6inch Rotary Table Conversion Guide
The major work in converting a rotary table is not in the addition of the stepper motor drive, but rather in the cleaning and lubricating of the table prior to modifying the table at all. This guide is based on one of the 6" Chinese rotary tables, which I forget where I obtained it now, but the procedure should be similar for other tables Additional notes and pictures from other users would be welcome.
TODO - ( Forgot to take a picture before I stripped it )
Stripping the table down is relatively easy, and involves removing the various elements in stages. The exact details may vary from table to table, but the general arrangement is similar across all the cheaper chinese copies. the handwheel is removed from the end of the shaft, followed by the collar and quick release/backlash adjuster plate. It is this plate that will take the motor mount when re-assembling the table, but for now it is just a matter of putting it to one side so that the shaft retaining plate can be removed. The plate is held on with four allen bolts, and has four further allen set screws to adjust the distance from the plate to the collar on the shaft. It may be worth marking the plate before removing it, and leaving the set screws untouched, but since we are fully stripping the unit, some adjustment may be required later anyway. In addition to the plate, there is an adjustment set screw in the side of the casting and the retaining thumb screw in the top,. These need to be fully removed before the shaft is extracted. Once all of these clamps are removed, it should be a simple matter of rotating the table while pulling the shaft out of the casting, but I found that it was easier to remove the table before extracting the worm gear, as twisting the shaft to remove it is easier once the worm gear has no obstructions. The table is retained with a lock plate on the bottom of the it's shaft, and has an allen set screw to secure it. Loosen the set screw, and then the ring can be rotated off the end of the shaft. There are two spigot holes to assist this, but I found that the hex key provided enough leverage to remove the ring. Once off the table should be turned over, and the thrust bearing removed for safe keeping. At this point, the main body of the casting can be lifted off the table. And then the drive shaft is free to rotate and be removed from the casing.
This gives the set of components displayed above. ( Click on the pictures for an expanded view ).
Once extracted, the reason of wanting to clean and lubricate the table will be obvious.
I'm glad that the table has had little use manually, as the level of swarf contained in the grease was somewhat disturbing. Removing it and replacing it with clean grease and old needed to be carried out even if I was not going to convert the table to motor drive.
One problem I has still to solve is how to extract the key from the shaft so that I can dismatle and lubricate that. The key has been pressed into the shaft and may need to be filled away so that the oldham coupler can later be fitted to the shaft.
OK this is how the woodruff key looked after extracting it ...
Having used the brut force and ignorance method of removal, with a little help from the next door neighbour - who has a bigger hammer ...
This allowed me to check out the assembly of the drive shaft with adapter.
Don't worry about the diecast box lid on the stepper motor. I'm working on a few things at the same time. All will become obvious later. In the meantime, I will dismantle the assembly and produce some pictures of how it all goes together. As the drive shaft is simply dry fitted to the excentric mount, it is not the smothest of actions. At some point I may fit roller needle bearings - when time permits. At present it moves reasonably freely, and without any noticable movement off axis.
I need to finish cleaning the base and table before I go any further.
Next step is to clean away all the rubbish prior to tidying the matting surfaces and re-assembling the table.
Parts will be visiting an ultrasonic cleaning bath this week - which is currently out of action.
Watch this space for the next stages of assembly. The gallery of images for this can be found here.