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  1. #1

    Join Date
    Jul 2021
    Posts
    7

    Tormach ATC accuracy

    Hello,

    Recently I made a part that required a precise 1.5mm deep pocket. Due to the shape of the pocket I had to use 3 different tools, a 1/2" CRB 3FL to face the stock down, then a 3/8" and a 1/16" to make the pocket. When I finished the part, the pocket was 1.05mm. I use the Tormach ETS to set everything in Z(tool lengths, work offset, etc), and a Haimer on X/Y.

    I did some repeated tool length tests with the ETS and the same tool in the spindle, and found the ETS to be very repeatable, down to 0.007mm or less.

    Since this looked fine, I then moved on to doing a 'touch off entire tray' which I always do after every REF X/Y/Z before making a part. Here I saw some issues. While mostly repeatable, I saw a few errors where part lengths would come out up to ~0.5mm different, including the tools I was using for the pocket. I assume this could be the source of my error.

    Has anyone experienced this and what level of Z repeatability do you get with your ATC? Is there anything I should check/adjust?

    Thanks in advance.

  2. #2
    Registered
    Join Date
    Aug 2016
    Posts
    118

    Re: Tormach ATC accuracy

    After loading a tool with the ATC, check if there's any gap between the holder and spindle nose. You might need to bring the ATC Z position down a little bit. Or if you've previously crashed the ATC, the tray or forks might be bent.

  3. #3

    Join Date
    Jul 2021
    Posts
    7

    Re: Tormach ATC accuracy

    Thanks for the reply, it looks like you are dead on. I just checked it and it appears both are the case:

    First, I found that any tool I load from the ATC has at least a small gap(I can fit paper in there). Most of them have a very similar gap, however I found at least one that had a larger gap. If I manually removed this tool from the spindle, manually put it back in the spindle(tight against the spindle) and asked the ATC to retrieve it it would stop against the tool holder and not grab it. I assume this means one or more of the forks are bent and need replacing. I also confirmed that if I move that same tool to another fork, then the gap after ATC fetching is different. A while ago we did have problems with the air compressor which caused the spindle to not let go completely of the tool and try to pull it off the ATC breaking the nylon bolts, this might be when the fork got bent although I would expect it to be bent upwards, not downwards.

    Since they all have a small gap, I assume we also have to do a subtle ATC Z adjustment so the spindle face is flush with the tool holder on every tool.

    Thanks again, I'll give this a try and report back, but let me know if there are any other thoughts.

  4. #4

    Join Date
    Mar 2020
    Posts
    183

    Re: Tormach ATC accuracy

    Wow, never would have considered that as a possible source of error and was ready to say that chasing ATC issues was a waste of time until I read foot's response. I was waiting to upgrade to a bt30 spindle before starting my atc build because I was worried about the spindle releasing tools properly and damaging something and now I'm glad I did. I probably would have been chasing my tail for weeks if that happened to me.

  5. #5
    Registered
    Join Date
    Jun 2005
    Posts
    579

    Re: Tormach ATC accuracy

    I had one of the first beta 1100 TTS ATCs and every now and then would need to get in and clean dried coolant and rust from under the forks to keep them all aligned. For super-precision Z work, I'd stop the spindle and 'pop' the tool back into place. I think they changed some things to keep rusting down, but something to look at periodically.

    With BT30 it's less of a thing as the drawbar pulls the tool into the taper.

  6. #6

    Join Date
    Jul 2021
    Posts
    7

    Re: Tormach ATC accuracy

    I took all the forks off to check them, but then I also checked the height of the ATC(the track between the 2 station mounting holes) as the ATC rotates relative to the table with a dial. I found that there is a 0.032" variance as the disc moves around. My understanding is that the ATC Z should be set as the spindle 'just' touches the tool and not provide any additional pressure. If this understanding is correct, then this tilt will be transferred as a Z offset to the tool when it is loaded, so we will need to correct the ATC tilt.

    The tool forks look straight at first glance but we'll have to figure out some way to really confirm that they're not slightly bent. The whole nylon bolt/plastic bushing ATC design seems like it could have more potential slop in it (maybe more likely?) than the forks being bent. It never feels like those nylon bolts are ever tight.

  7. #7

    Join Date
    Jul 2021
    Posts
    7

    Re: Tormach ATC accuracy

    Actually, i'm not sure what I was thinking. Since i'm measuring the ATC disc at one point relative to the table, the 0.032" variance must be in the disc(or the shaft), so ATC tilt is not going to fix that. I guess i'm going to check all the forks and then see if I can apply a slightly lower ATC Z such that it presses a little on the tool, enough to overcome the 0.032"...seems like a fat chance.

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