Kit Mods & Safety & Awesomeness

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PartDaddy
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Kit Mods & Safety & Awesomeness

Post by PartDaddy »

Hi all,

Just a quick reminder about machine modifications and safety.

First, we like aftermarket products for our printers. The user should thoroughly understand how our machines work before installing aftermarket parts. This is especially true for the hot end. Our hot end presently uses a thermistor to give the control temperature feedback. With the current state of firmware, a malfunctioning thermistor can cause hot end run-away. We don't write firmware, so we have to consider what happens in a worst case scenario regarding thermistor failure. My solution is the use of a power resistor which fails before it can cause a fire. For this reason we do not recommend heater cartridges. Heater cartridges can reach very high temperatures before failing and will typically cause a fire. For safety sake, we always recommend building our machines according to the manual before upgrading.

Since starting business in 1996, I've designed motorcycle drag racing parts, a bunch of cool paintball products, and now especially 3D printers. A little insight on my design objectives are: 1) safety 2) performance 3) aesthetics without sacrificing 1 or 2. I am fortunate to have a really skilled team who make up SeeMeCNC and we're all thankful to all of YOU who support and use our machines.

We understand a desire to blaze a 3D printing a trail of your own and we want it to be a great experience. Our forums are like the wild west and that is a part of what makes all of this fun!
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Re: Kit Mods & Safety & Awesomeness

Post by Captain Starfish »

Sounds like a cop-out to me.

I don't know what the latest state of play is with the Max (mine's a V1), but wrapping resistors in foil and jamming them in a hole is a hokey, messy, unreliable bodge job which may save a buck and may self destruct well before a fire but, quality wise, it lets the rest of the machine down. Simply jumping on a forum and saying "Don't do this" is like saying "You should walk to work instead of driving because it's safer". It might be safer, but it's going to be ignored by anyone that wants to get anywhere anytime this week.

I'd suggest that you've not met a duty of care with this thread, if that was its intent. Just looking around at the number of people doing upgrades and that the #1 upgrade is getting a real hot end, I'd guess that a "reasonable person" could be expected to completely ignore it.

Sorry, PartDaddy - if a student came to me with your hot end I'd probably give them an encouragement award, extend the project deadline (they'd had a go, after all) and tell them to try again. If they then pulled out the "safety card" as an excuse for it I would outright fail them then and there and suggest they consider a career in sales/spin instead of engineering. An example of doing it right: after the messy, "wtf moment"-loaded assembly of the SeeMe hot end when I first got the machine, putting together the E3D hot end was glorious. Neat, tidy, felt right and engineered rather than just slapped together with silicone and foil.

In the real world, cartridges are what people use to heat hot-ends. There. I said it.

If that, in your mind, creates a safety hazard that isn't adequately dealt with by the general rule of "Don't print unattended. If printing at home overnight, throw a fire alarm over the top of the unit" etc, then deal with the engineering problem a little more gracefully. Non-flammable effector platform might help. Or a thermal fuse which melts and cuts power to the cartridge over a certain temperature. If not available off the shelf, all you need is a bead of the right alloy of silver/lead solder for the temperature sitting between two wires in some kind of can. Or a smoke alarm cutout for the power.

Keeping the unit price point is a struggle, I know. But the very act of offering these for separate accessory sale reinforces the message that thermal runaway is a real risk with these machines and that owners need to manage that risk somehow.

Pardon what may come across as a belligerent, cranky post. But I've seen enough blanket "cover my *rse" stupidity in various company/agency policies this week to make this the straw that prompted a response, and you're copping it for all of those guys too. Sorry.

The Rostock is a fantastic bit of kit at any price, and that your efforts and those of your team have led to a brilliant bit of gear for a grand just blows me away. Keep up the great work sir, and I hope you find a real solution to the thermal runaway issue soon because a decent hot-end would make a great machine even greater.
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Re: Kit Mods & Safety & Awesomeness

Post by craftymethod »

Our machine is designed to be upgraded, so don't upgrade?

