Posts made by Simspeed

Very nice setup Ian…I plan to use a similar overhead gantry for the extruders on my machine. The length of drag line cables on yours confirms what I thought would be about right for mine.... Keep posting, I enjoy your blog too.

How much Z movement is the slider assembly experiencing Ian? Also, how is the Metrol switch working out?

@dc42:

If the gantry is sufficiently flexible (as any large enough gantry is sure to be), then you could extend the technique I suggested to 4 independent motors.

Ok, good to know…thanks. I'm thinking I will want to home the Z carriage at the top of travel on power up or power loss to prevent crashing into anything on the print bed. Then follow your instructions to probe the bed and 4 corners to level the carriage before beginning a print. Sorry if this is basic stuff to most of you but this will be the first attempt at initializing a printer build for me. Thanks.

In the case of my large H-bot, I have a fixed bed with the XYZ carriage suspended on 8mm lead screws at 4 corner posts. I originally planned to use a belt drive for multiple screws but adapting 4 motors to the 4 screws is a much simpler overall design given the ability to sync all four motors at power up as DC42 described a while back. In a 4 motor example where the Z carriage is relatively level to begin with, leveling two adjacent corners at each narrow end of the carriage rectangle, and then leveling the carriage end to end along the long dimension seems to me as the simplest case. Will that be practically doable?

I'm interested to see how that metrol switch works out for you Ian. I took your dove tail idea and incorporated it into my hotend mount. I downloaded the CAD file for the switch and added it to my file. I like your idea for the E3D Cyclops mount. Small compact to give me maximum XY travel.

5, 4, 9, 7, 13 My four new Z motors arrived so I'll soon be ready to implement #5.

Please keep in mind the 4 motor Z axis upgrade DC….thanks.

Hi Ian….I had a similar idea for the hot end mount for my machine. I added an adjustment screw to fine tune the tip offset from the bed. I just used a U shape slot to slide the hotend mount into with threaded brass inserts for the screws.

I ordered the Y splitter component from this site some weeks ago but it hasn't arrived yet. I'm interested to see how it will work.

https://www.aliexpress.com/store/product/3D-printer-E3DV6-Cyclops-dualhead-upgrade-kit-2WAY-in-1WAY-out-TL-Feeder-Prusa-bowden-splitter/1654223_32770576556.html?spm=2114.8147860.0.0.XP0QMV

Thanks Ian…I think I understand the concept. So at the advanced tool change, the current color filament is retracted and the new color filament begins to push to the nozzle end, all the while continuing to eject the old color until it if fully expelled at the desired point in the print. Your calculations of the volumetric characteristics of your hot end of choice determines how far in advance the tool change is positioned in the gcode ahead of the slicer generated position. How are you effecting replacement of the gcode tool changes? Manually or through a programming script of some kind? If code, how do you apply that to the slicer generated file? Thanks...Terry.

Hi Ian…thanks for the hard work and contributions. If I understand the process correctly, you are taking the slicer G-code and inserting your tool change routines at points that correspond to where color changes are expected. Having not yet worked with slicers or G-code I'm unaware of the coding sequences that you describe using Python scripts. Am I missing the entire point of how this works...? Thanks...Terry.

@Dougal1957:

@simspeed do you have a link to that Chinese PEI Supplier please?Doug

Hi Doug….here is the link. Address your comments to Cun Zhang and mention me (Terry Peterson) if you don't mind. They quoted me $106 for a 560mm X 773 x 3mm sheet of PEI 1000. I am revising the size to 803mm long for repricing so I'm sure it will be a little more. I plan to place my order when the repricing hits my inbox. Best of luck...

https://gz-ideal.en.alibaba.com/product/60489979785-213203887/Transparent_Ultem_PEI_Sheet_25mm.html?spm=a2700.7803228.1998738836.186.EXHxWd

I posted an earlier reply to you comment Bot….just disappeared?? I said I appreciated hearing from someone like you with a positive experience with the thicker PEI sheet. That's encouraging...I think I'll go ahead and take a chance on a sheet for my build. Thanks....TP.

I had thought to use a combination of adhesive and fasteners on the thicker sheet. I imagined the extra thickness would improve durability and flatness given the larger surface area of my bed. I had not given proper consideration to the insulator effect, do you think it would act more so than say a 6mm piece of glass? The price quote I got for a 560 x 803 x 3mm sheet of PEI was less than any of the print surface supplier here are charging for their thinner material….given equal size that none of them offer. Thanks...

