calinb
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Posts posted by calinb
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You should really talk to printrbot people. Not this forum.
Or get an Ultimaker!
Seriously, this is one of the best forums, I believe, and the open source availability and usability (UM has really improved it, of late) is a very compelling selling feature of the Ultimaker. Though any 3D printer comes with a road full of bumps, I have never regretted buying an Ultimaker almost three years ago.
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Plus it doesn't off gas gnarly chemicals like arsenic n stuff while printing. that trimmer nylon is nasty stuff.
Have you found more than hearsay that it's "nasty stuff" at the temperatures we print? I'm talking about empirical testing!
I'm not saying that it isn't nasty, but how convenient that a reasonably priced and excellent performing source of nylon would be deemed inappropriate and unsafe to use by those who sell printer filament!
As with many activities, I recommend playing it safe by not printing where one breathes (that goes for any plastic--even PLA). Ink jet printers have been found to out-gas unhealthy fumes in an Australian study and they are found in all office buildings and many homes too!
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I mostly print nylon with my UMO. I've printed Oregon brand Gatorline trimmer line, Taulman 618, and 3ntr PA6. The only one I can't get to work well is 3ntr, because the layer to layer bonds are too weak and part strength suffers (even at nozzle temps as high as 275 C at only 25 mm/sec.) I like to print the others at about 260 C for maximum layer bonding strength, typically using 0.100 layers and nice and slow 25 mm/sec speed. Even printing infill at 40 mm/sec results in a weaker part and my motivation for using nylon in the first place is high part strength (and occasionally its lubricity and chemical and solvent resistance).
The only build surface material that I've found that is satisfactory for large parts is machineable Garolite--and you will have to machine it (or sand it forever on a flat glass plate) to get it really flat, which I highly recommend. Shrinkage and bed adhesion challenges make printing ABS seem like child's play, in comparison to nylon. A bed that's +/- 0.002" (or about +/- a phonebook page of paper) in flatness still deviates more than a 0.100 mm layer height and really isn't flat enough! For good results, 0.001" in level/flatness or better is necessary.
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Ha -- "trigger warning"?
That's a nice trick. That said, it's not the shape I would have expected; it is a pre-1964?
Sadly, no. It is for a recent model that has a cheap plastic stock and a blind magazine. It enables the use of one of the better stocks that are inlet for two-piece bottom metal, like the Hogue overmolded stock made for FNH or the Coyote Outback laminated wood stock. The blind magazine box is retained along with the original trigger guard. The printed part covers the hole where the two piece bottom metal door and frame usually rests.
I have a 243 WSSM and the stiff Hogue works much better with a sling than the original stock. It's actually the most accurate rifle I own. The rifle shoots under 1/2 MOA out to 400 yards+ (the longest range I've tested) with my best handloads. Who says chrome lined barrels can't shoot! ;)Winchester put chrome lined barrels on all the WSSMs, because they were worried they would be barrel burners. I remember Winchester graphs of their testing showing that a non-chrome lined WSSM barrel that lasted for 2000 rounds would last for 4000 rounds with chrome lining. Of course they didn't specify what constituted a worn out barrel.
I've since used this trick on another arm--a slingshot!
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Ha -- "trigger warning"?
That's a nice trick. That said, it's not the shape I would have expected; it is a pre-1964?
Sadly, no. It is for a recent model that has a cheap plastic stock and a blind magazine. It enables the use of one of the better stocks that are inlet for two-piece bottom metal, like the Hogue overmolded stock made for FNH or the Coyote Outback laminated wood stock. The blind magazine box is retained along with the original trigger guard. The printed part covers the hole where the two piece bottom metal door and frame usually rests.
