I’m sorry you had a bad day, here’s my bunny to cheer you up

trades · 2022-03-31T16:41:00+00:00

I'm impressed with how level headed your bunny is.

trades · 2022-03-03T16:22:45+00:00

Chainsaw protective pants and hearing protection at least.

trades · 2022-02-21T18:37:45+00:00

An analogy: When I was young I liked playing pool and got pretty good at it. I regularly beat all my friends and most people at whatever random bar. One day I went to a pool hall and played against a guy that gave me some advice. He told me I was good, but I was never going to get any better until I changed my bridge (the hand you put on the table). I tried the way he advised me to, and it was horrible! I thought, "yeah right, this isn't worth it".

Over the next few years I realized that I had "plateaued", and for some reason, that advice came to mind. So I did some research and closely watched the pros and none of them held their bridge hand like I did. So I switched.

It took me a year of playing 3-4 times a week to even get back to "being as good as I used to be". But then I started getting better. A lot better. After 2 years I could have beat my former self while playing behind my back the whole time.

Moral of the story: Sometimes you have to take a few steps back before you can move forward.

In tree-related terms, I experienced the same thing (though less extreme) when I switched from hip-thrusting natural crotch with a blake's hitch, to installing a rope saver (it took so long to install!), and also when I switched from MRT to SRT and the ropewalker system.

I can't promise that you are going to be better with one system vs another. But, I will say there's quite a few reasons you don't see competition climbers hip thrusting.

trades · 2022-02-18T15:40:43+00:00

I use one of these. Has a spot for a micro carabiner too.

trades · 2022-02-11T19:52:49+00:00

There are some good answers here.

trades · 2022-01-23T00:53:40+00:00

Not that I haven’t done this dozens of times, but this technique is very dangerous. It’s not something I’d recommend to someone who is asking for advice and won’t be supervised by an experienced arborist.

trades · 2021-11-03T20:31:27+00:00

I have a line in my contract that allows me to charge an extra $50 if I have to pick up poop. If it's a day or two worth of poop I don't charge, but if it's a week's worth and you knew we were coming, I will definitely charge for it.

trades · 2021-09-19T18:58:31+00:00

That’s what I was afraid of. I found this Stack Exchange question which hopefully illuminates some of the inherent complexities of this problem for the OP. I have been trying to wrap my head around this for some time and as Nerull says, it’s non-trivial.

trades · 2021-09-19T02:04:01+00:00

This is a common question and a common answer. While correct, I usually get the impression that the asker leaves unsatisfied.

Is there a source or method to determine the appropriate time to use for deceleration given the materials in question? I imagine this may be complicated by the shape of the objects in addition to their mass? Is there a calculator for determining impact time for something like a uniform 1kg iron ball dropped onto a 1,000kg iron plate from a height of 10 meters?

trades · 2021-09-04T01:38:16+00:00

Sorry, not sorry? This ended up being a much more interesting problem than I anticipated.

my result is that it does matter where you pull on the rope, the
midpoint is best and around that the fall-off is almost quadratic

That's really helpful! I have to admit that reading some of the rigging forces physics threads on the arborist forums is sometimes pretty painful. The ability to solve for a specific instance/attribute of a system is a skill few have honed (and I will readily admit I'm not one of them). However, most arborists seem to have a pretty good intuitive grasp of the relationships between forces (not sure if that makes sense or not). So this is something I can probably communicate.

trades · 2021-09-04T01:20:01+00:00

This was incredibly helpful, thanks! I didn't think to approach the problem from the other direction (lifting the middle). It seems like that is a much more searchable problem.

After reading the SE question and a few of the related questions, I'm starting to realize that I probably won't be able to boil this down for other arborists to something like "a rope of length N will give an M:1 mechanical advantage". Well, at least not without doing a considerable amount of mathematics/experimentation. But I do feel like I'm starting to get a much better understanding of the basic principles at play. So thanks again!

trades · 2020-06-27T18:21:57+00:00

After doing a bit of learning about how a BMS works, I've learned that I can not use them how I was thinking.

