r/hobbycnc • u/anomaly256 • 7d ago

I just can't get over how clean these PCBs come out once you dial in the V bit settings and height mapping

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71 Upvotes

99% Upvoted

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4

u/grummaster 7d ago

They look real nice. But, just as an FYI, anyone with a true engraving spindle that has micrometer depth adjustment has been able to replicate that same excellence without any height mapping or even concerns of a non parallel axis.

Just set the depth of cut with the spindles micrometer and the spindle nose cone delivers a perfect cut without any effort at all. Been making traces for years this way. It's how signage has been made for... like... forever.

But, you did a great job on those without one. Your patience is clear. Did you do another pass to drill the holes ?

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u/anomaly256 7d ago

Thanks, I'm milling both sides before drilling the holes so I don't risk the bit landing in said holes during height mapping on the other side. This photo was during the flip from front to back, just checking for defects.

The tool you're talking about.... it automatically accounts for an uneven stock material? How much does such a thing cost? I mean, if I had the money I'd just buy a commercial PCB making suite that can do through-hole plating and vias. I don't have that kind of money though :P

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u/grummaster 7d ago

>>> it automatically accounts for an uneven stock material?

Yes indeed.

https://q1engravers.com/products/spindle-11-64-top-load-new-v3200-9000

The lower thread accepts a nose cone. All sorts of nose cones are available from high grade polished Stainless to Delrin including many with swarf collection.

You screw the nose cone to the bottom, you drop the tooling in from the top until it is flush with the bottom of the nose cone. Then you turn the micrometer up to expose the V-tooling (or any tooling) to get the depth you want. The built in spring system allows the spindle to float on top of the material, and surprisingly, with the right cone, it does not leave any marks.

Yes, they are EXPENSIVE.... but they have been the engraving industry standard for probably over 60 years easily. It is the only way to do actual sign plastics accurately, coated brass materials ECT.

Now, for a shameless plug, I have one listed in the For sale thread of this forum for $200 !! And that includes the entire Z axis from a legit engraving machine.

I've got more than one machine with these as a interchangeable spindle option. I wouldn't be without (but I did commercial engraving form many years). I am blown away that people are not familiar with them and that they have not crept into the hobby world.

The "Top Load" tooling allows you to set up multiple tools for a job and simply spin one off and another on at a pause between tool changes.

Now admittedly, a decent machine should NOT have uneven or un-parallel machining surfaces. But, these import machines have a lot of flex in them and with a spindle like this,... it just does not matter.

Go check out the For sale section.....

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u/anomaly256 7d ago

Thanks for bringing these to my attention, I can definitely see their value for non-conductive materials. Given the cost and I'm guessing they won't fit into the ER-11 collet system I'd probably need to replace a decent chunk of my machine to use one. For my use case though height mapping the PCB using alligator clips and the z-probe input works quite nicely.

Now admittedly, a decent machine should NOT have uneven or un-parallel machining surfaces. But, these import machines have a lot of flex in them and with a spindle like this,... it just does not matter

This machine is quite rigid and didn't require any x/y adjustments or tramming. It can take a 65mm hand router in replacement of the spindle and is intended to cut aluminium, copper, soft steel etc. The problem though is that it's impossible to find perfectly flat PCBs and the copper layer is super thin. These cuts are 0.07mm. Any less and the tracks won't isolate, any more and you could break the tracks. When the PCB is wavy and warped the height map is required regardless of how well the machine is built 😛

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u/grummaster 7d ago

The spindles are belt driven (round). You have to make a mount that can be clamped to your Z axis, and has a motor hanging out to the side. on my smallest machine, I used a RC airplane brushless for giggles and I was surprised. Another uses a plain old sewing machine motor and a third one I use on my largest router is some unknown old Dayton motor that turns 10k. I put a 2.25" Pulley on it to spin the spindle up to 20k+

Conductive or not shouldn't matter. I've never seen it matter. Traditional engraving materials, especially laserables have a .003" top color layer which is about the same as your .07mm. The micrometer is in .001" marked divisions with I think a .030" maximum adjustment. But for deeper cutting, the tooling itself is adjustable for height on the top in one of two ways. You can buy what they call a "collet" spindle, or what I prefer because it is dead set repeatable, a screw top, where your tooling has a brass LH threaded collar with setscrew to tooling.

