How to Figure What Speed to Run the Bit on a Cnc Shark
Speeds, Feeds, RPM and Depth Per Pass. Starting points for wood on a STEPCRAFT CNC System
2 January, 2018 by Stepcraft .Inc, Erick Royer 
Nosotros go a lot of questions from customers asking about the optimal speeds and feeds, RPM and depth per pass for STEPCRAFT machines when working with wood. Similar with many things related to CNC, there is a lot of trial and fault to discover the optimal settings for your given machine, material and bit (cease mill) that you are using. There are speed and feed calculators on the market and online, but many times, they volition over complicate the process, specially when yous are working with wood. In this commodity, I desire to talk about some good starting points that you can use as a basis of making your commencement successful cuts in wood on your STEPCRAFT CNC.
A couple things that we need to go over commencement.
- If yous are using a STEPCRAFT Version 1 machine, then you need to know that y'all maximum feed rate is 30 mm/sec
- If you are using a STEPCRAFT-2 car, then your maximum feed rate is 50 mm/sec
- Note the number of flutes on your finish mill too as the type of flutes (up screw, down spiral, directly, pinch, etc). A 2 flute up screw volition have different settings than a two flute compression or down spiral. So you desire to make note of this, peculiarly if you intend to save the tool information as suggested below.
It is important to know these values and so you practise non ready the software to exceed them – y'all can not force the automobile to go any faster than information technology is capable of.
Also, these values that I am giving below are just a starting bespeak. You lot will have different results depending on the spindle y'all are using, the number of flute in the bit and style of bit.
In the Vectric programs, yous will select a tool from the tool database. The screen will expect like this:
NAME – This is where you can specifically proper noun your tool. I e'er apply the format shown – type of tool (diameter). You lot tin besides add on the blazon of material that this tool is for. You will, over time, figure out the optimal settings for various materials that you use and you could name this tool for that material so you do not have to become through this process each fourth dimension. For instance, I could proper noun this tool "End Mill (0.125″) MDF" and the next time I run MDF I can choose this tool and know my settings are correct.
GEOMETRY – This is where you lot would enter the diameter of the tool and cull "inches" or "mm"
CUTTINGPARAMETERS
- PASSDEPTH – For wood, my rule of thumb is to always make this number i/ii the diameter of the tool. So in this example of a 0.125″ (1/8″) end mill, I set the pass depth to 0.0625″ (1/sixteen″). Depending on the woods you are cut, you might exist able to increase this. Pino, for example, cuts well at 0.125″ (1/8″) deep whereas Oak works well at 0.0625″ (1/xvi″). Notation: As a general dominion, you should not exceed the bore of the tool as it can put undo stress on the auto, spindle and tool. The only exceptions to this would exist for very light material similar cream or Balsa wood.
- STEPOVER – This setting is used in pocketing; when you remove material between vectors. If you recollect of stepover like mowing a lawn. When you make one laissez passer, you slightly overlap the previous pass to ensure that you are not leaving a small-scale strip of grass uncut. Stepover is the same thing, it refers to the amount of overlap there is between passes. twoscore% is the default which is adept for about general pocketing and roughing passes (when etching 3D objects). When making cease passes, you would reduce this number to 10%, specially when using a 1/sixteen″ brawl nose stop manufactory for detail carving. Information technology volition requite y'all the best finish results.
FEEDS AND SPEEDS
- SPINDLE SPEED – If yous are using a STEPCRAFT HF-500 spindle, then this number would control the RPM. If you lot are using a Dremel or a router such as the Dewalt DW611, or a KRESS, and then this number will non have any event on the job. A skillful rule of pollex for RPM (when using the HF500) is to keep the setting at 15,000 rpm or higher for cutting woods. You will have more cutter speed which volition make the tool cut easier and should provide a better finish. There is no reason to run at full speed though. . Doing so just makes the spindle spin excessively fast.
Finding the optimal RPM – Y'all tin listen to the spindle as it is cut. If it sounds like information technology is straining or chattering and then increase the RPM. To make up one's mind if you are spinning too fast, y'all can lower the RPM until you hear information technology bog a little and then increase information technology until in that location is no RPM audio variance while cutting.
- FEED Rate – When cut woods on a STEPCRAFT, I always suggest setting this to 1/2 of the maximum machine feed speed. So for a Version 1 machine, this will be fix to fifteen mm/sec and for a version 2 machine, you lot will set this to 25 mm/sec. Once the job is running you can increase this feed charge per unit by adjusting theF deedin UCCNC. When you attain 200% you volition be at full speed of the car.
Finding the optimal Feed Charge per unit – I always first a job then listen to the spindle and the scrap. I desire to mind for chatter on the bit or straining on the spindle. If you lot hear either, then lower theF act in UCCNC until it sounds meliorate. If it sounds effortless so you can increment the feed rate until you hear whatever signs of straining or chatter. Once you lot reach 200%, you are at the full speed capacity of the motorcar. If yous reach this and it notwithstanding sounds effortless, then you can become dorsum into the tool settings for this material and increment the depth per cut, leaving the feed charge per unit at 25 mm/sec. Then you lot would commencement the process all over with the new depth per cut.
As an example, if I made it to 200% at 0.0625″ (one/16″) and information technology sounded good, then I would increase my Pass Depth to 0.125″ (1/viii″) and try cutting that material again. I would continue to adapt the speed until it sounds like it is straining then back off ten%. So if I was able to become to 150% before I noticed any strain, then I will go dorsum into the tool settings and change the speed to 37 mm/sec and rename that tool for that material. So the time I cutting that aforementioned textile I can just choose that tool and these setting are optimized (providing I am using the same tool with the aforementioned number of flutes).
Equally a final rule of thumb, I try not to run the machine past 45 mm/sec. The stepper motors volition have more torque at lower speeds and running at max speed tin can increase the changes that you lose steps during a task if, for instance, you run through a knot in the woods which will be harder to cutting. Lower feed rates will take more torque.
PLUNGE Charge per unit – This is the speed at which the bit enters the woods. Keep in mind that End Mills are meant to cutting from the side whereas drills are meant to cut vertically. Y'all tin not plunge an stop factory into material like you would a drill flake. For most wood, I unremarkably set the Plunge Charge per unit to 10 mm/sec or less. Withal if I use a Ramp of at least one inch, I can increase this. We volition discuss Ramps in another post. For now, the best rule of thumb is to keep this at 10 or less.
SUMMARY
If you use this every bit a guide as you lot cut and carve wood materials on your STEPCRAFT, you will find the process much simpler to find the optimal cutting speeds. If y'all have any further questions, please leave a annotate on this post or email u.s. at [email protected]
Stepcraft .Inc, Erick Royer 2 January, 2018
Source: https://www.stepcraft.us/blog/stepcraft-blog-6/speeds-feeds-rpm-and-depth-per-pass-starting-points-for-wood-on-a-stepcraft-cnc-system-4
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