Milling PCBs

[dare]

Hi -
Curious if anyone has tried milling copper clad FR2, or similar with their MillRight?

I am planning my order, and am considering spindle options. My primary use is PCB milling, but I'd want to do wood, and other materials sometimes. For that reason, I lean toward the suggested Dewalt DWP611 - looks like an all-purpose workhorse. However, I don't know if there are specific spindle types that are better for PCB milling out of all the suggestions on this site (i.e. rotary tool like my Dremel 3000 may produce more rpms, if that matters).

Any thoughts / experiences with that?
Any other considerations for PCBs I should look at?

Thanks,
Dare M

[Derek the Admin]

Hi Dare. Welcome to the forum. The RPMs matter for PCBs. Ignoring some other factors for simplicity, small diameter tools like to see a little more RPM. The DWP611 is going to top out at about 27k rpm. The Bosch colt will get you to 35k RPM. I don't care for it as much because the mounting surface isn't as appropriate as the nice cylindrical shape of the DWP611 and the "range" that you can clamp the body in is more limited, but it's a good router too.

The Dremels will probably have a little more run out, but you'll also need to run a collet adapter in the DWP611 or Bosch Colt (I have some that aren't listed yet, by the way) because those have 1/4" collets and most of what you are going to be working with in terms of cutting tools are going to be 1/8" shank I imagine. The adapter can add some additional runout, but I wouldn't be overly concerned about it either... just trying to give you the info. If you do go with a dremel, you'll want to look in the direction of a universal spindle mount like those sold by Inventables.

Consider carbide tooling over high speed steel.

One important consideration is flatness, but you and I spoke briefly about that over email I believe. I'd be taping, gluing the board down to prevent any convexity or concavity from screwing up your traces.

Also, that composite is not good for the ol' lungs. Wear a dust mask for sure.

[dare]

Thanks for the info. Yes, even though the FR2 is paper composite, not fiberglass - I'd rather not breathe it.

I have milled PCBs on the Roland Modela MDX20 - and the double-sided tape worked great. Looking at the specs, the Roland runs only at 6,500 RPMs - surprisingly. Sounds like the small rotary tools (Dremel, etc) have too much run out. Looking at various forums, the DWP611 is well-loved - and sometimes, but not always for PCB milling. I will do more research!

Out of curiosity - has anyone here done any PCB milling with the MillRight? If so - what spindle are you using, and what results have you gotten? Any pics?
Thanks!

[Derek the Admin]

It's been a while and I didn't take any pics. I've had another prospective customer ask to see some PCB works so I went over to rapid-pcb.com (great site, check it out) and generated g code on their demo board for the 45 degree v bit I had laying around. I used an inexpensive collet adapter to hold it in my DWP611's quarter inch collet. That probably introduced a hair of eccentricy to the rotation, but hey, I'm not building space shuttle parts here.

I decided I'd run 400mm/m. That's a pretty decent clip for PCB milling. I've seen some feed as slow as 100mm/m. Here are some pics of the board after it got hit with wet sandpaper.

http://instagram.com/p/BMDayE3AWtY

http://instagram.com/p/BMDbnghAUpX

http://instagram.com/p/BMDb-bzgnC5

[dare]

Hey, that looks great! I was wondering how the 611 would handle fine lines. Even with the imperfect collette, looks solid. Thanks for doing that.

I will definitely be investing in a MillRight. I am in the middle of a couple big (non-cnc) extracurricular projects that will not allow me any time to build the kit until December, or so. I plan on ordering by end of year. Thanks

[Derek the Admin]

Sounds good Dare. We will be here when you are ready. Hang around here in the interim and you will be that much more ahead of the curve.

[dare]

Hi Admin -
If I can pick your brain for a moment, I am making some preparations to order the M3.
On the Roland Modela, I used 4-flute 1/32", and 1/64" end mills (1/8" shank). However - I believe the DeWalt is 1/4" shank, and I see you are using a V-shaped bit, which I have never used.

- What is a reasonable collette
- What starter bit would you recommend for PCB milling with the DeWalt 611? Benefit of V-bit over tiny endmill (maybe less breakage?).

