[KenR60]

RedSail CO2 Laser
M900 with RECI 100w Tube
Auto Focus with Motorised Up and Down

Cutting MDF

I have tried changing the Power to 100% and the deepest it will cut is half a Millimetre ( or the thickness of a piece of paper )

I have aligned all Mirrors, just haven't done anything to the Auto Focus as I don't know where or what to touch there.

Any Help Much Appreciated

Ken Russell
Australia

[RogerClark]

Hi Ken

is this machine new or has it been running fine up until now?

Have you checked and cleaned the lens

can you manually check the focus is ok?

Do you have a current meter to measure the tube current (mA)

Cheers

Roger ( in Melbourne )

[pk7639]

Assuming that box is made up of single lines, there's no way it's in focus.
PK (Perth)

[KenR60]

Hello Roger, Thank You for your message. Yes the machine is Brand New, just gotten it.

1) No I never Cleaned the Len's as I thought they would be fine being Brand New, I did align them still.

2) Can you tell me ( or send me off to a page ) that explains how to Check the Focus? Again, being Auto Focus I was relying on this to be True.

3) Tube is a RECI 100w so I am guessing it should perform better then the cheaper Tubes?

I will read up on how to remove the Mirrors and Clean them tomorrow, just need some help of how I can Manually Focus the Laser? Don't have a Current Metre but if the Mirror and Focus corrections don't solve this I will find someone to test the current.

Thanks Again Roger, much Appreciated your questions and help

[KenR60]

Assuming that box is made up of single lines, there's no way it's in focus.
PK (Perth)

Thanks PK, I bought the machine with Auto Focus thinking it would be a lot faster and better then Manually trying to Focus, so my mistake in thinking I just needed to turn it on and "Bobs your Uncle" :-) Any Help you can give me on Manually Focusing would be appreciated, just incase Google and YouTube sends me off in another direction!!!!

[KenR60]

OK now I have learnt something more ... I found the "Auto Focus" Button ... I thought it was a DOT Key but its for adjusting the Autofocus. ... I adjusted the Focus and ran the Square again but still not much better. I will study this Video and others tomorrow and Manually Focus and test
https://www.youtube.com/watch?v=WnqnfIEzRLI

[KenR60]

Attachment 303646

This is the Auto Focus Part I Guess ... so if Auto Focus doesn't work then I will need to Manually Focus each Job or is there a method to correct the Auto Focus?

[Labmaster]

For finding the right focus point of your machine i would suggest to watch a couple of videos, especialy part 6.
If once the right focus lenght is detemined it should be fairly easy to modify the autofocus assembly to fit this lenght. (normaly by simply shifting the switchpoint up/down, there should be an option available to do so)

And btw, the imporant distance is not the nozzle end to the material, it's the focus lens (inside the head) to the material.

Chinese laser cutter tutorial -
part 2: https://www.youtube.com/watch?v=zF9nQHlvGkc
part 3: https://www.youtube.com/watch?v=SGD8BPZntxY
part 4: https://www.youtube.com/watch?v=fA1jM9hTk6s
part 5: https://www.youtube.com/watch?v=Zcze9B0BmpA
part 6: https://www.youtube.com/watch?v=PUdEUxJH2_o

There are a lot of other nice videos there, https://www.youtube.com/user/SarbarMultimedia/videos

best regards,
Walter

[KenR60]

Thank You Walter, very much appreciated, I will check these all out tomorrow!

[RogerClark]

Hi Ken

I only recently got my cheap eBay laser machine. The advert on eBay said it was 50W, but this is basically a lie, its probably more like 30W.

Anyway, I can cut 5mm MDF at max usable power (65 % power setting) at around 10 mm / sec

3mm MDF cuts at about 15mm / sec

3mm plywood is approx the same.


Can you post a link to what machine you bought. If its anything like the shoddy build quality of mine, you probably need to check a load of things.

Not that it makes a big difference, but lens tends to come fitted upside down. Convex side is supposed to be upwards.

BTW, are you somewhere hot in Aus, even in Melbourne I have to keep the cooling water for the laser a bit chilled. As ambient in my shed is around 22 deg at the moment.
As I didnt want to fork out $$ for a chiller unit, I'm currently freezing 1.5l bottles of water in my freezer, and putting them in the reservoir 10 mins before I run the laser, so that the reservoir temp drops down to about 15 deg.

But unless your water is very hot, i.e upper 20s, in the reservoir, I doubt that coolant temperature is an issue.

