Slanted Edge Cut Problem w/GCC Explorer

[JB Lynn]

Hello :)

Having a problem with our 38X20 GCC Explorer 30 Watt machine.

When vector cutting 1/8" engraver's plastic the cut pieces don't have straight (top to bottom) edges...they are on a slant! Additionally, there's a tendency for the start/stop point of each indivual piece to NOT line up? For example, the finished piece won't necessarily break free of the scrap because it will still be connected by the misalignment caused from different beginning and end point?

I have confirmed our artwork is fine since these same pieces cut straight on our older New Hermes laser.

Is this an alignment problem? This machine has 4 mirrors (4th mirror is fixed non-adjustable on cutting head above the focus lens). I was told that adjustment of mirror #1 (which creates 90 degree upward path to mirror #2) is the way to correct this? Any experiences? Also have heard the way to fix this is to create a near-overlap burn (with maskig tape) at origin and right front of machine? This seems to be nearly impossible (at least with mirror #1 adjustments) as the beam path wants to always 'naturally' differ between origin and it's extreme counterpart? We can keep the beam with the focus chamber, it just wants to gradually stray from the burn spot at the origin...of course all of this refers to results while doing 'burn test' with masking tape?

VERY interested in hearing from other GCC Explorer users that may have an answer to this? BTW, we are ALMOST 100% certain this is only an adjustment concern as the machine has MANY new parts that all seems to work fine independently.

Sorry for the looooooong post, just need to get straight cuts that end where they started :)

Regards, JBL

[Rodne Gold]

It's an alignment problem , essentially the beam is NOT hitting the centre of the lens and is being deflected to a slant.
I'm not sure which model you have , but the Original explorers with the red beam in the collimater at the top of the firing tube near the top of the machine are VERY difficult to align , there was an upgrade to that and a further upgrade to the explorer II , we upgraded our Original explorers to Explorer II status which puts a beam expander and the red beam right at the source (I think its about $600 - well worth it) , the beam expander stops a lot of alignment issues.Laserpro USA has a nice alignment document for the mercury that applys to the Explorer and Im sure my Explorer manual had one too. At the end of it all , the first step is to get a central burning mark at the hole at the top left corner and thius should be aligned with the red beam , you take things from there. Alignment is tricky as its in 3d space and at one point on the table its spot on but as you move the head it changes. Our first one was a nightmare , thereafter it gets easier. If you have a tech near you , far better to get them to do it.
What is more worrying is the "step" , considering the alignment at the start point shoud be IDENTICAL to the end point on a cut , there should be no step unless the motion system (motor or shaft encoder) is faulty or the piece moves or there is a loose mirror or lens. The shaft encoders on the older models had a housing that was not sealed and dust can get in , to remove the motors and the housings of the encoders and to clean them with a dry soft brush is pretty easy. Replace the housing and put some masking tape over the "gaps"
Check the motion system and belts for play and check you have all the mirrors tight and nothing is loose on any of the housings.
Check your lens is in straight and is not cocked in its housing.
Also check your table is exactly level to your head , easy to do by just raising the table to leave a teeny gap tween the focus probe and it , and move the head around to see the gap doesnt change. also check that the vector cutting table isnt warped (if you are using it) - do it more or less the same way.

[Michael McDuffie]

Can't help with the beam alignment but my Epilog legend came with the belts way too loose. It would cut egg shaped circles and leave a bit at the top (or where ever the cut started and stopped).
I began tightening belts until I got true circles, didn't take much.

Michael

[Frank Ross]

My Explorer did the same thing after a mirror and lens cleaning session. On the Explorer, the #4 mirror is a very tight fit. Remove mirror 4, then replace it making sure that it is seated in the bottom and back of the holder. Tighten the hold-down screw firmly. Check the hold-down screws on the other mirrors.

[JB Lynn]

Thanks to everyone for responding :) Have a few more questions for Rodne as he seems to be on to something here?

Rodne, YES, we do apparently have an older Explorer (made late 2002). The collimating lens is indeed in a box with the red pointer and red pointer mirror all directly below Mirror #2.

Sounds like the upgrade to an Explorer II design will likely be our solution? If we opt for this, does the collimating lens, red pointer and red pointer mirror reside in a new location, perhaps near the back bottom of the machine near the tube? Any suggestions for a photo of this setup?

A few other observations: When doing tape burn test directly on the tube outlet the burn is NOT exactly in the center, is this normal? Also, after bouncing off mirror #1 (and making a 90 degree upward turn) the beam must travel through the first section of pipe. A tape burn test on this end of the pipe shows a burn at about the 8 O'clock position, nowhere near the center? Can you picture this, is this correct? We was just thinking that at this point it seems the beam should be VERY near the center of the pipe, then again, is there any chance the pipe (which is being used a reference) is not straight?

Finally, in our current collimating lens and it's box (early Explorer style), it seems that our red pointer mirror covers some of the collimating lens, is this normal?

Sorry for ALL of the questions, but you have been EXtremely helpful and perhaps this info will solve this nagging problem. Where did you buy your Explorer II style collimating upgrade?

Regards, JB Lynn

PS: BTW, this machine, although 2.5 years seems to have been used VERY little. We bought it second-hand and it was literally in pieces! I am starting to think the original owner had the same problems and in trying to fix it probably lost/damaged many parts which have all since been replaced by us...hence this must solely be an adjustment/collimating upgrade problem?

[Rodne Gold]

The new beam expander is right next to the outlet of the tube as is the red beam and mirrors , its a far better option then the collimator which is now removed and discarded the whole expander assembly replaces it , I dont have a pic of it. Its all at the bottom of the firing tube coming up to the top of the machine.
It seemed a bargain to me for $600 (from Gcc) as there was a lot of hardware and new lenses and mirrors involved. Apart from that , check your power supply , Gcc did upgrade ours free when there was some issue with it being slightly underpowered. There is also a small upgrade for your existing collimator to make removal of the lens easier for cleaning (it has to be cleaned regularily, Prior to this it was very fiddly to remove the lens and occasionally disturbed the red beam pointer mirror.
The burn off centre from the source is normal , however it is vital to adjust the burn and red pointer to exit dead centre out the firing tube top , otherwise alignement is almost impossible , In fact all burns need to be dead centre. (the new beam expander lessens power drop off across the table) the pipe is not normally off centre or not straight , in fact it really is just a sort of dust guard/protection , you can remove the tube if you wish
I dont quite know what other purpose it serves?
The red beam mirror shouldnt cover a lens , as I said , the act of cleaning the collimation lens often allows the mirror to slide down , hence the GCC fix.
It cant be obscuring the lens to the laser as if it was , you would have no beam emerging. The Explorer II has some other components as well , like a built in light , a new gear to go on the shafts of x and y motors and some other stuff I didnt do.

[Matty McQuilkin]

Had same problem with my Mercury.

The table was out of alignment, checked all four corners with focus tool.

realiged and corrected table level. no more slant when vector cuting.