Big Purchase: Laser cutter repair

[Lex Bailey]

TL;DR:

We want to fix the big laser cutter so people can use it, and maybe improve the small (K40) cutter slightly too.

We have options in the range of £520 to £840 that will bring the big cutter up to the kind of spec you'd expect if you'd spent upwards of £2,500 on a new machine and accessories.

See also: diagrams at end of email.

Laser Cutter Repair

We got a big broken laser cutter for free a little while before the hackspace moved. After some diagnosis, we found that the only problem is that the laser tube has suffered a total failure. This machine has a much larger cutting area than the K40, and could easily be fitted with a more powerful tube than the K40. It also allows control of the power level from software, which enables a faster workflow than the K40 which only has the manual power controll knob. Given that we have an easy opportunity to vastly improve our laser cutting capbilities, me and Baud have made a plan and would like to spend some money to execute that plan...

The plan is to get a 60W CO2 laser tube and associated power supply. We also plan to fit an air pump as the laser gantry already has the tubing in place for this that runs down to the bottom of the cabinet, which is probably where we will end up fitting the pump. This blows the dust away from the cutting zone to produce cleaner cuts. The K40 has one already. We’ve over-estimated the amount of tubing needed for this in case we need to mount it elsewhere. We have also budgeted for some miscellaneous fixtures and fittings, e.g. for connecting tubing, mounting things to the chassis of the laser cutter, etc. (Note that this does not bring the machine back to its original spec. The original tube, which has failed, was a much more expensive type of tube that costs thousands of pounds to repair or replace, we've explored that already. Replacing the tube like-for-like would be the ideal solution, but we didn't want to propose spending that amount of money. Swapping the tube for the cheaper kind is a far more reasonable cost for our use case.)

Optionally, we would like to buy a separate cooler for the laser cutter so the two laser cutters are completely isolated from each other. Not necessary but would be nice, especially as the proposed cooler would fit inside the laser cutter cabinet, allowing the laser cutter to be more easily removed from the corner for maintenance. If we buy a new cooler we’ll also need to get some more Deionised water. There is maybe 1L left in the existing container. If we don’t buy a cooler we’ll need to source an additional submersible pump for the existing cooler but the cost of that should be covered by our budgeted “Misc fixtures and fittings”.

We would also like to propose an option of buying two of the coolers instead of just one so that we can replace the existing cooler for the K40. This should free up some space as the proposed cooler is very small and should fit under/behind the desk the K40 lives on. The other benefit of this is that it's a cooler that's actually designed for lasers. Our current cooler was hacked together from an old office water cooler, which isn't designed to continuously chill water that's being heated by a powerful laser tube. So far this hasn't been a big problem for the K40's 40W laser unless it is being continuously used for long periods.

All of the cooling options are forwards-compatible so we can always make these optional changes at a later date for the cost of the coolers (plus misc costs of adapters etc.)

Finally, we’ll need to add extraction for the new laser cutter. Our proposal is to put a Y-joiner in the existing pipe and a non-return valve on each side of the pipe. This would allow both laser cutters to be run at once whilst not requiring us to add another hole in the ceiling in order to keep the same amount of airflow as we currently have. We’ll also need to add another duct fan on the output of the big laser, which will likely be mounted to a board attached to the two uprights for the shelf over the laser cutter. If we were to replace the existing chiller for the K40 then we would only need one 45-degree corner in the duct piping, we need an additional two to get up and over the existing chiller.

While small suggestions are welcome, please don't propose radically different approaches. We've put lots of time and thought into this design already, we'd rather not bikeshed other solutions to getting the machine working again, we're just looking for approval to spend the money.

Cost options

The total cost of the essential parts for this repair is £522.05. With the addition of one new cooler the cost would be £689.03 and with two coolers it would be £839.02. Again, all of these options are forwards-compatible so we could start with the cheapest and then upgrade at a later date if that's what people think is best (for example if we discover that the cooling setup can't keep up with the larger tube, or with both cutters running at once).

This is our first big spend since the move. Gav, let us know if any of these options is not doable in our current financial situation.

If you're excited by the idea of using the big laser cutter and think it's worth spending the money on, then please let us know which of the options you'd support.

