View Full Version : Why I've been asking if mopa's engrave deeper faster

Kev Williams
02-09-2017, 8:21 PM
Here's another Macgyver special holding jig-- hey, whatever works!

This is a seal mold a customer needed a part number in- normally I'd tool engrave this on the 3400 cylinder machine, because of its diameter and the welded-on handles and tabs there was always interference. I could've possibly rigged up a similar jig for one of the XT machines but it would have to be clamped down, hard, so it won't move. To laser etch, it just has to sit there and mind its own bidness. So, my HF motorcycle jack, couple of buckets, an old table leaf, an old weird clamp-on-a-board my dad made years ago (to hold 1-1/4" aluminum rod to be drilled), a piece of 2x4, an axle (the drill bit that drilled the hole ;) ), and a piece of 1x4 to prop it all up on the close-enough-for-me 30 angle needed and I was ready to go.

I ran 2 letters at a time, rotated the mold and lined up the next 2- here it's working on the 3rd pair of letters...

-finished product, which also shows some bad news... :( -
It turned out very nice, and I didn't get the best silly putty pressing but it does show I got 'er plenty deep enough...
But the bad news, notice some of the lettering shows shadows...

I thought maybe the jack dropped a snick, or the mold moved on the axle, but nope. This is same stupid goofing-up it did before...
Note the 5, and all else for that matter, other than the engraving is out of position and the 5 is shaped wrong (like it did before),
the engraving is fine. At 500mm/s it takes over a second to sweep these 3/16" tall letters from top to bottom.
If the part had moved, the hatch would've been abrutly interrupted-- but it's not...

this dash was the 'odd man out' in running 2 letters, so I did this by itself, and I watched it engrave since it went fast-
While I didn't notice it was engraving wrong, I DID notice that nothing moved during the engraving.
This dash missed 3 different times. And the 1 is skeewhompus shaped like the 5...

So now there's this to deal with again. After I noticed the mold, I ran the job in the same exact manner, just lots less power, on some aluminum to see if I could get it to repeat the issue.

HELL no. Perfect. 45 three-hatch passes followed by 10 more three-hatch passes, as I did the mold. Not one bobble...

On the plus side, I still have the brand new not opened yet scanhead Triumph sent me. With so many Chinese holidays and trade shows they're having, they never know when they'll be in to accept the shipment, so I still have it. I may end up sending them back the old one...

The ONLY thing off the wall that happened during all this, is I have to move the laser toward the edge of the table so I could get at the mold . I have it setting on a small 1x board, and as I was pulling the board to move the laser, I ended up pulling the board out from under the rear legs, and it 'thumped' down on the table. Not very hard, but just wondering if jostling the thing may have caused today's issue? I've assumed an iffy connection was the culprit, maybe it's still iffy... anyway, going to run more tests as I have a job coming next week that will eat 20 full hours of fiber time, can't have it messing up! Think I'll just put the new scan head on for good measure too...

David Somers
02-09-2017, 8:48 PM

Am just asking out of curiosity. Obviously don't have a fiber but have been following your adventures (and those of others) our of general interest.

Is your customer going to be put out by this? Is this the sort of fault that would cost you money either to replace the mold or a reduction in your payment for a less than pristine job?

What thoughts has Triumph had about what it going on?

Hoping this is not a biggie for your customer. And of course, interested in what you find the problem is.
Oh...by the way....by scan head I assume you mean that square head the laser coming out of? Had heard that called a galvo head but assume scan head means the same thing?

Fingers crossed! <grin>


John Lifer
02-09-2017, 9:51 PM
Kev will respond, but if thie is an injection mold for plastic parts, it looks way better than edm that was used 10 - 15 years ago. (Probably still used by some). As long as there are no undercuts and that would be nearly impossible with a laser, it should be fine

Scott Marquez
02-10-2017, 12:10 AM
Just order the new 50 watt fiber and move on. LOL
I hope the new scan head solves your problems, you have much more patience then me, if I have a piece of equipment that causes me frustration, I schedule it for replacement.
Good luck, Scott

Kev Williams
02-10-2017, 12:24 AM
This is a soft rubber seal mold, print calls out for .020" deep engraving, which normally is borderline extreme for plastic molding, but rubber doesn't take on the detail like plastic. So those shadows will never be noticed in the seal itself. I told them I could get .008 to .010" deep with the laser, they just said 'try for at least .010'... I'm actually pretty close to .015", so I'm happy. I'm the only guy around these parts that can (or will) engrave this kind of stuff so just getting it done at ALL is the most important, so they'll be happy too.

Had this been say, a plastic case mold for a bedbug trap with the company's logo engraved, then the laser's shenanigans would've likely fubar'd it. But in this case, I got lucky!

John brought up EDM, not long ago I/we were talking about EDM and I mentioned I had an old master and part, and I ran into it the other day while looking for something!
This is probably more than 25 years old, the copper is the master I engraved, and the steel stamp it produced via EDM. I got these back as they needed another one made, this one didn't have enough draft angle, and the cutter tool tip needed to be narrower...

views across the top-

Closeup shows what John referred to, the sides of the letters are quite mottled-
and you can see the reliefs are fairly narrow (too straight up & down, not enough angle) and the top edge of the stamp outlines are pretty fat, hard to push that into sheet metal!
I probably used a 22 tool angle on this one, tip width is around .015", second one I used a 30 tool with a .008" width tip. I still have that same tool set aside just for EDM masters!

-perfect fit! :D

Anyway, steel stamps are just one use for EDM'ing :)