PTG 125 Speed Indexer FAQ s



  1. Why an indexer and not a True 4th axis?

The most obvious is the price. The unit is a very cost effective way of increasing production on your vertical machining center without breaking the bank. Interfacing is very easy and quick and more than one machine can be interfaced to use the indexer without the need for a very expensive 4th axis drives. This gives flexibility within the workshop. The Indexer is very quick in operation and allows machining operations on more than one face ensuring that productivity is increased.


  1. What are the standard indexes?

15, 30, 45, 60 & 90 degrees adjusted by a stop screw. This range is the most popular used throughout the engineering industry. Stop screw adjustment is made in minutes and changes the index immediately.


  1. Can I easily interface it to my CNC machine?

Yes, one spare M Code (mfin) is all that is required to operate the unit from the control. A competent electrician can wire the unit very easily.


  1. How accurate is the unit?

The unit is very accurate and indexes to within one minute of arc. There is a double taper system that locks the unit and the unit will maintain accuracy throughout its working life in normal usage. The main spindle has a runout tolerance of .008 mm.


  1. How fast is the Index?

Dependent on the load, a normal 90-degree index is less than one second!


  1. How robust is the unit?

The unit is very robust and is an all Cast Iron body with a minimum wall thickness of 22mm. The unit weighs 28 kegs and can withstand milling and drilling operations.


  1. What about maintenance and spare parts?

The unit requires minimal maintenance, just regular oiling, and wear parts are virtually nonexistent.


  1. Can you supply “Turn –key“ packages?

Yes, with our long association with PTG we can call on many years of experience in manufacturing and using indexers. Our designers have designed and supplied a vast range of units fitted with bespoke fixturing, workholding systems, baseplates, multiple unit set-up’s and we constantly supply machine tool dealers and manufacturers with turn key packages ready to fit to machines.


  1. If I have a Special Indexing requirement what can I do?

We can manufacture special kits to fit the unit, which can be fitted in around 30 minutes by the end user. The standard kit can then be refitted when required. Please contact us for a quotation.


  1. Can I put more than one unit onto my machine?

Yes, Multiple set-ups are a common practice and up to 4 units can be linked which operate from one “M“ Code on the machine.


  1. What loads can be held in the PTG 125 Speed Indexer?

When the unit is used in normal operation, i.e. spindle horizontal, then 25 KGS can be held in the unit. All loads should be as central and balanced as possible. In the spindle vertical mode then 50 KGS can be rotated.


  1. Which way does the unit rotate, and can it reverse?

No. The unit operates anticlockwise as you look at the spindle nose, it cannot reverse.


  1. What work holding systems can be used?

The unit has a 40 mm h7 spindle nose register and a jig bored 6mm location hole at the 12 o’clock position to locate any required work holding. Commonly used are 3 jaw chucks collet chucks, fixture plates, and expanding mandrels. Pneumatic and manual tailstocks are available from stock.


  1. What are the power requirements?

Standard shop air supply of 60–80 Psi, 24 Volt supply from the machine control.


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