Question for panel makers - engraving.. how do you do it?

[Stevos758]

Looks pretty dang good!

[Hempstead]

The right side is the real one from the real A-10 Simulator (won the bid on eBay, it's the whole self-contained lighting control unit including all the electronics and they use AC Variable Voltage Transformers instead of POTS!!! OMG, how much is one of those things costs when new???!!!!).

 

The left side is my reproduction. Laser engraved on the front, pocketed, outlined cut on an CNC'd RF-45. The large recess pocket on the back is for PCB for LED lighting (the original uses a phenolic board with aluminum foil as tracks and incandescent bulb for backlighting). The large recess was milled with a 3/4" and a 1/4" Osrund Carbide upcut endmil. Then, the whole thing is glass bead blasted.

 

Still needs to white fill the lettering, then paint the whole thing black... and finish my USB controller firmware. I write my own USB firmware for it using Atmel's evaluation board (and a Arduino Due, all 32bit ARM chips). It contains a FreeRTOS real time OS in it. And the whole thing runs multithreaded. It even has a running average digital filter to smooth out the noises. And it also has a over-sampling to "artificially" increases resolution to 16 bit ADC (to be honest with you, I think the oversampling is gimmicky). It is also capable of reading the Warhog/Cougar sticks (but only on selected models of Atmel chips that contains SSC modules, like SAM4S or SAM3X on Due). I am looking into support SAM4E chips, which has a real 16bit ADC on it, as soon as I get my hands on one of the boards.

 

The predecessor of this firmware powers my CH rudder, of which TARGET accepts it and I program it using TARGET and combined it with my Warthog. It's been doing that flawlessly for the last 3+ years.

 

I will OpenSource it soon (the Rack Mount server for it is already on my desk).

[Hempstead]

Here's a SOIC 8 complete circuit with an MLX90333 in an analog output configuration I did 5 or 6 years ago for the DiHXY hall sensor for Cougar, years before the Warthog. The WxH of the PCB is 0.65"x0.65". The SMD resistors and capacitors are 0805's.

 

Since it's a SOIC 8, the pitch is about 0.05", i.e. 50 mil and the width of the legs are about 15 mil. I used a 5 mil end mill. Due to runout of the spindle, the path it cuts is perhaps about 6 mil. The small traces to the capacitors are about 10 mil. except the power trace (20 mil) and you can see that not all the traces come out exactly 10 mil. The input/output legs are soldered in for IDC 0.1" pitch connectors. I would say anything smaller would be pushing it with this setup.

 

It's doable, but I must tell you that I had to tweak the backlash nuts of my tiny desktop mill so much that I actually ruined the backlash nuts. It's not very health for this mill to run such tight backlash! It actually would bind at the end of the ACME screw run. You probably would need some precision double nut ball screws to run anything smaller. But the good news is that very few sensors are smaller than SOICs (Unfortunately newer MCUs are often smaller LQPF 0.5 or even BGAs).

 

This is my prototype circuit so I left it bare without any coating and it oxidizes quite a bit.

[Warhog]

I have the stuff to make one I just haven't tried it out yet. I am "not" an electrical engineer so that is my hold up. : )

 

Here is someone using the machine I have to do them.

 

 

And someone using the autoleveling feature that would come in handy with panel making too?

 

https://www.youtube.com/watch?v=3sWVY89B7Gs

 

Looks like they turn out ok.

 

 

The term is actually "Auto Zero". It is a function built into Mach III and is dead simple to make. I made my own with a scrap piece of single sided copper clad board and an alligator clip. It comes in handy if you are constantly changing the zero for a variety of different thickness of materials.

 

Another little toy you can buy for a CNC mill is a web cam that you chuck up and then turn on the video window in Mach III. It looks down on your table so you can easily zero in the x and y axis. It has cross hairs like a rifle scope and there are 6 LEDs to light the area.

 

BTW, if I may suggest to all new CNC users that you join the CNCZone forum. There are several sections on desktop milling, engraving and Mach III.

 

There are a number video tutorials for Mach III on YouTube which will be important for new CNC users as well.

[DerekM]

The term is actually "Auto Zero". It is a function built into Mach III and is dead simple to make. I made my own with a scrap piece of single sided copper clad board and an alligator clip. It comes in handy if you are constantly changing the zero for a variety of different thickness of materials.

 

Another little toy you can buy for a CNC mill is a web cam that you chuck up and then turn on the video window in Mach III. It looks down on your table so you can easily zero in the x and y axis. It has cross hairs like a rifle scope and there are 6 LEDs to light the area.

 

BTW, if I may suggest to all new CNC users that you join the CNCZone forum. There are several sections on desktop milling, engraving and Mach III.

 

There are a number video tutorials for Mach III on YouTube which will be important for new CNC users as well.

