Topics

Which not-so-Mini CNC mill #mill

Carsten Koester
 

Hi all,


at the risk of slightly hijacking the thread: Are there any specific recommendations for a *slightly* higher-class CNC mill?


If going from the initially asked US$200 budget to, say, $1500 to $2000 -- are there any specific devices that people have good experience with? Stepcraft D series was mentioned earlier on in this thread and looks like a solid choice at first glance to me; are there other opinions, or any other recommendations? When doing a Google search for Stepcraft (not specifically related to PCBs), X-Carve sometimes comes up as a direct counter-suggestion -- any experiences with that?


I guess I'm looking for something that may take some initial effort to set up (a kit is definitely OK and, in fact, preferred; and I don't mind doing some additional modifications/adjustments), but would be looking for something that after the initial setup is done, produces a usable board in a matter of minutes (or tens of minutes), not hours and without the need for continuous fiddling with.


Many thanks in advance,


-Carsten



On 2/12/20 9:27 AM, casy_ch@... wrote:
Hi

I tried to make suction/vacuum plates with styrofoam and it works quite well. It is easy and quick to make, once the drawing has been made
it just needs a soft rubber cord. I even milled small cases in hard plywood for measurement instruments on it

Jean.-Claude

Am 12.02.2020 um 07:01 schrieb joeaverage:
Hi,
I use doublesided tape to hold the PCB blank down and two 1.5mm diameter pins through the board to ensure
top and bottom side registration.

I use Autoleveller (freeware) as the height mapping utility. Today I did an circular PCB 80mm in diameter and there
was 0.18mm variation in height across the blank.  Autloeveller has a 3D visualizer that allows you to 'see' the variation.
If the variation exceeds 0.3mm over a 80 x 100mm blank I start looking for a reason, its not often necessary.


I don't have time to flycut the bed of my machine each time I make a board, I have ben making several a day at work
for some weeks now, I'd be lost without Autoleveller.

Craig


From: pcbgcode@groups.io <pcbgcode@groups.io> on behalf of John Ferguson via Groups.Io <jferg977@...>
Sent: Wednesday, 12 February 2020 4:47 PM
To: pcbgcode@groups.io <pcbgcode@groups.io>
Subject: Re: [pcbgcode] Which Mini CNC mill #mill
 
I agree that height mapping would be a good thing, but I don't have it. 
I hadn't thought of indicating my fixture after I install it but before
I fly-cut level it.  I can't get to this for a week or two, because I'm
building another shop setup, but when that's done, I'll show you what i
have.

john

On 2/11/20 9:19 PM, CJD wrote:
>
> I keep seeing this post about getting your bed flat.
>
> I don’t even worry about it.
>
> I get great results using the height mapping routine in candle.
>
> You cannot trust within .05mm a flat bed.
>
> When I height map there is almost always .5mm difference across a 10mm
> X 20mm piece of PCB.
>
> It gets even worse when the pcb piece is bigger.
>
> I don’t know how anyone can do this without height mapping.
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> *From: *John Ferguson via Groups.Io <mailto:jferg977@...>
> *Sent: *Monday, February 10, 2020 8:01 PM
> *To: *pcbgcode@groups.io <mailto:pcbgcode@groups.io>
> *Subject: *Re: [pcbgcode] Which Mini CNC mill #mill
>
> how did you get your bed flat?
>
> On 2/10/20 6:03 PM, Dan.Staver wrote:
>
> > I get good results using very thin double-sided sticky carpet tape to
>
> > hold the PCBs down for milling.
>
> >
>
> > Dan Staver
>
> > Tave Tech Corp.
>
> > 3130 Hollycrest Dr.
>
> > Colorado Springs, CO 80920
>
> > +1-719-359-5352 - office
>
> > +1-719-502-1675 - cell
>
> > tavetech - Skype
>
> > dan.staver@...
>
> > www.tavetech.com
>
> > W3QDO
>
> >
>
> >> On Feb 10, 2020, at 11:06 AM, John Ferguson via Groups.Io
>
> >> <jferg977@...> wrote:
>
> >>
>
> >> Maybe there should be a subject change. Have a look at the two
>
> >> fixtures whose photos I've attached.
>
> >>
>
> >> I make printed circuits which are about 2 inch by 3 inch. I found
>
> >> that I couldn't get reliable trace widths unless the board was
>
> >> absolutely level to the machine. So I started with an MDF fixture
>
> >> bolted to the milling table and drilled and tapped in four places so
>
> >> I could use nylon screws to hold the pcb down. Every time I do a new
>
> >> setup, I mill the surface of the fixture with a fly-cutter to level
>
> >> it.  This works 100% of the time. I've had no bad experience with
>
> >> PCB's not being of constant thickness.
>
> >>
>
> >> I had such good luck with the MDF board that I made a better one for
>
> >> HDPE. I also made a jig to drill the holes in the pcb so they would
>
> >> be sure to align with the ones in the fixture.
>
> >>
>
> >> Frankly, I don't see how you could ever get reliable cuts without
>
> >> leveling the surface the pcb is secured to while etching.
>
> >>
>
> >>
>
> >> john
>
> >>
>
> >>
>
> >> Attachments:
>
> >> DSC07301.JPG: https://groups.io/g/pcbgcode/attachment/8053/0
>
> >> pcb-etching-fixture&pcb-drill-jig.JPG:
>
> >> https://groups.io/g/pcbgcode/attachment/8053/1
>
> >>
>
> >>
>
> >>
>
> >
>
>