As for my (Lex) own opinion: I think the £689.03 options is best, since the effort required to set it up is the lowest of all the options. It will be the fastest one to get going. (No hacking an extra cooling loop into the existing cooler. The new cooler will be plug-and-play)

Thanks,

Lex & Baud.

Visual summary of the three options...

Pictured is the ducting layout (without the extra bends to get around the cooler)...

[Lissa]

My short answer: subject to finance, I'd suggest going for the £690 solution, but perhaps testing it first by commandeering the existing water cooler if that is not prohibitive - just to prove it works before forking out more for the new chiller.

Some detail that would be useful to know, partly out of interest:

• Does the existing cabinet / your budget include safety interlocks like we fitted to the K40?
• What was the reason for the choice of a 60W tube (I assume it's tube length, but could have been cost?)
• Will any additional optical shielding be added/needed for the glass tube?  I recall the rear panel has a lot of vent holes and I'm not sure whether glass tubes emit more diffuse radiation than the metal RF unit (which for a class IV laser is still hazardous)
• Will the repaired unit run the same firmware / control board and just a different laser PSU and tube?

Many thanks to both of you for all the work you've put into this so far - it's fantastic to see a plan like this!

Cheers

Lissa

--
You received this message because you are subscribed to the Google Groups "York Hackspace" group.
To unsubscribe from this group and stop receiving emails from it, send an email to york-hack-spa...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/york-hack-space/CvJVibZE24uQRGP5yt7LrxOc8wK9DSPP34ZUkBVOBl7LOhsKb6x3AJOMZSTVVDCgU6GQnQKBue2vIBsmojQda-Wro6u3XfyTNzLtWPGmYLY%3D%40lexbailey.me.

[Lex Bailey]

Excellent questions, responses inline...

On Thursday, 11 July 2024 at 23:09, Lissa <york-hack-spac...@foxtails.uk> wrote:

My short answer: subject to finance, I'd suggest going for the £690 solution, but perhaps testing it first by commandeering the existing water cooler if that is not prohibitive - just to prove it works before forking out more for the new chiller.

We could do that, it is possible, but i'd prefer not to. This would mean opening up the cooling loop for the K40, which is currently working fine, and full of water, just to move it over to the other cutter, and then move it back again. That's two additional rounds of the unfun task of draining, breaking, joining, and filling a cooling loop, which includes getting the bubbles out of the laser tube. That's easy on the K40 where we can lift the whole machine quite easilly to tilt the bubbles to one side, but I really only want to do that once on the big machine if I can, since it probably means removing the tube from the mount to tip the air to one side.

Some detail that would be useful to know, partly out of interest:

• Does the existing cabinet / your budget include safety interlocks like we fitted to the K40?

Yes, the machine already has lid-closed detection switches, and an e-stop button. The controller also knows the state of both of these and provides helpful info on the LCD when an interlock has prevented some action.

• What was the reason for the choice of a 60W tube (I assume it's tube length, but could have been cost?)

Mainly just because it's the most powerful tube we can fit in there. It's not much more expensive than a 40W tube, so it makes sense to go for the extra power, to enable greater cutting speed.

• Will any additional optical shielding be added/needed for the glass tube?  I recall the rear panel has a lot of vent holes and I'm not sure whether glass tubes emit more diffuse radiation than the metal RF unit (which for a class IV laser is still hazardous)

We won't need any additional shielding. While it's not safe to be in the the path of the laser beam, it is safe to look at the tube while it's operating. I realise that makes me "a person on the internet asserting a non-obvious safety fact", so let me justify that answer: Some folks who went to the Newcastle Maker Faire back in ... 2016? may remember Just Add Sharks (now defunct laser cutter reseller) was demoing their prototype own-design affordable laser cutter, in which the laser tube was mounted on the XY gantry and so it moved together with the Y axis of the machine. You could clearly see the tube any time you were looking at the machine. They were happy to have this running while people visiting the fair were watching it go without any kind of protective eyeware. Pics of that prototype here: https://msraynsford.blogspot.com/2016/05/vanilla-box-prototyping.html I've also seen a 60W tube from another laser cutter that was operating with the case open. It had just been replaced, and was being tested and aligned. Neither me nor the people fixing that laser cutter had any eye protection, we were all fine. That was at cambridge makespace. The tube in our cutter will be right at the bottom, at the back of the machine, and the machine will be tucked in next to the shelves, so normally you won't even see any part of the tube. If people still don't like that idea, then we can put some opaque materials of some kind in the way of the holes in the laser tube area. I'm sure that won't cost much.

