Hi John and others.
If your cutting out the profile of a PCB use "fish tial" cutters rather than standard flute cutters they will last a lot longer, the glass fibres are not very edge friendly and soon blunt fluted cutters where as fish tails go on and on. Also if you have a bit of z adjustment you can vary where you cut on the cutter, and as standard PCB's are 1.6mm thick and a 2mm cutter has about a 20mm cutting edge you can make them last.
One of the first CNC machines I used was based on stepper motors, these tend to have no positional feedback and rely on counting the steps fed to the motors to give an feedback of position. The only problem was if you try to cut to much in one pass the motor can miss steps as it judders so it looses steps, so light multiple cuts are better, also puts less strain on cutter and gives a better finnish. For the best finish cut out just slightley larger than you required finished dimension then do a final finish cut with a higher rpm taking of the last half millimeter or less if accuracy allows, especially if cutting plywood as the top layers can tear easily, MDF is a doodle to machine, though the dust is terrible if you dont control it.
Must admit though having even a 2.5 axis CNC makes it so much easier, both my projects where helped greatly by the fact I could machine accurate templates that I then used for my router.
If your cutting out the profile of a PCB use "fish tial" cutters rather than standard flute cutters they will last a lot longer, the glass fibres are not very edge friendly and soon blunt fluted cutters where as fish tails go on and on. Also if you have a bit of z adjustment you can vary where you cut on the cutter, and as standard PCB's are 1.6mm thick and a 2mm cutter has about a 20mm cutting edge you can make them last.
One of the first CNC machines I used was based on stepper motors, these tend to have no positional feedback and rely on counting the steps fed to the motors to give an feedback of position. The only problem was if you try to cut to much in one pass the motor can miss steps as it judders so it looses steps, so light multiple cuts are better, also puts less strain on cutter and gives a better finnish. For the best finish cut out just slightley larger than you required finished dimension then do a final finish cut with a higher rpm taking of the last half millimeter or less if accuracy allows, especially if cutting plywood as the top layers can tear easily, MDF is a doodle to machine, though the dust is terrible if you dont control it.
Must admit though having even a 2.5 axis CNC makes it so much easier, both my projects where helped greatly by the fact I could machine accurate templates that I then used for my router.
I can't believe nobody is biting ...
I blame it all on you anyway Bas, it was a passing reference in one of your posts a while back that started me down this dark road
This is my plan - build something cheap and nasty with the tools on hand and then use that to cut parts for machine #2. This is the usual path for those who build a CNC machine and do not have access to, or do not want to pay for CNC machining services.
I got as far as finishing the 3 axis and need to mount my motors, but the controller is complete and tested successfully and then I need to mount the router. Unfortunately, more home improvement projects are taking priority currently.
I blame it all on you anyway Bas, it was a passing reference in one of your posts a while back that started me down this dark road
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An externally hosted image should be here but it was not working when we last tested it.
This is my plan - build something cheap and nasty with the tools on hand and then use that to cut parts for machine #2. This is the usual path for those who build a CNC machine and do not have access to, or do not want to pay for CNC machining services.
I got as far as finishing the 3 axis and need to mount my motors, but the controller is complete and tested successfully and then I need to mount the router. Unfortunately, more home improvement projects are taking priority currently.
... or get this one:
http://www.elektor.com/magazines/2008/june/profiler-update.495053.lynkx
or this one:
http://www.elektor.com/magazines/2001/march/pcb-drilling-machine-(1).54404.lynkx
Jan Didden
http://www.elektor.com/magazines/2008/june/profiler-update.495053.lynkx
or this one:
http://www.elektor.com/magazines/2001/march/pcb-drilling-machine-(1).54404.lynkx
Jan Didden
Don't worry about me Bas, with all these unfinished projects in front of me, I'm as good as banned, as I don't have as much time to hang out here it seems.This is my progression, or spiral into the abyss may be a better description.
I started building FirstWatt F5, but I have modified FE126 from Dave to build into FrugalHorns to test the F5 with (and the F4 I already built), but to build the FH, I wanted CNC machined cabinets ... so I needed to build a CNC machine
I'm building a patio in the backyard right now though, so the CNC-FH-F5 will all have to wait
I promise to post any pics when (and if) I ever get this machine finished
BTW, my machine is based on a design called the JGRO (cnczone.com forum). I have the controller boards stuffed and tested (of course, the electronics part was not going to be the stumbling block) and a Bosch Colt laminate router ready to use as my spindle. I'm using 3/8" threaded rod for now.