:P


Adding a clause if using an upgraded cartridge system then make sure you also do X seems like a good solution, Leading hotend manufacturers use them for a reason and in the end, its up to us to make them safe.

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Re: Kit Mods & Safety & Awesomeness

Post by IMBoring25 »

These are machines built at home by hobbyists with varying skill levels and attention to detail out of non-UL-listed components. Considering all the "moving parts" in the system, thermal runaway is but one of dozens of ways things can go very badly, melted bed screw terminals being one I've experienced twice with my Mendel and that I've seen others report on their Maxes. The number of fail-safes that would be required to provide non-illusory safety against all the potential failure modes for unattended printing would be significant.
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Re: Kit Mods & Safety & Awesomeness

Post by Polygonhell »

Thermal run away is a very real problem, happened to me on my first ever 3D printer, and as noted above with the supplied resistor, the worst case is pretty much a destroyed hotend. That's not the case for the usual 40W heater cartridges, they will get hot enough to melt aluminum before they fail.

Heater cartridges are a relatively new phenomenon to the hobby, they only started being prevalent a couple of years ago, and for whatever reason, the commonly available wattage was 40W, it's way more than almost any hotend needs to melt itself. I'd note that E3D have downsized the ones they use now.

Now I've never liked the stock hotend, and I run hotends with 40W heater cartridges all the time, but I also run a JHead with the supplied 5 OHM resistor heating element, and never had it or the resistors in my SeeMe CNC hotend fail during normal use.

My guess is some recent incident or story prompted the original post. As users we tend to get enamoured by the upgrades we use, and rarely are the risks communicated to new users, so I don't see these sorts of posts as a bad thing. Though they do come across as a bit late and a bit CYA given the amount of time users have been espousing the merits of heater cartridges here.
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Re: Kit Mods & Safety & Awesomeness

Post by PartDaddy »

@Captain Starfish
Rant, it's ok. :twisted: If I'm not criticized for something, I must be perfect? Hack away. My point is, "The user should thoroughly understand how our machines work before installing aftermarket parts." The greatest part of open design is hacking and making it do what you want.

Here everyone, take a moment and experience what it's like to be SeeMeCNC:
https://youtu.be/VxKvHaKFIR0?t=1m33s

Our hot end hasn't had anything to do with foil wrapping for 2 years. Yes, our first printer in 2011, the H-1, had foil in the hot end (sigh). People blew fuses and it caused a lot of headaches. It was a bad idea and never should of made it to the RMAX project at all. Unfortunately, it stuck around and was put in the first RMAX v1 kit instructions by mistake. It was removed from the manual no long afterwards in 2013. It is my opinion, the foil wrap is highly unlikely to cause a fire. It was highly likely to blow a fuse and cause frustration (my bad).

@craftymethod
My point is, "The user should thoroughly understand how our machines work before installing aftermarket parts." I did not finish a thought, let me edit my post above to say build it our way first, then upgrade.

Hopefully I'm clearer about what I'm say in the future. :)

@IMBoring25
I've never seen a heated bed failure. Could you link? I know the screw terminals can be an issue once in a while on the RAMBo. I realized after I initially posted what you mean. Yes, safety is an illusion. I have stories.

@Polygonhell
You have quality input as usual. The only late posts are the ones from whoever sells heater cartridges. ;)

Fish & Hell: you guys have an amazing presence on the forum. Boring / Crafty - I still have more posts than you. :D

Someone has to say something. It would be irresponsible of me not to point out a something which COULD cost a life and is associated. Here's a story from 2008. I donated a bunch of paintball products to a fundraiser for this: http://www.starnewsonline.com/article/2 ... G/71209002" onclick="window.open(this.href);return false; . I'm sure glad this fire had nothing to do with something I've been involved in. I'm not sure I'd be able to come to work tomorrow.

