Laser maintenance

[Samwise Wilson]

Hello all,

The laser requires some maintenance, some parts are on the way.

You may of noticed the laser is taking longer than it used to to cut stuff. Hopefully this plan will fix that asap and then improve on the foundations of the laser.

Phase 1 will be to replace the focus lens (it is obliterated). It's a standard 20mm diameter one with 50.8mm focal length. This has been ordered and is shipping. No downtime will occur in this phase, but afterward the laser will be significantly stronger than it is now. (Faster cuts!)

Phase 2 will be to extract the gantry from the laser and check it is square. This also allows the first ever gantry cleaning (wheels, tightening etc) to take place. At the same time phase 3 can occur which is to test and replace all the steppers to be a standard (and known) performance. Extension to phase 3 may occur if some components are found to be sub optomal. (Like unround wheels / pulley). I expect a weekend of downtime once all parts have arrived.

Phase 4 will be a replacement of the tube if needed. - is someone able to find out the roundabout time tube has been used? Tube replacement shouldn't cause more downtime than a mirror alignment.

Phase 5 is upgrading the stepper drivers; only when we get good performance from phase 2/3. At this point we should have a known standard to document fully and work from for future maintenance, enabling software updates and tweaks to take place, with hardware issues ruled out.

Woo!

[Andy51055]

Any idea on timescale?

[Samwise Wilson]

About one China delivery.

[Tom Oldbury (Email #1)]

While we are working on upgrading the laser, can we replace the light in the unit so we can see cuts more clearly? (We could even stick some LED strips in there and connect it to an internal power rail, for better lighting.)

On Friday, 23 September 2016 23:20:56 UTC+1, Samwise Wilson wrote:

About one China delivery.

[Stanto]

For those not aware, this can range from 1 to 6 weeks on good deliveries.

[Samwise Wilson]

Good idea, I'll put a led strip in on Tues hopefully. Already have all the materials for a diffused strip.

[Samwise Wilson]

Light is done

https://goo.gl/photos/bcx2P5kPvnSaDHBJA

[Tom Oldbury (Email #1)]

Very nice.

[Samwise Wilson]

The new lens has arrived, I will get some time to look at the laser this Tuesday, it will need to be checked because it got tumbled in the move. Alongside that I will install the lens and possibly lay the foundation for workshop extraction, either temporary or budgeted. 

This might be a wise strategy for all items that could have been jiggled as they were moved.

[J C]

Yeah fairly sure there was something small metal and loose inside it when we put it on its side. May not be reattached to its base yet either. 

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[Tom Oldbury (Email #1)]

Fume extraction sounds great. Is there any way we can get later provision for fume extraction from the electronics bench, through the same system? I am thinking of a series of tubes but I don't know how expensive that will be to sort out.

[Samwise Wilson]

Will have to be planned out, atm strategy for me is to get laser up and better ASAP.

Extraction proper will need planning, should be able to manage a 60mm / 100mm diy PVC dust collection system pretty reasonably, no idea if this is suitable for electronics but I assume it may be and would eventually be closeby. 

Sounds simple but it needs things like grounding, CFM, yadda yadda.

[Phil Hutchinson]

Thats great to hear!

The Level base .. being not level... impacted one of my cuts the other night, made almost 0.25 mm difference from the left of machine to the right.

Im sure the move will have not made it better.

[Samwise Wilson]

0.25mm is probably well within the tolerance of its leveling system, its chain and spoke driving screws!

Are you sure you are giving the right terminology? 0.25mm out on Z on the laser shouldn't impact final cut anyways. (Its not possible to even focus it that well).

[Phil Hutchinson]

I was cutting 22mm Bearing Holes in Acrylic, any that were cut on the left of the bed where well fitting, anything cut further to the right were loose. 

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[Alex Silcock]

It definitely does impact the focus - I've had cuts fail because they cut through properly in some places, and less well in others. It must be out of tolerance much more than 0.25mm though on the Z axis for the focussing to be as much of a problem as it is.

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[Samwise Wilson]

Laser is probably out of alignment :( or its missing steps (i've noticed this behavior). Hopefully its TLC will resolve these issues. The new lens should help these issues alot because we wont be compensating for the poor lens surface. 

As a N.B.

I don't think the laser is physically capable of proper friction fits (0.0254mm tolerances) I think its theoretical max is 0.03mm.

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[Samwise Wilson]

@Alex

Failing to cut through towards one corner is generally mis-alignment of the mirrors not mis-leveling (also compounded by the lens surface). There isn't much we can do about the leveling mechanisms general slop and its far less critical than the alignment. 

On Wednesday, 19 October 2016 16:27:16 UTC+1, Alex wrote:

It definitely does impact the focus - I've had cuts fail because they cut through properly in some places, and less well in others. It must be out of tolerance much more than 0.25mm though on the Z axis for the focussing to be as much of a problem as it is.

