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Author Topic: issues with PCB milling - newbie  (Read 7825 times)

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Re: issues with PCB milling - newbie
« Reply #10 on: April 30, 2012, 10:27:06 AM »
If it was me I'd take it apart completly  and clean any packing greases of the ways. set the nuts on the shafts and assemble one by one. Ajusting the gibs before the instalation of the nuts. also checking the the trust bushings/bearings preload.

you may also try posting the machine make in the title, maybe you can find a fellow user
Re: issues with PCB milling - newbie
« Reply #11 on: April 30, 2012, 10:49:43 AM »
Thomas,
Consider posting where you live if you don't have reason not to do so, and perhaps there may be a more experienced member nearby who can visit and help you.  It really sounds as though you need a good mechanic, not software users, to help you first.

Regards,
John Champlain
www.picengrave.com
Florida
Re: issues with PCB milling - newbie
« Reply #12 on: April 30, 2012, 03:54:57 PM »
You're right - I need a mechanic! I live in Denmark, now moving to France in a couple of weeks

I managed to get the machine running again, but it is not perfect - I milled a square on a PCB and it is not true; 62mm vs 63 mm... The Y axis is really not precise, when milling a PCB using a double path, the second path does not exactly match the first  really crappy precision

On the "backlash" thread, Rich gave me the advice to fasten the nut to the Z-block when the Z-block is at the end of its run on X - it works now.

TramAlot - what is a gib? I googled "Gib milling" and got lots of pictures, none of which said what the gib is. Also I realised that what I called a "spindle" is actually a screw... a spindle being entirely different. The issues of never having learned technical english...
And how do you check the thrust bushing/bearing preload?

Thanks a lot for your help folks - will come back with more questions tomorrow!

Thomas
Re: issues with PCB milling - newbie
« Reply #13 on: May 02, 2012, 12:46:20 AM »
I played with PCB milling for years.  I never got what I called consistent results.  I even built a vacumm hold-down board to ensure the board was flat.  I changed all my screws to near zero backlash, etc, etc, etc.  I finally gave up.  There were a number of us working on the problems with outlining copper paths, tools overheating, gummy copper and other things.  I finally went to an outside processor, Sunstone, who makes the boards almost overnight and ships them drilled and plated for about the same cost as the carbide cutters I ruined over and over.

I finally found a solution, at least partially, by making a floating pen holder and using my mill as a plotter.  I used black and red sharpie brand pens and dipped the boards in hot FCL and they came out great.  If you go this route, you will need to drill after you plot since the gummy copper chips will spin on the drill bit and ruin the plot.

Jerry

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Re: issues with PCB milling - newbie
« Reply #14 on: May 02, 2012, 02:08:07 AM »
I don’t know if posting this here will be of any help but PCB milling is good for certain applications but not so good for others.

I make quite a few prototype PCB’s and for simple circuits the ‘isolation routing’ method is probably the quickest and cleanest method I have ever used, particularly if there are drilled holed or machined profiles etc as with a couple of tool changes the whole process can be completed in minimal time. As a layout starts to become more complicated and particularly if there are large areas of copper to be removed then the ‘print and acid etch’ method comes into it’s own and it is really just a matter of deciding where the break point occurs.

This little PCB was made by isolation routing and represents a mornings work from creating the layout to producing the prototype.

Tweakie.

KEEP SAFE !
Re: issues with PCB milling - newbie
« Reply #15 on: May 02, 2012, 11:57:43 AM »
http://cnccookbook.com/CCBacklash2.htm

great site for other information also
Re: issues with PCB milling - newbie
« Reply #16 on: May 05, 2012, 06:07:06 PM »
Tweakie -
very pretty board, what is it used for? Do you place the components in the hollowed-out places? Very elegant

thomas
Re: issues with PCB milling - newbie
« Reply #17 on: May 05, 2012, 09:15:01 PM »
its for a probe. tweakie is beyond a master craftsman ...

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Re: issues with PCB milling - newbie
« Reply #18 on: May 06, 2012, 03:22:27 AM »
Spot on guys.  ;)

The PCB is for a low profile probe and by mounting conventional components within the boards thickness the overall height can be reduced. I am looking at other alternatives such as pocketing a slightly thicker top cover to accommodate the components and so on. Ah the joys of R & D.

The milling / isolation routing technique is certainly quick and easy for this type of work and although the small engraving cutters impose very little loading on the machine it is pretty essential to have as near to zero backlash as is possible and of course, a perfectly flat and true work table.

Tweakie.

KEEP SAFE !
Re: issues with PCB milling - newbie
« Reply #19 on: May 06, 2012, 03:37:13 AM »
Really nice board!

On my thread on backlash ("   Re: newbie - help with solving backlash issues") I posted this - do you think I could solve some of my backlash using the Mach3 Backlash correction? I am concerned of tried to reduce it by tightening the nuts won't improve things (I am a lousy mechanic) ... thanks

Hello,

Now looking at the backlash on the Y axis. I ran the G-cpde below (also attached) on my small mill. Basically it mills from x=0 to x= 10 mm line in MDF, goes up 150mm, mill a parellel line... comes back and does a line at x=10 to x=20... etc.
Issues are: at Y=0 the three lines are not completely aligned, there is a bit of "ladder" effect. Same with the lines at Y=150 mm
The distance between the lines at Y=0 and the lines at Y=150 is not truly 150mm - more like 148.5
these problems looked even worse when I tried to mill then drill a PCB

Shall I fix this by trying to removed the backlash "mechanically", or should I try to use Backlash correction in Mach3 (as suggested by Hood)?

-to check reliability, is the program attached/below the right way to go? I made a couple of circles as well - but I don't have high precision instruments to measure the distances accurately (electronic vernier calipers is all I have)

many thanks

Thomas


F100
G21
G01 Z2
G01 Z-0.5
G01 X10
G01 Z2
G01 X0
G0 Y150
G01 z-0.5
G01 X10
G01 Z3
G0 Y0


G01 Z-0.5
G01 X20
G01 Z2
G0 Y150
G0 X10
G01 z-0.5
G01 X20
G01 Z3
G0 Y0


G01 Z-0.5
G01 X30
G01 Z2
G0 Y150
G0 X20
G01 z-0.5
G01 X30
G01 Z3
G0 Y0