I've seen this mod done by several people out there. It seems that many people use these 5C Spin Indexers for MILLING, rather than for their intended purpose of GRINDING. Although it is a cheap tool that some people choose to use for milling indexed parts, it is really not meant to be used this way.Originally Posted by rolland
The spindle collar with the set screw that you have eliminated and replaced with threaded locking collars was meant to allow for setting spindle travel while grinding cylindrical parts on a surface grinder. Hence the name, "SPIN INDEXER." It is not for "removing endplay from the spindle."
For example, if you hold a 5/16" shaft in a 5C collet in the spin indexer and want to grind the end of the shaft down to 1/4", you would SPIN the spindle while lowering the surface grinding head a fraction at a time until the 1/4" diameter is achieved. However, you are limited to grinding an area only as wide as the grinding wheel if you lock your spindle with threaded collars. The Spin Indexer normally allows you to loosen the set screw in the spindle collar and slide the collar back as far as you need to allow adjustable movement of the spindle. This way, if you want to grind the end of the shaft down to a 1/4" for a distance of say 1.5" along the shaft, you can set the collar 1-1/2" back on the spindle and lock it with the set screw. Then, you can spin the spindle while sliding the shaft forward as you grind to cover a greater area of the shaft. The collar with set screw tightened will act as a STOP for the 1.5" travel of the spindle so that you will grind your shaft to the exact length desired.
Again, I can understand if you bought one of these tools as a cheap method of being able to mill indexed parts on occasion, but it truly was NOT designed for this purpose, which is also why they do not have T-SLOT holding provisions for milling tables. The 5c Spin Indexers are not very rigid and therefore have limited capabilities when it comes to precision milling. These 5C Spin Indexers were meant to be simply be held in place on a surface grinder's magnetic chuck, so bolt-down provisions are not required features of these tools.
If you own one of these 5C Spin Indexers and plan on modifying it with the threaded lock rings, you might want to re-consider unless you have two of them. One for grinding and one set up for milling. Otherwise, you're just ruining your 5C Grinding Spin Indexer.
If you are planning on modifying one of these tools for milling, adding slots for bolts to hold it down on a milling table is a good idea, but I would also recommend bolting KEYS on the bottom of the indexer to fit your table T-SLOTS in order to align it properly in the X-direction, parallel to your milling head.