When I first heard Velleman would be offering a new z-axis threaded rod, I though I would want one. It seems to be offered in conjunction with the new K8200 1.75 mm extruder. The 1.75 mm extruder seems to be coincident with the release of the new K8400 dual extruder printer.
I decided to “pass” on the new treaded rod and opted instead for a trapezoidal spindle. Velleman recommends that the threaded rod be upgraded when changing to the 1.75mm extruder.
I have two questions which I think are very valid:
Why is a 1.75mm filament superior to a 3mm filament? Thinner layers are not automatically possible with the K8200 just because you decrease the nozzle diameter. I personally have never been able to print complex objects reliably in the 0.2 - 0.25 mm layer range. Will my problem not be even worse with thinner layers?
How can a new threaded rod solve a problem caused by a different threaded rod? A trapezoidal spindle is precision machined, whereas a treaded rod is not.
There are two other things to consider in changing the extruder and rod.
Firmware changes will be required if the pitch of the rod is different, and for extruder steps. If it is not different, then what reason is there to believe the change is worthwhile?
All the carefully tweaked slicer parameters that we have all arrived at will not work with a new extruder and a different rod.
I have no doubt that a K8200 can benefit from a better z-axis spindle and a better extruder. But I am not willing to risk my money on the K8200 upgrades that are coincident with the introduction of the K8400 Vertex printer. I believe that moving to two 1.75 mm extruders will only serve to double the problems that all 3D printers have. Personally, I would not trade my K8200 as an even swap for the new printer. However, I would trade it in an instant for a single extruder model made by Cube or Makerbot.
It is no mystery to me why Velleman has dropped the price on the K8200.
This month (Nov 2014) Make Magazine will publish their review of the top ten 3D printers. I won’t be holding my breath to see where the Velleman printers rank!
A smaller nozzle diameter may allow narrower extrusion width. But I don’t believe the resolution of the K8200 is determined by the extrusion width. If the nozzle cannot be accurately positioned in the X, Y, and Z directions, then layer width is not the determining factor in resolution. Neither is layer height.
I would rather have a .5mm diameter nozzle with accurate positioning than a .3 diameter nozzle with sloppy positioning in X, Y, and Z.
!.75mm filament now accounts for around 70% of sales according to the filament suppliers I’ve spoken too. It requires less extruder pressure and more extruder steps per mm which helps with the direct drive extruders.
The K8200 already uses 600 steps/mm for the direct drive extruder. Contrast this to the x and Y axes which use 62.5 steps/mm. The z-axis uses 2560 steps/mm and its problems are legendary because the poorly machined threaded rod determines the actual positioning accurcy.
Whatever the virtues of 1.75mm filament, converting a K8200 to use 1.75mm filament is like putting lipstick on a pig.
I believe it to be a waste of money because filament size pales beside the more serious problems of the K8200. The K8200 can certainly benefit from a better extruder and a better z-axis, but I’m waiting to see what the experience of others is with this questionable upgrade.
I’m more likely to buy a better printer than to sink more money into the K8200.
If you are getting good quality prints with 3mm filament, then changing to 1.75mm filament would accomplish nothing except to increase print times.
I have settled on 0.3mm layers as a satisfactory compromise (for me) between quality and print time. I have a low tolerance for any prints that take longer than a few hours. I cannot imagine printing something overnight, but that is just my personal preference.
There is no difference in print times with the same layer thickness. Most people who want to change from 3mm to 1.75mm are planning to use a smaller layer thickness.
A typical nozzle size for 3 mm filament is 0.5mm. A typical nozzle size for 1.75mm is 0.35mm.
None. I have done a lot of research thought, in books, magazines, and cyberspace. In particular, the November issue of Make magazine reports on several printers.