View Full Version : tapping chrome plated shaft?

01-29-2005, 11:47 AM
Is it wise to cut or drill and tap threads into a 1/2" Hardened precision chrome plated steel shaft. The one I purchased is flexing too much. Or maybe somebody has a genius idea as to how to support it without tapping holes? Will the chrome plating chip off and ruin the surface?

01-29-2005, 12:10 PM
I would imagine that some of the chrome would chip off. But it should be pretty localized to the area of the hole.

ahmed drdeer
01-29-2005, 12:14 PM
Yes you can ..first you have to remove the hardend alayer whith a carbid end mill this alayer is about(.05to3mm) over the diameter acording to the type of the chrome plated steel shaft.it mean's that the shaft will have a small flated aria which will allow you to start drilling
then you can drill the hole with HSS dril after that you can tape the hole .
best wishes

01-29-2005, 12:17 PM
I wouldn't anticipate any problems with it. You might consider hitting the spot you want to drill/tap with a flapwheel to remove the chrome from the area. That could help prevent any chipping from the drill bit or tap. The flap wheel shouldn't chip anything, just polish the chrome off of the spot. The hardened part will probably be the biggest challenge, you'll want a good bit and good tap and lots of cutting fluid!

01-29-2005, 12:42 PM
Or maybe somebody has a genius idea as to how to support it without tapping holes?

I would also be interested in a solution to the support-problem...without spending hundreds of dollars :p

01-29-2005, 12:53 PM
If it is truly a piece of induction hardened shafting, you will have a very hard time doing anything with a thread tap in this material, short of annealing the spot where you intend to make the hole.

If you can center punch it, and make a dent, then you won't have any trouble. Wear safety glasses, and keep onlookers away, because it will break the end off your center punch if it is a hardened shaft.

01-29-2005, 01:10 PM
I would imagine it is a piece of "Thomson" type linear bearing shafting.
As most of the previous posts remove 0.050 from the outer surface (however you like (Dremel, hand grinder, CBide cutter)) and then it will machine/drill with standard HSS.
If it is through hard (as Huflung mentioned) you will need to EDM tap the holes.

01-29-2005, 03:19 PM
One of the "tips 'n tricks" from the clockmakers of the world, when they have to drill holes in the end of delicate but hardened spring steel, is to anneal just the spot where you're going to drill the hole.

To do this, chuck up a dowel, metal rod, or similar into your drill press. The friction will cause very localized heating, and make it possible to drill in exactly that spot, without much damage to the surrounding areas.

Thought it was a good tip...I've never tried it, myself.

-- Chuck Knight

01-29-2005, 06:23 PM
Hey, Chuck, that might be a good tip worth remembering. It should help on "cheap" non-alloy carbon steels that are prone to losing their temper very easily when heated. I'd still preheat the area to 400°F first, so help remove the quench effect.

I know I've done the opposite quite successfully: run a dulled HSS drill on stainless such that the drill spot hardens the work. Its kind of alarming to see this red hot glowing tip where the drill used to be :(