I presume you cleaned the lenses with isopropyl alcohol ( again I cant see how they could be dirty but they could be dusty)

BTW. when you check your lens, look down inside the nozzle and check for burning. If the beam is badly miss aligned you will burn inside your nozzle, and it eventually starts getting hot if you run it when miss aligned

.

[KenR60]

Hey Roger, here is what I bought Reci 100W Laser Tube CO2 USB Laser Engraving Cutting Machine 900 600mm | eBay

Anyone Reading this, WARNING *** DO NOT BUY off this ebay Seller. - LaserCheap ***** Buy Direct from RedSail instead.

Here is what I got for $5100,
100w Laser Cutter ( Was suppose to be 130w but Seller tried pulling a swifty on me and charged me $1000 extra but supplied only RECI 100w Tube
Motorised Up and Down Platform
Auto Focus
Honeycomb Mesh for the Platform
Red Dot

Seller made it sound like Customs and added expences on arrival would be very minimal. Was Free Delivery til it landed in Brisbane ( 20min away ) She said an Agent would ring me as soon as it landed, no one rang so by the time I started looking for it it was costing me $160 per day extra. Ended up getting it delivered and Customs clearance for $1700 ( $700 Delivery because of the weight of it ) I put it down to in-experience and next time I buy anything from China I will buy directly from the Company NOT some woman who knew everything I asked and gave me all the technical information that I now find nothing she said was true or correct, Only reason I bought this was to cut 12mm MDF in 1 pass which now with my 100w tube sounds like its not going to be used for any of my 12mm jobs :-(

[pk7639]

Alot of that is just experience gained.
We Import a lot of stuff from China and (from the little you have mentioned) it sounds like you were getting the correct responses from them.
No one overseas has any idea what our customs system is like. We always get them to send us the shipping documents to check before the goods leave (which I acknowledge isn't helpful if you don't know what to look for). Simillarly most companies we export to ask for our documents before they authorise us to ship.

The outrageous $1700 fee you got isn't from customs. It'll probably break down something like.
Local offloading fee $400
AQUIS inspection $100
Customs fee $100
Brokerage fee $100
(A dozen other fees that make no sense like dredging fee, infrastructure fee) $200


In short. It was the Australian freight handling system that screwed you.
You know how business people and politicians keep going on about reform on the waterfront?... Well now you know why! That industry takes a 10-25% cut of EVERYTHING that comes into this country.

As for $700 local delivery... well that's just stupid.

So, how do you avoid this?
You sort of can't, but you could probably have saved 40% of that $1700 by getting an FOB quote (Freight On Board) and then arranging sea freight through a local agency. (tip, get a few quotes) You just have to give them the port of origin, the cubic meterage of the goods and they will do the rest.

[RogerClark]

Hi Ken

I have one of these

High Promotion 50W CO2 Laser Engraving Cutting Machine Engraver Cutter 300x500 | eBay

The seller has been OK, apart from the usual over spec'ing of the laser tube.

I have no idea really what power the tube is. Its supposed to be 50W but there is a big official looking sticker on it by a company claiming to be called KH Laser , certifying the "Agreed Power" as 45W, I guess I could dispute the power with the eBay vendor, but in all honesty, I know that the machines sold on eBay as 50W are not 50W.

Mine just had a flat aluminium sheet as the cutting platform, so I'm in the process of removing that and fitting a central heating return air duct grill, which I bought for $50 for a local central heating company.

The machine has a motorised bed, but its manually operated, and at the moment I can't see any benefit of having a motorised bed or for autofocus.
Well, I guess the auto focus in theory saves time setting the height manually, but depending on what you want to cut, it can be beneficial to set the cut point in the middle of the depth of the wood etc, So as I'm adjusting this manually, I just set the distance manually using the spacer (provided) and then I motor the platform up 1 or 2 mm. I guess I should cut a stepped spacer tool out of acrylic in 1mm steps.

I'm not sure what "Red dot" is. Is it a better aiming system than the inaccurate red laser pointer that I have in my machine.?

[KenR60]

Thanks PK,

Here are my Test Squares for Idea Focus Measurement.
Power 85%
Speed 20mm/Sec

Setting on Auto Focus the 3mm MDF was 4mm below the Laser Bottom. From here I dropped the Table down to 7mm, 10mm, 12mm, 15mm, 18mm, 20mm between. To me I feel the 18mm is the Best Distance. I'm hoping now I can re-locate the Auto Focus to be 18mm off the top of the MDF.

Second Photo is pressing "Start" until the centre dropped out, it took 8 times to cut through 3mm which for a 100w still isn't correct so now I need to work on improving the Depth of the cut. I know this won't be correct BUT .... if the Platform was raised 3mm between each cut wouldn't it cut through in a lot less runs?