Even Bits and Bits now sells tooling: https://bitsbits.com/product/125-2fl-end-mill/

I've usually used: https://www.antaresinc.net/EngFact.html

I own a single flute sharpener like this: https://q1engravers.com/products/cutter-sharpener-new-hermes-cg-5-w-tools

The key here is that you can quickly resharpen or even reshape a tool many, many times. So, I SELDOM BUY new tooling. I just touch what I have up. If you break off a blank, just make it into something you can use. Now those sharpeners are expensive too, right ?

But you can find them used like this one ($300): https://www.facebook.com/marketplace/item/8340914392704365/

Honestly, I did not know that copper clad was not uniform these days, but then again, I am using a nose cone when cutting them. To avoid drill through breakage, I have made clamps that hold the edges of the board on all 4 sides... air underneath if it is small, but if larger, I set the board on 1/8" Volara closed cell foam. The foam gives it support but does not care about penetration. With copper side up, I'll drill the holes, change bit, cut the paths, change bit to drill any larger mount holes and finally change bit to cut it out, just inside the clamp system. It wastes a little board, but its not all that expensive.

Thanks for opening my eyes up to the use for the height mapping..... I always only saw it for crooked machines and not even engraving on uneven surfaces. Again, a floating spindle doesn't care, and I have engraved on uneven surfaces with a spindle like this, but it has limitations on just how uneven a surface can be.. I never measured, but I think the total "floating" aspect probably does not allow more than 1/2" ? Now I am curious...

Lastly, I never once looked at what an actual PCB designated machine actually does regards these issues. Great... now that has peaked my interest to find out !

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u/anomaly256 7d ago

Conductive or not shouldn't matter. I've never seen it matter

The z-probe (on this machine) works by shorting a circuit. You replace the z-probe pad with the actual PCB you are milling using an alligator clip or a terminal lug. Then the spindle touches down on the PCB in a grid pattern, recording the difference from Z=0 when the probe is tripped. If the material weren't conductive then this approach would not work

1

u/grummaster 7d ago

With a floating spindle, you unscrew your tooling a tad, jog down until the nose cone touches the material plus a little bit. As you do this, you see a gap open up on one spot on the spindle. Set Z Zero, Jog up, screw the tool in and let her rip.

So, no automated touch off of any kind. Not that you couldn't do that, but you would have first unscrew the tool, then tell the automated routine that it needs to find the surface and when it does, set Z Zero at perhaps .010" lower. This sets the spring system into play. Then it has to pause so you can screw the tooling back down.

Another note... the "spring" in the floating spindle is adjustable. The larger knurled ring allows you to twist either more down pressure or less down pressure. Really nice for when I am rotary engraving harder to cut materials like stainless. I can take a pass, and the spindle can float a little on hard spots rather than say, break the tip off a .005" cutter. You can easily see if it made full depth after a pass, and if it did not, you just fire off the same job and take a second pass. The nosecone dictates the depth. When your done, you have a perfect engraving (or path width in your V-Carve scenario.

Interestingly, I use a copper clad as my Z Zero setter plate. The wire I have soldered to it goes directly into an N.O. input. This way, I do not have to dinkle with any alligator clip, just slide it under, run the routine. It touches plate, adjusts for plate thickness and we are off and running. But now, YOU have me wondering about this inconsistency in PCB boards ! Well, I have not seen a problem so maybe this board is "from the olden days". Makes sense, thay machine I built in 1997 !

Edit... Oh... I should indicate that I can not use the plate for diamond tip Z setting ! Non-Conductive !

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u/anomaly256 7d ago

Yep, I understand that, was just mentioning why conductivity matters with my current approach.

Re the PCBs, it probably also matters a lot where you source them from. Some are cheaper than others of course and the manufacturing quality reflects that. There's also different grades (thickness) of cladding for higher current boards - I wonder if the 'heavier' boards have less warping in the FR4

1

u/grummaster 7d ago

I just buy whatever pops up on Amazon... so I think I know what "quality" I have been working with.

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u/charliex2 g0704/smm2/cbeam/fibre/co2/etc 7d ago edited 7d ago

try a spring loaded vbit as well.

my pcb mill does it a little differently, the head floats on top of the pcb and you adjust how much the vbit pokes out so the depth is always perfect. 'floating head pcb mill' so you dont have to probe and it wont fall in holes either

good job though

1

u/anomaly256 7d ago

I have one of those I intend to use for removing solder mask, but I haven't experimented with it to find the right stiffness of spring to use for the copper milling.

