High Speed Spindle - Drilling & Mild Steel

On Thor I have a 4KW 24K RPM high speed spindle. The torque curve means that generally at lower RPM there is little grunt.

Ive read about some settings on the VFD where it may be possible to increase the performance, at a cost of heat and/or reliability.

For drilling, going to carbide drills, does this allow me the option to drill at 12K rpm?

For mild steel, most of the speeds and feeds are showing 3K RPM max, of course as I increase the speeds I can do more RPM but there is a point that I cant go faster and I am nowhere near the torque curve. Apart from gearing down, is there any other way to deal with mild steel and a Chinese spindle? Different end mills? Adaptive strategies?

Thanks

Mild steel is a bit "gummy" unless you use a leaded variety.
You could use interpolated milling rather than drilling for holes of limited depth?
Have you tried single flute cutters? I know it sounds mad but they are easy to sharpen and I use them on some difficult stainless steel and carbon steel jobs.
Are you using flood coolant?

- Nick

Have you tried a spiral drilling method using a standard endmill ?

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Originally Posted by magicniner

Mild steel is a bit "gummy" unless you use a leaded variety.
You could use interpolated milling rather than drilling for holes of limited depth?
Have you tried single flute cutters? I know it sounds mad but they are easy to sharpen and I use them on some difficult stainless steel and carbon steel jobs.
Are you using flood coolant?

- Nick

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I could do interpolation, just getting a feel for what others do. Not tried single flute mills but willing to try. No flood on this machine (not yet anyways, and trying to avoid it if I can).

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Originally Posted by EddyCurrent

Have you tried a spiral drilling method using a standard endmill ?

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Isnt that the same as 'interpolating'?

Yes I think it is (spiral drill method is CamBam speak)

Quote:

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Originally Posted by EddyCurrent

Yes I think it is

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I think so too :-)

So certainly an option. Getting round holes round is always interesting. That said, if you need accuracy, you could ream afterwards (assuming slightly undersized hole).

Hi Chaz,

This is not what you want to hear but I only spot drill on steel, then over to the drill press to finish off. Chinese spindle is way to fast to use as-is, and when slowed down the torque is too low, as you say.

Or I use the methods above and interpolate with an end mill with plenty of oil. You can certainly hear and feel that it is cutting something tougher than aluminium (on my modest router machine anyway).

For aluminium I pilot drill using a 3mm twist drill at 10,000 rpm and peck to the required depth (occasional dab of lubrication). Then over to the drill press or cordless drill to the final size.

On my new machine under construction I have allowed scope to fit an indirect drive WC spindle through a multi-V pulley gearbox to get the speed down (and torque up).

Quote:

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Originally Posted by routercnc

Hi Chaz,

This is not what you want to hear but I only spot drill on steel, then over to the drill press to finish off. Chinese spindle is way to fast to use as-is, and when slowed down the torque is too low, as you say.

Or I use the methods above and interpolate with an end mill with plenty of oil. You can certainly hear and feel that it is cutting something tougher than aluminium (on my modest router machine anyway).

For aluminium I pilot drill using a 3mm twist drill at 10,000 rpm and peck to the required depth (occasional dab of lubrication). Then over to the drill press or cordless drill to the final size.

On my new machine under construction I have allowed scope to fit an indirect drive WC spindle through a multi-V pulley gearbox to get the speed down (and torque up).

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Tell me more about the WC spindle please.

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Originally Posted by Chaz

Tell me more about the WC spindle please.

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Might have got you excited over nothing. WC just means water cooled Chinese spindle
See my signature mk 4 build post 86 for where I was making sure design would allow for geared spindle drive

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Originally Posted by routercnc

Might have got you excited over nothing. WC just means water cooled Chinese spindle
See my signature mk 4 build post 86 for where I was making sure design would allow for geared spindle drive

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Thanks, noted, checking.

Just read through the thread quickly. I can see the spindle body, lovely. Are you able / willing to share the design please? This is to use R8 / TTS?

Thanks

Quote:

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Originally Posted by Chaz

Just read through the thread quickly. I can see the spindle body, lovely. Are you able / willing to share the design please? This is to use R8 / TTS?

