FILENAMES: Bridgeport_Rotary_Table_Rebuild.txt Bridgeport_Rotary_Table.gif DESCRIPTION: This is an image of the parts diagram of a Bridgeport rotary table and a detailed description of rebuilding one. Posted by Mike Hanz . Mike provided the following description: ================================================================= This particular table was an eBay-acquired 15" model, in nice condition but needing a good cleaning and new paint job to match the looks of the restored mill. Standing it up on its back edge revealed a large nut with two holes meant for a pin wrench, along with a gush of fetid lubricating fluid from the bowels of the table. Okay, the instructions on the front said not to *invert* it, nothing about turning it on its back edge... :-) The solution to removing the nut looked simple...just make a wrench out of a spare 1/2" thick piece of 3" diameter CRS on hand. What could be easier? Decided to make a pin wrench that would both remove this nut and the lower quill nut on the Bridgeport - that needed a good cleaning and the collet locating pin in the spindle needed replacing anyway. Measured the pin distance. Hmmm, not the same, not even the same diameter! Oh well, close enough to allow one pair of pins on one side and another on the opposite face. Spent an hour happily making chips on the lathe and mill, finally plugged in the pins with some Loctite. Before removing the nut on the bottom of the rotary table, it's necessary to remove the closure plate on the bottom, retained by 4 flat head screws. Some care is necessary, as there is a large O-ring on the inner diameter of the closure plate that is easily nicked. Removal allows access to the side of the nut, where one finds an Allen head set screw bearing on a brass locking pin. Backing off on the set screw first prevents all sorts of dire consequences to the threads...I highly recommend it. :-) The nut retains a large thrust bearing that prevents the table from lifting upward under heavy milling. Removed the nut with a smug expression of satisfaction at the way the wrench worked. Peered inside the hole, and to my consternation see yet another nut buried 2" deep in a cylindrical cavity just slightly larger than the nut. At least the pins are the same dimensions and distance apart. Staring in dismay at the 1/2" thick pin wrench hot off the mill, I finally decide you can't get there from here and begin looking for the material needed to make a longer wrench. Two hours later, dirty and disheveled, I emerge from the basement darkness with the only stock that will remotely do the job - a 10" long piece of 6" diameter aluminum. No problem, I say to myself, it still fits in the 10" South Bend. Now, I'm here to tell you that it's amazing how much aluminum swarf you get when you turn a bar down from 6" to 3" in diameter. Momentarily considered renting a Bobcat with a bucket to clean out the garage, but cooler heads (my wife's) prevailed, and I spent the next hour sweeping up a barrel of chips. Drill and set the pins, then carefully remove the nut with the new tool, not quite so smugly this time. I had this horrible moment of panic as I unscrewed this second nut, suddenly visualizing yet a third nut underneath the second, maybe even a fourth under the third, and realizing that I sized the length of the tool just long enough to reach to the surface of the second nut and no more, but Murphy was kind to me. A few taps with a big brass drift and the table slid out of the base. One thing I hate about water based flood coolant systems is that they seem to get into everything, and the reservoir beneath the rotating table is no exception, despite the lack of an obvious entry route. I scooped out all sorts of really appetizing 'stuff' and rust, all possessing the tantalizing aroma of a long-dead swamp rat. Two weeks later, holding my breath all the while (okay, maybe I didn't work on it every minute), I finally had the base cleaned out and primed with new Rustoleum. I still get a whiff of the