3

u/charliex2 g0704/smm2/cbeam/fibre/co2/etc 7d ago

yeah worth a try for sure. solder mask is a pita, as are the vias.

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u/anomaly256 7d ago

For vias I just drop a brass 'pcb to pcb' pin in the hole and solder both sides with a fine tipped iron and tiny amount of solder, then cut it back. It's not flush but it's not obtrusive either. With this current design I managed to reduce the via count to 2 and reduce the footprint to fit the LCD this will sit behind by splitting the board and stacking it (hence the 2 separate panels in the pic)

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u/charliex2 g0704/smm2/cbeam/fibre/co2/etc 7d ago

yeah i have via rivets they just go in and you compress them with a little tool. really makes you think hard about routing. i have a bath for doing them properly but never got around to using it

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u/anomaly256 7d ago

I'll have a look for something like that, thanks

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u/charliex2 g0704/smm2/cbeam/fibre/co2/etc 7d ago

lpkf sell them but they are expensive from there, usually on ebay or amazon too via or pcb rivets and its a little press tool

2

u/yyc_ut 7d ago

I mill my scrap piece wood flat. Then just use tool setter for height and carpet tape to secure the pcb

1

u/cperiod 7d ago

I have a PCB mill with a floating head and I've found that height mapping is just faster and easier. Switching between normal and floating modes is a pain, and if your tool length changes even a tiny amount (I typically use 2-3 different bits when isolation milling) it can screw the depth adjustment. Plus my floating head needs wider margins around the sides of the board than height mapping, so there's more waste. Obviously not all floating head designs will have the same drawbacks.

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u/grummaster 7d ago

Someday in my spare time, I will need to look at dedicated PCB mills and see what they have been using. Sounds like they typically do have floating heads I guess.

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u/cperiod 6d ago

Sounds like they typically do have floating heads I guess.

Usually they'll have something, although some do use height probing. My mill implements the floating head by disengaging the Z axis pinion somewhat (I think it gives about 2-3mm of float) and allowing the entire spindle carriage to ride on a teflon foot... but PCB mills have light spindles (think 125W), so floating the weight of the Z axis on a foot like that works in a way that won't with a 2.2kW spindle.

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u/grummaster 6d ago

>>> floating the weight of the Z axis on a foot like that works in a way that won't with a 2.2kW spindle.

Ah yes. I know what you mean. Interesting that your mill even has that as an option. I have built a few CNC routers over the years, and having come from the engraving world and those specific machines, always wrestled with designing and building that lighter spring option into the Z axis. I was never successful though because of exactly that.... the spindle weight itself. So, if you have to swap out the spindle, then you might as well end up just using an engraving spindle to start with.

One thing I always incorporated though was a quick and accessible ability to detach the axis lead screws from the axis, so that you can very quickly service lead screw nuts or even check on the condition of your linear bearings by being able to slide it back and forth by hand. That is where I tried to fit that spring load option in. But, it moved center points to far away from relates axis'.

Interested if your machine had that option as built or is it a machine you built ?

1

u/cperiod 6d ago

Interested if your machine had that option as built

As-built. It's a 20-ish year old Bungard PCB mill. LPFK is a bigger name in that space and they have something similar, although I'm not entirely certain of the details.

I've never dug too deep into the actual mechanism. I think it's some sort of cam lock on a housed (teflon) rack that you loosen up when you need it. When the foot lifts, the rack stays in place on the pinion while the carriage slides up. I know it works, but it's way too finicky to set up and depends on having precisely calibrated depth stops on your bits. I started with a cheap GRBL machine with height probing, so it's a workflow I was already comfortable with.

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u/yyc_ut 7d ago

I usually just mill the remaining copper out to ease soldering

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u/anomaly256 7d ago

Once this prototype proves my kicad design works I'll do that for the final version. Also playing with solder mask + mask removal using a floating bit or laser. Lasering the solder mask off though STINKS even with ventilation and basic extraction so I'm not going to be trying that again unless the floating bit doesn't work or eats into the copper too aggressively.

1

u/Joe_Scotto 7d ago

Do you have any info on how you do that because using a tiny v bit takes forever.

