Quote from Jason on December 26, 2020, 4:18 pm

Dave,

I have had good success with:

60 degree 1/8 shank” v-bit

depth of 0.012”

feed speed of 200mm/min

I have a spindle which I can slow down quite a bit versus a trim router which will run faster.

 

Quote from DrDave on December 26, 2020, 10:54 pm

Thanks Jason,

BTW, do you use vector text and engrave inside the vector or single line text?

Merry Christmas

Quote from Jason on December 26, 2020, 11:02 pm

You got it. I use vector text, or an outline font. You essentially do a pocket operation on the text.

Quote from DrDave on April 22, 2021, 2:08 pm

Hi Simmers,

Some of Hangar 45 builders use CNC for your text and lines on your panels. I am having difficulty with mine and would like your advice.

The results (I'd send a photo but sanded) are not clear and the paint rises on the edges.

I was unconventional. I used a 1/32 fishtail bit at .003 deep at first and couldn't really see letters (just a dent in the paint). I was using single line text.

I increased depth to .005 then .007. Seems the paint bunched instead of being removed. I'm using an all purpose Rustoleum paint, 2 coats.

I will have to go back and use a V-bit at 60°. I'll change my text to true type vectors and the lines to closed vectors.

Perhaps the paint I use is not correct.

Can you help me with this? Layers, colors other than gray, heat bake to dry, air dry?

I can certainly use Jason's input for the V-bit. But I think the paint is the problem.

I am using 3/8" cast white acrylic. Milled using Ron's DXF files. Thanks Ron.

Thanks for your help. There are few and expensive laser engravers here.

Quote from Jason on April 22, 2021, 6:25 pm

Dave,

Text is the hardest thing to do on a CNC. yes you need to use a 30/60 degree v-but for this. I would let the paint dry for at least a couple of hours if not more before engraving. The issue you described is because the paint is still not fully cured and just peels up around the tool edge.

As for the type of text, I suggest using a closed curve text font.  You can do a pocketing operation on the CNC to remove paint inside the characters. Additionally you will have to make sure your CNC bed is perfectly flat so that you don’t end up with some parts of the text under engraved and other over engraved. This takes some trial and error to get right, but nothing will replace the quality you get from a good “old fashioned” laser engraver.

Pro panels are made using several different kinds of paint. They use a white under coat then an acrylic layer over the top. They use a YaG laser to only burn off the top layer (the white layer is impervious to that wavelength). All of the buttons in your car are done the same way. Alas YaG lasers are extremely expensive so we are stick with C02 which will cut completely through our panels so you have to adjust the pulse duration and power to get the right results. Hope this helps.

Jason

Quote from Ron Rollo on April 22, 2021, 9:01 pm

Hey Dave,

Jason is spot on with all those points.  I will say that the CO2 laser at our local laser shop had to be precisely tuned and settings saved so that it was strong enough to burn through the paint and into the white cast plastic but not so strong that it burned completely through the plastic.  With the way we are forced to make backlit panels, the front panel is pocketed so that the actual front face of the panel in about .04" thick, plus or minus .005".  As you can see, these tolerances are very tight and no room for error.

Jason mentioned making sure the spoil bed is completely flat.  The best way to insure this is to "mow the grass".  Take the widest bit you have, in my case it is a .5" endmill and drop it into your spoil board about .05" or so.  Then run it back and forth like you are mowing the grass.   The end result is a perfectly flat working surface to mount your parts onto.  You may know this trick but I will put it out there just in case someone else can learn from this.

The paint we use for the front panels is Testors Model Masters Gunship Gray #1923.  It is a little expensive but is nearly perfect.  In the past there were several bad batches of it but I think all those cans have worked there way out of circulation.  (The paint never seemed to dry)  You can find this at hobby stores, Hobby Lobby has it also.

Engraving with a CNC is tough.  But if I were going to do it, I would use a 30 degree V bit.  Some folks suggest using a ball end bit.  But I think because the stuff we are engraving is so small, we have no choice but to use a V bit.  This like all CNC work will require some trial and error.  But it does help when you have some helpful tips to get started.

Quote from DrDave on April 25, 2021, 3:21 pm

I have been researching many ways to add text to the panels. I found a laser engraver here (original search didn't show). Asked for a quote.

However, as Jason mentioned burning the top layer and I found that aircraft manufacturers use silk screening for detail, I found this. Seems pretty straight forward.

Has anyone tried it.

https://www.youtube.com/watch?v=2hwHpkq_Vwc

Quote from Ron Rollo on April 25, 2021, 7:53 pm

That's great Dave.  I guess you are not concerned about back lighting?  Because this method will not get you there.  If this is your goal, non backlit panels, using stencils is a great way to go.

Quote from DrDave on April 25, 2021, 8:01 pm

You're right. Missed that.