shadowing when engraving problem

[Mike]

Hi Guys I need some help please

I do allot of engraving on laminates, I always engrave in dual directions as it saves time, yesterday I tried to engrave a job and the there is obviously some misalignment happening as the engraving in one direction does not line up with the engraving from the other direction , the effect is the word become two works slightly apart, i.e. shadow.

The head runs on a timing belt, so I thought that maybe that was loose, I have tightened it slightly but that hasn’t helped much, my other thoughts are
the cog is slipping on the stepper motor… nightmare to check
or the belt has worn out in that area because I use it there the most…another nightmare.

Anybody else experienced something similar, I am having to run the machine with the dual direction turned off and the jobs are taking hours instead of minutes.

Thanks

Mike

[Spooky]

Hiya Mike,

Which model of machine is it?

[Mike]

Its a LS3060 plus laser engraver

I have manually moved the head and can't see any slack movement in the spocket attached to the motor. It's only 8 months old so I wouldnt have thought the belt would have worn out by now.

the head runs up and down on 4 nylon rollers, they dont look worn but the bearing inside might be looser, thik I may look at ugrading that sliding system, what do the bigger machines use?

[Spooky]

Hiya Mike,

The bigger machines use steel hardened rollers ,the plastic red blocks on the carriageways are wipers, the bearings are inside of those. hummm....how about lubrication? good quality silicon oil will prevent drag on the bearings and drag can cause just the problems you are having.

Belts do wear but the problems you have described suggest backlash,there are only limited things that can cause that so we better eliminate the simple ones first.

best wishes

Dave

[Mike]

I lubricate and clean that railing quite often so I dont think its that, I am going to investigate a little more just now.

Thanks for your help

[Mike]

Ok I have some improvement, I have tightened the timing belt and it has improved it significantly, now how tight can I make it before I start to damage the drive?

I think I will need to tighten the drive belt for the other direction too, not sure how to reach that though?

[Spooky]

bit of string kind of answer Mike, mine are at around 3.3lb of draw but I have a lot longer bedways so the same won't apply.

Maybe a bit at a time until the problem disappears OR maybe better would be to replace the belts with new ones (they are cheap) it may not be down to the stretch of the belt but to wear on the teeth, tightening them will mask the problem but may well overload the servo bearings.

I'd recommend new belts to be honest.

best wishes

Dave

[Mike]

Thanks Spooky thats probably good advise.

[Mike]

Just an update on this, I have pretty much solved the problem, the cause was the looseness of the laser head running up and down the cross bar

This machine has nylon rollers, which guide it up and down the bar, for whatever reason these were allowing some twist in the head as it moved back and forth, there is no proper way that I can see to tighten them against the bar, but I did manage to sort it out by changing the height of one of the rollers.

Need to speak to Chris about it to see if there is a better way to sort it. But the ghosting was gone last night.