• Will the repaired unit run the same firmware / control board and just a different laser PSU and tube?

Yes! all the existing motion controll stuff works fine, and we have a software stack that works, so we see no need to spend money replacing those parts, nor spend time changing the firmware.

Many thanks to both of you for all the work you've put into this so far - it's fantastic to see a plan like this!

^_^ thanks

To view this discussion on the web, visit https://groups.google.com/d/msgid/york-hack-space/1d6b79537e846e62040b88d6902821ac%40foxtails.uk.

[Gavin Atkinson]

In a personal capacity, I think the £690 option is the best.  It would be a shame to spend this much on a new laser tube and then run it with our existing open-circuit cooling, with the risk that entails.

In a treasurer capacity, I think we need a breakdown of what's being propsed to buy - I'm not suggesting the design needs bikeshedding at all but I do think before spoending this much it should at least be sanity-checked to make sure nothing has been missed, there won't be any unforseen costs, etc.

Funds are pretty tight at the moment, and we're still slowly losing money monthly after the move, but if the large laser cutter can be repaired that seems like a worthwhile investment to me.  I'd like to do a full calculation on where this would leave us, but won't have time to do so until tomorrow - I'd suggest the 48 hours can't really start until we have an itemised list of what is proposed and where from anyway.

Gavin

[Lex Bailey]

Thanks Gav,

Yeah I should have included that in the original message and completely forgot.

Here is our shopping list:

Item	Cost (Unit)	Quantity	Total Cost	Source
Laser Tube	£149.99	1	£149.99	https://omtechlaser.uk/products/60w-co2-laser-tube-usb-0000-60
Laser Power Supply	£138.99	1	£138.99	https://www.ebay.co.uk/itm/326133502739
Laser Tube Mounts	£13.03	2	£26.06	https://www.ebay.co.uk/itm/166719974575
Air Pump (ACO-001)	£32.99	1	£32.99	https://www.ebay.co.uk/itm/351363691208
Silicone Tubing for Water Cooling	Approx £5/m	5	Approx £25	TBD when tube arrives (diameter of tubing needs to be measured)
Silicone Tubing for Air	Approx £5/m	2	Approx £10	TBD when air pump arrives
Extractor	£39.98	1	£39.98	https://omtechlaser.uk/products/industrial-exhaust-fan-duct-fan-for-laser-engraver-cutter-lap-0400
Ducting pipe	£8.99	2	£17.98	https://www.screwfix.com/p/manrose-100mm-round-ducting-1m/544gy
Flexible ducting	£4.49	1	£4.49	https://www.screwfix.com/p/manrose-pvc-flexible-ducting-hose-white-3m-x-100mm/18232
45 degree pipe corner	£3.19	3	£9.57	https://www.screwfix.com/p/manrose-45-bend-white-100mm/410gy
90 degree pipe corner	£3.29	2	£6.58	https://www.screwfix.com/p/manrose-90-bend-white-100mm/897gy
Y-pipe connector	£3.31	1	£3.31	https://www.screwfix.com/p/manrose-circular-y-piece-connector-white-100mm/23574
Straight connector	£1.80	1	£1.80	https://www.screwfix.com/p/manrose-round-pipe-connector-white-100mm/12697
Non-return valve	£3.85	2	£7.70	https://www.ebay.co.uk/itm/192906157518
Ducting clips (100mm pack of 20)	£21.22	1	£21.22	https://www.ebay.co.uk/itm/222606588769
USB extension cable	£1.39	1	£1.39	https://www.ebay.co.uk/itm/403989423359
Misc fixtures and fittings (connectors for air/water tubes, screws etc)	£30	-	£30	-

Plus if we do get the cooler, then also these:

Item	Cost (Unit)	Quantity	Total Cost	Source
Cooler	£149.99	1 or 2	£149.99 or £299.98	https://omtechlaser.uk/products/9l-industrial-water-chiller-lcw-3000-uk
Deionised Water	£16.99	1	£16.99	https://www.ebay.co.uk/itm/186317956790

To view this discussion on the web, visit https://groups.google.com/d/msgid/york-hack-space/CAEopcLeCrwmw6v%2BHPp2DyVDns3%3DW5sY1o0pf_78U2VOY%3D1_J%3DQ%40mail.gmail.com.

