Engraving My panels

[riche543]

Hi guys , Well ive finished the CNC build , Have almost masterd the software & cad drawings ,G,code etc etc. My question is about engraving my panels with my machine , I have found that I cannot get my lettering fine enough , could anyone give some advise on engraving white perspex, I do think i need to change the bit but is there any other tips you guys could give me Chhers all !! Riche......

[fweinrebe]

Which tip are you using?

[riche543]

Thanks for the reply im using this bit the TV 2208 one
http://www.apworkshop.com.au/html_ro...ffb-vg225.html Cheers..

[brianwilliamson]

http://www.precisebits.com/products/...oreengrave.asp
These are the bits I use.
Regards......................Brian W.

[riche543]

Thanks for the reply Brian, Which of those bits would you use for the lettering on your panels, Do you buy them from US or can you buy them here in australia. also any tips on the process its self for perspex speed/depth/ etc etc Thanks again Rich..

[Buddym]

Yes, I wanted to know what angle bit you are using as well....and since we are asking Brian lot's of questions, here's one more: What size font are you using?


Thanks,
BuddyM

[Perik]

Hello BuddyM

I have lately used a 0.4mm (or smaller) Endmill single flute (not V-cutter) with success.
Attached an image from SheetCam showing a part of the VOR panel in a B767.
The cutout of the letters is approx. 0,5mm wide and I'm cutting "Inside Contour".
I feel that the Endmill gives me better control of the width compared to the V-cutter.
When passing the panel paint, the width is final – that is not the case with the V-cutter.
I do two passes - one “Up cut” and one “Down Cut”.

Just some ideas which you could try…..

Forgot the Font question:

Mostly using "Futura Md BT" - Font 12.

[brianwilliamson]

Ok I mainly use the 60 degree ones. The 30 degree are very fine and if you do not have a very accurate spindle that does not have any runout, then you will easily break the tip off. As far as the depth goes you need to experiment with that to get the width you like the look of.
These bits are not available here as far as I know, so you will have to get them from the States. They are very fast on delivering orders.
The font I use are Stick40, and the size of course will vary according to the panel used.
Hope this helps..................Brian W.

[lear45fan]

Dear Richie,

first of all I would reccomend you use futura single line font. For engraving I'm using different tips with diiferent width to design how thik the line has to get. from 0,1mm t 1,5mm. thats the best way to have a good quality engraving. If you need single line futura just send me an email and I can send you an ABC in Futura or you use a program called text to dxf which includes a single line editor.

regards Mike

[vcimmino]

I just tell mine in this topic.

Engraving with the CNC is a long trial and error, and even an expert user sometimes ruin a piece for small forgotten details...

Anyway,
In my opinion only Vbits should be used to engrave the panels, other bits types might scratch or chop the paint. What angle mostly depends on the finishing type you want to have. Very sharper angled Vbits (10-25°) will give you a blind effect and harder to backlight, but more contrasted. 30-45° Vbits are the most used as a medium range. Wider Vbits (>60°) will tend to let perceive light floodings around the letters. Some people might like it some not.

All of those bits can be bought almost anywhere in the internet. Ebay has tons of sellers having them for cheap in all the flawours you might like. You can freely buy them in 10 packs but you won't use more then 1-2 to engrave panels as only paint has to be removed and is a very light job. Also consider the tip size. The best is always something in the 0.1-0.2mm range, that will give you enough freedom to engrave the most complex and even smallest chars. 0.5-1.0mm ones will be useful for bigger text and will speed up the engraving. Buy a set with various sizes if you can...

The most used font for panel engravings is the Futura Md BT (In truth the Futura DemiBold, but it's really hard to find and the Md BT is very close). This is not a personal choice but a rule of the MIL specs. Obviously the problem is that we don't have only to choose the right font but also the right depth of cut, the right bit and the right path allowance when cutting to acheive the best result.

My own is usually acheived by planning the text in the size I like in illustrator, make it outline, export to the CAM software (I use Artcam), make the engraving path with the 45° 0.2mm bit, 0.1mm depth and leave some small allowance to the paths. In this way I will be able to engrave a first time and check if I like it or bold a bit the chars by reducing the allowance and make a second run.

Usually two passes always give a cleaner result; the first removes the paint, the second clean and sharpen perimeters, so having 2 diffs paths with my method just speed up things and prevents from unwanted extrabold chars.

To end with, always check that your panel has the very same thickness in all of his parts. Irregular sheets are more usual in acrylic cast then polycarbonate (like perspex is) but check it anyway. Even 1/10th mm (0.004") difference matters. If a part is thicker then other you will finish for sure by having a very bad engraving in the part where the perspex is taller, because the bit will dig too much into the plastic.