Rotary Epilog Sizing Issue

[Chris J Anderson]

Hi to All,

I have an issue with a rotary engraving job in my Epilog Helix.
I use it regularly with no problems.

I have a job which will become regular, engraving wooden pen blanks for a pen maker.

Because of the design of the rotary kit in an Epilog, I can't fit an item as small as a (say ½ inch diameter) pen blank in the jig, as the laser head will hit the rotary parts.

I was thinking of making a jig, with wheels each end the same diameter as the rotary drive rollers (say they're about 3 inches), and then run a threaded rod through the middle to hold the pen blank in the middle, and have the rollers full distance apart, about 18 inches.
This would then give the laser head clearance if I centred the job in the middle.

My problem is how would I correctly calculate the page height in Corel (which is normally set to the job circumference).

I have tried many times to think about this, I can't get my head around it.

Worst case example is, I would have a design going all the way around the pen, wanting it to line up without seeing the join, so it would need to be very precise. (I know this is pushing it).

So assuming the end wheels are 75mm diameter, same as the epilog drive wheels, and the job is 13mm diameter, how would I calculate the correct page height ?

So I'm engraving on to a 40.8mm circumference pen blank, but driving a 235.6mm wheel on the end.

Could it be as simple as just stretching the design for the pen to match the circumference of the 75mm drive wheels ?


Sorry if this isn't clear, its hard enough to think about, let alone explain...

Cheers,
Chris

[Glen Monaghan]

If memory serves correctly, the Epilog rotary device works 1:1 so if you want to engrave around a 4" circumference, your design is 4" high. So, by positioning your X mm circumference pen blank in a 235.6 mm circumference jig, you'll get one complete pen rotation for each complete jig rotation and, consequently, your design should be 235.6 mm high. Note that the result is a squeezing of the design onto a much smaller space, which could significantly impact your power and dpi settings to avoid overburning the pen blank. That is, what you are setting up to print over 235.6 mm is getting squeezed into just 40.8 mm on the pen blank, about 1/6th the space so you could engrave at 100dpi and have about 600dpi on the pen blank. Likewise, you'd be engraving the blank about 6 times slower than the speed you set so you'd need to increase your speed and/or lower your power from whatever you'd use if you weren't using a jig.

[Chris J Anderson]

Thanks Glen,
I hadn't thought of that issue, and as the blanks are mostly wood, yes it would then be way overpowered.

Might be best for me to make a long jig around the same diameter as the pen blanks.

Thanks heaps for pointing that out...

[Kit Dumph]

Chris, have you tried calling the factory? Can't be the first one with pen engraving problems on an epilog? They might have a simple solution...

[Chris J Anderson]

Cheers Kit, I might email them, will post here if anything worthwhile results...

[Kev Williams]

Likewise, you'd be engraving the blank about 6 times slower than the speed you set so you'd need to increase your speed and/or lower your power from whatever you'd use if you weren't using a jig.

If you set the output at 100 lines per inch to equal 600 engraved lines per inch, it will engrave exactly the same speed as it would at a "regular" 600 lines per inch. And if 600 is too much resolution, 75 equals 450, and 50 equals 300 (assuming your machine will output those resolutions).

As for calculating the difference to make the start and end points identical, trial and error works great- Estimate the difference, get a sacrificial test pen, and engrave a short line at the top and bottom edge of the layout. Chances are they won't line up, just be sure to make note if the last line overruns the first line, or shorts it. Adjust as necessary, run it again, repeat until your first and last marks are dead-on. Even WITH good calculations, you'll need to tweak it anyway.

[Mike Null]

I bought dowels to use for my testing when doing pens.

[Real Mercier]

When I do pens on the rotary device, I ask pen makers to bring me the blanks before they assemble them and I use the pen mandrel to mount the blanks on the rotary. I also ask them to bring their bushings for the madrel also. I have some but not all. Thsi works well for me.

Real Mercier

[Kim Vellore]

On a test piece just draw a slightly sloped line with horizontal markers you will know the starting and ending points from it

[AL Ursich]

On a test piece just draw a slightly sloped line with horizontal markers you will know the starting and ending points from it

That was my answer too... Just mark a ruler on the pen at a angle so it get the distance. Match the lines on the pen to your Corel drawing and your done. I would use Grid Lines top and bottom.

[Chris J Anderson]

Thanks for the great replies people, Plenty of nice ideas there that I will be putting to use...

Many Thanks...
Chris

[Martin Boekers]

Chris, since you working with pen blanks... There are many styles out there doing inlays, here is some info on making an indexer
you might find interesting...

https://www.epiloglaser.com/how-it-w...haan-woods.htm

[Chris J Anderson]

Thank you Martin

[Bob McGinn]

Contact Epilog direct - they have had a 3-Jaw Chuck rotary for several years.

[Glen Monaghan]

Contact Epilog direct - they have had a 3-Jaw Chuck rotary for several years.

Not for their "classic" line of mini's and helix's