I have a 243 WSSM and the stiff Hogue works much better with a sling than the original stock. It's actually the most accurate rifle I own. The rifle shoots under 1/2 MOA out to 400 yards+ (the longest range I've tested) with my best handloads. Who says chrome lined barrels can't shoot! ;)Winchester put chrome lined barrels on all the WSSMs, because they were worried they would be barrel burners. I remember Winchester graphs of their testing showing that a non-chrome lined WSSM barrel that lasted for 2000 rounds would last for 4000 rounds with chrome lining. Of course they didn't specify what constituted a worn out barrel.
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I recently stumbled upon a work around for my z-stutter problem, other than power cycling. It's not any more convenient than cycling the power in most cases but if I use my Ulticontroller to move the the stage down and then up a few 1/10s of a mm (MUST use the 0.10mm selection, because the 1mm movement selection will actually cause stuttering on the next home), then the stuttering never occurs.
This workaround can be done before starting a new print after a print has completed (stuttering never occurs on the first print after power-on) or after manipulating the stage using the 1mm selection, which always causes stuttering. The last manipulation of the stage must be in the UP direction using the 0.1 granularity selection from the UC menu.
Again, this is evidence that that my UMO has always had a strange electrical/Marlin/interaction/bug (from the day I built it and first plugged it in) and I'll probably never get to the bottom of the problem. It's really been a nuisance, however!
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gr5 is right; it's probably a loose connection somewhere on the print head. Fluctuations in readings are the first warning, typically. I've had to correct loose connections several time overs the 2-1/2+ years I've had a UMO. I found that the black strain relief clip only increases the frequency of the wires breaking near the clip inside the insulation (where the broken wire is not visible). Having a large free loop in the white connector wires to the tie point well up the Bowden tube reduces the problem to a very low frequency of occurrence. I found a large supply of the crimp-on pins for the white connector housings and they should NOT be soldered to the wires (the factory soldered them on my UMO). The ridged solder creates a stress point right at the pin. Crimp connectors on multi strand wire are the way to go! Most recently, a TC wire loosened right at the green PCB connector.
I've had numerous electrical problems with my UMO (really the only problems after initially sorting our the initial build bugs) and I still have one gremlin that I'll probably never successfully debug. I spent a great deal of time debugging and reworking my Ulticontroller board. It was so unreliable until I manage to correct all the problems from a sloppy assembly, I soldered-in a socket for my LCD display so I could remove the LCD assembly from the base board easily.
Hopefully the new and more expensive electronics in the newer models is of higher quality that what shipped with my UMO.
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Thank you for your prompt reply and the link, Sander.
I recently came across one of Joergen's posts that had migrated to this new forum. However, the link he provided to my howto on printing nylon no longer worked.
I would provide it to you, but I can't even find Joergen's post. (Global-only searches suck and I can't find an "advanced search" button.)
I would also like to suggest, if you still want to, to post further feedback in this thread.
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This is the second time since I purchased my UM and started to contribute to the UM forum that UM has changed the design of their forum. After the first time it happened, I could not find my posts and photos (and presumably others had the same problem). I made a big mistake by continuing to expend effort to contribute here. My contributions required many hours of my time to produce. This time, it's the same again, except this latest forum design is a hugely worse design than either of the last two forums. It sacrifices function (like powerful advanced search capabilities) for what some misguided manager or web dev thinks looks nice. Also, once again I cannot find my posts.
I'm done here. I'm moving all of my 3D printing forum contribution efforts to the reprap forum. It's plain looking but stable, unchanging and much more useful than this mistake of a forum! To play it safe, I'm using GrabCAD to share my models too. Well--I was doing that already. At most, I'll post a link here in the UM forums.
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I pretty much came to the same setup. I bonded my thin Garolite sheet to a 1/4" thick sheet of precision Mic6 aluminum plate using contact cement. Then, to get it really flat, I machined it. It can be re-machined, as necessary, to freshen the build surface when it gets too potmarked and chipped under tough to remove sections of parts.
