Extruder stepper rpm speed

Hello,

I'm new with all this 3d printing stuff but have several cnc machines. I want to put together a extruder head and install it on my cnc to create some parts. The cnc is 3-axis, very accurate and rapids at over 1000 inches per minute. Making the extruder head is no problem for me. I can easily machine one out. I also have a couple of spare gecko stepper drivers I can use to drive the extruder motor. My question is how fast does the extruder stepper motor need to run when extruding the ABS? What is the RPM range?
I have a nice geared head high torque stepper motor that I plan to use but it only runs about 40rpm. Any faster the torque drops off to much.

Thanks.

40rpm should be fine even when geared down 5:1 geared down. I would look for wades extruder types. look into hobbled bolt for gripping feedstock, get a nozzle probably 0.5mm to start, and 0.35 for later on. sounds like your machine has the stiffness for high resolution detail.

want to drive people crazy here with inches? most of reprap software/hardware/ and thinking is done in mm. if you want everything to go smooth for you, switch your equipment settings to use mm.

also anther issue is drag. 3d printing with reprap process is low impact. the extruder is always touching filament. 1000 ipm rapids will diminish when head is dragging on something.

also max speed is less important than acceleration. you want acceleration that ramps up within 1mm to 5mm. repeatably. for infill and lines, which quite often are less than 10mm.

Ok thanks just wasn't sure how fast the filament needs to feed even when printing at high speeds. The cnc is a servo driven router, thk linear rails running MACH3. It has decent acceleration but not as fast as some of the 3d printers I see on YouTube. I could increase the acceleration if i needed to. I think it already runs scary fast as is!!!

I was at maker Faire Detroit in July and saw a 3d printer running MACH3. This gave me the idea to make a extruder head and stick it on my cnc. The demo he showed seemed to work pretty good. Nice guy and spent time explaining what programs to use to create the g-code so it will be compatible to MACH3. I already have a arduino PID temperature controller from a previous project that I can use to monitor the extruder.

I'll probably end up making dedicated 3d printer this winter since I have a bunch of linear rails, stepper/servo motor drivers and arduinos not being used. I also have a cnc metal bench mill and manual metal lathe that I can make some parts with.

Thanks again.