In response to the concern about rising electricity prices, I installed a power meter on the laser cutter on 27th August 2022. The power meter covers everything powered from the back panel of the laser cutter, including the cutter itself, chiller unit, air assist and extractor fan.
From 27th August to today (25th September), 29 days, the laser cutter has used 27.98kWh of electricity according to the meter. At our new rate of 52p per kWh as of 1st September 2022, this is £14.55 of electricity.
Our log book records 286 minutes of usage over that period. If charged at our lower rate of £5 per hour, that means we should have taken £23.83 in payments; enough to cover the electricity, but that means most of our revenue for the laser is being spent on electricity, and not much is left over for maintenance.
I also recorded the instantaneous use while using the laser cutter on 27th August.
idle: 27W
Idle with extraction fan: 236W
Idle with chiller: 103W
Idle with fan and chiller: 313W
With all systems on, laser active at 100% power: 754W
The maximum power usage multiplied by our logged usage time accounts for just 3kWh of those 28kWh of total usage. The idle power alone over the 29 days would be 18.8kWh of electricity. There will be some extra power usage outside the logged time because the extraction fan and chiller must stay on for some time after the actual cut. We should also account for some unrecorded or under-recorded use time. Those considered, however, it seems clear that the standby energy usage is one of the biggest problems. It’s also (IMO) a relatively easy thing to fix; I’ll follow up with a suggestion to reduce that soon.
My thoughts would be the chiller being left on by accident, or perhaps the control board leaving the steppers energised instead of having a sleep period.
Sorry not about the current thread, but unsure how else to contact you. You gave me my induction on the laser cutter, for which I am most grateful. I want to do some cutting on my own, but would feel better if you were there. When are you going to be in? I will try to be in at the same time? Cheers.
I have no immediate plans to be in the hackspace, but there are plenty of other users and trainers who should be able to help out.
For future reference, if you’re using the web front end for this forum, clicking on a user’s name should give you an option to directly message them rather than posting in a thread.
Hey everyone, I want to run through some numbers for the laser cutter and I’d appreciate if anyone wants to peer review them to check they stack up/make sense.
In the particular 29 days of recorded energy usage above, the laser cutter sat idle drawing 27W which equates to 18.8kWh which cost £9.78 in electricity. The laser team are installing a cutoff switch to remove this ongoing cost so one aspect to consider is the ongoing costs once this is operational.
The remaining electricity used in those 29 days was 9.18kWh which cost £4.77 split over 4.766 hours of recorded usage. This is all based on our current rate of 52p/kWh. There’s a number of assumptions and not all info might be 100% accurate, but it’s suggesting approximately £1 of electricity used for every hour of laser cutting.
So of the £5/h that we charge members to use the laser cutter, £1 goes on electricity and £4 is left for maintenance (once the isolation switch is added). The £1/10mins rate is appropriate since the chiller and fans will run for a bit longer etc so this rate is also likely to generate approx £4 for maintenance per hour.
Looking back, if the cost of electricity is £0.52/kWh and the laser cutter draws 27W when idle, if no one used it over the course of a month, it would cost the space a tenner. After 2.5h of use, the space would be net zero but also with no money left over for maintenance even though there’d been 2.5h of usage. So whether our current laser cutter has generated any profit or made a loss up to this point is very much dependant on how much it was used. This applies too when electricity was cheaper, obviously favouring less of a loss or more of a profit.
The laser is heavily used. Significant monies have been banked from it historically and ongoing. When I’ve banked laser money it will have laser in the reference on the bank statements.
We haven’t been recording it exactly but that’s a welcome project if someone wants to own it.
There has never been a month where the laser isn’t used. The regular training requests and seeing people use it regularly tell us anecdotally that it’s very popular. On the rare occasion something goes wrong people are very keen to see it repaired and they voice these concerns.
The laser has absolutely generated a lot of income for the space. When you suggest it’s unclear the laser is profitable I think that’s wrong. Just nobody is volunteering to go back and count it all.
It’s never been questioned before. I would suggest checking the bank statements first then the log book if you genuinely doubt the money the laser generates for the space
The only thing with just counting cash, is it could come from material purchases (no idea if say laser plywood is sold at a profit) or from laser use.
But you’re right, just off the cash banked alone, usage seems decent, nevermind whatever the digital sales look like!
) if you need assistance.