I have watched all Given Videos and learnt a lot, I didn't remove the Mirrors but used a Cotton Bud and cleaned each as shown in another Video I watched. Just a bit nervous removing the Mirrors and putting everything back together BUT ... if anyone thinks I still need to do that to see if it helps improve the cutting depth I will take on the Task. Otherwise any other hints on cutting through 3mm in 1 Pass?


Attachment 303744Attachment 303746

[RogerClark]

Ken

If you take your lens out you can work out the focal distance, but focusing a point source of light onto a sheet of paper and measure the distance.

I have LED low energy ceiling lights, which have 4 distinct LED's in them, and it was easy to focus them and measure the distance which transpired to be 51mm aka 2 inch focal length lens

But I presume your 20mm is the distance from your nozzle to the MDF which in my case is around 19mm.

If you have a 38mm lens, your nozzle will need to be only around 5mm from the wood, so I'd keep going closer and closer


I'd estimate that for a 100W you should be able to cut 3mm MDF in one pass at 25mm / sec or possibly even faster.

I can cut it at around 15mm/sec on my 40W laser.

With MDF you probably want to play with your Air Assist. I find that if you have a lot of air it just fans the flames and cuts worse than using minimum air.

[KenR60]

Ken

But I presume your 20mm is the distance from your nozzle to the MDF which in my case is around 19mm.

If you have a 38mm lens, your nozzle will need to be only around 5mm from the wood, so I'd keep going closer and closer.

Thanks Roger, I have moved my Autofocus to suit the 18mm between the Bottom of the Nozzle to the top of the Material so now I should be able to rely on the Auto Focus. As my example showed, 4mm away from the material created a much thicker line so Taking out the lens to find its Focal Distance shouldn't be necessary now? or Should it?

[pk7639]

How confident are you that your beam alignment is good? For us, (and we have a reci 100-120W tube in our larger machine), this is nearly always the cause of lost power.

[RogerClark]

Ken,

If you tried distances less than 18mm and it seemed to cause more smoke, i.e less defined line, than I'd make an educated guess to say you have a 51mm (50.8mm) lens in your machine (which is the same as mine)

I agree with PK. The most likely cause of your problem is now the alignment.

There are various postings on this forum about alignment, as its a common issue, in fact I thought I had reasonably good alignment on my machine but I was wrong, and I ended up having to do it again.

Turn the laser power on your control panel right down to perhaps 25%, so that when you pulse the laser you just get a really small dot and not a massive burn in the tape (or whatever you are using)

I would also recommend taking the lens out, because unless you do that, you have no way to know that the final mirror alignment is really correct.

Its not that hard to take the nozzle off, which contains the lens on my machine.

If you motor the bed up so that the nozzle almost touches the MDF, you can draw a line around the outside of the nozzle on the MDF, the lower the bed and remove the nozzle (and lens) then pulse the machine and see where the spot is.

Ideally it will be in the centre of the nozzle, but if its 5mm off I guess its OK, as the lens would refocus it to the centre, but ideally, I'd get it as close to centre without the lens

[KenR60]

OK, Thanks Everyone for your imput, something is working as I have managed to cut through 3mm in 1 pass ( YES YES YES YES )

OK got real Brave, took the Lens out that was closest to the bottom, so guessing the Focus Lens. it was only around 20mm round. Now what I did next made the difference. When I slide the Nozzle back I pushed it all the way up and tightened it there, I reduced the Power to 50% and Speed to 15, did the same 7 tests, 4mm between, 7mm, 10mm, 12mm, 15mm, 18mm and 20mm. and without realising the 15mm fell out so I was able to cut completely through using 50% Power at 15mm/Sec

Now Roger, is this what you were trying to explain to me ( and I didn't understand til now ) The Distance between the Last Mirror and the Lens is Very Important as this seems to have improved things.

Test on the Left is my original Test using 65% Power at 20mm/Sec, Test on the Right is 50% Power at 15mm/Sec

Attachment 303748

[KenR60]

AHhrrrrrrrrrr ... I did something Wrong ... I increased the Power to 65% thinking I should be able to cleanly cut through 3mm easier and instead I have a Wobble? Only thing I changed was the Power % unless something I did when taking the Lens out caused this later?

Also, the extra 15% Power did nothing, if I hold the board up to the light I can see the 15 Square ( 15mm between Nozzel and MDF ) almost cut through but not like the Previous Test where at 50% Power it fell out.