smell every time I walk by the trash can, though. I didn't bother to remove the worm shaft assembly, partially because it looked like it was in fine shape and partially because masking it off was a lot easier than pulling it out. Painting the base was easy, once all the chips and pits had been filled and sanded. Didn't try to make it into an show car finish, but it came out looking like new. The circular table disk came next. There are two oil channels drilled into the periphery, one of which feeds a radial groove ground into the bottom surface of the table. This bottom surface is finely machined and scraped, forming a large thrust bearing. On mine, the Gits oiler was missing the ball so I had to take it out with a drill, and blew out a huge amount of debris in the process of cleaning it. The other oiler feeds a long passage stuffed with a rope wick, gradually dripping oil on the top of the central roller bearing. It was clear, so I didn't bother to clean it. A Scotchbrite pad cleaned off the rust and other coatings off the bare cast iron surfaces that wouldn't get painted. WD-40 or CRC will keep those relatively bright, though I do wish I could find a cast iron polish that would work halfway well without darkening the surface. Re-assembly was relatively uneventful (unusual for me), but there were some interesting data points. The huge central bearing has a separate inner race that is an incredibly tight fit into the rollers. Since it fulfills an important role in achieving the accuracy specification, that makes sense, but it is definitely not a "lubricate and slide in by hand"operation. I took the table apart with it standing on-end (a couple of plywood boards prevented "oops" accidents if it had turned over.) Putting it back together, it seemed better to place the base horizontally and set the rotating table into the bearing, then tap it in with a brass drift. A slathering of synthetic way lube on everything seemed to help, and the table finally seated against the base. I had set the table up on a couple of 6"x6"x6" wooden blocks so I could reach underneath and avoid having to flip 220 pounds of cast iron around. There was enough room to put the bearing retaining nut on and cinch it up, then slip the bottom thrust bearing on. I used some EP grease on this bottom thrust face because there's no obvious route to receive much way lube from above. Seemed to work fine. With the worm shaft disengaged, I kept spinning the table and tightening the nut until I felt a slight drag, then locked the nut with the set screw. Back up at the worm shaft, I had broken it down to as far as the first thrust bearing in order to polish up the handwheel and fiduciaries, as well as clean everything. There is a cylindrical nut on this shaft that adjusts end play, buried under the cup that has the small oiler on top. Someone had let this adjustment get awry, and the two aluminum fiduciaries had started to grind away at each other in the clockwise direction. Not serious, but it made an awful noise in the midst of otherwise beautifully smooth, oily motion. It takes some effort to get this nut backed off to where it will turn, as it is retained by the usual set screw and brass locking pin, but it was possible to reduce the thrust bearing end play to essentially zero by tightening this up just finger tight. The only other adjustment of consequence is the degree of engagement of the worm gear with the ring gear on the table. That's done by loosening two button head cap screws on either side of the "on-off" lever escutcheon on the right rear and gently adjusting the gear mesh for full engagement. Getting over 200 pounds of rotary table up on the Bridgeport table was a two-man job, but it has turned out to be more or less a permanent fixture there. It's now a lot easier to return the vise to exactly zero or 90 degrees than with the swivel base that came with the milling vise. The surface is large enough to clamp most of my projects, so I won't have to pull it off very