Phase 2 Rotary Table

[Machinehead56]

https://youtu.be/0nMn9z9lwm8
Please review the video link and give me your thoughts on repairing this table to make it work. The worm gear shaft does not rotate independently inside the eccentric shaft. Is the .072" runout of the eccentric shaft the problem in your opinion?

 

[eKretz]

First check the ID/OD fits and make sure there's clearance. Next make sure you don't have any burrs around that little groove. Was it assembled when you got it?

The eccentric is there to disengage the worm for quick table movement or to adjust out backlash. For some tables for both.

 

[John Garner]

The worm shaft must rotate within its journal in the eccentric. The worm shaft journal is deliberately offset from the eccentric centerline, to enable the worm shaft journal -- and thus the worm shaft and the worm itself -- to be moved closer to, or farther from, the wormwheel.

If the worm shaft doesn't rotate within the eccentric when the eccentric is in your hands, find and fix that problem before worrying about putting the eccentric into the table base.

Once the worm shaft rotates freely and smoothly within the eccentric, you can think about installing the eccentric into the table base. When doing so, "clock" the eccentric so that the worm shaft is as far as it can be from the center of the wormwheel.

Only after the eccentric is fully seated in the base should you rotate the eccentric to engage the worm and wormwheel teeth. The goal is to have the worm barely clear the wormwheel at their closest engagement; the closest engagement will be influenced by the residual eccentricity of both the worm and wormwheel.

 

[Machinehead56]

"If the worm shaft doesn't rotate within the eccentric when the eccentric is in your hands, find and fix that problem before worrying about putting the eccentric into the table base."

John,
Thanks for your reply. I am going to drill and bore the eccentric sleeve oversized so i can plug it and redrill/ream the hole for the worm shaft. Right now, the two don't fit together at all. Too radical? What do you think?

 

[eKretz]

Did you read my post? What were the results of your examination? If you can not even inspect and report back I'll let John take it from here. And for the love of Mike, don't use a caliper.

 

[John Garner]

Yes, way too radical. The clearance between the eccentric and worm shaft should be very small, just enough for a film of light oil . . . probably right around 0.0005 inch on the diameter. That small a clearance will not fit together easily.

Any burrs or dings on these parts will keep them from fitting together. Examine the shaft and bore edges with a magnifier, and smooth out all burs, dings, and sharp edges with a "honing stone". I'd also stone a bit of chamfer all around the edges of the journal surfaces of both the worm shaft and eccentric to ease the assembly.

I can't tell what is stopping the worm shaft's sliding into the eccentric in your video; it could be as simple as not having the shaft journals lined up with the eccentric's bearing bore, or some obstruction down inside the eccentric, but your banging the worm shaft against the eccentric is almost certainly doing damage to whatever interfaces are colliding.

 

[Machinehead56]

Yes, way too radical. The clearance between the eccentric and worm shaft should be very small, just enough for a film of light oil . . . probably right around 0.0005 inch on the diameter. That small a clearance will not fit together easily.

Any burrs or dings on these parts will keep them from fitting together. Examine the shaft and bore edges with a magnifier, and smooth out all burs, dings, and sharp edges with a "honing stone". I'd also stone a bit of chamfer all around the edges of the journal surfaces of both the worm shaft and eccentric to ease the assembly.

I can't tell what is stopping the worm shaft's sliding into the eccentric in your video; it could be as simple as not having the shaft journals lined up with the eccentric's bearing bore, or some obstruction down inside the eccentric, but your banging the worm shaft against the eccentric is almost certainly doing damage to whatever interfaces are colliding.

John,
There's a .072" difference in hole location from end to end of the eccentric shaft. I'm not dealing with a burr issue or grit. The eccentric shaft bore is completely off location. I would post a picture of the gap but I don't see an option to do that. The worm gear shaft slides easily into the eccentric shaft until the second bearing surface of worm gear shaft reaches the entry point of the eccentric shaft.

 

[Gordon Heaton]

Were these parts ever together? If not, do they even belong together? Nothing is bent, just straight-line offset?

 

[e-fishin-c]

I commandeered a nice Phase 2 rotary several years ago. It was believed the internal gears were stripped, ended up being just out if adjustment. That cam is intentional and used to adjust the gear clearance.

 

[John Garner]

I've never seen a Phase II rotary table, let alone spent quality time with one. I made some comments based on my general knowledge of rotary tables, and other comments based on my general knowledge of assembling close clearance shafts and bearings.

I hesitate to comment further without a personal lookee-touchee-feelee session with the eccentric and shaft in question. The best I can offer is tu reiterate that the bearing areas should be very close clearance, that it only takes a little bit of trash or burr to keep the assembly from going together or rotating freely and smoothly, and the eccentricity is deliberate.

Ok, one last comment. Try to track down the factory instruction sheet for your Phase II rotary table. If you can't find a Phase II instruction sheet, look for an instruction sheet for a looks-just-alike table.

 

[eKretz]

I think plastikdreams should field this one.

 

[Machinehead56]

Were these parts ever together? If not, do they even belong together? Nothing is bent, just straight-line offset?

Yes, it came completely assembled but did not function. I disassembled this to find the manufacturer forced the worm gear shaft inside the eccentric shaft and called it good.

 

[Machinehead56]

I've never seen a Phase II rotary table, let alone spent quality time with one. I made some comments based on my general knowledge of rotary tables, and other comments based on my general knowledge of assembling close clearance shafts and bearings.

I hesitate to comment further without a personal lookee-touchee-feelee session with the eccentric and shaft in question. The best I can offer is tu reiterate that the bearing areas should be very close clearance, that it only takes a little bit of trash or burr to keep the assembly from going together or rotating freely and smoothly, and the eccentricity is deliberate.

