Hello Guest it is July 17, 2019, 11:13:38 AM

Author Topic: BT30 spindle from scratch - with power drawbar and ATC of course  (Read 401844 times)

0 Members and 1 Guest are viewing this topic.

Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #480 on: February 03, 2013, 07:12:39 PM »


My second ATC (still TTS, but could very easily accommodate 30-taper with pretty minor changes)

This will be quite a challenge, I would think.  Your TTS based design does not seem capable of gripping a stud. You must have something up your sleeve again.


Obviously the drawbar would have to be changed, but once that's done it should work.  Although, I could forego pullstuds and just use a screwed-in drawbar, as it it now.  I'd grab the toolholders by the groove, basically as I do now with TTS.  The carousel disk and spring "forks" would have to change, as would the fork on the transfer arm, but those are all simple changes.  I think it could be done by changing only about a half-dozen parts, and perhaps changing the "lift" travel.

I'm up to my eyeballs in KFlop stuff at the moment.  I've made quite a few improvements to my controller app recently, and I'm now doing some re-wiring in my E-Box, to clean things up.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

*
  •  1,374 1,374
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #481 on: February 04, 2013, 06:42:38 AM »
To Anyone:  

- How important would it be to have a manual (pendant or equiv) method of operating the ATC? In practical terms, the carousel has to be loaded with tools and so on. My thinking is that inputting a tool change into the MDI is adequate, but it would be good to know if there are any 'wish list' methods that people would like to have, and/or to know what 'real' ATCs provide in terms of manual operation.  

- How important would it be to have the ATC perform some type of automatic tool touch off?  It would be good to get a discussion going on how this works on machines that have it, and how it might be implemented. I saw one that appeared to use lasers.


To Ray:

- You originally mentioned that you were keeping the Geneva for the carousel in your new design, but your latest description says 'servo' powered.  Are you using that term generically, as in 'motors' (i.e. steppers) or have you come over to the dark side?

- In *easily converting your new ATC to work with 30 tapers, how do you accommodate the drive dogs?

*you always say everything is 'easy'. Flying is easy for a duck. It is a bit of a challenge for a donkey. Depends on how you're equipped, I would say . . .  ;)

Offline derek

*
  •  201 201
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #482 on: February 04, 2013, 07:03:41 AM »
On My ATC the carousel is the C axis. I jog the axis and load the tools by hand and then do  MDI sending the C to 0 which is tool 1. I started doing it this way until I could do a custom screen set but found it was easy to do so I'll probably continue to use this method.

I don't have a tool setter on the mill. I have one on the router and it's quite accurate. On the mill it's no big deal for me to touch off manually in one way or another so I'll probably stick with that. The BT30 seems to have good repeatability so I don't envision me ever touching off after every tool change.

Just finished a run of 380 pieces. More than 400 tool changes over a 6 day period without a single miss. Without a doubt the ATC has been some of the best time and money I've spent on the mill since the original conversion. The newness has worn off and I don't even pay any attention to it anymore. It just chugs along making me money!

Derek

Offline simpson36

*
  •  1,374 1,374
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #483 on: February 04, 2013, 07:04:28 AM »
Question on rotating mill head::

I have noted that Bridgeport's CNC mill has a non rotating head as does the Smithy CNC bench mill and others. Years ago when I had a shop with manual mills it was not uncommon to have the heads turned this way and that, but I have yet to ever rotate the head on any of my CNC mills.

Unless the rotation is actually an axis under CNC control, I have some difficulty seeing a justification for it.  While I think it would be beneficial to build in some kind of tramming 'assist', I am leaning toward having the head NOT rotate, per se.  :-\

Thoughts on this?


Thanks in advance,

Offline simpson36

*
  •  1,374 1,374
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #484 on: February 04, 2013, 07:08:10 AM »
On My ATC the carousel is the C axis. I jog the axis and load the tools by hand and then do  MDI sending the C to 0 which is tool 1. I started doing it this way until I could do a custom screen set but found it was easy to do so I'll probably continue to use this method.

I don't have a tool setter on the mill. I have one on the router and it's quite accurate. On the mill it's no big deal for me to touch off manually in one way or another so I'll probably stick with that. The BT30 seems to have good repeatability so I don't envision me ever touching off after every tool change.

Just finished a run of 380 pieces. More than 400 tool changes over a 6 day period without a single miss. Without a doubt the ATC has been some of the best time and money I've spent on the mill since the original conversion. The newness has worn off and I don't even pay any attention to it anymore. It just chugs along making me money!

Derek


Good info. Thanks, Derek!

