automatic toolchanger teardown

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dugenou
Posts: 3
Joined: Mon 08 May , 2017 14:21 pm
Hardware/Software: Easiturn CNC 3

automatic toolchanger teardown

Post by dugenou » Mon 08 May , 2017 14:55 pm

Hi all,
I'm having some problems with my auto tool changer (it's apparently the same model as on the Orac) and decided to have a look inside. Initially I hadn't looked at the Orac parts diagrams already posted here.

so it was a bit of trial and error to get this thing disassembled. Also, there are some minor differences between my unit and the one illustrated.
Here are the steps I used, I figured it might help someone :

You'll need a bunch of metric hex wrenches; 4mm, 5mm and some other small sizes that I forget for the motor gearbox, and the PCB underneath. Also a custom spanner / pin wrench like this :
IMG_8968_crop.jpg
custom spanner
IMG_8968_crop.jpg (94.24 KiB) Viewed 9822 times
0- make sure ATC is stopped & locked at a valid position

1- (no pic) unscrew the ATC from the saddle, tilt it on its side to reveal the bottom access panel and electricals. Remove / disconnect wiring and PCB.

2- remove the motor + gearbox + heatsink (IIRC it can be removed as one piece); I don't recommend removing the motor from the heatsink unless necessary.
IMG_8966_crop.jpg
motor separated
IMG_8966_crop.jpg (124.6 KiB) Viewed 9822 times
3- Open ATC rear panel; trace a witness mark on the ATC body and the index wheel. Remove index wheel (be careful with the shiny traces on the other side !)
IMG_8967.jpg
index wheel
IMG_8967.jpg (86.21 KiB) Viewed 9822 times
4- with custom wrench, remove locknut (unbending some lock washer tabs may be necessary)
IMG_8969.jpg
lock nut
IMG_8969.jpg (69.65 KiB) Viewed 9822 times
5- remove worm gear side cover
IMG_8970.jpg
worm gear side cover
IMG_8970.jpg (69.95 KiB) Viewed 9822 times
6- push out worm gear shaft; turning the tool holder face with one hand can be helpful
IMG_8971.jpg
worm gear
IMG_8971.jpg (83.57 KiB) Viewed 9822 times
7- holder face : remove plastic caps if necessary; remove 3 bolts.
Note, the 3 other holes have dowel pins in them. On my ATC, two of the dowel pins had snapped flush at the holder face / ATC shaft mating interface. These pics were taken after the whole ordeal of welding a washer + nut, and pulling with a slide hammer / vise-grip combo.
IMG_8973.jpg
holder face
IMG_8973.jpg (104.88 KiB) Viewed 9822 times
8- take one of those bolts (or any M6 bolt) and thread into the middle hole. This should push out the holder face from the ATC shaft.
IMG_8974.jpg
holder face 2
IMG_8974.jpg (101.05 KiB) Viewed 9822 times
9- note the ratcheting mechanism. Very simple; almost effective, but not super repeatable and accurate. And hell to put back together after taking it apart.
The mangled face of the ATC shaft is due to an angry afternoon of failed attempts at removing the snapped dowel pins.
IMG_8975.jpg
ratchet
IMG_8975.jpg (101.63 KiB) Viewed 9822 times
10A (preferred): unscrew ratchet ajuster fully out, and fit a random object (here a flat blade screwdriver) to ensure the pawl clears the bearing outer race, otherwise it's going to be very difficult to push the shaft out. I know, I tried !
IMG_8977.jpg
pry ratchet
IMG_8977.jpg (111.39 KiB) Viewed 9822 times
10B (alternate) : remove ratchet spring guide screw, convince the pawl to exit its groove without throwing the spring into orbit (or into an eye). Good luck putting it back together !

11 with the ratchet pawl taken care of (either out of the way (10A), or removed (10B)) : push out the ATC shaft from the back. A bit of persuasion may be required; a small hammer and a piece of wood used as a drift punch works fine.
IMG_8978.jpg
shaft assy
IMG_8978.jpg (69.7 KiB) Viewed 9822 times
12 tadaaa. Actually I cheated; the ATC shaft assembly really looked like this on mine !
20151002_152115c.jpg
dirty shaft
20151002_152115c.jpg (103.69 KiB) Viewed 9822 times

Here's the original ratchet pawl. This was causing massive issues - shitty repeatability, impossible height adjustment, etc. Also I noticed that every ratchet tooth face is worn slightly differently. I'm not sure what I'm going to do to fix this...
IMG_8979.jpg
ratchet pawls
IMG_8979.jpg (83.6 KiB) Viewed 9822 times

fgc
Posts: 7
Joined: Fri 22 Jun , 2012 6:01 am
Hardware/Software: Looking to purchase Denford machines in the near future

Re: automatic toolchanger teardown

Post by fgc » Mon 31 Jul , 2017 4:49 am

Thanks so much for sharing your teardown! This is very useful when it comes time for me to refresh my old Orac. I really appreciate the effort and time you spent sharing these photos. Please post updates and any tips on reassembly or adjustments you found along the way.

Thanks!

dugenou
Posts: 3
Joined: Mon 08 May , 2017 14:21 pm
Hardware/Software: Easiturn CNC 3

Re: automatic toolchanger teardown

Post by dugenou » Tue 01 Aug , 2017 14:31 pm

fgc wrote:I really appreciate the effort and time you spent sharing these photos. Please post updates and any tips on reassembly or adjustments you found along the way.
Thanks!
You're welcome - glad it could be useful to at least someone. As for reassembly / adjustments, I'm not sure when,how, and if that's even going to happen. As I mentioned, the ratchet stops are worn unevenly, which means that no matter how I adjust it, each tool position will have a slightly different height above centerline...

Also, and more importantly, the motor itself is mostly useless now -- the flimsy brushes held in place by the cheap plastic endcap were sometimes not making contact, which ruined a few parts and carbide inserts too many. And repairing that part of the motor proved to be just about impossible. I was quite unimpressed by the build quality of this swiss-made Maxon motor... and it must not have been cheap, either.

fgc
Posts: 7
Joined: Fri 22 Jun , 2012 6:01 am
Hardware/Software: Looking to purchase Denford machines in the near future

Re: automatic toolchanger teardown

Post by fgc » Mon 07 Aug , 2017 18:43 pm

oh I see. Thanks for explaining. I will keep a lookout for these areas of wear for mine as well.

Thanks again.

TDIPower
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Re: automatic toolchanger teardown

Post by TDIPower » Mon 07 Aug , 2017 21:59 pm

Hi, re the motor, I did a strip on the ATC in my Starturn 5 which had a gear strip. viewtopic.php?f=46&t=4591 I'm pretty sure that the motors were available too individually or as assembled on the gearbox.

Have you thought about either filing/machining the ratchet to the same lower level or building it up with weld and machining back to correct height?

Hope that helps

Pete

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