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oxford
10-05-2013, 10:42 PM
What are the advantages of a rotary table with x,y travel on it? Were they marketed for use on a machine that didn't have its own table travel, or am I missing something when using these on a milling machine table that already has x,y travel?

Mcruff
10-05-2013, 11:09 PM
A rotary cross slide has a ton of advantages over a rotary table.
the main thing is you can cut an oval all in one set up.
Locate the part cut a half circle , crank off the other end and then connect the sides to the 2 half circles.
now imagine what you do to vary this, different radius on each end, angled sides, curve in the middle all with changing the part location on the table, just move the cross slide over the swing point of the rotary table.

Doozer
10-05-2013, 11:19 PM
Yes, and the main takeaway here is the X-Y slides
need to be ON TOP of the rotary axis. Think Advance
and Yuasa and Moore and Hauser.
Palmgern made some weird azz table with the X-Y
slides underneath the rotary stage. I can't figure
out how that is useful.

--Doozer

Toolguy
10-05-2013, 11:36 PM
The Palmgren ones are useless with the rotab on top. The other ones essentially turn a Bridgeport into a die mill. A K&T rotary head mill is better, but harder to get or make room for in a home shop.

oxford
10-06-2013, 12:03 AM
Thanks, I understand now. I was thinking xy under the rotary not over it.

LES A W HARRIS
10-06-2013, 12:29 AM
oxford,
here is some old parts machined on a Yuasa x-y Rotary.

http://i37.photobucket.com/albums/e97/CURVIC9/NILLWORK/LAWH0209.jpg (http://s37.photobucket.com/user/CURVIC9/media/NILLWORK/LAWH0209.jpg.html)
and:

http://i37.photobucket.com/albums/e97/CURVIC9/NILLWORK/PANA0435.jpg (http://s37.photobucket.com/user/CURVIC9/media/NILLWORK/PANA0435.jpg.html)

and:

http://i37.photobucket.com/albums/e97/CURVIC9/NILLWORK/PANA0433.jpg (http://s37.photobucket.com/user/CURVIC9/media/NILLWORK/PANA0433.jpg.html)



Cheers,

Sun God
10-06-2013, 01:22 AM
Amazing parts Les!

I have always wondered why things like Volstro heads aren't more popular. I guess the loss of rigidity in general milling operations isn't worth the added flexibility of integral radius milling.

Arthur.Marks
10-06-2013, 09:49 AM
FWIW, the Palmgren type (XY under the rotary movement) is a great fit on a Rusnok milling machine. That is an odd case, though, as the standard XY table is only mounted to the base by four screws and designed to be removed for exchanging with other fixtures. If you need a large diameter rotary surface on a Rusnok, that is about the only way to fit it---and it fits very well in fact. Otherwise, I tend to think the intended use is for drill presses or the like: machines with a t-slot table and no other built in, controlled movement.

Toolguy
10-06-2013, 11:05 AM
The Volstro heads are a very worthwhile accessory. I have logged quite a few hours on them before CNC was in common use. They are light duty but high quality. They are very capable if you get them properly adjusted and don't try to push them hard. They will hold up to 1/2" end mill, but work best with 3/8 or under. I have seen some fairly cheap on eBay now that a lot of people have commercial and home CNC mills.
Some of the older technology is still very useful. Two items that come to mind are tapping heads on the mill or drill press and Volstro heads on a Bridgeport or clone.

Dr Stan
10-06-2013, 12:18 PM
In all of my time as a machinist & die maker I used a RT with a built in X Y table once. As others have said they have been rendered obsolete by CNCs and can now be bought for pennies on the dollar.

As with any other device/set-up one trades off rigidity for flexibility/movement. For the average or even the above average HSMer I would be hard pressed to recommend the purchase of one of these tools. Instead I'd find another way around the operation such as building a fixture to go on the RT or redesigning the part even if it required making two or more pieces instead of one.

Just my $0.02

duckman
10-06-2013, 01:13 PM
I was given a Yuasa rotary with X and Y on top 7" travel on both axis's, it's amazing what you can do with it, one project was to fish mouth some 1 1/2" SS pipe to be welded into a tee shape with no filler and had to hold 5,000 PSI we had to make 15 of these assembly's , also had to hold the length of the fish mouth piece, I didn't have any part of welding just made the parts, the welder came up and said thanks it was first time that he had put parts together that fit the first time with out any fitting required. As an aside I was told the co. that had bought the Yuasa paid in excess of $5,000.00 for it, they were going to throw it away and a friend that works there grabbed it for me, also got a 3' X 4' 8 thick lab grade granite table and stand for just picking up $0.00 same people.

bborr01
10-06-2013, 01:19 PM
I was given a Yuasa rotary with X and Y on top 7" travel on both axis's, it's amazing what you can do with it, one project was to fish mouth some 1 1/2" SS pipe to be welded into a tee shape with no filler and had to hold 5,000 PSI we had to make 15 of these assembly's , also had to hold the length of the fish mouth piece, I didn't have any part of welding just made the parts, the welder came up and said thanks it was first time that he had put parts together that fit the first time with out any fitting required. As an aside I was told the co. that had bought the Yuasa paid in excess of $5,000.00 for it, they were going to throw it away and a friend that works there grabbed it for me, also got a 3' X 4' 8 thick lab grade granite table and stand for just picking up $0.00 same people.

Stop it Duckman, you're going to make Flylo cry. LOL.

Brian

Forestgnome
10-06-2013, 02:38 PM
Basically they allow you to change the center of rotation without refixturing the part. Very useful when you have multiple curved features that need to be milled. Very tedious otherwise.