Offline derek

*
  •  201 201
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #485 on: February 04, 2013, 07:08:45 AM »
The only time I rotate my head is to set the tram. There have been times when I wish it was fixed.
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #486 on: February 04, 2013, 10:08:29 AM »
To Anyone: 

- How important would it be to have a manual (pendant or equiv) method of operating the ATC? In practical terms, the carousel has to be loaded with tools and so on. My thinking is that inputting a tool change into the MDI is adequate, but it would be good to know if there are any 'wish list' methods that people would like to have, and/or to know what 'real' ATCs provide in terms of manual operation. 

- How important would it be to have the ATC perform some type of automatic tool touch off?  It would be good to get a discussion going on how this works on machines that have it, and how it might be implemented. I saw one that appeared to use lasers.


To Ray:

- You originally mentioned that you were keeping the Geneva for the carousel in your new design, but your latest description says 'servo' powered.  Are you using that term generically, as in 'motors' (i.e. steppers) or have you come over to the dark side?

- In *easily converting your new ATC to work with 30 tapers, how do you accommodate the drive dogs?

*you always say everything is 'easy'. Flying is easy for a duck. It is a bit of a challenge for a donkey. Depends on how you're equipped, I would say . . .  ;)


Steve,

FWIW - On mine, I will provide a macro or modified screenset to "assist" the user in loading tools.  It will sequence through the slots, bringing the transfer arm to the forward position so the user can put the tool into it, then it will put it in the carousel.  On my current one, I added buttons to rotate and home the carousel to facilitate manual loading/unloading of tools.

I also plan to have a macro that will automatically touch off all loaded tools (I can tell which slots are occupied, and which are not), and load the tool table automatically.  I think that will be a nice convenience, and time-saver.

I kept the Geneva, though I switched from an external Geneva to an internal, for a much smoother motion profile.  It is driven by a real servo motor, with encoder, mostly just because it was convenient, and only a very few $ more expensive (<$5 more) than the plain gearmotor I used on the first one.

When/If I do 30-taper, the tool "forks" on the carousel and transfer arm will have locating tabs for the drive dogs, to maintain proper orientation.  The spindle will be either servo-driven, or I will provide some simple indexing mechanism.  Indexing is already designed into the PDB for the target machines with 3-phase spindles.

The one rule that I have used my entire career is "If it's complicated, you haven't done it right".  I never start building something until I've gone through enough iterations of the design that I am convinced it is about as simple as it can be.  This approach has *always* paid off, and has allowed me to consistently do things in short order others told me I'd never be able to do at all.  I spend much more time thinking about designs, and much less time actually building them.  And, in most cases, they work almost perfectly on the first try.  The more common approach I've seen far too often is to rush into construction, then spend months putting on "Band-Aids" for all the things that were not well thought out up-front, and you end up with something more complex, and expensive, than it needed to be.  ANYTHING can be boiled down to very simple pieces if you think about it long enough.  Just yesterday I figured out how to eliminate one whole motor from the new ATC design, with no loss of functionality or performance.

A few of my favorite quotes:

"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." Antoine de Saint-Exupery (1900 - 1944)

Everything should be made as simple as possible, but not simpler !
--Albert Einstein

Any intelligent fool can make things bigger and more complex... It takes a touch of genius --- and a lot of courage to move in the opposite direction.
--Albert Einstein

Regards,
Ray L.
Regards,
Ray L.

Offline derek

*
  •  201 201
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #487 on: February 04, 2013, 10:14:35 AM »
If you decide to go with the BT30 be careful with your fork design. I made mine based off of Lyndex un balanced tools. When I purchased my tools from Mari they have balance holes in the fork groove. I had to rework the fork tips to slide over the balance drill points.

Derek

Offline BR549

*
  •  6,874 6,874
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #488 on: February 04, 2013, 10:32:28 AM »
Steve not all CNC bridgeports are rigid head. 

(;-)TP

Offline simpson36

*
  •  1,374 1,374
    • View Profile
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #489 on: February 04, 2013, 11:52:53 AM »
Steve not all CNC bridgeports are rigid head. 

(;-)TP

I'm aware. But it seems to me that the machines with fixed heads were designed from the git-go to be CNC and the others are in the same population as the masses of other 'converted' manual knee mills.

In my view, a typical manual knee mill is just fundamentally the wrong arrangement for CNC. The fact that you can buy lots of differnet ones in CNC trim doesn't mean it is a good idea. So the question remains, for those mils that HAVE  rotatable, nodable, or otherwise adjustable heads, how much are these features actually used on a CNC mill . . if at all.