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Author Topic: Tormach type toolchanger that actually works!  (Read 4776 times)

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Offline comet

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Tormach type toolchanger that actually works!
« on: January 20, 2014, 03:59:16 PM »
After spending many hours designing building and setting up to work like clockwork,a tormach type parallel arbour, carousel changer, can you imagine how I felt when all I had was a poor cnc drilling machine? not good!
  Like many before me (who I chose to ignore) I found that you really cant get enough pressure on the r8 collet to hold the 20 mm (in my case) arbors,to get any where near you have to have to have a huge amount of pressure to release it. the best performance thru. alli was 10mm deep with a 10mm dia cutter anymore than that and the whole arbor pulls itself out of the collet. A well documented problem ! Any more drawbar pressure and it seems like a bomb waiting to go off!!
    So it all languished there hanging of the side of the bf30 gathering dust. This morning it occurred to me that if you put a negative angle on the arbor then the r8 collet will over travel into the negative and not allow the arbour to pull out. A little bit of maths later came out with a 1 degree included angle. Sure enough it locks in a treat plus i bet i haven't got half the pressure on the draw bar now!! Happy days!! ,well till the next "challenge"

Tony

Offline poppabear

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Re: Tormach type toolchanger that actually works!
« Reply #1 on: January 26, 2014, 10:21:04 AM »
NICE SOLUTION!!!  Simplicity is the mark of Genius!!!  Thank you for your solution!
Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/

Offline budman68

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Re: Tormach type toolchanger that actually works!
« Reply #2 on: January 26, 2014, 10:25:05 AM »
So just so I understand, you are increasing the amount of contact between the inside of the collet and the arbor by doing the -1 deg. angle, is that right?

Thanks for taking the time post this-
Dave
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Offline comet

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Re: Tormach type toolchanger that actually works!
« Reply #3 on: January 26, 2014, 10:35:26 AM »
Dave no its nothing to do with contact area,its about in effect "wedging" or locking the arbour into the r8 collet.
at present im using a standard r8 collet but im going to have a play with grinding the collet a teeper angle to ensure it pulls up parallel on both tapers.
although it seems ok as is.

Poppabear thanks for the complement I hope it helps people out

Offline budman68

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Re: Tormach type toolchanger that actually works!
« Reply #4 on: January 26, 2014, 10:51:19 AM »
Oh, ok, I understand now, thanks for that-
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Just because I'm a Global Moderator, don't assume that I know anything !

Dave->    ;)

Offline poppabear

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Re: Tormach type toolchanger that actually works!
« Reply #5 on: January 26, 2014, 11:10:30 AM »
Got a question, How are you getting that taper? Are you using your Lathe, or Grinder attachment on the lathe, if using the grinder
how are you getting to the flange without also grinding into the flange?

Scott
Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/

Offline comet

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Re: Tormach type toolchanger that actually works!
« Reply #6 on: January 26, 2014, 11:32:49 AM »
well the tapers i cut using freshly sharpened carbide cut it a treat.
If you wanted to use a toolpost grinder then you would dress the periphery with about a 5 deg angle and tap the grinder 5 deg off 90. that would give you the clearance.

Tony

Offline comet

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Re: Tormach type toolchanger that actually works!
« Reply #7 on: January 29, 2014, 03:23:20 AM »
OK I have reground the r8 taper on the collet to approx. 17.5 deg (giving it an extra 0.5 deg a side) this is to pull the tapers up parallel in the locked position. This has made another huge difference! I put a 12mm cutter in with not a great amount of drawbar pressure and could push it thru. aluminium at a rate that actually stalled the spindle and still it neither pulled out nor slipped. so I would say that's as good as its going to get for now.

Offline poppabear

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Re: Tormach type toolchanger that actually works!
« Reply #8 on: January 29, 2014, 08:25:57 AM »
Nice!!  can you post a .dxf, or .iges, or .3dm or pdf drawing of a profile view of your holder, with the diminsions, angles/tapers.
Where did you get your tool holders that you are modding?

Thank you for your time, and solving this issue for use that use R-8's with ATC's.

Scott
Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/

Offline comet

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Re: Tormach type toolchanger that actually works!
« Reply #9 on: January 29, 2014, 10:48:11 AM »
I actually make my own arbours either turned or I buy in Chinese 20mm parallel er arbours and then attach a collar to them, that's the cheapest way of doing it.

While im here I have  actually placed a European registered design notice on the double taper lock , I don't mind individuals building there own systems, but would take a dim view of people taking commercial advantage of this Method with out first contacting my company Horton Engineering.