Is a ramp test required?

I’m setting up my new 80W Omtech with Auto Focus and I’m wondering if a ramp test is even required. The machine comes with a gauge that is 9.3mm (.366") thick and I know this is to set the focal length and when I do the ramp test it appears that the optimal length is the thickness of that gauge… just wondering if I’m out of my mind here or if this is a pointless step. Just seems redundant unless I’m forgetting something. If anyone has any thoughts, much appreciated.
Thanks

It is still a good idea to do a ramp test. Learn about what it does, and always question a measurement tool.

Thanks, yes I did watch a few videos, and I understand the function, just that when I check the distance (which is very tough to see exactly where it is sharpest) it seems to be around the thickness of the gauge. Figured if the manufacturer is including it with the product, must be the correct way to go. I guess it doesn’t hurt to just do a check here and there. Thanks

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As an example, for me and my 50w OMTECH, the focusing tool provided with the machine is 18mm. After doing a ramp test for the first time recently (I’ve owned the laser since April of last year), I discovered the optimal focal distance is 19.5mm. I modified one of the focus gauges I found in the Files section on the OMTECH Facebook group page to go to 20mm in half millimeter steps. Works for me.

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Kind of moot as you’ve already done the ramp test… You did this exactly correct… you checked the specified focus point and compared it to the factory specification …

This is exactly why you do it…


I have a set of 4 lenses, I know the focal length and I have done ramp tests on all of them. Like @bionicback321 advised, it’s more like a crap shoot to assume the factory focus specification is correct. My original factory lens was off a few mm. Pretty poor… I have much better results with a series C lens tube and holder.

It’s also much more flexible…

C-Series-Lens-Tube-2_500x500

You did everything right and confirmed the factory supplied the proper spacer.

So you did good, no go have fun :rofl:

:smile_cat:

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lol, will do Captain! Just have to figure out why my Air Assist isn’t firing the way it’s supposed to first. I think the solenoid is pooched… if not, I’ll be back on here asking again. Love first startup with minimal experience!

Jack, why would you have a bunch of different lenses? Do they perform differently from one another?

I can buy a telephoto a wide angle, macro and many more for my regular camera…

They are all lenses for different purposes… I have a 4", 2", 1.5" and a compound lens.

On the left is just after the head was functional, still has drag chain the original drive belt… On the right, more recent… no drag chain and a new drive belt.

This is how I can run 1650mm/s consistantly… not good for much except fun :rofl: Not much mass left on that axes.

I like my 2" for a lot of work, it’s a good general lens… I have a 4" for cutting thick mdf and acrylic or in general thicker material… The reason is that it’s ‘depth of focus’ is longer than a shorter lens, allowing consistent thick cut.

The drawback to longer lenses is they usually have a larger focus spot… mines around 0.2mm equates to an ability to engrave at 127dpi.

I can get approximately a 0.1mm (254dpi) dot with the 2", but I can get that down to about half that with a compound lens, or about 0.05mm (508dpi).

Again, you want a small spot for critical engraving, but with the small spot the focus has to be very accurate and the material flat or you run into the opposite of the long lens, a very shallow depth of focus.

You can configure them in different ways… such as a 2" configured for cutting compared to engraving… Most cutting, allows the nozzle to be close to the material to enhance the air assist functionality.

This is the configuration for the compound lens I use …

Might check out some of the Russ Sadler videos on lasing…
:smile_cat:

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That gauge is vital right after you whack the autofocus pen hard enough to dislodge it, whereupon you use the gauge while tweaking the pen position so it autofocuses at the right level again.

It’s also handy for setting the correct focus on material soft enough that the pen’s snout pokes into.

Also handy: a step gauge to set the focus in half-millimeter increments above or below the material surface.

So in other words opting for the Auto focus option was a pointless purchase…lol. No matter how much research I do I continue to get burned regardless.

Not at all, even if opinions around here differ.

I use it all the time for ordinary flat material: position the head, poke AutoFocus, and it’s at the right height.

For fabric / foam / paper / squishiness, the step gauge is definitely more useful.

FWIW, some controller settings let you fine-tune the autofocus height from the switch closure point, although you might want to save that for after you’re comfortable with the defaults.

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You’re the only one that I’ve heard that likes autofocus… My stuff changes so fast I didn’t think it was worth the trouble… Maybe I’ll revisit…

A little more difficult with my machine… no drag chain, so no electronics on the head or X axes…

:smile_cat:

IMO, autofocus is probably intended for “production” machines where the job operator runs material with (slightly?) varying thicknesses. Having one step in the procedure to get proper focus, without thought or manipulation, outweighs all other considerations.

Similarly for the focus distance settings in the machine parameters: a setup operator can tune the answer so the same procedure focuses a different lens, without retraining the job operator. Poke the button, run the job!

I got autofocus mostly to get a motorized platform, because a man’s got to know his limits: turning a stiff knob isn’t something I can do easily, so I sprayed (not too much, really) money on that problem to make it Go Away.

I’ve seen factory machine with this and I totally agree with your observation about factory machines using autofocus.

Once I ditched everything off the head that wasn’t necessary, I probably won’t to add more mass to it… not to mention getting the wires there…

:smile_cat: