I am a manufacturer of Printed circuit boards. I have a need to machine precision depth controlled pockets in a circuit board mounted on a 1/4 in aluminum plate. I will also need to counter bore the aluminum and cut the board out. I was looking into a 3 axis router (thermwood, multicam etc.) does anyone have any experience with this sort of thing? are these machines capable of holding +/- .001 in the z axis. How would I hold the panel i.e fixture or vacuum. My panel sizes are typically 12x18in or 10x10. 1/4 in aluminum bonded to .030 circuit bord. I would also use it to profile simple 2D circuit boards. Thanks in advance for your help.
Positon accuracy of ANY machine is a function of the type of drive, the resolution of the machine and what sort of slop you'll tolerate when you build it.
Example: I have a 3 axis mill that can now hold withing a 0.001 or so in Z but X & Y are deadly accurate to 0.0001" or so.
This was after a tune up of the X-Y ways and ball screws and ball screw bearing replacments. The Z was left factory stock.
Prior to the "tune-up" we were lucky to hold 0.001 and there were 0.003 "flats" at X-Y direction changes.
Why deadly accurate X & Y and so-so Z??? We only cared abut X-Y preciseness and Z wasn't used in super precise fasion for the intended application.
The fix: time and money. Big money actually when it came to the ball screw bearings but that's what it took to hold 0.0001" position accuracy.
Lets say you have a belt drive router, you could hardly expect a "stretchy, droopy belt" with 200 count/rev encoders to hold the tolerance of a high $$$ ball screw drive that has preloaded and precision ground everything with 2000 count per rev encoders - the capability just won't/can't be there. IT will be good - probably withing a thou but ....... Time will tell.
I'd suggest looking at some commercial routers to "see" what they do and how they do it, as in hold the tolerances that you may be looking for. Then you can duplicate it more readily in a DIY fashion.
Technically, a HAAS VMC would EASILY do it as it is a grand and glorious "router". However, the cost is a far cry from a router, router. A HAAS tool room mill at about $29k would do so as well (within 0.0001). Again, more reasonable $$ wise but still a far cry from a router. Then there's the other end of the scale but you don't get within a tenth but it is going to be MUCH less co$tly......
Yes what you want can be done, it is just a matter of co$t and/or time to design and/or construct it....
Can a router be made to perform to your specs. Yes.
Yes, if it is engineered to do that and the parts needed to generate that performance are utilized and the control system is there to support that performance level.
I'd expect some router experts to chime in and explain how but you need to understand that the better the accuracy, the more sophisticated (read that as costly) you typically have to plan to be.
Never saw yet where a cheap anything out performed the high $$$ top of the line model. Life is just that way.....
Hey Steve, I (and many other here) route out the .002" layer of a 1 ounce FR4 copper board when making my prototypes. So yes, most of these machines we build hold that tolerance on all axis, typically, for this kind of work. I hold the PCB down with screws to the sacrificial material. A macro I use sets Z=0 for me so I rarely touch the sacrificial material at all. I like to fall short of bottom by a few thou so I can then break away the PCB. Four corner pins and a vac table would be ideal if you do this for a living.
If I interpret your explanation correctly your primary application will be machining precision pockets in aluminum. I feel you should be looking at a metal working machine. The Thermwood machines do not have the same level of precision; they may be adequate but when you are paying the amount of money involved for one of them you could get a metal working machine that is more than adequate.
That was a concern of mine as well. I may be asking a router to do too much. I first and foremost manufacture regular circuit boards that need to be profiled out of the panel. A regular 2 axis router (PDA, Excellon etc. ) would suffice for that function. I have recently received a lot of orders with the circuit board bonded to the 1/4 inch aluminum plate needing the pockets and counter bores. I have been outsourcing this machining to a Machine shop with a Fadal VMC. I really don't want to get a mill and a router if a good router would do the job. What would you consider to be the tightest toleranced 3 axis router. I hope to keep a good used price of 40k or under.
You need to check the specs for the routers you are considering. The only one I had experience with was a Biesse and it claimed a positioning accuracy of something like 0.004" and repeatability of 0.002". I am biased because I do metal maching with VMCs, but I think you have to take these figures with a grain of salt and maybe multiply them by 2. Metalworking machines on the other hand will have specs such as 0.0002" accuracy and 0.0001" repeatability and even if you multiply these by 2 you are still below 0.0005".
You can buy a NEW Haas "tool room mill" (TRM) for $29K and, I dare say, you'd have a kick ass one optioned out with tool changer for the $40K budget you discuss.
Have no clue on what a lease would be but that's an option as well.
A Haas TRM would make a dynamite 3 axis "router" (router or 'roids) if you had the spindle speed needed to cut G10. However, it would cut aluminum, steel, titanium, whatever which a router might tend to balk at.
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