CNC PCB milling
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@executivul said in CNC PCB milling:
Imho wheels on rails will never ever ever be as stiff and have less flex than the lousiest linear bearing. Wheels on rails are for printers and lasers.
Even in the case of the Rattm Motors 6040, where the z-axis is hanging off an X-axis that is dangling by unsupported smooth rod? Is it still better even then?
@neverdie it might be better than a rigid x axis aluminium profile dangling on some wheels all together. Then comes the profile joining piece dance.
On the cnczone forums people go like: linear rails are the best, round bars are good, wheels on rails are for toys. That is for normal milling on a small machine. These things are routers by the way, real mills are taig style and are small size and meant for steel and heavy metal milling (no pun intended). For wood, plastic, soft stuff it might be acceptable though.
For pcbs you need high precision, flatness, high rpm etc.
For wood you need large size, think of table or door pieces. Tolerances are not so tight. You won't go like: look! Your door engraving is 0.1mm off in that corner!
For metal you need precision, high rigidity and power at lower spindle speed.The classic ebay cnc is a good all around tool but excels at nothing 😁
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@neverdie it might be better than a rigid x axis aluminium profile dangling on some wheels all together. Then comes the profile joining piece dance.
On the cnczone forums people go like: linear rails are the best, round bars are good, wheels on rails are for toys. That is for normal milling on a small machine. These things are routers by the way, real mills are taig style and are small size and meant for steel and heavy metal milling (no pun intended). For wood, plastic, soft stuff it might be acceptable though.
For pcbs you need high precision, flatness, high rpm etc.
For wood you need large size, think of table or door pieces. Tolerances are not so tight. You won't go like: look! Your door engraving is 0.1mm off in that corner!
For metal you need precision, high rigidity and power at lower spindle speed.The classic ebay cnc is a good all around tool but excels at nothing 😁
@executivul
How thick is the aluminum that such a 6040 machine could mill? -
@executivul
How thick is the aluminum that such a 6040 machine could mill?@neverdie you must use a chipload calculator according to your spindle power at requested rpm, tool diameter and tool profile. Stock can be as thick as you want, the machine has about 100mm of z travel, you mill in multiple passes anyway so milling depth per pass is based on the results from calculator, experience or many broken tools.
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Interesting way to make an inexpensive closed-loop stepper motor:
https://youtu.be/s2dpCpUqGnEI think a better way to do it would be to directly couple the encoder to a dual-shaft stepper motor, but that would, of course, mean purchasing a new stepper motor. Nonetheless, these small stepper's are pretty cheap.
The other way to do it with the existing single shaft stepper but without a belt might be to use a magnetic encoder, but I can't say that I've tried that, so I'm not sure how hard the retrofit would be.
Also, I guess the main point in doing this would be to hotrod your CNC, to make it move faster without skipping steps. i.e. you probably don't absolutely need to hotrod your CNC.
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Interesting way to make an inexpensive closed-loop stepper motor:
https://youtu.be/s2dpCpUqGnEI think a better way to do it would be to directly couple the encoder to a dual-shaft stepper motor, but that would, of course, mean purchasing a new stepper motor. Nonetheless, these small stepper's are pretty cheap.
The other way to do it with the existing single shaft stepper but without a belt might be to use a magnetic encoder, but I can't say that I've tried that, so I'm not sure how hard the retrofit would be.
Also, I guess the main point in doing this would be to hotrod your CNC, to make it move faster without skipping steps. i.e. you probably don't absolutely need to hotrod your CNC.
@neverdie said in CNC PCB milling:
I think a better way to do it would be to directly couple the encoder to a dual-shaft stepper motor, but that would, of course, mean purchasing a new stepper motor. Nonetheless, these small stepper's are pretty cheap.
I never looked, but do they make a dual notched pulley? Then you would only need to buy a pulley vs an entire stepper.
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@neverdie said in CNC PCB milling:
I think a better way to do it would be to directly couple the encoder to a dual-shaft stepper motor, but that would, of course, mean purchasing a new stepper motor. Nonetheless, these small stepper's are pretty cheap.
I never looked, but do they make a dual notched pulley? Then you would only need to buy a pulley vs an entire stepper.
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@neverdie it might be better than a rigid x axis aluminium profile dangling on some wheels all together. Then comes the profile joining piece dance.
On the cnczone forums people go like: linear rails are the best, round bars are good, wheels on rails are for toys. That is for normal milling on a small machine. These things are routers by the way, real mills are taig style and are small size and meant for steel and heavy metal milling (no pun intended). For wood, plastic, soft stuff it might be acceptable though.
For pcbs you need high precision, flatness, high rpm etc.
For wood you need large size, think of table or door pieces. Tolerances are not so tight. You won't go like: look! Your door engraving is 0.1mm off in that corner!
For metal you need precision, high rigidity and power at lower spindle speed.The classic ebay cnc is a good all around tool but excels at nothing 😁
@executivul
This guy bought a 6040 CNC with supported y-axis rails (just like the RATTM one), but starting at time index 4:52 he discusses the "well known problem" of flexing on the 6040's unsupported x-axis when milling aluminum:
https://youtu.be/6a57KtmIu-4He concludes that upgrades to the 6040 (e.g. possibly a supported x-axis rail) will be necessary.
It's just a pitty that an inexpensive, already "upgraded," 6040 isn't for sale. Instead, it becomes a DIY quest.
