was able to load up my config in simplfy3d from when I had the flashforge, and sure enough under the X3G firmware it was set to 400 steps/mm
1mm divided by 400 steps = 0.0025 per step with the standard ffcp leadscrew and 1/16 microstepping
Just checked the Prussa calculator. 8mm pitch gives you 400 steps/dev at 1/16 stepping which you are correct that is what the FFCP has. Still it's only 25 full steps which gives you 0.04 mm full step heights which is what you should use for multiples of your layer height.
Thanks,
Jeff
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Do not confuse pitch with lead. The pitch is the distance between threads - peak to peak if you like. The lead is the linear distance that a nut fitted to the screws would travel in one revolution. On a single start start screw, pitch and lead happen to be one and the same. On multi start screws, there are 2 or more threads offset by 360/the number of starts. i.e a 2 start screws has two threads offset at 180 degrees, a 4 start screw has 4 threads offset by 90 degrees. Multi start screws are simply a way of getting a very course thread (as is required for large or high speed linear movement for a small angular movement) but with the contact area between nut and screw of a fine thread. When calculating steps per mm, you should always use the lead (which may or may not be the same as the pitch depending on the number of starts).
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Thanks Deck, good information to know. It appears the FFCP is using an 8mm pitch single start lead screw. Removing the ball bearing they so intelligently placed at the top has eliminated any noticeable z-wobble which the printer had recently been suffering. The thread started out targeting how to achieve the best micro step holding torque per microstep. As it turns out at least in my case cooking the poor little motor appears to give the best results while running bed comp. I just need to replace it with a real motor.
I've also limited myself to 0.04mm increments on layers to try and stay close to the full step positions of the motor. The microstepping for now at least appears to be holding well enough to achieve good enough resolution for nice flat prints with bed comp. Ultimately it's not the bed on my printer that suffers so much as the 8mm rods which have been bowed from carrying around the MK10 extruders the printer came with.
Thanks,
Jeff
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@(In)Sanity:
…............ It appears the FFCP is using an 8mm pitch single start lead screw...............
I'm willing to bet £10 to a pinch of Chinese excrement that it isn't. Are saying that the distance between the peak of one thread and the peak of the next adjacent one is 8 mm? That would make it a cork screw, not a lead screw:)
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@(In)Sanity:
…............ It appears the FFCP is using an 8mm pitch single start lead screw...............
I'm willing to bet £10 to a pinch of Chinese excrement that it isn't. Are saying that the distance between the peak of one thread and the peak of the next adjacent one is 8 mm? That would make it a cork screw, not a lead screw:)
You are correct, it's 2mm pitch (just measured) with 8mm per rev and 400 steps per mm at 1/16 microstepping or 25 full steps per rev. In the end I only really care about the 25 full steps per mm. The Prussa calculator btw appears to have some perhaps poor labeling of terms as it shows "Leadscrew pitch" with the units being in mm per revolution. This is a bit misleading at best. I suppose technically still accurate.
Jeff
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@(In)Sanity:
…................... The Prussa calculator btw appears to have some perhaps poor labeling of terms as it shows "Leadscrew pitch" with the units being in mm per revolution. This is a bit misleading at best. I suppose technically still accurate.
Jeff
It's a common mistake that I often see . Pitch and lead get mis-quoted a lot and no, technically it isn't accurate.
