VFD Programming Questions

[George Yetka]

Generally speeds and feeds are available from the manufacturer of the bit. My VFD takes input from my cnc which is programed off Vectric software that has AMANAs catalog in it plus it has a generic catalog. I have never really done a warmup with mine. My VFD runs for a while before powering the spindle and the spindle has a soft start in which it takes 15-20 seconds to come up to speed. Once at speed I initiate carve.

[stan kern]

thanks everyone

[Jim Becker]

One other thing...after you calculate your chip load and create your file(s)...when you send it/them to the machine, you need to use your ears. Sometimes varying just a few RPM in either direction results in a better cut. Math is great, but the real world is sometimes a bit more, um...flexible.

[stan kern]

I thought the spindle would run slower than the router as i ran the router at 19k rpm
i find the spindle needs about 10-12k as it sounds better , slower sounds not good
regardless of chip load
i see a lot of people are using 15k
Anyhow i like it

[Michael Burnside]

One other thing...after you calculate your chip load and create your file(s)...when you send it/them to the machine, you need to use your ears. Sometimes varying just a few RPM in either direction results in a better cut. Math is great, but the real world is sometimes a bit more, um...flexible.

Aint that the truth? I have my own program I wrote just because of this. If I input a feed/speed target, it will also give me the over/under as well by +/- 5, 10, 15 percent or I can input the feed target and it will give the over/under for speed or vise versa. Sometimes I'll use the - or + depending on the wood species or if I'm going to be using a bit that only has a few jobs left LOL.

[Jim Becker]

I thought the spindle would run slower than the router as i ran the router at 19k rpm
i find the spindle needs about 10-12k as it sounds better , slower sounds not good
regardless of chip load
i see a lot of people are using 15k
Anyhow i like it

It's a complex thing...the machine's actual average forward cutting speed combined with cutting depth, the design of the tooling plus the RPM and the specific material all come into play. We all get a general feel for what works with our particular machine, spindle, tooling and various materials. With my particular CNC (a Camaster Stinger II) I often run at between 200 and 400 IPM and my RPM is between 12-14K but absolutely varies with the material and nature of the cut. Smaller stuff with a lot of direction changes will never hit the intended cutting speed, so that's going to affect the optimum RPM. Larger profiles where you can "let er rip" will need a commensurate change in RPM to produce a good average chip load for the given material. Etc. It's an art. You learn what works and as I noted, "what sounds good".

[Michael Burnside]

I thought the spindle would run slower than the router as i ran the router at 19k rpm
i find the spindle needs about 10-12k as it sounds better , slower sounds not good
regardless of chip load
i see a lot of people are using 15k
Anyhow i like it

Some spindles can't even go below around 8-9k as their torque curves fall off quite rapidly and maintaining constant speed is difficult. You should check the specs of your spindle and try to be in the sweet spot in the torque curve.

That said, I personally run anywhere from 11k to 15k depending on what I'm doing. Usually in the 12-14k most of the time. That said, I don't think about speed as much as chip load and I don't listen as much as I look. I'm looking for chips, not dust and I'm setting up my feed rate to hit a given target chip load. For everything I've cut I always write down the feed/speed/chip load and over the years I refine those numbers. For example, I can look at my table and for walnut with 1/4" downcut endmill, I'll run at 13.5k RPM at 250 IPM and 1xDiameter DOC, giving me a target chip load of around 0.009. I'll usually measure a few chips after cutting the first batch and if they're close to that, I'm good. If not, I'll tweak it usually +/- 5%.

I use only Rego Fix collets and nuts. Available from MSC. They aren't cheap but honestly I find a hard time "hearing" the difference as they are whisper quiet and runout is basically zero. Even during 18K warmup they're buttery smooth. Be warry of cheap collets as the runout will kill you and make your feed/speed numbers way over/under depending on where the bit is. This is especially true for small bits where even a runout of 0.003 is a huge percentage of your target chip load.

[Wes Grass]

Check out 'Maritool' for ER collets and cutters ... mostly for metal work.

I'll vouch for his Cat tool holders and collets.

[Wes Grass]

I posted a comment about VFD voltage, somewhere... can't find it, maybe hit the wrong button ...

380 volts is 220 volts x Sin 60' = 190 ... or Cos 120' ... same thing. Times 2 ...

[Jim Becker]

Check out 'Maritool' for ER collets and cutters ... mostly for metal work.

I bought additional collets and collet nuts from them...very high quality!

[stan kern]

it all worked out fine, found the programming overwhelming tons of selections but basically looking for rpm voltage and current of the spindle
amazing thing ....10.5 hp spindle running at 4.5 amps

[David Buchhauser]

it all worked out fine, found the programming overwhelming tons of selections but basically looking for rpm voltage and current of the spindle
amazing thing ....10.5 hp spindle running at 4.5 amps

Stan - I assume that 4.5 amps is with no load. What kind of current are you drawing under full load? Just curious.

David

[stan kern]

few quick runs with a 2 flute 1/2 bit and I seeing 5.0 amps so far
but I really have not put it to full test yet
I have been tracingf a diagram and running the shaper origin
Also when I did do a quick test I was cutting 3/4 plywood 7 inch circles and it was running 5.0 amps at a cut of 3/8 deep ---2 passes
I am amazed
I am also still using the 3.25 router (easy switch over)

[Gary Campbell]

I am also still using the 3.25 router (easy switch over)

Why???? (added to get 10 characters)

[George Yetka]

My buddies Haas has a 50hp spindle and it only hits 10000 rpm. I assumed cutting aluminum at extreme speeds would require higher rpm. But no, theres no assumptions in cnc work. Take known quantities and adjust slightly with trial and (skip the error). I buy amana bits and use there catalog in vectrics to set speeds and feeds. I dont do enough work with the cnc to know better or worry about the cost of the amana bits.