Frequently Asked Questions
These are the most common ways of dealing with rotary broach chips in blind holes:
1. Leave the chips in the hole.
Usually, the chips are compacted and have enough material to remain secured to the part.
2. Drill the chips out.
The same drill used for pre-drilling the pilot can be used too.
3. Remove the chips with an end mill.
This is popular because many fasteners do not have enough room for deep pilot holes and the end mill has a flat bottom.
4. Add an undercut.
The undercut provides a clean edge for the chips to break off and fall out of the hole.
5. Taper the hole.
A taper that widens from the front of the hole towards the bottom may allow the chips to break off smoothly and still provide enough engagement for the driver.
A note of caution:
Removing the broach before broaching is complete in order to remove chips is not always practical. It may seem tempting when dealing with chip issues, but the problem is aligning the broach with the hole to complete the operation. The spindle on the broach holder does not have an alignment feature, so it would have to be re-aligned manually or with some type of custom fixture.
Before choosing this path, consider a larger pilot hole or other means of reducing chip size.
*If you are not using the broach holder and are using the broach as a shaping tool by pressing, punching, peck mode or some other means, alignment may not be an issue.