In fact, this guy did do the x-axis supported rail upgrade, but it solved only 50% of the problem:
https://youtu.be/ABLXVCkXmpg -
@executivul
Do you suppose that linear rails, rather than supported rods, would fix this twisting problem that people seem to be having?i.e. Notionally, something like:
https://www.ebay.com/itm/Portable-Steel-MGN12H-Linear-Sliding-Rail-Block-Tool-250-550mm-CNC-3D-Printer/382360155951?var=651145928342&hash=item590670f72f:m:mah05n6MWl2QkZTLIZW2vJQ
that's made out of steel. -
@coddingtonbear What materials are you milling ?
I want to get a spindle for mostly wood, just hobby, but don't want to go too cheap, and face buying over when I realize its just not > W
@rfm69 Almost always just PCBs. Maybe sometimes some acrylic, but nothing very solid, if that's what you're asking. Those little 1610 CNCs have so many plastic parts, that I'm not sure it'd perform very well cutting anything much harder than plastic.
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@rfm69 I believe so, at least for brush motors. For brushless, I get the impression the motors are missing the electronics which tell them when to alternate their currents internally, so (it appears) you need a special driver to make them move at all. I'm not sure how, or even if, PWM fits into that. Maybe motor speed is all managed entirely through the brushless controller, and all the brushless controller wants as input is pure DC?
@neverdie Yes; brushless motors are for sure more technically complex than brushed, and usually require an external driver. Most of the time those drivers have inputs allowing you to control the speed via PWM or an analog voltage.
Adapting the 1610's woodpecker board to supply that PWM speed control signal to an external driver is super easy -- I can show you a photo of what I did to mine if it'd help.
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@executivul
Do you suppose that linear rails, rather than supported rods, would fix this twisting problem that people seem to be having?i.e. Notionally, something like:
https://www.ebay.com/itm/Portable-Steel-MGN12H-Linear-Sliding-Rail-Block-Tool-250-550mm-CNC-3D-Printer/382360155951?var=651145928342&hash=item590670f72f:m:mah05n6MWl2QkZTLIZW2vJQ
that's made out of steel.@neverdie said in CNC PCB milling:
@executivul
Do you suppose that linear rails, rather than supported rods, would fix this twisting problem that people seem to be having?i.e. Notionally, something like:
https://www.ebay.com/itm/Portable-Steel-MGN12H-Linear-Sliding-Rail-Block-Tool-250-550mm-CNC-3D-Printer/382360155951?var=651145928342&hash=item590670f72f:m:mah05n6MWl2QkZTLIZW2vJQ
that's made out of steel.Yes, but MGN15 or larger and of better quality, but that is expensive...
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@neverdie said in CNC PCB milling:
@executivul
Do you suppose that linear rails, rather than supported rods, would fix this twisting problem that people seem to be having?i.e. Notionally, something like:
https://www.ebay.com/itm/Portable-Steel-MGN12H-Linear-Sliding-Rail-Block-Tool-250-550mm-CNC-3D-Printer/382360155951?var=651145928342&hash=item590670f72f:m:mah05n6MWl2QkZTLIZW2vJQ
that's made out of steel.Yes, but MGN15 or larger and of better quality, but that is expensive...
@executivul
I guess the difficulty of finding a satisfying solution to this problem explains why milling machines are built around a stationary, highly rigid z-axis. ;) -
@executivul
I guess the difficulty of finding a satisfying solution to this problem explains why milling machines are built around a stationary, highly rigid z-axis. ;)@neverdie And finding a good tool at an affordable price is a challenge. Specialised machines do a s specific job better than general purpose ones, but only do that job. Professional machines do a better job at a higher price tag. We are just poor hobbyists :)
I'm so happy with my $50 UT61E, what a great multimeter, of course I would rather have a HP 8.5 digit one any day but I'd rather spend that money on a holiday or something since I don't need that 0.0001uV precision anyway, at 1V a 3V bat is as empty as a 0.9999999987V one if you get my point. Too many times I've spent a fortune for professional tools which I don't use/need so I tend to get what I need + a small margin, for eg I got a huge DSLR and lenses, used a few times, great photos, but lately, guess what, I tend to use my phone for taking photos 99.9% of the time, the camera backpack is just too heavy to carry arround .
Get a 3d printer, get a 3040/6040 cnc, get a 40/50W laser, get a lathe if you have space for it, maybe get a vertical mill for metal parts and you'll have a maker space of your own, as long as you won't start manufacturing space ships ebay tool tolerances will be ok.
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Reminds me of a quote from the MPCNC website (https://www.v1engineering.com/frequently-asked-questions/ ) :
Diminishing returns kicks in really fast in the CNC world.
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I suppose, in theory, that somehow replacing the x and z-axis with these might mitigate against the twist problem:
Presumably the rails are precisely spaced and held perfectly flat by the base plate, so you'd avoid binding problems that might otherwise arise from a purely DIY manual retrofit of just the rails.
I don't know what the MGN number is for that rail though, so I don't know whether its MGN15, MGN20, or something else.
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@neverdie said in CNC PCB milling:
@dbemowsk said in CNC PCB milling:
a dual notched pulley
I don't know what that is.
I wasn't sure of the exact name for it, but I was referring to something like this:
https://www.amazon.com/ReliaBot-Aluminum-Timing-Pulley-Printer/dp/B079JGYYKV/ref=sr_1_5?s=industrial&ie=UTF8&qid=1520378263&sr=1-5&keywords=dual+timing+pulley -
@dbemowsk
I take back what I said earlier. I like the way this guy did it better, because with the gearing you can get even more resolution out of your encoder:
https://youtu.be/wu-1f2CMlmY -
@dbemowsk
I take back what I said earlier. I like the way this guy did it better, because with the gearing you can get even more resolution out of your encoder:
https://youtu.be/wu-1f2CMlmY
