[pakirk]

Advice please
Hi I have an X3 CNC mill for almost 4 years now. I am not that experienced milling different materials. 95% of the time I use it for plastic sheet (mainly High impact polystyrene), PCB Etching and sometimes Aluminium and sometimes free cut mild steel. I would also like to try some 3D milling in wood.
Some of the jobs I do take 3 hours+ and to get a nice cut using 1 to 3mm end mill at max speed (2000 RPM could do with being faster). There are three issues,
1. The gearing in the head is very noisy.
2. The stock motor gets hot so I have to do my cuts is stages to allow for cooling.
3. 2000 RPM is not quite fast enough for plastic sheet, Not fast enough for PCB etching.
I was thinking of making a new head using a 3phase ER20 High Speed Spindle and Fuji Frenic Mini - Single Phase Inverter.
High Speed Spindles, Motors & Inverters - Arc Euro Trade
Unfortunately the data sheets are a bit limated
I have a few questions.
Any idea what the lowest speed can be?
Is this going to be quieter?
Is this over kill for what I do?
Will this spindle run slow enough to not melt plastic say 3000 RPM?
Will it have enough power to mill metal at low speeds?
Can I control the spindle speed from Mach3 with this invertor.
Am I better off getting a nice 3 phase motor and invertor and modify the original head to timing belt drive?

Any advice would be appreciated
Thanks
Anthony

[Big Daddy]

Well working within your means you might try using cutters with more flutes. With only 2,000 rpm to work with, I'd recommend using a 6 flute cutter but running your machine no higher then 1,875 rpm. Plus plug in a fan and point it at the motor to help keep it cooler. 5's (5 flute) work great but they need a little more rpm (outside of your machines ability) at the higher feed rates & get a decent surface finish (above a 64 RMS). If you plan your cut steps & depths keeping them within what is considered, "the standard" for that cutters diameter you should also realize an increase in your feed rates apposed to what you were use to seeing believe it or not.

[Bob La Londe]

If high precision is not a must (runout of a thousandth or two), why not make a clamp to mount a wood router or other high speed spindle to the side of your quill? Even guys with big bad mills use this trick for getting more out material removal out of small cutters. I use cutters from .125 down to .03125 (smaller than 1mm) all the time in a wood router. In fact I have two table top mini mills both running wood routers as their primary spindle. (The stock spindle was removed and set aside.)

Oops. Missed part. You can use that high speed VFD driven spindle the same way. A clamp your quill for offside mounting.

For the smallest cutters there really isn't anyway to boost production except by increasing RPM. Bear in mind cooling will become a huge issue when you are spinng 24000 rpm. I favor flood coolant, but some guys report good results with spray mist coolant.

Bobby Warfield assembled a few different secondary spindle mount pictures here on this page: Even if one doesn't suit your needs exactly I bet one will give you an idea.

http://www.cnccookbook.com/CCHighSpeedSpindleAddOn.htm

[WOTDesigns]

Check out a simple 5600rpm mod. I run it at 4000rpm daily, but on long runs I bump it down to 3000rpm. Note my mention of pricing in new spindle and bearings that should allow 5000rpm constant. I'm planning on changing spindle later this year to add new bearings without the hassle and months of fighting everyone seems to go through trying to get the old ones off.

https://www.youtube.com/watch?v=JGo6...e_gdata_player

[Bob La Londe]

Oops... missed the questions. Typically those high speed 3 phase spindles that peak at 24000 are rated at a minimum of 8000. I think that is one of the man reasons many use them as offside spindles instead of primary spindles. They want to still have their stock slow speed spindle for hogging out steel.

[WOTDesigns]

Another option (the best for a small table travel mill) is to watch ebay for an Air Turbine Pnuematic Spindle. I recently sold one for $1300. Still have one I use. its a lot of money, but its 40K constant rpm, repeatable height, very quiet, only needs around 6cfm of air. I put a tts collar on mine and keep an engraver in it most of the time. Engraving aluminum at 30ipm (theoretical) is scary at first but NICE to do. Lets me run .032" em in aluminum at over 30ipm too.

[pakirk]

Thank you all for your replys. A lot to think about.

I am still considering a nice 3 phase motor to replace the stock motor. The only isue is though looking at Rs conponents they don't have very high RPM.