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Just an idea, ofc I have not tried it yet. What if you create the man-made-supports with a 'second extruder' and you set that extruder to less flow, or smaller nozzle? Then you edit the gcode to rename the extruder 2 usage to extruder 1, then the area that it's supported should have less material, even understrusion maybe? This way they should be weaker? Maybe with the proper running they might even be easier to break apart.. umm I think I must try this
Edit: I think you can choose the supports to be done by a second extruder, then that extruder should have it's own specifications. Then the rest should be just a search&replace
I think your idea would realize an improvement to some extent, Neotko, but a second extruder is a lot of extra hardware, complexity, and cost to accomplish something that can be completely solved in software.
If you select LINES support then the support consists of just straight lines, or walls with a thickness of 1 line.
I am using LINES already. Look at the gcode with a gcode viewer (perhaps the one in Cura but I use Replicator-Host). Line are not really lines; they are doubled lines (loops).
In the new Cura, there will be a third option, called zigzag, which is somewhere in between the two.
If the zigzags are not loops, this would help.
Or are you talking about custom designed support meshes?
I must often resort to custom support (or the old netfabb slicer, which will can provide support as thin or thinner than I'd ever use).
: Your idea still results in double lines, which is just the thing calinb is trying to avoid.
Yes--but the lines would be thinner doubled lines. :)/:( However, I have no plans to install a second extruder system.
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It would be nice to be able to make very thin support lines (not loops). Is there any way to do this in Cura? Even when set to 1%, I spend too much time cutting and sanding support away from nylon prints with a Dremel tool.
Alternatively, I spend too much time designing support into my solid models, and even then, I run into the problem that Cura makes only looped paths. Accordingly, placing the very smallest pillars that Cura will "see" and "sample" into the model works best for nylon, in my experience.
If Cura could extrude the thinnest possible single support line, it would be very helpful.
Thanks,
-Cal
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I've tried a few belt tensioners on my UMO over the last 2-1/2 years. I always come back to simple modified (bent) clothespin springs. I'd like to have a set of the newfangled official UM springs, because they have a nice and deep square shaped hook on them so they should stay put on the belts very well. Also, they don't require custom trial and error bending like clothespin springs.
The nice thing about the springs is they can be bent to supply the desired tension and then they will maintain it in "set and forget" mode for a very, very long time!.
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Thanks for all your work and the YouMagine contributions, foehnsturm! Some of us have lathes, milling machines and JB Weld epoxy so the workarounds you describe are no big deal. If you happen to have a BOM handy, your "starting points" for parts and materials would still be a procurement time-saver!
For printing flexible and perhaps other difficult to print materials, your relatively light weight direct drive extruder really does seem to be the way to go. Most materials can't be printed at PLA speeds anyway. It didn't take too long after I got my UMO 2-1/2 years ago for me to realize that the speed advantage offered by the light Bowden print head design is mostly moot with many materials when print quality is a priority--even when printing ABS to some extent.
Just posted the stl and step files at Youmagine https://www.youmagine.com/designs/modular-printhead-nema8-worm-gear. But still no BOM due to the reasons I mentioned earlier in this thread.
I'll do that in the near future. However there are at least three obstacles to overcome, which requires some machinery.
Most worm gear sets with module 0.5 have drive worms with a 2 mm bore. It cannot be widened to the 4 mm of the stepper shaft as the overall diameter is too small. So you have to machine down the stepper shaft to 3 or 2 mm or manufacture a small adapter with a 4 mm bore and a 2 mm shaft.
The usual drive gears (MK8 ..) feature a 5 mm bore. This would require a 5 mm shaft, ball bearings with 5 mm ID and widening the worm gearwheel bore to 5mm ... parts would become quite bulky and heavy. I took a 3mm shaft and made a bushing with 3 mm ID and 5 mm OD fort the drive gear.
The design offers not enough width for a drive gear with a set screw. I removed the half with the screw and glued the remaining part to the shaft.
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Thanks Daid! I'll try the RC.