[Gavin Atkinson]

Thanks.

Couple of questions:

- Are we sure the PSU won't attract import duty, coming direct from China? VAT shouldn't be an issue I don't think, but should also be confirmed

- There's no parts on the shopping list relating to the laser path. Given tube beams are usually much wider than RF lasers, are we sure nothing on the path will be in the way?

If this plan as-is doesn't work, do we have a feel for what issues we may hit and therefore how much extra funding may be needed?

Gavin 

To view this discussion on the web, visit https://groups.google.com/d/msgid/york-hack-space/hPaJf9lL-ti7wEh6J-EGdKHQMztXn2NcLPw_aYIdMp1uLypVyjIi5F3WAJvTFLpn8RZTyaCRGTk3W4pWQEHcnc4ScBcxi6mmao6vz8RdF2E%3D%40lexbailey.me.

[John Cooper]

Good work on all the planning with this. Of the options the one where we keep the two separate and don't touch the k40 would be the option I'd support. Worth the extra to have them independent.

I have some questions but generally none that should get in the way of doing the above.

Will the new 60w be a big improvement to the current k40?

Do we need two laser cutters? They are quite bulky and jobs are normally quite quick. Would it be worth looking at selling the k40 and reclaiming the space?

I can't remember but does the big one have storage space under it? If not, does the new tube free up some space for that or trimming the bottom off? Might be a good time to do that before the tube goes in.

Last one is about the financing of this and other spends, we are loosing money at the moment if I understand things. With this, storage builds and new 3d printer will this leave us much in reserve? I don't know what is pulling in the new members but I'm not sure a second similar laser cutter is going to add much to that aspect. It might be that we can wait for this if other more critical things are demanding on the finances.

john

--
You received this message because you are subscribed to the Google Groups "York Hackspace" group.
To unsubscribe from this group and stop receiving emails from it, send an email to york-hack-spa...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/york-hack-space/CvJVibZE24uQRGP5yt7LrxOc8wK9DSPP34ZUkBVOBl7LOhsKb6x3AJOMZSTVVDCgU6GQnQKBue2vIBsmojQda-Wro6u3XfyTNzLtWPGmYLY%3D%40lexbailey.me.

--

John Cooper

[Lex Bailey]

I see some of these question have been asked and answered already in the discord, especially Gav's questions. duplicating here for completeness, and answering John's questions too:

The laser path is suitably wide for the new laser, there's lots of room available.

The power supply can probably be sourced without import duty, discussed in discord. Price will still be in that ballpark though.

As for problems we might face: there is only one issue we are _maybe_ anticipating. That is that the PWM from the controller might not be exactly right for the type of tube/power supply we're going for. If that proves to be a problem, then the electronics to convert the signal to the right form is cheap (<£10).

Other than that, it's still fundamentally just a laser beam going through the exact same path as the previous one, I'm not expecting any particularly difficult issues.

On "will 60W be a big improvement ... ?":

Yes! 50% better! :D

The K40 has a 40W tube, this will be a 60W tube, we should be able to do slightly thicker materials, but also cut the same materials faster. The cost difference between the 40 and 60W tubes is minimal, so I see this as an easy decision. I'm mainly excited for the increased bed size though, certainly this machine as a whole is far more capable than the K40.

Do we need two laser cutters?

Honestly, given the current usage pattern of the laser cutter: no. If we get this one working well, then the only reason to keep the K40 would be as a backup, or if anyone really needs the K40 workflow and can't move over to the GCC cutter. I suspect there won't be anything that the K40 can do that the GCC can't. The only caveats might be that the software for the GCC is less sophisticated, but with some effort we can fix that. I think we certainly want the GCC working, once it's up and running and people are happy with it, we can then ask the question of "shall we get rid of the K40?". Having said that, I do have an annecdote from a larger hackspace: Makespace Cambridge got a very capable laser cutter and quickly found it became the most popular machine. They have a lot more members than us, but we should expect to grow a bit now we have the bigger space. Makespace had to buy a second machine to reduce the queue times for the laser cutter, and even after that I remember queueing to get on one of the machines for a few hours. Having two machines might be really handy in the future if our membership explodes.

