Lucas Rotary Tables have been manufactured for many years and the designs of the earlier tables is quite different from the design of the newer tables. The newest design of standard rotary table used a pair of Timken bearings mounted on a central stud (or post), a ring-shaped circular way and uses the Lucas-proprietary 'air lift' system to reduce friction. The tips in this document are known to apply only to this design of rotary table; however, the tips may be useful on earlier designs as well. You will need to make the final determination.
- To remove a female tapered lockbolt bushing from the 'blind' hole in the side of the rotary table top, pound a close fitting pin into the straight central hole in the bushing after packing the entire bushing center and the cavity behind it with a stiff grease. The hydraulic pressure thus generated will 'jack' the bushing out of the hole. I prefer a somewhat smaller pin fitted with a small square of cloth on the end that will function like 'shotgun wadding' to help seal the pressure. With a properly sized pin, the pin will cut the 'wadding' as the pin is driven into the hole.
- The Clamp Shaft of split ring type clamps has a cam machined into the side of the shaft, whose purpose is to operate an air valve inside the table. If the timing of the shaft is not proper, the airlift system will not properly energize when the clamp is released. The Clamp Shaft has a small bolt projecting from the side to prevent the shaft from being completely 'unscrewed' from the clamping nut. The head of the bolt strikes the top surface of the table base at approximately the '8-OClock' position when looking at the end of the shaft. The shaft should be 'timed' by 'jumping' the position of the flats on the side of the Clamp NUT until the clamps are tight when the bolt head in the side of the Clamp Shaft is at approximately the '2-OClock' position.
- The amount of air pressure used to apply airlift to a rotary table is an operator adjustment. It should be adjusted for greatest ease of table rotation. Too little airlift can cause the table to be hard to rotate. Too MUCH airlift will also cause the table to be hard to rotate by lifting the table so high that it drags on the 'bottom' of the released clamps. While the table is rated for a maximum airlift of 80 PSI, I normally expect an empty table to rotate easily with 5 to 10 PSI of air pressure. 80 PSI is only necessary if the table is loaded to near maximum weight capacity.
- On the top of the rotary table directly above the center stud is a removable cap to gain access to the center bearings. This cap is held down with 2 heavy bolts whose heads span across the main tabletop and the top of the cap. The bolt heads are recessed into the tabletop and are usually removed with a pin-type spanner wrench. Be ABSOLUTELY CERTAIN that these bolts are present. If the bolts have been removed, the bearing cap can be 'blown off' by air pressure when the airlift system is pressurized. I have heard reports of the bearing cap being blown completely through the roof of buildings!
- Lucas rotary tables MUST be installed and tested only when mounted to a properly flat surface. If you place a 0.005 thick shim between the bottom of a Lucas rotary table and the top of the machine tool table on which it is mounted, I do not expect you to be able to rotate the table. If you CAN rotate the table it is in need of rebuilding.
- An airlift-type rotary table should NOT be able to rotate without air pressure applied to the airlift system.
- The air lines servicing a Lucas airlift rotary table should be a minimum of ¾ trade size and should NOT be equipped with 'quick disconnect' fittings. The 'shutoff poppet' inside the 'quick disconnect' fitting will cause a pressure drop across the fitting and will severely restrict the flow of air. The airlift system will not function properly. I suggest the use of simple union fittings and a ¼-tyrn ball valve for shutoff.
- Tables that are equipped with solenoid valves for control of airlift, clamps or lockbolt require an airline lubricator filled with Mobil DTE-24 to keep the spools of the air valves lubricated. This lubricator should be 'upstream' of the valves it is lubricating. ALL airlift rotary tables need an airline lubricator to feed oil to the ways. This lubricator should be placed 'downstream' of any valves that the table may be equipped with and directly before the table airlift 'in' port. This lubricator should be filled with Mobil Vactra-4 oil. The oil regulation screw should be set to maximum 'drips per minute'. Since the oil is extremely thick and oil will only be used when the airlift is on - typically only long enough to rotate the table from one position to another - a less than maximum setting will likely result in the table ways receiving no lubricating oil at all.
- Lucas literature already states that the Lockbolt should not be used to stop the rotation of the table. That having been said, I believe that more explanation is needed. Certain other brands of competitive rotary tables are designed to have the lockbolt used to stop the table rotation. The Lucas table was not designed to be used this way and WILL be come damaged - probably the very first time you do it. A visual examination of the Lucas Lockbolt will show that only a very small 'tip' area of the lockbolt engages into the female tapered lockbolt bushings. The lockbolt tip is only about the size of the tip of your little finger. It is a precision positioning device. It is not a 'stop'. Stopping the rotation of a Lucas rotary table by using the lockbolt is akin to using a micrometer for a 'C' clamp. Don't do it!
- Lucas literature does NOT state, however, I recommend that after the rotary table is positioned to location and clamped, that the lockbolt be withdrawn from the table. Here is how I look at it. In the event of a crash of sufficient force to cause the rotary table clamps to slip, it is not possible that the extremely small tip of the lockbolt is going to prevent the table from moving and save the work from being damaged. What will actually occur is that you now have not only damaged work; you also have a damaged rotary table.
- When clamping a part to the Lucas rotary table, be aware that it is possible to warp the entire rotary tabletop into an out-of-flat condition by improper clamping.
- While Lucas rotary tables are rated to carry a tremendous amount of weight, the ratings are based upon a central load. Load capacities are based on the Nominal diameter of the ring-shaped way area between the top and bottom of the table. The actual load capacities of the tables are:
25-Inch Baseplate 8,000 Lbs
36-Inch Baseplate 16,000 Lbs
48-Inch Baseplate 27,000 Lbs
60-Inch Baseplate 38,000 Lbs
While tests were done in the early 1960's to attempt to establish 'off-center' load capacities, no conclusions were reached and the data is inconclusive. The best that can be said is that the load rating is lower with 'off-center' loads. Many customers mount two identical parts to the rotary table to effectively 'counterbalance' the load and restore proper rotation.