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calinb - this is a known bug and is fixed by removing "support" I believe. As pm_dude suggests.
Ahh--so it is. I've confirmed it myself. Thanks, gr5 and pm_dude!
Sometimes I just lazily leave support on when I know it's not going to be generated anyway. Unfortunately, the last time I ran into this bug, I needed the support too, and ended up building a brim into my solid model..
I've often made multilayer stepped brims in my models for maximum hold down. I just noticed that a "fillet" brim option is available in Kisslicer 1.5 beta1 now, but I've not yet tried it. Stepping the brim closer to the model as it climbs up the part a few layers is one of my often used tricks with nylon.
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This part has a tapered outside surface. Is there an easy way for me to get Cura to generate a brim that actually serves its intended purpose (holding the part to the bed)? I've run into this problem several times and usually just create my own brim or other bed adhesion-promoting structure into my solid model, but Cura should handle this!
Thanks,
-Cal
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I remove it from the spool, tie the coil with a fabric tie to keep the ends from popping loose from the coil and touching a heating element, and put it in a convection oven for a few hours. I've used both "normal" heat mode and the convective mode and I don't know whether the convection helps to more evenly burn off the moisture or carry it away, but it doesn't seem to hurt. I put my large desiccant bags in there at the same time.
I try to set the oven temperature just over the boiling point of water to speed things up, but 100 C is well above the glass transition temp for nylon. Any kinks in the nylon can result in a "set" in the filament after it cools so make sure the filament coils are nice and round. Using water for calibration and also a laser thermometer, I've found the dial on my oven (and the laser thermometer) to be fairly accurate.
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Maybe the community can think of building up a database with result data?
Perhaps this would be possible, but from my experience printing Taulman 618 and Oregon brand plain green trimmer line, one would need to control the water content of the filament to obtain meaningful comparative results. I've found very dry 618 (which prints much clearer/less foggy than typical 618 filament) to be much stiffer and harder than a typical 618 print. Fully dried nylon does not emit any visible water vapor from the nozzle--ever, but the translucent and shiny surface reflective quality of the printed part (and improved clarity--even in thick areas) is the main indicator that I use. The filament cannot be left out of a desiccant bag for more than a few hours after drying in order to achieve the stiffest and hardest possible print. Dry filament also improves bed adhesion on my Garolite bed.
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My BKM (best known method) is:
1. Kapton or PET tape. (PET is thicker and can sometimes last longer to achieve an "aged surface," described below.)
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2. ABS "juice" (ABS dissolved in MEK but not so viscous that it can't be wiped-on with a paper towel).
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3. Heated bed.
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4. Fan off for the first few lawyers.
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5. "Aged surface" (Your first couple of prints using the above setup will not adhere as well as the third or subsequent prints. After installing any fresh tape, print a couple of thin, sacrificial "seasoning" sheets that cover the entire footprint of the upcoming models. Being thin, they will be relatively easy to peel off the bed and you can evaluate how well your bed is aged/seasoned by how hard they are to remove.
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6. Nearly perfectly flat base/supporting surface for the glass. Even fairly thick glass bends when clamped to anything but a planar surface. I use precision Mic6 aluminum tool plate material for my hot plate (under the glass).
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7. Very fastidious bed leveling (in order to benefit from #6)
Note:
Once ~2mm to 5mm of Z height has been built, the bed heat may be reduced and fan used, as needed, to reduce other shrinkage effects "waisting" or narrowing of the part mid-way up. I use a heated chamber (bubble wrap tent) for ABS and I adjust the ambient air temperature in the tent by changing my bed temperature. Though I might set the bed temperature at 120-130C or so for the first few lawyers, I've found that I can later reduce the bed temperature to as low as 70 C without incurring a loss of adhesion of the part to the bed. My ABS process (bed, chamber, and nozzle temps and fan control) can be very complex, depending on the part.