Is there storage space under the GCC laser?

Yes, there's doors on the front with some storage inside. Currently there's the dust cover, cables, and various parts that are no longer needed. That cabinet will house the air pump and possibly the cooler (if it fits and the air flow is sufficient).

I don't think it's feasible to increase the storage space. To do that would require cutting through a large metal plate (steel?) to create an opening from front to back. This would open right in to the space where the tube is going to go. Mounting the tube up higher will not be easy either. The optical path is mostly rigid tube that is currently neatly mounted in a suitable place for the new tube to go. So, this operation might compromise the integrity of the machine's chasis, and wouldn't get us much extra space anyway.

As for John's finance question, I'll have to defer to Gav, but it is true that we can put off this spend for a while if we need to. We already have a working laser cutter. I know that two people currently at the space are excited for the larger machine, so they can cut larger workpieces, and perhaps it will attract more members who also want to do large laser cut projects. I don't mind defering the purchase if we have to, but I certainly would make use of the larger area.

Some ideas regarding finanace: We could encourage users of the large laser cutter to make an optional donation per use for a while to recover some of the cost of getting it working? I don't know how effective that would be, but maybe worth a go. I know other hackspaces have a pledge system, where people can put money towards a specific spending goal. If we can't afford this at the moment, but could maybe do a pledge drive to raise some or all of the cost, I'd be willing to give that a go.

To view this discussion on the web, visit https://groups.google.com/d/msgid/york-hack-space/CAKT6ECqv7aGR%3DYYrS-h5LnxXSnK1yBVEz4PEubF0OZ%3DMesXp2Q%40mail.gmail.com.

[Lex Bailey]

While the required 48 hours has now passed, and people are clearly in favour of the £690 option, I would like to get a bit more feedback before declaring that we've committed to this, since it is a very large spend at a time when we are slowly losing money.

I want to know how much use the laser cutter would get, and people's thoughts on how the repair should be funded.

I have created a google form to get these answers, please fill it in if you can. Even if you are not a member, you can still fill this form in. If you're going to join to use the laser cutter then we'd love to know that.

https://docs.google.com/forms/d/e/1FAIpQLSeANX-JHXT_pC8aSovhcs440O4fl0ug9inL3WI6vX-sbBV5VQ/viewform?usp=sf_link

This will decide if we: just go for it, wait until finances are more stable, or try to get donations for the repair.

Thanks!

[Lex Bailey]

Thanks to the 7 people who replied to the google form

Everyone that responded wants the big GCC laser cutter working, and wants to use it. There is significant interest from members in putting donations towards the laser cutter repair. of the 7 replies, 5 of them thought we should spend the money now, and 2 of them expressed no strong opinion on spending now or deferring. Nobody is against spending the money now.

We asked if people would be willing to donate to the laser repair fund. The total amount that people said on the form that they could pledge was about £420, with some others maybe being able to donate later. Most of this is from one very generous donation pledge, thank you John R :)

This means that the £690 option will only require spending about £270 from hackspace funds. As for the proposal of a per-use fee for the cutter: 4/7 people would be happy to pay a small fee per use. 4/7 respondents thought it should be an optional donation, not a mandatory fee. Given the large amount of donations that are already pledged, I don't see any need to recommend a per-use donation once the cutter is fixed. We should be able to have this machine be treated the same as any other tool in the space, in that access to it is included in everyone's membership. I see this as the ideal outcome. And just to make sure it's clear: there will be equal access to the laser cutter for all members, there is no priority given to donors, don't worry.

From what I have discussed with Gav, as treasurer, I'm confident that (with the donations to the laser repair fund) we can go ahead with the spending for the repair without putting the hackspace in a tricky financial position.

Hooray!

We're going to start ordering parts now.

To those that pledged donations: thank you very much, please send the donations by bank transfer if you can, I think all of you have the details. There is also the donation page on the website if you need that instead, but using that incurs a transaction fee, so your donation will be slightly less if you go through that method.

Thanks!

Lex