VOTE - Repair the Big Laser

General
1

The Big Laser is Down hard. We need to authorize the purchase of $2000 worth of parts to make the repairs ASAP. Like Tuesday 8/20.

Lead Time for parts from China if we wait two weeks for vote approval gets us to Mid September or later for parts delivery.
Air shipment can be done, but costs are unknown and may not buy much time.

I’ve spent the last few days evaluating the damage and researching part sources on AliExpress. There are several very competitive and competent suppliers for these parts that I have used before.

We have a parts list on the web that currently totals near $1800. Laser Replacement Parts List I will continue to research suppliers in the attempt to get lower costs and better parts. They will go on the list.

There may be more to buy. We won’t know what electronics have suffered invisible damage for some time. Additional Purchases would be authorized in the future.

Please Note: Even if the Hive13 membership authorizes this purchase, The big laser won’t get fixed unless you also volunteer your time to help repair the big laser.
see the Laser TODO. list This is a big opportunity for you as a member to learn a lot about laser cutters. There is a lot more to laser cutters than a laser beam.

If you already have experience with Laser Cutters, we need your help to get this done.

PRO Buying Components ASAP

We can order parts next week for delivery mid September.

By the time the part arrive, we will have time to clean and prepare the carcass and test the electronics.

Assembly of the parts into a working laser can be done in September.

CON Buying components ASAP
We might get a better price on some parts.

Alternatives.

Buy New -

A new laser like our Big Laser GWeike LC1512 would probably cost more than the $6500 delivered that it cost in 2015. I’ve asked GWeike for a quote, but they are slow.

I’m betting that we all would like to check out other laser cutter suppliers and prices if we choose to buy a new laser. And if we do, the laser will not be operational very soon at all.

That project needs a leader. It’s not me.

A different Controller for the repaired laser is being discussed. This vote uses the MPC8530S controller and LaserCut2017 that we already own.

2

The Vote was approved for $2000 on 8/27. I’m continuing to scrub the Laser Replacement Parts List for better suppliers and lower total costs. Orders will be placed soon.

In order to answer the questions: How long will this take? and How can I help? a second project task page has been added to the Laser Replacement Parts spreadsheet.

We’re currently recruiting for people to take on tasks.

Ways you can help.

  • Project Management

  • Cleaning - See the https://wiki.hive13.org/view/Laser_TODO

  • Design the Lid Strut Replacement - The old struts are groaning. Should we just replace them or do a redesign? If left to me, the just get replaced.

  • Design a CO2 fire suppression system, so we never go through this again.

  • Test the electronics

See the Laser Replacement Parts List Tasks tab for more detail.

If you have suggestions on suppliers and or would like to work on a task please respond to this post.

3

Dave - thanks for the continued effort.

I’ll take ownership of the strut redesign. I’ll hold off on putting significant effort for the next week or 2, but i’ll add a “temporary” support so that we don’t have to worry about it falling down on anyone while they clean.

I’ll do my best to get the in by this time next week.

Cheer

4

Awesome!
For background I did the auxiliary struts and it was just an easy way to keep the lid from killing someone.
We were having difficulty finding that particular length with a higher force for not big $, so I grabbed a similar set (cheap) and mounted them in parallel.
I always thought a junkyard trip should be able to get a nice set from a Ferrari. :stuck_out_tongue_winking_eye:

Happy to talk more.

5

We oclosed on selling our Cincinnati home yesterday. I'll have some time after mid-September and into the fall now that we are based in Louisville.

I'll offer to engage with DaveV on some program management and will take on documenting the re-wiring work with a set of 2-D schematics. I'll also offer to take the lead on the CO2 fire-suppression upgrade.

JimD

6

Brad - I figured a junkyard would be a required visit for my solution. Should be able to find a large hatchback...

Jim - I have a single line block diagram for the lasers in my notebook that cover from the laser and stepper motors to the main drivers. If we are okay with that level of detail, we'd only need to go from the PCB to the control panel which should only be a couple of straight forward connections.

7

Might I suggest a counterweight/rope/pully solution to the lid instead of an air piston? Counterweights don’t have seals that leak and eventually give up…

8

Jim, I was going to offer to take this on. If you would like an out on this I’ll take it over. Likewise, if you’re excited about doing it I don’t want to steal your thunder.

9

Yes I think it is worth some discussion.
We talked about a counterweight system before. Weight/pulley or a simple weight on an arm.
Concern with weight/pulley is wear on the cable/rope and pulley binding. (You can go down a rabbit hole of anything failing.)
I really liked the counterweight idea that balanced the lid from a bar near the hinge that extended off to the side and weights were mounted on a bracket ~90 degrees offset from the lid CG. No moving parts but a bit bulky.
Of course pneumatic actuators are used on cars everywhere, hopefully would be easy to find an automotive equivalent and get a few spares. Those are designed for thousands of cycles and abuse.