Optional:
Designed-in model features like tall air dams (skirts), corner pads, and multi-layer stepped brims, but I usually don't need to resort to using them except when printing nylon (on Garolite).
Be advised:
When using techniques 1-7 on large models, I have broken two glass bed plates in removing the part from the hot swappable glass. Bed adhesion can be very strong, complete. and perfect! I do not recommend expensive borosilicate glass for this reason. Cheap window pane glass is manufactured using the float process, inherently flat, and perfectly acceptable.
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Yes--I did the CAD in inches, due to the legacy of the part's target design, My 0.002" slits are about 0.050 mm wide. I found that 0.001" slits were ignored by Cura, as I recall, and my strategy was to use the thinnest slits possible. At about 10 times thiner than a line width, the slits don't seem to introduce gaps in the fill. I think every slicer I've ever used produces inside cavity dimensions that print at least a bit too small anyway. (Screw holes are always too tight, for example, if not created oversize in the CAD).
I mostly used the Repetier-Host gcode editor and viewer to determine how the slit spacing affected the tool path. If I increased the spacing, the "fill" (to Cura it's actually walls) became less than 100% and I could increase the spacing distance above 0.050" (1.27mm) to obtain less than 100% fill, if desired.
My Cura Shell Thickness setting was 1.2 mm and my Nozzle size was 0.5 mm so Cura lays down two lines to make a wall. Thus it makes sense that Cura lays down two lines between every slit, which fills the gap very well between the slits.
The slit width is about 8% of the line width so one might expect the "fill" to be slightly sparse, but it's not the case in the actual part. It appears to be just as dense as 100% normal fill and, as I said, I think Cura and all the other slicers tend to generate gcode that results in over-extrusion around cavities. Normally I find this behavior to be really annoying, because I make mechanical parts that must hold reasonable dimensional tolerance, but in this case, I think I've leveraged this typically undesirable quality to do something useful.
In general, to obtain a solid region within a part, I recommend using the same size slits I used (0.050 mm) but space them apart by your Shell Thickness. You might have to tweak the spacing a little here or there to obtain a nice, even toolpath. The Cura and Rep-Host gcode viewers can help to evaluate the results.
calinb, thanks for the trick, very usefull.
maybe a stupid question but what do you mean by 0.002" ... is it 0.002 inch ?
Is there a relation to the used wall thickness you use? do you need to increase or decrease the cut size and distance based on it? How thick did you make the sollid top/bottom layer?
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The results are exactly what I wanted! Yes--of course I could make the model hollow, but that's not what I wanted. My goal was to print a part with 20% fill, except around the one screw hole where I wanted to print solid plastic. By placing slits in the model, Cura generated a dense tool path around the screw and the result was 100% fill in just that one place. Printing the part with solid fill everywhere would result in too much shrinkage and warpage in a nylon print. (Nylon is worse than even ABS in shrinkage!)
It's perfect the way it is and I was just sharing a technique rather than posting a request for assistance.
Ah, right, that makes sense. If your good with some CAD software, you could make the model hollow, which should force cura not to fill those parts.
You could also try to play with the fix-horrible settings a bit, might be that it removes the weird results due to the slits.
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Thanks for sharing. Any image of the printing to share? :mrgreen:
Sorry. The part is already installed and not readily available for a photo shoot. It's also a cover for a Winchester Model 70 bolt action rifle mag well and some people tend to spin into tizzies when the subject of printing gun stuff come up. I certainly wouldn't want to infringe on anyones "right to not be offended" or frighten anyone by posting a photo of the actual firearm with the installed part.
This part is no longer commercially available and my options were to mill it from metal or CAD it up and print it. Though I'd prefer a metal part and will probably mill one someday (maybe if I ever upgrade to a CNC mill), the nylon part is perfectly functional.