On 19 October 2016 at 16:00, Phil Hutchinson <phil.d.h...@gmail.com> wrote:

I was cutting 22mm Bearing Holes in Acrylic, any that were cut on the left of the bed where well fitting, anything cut further to the right were loose. 

On Wed, Oct 19, 2016 at 10:10 AM, Samwise Wilson <s...@swwils.com> wrote:

0.25mm is probably well within the tolerance of its leveling system, its chain and spoke driving screws!

Are you sure you are giving the right terminology? 0.25mm out on Z on the laser shouldn't impact final cut anyways. (Its not possible to even focus it that well).

On Wednesday, 19 October 2016 00:50:52 UTC+1, Phil Hutchinson wrote:

Thats great to hear!

The Level base .. being not level... impacted one of my cuts the other night, made almost 0.25 mm difference from the left of machine to the right.

Im sure the move will have not made it better.

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[Samwise Wilson]

Its also worth noting that the tube, lens, mirrors, bearings and belts are all consumables in a laser cutter.

Documentation varies but lenses should be replaced as soon as the surface is even a little pitted, with a daily (8 hours use) check on it for cleaning - ours was totally obliterated. From what ive seen 3-6 months is a good lifetime for a lens for our current use; thats if it doesnt get obliterated (used when dirty).

[Paul Brook]

> Failing to cut through towards one corner is generally mis-alignment of the
> mirrors not mis-leveling (also compounded by the lens surface). There isn't
> much we can do about the leveling mechanisms general slop and its far less
> critical than the alignment.

A good test is to put a piece of 2-3mm thick mdf/acrylic under one wheel. If
the whole machine wobbles then we're good. If the machine distorts and all 4
wheels are still on the ground then this is likely to be a significant
problem. If the frame is not flat then you're never going to be able to align
the mirrors correctly.

While the base looks substantial, it is of square construction so provides
negligible additional rigidity. In fact the additional weight probably causes
the machine as a whole to distort more readily on an uneven surface. A bit of
cross bracing in the base might make a huge differece.

In the old space this problem was sufficiently bad that the lid often failed
to close properly. My guess is that while this is not the only problem, it
may exacerbate other problems.

Paul

[Samwise Wilson]

Today I dismantled all of the gantry and cleaned all the mechanics.

Machined a new pulley shaft as one was bent, also got the gantry head suitably on the gantry (only possible with a full disassembly).

Belts unlinked and mention matched, as well as the linear slide leveled with the idler on other side.

Motion is now smoother, especially in the Y direction.

Still need to level the machine itself, but the frame is now fine and in respect of the X axis.

Mirrors and lenses will need aligning and putting in, as well as the water and air, but the laser homes now as I put the whole assembly back in.

Next steps will be electrical. Putting phoenix connectors on the Laos board will make it much easier to use with external drivers and new steppers that are cabled rather than ribbon.

Mechanical upgrades could occur but need a think to improve on the designs in place at the moment - if we were to uptake this probably best to upgrade the whole thing.

[Samwise Wilson]

The laser is now leveled and has its water and air connected.

It needs better alignment! The tube itself has no adjustment so everything must be done after first mirror.

There is still no extraction so that would be a priority.

[J C]

Great progress. Thank you.

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[Samwise Wilson]

Had another set of work today on the laser.

Discovered that it really needs adjustable feet to get it properly level. When the machine is leveled we will then be able to get the Z axis level, which is vital for even focusing across the bed, at the moment it is close but needs doing properly.

I've also asked to grab a rough total hours on that tube, I get the feeling it's power output is really low even when in good alignment and given the crud that came out of the cooling loop it's not surprising!

We can tackle software when I'm back or of someone else wants too!

[Andy51055]

What are the plans for fume extraction? At least we can get on with sorting that out while Sam's away.
I'm beginning to suffer withdrawal symptoms.

[Aidan Dunbar]

First step is replace that crappy door I think. 

Extractor motor needs moving out of the laser case to free up room. Easiest to do without putting another hole in the laser is to rotate the laser 90 degrees so that the back is exposed to the passageway to the door. It will need levelling again (sorry Samwise) but if we take the chance to install some levelling screw feet then it'll be relatively straight forward.

On 9 November 2016 at 06:37, Andy51055 <you...@51055.com> wrote:

What are the plans for fume extraction? At least we can get on with sorting that out while Sam's away.
I'm beginning to suffer withdrawal symptoms.

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[Samwise Wilson]

Update on this, tube is putting out 42/46W.

Will measure after the mirrors soon to see if any loss is there.

After this I will book some software time, major updates to the visicut settings in github - the aim here would be to get all the settings right to make the presets in visicut to be speeds in mm/s like actual machines use. Because then materials will cut at a known speed with a known power, not an arbitrary %speed value.