Explorer/Mercury Slanted Edge Problem Part 2

[JB Lynn]

Hello :)

Hope it's OK to start a new thread on this? Following Rodne Gold's g-r-e-a-t advice I did eliminate several potential causes of our problems!

To recap, our questions relate to an early GCC Explorer I 38X20 30 Watt Laser. Problem appears when doing Vector cutting such as 1/8" engraver's plastic. Main symptom is the side profile of the cut items do NOT have straight sides, they seem to have a slant. It was pointed out earlier this MUST be an alignment problem, ex. 'slanted beam'? This does make sense, so we went about fine-tuning the alignment. While tape-burn testing, we now get a nearly perfectly overlapped burn at the head at the home, center and front right position :D We have also confirmed that our table is nearly PERFECTLY level at all points...btw, it should be as it now has NEW table screws, but that was a whole different story.

Our question is: What else could be causing this side profile 'slanted' cut? Any chance it could be an 'unsquare' rail system? Could a slightly loose 'Y' belt (front to back) cause it? One thing we have noticed as suspicious is that when sliding the whole X rail to either extreme front or back of machine (y movement), at the point where it stops, only one side of the rail actually makes contact with the fixed black rail while the other side is about 3/32" of an inch away? Could this indicate an untrue condition? If so, how is this adjusted? Maybe Y belts or loosening the whole rail system? BTW, the 3/32" inch difference reverses itself when the rail it pushed all the way to machine's back; ex. gap at front left when pulled front and gap's at back right when pushed to machine's rear.

Finally, Rodne mentioned a collimating/red pointer upgrade to Explorer Series II specs. Could you please give an idea of what parts were included in the upgrade and which parts were made redundant from the original design.

Sorry for the looooong post but we're confident this can be solved with the thoughtful insight found here :)

Regards, JB Lynn

[Shaddy Dedmore]

hmmmm. how much of a slant, and has this problem always been there?

For me, because the way a laser focuses to a point (and that point it usually the top of the piece), the laser then burns through and becomes unfocused... looking at a side view of a laser beam would make it look like an hourglass, with the center of the hourglass the focal point. This always leaves a little slant for me on the vectored edge. I haven't tried other focal points, but I believe a 1.5" focal point would be more slanted than a 2" or 4". With 4" being the straightest. That's why people have more luck with Inlay when they mirror cut the inlay, then when they rop it in, the reverse it, so the slants are complimentary.

Could this be the slant you're refering to? It also might have to do with the heating of the material and the flowing of the material to make the bottom have more material than the top. That's just a WAG though, haven't tested anything. along those lines. You could use only the amount of power needed to just cut through if that was the case, to minimise it.

That's all i got, normally I'm afraid to speak up if I don't know for sure, but I figure I could at least help stimulate a discussion, I'm sure someone out there has some answers.

Shaddy

[Rodne Gold]

Cut a square of 8mm pex and see how the edges slant in comparison to how it sat in the machine , if all edges slant the same way , it is still a question of alignment one way or another. You can sort of work out where the problem lies by looking at whats slanting. If the head was cocked in respect of the motion system , you would really only get slants on cutting in one axis. The explorer comes with a 2" lens std and beam divergence isnt enough to slant 1/8" (3mm) material to any extent.
The upgrade includes a whole new housing system for the optics , miror and red beam that now sits next to the tube. The original housing at the bottom + the laser source mounting plate + the collimator lens and red beam thing and its housing at the top of the firing tube are replaced by this. Read beam is now at the laser source , so is the beam expander and the path from the bottom is now clear of any other stuff barring the normal mirors. You get quite a lot of new stuff with the upgrade - IMHO $600 was quite cheap?
In fact we paid less than that , $300 each to do the upgrade cos the agent was about 1000 miles from us and he thought it was a 1 day affair to do all 3 , took one day to do one and he had to come back , hence the reduction in price. you have to do a full alignmnet after doing this. If your motion system had significant play , enough to cock the mechanism in diff directions when cutting , your engraving would be shocking.
As an aside , a good check of power is to see that you can cut 3mm pex at all points on the table with 100% power and 1.3-1.5% speed.
An easy test of alignment at all points of the table is to cut a square in 3mm pex at top left so it JUST cuts thru , move the head to all 4 corners and middle and do the same without autofocussing etc , if there are bad variances in cutting , then its not aligned. The beam should hit the centre of the lens at ALL points over the table. that Y bearing thing doesnt sound right , but I have no idea as how to correct it , perhaps the mnfgrs will help - get hold of GCC direct in this regard. It could be a factor , especially if the machine was rebuilt without jigs etc.

[JB Lynn]

Hello :)

Thanks to everyone for their help, especially Rodne and the time he's spent responding.

I did do Rodne's test to verify even power output accross the table and YES I can cut with consistent results accross the whole 38X20 area :)

However, still having the same slanted edge/mismatch origin problem. See photos for examples. Also, we think it's pretty strange that a perfect circle made in Corel cuts with such 'rough edges'! See the photo and also notice it's start/stop offset problems? BTW, to eliminate any Vector table irregularity, the circles shown were cut directly on the machine's table!

Keep in mind we're getting these results with a nearly perfectly overlapped burn result at the head when doing a tape/burn test. Also, VERY level table.

Desperate for any help or suggestions? Are you still confident the Explorer II collimator/beam widener will probably fix this mess?

Thanks Again, JB Lynn

[Dave Rawn]

It looks like you have a loose belt pulley or a loose drive connection on your xy drives. Take the approiate size allen wrench and check the tightness of all the connections in your xy drives and pulleys.

[Rodne Gold]

The poor quality of circle is definately to do with some problem with the bearings , belts , x or y motor or all of them.
What concerns me is that the machine was rebuilt. We have had bad cuts when our X motor has gone or is going - the X motors , cos of speed , go first. We also replaced all our X rails and bearings cos we didnt know the bearing needed grease , we just lubed the rails and the bearing got dry.
Belts need to be "tight" , my dealer did say something some time ago about "tuning" the Y belts tension in some way.
It still doesnt really explain the slant , but if the motion system and bearing assy arent up to snuf , its not going to help going any further until it is 100%
Do you have a GCC tech near you , or it might be worth while to fly a guy in for a day to set it up 100%.