- Syed Imran
First a description of my skill set; I work with Linux computer systems and have both formal training and practical experience with electronics. I have no previous CNC experience.
I have used Eagle CAD for PCB layout using the toner transfer method and my desire is to set aside the chemicals. I have a paid hobby version of Eagle CAD and the gcode ulp setup and working.
I have mill ends for the CNC; 1/32" 2 flute and a .005" micro endmill (I want to try smd path isolation).
The demo video indicates milling an mdf board to provide a level work field. How is this done?
I assume that milling the board in that fashion will provide me proper Z height for my pcb milling? And advice or insight would be appreciated. I hope to give it a go this coming weekend.
Milling exactness and also control and also the situation on the milling bits and also the respective feed data transfer rates. By contrast, from the element etch method, the caliber of any circuit panel depends upon the exactness and high quality on the photomasking plus the talk about on the etching chemicals.
I'm looking for a pcb milling and drilling CNC under $1000. Is this a turnkey machine I could get, or should I be looking at something else?
Your question is difficult to answer:
The machine itself can be ordered as turn key.
Means there is a complete Installed available.
Depending on the Software you are going to use it is a couple of hours to get it running
If you order the Complete Kit, there is about 1 1/2 Days of installation work.
In case you are going for the mechanical Kit only.... well than some Engineering and purchasing for the Electronics comes on top ;-)
The other point is: What PCBs you want to do?
As finer you require it, as more you might have to modify.
Let me be straight: This is not a 3000$ Machine (where most of the PCB Mills start) and there for it has some short falls. Any How, with little effort (and replacing the Spindle) it is a very good tool. I would not give mine away ;-)
I am very close to purchase this machine but I need to know if it's possible to mill a QFN foot print package . PCB is what I want to do with this CNC but I have really small components to work with. QFN is very small foot print...It would be great to achieve this with a 600$ CNN machine
looking forward for response
to be able to do QFN Isolation you will have to be extra carefull assembling the machine.
I have replaced the table with a thicker (for cutting a Plain surface into it) and improved stiffnes in Z Unit.
Then for the Isolasion Milling I have figured an V Carving bit 60° 0.1mm
Money effort for those as about 16US$ for the Board and the bit.
I hope this helps a little?
See you around
Have you tried any QFN Isolation with the machine ? If yes would you be so kind to post some pictures .
sorry I don't have yet a Board with QFN ready. still under design
The manual is very good! Even though you will have to skip everything were Stephen is mentioning drilling. By now all holes are drilled already which makes installation much easier.
Extra care is needed to make everything really square. This is mentioned in the manual several times as well and I only can repeat it
In order to get decent result for very fine isolation routing it is extremely important that your Spindle Axis is really square to every spot of the mills table. To achieve that I have replaced the original 5mm one with a 15mm one and use the Mill to make a plain surface. This only after I have made sure the spindle Axis is really vertical.
With that I believe it is possible to do QFN as well
See you around
Thank you for your quick reply. My understanding is that I need to be careful with the machine assembly. What is to be aware of ? Any guideline ? Are the assembly directions that come with the machine instruction book detailed enough ?
Thank you again for your reply.
In cambam (free version),
I change the measure to inches, insert a rectangle, change the dimensions to 4 height and 4 width and lower left point to 0,0,0. I insert a new pocket, change the final depth to .25 and changed the depth increment to .125. I'm using an 1/8" end mill so I changed the tool diameter to .125.
Save the file and "create g code file", and load kcam.
Sanity check, will what I did so far work (maybe not optimum, but functional)?
The mdf I have is 8x10x3/4" but I am not placing it on the bed yet...
Open kcam, click File, open the g code. I have red lines in a square, the cut path I assume. No end mill, no mdf so I can see what it does but won't damage anything. I click cnc controls, automatic tab and start. It moves some and pauses; I'm not putting an end mill in it and hit play. It looks like the pocket is at the level of the bed approximately. That is, if I had 1/4" mdf, it would cut a hole in it.
