Chinese Spindles

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Originally Posted by Jonathan

It's possible to do ATC without a drawbar:

http://hightechsystemsllc.com/pt_rapid_changer.html

...but with that design I suspect the inherent imbalance of the spring will severely limit the maximum rpm, unless the holders are very small.

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Yes I seem to remember they are 10K limited.?

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Originally Posted by JAZZCNC

The shaft is very strong on the 2.2KW spindle and would easily bore without weakening too much. Obviously it will but to be honest these spindles don't produce enough torque to get anywhere near being able to snap a shaft of this diameter.

I don't think it would be too hard to design some way to draw the ER collet but it would have to be a single large collet permantly installed.
Then separate tool holders machined to actually hold the cutting tools. Similiar to the Tormach system.

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I think i can do the tool holders without to much trouble i made some for my easy change on my Boxford260.

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Originally Posted by JAZZCNC

Problem with this approach, with this spindle, is both the relatively small diameter of the largest ER20 collet @ 13mm and the fact they will need to be balanced to handle the high spindle speeds..

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ahh yes my 260 only managed 3500rpm

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Originally Posted by JAZZCNC

The tormach system works by using the largest R8 collet @20mm and the tool holders shank match's . . BUT . . the main difference and the area I think will be hardest to over come is the balancing. Also because of the relatively small 13mm shank the tool holders will also need to be machined from high quality steel and hardened appropriatly.

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Dooable i think..

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Originally Posted by JAZZCNC

The tormach systems highest spindle speeds are I believe 10K Max. The jump to higher speeds I think is where all the hard work will be.? Getting it wrong will shake the machine and very quickly wear the spindle bearings away, not to mention the shite cutting it will do.

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I did read the 10k speeds of this sytem was due to the spring and holding pressure, but i could be mistaken.

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Originally Posted by JAZZCNC

It's do-able but far from simple.!! . . . . If it was simple and done cheaply our Asian cousins would have surely done it by now don't you think .??

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I think they have....
Attachment 6045
Attachment 6046

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Originally Posted by Ricardoco

I think they have....
Attachment 6045
Attachment 6046

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Yes I know they make them but don't think they will be cheap and that was my point.!! They will be 2K plus I think.?

yup they sure are expensive, but maybe its a demand thing?? maybe...

http://www.ebay.co.uk/itm/ATC-auto-t...item2570ee0e4d

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Originally Posted by Ricardoco

yup they sure are expensive, but maybe its a demand thing?? maybe...

http://www.ebay.co.uk/itm/ATC-auto-t...item2570ee0e4d

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I've got a sneaky feeling that could be Kellingcnc in states.??

What size machine is this going on.?

I have thought for a long time that the BT30 spindle Cartridge that tormach sell as an accessory could easily be made into good ATC.? Again not overly cheap but doo-able.!! Though needs a large strong machine.!

I'm going to enquire with a company I deal with who make,repair, high quality spindles. The stupidly expensive multi KW spindles with ceramic bearings alone costing 1000's but I did wounce mention could they make a cheap ATC cartridge and they said possibly and draw something up and they'd have a look.? . . Never did maybe when I have more time i'll look into it more.?

6'x3' steel frame, as an alternative i could use a chinese spindle geared down 2:1 or similar to drive a spindle cartridge.........

Yourself and others have been helping me decide on its design for a couple of years now lol

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Originally Posted by Ricardoco

6'x3' steel frame, as an alternative i could use a chinese spindle geared down 2:1 or similar to drive a spindle cartridge.........

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I wouldn't because the price of a 3HP 3 phase motor is so much cheaper and give far more torque done to very low RPM. You could gear it up if you need high RPM.
There are loads of 3PH motors in scrap yards and not silly money new.
To be honest I very rarely need over 10-12K but often would like the abilty to go lower than 5K which the WC 2.2KW just can't do and still be usable.!! Honestly these spindles don't have high torque even with a torque vector drive.!

its more a size thing for me the chinese motors themselves are quite compact but if there are alternatives then i would be happy to look at them...