Here are a couple of the solid model CAD screen shots. The slits are 0.002" wide. The slits are covered with a solid CAD extrusion (not shown) so the slits don't come through the top skin, though that might not be a problem, I did not wish to interfere with Cura's normal top skin tool path generation.
Here is Cura's layer depiction from a mid-section slice from the area of concern. As you can see, Cura lays down walls instead of fill, because of the slits. This results in only this one area being 100% solid plastic.
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You could also try to increase the wall thickness from 0.8 to 1.2 and print 5% infill. This gave great results with PLA (Very light prints, but freakishly sturdy).
I'm already using 1.2 mm walls. The center of the part needed to be more resistant to the compression force imparted by a tightened (~40 in-lb) 1/4-36 screw in one area. The walls and sparse fill cross hatch did not provided enough support. Being nylon, the part wasn't even close to breaking, but the distortion, compression, and resulting protruding screw length on the backside of the part did not make for a satisfactory result when I attempted to place the non-reinforced part into service.
UMO B&B Manufacturing 298MXL025G Replacement Long Belt Set Review
in Third party products & modifications
Posted · Edited by Guest
I suspect that more than a few members here may have older UMs with aging stretched belts and might benefit from my experiences with belt replacements.
I removed my short belt drive mechanisms and replaced them with direct drive over a year ago:
https://www.thingiverse.com/thing:145544
You can checkout the "Made" link in the above page for my photos and notes. After installing the direct drive components, my UM became quieter and it required virtually no belt adjustments. (I re-bent my clothespin spring adjusters once.) I've tried several cool-looking printed manual tensioners, but I prefer the self-adjusting long belt clothespin spring tensioners, barely ever require any manual adjustment or maintenance.
Almost immediately after assembling my new UMO over three years ago, I felt the supplied belts were a touch on the long side. After a short break-in period, the 3 mm screws and nuts in the belt "claws" of the slider blocks ran out of their extremely limited adjustment range. I suspect the screws and nuts were added by UM designers when they discovered that the claw did not result in sufficient tension of the 300 mm long belts and supplies of a slightly smaller belt size were problematic, due poor market availability. Regardless of the reasons for the 3 mm hardware, it is really a poor excuse for a belt tensioner!
Thus I ran perfectly satisfactory, but kludgy-looking, clothespin springs for over three years. Recently, even bending the springs as much as possible, to maximize the tension of my aging belts, resulted in the springs rubbing gently on the UM's frame and still somewhat inadequate tension. (I could no longer "jump" reliably at 300 mm/sec!) I knew it was time to replace my long belts.
Rather than buying 300 mm replacements, I decided to special order 298 mm belts from B&B Manufacturing in the U.S.:
http://www.bbman.com/catalog/product/298MXL025G
Unfortunately, BBMan charges some pretty hefty extra shipping and handling fees but also discounts quantity buy levels. Accordingly, I ordered 12 belts to more favorably amortize the $17.42 USD shipping and handling charges, which is an outrageous sum for an order quantity that fits in a medium size envelope! The total charges, delivered to my door about two months later, were $63.26 ($15.82 per long belt set), but now I probably have more than a lifetime supply of UMO belts!
The 298MXL belts are the perfect size for use without any extra 3 mm claw tensioner hardware. (The wooden claw part alone results in perfect tension.) The 298 belts were slightly more difficult to install than the original 300s, and they were on the tight, but still acceptable side, in a belt pitch tone test before break-in (I think tone is the best way to check UMO belt tension), but they are perfect after a couple of prints worth of break-in time:
(I don't know why UM doesn't emphasize the above method, because any belt tension evaluation that is based on belt deflection depends on providing a known and standard pull force on the belt!)
I expect to get maximum service life from these belts, because no extra tensioner is needed initially, as it was with my original UMO 300 mm belts. I'll probably add my clothespin springs again, when necessary, for set and forget convenience, but the original 3 mm claw hardware could also be used to extend my 298 mm belt service life beyond what it can accomplish in tensioning the original belts too.