mastory

The Z motion mihht likely be a parabola relative to the bridge length...

I have wondered if it would be beneficial on bottom bridge layers to lower Z slightly in the first 1/2 -2/3 of the bridge span while stringing across, then in the last portion return to the normal layer height. The purpose would be to fight the natural sagging that occurs while the line is still flexible, then connect it to the support at the other side. Also, I have seen where when printing adjacent bridge lines ( especially bottom bridge layer) where the nozzle dissturbs the previous line and breaks it, sticking to the nozzle. Lifting slightly in mid bridge would defeat that I think.

You might be experiencing a difference in the infill due to the slicer. As I recall, a few slicer versions ago, infill behavior changed to be more sparse. I don't remember if was grid or line infill that began to act differently causing much more sparse behavior. Possibly try a different infill style depending on what you are currently using.

No experience with Ninjaflex. Assuming the printer is printing OK with more standard filaments, I would alter settings that would promote easier material flow. Maybe a bit hotter yet, or taller layers. Flexible materials are not really considered reliable for bowden printing, so I wouldn't get my hopes too high regarding the expected results.

Happens when you have very strong adhesion. Happens to me on window glass with hairspray, PLA or ABS. Usually can be avoided by waiting for the print to cool and pop off. Not uncommon or entirely avoidable. This is why I print on cheap replaceable window glass ~ $4/ea cut to dimensions I specify. Have several so always a clean spare ready to go.

read this thread: https://community.ultimaker.com/topic/21659-calibrate-extruder-with-cura-15/?tab=comments#comment-201643

I think maybe not enough cooling. Fan is working? Have the other successful prints had a larger X-Y area, thereby allowing more cooling prior to subsequent layers? Maybe try a combination of slower print time, increasing minimum layer time, and maybe enable Lift Head? I sometimes print 2 or more small area parts to provide more cooling time and pick the best one when its done.

I print many parts that start in SW2012 and newer. There are quality settings when the model is exported as an STL that can affect the quality. Maybe try turning up the resolution in the output settings. I have never had an issue with missing surfaces coming out of SW

+1 Its hard to argue with George. I think he's right again. You could use the new extruder unmounted to print out a mounting bracket -or- don't mount it. It's probably best mounted IMO. What will work for your set up?

Thanks for the tips. Have considered printing roof, stopping at Z and applying tape, but never tried it. I did find there is a setting for "support interface line width', which is meant to be above a roof I think. This is essentially what I was getting at before. I gave it a try. There are some errors on the code relevent to that line width and its association with interface and roof; which options enable it and what it controls. The intent is there, but I think with some tangled associations in the code. I think it could be very powerful if sorted out. I'll do a bit more testing and post another thread on the specifics. I ended up splitting the part horizontally and placing the glue joints against the build surface. Matt

Thanks as always @GR5, I did find the horizontal expansion setting. Also I've upgraded to 3.2.1. I'm setting up to use my single extruder UMO. Below is an example of the sort of parts I am often asked to print. It s prototype part nest for automation. It needs to be accurate when finished. At first glance, you might think the best would be to split the model and glue. I have done that often on past parts. I would like to print as one piece instead of splitting and fabricating, so I can reduce hand finishing time, and remove the painstaking glue operation and chance for error. A longer print time is in my opinion cheaper than my manual labor. This part is 45x65x105mm. I'm considering a custom support model such as the red item below. I would like to figure out how I can print these two parts with different parameters defined for each body. I would like to separately control the red body to be printed at a high line density, but under-extruded and only a few layers thick on top of a support roof. Sparse auto generated support would be used beneath the red item. I went thru all the support options in 3.2.1, and have sort of achieved the above with a support roof, tapered support, etc. I think I'm pretty happy with it overall, but I like to be able to under-extrude the support roof, or at least the very top of it. This could be termed as separately controlling the roof line width. I have not printed yet, just parsed all the slice settings and sliced. I'll start the print tonight. It looks like about a 5 hour print.

First I need to say I'm not on the latest realease. I think 3.0.2. Not sure, I'm at work atm, and machine is at home. I print some rectangular parts often that have large horizontal overhangs. I have been splitting my models when possible and fabricating after print. I'd like to print as one piece with support and save fabrication time at the cost of print time. I'd like to be able to define the support interface to be severly underextruded, but with a dense line spacing to give a nice bottom surface, but easily break away. Is there a way to do this? Is the support interface underextruded by default? If so, by what degree? Can I define it? I havent tried the support interface yet. I'd like the support to extend laterally a couple mm from the model so the bottom outside model perimeter is fully supported. Is there a setting for this? Couldn't find one. I see in the version I have, the tool tips are missing recommendations that used to be there, with much more generic and in my opinion lacking decriptions of the various slicing functions. I hope there are plans to renew the old tips that were helpful. Thanks

UMO & UMO+ are very repairable. A good share of the mechanical components are generic commercial items that are readily available. The entire machine is available in 3D models an drawings - so you can make your own. The electronics and programming are fully open. Anything is pretty much available if you look around. You might be better off replacing/upgrading the extrude feeder, and hot end, but there again lots of options and the electronics and firmware are well documented to be adapted as needed. People here can help when it gets technical. All the answers are available if you have the drive to research a bit. I think these machines will be in operation for a very long time. There are no secrets about the design, and no one has a corner on the market for parts or ideas.