10

I’ve been mulling this over and am leaning towards feeling that this (system CO2 fire suppressor) should be 100% manual and void of electronics. I think it should be a ball value or a button that releases gas. Doing it electronically sounds fun and nifty but prone to not working when you need it.

11

I am also against us creating an “automatic” system. Maybe an alarm system to buzz/flash if excessive heat/smoke is detected.
We are clever, but not really up to creating a safety system that people would rely on for possible life saving function.
Especially something as complicated as a laser that used heat to cut/engrave and then detecting if there is an out of control fire. I can imagine lots of false positives, lots of CO2, then the system being tuned down so it really isn’t effective.
A great big red button that floods the enclosure with a burst of CO2 sounds awesome! (along with the wall mount CO2 as a backup).
Safety systems are hard, and can actually setup a culture of non-safety if they are believed to work (and don’t).

12

IMHO; Like sprinklers, fire suppression should be an automatic response to fire.

  1. cut power to laser and exhaust ( don’t feed the fire ) Note: an estop doesn’t stop the exhaust, so fire suppression should also stop the fan.

  2. open solenoid to dump approximately 15 lbs of CO2 into the enclosure. at 8.7 cu ft / lb of co2 this would fill 100% of the enclosure.

Thermal switches from snapdisk are super reliable, (100k cycles or more) have many trigger temperatures available and they are under $10 in low quantities.
Dave B suggested using auto brake lines as gas feed tubes.

Of course there should also be a manual trigger, but true suppression should be automatic.

13

I agree that automated the back end is fine, but are you implying the the system would work like sprinklers and fire based on heat or "sense"of fire? If that’s the case, what would trigger the suppression system?

14

Maybe a compromise is in order here. Start out with a tank of CO2 feeding both lasers with a ball valve at each one that can be thrown open or throttled to control the burst. This would take literally minutes to set up and could be done by noon today. It would be stupidly obvious to anyone what to do with it.

Then we put on our propeller hats and engineer something spiffy that has a manual override.

15

Automation triumphs over human inattention and panic.

IMHO the manual CO2 fire suppression is already installed. It’s red and hanging on the post in the FabLab. Pull the pin and it’s ready to go.

Without automation there is little to no advantage of an installed CO2 distribution system over a fire extinguisher.

Good placement of valves and intuitive obviousness of operation are not trivial considerations as has already been demonstrated.

I’d trigger based on heat. Smoke detection would be problematic. There could be multiple thermal sensors which trigger at temperatures from 50C to 220C

I’ve used Therm-O-Disc brand snapdisk thermal switches in designs before. They are highly reliable, UL rated dead simple automatic switches for thermal control of up to 16A at 220VAC.

16

Just to be clear - I totally agree that automation would be great.

However, I do not see a simple and reliable system to detect the difference between smoke and fire. If there’s a simple sensor / tool that can do this, let’s do it!

17

This snapdisk switch example closes at 120F and opens at 110F. Other temperature ranges are available. There are also all metallic versions which would be fire resistant. These are in many furnaces and gas fired appliances.

When one of several thermal switches closes, it would close a relay(s) which would then take care of all the required functions. Stop power to laser and exhaust and trigger solenoid to release CO2.
You could use some AB DIN rail controls like on the compressor. This is basic industrial control stuff.

https://smile.amazon.com/Emerson-3L01-350-Snap-Limit-Control/dp/B00QW2880O/ref=sr_1_5?keywords=snapdisk+switch&qid=1567094068&s=gateway&sr=8-5-spell

18

Something to keep in mind, firing off a CO2 extinguisher in a closed environment will make the temp in there PLUMMET. We would want to check to make sure that something like that wouldn’t cause thermal shock to the glass laser tube and cause it to shatter. Potentially exuberantly shatter.

I mention this as someone with a scar from frostbite using a C02 extinguisher and is familiar with the temperature delta that happens.

19

Wow you all are blowing up my list today.

Tldr. skipped over a few messages.

And as proof that great minds think alike , we had our fire extinguishers and Fire Safety Systems being looked at today at work.

I wondered if there might already be a system designed for these lasers.
I asked them guy about a system for the laser cutter and I have a card and a name to call. My thought was if we found an already designed system it would save us a lot of time and effort over building and designing our own.
If nothing else perhaps talking with the guy could give us some ideas on which design to go with.

Thoughts?

NancyG

20

Hmmm... If we did that then what would we have left to talk about? :crazy_face: