A1-6 vs. D1-6 lathe spindles

I've owned a lathe with a D1-6 camlock spindle for many years and am very familiar with them. However, I have never used a lathe with an A1-series spindle and I found very little information on the net regarding them.

Does anyone have a link to A1-series chuck mounting instructions?

How long does it take to change an A1-6 chuck on a manual lathe? Compared to a D1-6 spindle does it take twice as long or more?

Are there any advantages of an A1-6 over the D1-6 chucks? Are they shorter or more rigid?

Thanks,

John

Pretty sure the main difference is the A6 uses bolts through chuck threaded into the spindle. D1-6 is cams as you know. Otherwise the spindles are very similar.
Might take a little longer to unscrew a bolt that to turn the cam but I dont see a big issue.
D1-6 is more common
I have an A6 chuck I need to add pins to so it will lock onto my D1-6 spindle. The centering taper is the same on both.
Link to detailed info:
http://www.usshoptools.com/new_web_2012/current_catalog_pdfs/mm_level_3_pdfs/101060_21.pdf

A type uses thru spindle tooling bolting exclusively. The idea being that it is for INFREQUENTLY changed spindle tooling - at LESS cost. No moving parts like D type

John, why do you emphasize INFREQUENTLY? Is it because of concerns about wearing out the threads in the spindle nose from years of use or just the inconvenience of changing relative to the camlock style? Also, how would you define "infrequently"? If you normally used a 3-jaw chuck and needed to use a 4-jaw once a week, month, quarter?

Thanks for your replies. I'm trying to get a better feel for the real world, operators perspective on the differences without actually laying hands on one.

I think this quote is the line I would choose - you pay your money and take your choice. Also - type of machine. Super versatile tool room lathe or turret lathe - where the extensive use of A type was the norm - after the demise of threaded spindle nose

just the inconvenience of changing relative to the camlock style?

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For anything over an 8" chuck, the logistics of moving the chucks and cleaning all the mating surfaces takes way longer than doing up the bolts on an A type, so the camlock really doesn't save any time, and the camlock will in fact take longer if you need to adjust any of the pins to get the cam to tighten correctly, which often happens when switching between 2 or more machines. I'd take either, wouldn't pay more for a camlock over an A type.

Less crap to go wrong with an A type than a D type. Also more compact and potentially shorter to design around - advantage A type.

Hey Guys,
Thank you for sharing your thoughts and experiences. I was thinking that it usually takes me 5 to 10 minutes to change a 10" D1-6 chuck. There's a minute loosening or tightening on each end of that time frame. All the rest of the time is spent cleaning, checking, and cleaning again, all of the mating surfaces and surrounding areas.

Take care.

D mount is more versatile for scroll and collet chucks...
My A1-6 mounted lathe is a great lathe, but I would trade the spindle out for a D mount spindle in a heartbeat because then it would be easier to find chucks and things I want.

For tooling that you want that doesn't have an integral A mount, screwing the backing plate onto the spindle and then screwing the chuck onto the backing plate seems ridiculous.
Also, the A2 bolt circle diameter is larger than the A1 bolt circle diameter, but most of the A mount scroll chucks you'll find use the A1 bolt circle for mounting...

Believe that for machines that get the work holding changed "often" the "D" setup is preferred and generally more common for engine lathes and tool room lathes.
Longer cycle machines where the chuck is changed less often seem to favor the "A" setup. Machines like turret lathes and turning centers.

When i bought my Romi M17 (flat bed CNC) i opted for a D spindle because all the other lathes in my shop had that style spindle and i wanted the option of flexibility between all my lathes.
Think the "A" spindles are prefered for larger spindles and higher speeds being regarded as more reliable for larger sizes.

Will say that the "D setup on med sized chucks (8-12") is easier to change than the "A: setup. The D ,having studs on the back of the chuck makes it easier to fit on the spindle. Chuck will stay on the spindle once the studs are started into their cam lock bores, there is no need to fumble with trying to clock the chuck to the spindle, while threading a bolt into the spindle, all while supporting a chuck ....


Cheers Ross

JohnnyJohnsoninWI said:

John, why do you emphasize INFREQUENTLY? Is it because of concerns about wearing out the threads in the spindle nose from years of use

Click to expand...

My view "infrequent" for the "A" mount depends on whether there is any useful life left in the workholder.

IOW - not meant to be swapped at all until due for rebuild, replacement, or sold out the door to make space for a new machine, outright.

D1 isn't because it is faster.

it is because D1 is "don't care WHATSOVER, nor in ANY way" what you might need to mount on the bizness side .

Any bolt / camlock / scroll-plate interference has already been taken care of, spindle side of the plate or "within" the body of the plate, and in ONE piece, no back-to-front bolting added, not two.