Thanks

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To be clear I'm not planning to build this any time soon. When the new machine is finished I'll run with the spindle direct and see how it goes. Significant stiffness increase should allow me to do much more than current machine.
But the indirect drive version of the spindle does indeed use the R8/TTS combo with tools changed manually via the draw bar. But I basically threw this together to make sure when the time comes I had space to do the upgrade. Not worked out pulley reduction and the speeds I might want or gone deeply into bearing size and max rpm or looked at any optimisation of parts.
I'll see if I can output a few of the key parts (bearings housing spindle drawbar) to give you a start point if you are ok with it on that basis. I don't know if this will work but has the right features. You need to think about hardening and grinding of the taper and possibly bearing journals unless you want to make a demo part first
I can do iges format which most cad programmes can read. Away from machine so give me a day or so.
If you use it and develop and build something please post it up as you'll probably get there before me ! Thanks

Ps with a bit of work a PDB can be added to give quick changes. I won't go this far but ATC is then possible if you want to add that as well

Quote:

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Originally Posted by routercnc

To be clear I'm not planning to build this any time soon. When the new machine is finished I'll run with the spindle direct and see how it goes. Significant stiffness increase should allow me to do much more than current machine.
But the indirect drive version of the spindle does indeed use the R8/TTS combo with tools changed manually via the draw bar. But I basically threw this together to make sure when the time comes I had space to do the upgrade. Not worked out pulley reduction and the speeds I might want or gone deeply into bearing size and max rpm or looked at any optimisation of parts.
I'll see if I can output a few of the key parts (bearings housing spindle drawbar) to give you a start point if you are ok with it on that basis. I don't know if this will work but has the right features. You need to think about hardening and grinding of the taper and possibly bearing journals unless you want to make a demo part first
I can do iges format which most cad programmes can read. Away from machine so give me a day or so.
If you use it and develop and build something please post it up as you'll probably get there before me ! Thanks

Ps with a bit of work a PDB can be added to give quick changes. I won't go this far but ATC is then possible if you want to add that as well

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Thanks, anything appreciated. I can open all formats with Fusion 360, so happy to look at the design. Might be worth doing something together? Im tempted to get something working that can be used by many.

I see at least some one is making lower RPM spindle in the standard 80mm mounts compatible with standard VFD's

https://www.youtube.com/watch?v=T-F_xZHEWDU

I'm surprised the Chinese aren't already all over it.

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Originally Posted by Desertboy

I see at least some one is making lower RPM spindle in the standard 80mm mounts compatible with standard VFD's

https://www.youtube.com/watch?v=T-F_xZHEWDU

I'm surprised the Chinese aren't already all over it.

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I cant see how its done. Some form of gearbox on the front of the spindle?

Quote:

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Originally Posted by Desertboy

I see at least some one is making lower RPM spindle in the standard 80mm mounts compatible with standard VFD's

https://www.youtube.com/watch?v=T-F_xZHEWDU

I'm surprised the Chinese aren't already all over it.

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I can hear why they've disabled comments for the video ;-)

Chaz,

For info in case you missed it, TTS/R8 new thread posted here:
http://www.mycncuk.com/threads/11138...3218#post93218

Thanks

Quote:

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Originally Posted by routercnc

Chaz,

For info in case you missed it, TTS/R8 new thread posted here:
http://www.mycncuk.com/threads/11138...3218#post93218

Thanks

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Thanks, checking.

Quote:

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Originally Posted by Desertboy

I see at least some one is making lower RPM spindle in the standard 80mm mounts compatible with standard VFD's

https://www.youtube.com/watch?v=T-F_xZHEWDU

I'm surprised the Chinese aren't already all over it.

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It's made in China, just like every other round spindle.
If you download the "manual", it's only 6.4 amps, so it's power is actually less than most 1.5Kw spindles.

Just another company self-proclaiming to be CNC experts.

You could​ probably get a lot more torque on low rpm by using proper vector vfd. I dont know if chinese make any, oh and I have seen limit for vector use of vfd on max 200hz, so its worth checking into that before you spend bunch of money. BTW vector vfd is usualy more complicated to parameter properly, but with WC spindle you should have plenty of torque on low rpm. all of this is without hands on on chinese spindle so I take no responsibility for bad advice [emoji23]

Poslano sa mog MI 5 koristeći Tapatalk

correction, you would need sensorless vector vfd

Poslano sa mog MI 5 koristeći Tapatalk

I wonder how well these work?

https://www.shop-apt.co.uk/carbide-e...SABEgIunvD_BwE