Engraving My panels

[Buddym]

I built a cnc machine for about $650 not including software. I researched it a long time before deciding what to build. It is built from high density plastic using plans from the internet. It is very slow due to the power supply and controller running the stepper motors at only 12 volts, and using friction bearings made of Delrin instead of linear bearings. It works quite well, but not on Plexiglass. The slow feedrate causes the plexi to melt onto the bit and breaks the bit. (The VERY expensive bit, $35 each delivered.)

I bought a Probotix V90 Fireball kit about a month ago and have been cutting with it since then. It is 10+ times faster that my DIY machine and is very precise. I have cut 1/4" polycarb plastic at 90 inches per minute, which should be fast enough to try plexi, just working up my nerve to possibly break another bit.... The V90 is about $1000 delivered, not counting the router and software. It assembles in about 2.5 hours

Learning CAD/CAM has been the challenge for me, I only recently started getting acceptable results when engraving. The right bit and font make all the difference. If I was building the machine just for sim panels I might just buy commercial panels, since by the time you add up the machine, bits, software, and ruined material, it is probably just as expensive as buying panel kits, if not more so. I love to tinker and build different things so building a CNC machine seemed like fun. It was also very time consuming and frustrating at times (still is). Also very rewarding when you get good results.


BuddyM

In the hands of a skilled CAD/CAM/CNC operator I have no doubt that the V90 is capable of doing fantastic work. I am still learning CAD/CAM so my results are not anything close to what you will from Phil and others here.

[tomenglish2000]

BuddyM, your plexiglass problem might be because you are using Extruded Plexiglass. You will need to use Cast Plexiglass to stop it from melting.

Hope this helps. Tom.

[Buddym]

Thanks Tom,

I had heard that over on the CNC Zone forums as well, but have not picked up any cast plexi to work on. If I can get past that, then making nice backlit panels with engraving is now within my reach.

BuddyM

[phil744]

Tom is absolutly right in what he says, for light plates avoid extruded acrylic at all costs, cast is always better, its easy to machine and 9 times out of 10 you can get away without annealing.

I dont use CNC for my panels, i dont even own one (yet) but one thing i would say is be very careful when machining, you need to keep the router bit as cold as possable, probably get away with just using an air blower but water is always better, the reason is that if the router bit is too hot you induce thermal stress into the acrylic, basically the very edge of the freshly cut face has been hardened by excessive heat where as the rest of the acrylic is soft in comparison, if you look carefully sometimes you can see it, this becomes a problem when painting it because the chemicals in the paint softens the acrylic and cause microscopic cracks to form, you will not notice it a first but several months later you will spot light bleed through along the edges, ive seen panels from many vendors that suffer from this problem, using cast avoids this issue 90% of the time, if you are unsure cut a test panel and soak it for 48 hours in isopropanol, that will tell you if you will have problems, but if you kep the job cool whilst cutting you will be ok.

As for mounting panels for engraving i have a simple solution, the engraving is usually the last process before installing the hardware, some of my stuff requires cutting via laser after its been painted and engraved, basically I made a Dzus rail bed that accepts the pedestal size panels, assemble the light plate to its back plate then fit onto the Dzus rail, I always use the top left Dzus as a reference point for the art work/ cut work

[Buddym]

Phil, thanks for all the info, I have heard great things about your panels, so the info carries extra value. I will post some photos of my work when I get some cast plexi. I have also cut some panels from plain old polycarb, both black and grey, and then smeared the engraving with bright white enamel paint. I did flaps and speed brake panels like this and they came out great.


BuddyM

[Matt Olieman]

Excellent information Phil. Giving away all your secrets

Thanks for the info.

Matt Olieman

[Perik]

Yes, Phil's panel are great. I wish I could do the same......

My wishes for next Christmas is a 1 KW laser "burning" out the whole cockpit in one single run from of a huge block of acrylic... finished in a couple of seconds.

[Buddym]

that would be nice..... I don't think my Santa has the budget for that!


BuddyM

[riche543]

Hi all, I have been trying to hunt down a supplier of the fine mill ends here in australia & i have found one here is the link http://www.mcjing.com.au/categorybro...?categoryid=27 I was able to visit the shop as it is only 30 mins from where i live. You will notice the fine bits arent advetized on the website but they have the biggest collection of mills,drills,collets,etc etc,I bought some 0.45mm bits for engraving at $4.00 per piece. The lady in the shop is very switched on she will know what you are talking about as long as you ask for the correct bit you are looking for. anyway im sure this will help a few of you here in oz & save you $30+ on shipping , Doesnt feel as bad when you break a $4.00 bit. While expirementing with these bits i found 0.45mm gives me nice lettering not to wide you do have to be careful with the depth being so thin they will snap easy, also your work must be totally flat to the table ,which i had problems with earlier, then a simple soulution of some wide double sided tape, carefully stuck to the back of the panel, plus my normal fixtures on the side gave me good results. will post pics of these shortly. This is still all new to me ,But slowly getting the results im looking for.As said by others the cnc process can be very rewarding & disapointing , its fine tuning everything together carefully. I have varible speeds on my router, & have found depending on the bit being used to cut , slow speeds & feed have worked for me. (expirement). Is there a way of knowing if the plexiglass/perspex is cast or Extruded, Im using an old frosted sighn that used to hang out side a shop that was light up???? seems to work, Anyway will report back soon with some pics Cheers all .. Riche..

[Hessel Oosten]

It's funny to see here how several total different approaches can lead to great results.
As mentioned here before: patience, experience are far more important then some technical things.

Seeing this thread rather late will write some of my experience here.

Flatten underground. Engrave word by word or circle by circle and every time adjust the Z-height (because of the imperfectness of the material etc.). I make 3 or 4 rounds every time 0.05 mm deeper (depends on the thickness of the paint of course). Try to only remove the paint. When satisfied I stop the proces. With my finger I rub the the new engraving. The burrs drop in de new engraving but are now removed very well. After that one time more engraving removes everything and the white is really white. Try to fix the panel at the upper side. is more equal than from below. Mirror by making at the back, holes of the thickness of the mill, so in fact drill not mill (even if the holes must be widened later (e.g. for rotaries 6 mm). Using these small holes which fit narrow around the mill it's more easy to center the front side (the mill exactly fits in the hole !). I use (really !) ball nose mills .. from the dentist (0.3 mm). The reason is that they nearly make a flat path (in contrary to the V cutters). Flat would even better i.mo. but could'nt find flat end mills of 0.3 mm. The cut only removes the paint en does not go very deep in the acrylic material. This "flat bottom of the canal" is more Boeing like (to me). See also in fact the same comment of Per-Erik (Perik) in this thread. Less (!) translucent white acrylic gives a nicer appearence of the white when not backlighted. Never use backlight right behind engravings, always take as much distance as possible (diffuses the light too). Round all the edges (realistic and better for holding the paint).

Hessel