often. It also offers the opportunity to stick in a 7" riser I bought some time ago but didn't use because most milling would then need to be done with the quill extended too far. Besides, the table looks cool just sitting on the Bridgeport! :-) Mike Hanz Herndon, VA Parts list for Bridgeport Rotary Table.gif: Note: part numbers are for reference only. Always check with your Bridgeport dealer for latest part number. ITEM# CODE# PART# DESCRIPTION 1 2520011 RT-61 Assy., Hold Down and Hand 2 10l1051 .312-18 x x.625 Socket Head Cap Screw 3 2200098 M-47 Quill Lock Handle 4 1010514 RT-116 1/8 x 1/2 Roll Pin 5 2520065 RT-16 Clamp Bolt 6 2520064 RT-15 Table Clamp 7 2520089 RT-57 Oil Level Plug 8 2520062 RT-13 Engage Plate 9 2520061 RT-12 Engagement Stud 10 2520063 RT-14 Engage Knob 11 1011192 10-24 x .500 Button Head Cap Screw 12 2520059 RT-10 Back Pivot Bushing 13 2520060 RT-11 Back Pivot Bushing 14 2520058 RT-9 Cover Plate 15 1011216 10-32 x .187 Socket Set Screw 16 1011508 RT-115 6-32 x 1/2 Flat Head Screws 17 1011508 RT-115 6-32 x 1/2 Flat Head Screws 18 1011216 RT-109 10-32 x 3/16 Socket Cap Screws 19 2520092 RT-60 Set Screw Plug 20 2520058 RT-9 Cover Plate 21 1533102 RT-126 GB #520 Oiler Gits 22 2520551 RT-30 Index Plate No. 1 23 2520556 RT-35 Index Plate No. 6 24 2520560 RT-50 Index Plunger 25 2520559 RT-49 Index Plunger Sleeve 26 1011208 RT-122 6-32 x 1/8 Long Socket Screw Screws 27 2520562 RT-52 Index Plunger Handle Pin 28 2520552 RT-31 Index Plate No. 2 29 1010580 RT-153 3/32 x 7/8 Roll Pin 30 1522066 RT-124 .375 - .312 - 1.500 Compression Spring 31 2520564 RT-54 Sector Arm Screw 32 2520566 RT-56 Crank Adjacent Block 33 2520565 RT-55 Crank Block 34 1011005 Socket Head Cap Screw 6-32 x .750 35 1013077 Woodruff Key #5 36 1010725 RT-120 1/4 x 3/4 Dowel 37 2520563 RT-53 Crank Arm 38 1011234 RT-121 1/4 - 28 x 1/2 Socket Screws 39 2520557 RT-47 Sector Arm 40 2520558 RT-48 Sector Arm 41 1011533 RT-119 1/4 - 20 x 5/8 Flat Head Screws 42 2520078 RT-29 Worm Shaft Locknut Plug 43 1011216 RT-110 10-32 x 3/16 Socket Cap Screw 44 1520252 Thrust Bearings 45 1520253 Thrust Bearings 46 1523654 RT-113 Bushing 47 2520055 RT-6 Worm Shaft Bushing 48 2520057 RT-8 Pivot 49 2520056 RT-7 Index Holder 50 1533102 Oiler #530 Gits 51 1523654 Bushing 52 1520252 Thrust Bearing 53 1520253 Thrust Bearing 54 2520075 RT-26 Worm Shaft Locknut 55 2520097 RT-67 Vernier Dial 56 2520079 RT-37 Dial 57 1011533 Flat Head Machine Screw 25-20 x .625 58 2520080 RT-38 Handwheel 59 1011330 RT-137 1/4 - 20 x 3/8 Socket Head Set Screw 60 1013077 RT-133 #5 Woodruff Key 61 2520081 RT-39 Crank Washer 62 1191738 RT-112 5/8 - 18 Hex Jam Nut 63 2520087 RT-45 Handle Stud Pin 64 1522065 RT-118 Spring 65 2520074 RT-25 Handle Stud 66 1553103 RT-103 Gits #522 Oiler 67 2520082 RT-40 Handwheel Handle 68 2520054 RT-5 Worm Shaft 69 1520107 Race Thrust 70 1520106 Bearing 71 2520073 RT-24 Cover Plate 72 1520108 Nut Slot Insert 73 1011035 Socket Head Cap Screw .250-20 x 1.000 74 2520070 RT-21 T.A. Bearing Locknut 75 1520251 RT-104 Roller Bearing 76 12520112 Table Locknut 77 1520922 RT-108 Parker 0 Rings 78 1011517 RT-106 10-24 x 1/2 Flat Head Screws 79 2520102 Spacer Bearing 80 2520053 RT-4 Worm Gear 81 1010725 RT-120 1/4 x 3/4 Dowel 82 2530060 V-10 Vise Key 83 2520051 RT-2 12" Rotary Table Base 84 1010727 RT-101 1/4 x I" Long Dowel 85 1011056 RT-102 5/16-18 x 1-1/4 Socket Head Cap Screws 86 2520052 RT-3 12" Rotary Table 87 2520086 RT-44 Rotary Table Bushing 88 1195720 J-294 Wick .125 O.D. 99 2520084 RT-42 Dial Lock Screw 90 2520085 RT-43 Dial Lock Screw Washer 91 2520083 RT-41 Dial Lock Strap 92 2520078 RT-29 Worm Shaft Locknut Plug 93 1011022 RT-111 10-32 x I" Socket Cap Screws 94 2520068 RT-19 Zero Plate 95 2520069 RT-20 Zero Plate Washer 96 2520067 RT-18 Zero Plate Binder 97 1523820 Decal 98 1522870 Name Plate 99 1011552 RT-128 Drive Screw ATO x .25 100 2520077 RT-28 Worm Shaft Washer 101 2520075 RT-26 Worm Shaft Locknut 102 2520090 RT-58 Shaft Align Washer Pin 103 2520091 RT-59 Worm Shaft Bushing Upper