Your firmware version may be noted somewhere in your graphic interface or somewhere in the menu or on boot up. Search it up. What does your manufacturers info say?

I've run pronterface on my win7 and winxp. Go here https://github.com/kliment/Printrun/releases/tag/printrun-1.6.0

Yes, I was quite tired when I wrote above G500. Corrected. Save parameters is indeed M500. For a whole list of gcode commands look here.

@dryphi wants to calibrate his extruder feed constant. Pronterface (also known as Printrun) is a free and open source program that lets you control (all?) arduino based printers via USB. It has a very friendly user interface for manually controlling printers, and a command line printer interface. It also allows sending Gcode files to print. You could slice a part in Cura (or other slicer) and send the Gcode file to the printer via Printrun. It also has some great graph widgets for watching your temperatures etc. IMO it is a very nice, lightweight, powerful and clean program. Some older versions of Cura had a similar printer control interface. I don't know which ones. The GUI in Printrun can do some of what you want, and the command line interface could be used to issue the commands I mentioned above. Typed at the command line: G91: set coordinates to Relative G0 E100; tells your printer to extrude 100mm M92 Exxx.xx; redefines your extrusion constant where xxx.xx is the new scale factor You could search M92 and your printer brand and model and get a starting point. By trial and error you can issue the above commands until you have you extrusion constant precise. Then add M500; to save the value

I've used Pronterface to do this in the past. The on screen controls can be used or the command line. An M92 Exxx code will redefine the extrusion constant which can be delivered via the command line in Pronterface if you want to change it. I think M500 on the command line would then save the change. I see testing and resetting the extrusion constant as an essential maintenance and calibration procedure that anyone might need periodically. This is especially important to off brand or homemade printers or secondary market extruders.

I'm also interested in swapping, because I'd like to do a mark2 or zerog upgrade. I think the necessar firmware changes are not so friendly with UMO pcb. I knew about the different temp sensors and number of extruder drives. Are the motors in UMO, the same as UM2? I may be better off building another printer....

Unfortunately, mic6 is only available in 1/4" and greater thicknesses. I dont know that thickker would hurt, just more money and maybe platform sag. I would use any common 6061 alloy. Pretty much any alloy will work even steel. Save some trouble and buy this item off Ebay or Amazon. In steel, you might fold the edges for stiffness. MIC6 on the other hand is great for a heated bed for its flatness, although because of the minimum thickness, causes a bigger heat load. I used it for my bed plate. For those who dont know, it is a cast and ground material, thus a high flatness and thickness tolerance (and smooth).

Are your sure the end of the shaft doesn't have a small burr preventing assembly? That shaft OD does seem a bit on the high side for normal bearing use. Normally though, quality bearings are on-size, so even a slightly undersized shaft should go in. 8mm ID's are very difficult to measure, and if your bearings are from a reputable source, your interference may be smaller than you think. If the bearings are only going on the ends, try polishing the shafts locally with sand paper. It won't take much polishing, and best if spun by a machine. You might get them to go together just by freezing the shafts, but will be difficult to re-position or disassemble later. Never press the inner race onto an shaft by applying force to the outer race.

I don't believe you will achieve much better size accuracy than that. Many of my parts are prototypes for pieces that will be milled from steel. Trying to replicate the accuracy of milled pieces pushes the limits IMO. To help, I often print several trial pieces, adjust my scaling independently in X,Y and Z attempting to compensate for uneven shrinkage - while keeping other variables controlled as much as possible. Sometimes, I edit (scale) the individual features of the model independently. Uneven shrinkage is hard to predict. It can differ due to uneven cooling, part shapes of varying section thickness, infill interaction with the shell... When I have a position or size that must be held, I print slightly large in that area and bring it to size with secondary operations; sanding, filing, milling, drilling. For rectangular pieces, one of my favorite tools is a piece of polished marble tile with a sheet of 220 sand paper on top.

you install a stand alone copy of Pronterface

+1

I had a similar problem with my UMO. Not sure if the UM2 card reader socket is the same, but UMO socket has a small micro switch built in to recognized if a card is in or not. I would check out this switch if it exists on your machine. In my case, it wasn't a faulty switch, but a poorly placed chip/crack in the side of my SD card where the switch touches it. A new card was the remedy for me. Your's sounds like it might be the switch since you have multiple SD cards. Otherwise, I would check that the contacts are clean. I am now very careful how I insert the cards.