X,Y home position

[Keith Colson]

I am trying to do some really accurate cutting by placing rectangular objects right up against the rulers and use the 0,0 as my reference. I have found that my laser is out by 3.7mm in x and 3.5mm in y using my measurement microscope.

Is there a simple way to calibrate the 0,0 position on the my VLS6.60 ? It must be something obvious I am missing.

Cheers
Keith

[Dan Hintz]

Loosen the rulers and readjust them to match up with your (0,0) point.

[Mike Null]

Isn't there a way within the software to do that--such as positioning the red dot pointer at 0-0 then setting home position to that point?

[Scott Shepherd]

I don't recall there being anything in the control panel settings but I could be wrong. A quick look around and I didn't see it. Two things to do, one is what Dan said, and just to simply it, you take the rulers off, then put masking tape or painters tape down where the rulers were. Then draw a line in your graphics software from X0,Y0 to the end of the X travel, then do it again and draw it to the bottom of the y travel, giving you 2 lines, essentially right where the rulers are located. Then laser through the tape, peel part of it away, revealing where the rules go, then butt the rulers against the tape and tighten them in place. Then your rulers will right to your machine. I've done it that way myself.

Second choice is to contact Universal. There is a hidden set of settings that I can't recall how to get to. I've only been in the screen 2 or 3 times over the years and the last time was probably 4 years ago, so I don't recall how to get there. There may be a way to adjust them in those settings, but I honestly don't know. I know I've never done it. It might not be possible, but I don't recall what's available to change. I accessed it via a tech support session and they told me the keys to hold down and what to type in and then I rebooted and it was over. Shoot them an email or give them a call. Maybe there's a way.

[Brian R Cain]

Dan is correct.

The easiest way to set the rulers is to first remove them, then lay down a strip of masking tape in each axis such that the centre line of the tape runs roughly along the zero line. Next take a cut through the tape along the zero position in each axis. Remove the sections of tape where the rulers need to be the butt the rulers up the remaining tape.

If you're using Corel, it doesn't allow you to print lines that are exactly along the 0,0 positions, you need to bring these inside the page slightly, say 0.05mm, but this will be as close as you will be able to set the rulers anyway, short of attaching a dial guage to the carriage and spending a lifetime tweaking the rulers to perfection.

[Keith Outten]

You can tape a piece of sheet material to the bed about a quarter inch from both rulers.
Then engrave a 1" square on the sheet at one inch from both rulers.
Then measure the actual distance from the engraved square to the rulers.
The distance you are off is the adjustment you make on the rulers.
You may have to do this a couple times to get the adjustment perfect.
.

[Bill Stearns]

Keith - and All ...
Not sure this info fits here, but maybe? I engrave quite 'few plates. (i.e. 3" x 1", 3-1/2" x 2", etc.) I used to place them in the upper/left corner against the rulers - was never accurate - off just enough to be noticeable - 'least to me. Plus, careful as I was, a plate, or two, would sometimes slip underneath the ruler a smidge! (Believe the Epilog techs once told me I might try adjusting what they called the "tickle". ? ) Anyway, what I've done now is: cut out plate shaped templates of the most popular sizes on a sheet of lasermax. (designed taking into consideration holes 'n clipped corners.) I use this template sheet with confidence, now, on the single plate jobs. I've cut additional templates allowing for multiple plates of the same sizes. Now, I don't cringe when someone asks for a plate to be engraved! (Hope this helps?)

Bill

[Kev Williams]

I'll add to the confusion...

What I do when I need a high-precision home position is just make a new home position...

tape some scrap strips of laminate to the table against the stops, inch wide or so, 12" long if that works-

Now run a cut 1/2" from the stops. (Me, I set the cuts at .503, which usually accounts for my laser's kerf nearly perfectly)

Remove the scrap, and test your new stops for accuracy. Put in a 1/2" top and left margin in Corel to serve as your new zero points. Make a couple of test vector cuts exactly 1" from the new "zero", then measure. If you measure say, 1.003, then move the appropriate margin out .003". If you measure .997, move the margin in .003", etc...

I build ski lift operator panels, which are machined from the reverse side because I have to mill bosses for blind studs. Since the panel is built in reverse on a "top-left" machine (my IS7000), this means the ENGRAVING 0/0 position is the top RIGHT side of the panel. Since the material is rarely identical in width from piece to piece, I use the above method to create a top-right zero point in my lasers. Once I determine the the new 0/0, the engraving always lines up perfectly with the machining.

[Henri Sallinen]

Keith - and All ...
Not sure this info fits here, but maybe? I engrave quite 'few plates. (i.e. 3" x 1", 3-1/2" x 2", etc.) I used to place them in the upper/left corner against the rulers - was never accurate - off just enough to be noticeable - 'least to me. Plus, careful as I was, a plate, or two, would sometimes slip underneath the ruler a smidge! (Believe the Epilog techs once told me I might try adjusting what they called the "tickle". ? ) Anyway, what I've done now is: cut out plate shaped templates of the most popular sizes on a sheet of lasermax. (designed taking into consideration holes 'n clipped corners.) I use this template sheet with confidence, now, on the single plate jobs. I've cut additional templates allowing for multiple plates of the same sizes. Now, I don't cringe when someone asks for a plate to be engraved! (Hope this helps?)

Bill

This is my way of doing it. Although it is good to have your home position where it should be at 0,0, but when I need to do something precisely in the middle etc. I cut a jig from corrugated cardboard that I have laying around quite much. This way I can be sure that my file is set dead on to my materials and everything cuts / engraves out just nicely.