Here's the email I received, I XXXX out names, but you can get them from the article:

Sent: Thursday, January 24, 2008 11:10 AM
Subject: Event Sponsorhip- ref Charity Raffle

Sir,
My name is xxxxxxx xxxxxxxx. I am the Captain of Team BeBop, a scenario team based out of Virginia and North Carolina. My team and I have run several events in North Carolina and one in Virginia in an effort to raise money for the team. Currently I am contacting you in reference to an event my team will be running on February 9, 2008. This December we heard tragic news from a team that we have played along side and who has loyally supported BeBop's games, one of their members, Daniel Xxxx had a horrific house fire. Daniel lost his two young sons, he and his daughters are still in the UNC Chapel Hill burn unit. His house was a total loss along with all of their possessions. The Bell family has no insurance and no outside source of income. In an effort to aid his family BeBop is attempting to hold a charity raffle for the Samantha and Daniel Bell fund, the fund is being managed through the xxxxxxxxxxx. All monies raised from the raffle will go to this fund. Daniel is a member of Port City Militia Paintball team and the team will be coming out to the event to aid in reffing. The event is Battle of the Bulge II held at Black River Sportz in Angier, NC. http://www.brpaintball.com" onclick="window.open(this.href);return false; . In order to make this raffle a success we need support from the paintball industry, we are asking for anything at all that your comapny can do to aid us in our efforts to help the Bell family. We will be adding direct links from all of the companies that support this event to the advertising for the event as well as flying banners from any company who sends us one. Jason "Fooly Bear" Lindberger who writes for Action Pursuit Games and Paintball 2 Xtremes will also be there covering the event and we will do everything in our power to make sure all of our sponsors are mentioned in the articles Jason will be writing. Jason has covered several events for us in the past, with the latest article in this months Paintball 2 Xtremes magazine. Thank you in advance for anything you can do to help us in this endeavor. Below are the the links to the news story.

http://www.starnewsonline.com/article/2 ... G/71209002" onclick="window.open(this.href);return false;
http://wwaytv3.com/two_children_die_in_ ... re/12/2007" onclick="window.open(this.href);return false;

Phil xxxxxxx
DCA King
Captain and Founding Member Team BeBop

---------------------------------------------------------------------------------
In the mean time, I'll try not to think about fire, and just cover my ass.
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Re: Kit Mods & Safety & Awesomeness

Post by Eaglezsoar »

To Captain Starfish - Boy are you cranky!
But I do agree with everything you said, the resistors are and have been obsolete
and should have been replaced with the cartridge heaters some time ago.
When I replaced my resistors with the cartridge heater I discovered a new problem, what to do with the empty hole?
I use mine to heat my salami but if you don't have a small salami as I do you will have to heat something else.
Problems, problems, problems.
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Re: Kit Mods & Safety & Awesomeness

Post by PartDaddy »

Um, Carl, we've discussed it and there isn't any need to return your old hot end...
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Re: Kit Mods & Safety & Awesomeness

Post by Eaglezsoar »

PartDaddy wrote:Um, Carl, we've discussed it and there isn't any need to return your old hot end...
I hope you got a good chuckle!
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Re: Kit Mods & Safety & Awesomeness

Post by PartDaddy »

Oly, JJ, & I were nearly in tears..
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Re: Kit Mods & Safety & Awesomeness

Post by 3D-Print »

There should be a way in which the motherboard monitors the current draw. If the current draw isn't variable or intermittent (I.e. a constant current with a run away hotend) it shuts it down. This would prevent a runaway system/hot end.
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Re: Kit Mods & Safety & Awesomeness

Post by geneb »

Current draw is a poor measure, even if the board could do it. (It can't.)

There's two things you can do to make a controller be safer.

1. Use FETs that don't fail "on".
2. Place a board-controlled relay between the FET inputs and the power source, thus giving the board the ability to deny power to the hot end and heated bed, regardless of the type of FET used.

The rest of it is just a software problem that either has or can be, easily solved.

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Re: Kit Mods & Safety & Awesomeness

Post by cope413 »

I'll offer my $.02.