I'm probably into the project for $400 now, $150 for the stepper motors, $90 for the stepper drive board, $120 for the router and then miscellaneous parts like the bearings (ebay), wood, EMT tubing and fasteners.
If nothing else, I've learned that I like delrin/acetal better than aluminum and plan on using it for building amps and cases in the future.
If it hasn't been said already
CAD CAM EDM DRO Yahoo group
This is essentially the only link you'll need for everything DIY CNC
CAD CAM EDM DRO Yahoo group
This is essentially the only link you'll need for everything DIY CNC
That depends on your definition of precision.
The majority of industrial CNC mills will do something around 0.01mm.
That isn't set so much by the resolution of the electronic and drive system, but by vibration and thermal distortion of the motion system. Steel expands and contracts a lot. Co-ordinate measuring systems use granite specifically due to it's lower thermal coefficient.
To realiably get 0.01mm and lower, you need to start with temperature controlled rooms, lead screws with coolant running through them, temperature controlled spindles.
To DIY a CNC machine and get high accuracy, you'll need to use things like linear rails.
This is probably the finest example of a precision home made CNC machine I've seen
Really, it's best to buy a used commercial machine if that's your goal.
Taig desktop mill
Sherline desktop mill
Alternatively, you can get the bigger, used industrial machines for a one to a few thousand depending on how nice they are. You'll need to set aside some significant space for them though.
People have done some very impressive work on machines like the Taig and Sherline for the expense of some creative thought as to work fixing and so on.
The majority of industrial CNC mills will do something around 0.01mm.
That isn't set so much by the resolution of the electronic and drive system, but by vibration and thermal distortion of the motion system. Steel expands and contracts a lot. Co-ordinate measuring systems use granite specifically due to it's lower thermal coefficient.
To realiably get 0.01mm and lower, you need to start with temperature controlled rooms, lead screws with coolant running through them, temperature controlled spindles.
To DIY a CNC machine and get high accuracy, you'll need to use things like linear rails.
This is probably the finest example of a precision home made CNC machine I've seen
Really, it's best to buy a used commercial machine if that's your goal.
Taig desktop mill
Sherline desktop mill
Alternatively, you can get the bigger, used industrial machines for a one to a few thousand depending on how nice they are. You'll need to set aside some significant space for them though.
People have done some very impressive work on machines like the Taig and Sherline for the expense of some creative thought as to work fixing and so on.
Little late noticing this thread, but this site should be very useful: http://www.cnczone.com/forums/
Check out the DIY-CNC Router Table Machines section of the Woodworking Machines forum.
The JGRO and Joes CNC machines are both highly respected, though if you wanted to go completely over the top, try this: http://www.mechmate.com/
Check out the DIY-CNC Router Table Machines section of the Woodworking Machines forum.
The JGRO and Joes CNC machines are both highly respected, though if you wanted to go completely over the top, try this: http://www.mechmate.com/
Oops! Hadn't spotted that Claus had already mailed a cnczone link. Anyway, it's well worth your time.
DIY MDF machines are perfectly acceptable, though obviously the cutting speeds and accuracies won't be that great.
I'm running a hobbyist aluminium machine, that'll do 1/4" deep, 1/4" wide cuts in MDF at around 120 inches per minute (ipm).
Some of the stuff being discussed by the pros on that board (mainly steel construction) are knocking out 3/4" deep, 1/2" wide cuts at over 400ipm!
CNC is very much a case of more money = faster cutting.
DIY MDF machines are perfectly acceptable, though obviously the cutting speeds and accuracies won't be that great.
I'm running a hobbyist aluminium machine, that'll do 1/4" deep, 1/4" wide cuts in MDF at around 120 inches per minute (ipm).
Some of the stuff being discussed by the pros on that board (mainly steel construction) are knocking out 3/4" deep, 1/2" wide cuts at over 400ipm!
CNC is very much a case of more money = faster cutting.
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