What size rotary axis

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What size rotary axis

Postby martin54 » Sat Dec 09, 2017 12:36 am

Just wondering what sort of size rotary axis most people have, my machine would need major surgery to be able to use a rotary axis & while it is not beyond me to modify it myself I am unlikely to get round to it anytime soon due to health problems.
So another option might be to buy one of these cheap Chinese machines to get myself started, not really got a lot of money so it may also be a used one. Just trying to get an idea if something like that would be big enough, don't see myself making any long parts like stair spindles so will probably just be small bowls & things like that. :lol: :lol:
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Re: What size rotary axis

Postby Leo » Sat Dec 09, 2017 1:38 am

When I bought my Chinese machine I got it outfitted with a rotary axis. I don't swap axis wires to share a "Y" or '"X" axis or anything like that. I had an additional driver installed as an "A" axis. So, I have all 4 axis motions. I had choices with size of rotary and for such a low difference in price I went with the 200 mm (8") axis with a 30 inch bed. It's a little heavy but I can put it on the machine. It has NEMA-34 Stepper motor. If I had to do it again, I would.

On my laser machine I have a smaller rotary that does axis swap. That one is about 4". I have not tried it yet.

For me - this is it. I'm never going to buy another machine.
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Re: What size rotary axis

Postby garylmast » Sat Dec 09, 2017 2:20 pm

It really depends on how much Z height you have and if you can slide your spindle further up in it's holder or not. Remember the bottom of the mill needs to sit on top of material when it's sitting in the indexer, plus be able to raise for whatever clearance you programmed. On an older machine, where the clearance between the spoil board and the rail was about 11", I was able to turn a little under 6" diameter, with the spindle raised at maximum height. On my newest machine, I'm able to turn 20" in diameter. Another pain in the butt, that I will never go through again, was with a machine I couldn't get rid of fast enough. I had to switch the A drive with the X drive and then go through re-calibrating every time. Having a separate A-drive is more desirable. Don't be afraid of the Chinese indexer, they are well built and low priced.

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Re: What size rotary axis

Postby Leo » Sat Dec 09, 2017 3:10 pm

Just a note. I am sure I will get beat up over this, but.

An indexer is a rotational axis that rotates from one given degree to another given degree. Most are 1 degree increments, some are 5 degree. So you index to a specified rotation and do machining at that rotation angle, then move to the next rotation. It is not necessarily programmable accept for rotation to the specified angle and a feedrate is not commanded. Machining is not done during rotation.

A Rotary axis is one that is programmable and rotates with a feedrate commanded as machining is being done. This is the popular item in the hobby world.

It is a mistake that even seasoned machinists make. I buy this stuff professionally in industry so I need to be sure of what I am purchasing. If you go to a manufacturer of these devises like Haas and ask for an indexer, they will ask "what increment do you want". If you ask for a rotary axis, they will sell you a rotary axis. Normally, a rotary axis will cost substantially more.

Most people in a hobby environment do not know this and call it an indexer, but in fact it is a rotary axis. There IS a difference.

It's just a pet peeve of mind, sorry. :wink:
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Re: What size rotary axis

Postby garylmast » Sat Dec 09, 2017 3:31 pm

It is a mistake that even seasoned machinists make.

Good thing I'm not seasoned, just old and my memory only lasts for a few seconds. You beat me up once before for calling it an indexer. A few more times and I will start calling it by the correct name. Now what was it called again...an indexer or rotary axis? :D :D :D :?: One of these days, I'll show you a picture of my Monkey Wrench.
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Re: What size rotary axis

Postby Leo » Sat Dec 09, 2017 3:52 pm

garylmast wrote:
One of these days, I'll show you a picture of my Monkey Wrench.


I'll just follow up with a Stilson, or a Cresent. Maybe I'll post an Allen Wrench. BTW - I do know what a monkey wrench is. I have one - in the tool box draw with the stilsons

Not meaning to beat anybody up. I am not a diplomatic person, but I do wish to educate.
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Re: What size rotary axis

Postby IslaWW » Sat Dec 09, 2017 4:29 pm

Martin...
This snip from my rotary class may help you decide what size you can use. Remember you will need equal room UNDER the rotary centerline
Attachments
Rotary Clearance.PNG
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Re: What size rotary axis

Postby martin54 » Sat Dec 09, 2017 9:41 pm

Thanks for taking the time to reply, I am not really to bothered about swapping the axis over, since I am only thinking about doing this so I can try some rotary work then it will get set up that way & stay like it :lol: :lol:

I am not replacing the machine I already have, ideally I would convert the machine I already have, raise the gantry, extend the bed & fit a rotary axis but I know that is not something that will get done for a long time if at all :oops: :oops:

Will have a look at that thanks Gary :lol: :lol:
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Re: What size rotary axis

Postby Greolt » Mon Dec 11, 2017 11:29 pm

martin54 wrote: I am not really to bothered about swapping the axis over, since I am only thinking about doing this so I can try some rotary work.................



One small consideration is to select a rotary axis stepper that will happily run at the same amperage as the Y axis stepper it will replace.


As an aside, I sometimes use a rotary axis as an indexer. But it is SO MUCH MORE than an indexer.


Another idea if you happen to be a wood turner, is to have the same chuck mounting method on the rotary as is used on your lathe.

It can be very handy to turn a shape on the lathe. Transfer job still mounted in the chuck to the rotary axis. Do some CNC carving. Return the chuck with job to the lathe for finishing. All with one setup.
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Re: What size rotary axis

Postby TReischl » Thu Apr 05, 2018 8:14 pm

Greolt posted a gem above about setting up the rotary so it can use the same chuck as on your lathe. That is hugely important, unless you like sitting around watching a rotary axis slowwwwllllllyyyyyyy remove the corners on square blank or you do not plan on ever hollowing out anything from your rotary axis.

I took it a step further. I do some hand carving...OMG!!! Don't shoot me! So I bought a carving vise (LeeValley) that has an arbor that fits the thread on my chucks. So I can go back and forth between lathe, rotary axis and hand carving without ever unchucking the work. Life is good!
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