Toolholders (Haas UMC-500)
We have standardised on ER16 and ER25 collet chuck tool holders, with a gauge length (the distance from the spindle face to the face of the collet nut) of 100 mm. The spindle taper is BT40. There are some additional "special use" tool holders which are different, but the majority are the collet type.
Additional toolholders can be ordered from Cutwel:
ER Collets
Collets should only ever be used to grip something smaller than the marked size. A standard precision collet has a clamping range of 1 mm so therefore a 12 mm collet can clamp between 11 mm a 12 mm, no more and no less. Clamping outside of the normal ranges will lead to damage to the collet, the tool holder, or the tool. Poorly clamped tools may come loose at inopportune moments and damage the work, the tool itself, and the tool holder.
Where possible stick to the nominal size collet for your cutting tool wherever possible. If you have a 6 mm shank endmill, it should go in a 5 mm - 6 mm collet, not a 6 mm - 7 mm collet. The more the collet has to clamp down and deform to grip the tool the less secure it will be.
We keep a stock of typical standard collet sizes in the brown drawers, and a full range in the tool cabinet drawers to cover odd circumstances. Please ensure you clean the collet and the taper they seat against when changing a tool.
For more information about using ER collets, check out this video from Haas Automation.
Hydraulic Toolholders
There are a few short gauge length hydraulic holders for fine finishing tools. These work by compressing a hydraulic fluid in a cavity which causes a thin wall section of the tool holder to expand and grip the tool. This hydraulic gripping has a slight dampening effect on the cut and by virtue of the precision fit of the cutting tool to the bore the run-out is quite low straight out of the box.
The downside of hydraulic holders is cost - each one costs more than £150 versus about £35 or so for an ER collet toolholder.
Pull Studs
All of the toolholders installed in the machine use through-coolant pull studs. This is to prevent catastrophic damage to the spindle which would occur if the through-spindle coolant was enabled with a solid pull stud installed. In this case the pressurised coolant would flood out of the rotary union joint and flow into the spindle bearings, requiring an expensive complete spindle rebuild.
Pull studs should be fitted firmly to the thread in the back of the toolholder using a small amount of "Blue Goop" anti-seize thread lubricant to prevent the threads from sticking together permanently. Spare pull studs are kept in the brown cabinets behind the lathe and can be ordered in bulk from Cutwel if required.
When you order new pull studs make sure they are exactly the same - if the size or shape is different then there is a significant risk of the tool holder falling out of the spindle during tool changes or at high RPM. If you're unsure check the graphic on the front of the machine.