Given my understanding of the upcoming firmware revision for multi-motor Z axis machines, the power up cycle would initiate Z homing for all motors in order to sync the Z motors to a common starting step position. I assume Z home would be at the top stop location. I'm new to this so please indulge my ignorance. Thanks…

I got a good price for 3mm PEI sheet from a Chinese distributor. I haven't ordered it yet because I read that material thickness is hard to keep flat using adhesives. I originally though to mount it to the tool plate with stainless flat head screws but now I'm unsure, I'm afraid that method will produce bulging around the screw heads . Has anyone used a thick sheet of PEI? Thanks…

Given the weight of a large bed with a 6mm tool plate, I am assuming its location will be fixed. My build is similarly large with a bed consisting of a 6mm tool plate hard mounted to 8020 extrusions and a PEI top layer. Total weight is roughly 37 lbs. Instead of building a leveling mechanism for the bed, I decided to hard mount it square and level to the frame and then use 4 point leveling of the XY carriage using the corner lead screws with independent motor control for each. I'm relying on the upcoming firmware revision dc42 is planning for the DuetWifi to control and sync a 4 motor Z axis. I have yet to learn what type of probe will work best for that application but I'm guessing there are a number that will. I have a BL Touch mount I want to use for mapping bed flatness, I assume it can perform the carriage leveling operation as well. Best of luck with your design Calvin….

I noticed where PEI filament is available. Someone who has the capability of high heat printing in an enclosed cabinet, could print custom size and thickness PEI bed covers using the technique deckingman is showing. Likely not affordable when compared to commercial PEI sheets from China.

@dc42:

I would be concerned about that too. You could mount the leadscrews on thrust bearings, then it would be convenient to use 1:2 gearing to drive them from the motors. Or revert to using belt drive. Or perhaps it is possible to find a thrust bearing/leadscrew combo that lets the leadscrew shaft protrude below the bearing, then you could use a flexible coupler to connect it to the stepper motor.

Thanks dc42….see my comments above concerning support of the Z screws. I am looking forward to your finished work on the 4 Z motor firmware. Thanks to you and all the DuetWifi team.

@deckingman:

I see that you have the motors under the screws and it looks like the motors will be taking the full weight of the bed? Difficult to tell from the pics. If so, then my concern is that steppers don't generally have thrust bearings and aren't usually designed with the spindles to be loaded in that manner. If you have some sort of thrust bearing under the screws or if the motors you plan on using have thrust bearings (which is unusual) then it's not an issue.
Ian

Thanks for your comments Ian. The bottom plate for each C-Beam upright has a bearing pocket that supports the shaft assembly. The shaft itself has a locking collar that bears the weight of the assembly (XY carriage proportionally) on the bearing housing. The bearings are not radial thrust bearings; just std. shaft bearing Openbuilds offers. The motor shafts and bearings bear no weight so we're comfortable with that part of the design. The top of the shafts are free floating inside the top plate which has an oversize hole surrounding the shaft penetration. If the OB bearings prove to be a problem I'll have to replace them with some form of thrust or tapered bearing to support the XY carriage weight.

I believe I am really going to like the flexibility of independent motors for the four Z screws when dc42 finalizes firmware to control them. It is an added cost, but in my application being able to level the carriage to the fixed bed is more desirable than the alternative. I don't like to spend unnecessarily, because like most of us my resources are limited, but at the beginning of the project (its gone through several iterations now), I decided the design would take precedence using least expensive components where available. For example the OB acme lead screws over more expensive ball screws, and nylon wheels over linear guides. I did splurged on C-beam extrusions but they offer a much more rigid structure and enclosed routing of the drive components. The polycarbonate enclosure is another expense but I believe the long term benefits outweigh the costs.

I am experimenting with a less expensive linear guide approach. I test printed nylon guide supports for the Z and Y axis that are encouraging. I ordered IGUS Tribo filament to test in comparison to the nylon sliders and OB wheels. That should be arriving any day now, so I'm excited to see what the outcome of those test will be.

BTW….I very much enjoyed your blog presentations on multi-color printing. Show us some more on your current printer when you get the chance. Thanks...Terry