@donkjr
C: 00.6
D: 00.5 - 00.6
@donkjr
Hi Don
Are you aware of a Silicone I can buy and safely use here in the uk ?
Was thinking of changing the tube back to the original one ?
@Domm434 @donkjr
Hi Joe / Don
I didn’t get any silicone with the machine so need to buy some. I’m in the uk - s this one ok ?
https://www.amazon.co.uk/Permatex-81724-Sensor-Safe-Silicone-Gasket/dp/B00TQ3GAA6
This one should do (note, it’s ‘neutral cure’)
http://www.wickes.co.uk/Wickes-Frame-Silicone-Sealant-White-310ml/p/243013
I suggested Dow 703 as it sounds like a Dow number and most of the chinese suppliers call it 703. But it seems Dow don’t make that - though ‘703 silicone’ will find plenty of suitable products.
What you need is ‘alkoxy based’ or ‘neutral cure’. NOT ‘acetoxy based’. Avoid anything with ‘acet’ in the name - it generates acetic acid while curing which will corrode the wire and pin
@Frank_Farrant it looks like your cathode is connected to the supply and ground correctly…
This seems like a bad tube although that is hard to believe.
@Frank_Farrant Here is one example of a user that had arc’ing as a result of a bad tube:
https://plus.google.com/106608075082031214915/posts/9LYvrYuCkMi
@donkjr thanks
Will this be ok as I can buy locally
Servisol Silicone Adhesive Sealant 75ml
Code: RE89W
@Frank_Farrant I think it will be ok, you can always replace it when we get you working.
At this point I would guess that nothing will stop this arc if the tube is open.
I use the blue stuff you linked to earlier. I have to check on the corrosive impact but I think that problem is well outside of your timeline.
BTW I found the Permatex Blue RTV at auto stores and in Wallmart.
@donkjr thanks Don.
I’ll try the original tube back in with the Servisol Silicone.
Since posting, the Chinese tech guy has said it’s ok to use.
Any idea how long I should wait before I try it ? 24 hours ?
I would recommend 24hrs.
What has the Chinese tech said about the current state of the problem…tube bad?
Are you getting warranty help from them.
@donkjr I bought this tube from Amazon seller almost £200 so it will be going back.
When the machine stopped working Chinese said tube but after I had ordered it they said to test the PS and then sent me a new PS.
I will put the original tube back in and follow the video about twisting the cables on and using Silicone.
Really hope it works.
Will look for a 2nd hand K40 as a spare as I’ve lost 100’s of orders.
Will let you know how it goes.
Thanks
@donkjr @artag
Hi. Getting somewhere.
Original tube back in and cables on yesterday. Tested it this morning and fires ok. Checked the mirrors and all looks good.
However, I’ve just gone to cut some 3mm mdf and Ply but it won’t cut anywhere near through it. More like a deep engrave.
Using all usual settings / height etc.
.
Does the new PS need some type of adjustment so it matched with % reading on the Amperemeter indicator ?
Thanks
Don covers this in depth at http://donsthings.blogspot.co.uk/2016/12/engraving-and-pwm-control.html but mostly with respect to a smoothie controller. It may also be relevant to the stock controller but I’m not sure of the setup. Anyone know ?
I’ve used both digital and analog controls on laser cutters and I feel more comfortable when there’s an actual milliameter present. The digital dials seem to be just % of max PWM output and don’t really tell you what the laser is doing.
@artag @donkjr
I’ve only ever used the digital reading on my K40d and know as much about electronics / lasers, as a goldfish.
Anyone with a K40d had to change PS - did this affect the % power needed ?
Any tests I can do ?
@Frank_Farrant the LPS should not need adjustment. I know you have checked the mirrors but I would suspect an optical alignment problem. With all the tube jocky-ing its likely your laser tube is out of alignment.
I would walk through an alignment again insuring that the tube is parallel to the gantry and the beam is going straight through the cutting head and not hitting anything.
The reason I do not have a digital panel is that the actual current from the tube is the only we have as to what the tube is actually doing.
@donkjr I think some PSUs have a gain adjustment that let you set the actual tube current that corresponds to 100% on the digital meter. Or there may be a setting somewhere that does the same thing.
I recall a PSU on our first hackspace laser that was set too high, so 100% on the panel was more than the max for the 50W tube. We think this contributed to a short life of the tube, though most tubes we tried got far less life than advertised, even after adjusting this.
Unfortunately, even if you can find the adjustment, you need a real meter in the tube circuit to set it up correctly.
@artag yes there is an adjustment pot but its not an adjustment that I think would change @Frank_Farrant power that much and there is no good way to know optical power vs current.