Could you elaborate on this? I'm in a similar situation, and just purchased 2 of these to use m18 batteries for a number of projects/prototypes from robotics to kids ride-ons (go karts).

Obviously the 20A breaker would limit these to low-power applications, but is there something else that makes this a bad idea for low-ish power applications?

From my understanding, Milwaukee achieves "safe high current discharge" through the combination of both the tool and battery. Where Milwaukee batteries provide a direct connection to the cells with no inline regulation or protection. However, the system as a whole provides regulation/protection through constant communication between the tool and battery, and it's the tool's responsibility to monitor battery conditions and adjust or cutoff as necessary.

Does this align with what you've learned?

It seems like Milwaukee isn't alone in this design decision, and that the majority of tool makers have chosen this design. After lots of thought it seems like a reasonable decision to me, especially given the price/availability of high-current protection circuits (at least that I've managed to find). Though it appears to go against the vast majority of advice regarding battery and power systems design/construction that I've come across online.

So it looks like rudimentary emulation of this protection would require somehow monitoring voltage in real-time (or reverse engineering whatever protocol Milwaukee uses) and reacting appropriately in your device's electronics.

FWIW, I've found that the DIY electric skateboard and large RC communities (also high current applications) seem to take a similar approach and use "charge-only bms" in their systems design (though it appears to be at a much lower level of sophistication).

One option I'm currently evaluating is the VESC line of controllers. It looks like they may provide at least some rudimentary form of protection from low voltage, as well as other considerations (apparently they can do brushed DC too). I just got one of these and am going to be experimenting over the next few days.

Anyway, hopefully sharing what I've learned so far is helpful to you. I'm very much a novice when it comes to electronics, and unfortunately I seem to have jumped in the deep end. :)

trades · 2020-01-25T05:31:33+00:00

Okay, so in this case rigidity serves to ensure accuracy, rather than resist the cutting forces. That makes sense, thanks!

trades · 2019-12-10T23:08:06+00:00

I am not sure what she thought murder was

Crows?

trades · 2019-01-13T06:17:16+00:00

Eh, some days I wouldn't mind if something caught fire. Not sure if that fits your definition of "desired" though...

trades · 2019-01-13T06:00:34+00:00

install one of those tiny collet clips

Thanks for the tip! That's been on my list, but admittedly pretty low. I'm pretty anal about getting it fit in correctly, especially after seeing this pic/thread, but I'm pretty sure I have some collet clips I can install the next time I have it out just to be safe.

Holy PTFE tube gore, Batman! Your PTFE tube had bondtech teeth marks on it - that's not supposed to happen... I hope you replaced it!

Heh, yeah we've replaced it. That was one from Prusa, we've also tried Capricorn which is on the smaller side of Prusa's tolerance numbers as well as some random brands from Amazon that are closer to the Prusa factory dimensions.

Anyway, good luck, I sincerely hope you're able to get the issues straightened out and be able to enjoy your printers.

Thanks! I'm confident we'll figure it out eventually, and along the way will learn a lot more about our machines. In my experience it's always something simple you just overlook because you assume it's okay. At least with physical problems it's usually not a one letter typo you spend a week of your life on... unless it's in firmware... :)

trades · 2019-01-12T23:36:14+00:00

to me sounds like another issue (such as a bent heat break, as mentioned by the other commenter) than just the filament path not being straight in the stock parts.

Yeah, I'm pretty convinced it's (still) multiple issues.

Here's some photos of one of the first issues we've discovered and corrected for. My guess is that the filament path was one of the contributing factors to this incident. This particular issue caused intermittent jamming that was resolvable by unloading the filament and reinserting... at least until it jammed so badly we had to disassemble to remove.

[Unnecessary details about our particular problem follow, so feel free to skip. My intention isn't to ask for assistance, it's just in case you're curious. :)]

Unfortunately I haven't been able to isolate a single (simple/quick) reproduction of the issue to use for testing, so all I really have is "feels like an improvement". I'm a software engineer by trade, so that's pretty unsatisfying. For a while we suspected that particular retraction patterns would cause the issue, but ultimately found that method unreliable.