Attachments:

PETER HARRISON
 

Hi Carsten,

I have been using a Stepcraft 420/2 machine for "pcb" etching for more than three years now - with a great deal of success.

Having bought the kit (currently about £950 or so I think) and assembled and adjusted very carefully, the results are
really very acceptable.  Tracks and isolation down to 0.012" ( 300 microns ) are easily achieved, and with care and my home made vacuum table, tracks down to 0.008" ( 200 microns ) are feasible.

I currently use Eagle 9.5.2  to prepare schematic and board designs, and of course use pcb-gcode to prepare GCODE files.  Use interface software is UCCNC driving a UC100 interface adapter into the Stepcraft control electronics. No editing of GCODE is required apart from expanding the board outline milling cut to step down in 0.3mm increments to profile the board and separate from the unused laminate.  Double sided boards are quite feasible - I position guide pins outside the area of the board outline to ensure registration.

The spindle is a VFD industrial unit from StonyCNC, and this can be pushed to 24,000 rpm if desired. Personally I restrict this to 18,000rpm when "etching" and drilling up to 3mm diameter. Tools are held in ER11 collets. It's not cheap but is totally reliable and controlled directly from the GCODE. I can personally recommend it.

The vacuum table was milled from a hardwood block I happened to have, and screws down onto an aluminium table (Stepcraft option).  Sacrificial top layer is 1/4" MDF milled flat in situ and drilled to allow airflow (or lack of it!).  Pump is a relatively cheap "Chinese" unit, which is quite adequate provided expose holes are sealed.  Before holes are drilled this achieves a vacuum approaching -13psi effectively overcoming any warping of the laminate (FR4).

This week I made a 2.5" square board containing some 30 through hole components and a couple of IC sockets ( 16 & 28 way ) in about 30 minutes of machine time.  Tool changing and surface probing takes as much time again.  UCCNC will interface directly with my home made touch probe to set Z axis zero for each tool.

Regards,

Peter.


On Wednesday, 12 February 2020, 20:43:04 GMT, Carsten Koester via Groups.Io <carsten@...> wrote:


Hi all,


at the risk of slightly hijacking the thread: Are there any specific recommendations for a *slightly* higher-class CNC mill?


If going from the initially asked US$200 budget to, say, $1500 to $2000 -- are there any specific devices that people have good experience with? Stepcraft D series was mentioned earlier on in this thread and looks like a solid choice at first glance to me; are there other opinions, or any other recommendations? When doing a Google search for Stepcraft (not specifically related to PCBs), X-Carve sometimes comes up as a direct counter-suggestion -- any experiences with that?


I guess I'm looking for something that may take some initial effort to set up (a kit is definitely OK and, in fact, preferred; and I don't mind doing some additional modifications/adjustments), but would be looking for something that after the initial setup is done, produces a usable board in a matter of minutes (or tens of minutes), not hours and without the need for continuous fiddling with.


Many thanks in advance,


-Carsten



On 2/12/20 9:27 AM, casy_ch@... wrote:
Hi

I tried to make suction/vacuum plates with styrofoam and it works quite well. It is easy and quick to make, once the drawing has been made
it just needs a soft rubber cord. I even milled small cases in hard plywood for measurement instruments on it

Jean.-Claude

Am 12.02.2020 um 07:01 schrieb joeaverage:
Hi,
I use doublesided tape to hold the PCB blank down and two 1.5mm diameter pins through the board to ensure
top and bottom side registration.