 

Wow, that CNCZone forum has more sections than I've ever seen in any other forum! Thanks for the tip.

[Hempstead]

I don't think what the video demonstrated is the same thing as auto-zero in Mach 3. What the auto-leveller does is that it samples the z-height at multiple points on the board. Then PCB-GCode generates gcode with compensated z-height to account for the "unlevelness" of the board.

 

A couple lines of code, and some ingenuity and you don't need a complicated z-height compensation mechanism anymore. Absolutely brilliant!

[metalnwood]

I agree, it was the first time I had seen the auto-level, a user created program to map the height of the pcb at different points to cater for an uneven surface.

 

Very cool idea and def not the standard touch probe routine.

[geneb]

The trick is to surface your build platform before you start a job - this guarantees that the surface you start with is 100% flat and square to the cutter.

 

g.

[Warhog]

I agree, it was the first time I had seen the auto-level, a user created program to map the height of the pcb at different points to cater for an uneven surface.

 

Very cool idea and def not the standard touch probe routine.

 

But there shouldn't be that much variation in the surface of a copper clad board to begin with. I usually see issues because it isn't lying flat but that's what DS Tape is for.:thumbup:

 

BTW, Anyone here have a vacum table. I've been thinking about getting one no bigger than 8x10". DS tape is getting expensive and I go through quite a bit of it.

 

@DerekM... yes it sure is a mother of a forum. Lots of good info and that place covers everything you could think of related to CNC.

[geneb]

I've got a 10 zone vacuum table on my ShopBot. It's perfect for holding sheet goods.

 

You can use a 1/2" sheet of Ultralight MDF as a spoil board - the vacuum will draw right through it. Just paint the edges of it to prevent it from drawing air from the sides. You may have to remove about 1/32" from the front and back of the sheet to get rid of the hardened layers. They'll get in the way of a good draw down.

 

When I cut acrylic or metal parts, I use a double stick tape called "216" (go to http://www.harborsales.net and enter "3DCF" in the search box - it's $34 for a 3" wide roll, 72 yards long). I put that on the metal or acrylic and use a J-roller to stick it to a properly sized bit of Coroplast (think plastic cardboard). The benefit here is that you can cut a little deep and it won't break the vacuum as long as you only cut through the top surface of the Coroplast.

 

g.

[metalnwood]

But there shouldn't be that much variation in the surface of a copper clad board to begin with. I usually see issues because it isn't lying flat but that's what DS Tape is for.:thumbup:

 

BTW, Anyone here have a vacum table. I've been thinking about getting one no bigger than 8x10". DS tape is getting expensive and I go through quite a bit of it.

 

@DerekM... yes it sure is a mother of a forum. Lots of good info and that place covers everything you could think of related to CNC.

 

No there should not be much variation on the board but for those that might not have a completely flat surface and don't bother preparing it properly then I guess this could work for them. Like Gene says, you should surface the area first which is what the picture I had a page back was showing, a small area surfaced just for the engraving job.

 

 

 

I also have a vacuum table and I think I said it's only good for things over a certain size. I never tried it on the small acrylic because I don't engrave on the router but I gave it a quick look and it held down a piece of acrylic ~ 3x3" with enough force to do the engraving as the forces are fairly light.

 

The vacuum was sucking through 3/4" mdf to hold it. Any one of the small vacuum table plans around should be fine to make and use for this.

[Warhog]

:D

No there should not be much variation on the board but for those that might not have a completely flat surface and don't bother preparing it properly then I guess this could work for them. Like Gene says, you should surface the area first which is what the picture I had a page back was showing, a small area surfaced just for the engraving job.

 

 

 

I also have a vacuum table and I think I said it's only good for things over a certain size. I never tried it on the small acrylic because I don't engrave on the router but I gave it a quick look and it held down a piece of acrylic ~ 3x3" with enough force to do the engraving as the forces are fairly light.

 

The vacuum was sucking through 3/4" mdf to hold it. Any one of the small vacuum table plans around should be fine to make and use for this.

 

Really??? It will suck right through a piece of MDF?? That is truly amazing. I was wondering about a spoil plate and whether or more importantly HOW I could use it with a vacuum table. So the MDF is porous enough to allow the suction to carry through it. I need to try this for sure. That would reduce my consumables cost by a significant amount.:D

[metalnwood]

Certainly does suck through the whole sheet. The MDF on the vacuum table works well as the spoil board, every now and then you resurface it to get it flat again. I use a 5.5KW pump on mine but for smaller areas I see people using cheap vacuum cleaners for good results.

[geneb]

Garbage bags make great bleed mask if your spoil board is larger than the material you need to hold down. Just lay the bags flat around your material and turn on the vac. For small parts I'll use a single zone and one Fein Turbo III dust collector. A Shop Vac would work equally as well.

 

g.