I know the SeeMe guys know I'm a huge fan of E3Ds. There are certainly two sides to the resistors vs. cartridges discussion. I, for one, won't be trading in my cartridges on 15+ machines any time soon in spite of the fact that this can happen
P1070228.jpeg
P1070229.jpeg

but I'm still fully on board with Steve's priorities of 1) Safety and 2) Performance.

I think most of the safety issues could be resolved with 2 fairly simple solutions, and would allow use of cartridges with a much higher degree of safety

1) Update the firmware to repetier .92+ or Marlin in order to utilize the Thermal Runaway protocols
2) Use a two-thermistor setup.

There is no such thing as a 100% failsafe, but this would add a fairly significant level of safety not currently present on the machines, and would cost virtually nothing aside from 1 thermistor, connector, wire, and however many hours it takes to get the new firmware dialed in.

Just remember that there is currently no failsafe for stupid outside of a few grains of lead and some powder.


That said, I'm going on 4300+ hours on my V1 - virtually all of them with a 40W E3D cartridge - and I've managed to only burn my fingers 713 times.
2015-10-01 15.12.02.jpg
I'm callin' that a win in the safety department.

Cheers!
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Re: Kit Mods & Safety & Awesomeness

Post by KAS »

Looks like a perfect application for a Thermal Fuse.


http://www.electronics-cooling.com/2012 ... uirements/" onclick="window.open(this.href);return false;
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Re: Kit Mods & Safety & Awesomeness

Post by Captain Starfish »

New day and a new (slightly less cranky) perspective.

I'm glad the foil is gone. If I wasn't being a lazy anger rampage monkey I would have checked my facts before launching into that bit.

And the warning is valid. Kinda like "don't install cruise control in a car until you know how to drive".

I think the real warning should be a reminder of the fire risks of these machines, even as supplied. I will not leave the house, not even to run down the shops for some milk, when I'm printing. There's no smoke alarm in the study with the printer but there is one right outside in the hallway. But I have friends with printers that will happily kick it off in the morning and go to work, expecting it to be done when the get home. I've given up pointing out the risks in this, but now I might point them at this thread and your link to the fire email just as a reminder.

One work client of mine has a CreatBot and they're limited to 8 hour prints. Anything bigger and they break it down into smaller parts to be fitted together after printing over multiple days. We looked at ways of setting up so they could print overnight but then they got sick of paying me for that and I moved onto other projects - it's still unresolved. But we were getting somewhere with thermal cutouts and smoke detectors wired to power relays and a powder fire extinguisher.

I don't trust the resistors to fail fast, either. You have a heat source surrounded by combustibles and all it takes is for a couple of things going wrong to stack up then suddenly you have a fire. Whilst that's the nature of the beast and it's really a problem for the installer/operator to solve rather than SeeMe, I think if fire is the issue then discuss the fire rather than the modifications which are just one of many ways to increase the risks of such an event.

Keep up the good work, the good info, and the good laughs, guys.
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Re: Kit Mods & Safety & Awesomeness

Post by PartDaddy »

Lol, starfish. I agree with you.

The E3D guys are a brilliant duo and make a fine product. I'm glad to see constructive posts here.

BTW, I put a dab of ointment in my eye to heal the poke wound obtained while reading your earlier post. I'm okay now.

Great melted hot end pick cope413. And it's true, even a redundant system doesn't always save the day. Now give me a day to understand your philosophical statement at the bottom of your post (which has a lot of really big words). :|
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Re: Kit Mods & Safety & Awesomeness

Post by 3D-Print »

geneb wrote:Current draw is a poor measure, even if the board could do it. (It can't.)

There's two things you can do to make a controller be safer.

1. Use FETs that don't fail "on".
2. Place a board-controlled relay between the FET inputs and the power source, thus giving the board the ability to deny power to the hot end and heated bed, regardless of the type of FET used.