I use Autoleveller (freeware) as the height mapping utility. Today I did an circular PCB 80mm in diameter and there
was 0.18mm variation in height across the blank.  Autloeveller has a 3D visualizer that allows you to 'see' the variation.
If the variation exceeds 0.3mm over a 80 x 100mm blank I start looking for a reason, its not often necessary.


I don't have time to flycut the bed of my machine each time I make a board, I have ben making several a day at work
for some weeks now, I'd be lost without Autoleveller.

Craig


From: pcbgcode@groups.io <pcbgcode@groups.io> on behalf of John Ferguson via Groups.Io <jferg977@...>
Sent: Wednesday, 12 February 2020 4:47 PM
To: pcbgcode@groups.io <pcbgcode@groups.io>
Subject: Re: [pcbgcode] Which Mini CNC mill #mill
 
I agree that height mapping would be a good thing, but I don't have it. 
I hadn't thought of indicating my fixture after I install it but before
I fly-cut level it.  I can't get to this for a week or two, because I'm
building another shop setup, but when that's done, I'll show you what i
have.

john

On 2/11/20 9:19 PM, CJD wrote:
>
> I keep seeing this post about getting your bed flat.
>
> I don’t even worry about it.
>
> I get great results using the height mapping routine in candle.
>
> You cannot trust within .05mm a flat bed.
>
> When I height map there is almost always .5mm difference across a 10mm
> X 20mm piece of PCB.
>
> It gets even worse when the pcb piece is bigger.
>
> I don’t know how anyone can do this without height mapping.
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> *From: *John Ferguson via Groups.Io <mailto:jferg977@...>
> *Sent: *Monday, February 10, 2020 8:01 PM
> *To: *pcbgcode@groups.io <mailto:pcbgcode@groups.io>
> *Subject: *Re: [pcbgcode] Which Mini CNC mill #mill
>
> how did you get your bed flat?
>
> On 2/10/20 6:03 PM, Dan.Staver wrote:
>
> > I get good results using very thin double-sided sticky carpet tape to
>
> > hold the PCBs down for milling.
>
> >
>
> > Dan Staver
>
> > Tave Tech Corp.
>
> > 3130 Hollycrest Dr.
>
> > Colorado Springs, CO 80920
>
> > +1-719-359-5352 - office
>
> > +1-719-502-1675 - cell
>
> > tavetech - Skype
>
> > dan.staver@...
>
> > www.tavetech.com
>
> > W3QDO
>
> >
>
> >> On Feb 10, 2020, at 11:06 AM, John Ferguson via Groups.Io
>
> >> <jferg977@...> wrote:
>
> >>
>
> >> Maybe there should be a subject change. Have a look at the two
>
> >> fixtures whose photos I've attached.
>
> >>
>
> >> I make printed circuits which are about 2 inch by 3 inch. I found
>
> >> that I couldn't get reliable trace widths unless the board was
>
> >> absolutely level to the machine. So I started with an MDF fixture
>
> >> bolted to the milling table and drilled and tapped in four places so
>
> >> I could use nylon screws to hold the pcb down. Every time I do a new
>
> >> setup, I mill the surface of the fixture with a fly-cutter to level
>
> >> it.  This works 100% of the time. I've had no bad experience with
>
> >> PCB's not being of constant thickness.
>
> >>
>
> >> I had such good luck with the MDF board that I made a better one for
>
> >> HDPE. I also made a jig to drill the holes in the pcb so they would
>
> >> be sure to align with the ones in the fixture.
>
> >>
>
> >> Frankly, I don't see how you could ever get reliable cuts without
>
> >> leveling the surface the pcb is secured to while etching.
>
> >>
>
> >>
>
> >> john
>
> >>
>
> >>
>
> >> Attachments:
>
> >> DSC07301.JPG: https://groups.io/g/pcbgcode/attachment/8053/0
>
> >> pcb-etching-fixture&pcb-drill-jig.JPG:
>
> >> https://groups.io/g/pcbgcode/attachment/8053/1
>
> >>
>
> >>
>
> >>
>
> >
>
>





Attachments: