Backfilling engraved frontpanels

After much trial and error I figured out how to get some g-code written to engrave front panels on a Haas mill. Yesterday I did a test run on some spare aluminum and everything came out great... but I have a potential problem when I do my final engravings.

On the bare aluminum, it was necessary to use a scouring pad to brush away the small burrs and chips left over from the engraving before I backfilled with an ink pen.

This is fine on a spare aluminum test panel, but I don't want to scratch up the anodized aluminum surface of the "real" frontpanel for my MILA.

Does anyone have a suggestion of a non-abrasive way that I can remove any smalls burrs and chips from the engraved text?

Thanks.

Mason

I have a local engraver do my rack panels - he is an expert and I am always pleased with the results he gets - my preferred panels being black anodised, so the engraving cuts through into the silver layer below. They look fabulous - and don't seem to have sharp edges or burrs.

I'm sure that his answer to the problem would be 'sharp tools' - but I guess that the profile of the cutter is important also.

You are fortunate indeed to have the equipment and ability to do this yourself and I'm sure with more experimentation and experience you will get great results.

JG

Don't forget to run tour spindle at high speed, at least 20000 rpm is recommended.
Theoriticaly, the center of your engraving mill don't turn, so , in order to have a proper cut you have to turn at high speed.
Use also a proper tool for engraving, this also affects alot your finish.

Thanks for the comments guys. The mill that I have access to can only go up to 4000 RPM spindle speed... so 20K is out of the question right now. There is some talk of getting a high speed upgrade though.

For my first tests we only had a few tools laying around, so that is part of the problem. The really nice 60 degree 3/8" carbide tool is much too large for engraving small text, but it makes really, really nice lines that are pretty much devoid of burrs or chips. The tool that I had to use for engraving the letters is not as nice, it's not carbide. Simply put, I need to purchase a better tool for text engraving.

Also, we are having a small problem with the coolant flow right now... better coolant flow would help remove the chips whilst engraving.

Mason

Yeah, it's definitely an rpm or low quality bit problem.

[quote author="Ptownkid"]Yeah, it's definitely an rpm or low quality bit problem.[/quote]

Yeah, I pretty much figured that.

Though by and large the results are pretty good (especially for a first run), just enough small burrs here and there to be a bit annoying.

Do you have any suggestions for a good place to pick up carbide bits? (I'm new to all of this...)

Mason

bitsbits.net

Carbide bits ain't as sharp as hss. But can potentially last sooo much longer.

I think that if you are using the right cutter that you wont have much in the way if burrs. You can run a burnishing bit after engraving as well.

Check out these links:
http://www.antaresinc.net/2004EngFAQ.html
http://www.antaresinc.net/2004EngFact.html

Thanks for all the help everyone. I just purchased some new bits. I'll post results when I get everything done.

Mason

While we are on the topic of engraving ....

When engraving anodized aluminum black panels, how do they 'fill-in' the color in the engraved characters?

Is that a special pen and ink?

Sources to buy?

yeah, i'd love to know this too. There is no way someone sits there with a syringe and does it...

[quote author="Ptownkid"]yeah, i'd love to know this too. There is no way someone sits there with a syringe and does it...[/quote]

I don't know about what kind of paint they use, but I think I saw on the old FPE website a photo of a girl filling in the engraving with paint using a syringe. Then wiping the excess off.

That's why it's so expensive having text filled in.

[quote author="Carl_Huff"]While we are on the topic of engraving ....

When engraving anodized aluminum black panels, how do they 'fill-in' the color in the engraved characters?

Is that a special pen and ink?

Sources to buy?[/quote]

I'm not sure how commercial places do it, but I used a "Uni-Paint" paint pen to backfill my engraved letters. It looks pretty nice, you just have to be careful in removing any excess that spills out. I used isopropanol to remove the excess. It also looks better (more full and complete) when you apply the paint pen at least twice.

I picked up the paint pens at Johnson Plastics. They also have some nice reverse-engrave plastics if you're doing faceplates or nameplates for guitar amps.

Mason

Try drag-tip engraving with a spring-loaded drag-tip engraving bit. You turn the spindle off and just drag across the anodizing with a diamond tip.

http://www.talkshopbot.com/forum/messages/312/30430.html

I bought this one:








You'll need an air-compressor for it. With a footswitch you can avtivate the spraying device. The small box also makes a vacuum - so no drops. There is some special colour available for the colour filling but it works with other laquer without a problem.
BUT. You need some experience.

@Mason:
Don't try to remove burrs and chips. Better solve the problem. :grin:
Engraving with lower speed than 20.000 turn/min could be a problem. Maybe you can buy a cheap hobby spindle for 100€ and mount it to the z axis.

Frank.

Cool ...

I see that you are using an EFD fluid dispenser. Who sells the actual color that you are dispensing?

The blue colour is a pretty normal colour from the building center.
Its "synthetic resin varnish". Available everywhere.

The trick is to put the colour into the engravings. It lasts some month until it worked for me. Its like etching pcbs... there is no 100% success guide which works for everyone everywhere.

Frank.

Frank,

That's beautiful work! I've gotten decent results with a paint pen but your method is obviously much better.

I just picked up some new bits that should be considerably better than what I used in my test runs, so hopefully that will help. I don't really have the option of going to higher spindle speeds right now. I'll look into the hobby spindle idea that you mentioned.

Mason

My calculator says 2mm/s feed for the X/Y axis with 6000 turns/min for a 0.2mm tool. (my feedrate is 12mm/s but with a highfrequency spindle)

For engravings you shoud use a Minimal Quantity Lubrication. Or at least put ethyl alcohol on the panel. Thats important. You'll get much better results. If that don't work try to engrave in two steps... 0,1mm and then another run with 0,1mm again to achieve 0,2mm.

If your engravings have a different width on the panel you either need a mechanical or an electronic device which regulates the z-height. If you're doing the cnc program manually with G-codes its probably not that easy to engrave some text deeper when they're not deep enough at the first run. A cad/cam program would make everything much easier. :wink:

Whats the type/name of your cnc machine?

Good luck!

Frank.