Thanks

[aforww]

I'm gonna need y'all to get the machine ASAP. I need a small simple but tiny circuit made on a as small as possible PCB. And making PCBs is not something I've ever done lol.

[Derek the Admin]

Dec 6, 2016 23:58:56 GMT dare said:

Hi Admin -
If I can pick your brain for a moment, I am making some preparations to order the M3.
On the Roland Modela, I used 4-flute 1/32", and 1/64" end mills (1/8" shank). However - I believe the DeWalt is 1/4" shank, and I see you are using a V-shaped bit, which I have never used.

- What is a reasonable collette
- What starter bit would you recommend for PCB milling with the DeWalt 611? Benefit of V-bit over tiny endmill (maybe less breakage?).

Thanks

I won't claim to be an expert on PCB milling, but I can say that the V bit is a pretty popular choice. That copper is not very thick on the board, so a v bit would theoretically allow for finer traces that the end mills. I would not say it's "wrong" to use a v bit. It is perhaps less prone to breaking that a 1/64" end mill, but there is a disadvantage to a v bit... and that's tramming issues causing inconsistent width.

I use the stock DWP611 collet with a cheap collet adapter. We have some we could sell you pretty cheap if you needed a one or two. Many like to talk about how the adapter can introduce eccentricy (true), but you'd probably only notice a difference on a really high end machine with really good measurement tools.

[dare]

That is all very helpful. I will get back to you about the adapter, if needed.
Thanks

[dare]

Haha - AFORWW, I'd be glad to help you once I'm set up. Probably won't have the Millright built and running until some time in January (I'm letting my kids "buy" it for me for xmas).

Send me the block diagram, maybe I can help you before then, depending on what it is.

[aforww]

Dec 7, 2016 18:22:42 GMT dare said:

Haha - AFORWW, I'd be glad to help you once I'm set up. Probably won't have the Millright built and running until some time in January (I'm letting my kids "buy" it for me for xmas).

Send me the block diagram, maybe I can help you before then, depending on what it is.

Pretty basic for you types that are good with such things. My electric knowledge is mostly home, automotive definitely not boards. Just a photocell, watch battery, and LED. not sure what goes in between them all. Lol. I'm sure there's a resistor and cap in there somewhere. Basically, lights go off, led comes on and vice versa. Just need it in the smallest form factor possible.

[Derek the Admin]

Dec 7, 2016 18:19:07 GMT dare said:

That is all very helpful. I will get back to you about the adapter, if needed.
Thanks

No problem.

Aforww: That takes me back to about a decade ago when I decided I wanted to invent some things so I started learning electronics. I've forgotten more than I know at this point, but I'm thinking you create a voltage divider on the gate of a transistor with a fixed resistor and the LDR, biasing it as needed, using the transistor to switch the LED. Dare or Dan could probably give more guidance.

[ronjodu]

Dec 7, 2016 6:24:19 GMT Derek the Admin said:

Dec 6, 2016 23:58:56 GMT dare said:

Hi Admin -
If I can pick your brain for a moment, I am making some preparations to order the M3.
On the Roland Modela, I used 4-flute 1/32", and 1/64" end mills (1/8" shank). However - I believe the DeWalt is 1/4" shank, and I see you are using a V-shaped bit, which I have never used.

- What is a reasonable collette
- What starter bit would you recommend for PCB milling with the DeWalt 611? Benefit of V-bit over tiny endmill (maybe less breakage?).

Thanks

I won't claim to be an expert on PCB milling, but I can say that the V bit is a pretty popular choice. That copper is not very thick on the board, so a v bit would theoretically allow for finer traces that the end mills. I would not say it's "wrong" to use a v bit. It is perhaps less prone to breaking that a 1/64" end mill, but there is a disadvantage to a v bit... and that's tramming issues causing inconsistent width.

I use the stock DWP611 collet with a cheap collet adapter. We have some we could sell you pretty cheap if you needed a one or two. Many like to talk about how the adapter can introduce eccentricy (true), but you'd probably only notice a difference on a really high end machine with really good measurement tools.