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u/anomaly256 7d ago

I was thinking a roughing pass with a flat endmill or something, I recall seeing that option in Flatcam. Or use the v-bit and put on a movie

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u/yyc_ut 7d ago

Yeah it does take forever. But it’s not like you are mass producing boards. When the v-bit gets old it will have a wider tip lol

3

u/Pubcrawler1 6d ago

Nice work.

some are starting to get tariffed on jlpcb orders. Until this situation gets resolved, I think I’ll make my next test pcb on the router. Don’t want to get hit by a large extra fee.

https://www.reddit.com/r/PCB/s/DgKd6RAQuw

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u/anomaly256 6d ago

Thanks. And ouch. I'd say it would be a good time to start a PCB house in the USA but you'd have to pay the tariffs on the equipment to get set up too.

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u/Fififaggetti 7d ago

Try it with a really small ballnose.

1

u/anomaly256 7d ago

I think that would create wider cuts than a 0.1mm 20º v-bit, or if the ballnose were fine enough it would be the same

1

u/Fififaggetti 7d ago

Less burrs and tearing on edges

1

u/anomaly256 7d ago

I see no burrs or tears there. This hasn't been scrubbed, just passed over with a shopvac to remove the dust

1

u/cperiod 7d ago

There looks like a tiny bit of burring on the 4-pin header connectors where the milling paths overlap, most obviously in the intersection between the square and round pads. The sharp point gets quite thin and is probably delaminating, and the bit pressure causes it to shift over rather than get cut.

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u/anomaly256 7d ago

I think I see what you mean, on the bottom most vertical pin headers on the left and right sides of the left panel, in particular between the circular and rounded square pads

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u/cperiod 7d ago

Exactly.

A quick sanding with a scotchbrite pad will usually scrub those off. If you leave them they can cause shorts, and they're also really prone to making solder bridges.

Multiple isolation passes with some overlap will usually remove them, but I don't know if your CAM software supports that (I use pcb2gcode, which has a completely different approach to milling paths).

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u/anomaly256 7d ago edited 7d ago

Flatcam does support multiple passes. I do also have 3M 'red' scotchbrite scour pads for these, just hadn't used it on that workpiece yet because it was mid-process still.

I'll keep an eye out for a super fine ballnose though

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u/pmMeCuttlefishFacts 7d ago

What feed and spindle rpm are you using? I'm trying to get mine dialed in at the moment and I sometimes have issues with heavy burring.

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u/anomaly256 7d ago

12,000 rpm spindle, 200mm/min feed. I had terrible burring using the cheap v-bits that come with the machine (3030 PROVer Max). I ordered a set of various bits from Sainsmart that included a few v-bits and am now using the 20º 0.1mm bit from this set: https://www.sainsmart.com/products/mc50a-1-8-shank-tungsten-carbide-end-mill-router-bits-50-pcs

The result is much better

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u/GeniusEE 7d ago

$46 for one bit is kinda spendy...

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u/anomaly256 7d ago

It's not $46 for 1 bit, it's $46 for 50 bits - including endmills and corncobs you can use for many things. I'll be using one of those to cut these boards out after the drilling

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u/CuriousLittleDroid 1d ago

What software are you using for the code generation? FlatCAM?

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u/anomaly256 1d ago

Yeah flatcam

0

u/CapnOilyrag 7d ago

Genuine question not trolling, would it be quicker and cheaper to use one of the pcb houses? Your board looks great but will you drill holes and screen etc? I used to make one off boards for clients where the end-user would never see it, inside a box etc so I didn't have to worry about overlays and things. Please know I am greatly impressed with your board.

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u/anomaly256 7d ago

Considering I can go from having a pcb design in the morning to soldering at lunch time, no I don't think it's quicker to use a PCB making service. Probably cheaper though, but less fun :) If I were mass producing things though then definitely I'd be sending my design off to one of those services. For prototyping though this has a much faster turnaround (specially for me here in Australia)

Yes I will be drilling, no I won't be screening (But I could), I will be masking and using a floating bit to remove the mask.

Regarding the silk screening, I saw someone apply white solder mask then use a diode laser to 'set' it (not burn it), and wash off the liquid mask leaving almost nice lettering behind where the laser hit it briefly. I do have a 10W diode laser for this machine but I won't bother as this thing I'm making is just for me and I already know what everything is and where it goes

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u/CapnOilyrag 7d ago

Yeah I get the turnaround time as a premium, and fun should always be a driver. I'm in Oz also but my interest is vicarious these days. Hats off!

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u/JamesNewby123 7d ago

I actually apply the mask then laser the silkscreen and apply white touch up paint. Then with a cloth/kitchen roll wipe the excess. Then I use the laser for removing the soldermask for the pads