The rest of it is just a software problem that either has or can be, easily solved.

g.
Awesome. Some way or another monitor for a failure and build a safety mechanism.
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Re: Kit Mods & Safety & Awesomeness

Post by cope413 »

PartDaddy wrote:Great melted hot end pick cope413. And it's true, even a redundant system doesn't always save the day. Now give me a day to understand your philosophical statement at the bottom of your post (which has a lot of really big words). :|
Decipher it and you get 5 gold stars and you're halfway to a philosophy degree that all of your friends can make fun of
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Re: Kit Mods & Safety & Awesomeness

Post by JFettig »

The real problem here is not necessarily the heating element but the measurement device. A rtv glued and kappton taped thermistor is an unacceptable solution. Even the solution E3d uses is also unacceptable in my opinion as I have had that fail too. These things are far too fragile for the diy community who really aren't diy-ers.

A proper solution would be a screw in thermocouple, they sell them in the m6 variety very cheap. Another solution that isn't as good, but still miles better is the screw in thermistor.
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Re: Kit Mods & Safety & Awesomeness

Post by johnoly99 »

True JFettig but the screw in thermistors are just M3 brass (usually) standoffs with a thermistor expoxied into the female threaded side of the standoffs.

So here's where we're at as of this early morning guys. Johnny from UltiMachine is coming to the shop today (for the weekend actually, for a vacation, why to Indiana? who knows lol). He has some ideas on the safety front that can/will be worked into the electronics in the future, but ALSO he has a guy named Tonokip (yeah, THE reprap tonokip for you reprap nerds ;) ) that pushed some of the safety code into repetier. We were testing it a little while ago and had some issues that we needed to address before we can make it live in firmware. DO expect there to be a firmware update in the next 2 weeks or so to have the sanity check for the heating elements. This alone should, and we'll have tons of testing before we 'ship' it, solve a lot of thermal runaways. However, in the case of the two most recent desktop 3d printer issues we've seen, it would NOT have prevented those. External forces like heat lamps and insulation foam, well, we can't write software to make glue hold etc.... Stay tuned, as we're mostly all hands on deck to add more layers of safety and concern to the hotend, but also remember, copes pics could be much MUCH worse had he not caught them in time before they fell on to the carpet :o
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Re: Kit Mods & Safety & Awesomeness

Post by geneb »

For those interested, know that you could easily add on a cutout relay to the RAMBo. It would live on a secondary board of course, but you'd only need a single free pin on the RAMBo to do the job. :)

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Re: Kit Mods & Safety & Awesomeness

Post by PartDaddy »

The independent cut out relay circuit Gene mentions in conjunction with a resetting thermal fuse really looks like one of the best solutions. It could send a reset to the control as well as an 'all good' signal. Even cut all power to the machine. The advantage here is cutting power is independent of the control.
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Re: Kit Mods & Safety & Awesomeness

Post by Captain Starfish »

Not a bad idea, although if a faulty RAMBo caused the issue then having the safety linked to it would not necessarily help.

We looked at a one-shot thermal fuse on the hot-end to simply open the contacts on a twin NC relay that cut power to the entire machine in case of a runaway - if you could use a resettable one even better. But having a dead simple, completely isolated, separate circuit well away from any logic or processing appeals to me.
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Re: Kit Mods & Safety & Awesomeness

Post by KAS »

Interesting enough I was looking for a way to turn off a 24v 750w meanwell power supply in case of a runaway Onyx. Ordered these almost two weeks ago, should be here by next week.

I like the idea of having a standalone system able to turn off or kill the output connection of the power supply.

I'm sure these aren't quality Fuses, but it comes with enough to test various ranges for a proof of concept.

http://www.ebay.com/itm/251494997789" onclick="window.open(this.href);return false;
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Re: Kit Mods & Safety & Awesomeness

Post by Holy1 »

I am using the repetier 92.3 version that has the watchdog feature. If there was a runaway situation it simply decouples the power to the hotend. I tested it by pulling out the thermistor when it up to temp and sure enough it worked fine, powered off the hotend within a few seconds.

Is not the same thing?
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