Marking on Pens (diameter/focus question)

[Dave Hutton]

Hi All

Still in the research stages as to what I could make (and more importantly sell) with a laser.

I've had enquiries about pens and understand that they could be laser engraved, given the right material (wood, anodised aluminium - maybe plastics of some sort) Whilst having a look at various videos and suppliers websites I see them being engraved flat (not being turned) so my question is really is there a way or working out the actual area than can be engraved around the pen without loosing focus of the graphic/text?

I appreciate that a rotary attachment would allow a lot more area to be engraved but thats probably not practical for a big batch. I also note that pens are various thicknesses and some suppliers make a note of the 'engravable area' which would be a good guide, but I'm thinking more of a 'if it gets beyond X mm of the ideal focus it goes wrong' type of answers.

Looking at suppliers pricing it does though seem that I'd be just as well off getting bigger batches done by the supplier, but I have a couple of scenarios in mind where a customer might say "can you add some names to a dozen of so of those pens you usually supply with just our logo on?" so it would be nice to be able to offer that service, along with maybe a small range of pens that I easily personalise as one-offs.

I did have a look at the search results but couldn't find exactly what I was looking for , so apologies in advance if its been asked before.

DJ

[Jack Clague]

Hi Dave, if you know the style of pens you supply you can create a jig to hold them in place allowing you to engrave more than one at a time, engraving in a area down the length of them should be no issue as the variation in height will not make a huge difference, if you are going to be engraving far over the sides without a rotary then you need to know the depth of field for you particular lens, what size is your lens? or what lenses do you have available?

[Mike Null]

Dave

I run an engraving business so my answers may not be applicable if you are more of a hobbyist. I've found pen engraving to be unprofitable and now only do it for one old customer. That said, engraving around the circumference of the pen is tedious, slow, and often not adequately repeatable. Jack's suggestion of a jig is what most of us use if we're trying to do higher volumes. In my case I use a simple V grooved piece of wood with a stop for lateral positioning and I do one at a time. I also use an indexing gadget which allows me to rotate the pen to do more than one line of equally spaced type. (actually my customer made it and has it or I'd show you a picture)

[Dave Sheldrake]

D = Diameter of input laser beam from tube.
F = Focal length of the lens we are using.
W = Wavelength of the laser tubes beam.
DOF = Useful depth of field for a given optical set up.


The equation goes as follows:


DOF = 2.5 x W x (F/D) ^2


Once you have the DOF draw a circle of the diameter you have on the pen. From the midpoint of the top drop a line by the DOF distance, where it crosses the circumference is how much working area you have for each lens focal length.

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[Bert Kemp]

I take 2 1/4" or 3/8" wood dowels and cut them the length of the pens and glue them together. pens rest neatly in this.

322629Note for Junior taken with my junky cell phone cam:rolleyes:

[Dave Hutton]

Thanks for the replies chaps - no machine as yet so unsure about lens/focal lengths etc, but from what I gather the machine I'm looking at would be suitable- so I'm probably being a bit cautious/concerned before the event :-)

I've seen there is a jig template on laser bits site (plus you can buy the actual jig here in UK ! whoopee !) so I'd probably do that.

I'd agree Mike its not really profitable as the actual costs from a pen supplier without engraving is approx 20p each less than engraved, so thats not a great deal less than buying them done already - assuming the work is ok which I'm sure it will be then thats the way to go for orders over 50pcs. Then I can keep a few in stock for the odd ones which I'll charge a fair bit more than 20p for :-)

Ta

DJ

[Jeff Belany]

Don't spend $$ on a jig. Just take a piece of BB ply or acrylic or even matboard and cut rectangles the size of the pen. Doesn't take much to keep them in place. I don't have a rotary and have done hundreds of pens. There is a limit as to how much you can do in one pass but you can always rotate and do the other side.

Jeff in northern Wisconsin

[Roy Sanders]

Hi I turn pens I engraved the circumference in Celtic knots

[Bruce Volden]

Don't spend $$ on a jig. Just take a piece of BB ply or acrylic or even matboard and cut rectangles the size of the pen. Doesn't take much to keep them in place. I don't have a rotary and have done hundreds of pens. There is a limit as to how much you can do in one pass but you can always rotate and do the other side.

Jeff in northern Wisconsin

+1, save your funds for other "toys"!

Bruce