Second sanity check, does that sound correct?
Do I make mdf depth settings in cambam or kcam?
Thank you, Charles
Yes, EagleCAD with the pcb-gcode plug in does a great job, though it can be quirky. You'll need to tweak the settings by running pcb-gcode-setup in the command line and adjusting there to match your intended output and your end mill parameters. Keep some scrap PCB board for testing the settings until you get your desired results.
As long as your end mill is spec'd for PCB isolation track milling you should be good. We use V-bits in preference. They have more lateral strength because of their shape and the track milled can be further adjusted in width by adjusting the depth of the cut. That allows for some tweaking without having to rebuild the g-code. We use a 20-degree V for fine work.
We created a square 4x4 pocket milling g-code profile in CamBam and simply attached the MDF to the table with carpet tape and had the machine mill it's own 4x4 flat surface. It's an elegantly simple way to ensure a level surface relative to the spindle/Z axis. We used a general purpose 1/8" end mill to get wide cuts/pass and make quick work of the task.
You then attach your PCB blank to the milled surface. You can use carpet tape or pinch screws. We prefer pinch screws but be sure to not over tighten them they don't need to be tight to firmly grip the board. We use the screws to press the board into the edges of the milled pocket. We drill the pilot holes tight against the board edge at a slight angle so that as we tighten the screw the head of the screw exerts more lateral pressure on the board to pinch the opposite side into the pocket. You can see this in the last PCB video we just posted. If you over-tighten the pinch screws they can bend the board slightly, defeating the purpose of the level bed. That being said, sometimes the blank boards have a curve to them. We tend to reject those, but sometimes you can use the pinch screw pressure to offset the bow and get a flat board. Carpet tape is best to hold down a board that is not completely flat (as seen when eyeballed along its edge).
Hope this helps,
What cutfeed rate, plunge feedrate, and spindle RPM do you use for making the MDF bed? Is there a rule of thumb?
Also, in Kcam under "Table Setup" there are "Feed Rates" and "Max Feed Rates". Do these override the feed rates that I set up in CamBam or do the feed rates in the gcode override the "Table Setup" in Kcam?
I tried making the MDF bed doing two passes at a .125" depth per pass, but either the feed rate wasn't right or my end mill is crap. Also, the end mill kept coming loose from the spindle and I can't tighten the spindle any more.
I thought I'd note as well...
I had to order a cable a week ago because for all my planning and buying a parallel port card, and end mills, I didn't think to buy a cable.
The end mills I bought from Drill Bit City; I emailed them to ask about what kind I needed and then purchased sizes I thought would be useful. I decided I needed a 1/8" end mill to clear mdf for the bed, and I ordered one of those from Amazon. I have Prime so the shipping is faster, and I could order just one for that purpose.
I ordered some V ends last week; I wasn't able to find them in the US so I ordered from China. 15 degree, 1mm; we will see how they work.
This weekend I attached the end stop switches and wired them up, and finally sat down late Sunday evening to try driving the machine.
The StarTech PC Card parallel port I have for my laptop would not drive it. It is going back to Amazon and I picked up a cheap desktop and lcd monitor on Craigslist. For the record, I read the warning about laptops, but I already owned an older one so I wanted to give it a try.
In CamBam, I changed the unit of measure in the dropdown to inches, made a rectangle and used the details to change it to 4x4. Then I created a pocket in it that was 1/4" of an inch deep. Then saved the gcode.
Originally I was going to use Ubuntu, but I am working on a 3D printer (Prusa Mendel RepRap) in parallel and had trouble with the software in Ubuntu. And since the same computer will control them both...
KCam didn't work with the PCMCIA/PC Card parallel port card. The card did not correctly detect the input pin statuses. My guess would be they only built enough of a card to use for printers.
When I get through the adventure, and have working etchings I want to document the process from 0 to etched so someone else can use the information.