ATC Nylon Bolts

We change a LOT of tools using the ATC. Some may remember the photos of worn TTS tool holder ends I posted. Speculation was that the tool holder were just soft to start with. Checked using our Rockwell Bench Tester however they were all Rc 50+. We just change a LOT of tools.

One problem that has raised it's head now and again is the breaking of the nylon bolts holding the ATC fingers - dropping the tool and stripping the fingers off the tray. After a while inserting new bolts becomes almost as fast as manually changing tools (well maybe not that fast) but it is still a pain in the ass and tends to chip carbide tools. I also noticed that once it started on a particular tool position, it became more frequent. Looking closely during tool change it was apparent that the tool holder was being pushed in and out by the descending spindle due to misalignment. So the tray would be realigned, helped for a while but the problem would return. Finally noticed that the nylon fingers no longer held the tool holder tightly. The offending ones were just worn out. Replaced with new fingers and problem solved.

Attached are photos of two worn fingers and a new finger. You can notice the white stress marks on the finger around the hole for the toolholder and the holder doesn't fit snug in the finger any longer. It has about 1/16" of play.

I think that the worn fingers may be capable of being heated, closed up and rebored to correct size and location. But for now I have just replaced then with new. So far I have replaced 6 of the 10 fingers. Happy to say that once the finger is replaced the problem with breaking bolts at that location goes away.

Hope this helps someone.

gary

Best tool I made for replacing ATC bolts was to knurl a 2" wide x 1/2" thick disk of aluminum, then drill and press a 10mm socket into the center.

I have to check the fingers on mine. A couple positions have dropped tools in the recent past for no particular reason.

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Originally Posted by shred

Best tool I made for replacing ATC bolts was to knurl a 2" wide x 1/2" thick disk of aluminum, then drill and press a 10mm socket into the center.

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I like that idea!

Gary, good post.....Also my exact same experience. The ATC has some parts that simply are prone to wear. The unfortunate part is you find this out at the expensive of ruined cutters and tools and even worst ruined work pieces. Tormach needs to review their costing of these normal maintenance parts and encourage ATC users to periodically inspect and replace, better earlier then after damage.
I believe a better design for the spring finger does exist. The other weakness is the fine line that exists in having the collet open up sufficient to insure alignment of the TTS to the collet but still when retracted have enough grip on the TTS to not spin in the collet under a more heavy cut.

Gary, how long have those fingers been in use? My ATC also gets a lot of use, maybe not as much as yours, but would be good to know for inspection interval.

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Originally Posted by shred

Best tool I made for replacing ATC bolts was to knurl a 2" wide x 1/2" thick disk of aluminum, then drill and press a 10mm socket into the center.

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A ratcheting box end wrench also works well - The Craftsman 10mm I have has just enough offset to clear the front bolt while tightening the rear - there's no angle on the box end like a standard wrench has.

It would be nice if the controller kept track of how many times each tool holder position was involved in a tool change. Then when the screws break or you replace a fork you could record the count and reset it. After a while you get a pretty good idea how many tool changes screws and forks will last and then you could do a preventive replacement once you get beyond ~ 90% of the cycles you have determined.

I am sure it is a bit more complicated than just that. I imagine that a tool holder position dedicated to a 2" face mill will fail in fewer cycles than one with an engraving tool in an ER16 collet. But that could be accounted for.

bob

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Originally Posted by 74BurkeMVN

Gary, how long have those fingers been in use? My ATC also gets a lot of use, maybe not as much as yours, but would be good to know for inspection interval.

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About two and a half to three years. I started replacing them about a year ago. I have also had to replace a couple of the metal fingers, they had a groove worn in them from the holder sliding in and out. There are a couple more that could stand to be changed.gary

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Originally Posted by nitewatchman

About two and a half to three years. I started replacing them about a year ago. I have also had to replace a couple of the metal fingers, they had a groove worn in them from the holder sliding in and out. There are a couple more that could stand to be changed.gary

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Thanks Gary!