Ok, one last comment. Try to track down the factory instruction sheet for your Phase II rotary table. If you can't find a Phase II instruction sheet, look for an instruction sheet for a looks-just-alike table.

Thanks for your input thus far John. If I put this all back together and fill it with oil, do you think it would then turn?

 

[CarbideBob]

The screws in the groove have been removed?
What happens if you put the shaft into the housing backwards? IE: gear out where the handle belongs.

 

[John Garner]

As I'm looking at the situation, I think the key to the problem is getting the wormshaft all the way into the eccentric, in such a way that the shaft turns freely, with miniscule clearance in its bearings.

Once that's achieved, I believe the worm-and-eccentric assembly can be slid into the table base casting. My guess is that the worm and wormwheel teeth will interfere with each other unless the eccentric is clocked within the table base so that the worm is as far away from the wormwheel as the eccentric will allow.

When the eccentric is seated within its bore, and clocked so that the worm clears the wormwheel, the table top can be rotated by hand, but not by the worn.

At that point, you'll want to rotate the eccentric to move the worm toward the wormwheel. The worm and wormwheel teeth can engage only when one gear's teeth can fit between the other gear's teeth. This means that you'll need to rotate either the worm or tabletop (and thus the wormwheel) while rotating the eccentric. Once the teeth start to engage. Continue rotating the eccentric until the teeth bottom, and then back off a touch.

At this point, you'll want to put the wormshaft graduated collar and crank handle back on. Then turn the crank until you either find a tightening of the gears (at which point, use the eccentric to gain a bit of clearance between the worm and wormwheel, OR the table top rotates a full turn without perceptible binding.

Worm and wormwheel lubrication? I've worked with rotary tables that are oil lubricated, and ones that are grease lubricated. I don't know if your Phase II table is supposed to be oiled or greased, but in either case, it's a good idea to lubricate the bearings and gears with an appropriate lubricant before assembly.

 

[Machinehead56]

The screws in the groove have been removed?
What happens if you put the shaft into the housing backwards? IE: gear out where the handle belongs.

Shaft (worm gear) will go in from both ends until the second bearing surface reaches the bore. Then it's a no-go.

 

[Machinehead56]

As I'm looking at the situation, I think the key to the problem is getting the wormshaft all the way into the eccentric, in such a way that the shaft turns freely, with miniscule clearance in its bearings.

Once that's achieved, I believe the worm-and-eccentric assembly can be slid into the table base casting. My guess is that the worm and wormwheel teeth will interfere with each other unless the eccentric is clocked within the table base so that the worm is as far away from the wormwheel as the eccentric will allow.

When the eccentric is seated within its bore, and clocked so that the worm clears the wormwheel, the table top can be rotated by hand, but not by the worn.

At that point, you'll want to rotate the eccentric to move the worm toward the wormwheel. The worm and wormwheel teeth can engage only when one gear's teeth can fit between the other gear's teeth. This means that you'll need to rotate either the worm or tabletop (and thus the wormwheel) while rotating the eccentric. Once the teeth start to engage. Continue rotating the eccentric until the teeth bottom, and then back off a touch.

At this point, you'll want to put the wormshaft graduated collar and crank handle back on. Then turn the crank until you either find a tightening of the gears (at which point, use the eccentric to gain a bit of clearance between the worm and wormwheel, OR the table top rotates a full turn without perceptible binding.

Worm and wormwheel lubrication? I've worked with rotary tables that are oil lubricated, and ones that are grease lubricated. I don't know if your Phase II table is supposed to be oiled or greased, but in either case, it's a good idea to lubricate the bearings and gears with an appropriate lubricant before assembly.

Thanks John. Getting the worm gear shaft in the bore of the eccentric is the crux of the problem. I'm going to bore out the eccentric shaft and press in a bronze bushing. Then, rebore the hole on location for the worm gear shaft.

 

[John Garner]

I think that would be a mistake.

Assuming that the worm shaft and eccentric you have 1) were, at some earlier time, parts of the same working rotary table, and 2) have not been significantly modified or damaged, they should 3) fit each other, and 4) be able to do what they are supposed to do when installed in the table.

I don't know what the table's designer intended is vis-a-vis the spatial interrelationship between the eccentric outer-diamer axis and the worm shaft axis, but I'm convinced that they were never intended to be coaxial. Instead, the intent was either 5) parallel but offset, or 6) at an angle to each other.

The hole you want to relocate didn't migrate from a formerly-correct location to a wrong location.

 

[CarbideBob]

Ignore or throwaway any eccentric thinking stuff. That just tosses you off course.
It is a shaft and a through bored hole with support on the ends as the shaft relived in the center.
Makes no diff if a square and triangle block or a an offset polygon or elliptical on the outside.
I suspect the worm shaft is bent or burred. Perhaps file a small chamfer on the lead of the second bearing start. Also on the oil groove. Mic the diameters.
The shaft should have center holes on both ends, do you have a bench center to check it on? Your lathe check seems to say true.
Since it goes in the same backwards the hole size seems okay.
Make a straight piece on the lathe or get some drill rod of the correct dia and see if it goes through.
I have never seen a bent body but I guess it is possible.
Bob

 

[eKretz]

I have never seen a bent body but I guess it is possible.
Bob

The worm shaft looks straight (enough). I am starting to guess he doesn't have the ability to actually measure the ID and OD close enough to actually check this fit, since he doesn't report back with sizes. But as you noted, if it goes in both ways, sizes should be okay. At this point I think I would recommend that he throw the eccentric back in the lathe and check TIR at both ends of the eccentric diameter as well as the middle and see if they match - that will tell if it's bent or warped. Could have taken a hard hit in shipping or just been poorly made.