It would not be a bad idea to calibrate your home position even if you would use the jig way.

[Keith Colson]

Thanks for all the feedback.

I have looked into the calibration methods and see that the Universal laser recommends cutting the tape on the engraving table and butting the rulers up against it. I can see two errors in this method, correct me if I am wrong. The laser cut width is about 400 microns in width. So doing this method precisely put your rulers in an extra 200 microns plus my unit will not cut on the 0 line, I need to step it to 0.03mm to cut. That's a 230 micron error stack before my eyes/microscope even come in to play. Its seems a bit silly, with my 3D printer I can just type in the offset and be done with it.

I am familiar with the nesting method where you cut a nest to place your part, this is currently what I do but it's extra work and another step I can make a mistake on, not to mention more cost for my customers. My Universal agent is finding out if there is a home tweak but he assures me that there is not but he is checking anyway.

If I get no luck with Universal I will try an idea I have. Having a precision laser cutter with ruler stops means I must get the rulers set to with in 10 microns or so for a fusspot like me to be satisfied. If I stick something in the laser I want it to cut exactly where I say within my careful placement error. My $500 home built 3D printer gets 10 to 20 microns accuracy so I expect my much more expensive laser to do the same.

The other thing that worries me, if I go to all the trouble of getting the rulers right on the money and then I adjust/maintain etc. I will have to go through the process again. So I need a quick repeatable process.

Cheers
Keith

[Scott Shepherd]

Having a precision laser cutter with ruler stops means I must get the rulers set to with in 10 microns or so for a fusspot like me to be satisfied. If I stick something in the laser I want it to cut exactly where I say within my careful placement error. My $500 home built 3D printer gets 10 to 20 microns accuracy so I expect my much more expensive laser to do the same.

Your expectations are way off here. 10 microns is .0003" of an inch. You can't hold .0003" of an inch with machines that lasers. The beam deflection and angle of the beam on various materials and thickness would make that tolerance impossible. I do think you are way off on your expectations. Moving the table up and down will completely change that too. The machines aren't aligned with the kind of accuracy you're talking about. You could get it dead right at Z0 and it could be off 100 microns at Z 1".

It's not ever going to be that accurate and it's going to move around over time as well. Not a lot, but it will move.

[Keith Colson]

I should have clarified my goal. The item I am working with is paper thin so Z does equal zero. I also only want the accuracy in the corner around the rulers. I want to align to about 10 microns or as good as I can get with the hope that I can stay well under 100 microns of error for some period of time, but starting with 230 microns by following the manual does not work for me. Yes, once the z is moved there are many other errors that stack up, table movement, beam angle etc. It is an interesting challenge and there is plenty for me to learn on this journey.

[Richard Rumancik]

I was very surprised when members suggested that the only way to move the origin on thsi machine was to move the rulers. But I pulled up a Universal manual and it seems like that is the prescribed way. It seems to be a very crude method - it is odd that they have not yet patched their firmware to allow you to enter actual measured offsets.

Given that moving rulers seems to be the only way to adjust home, I would go with Kev's method. I think this could be automated somewhat. Keep in mind that if you are cutting rectangular sheets you do not need to cut full (offset) rulers. You just need enough points to lock the material in uniquely. A tooling engineer would say this only needs three contact points (two on the long edge and one on the short edge.) You might elect to have a couple more if it works better for you. But lets say you just attach some small "coupons" to the table along the rulers in select locations. They should be screwed down or clamped. Then cut off each coupon to generate the required contact points. No real need to have full "rulers" if you are fixturing for rectuangular sheets.

You could probably do a setup like this in 5 or 10 minutes with no material cost.

When I think of nesting, it is for multiple parts. Each part is dropped into a pocket which has some clearance. This is fine if you don't care about exact position or rotation (eg name badges). But if you want better accuracy you want to fixture to edges or points (i.e. push the part into the corner, rather than let it float in a pocket.)

When the job is done you just remove and discard the coupons and install new ones for the nest run. You can get surprisingly good accuracy and repeatibility using this method.

[Scott Shepherd]

I should have clarified my goal. The item I am working with is paper thin so Z does equal zero. I also only want the accuracy in the corner around the rulers. I want to align to about 10 microns or as good as I can get with the hope that I can stay well under 100 microns of error for some period of time, but starting with 230 microns by following the manual does not work for me. Yes, once the z is moved there are many other errors that stack up, table movement, beam angle etc. It is an interesting challenge and there is plenty for me to learn on this journey.

That's not even remotely realistic on these type machines. I've seen machines move .010" from day to day. They just aren't that accurate. They position accurately, but they aren't dead on repeatable to the level you are talking about. Not by a long shot.

10 microns is splitting a human hair 10 times, and it's only one of those remaining pieces.

[Kev Williams]

This reminds me of a nightmare job I had, laser marking an anodized go/no-go jig used by a medical parts mfr. to measure needle tubes of various sizes. The jig measured roughly 14" x 7". There were nearly 100 vertical hash marks on this jig, .188" tall x .060" wide, and centered to within +/- .0015" of the dim spec. From dim input to the jig, about 10 marks were dead on, but less than half of all marks were within tolerance, the remaining marks were out slightly to over .030" in a couple of places. In the end I had to test run and measure each mark individually. I used painters tape for the mark, and my measuring equipment consisted of a 7x eyepiece and 12" Harbor Freight digital calipers. Once I was satisfied I etched the mark and moved to the next one. I definitely underbid THAT job!

Shepherd is correct, there's no high-precision to be expected from these machines. Belts stretch, belt teeth wear, focus distance changes, laser beam alignment is never perfect...