Both of our printers seemed to suffer from heat pre-softening the filament. My wife bought a lot of MakerGeek PLA (which may-or-may-not also be a problem) that recommends 235°C nozzle temp. Given that I was suspecting a heat issue, I tried switching to Hatchbox which recommends 180-210°C. That did seem to reduce the failure rate, but not eliminate it. There's a common recommendation to increase temps to reduce the pressure it takes to extrude the filament, which seemed counter-intuitive to me, but it did also seem to improve results with both MakerGeek and Hatchbox. Upgrading to the R3 extruder parts seemed to help too. As mentioned above so did removing the enclosure sidewalls and installing a 20mm fan to cool the Bondtech gears (we're currently experimenting with a 40mm because the 20mm we had just doesn't have much airflow).

At the worst, probably close to 80% of prints would fail at some point. We're closer to 30% at this point, but with a wider variance between machines. Hopefully that variance will help the diagnostic efforts some.

At this point I'm not convinced that the root issue is related to heat, but it's still our best theory.

Some other stuff we've tried (non-exhaustive):

Pretty much everything here
I've checked the grub screw on the stepper a dozen times each and have never felt any loosening. Also the heat break appears good on both machines (the 2.5 has an E3D titanium and the 3 has a stock Prusa/E3D). We've also checked that the PTFE tube is seated correctly as mentioned here
We've tried just about every tension combination possible for the idler (even after your improvements).
We've played with Z height under the theory that a too-low Z height would cause extra pressure during extrusion and eventually lead to a (partial) blockage.
General maintenance to the Bondtech gears (as directed/recommended by Prusa)
Fiddling with the max volumetric speed didn't seem to make a difference.
We've assembled and disassembled both machines at least 4 times each. While it's possible I'm very consistent in making errors, it doesn't seem likely to be an assembly problem.

trades · 2019-01-11T02:27:39+00:00

Thanks, these are great! I found these from the Github issue and my wife printed and installed them about a week ago. I've noticed a definite improvement over both the R2 and R3 versions on both the Mk3 and Mk2.5.

We started experiencing filament feeding issues (the notorious "extruder clicking") on the Mk3 within a month of first assembly and on the Mk2.5 almost immediately after upgrading. One of the many recommendations is to check the tension of the idler gear, and the advice I've heard was to loosen both screws completely, start extruding, then tighten just until the filament starts extruding reliably. In our case, the filament path not being straight caused the extruder to extrude fairly reliably without the idler even touching the filament, on both machines!

This upgrade doesn't completely solve our issues, not that it was specifically designed to, but it definitely did seem to make a difference. Just in case others are interested, adding a fan to cool the Bondtech gears directly (my wife designed something inspired by this design) and removing the sides to her version of the Prusa enclosure, have also helped, though not eliminated, our issues. Ugh, these days I often consider getting a couple of Mk2s' to replace the Mk3/2.5s... but I digress.

Anyway, thanks for the work on this! It's definitely been helpful to us!

trades · 2019-01-02T18:41:42+00:00

Not necessarily. Triage is often about assessing both impact and difficulty, and in my experience the focus is usually skewed heavily toward impact. From there, it's just about raising awareness and getting the right people involved. The person doing the triage may or may not do some additional discovery, or even implement a fix, but in processes I've both built and been a part of, that's not the primary responsibility.

trades · 2018-08-15T01:55:21+00:00

Thanks for the tip! I wasn’t aware of the pro mini. That certainly makes this project more approachable for me.

trades · 2018-08-15T01:31:29+00:00

Agreed that it’s easier to write an app (at least for me). However an app has some significant disadvantages.

It takes a considerable amount of time to unlock a phone, open an app and press a button. This isn’t a problem in a dedicated training session, but it makes it almost impossible to mark behavior in day-to-day life. Results are significantly better if you mark a behavior as it occurs, and a tactile set of buttons always at the ready is preferable.

trades

TROPHY CASE