What is the best tool to drill 1/4" holes through 1" solid 304 stainless rod on a mill/drill?

[rons]

If you don't go for a carbide solution then use a 3/16" diameter cobalt drill bit.
Follow with a 1/4" HSS 4 flute cutter with some WD-40.
The holes will look much nicer than if you used a 1/4" drill bit.

 

[L Vanice]

Yeah, I have to flatten 1/6" on two opposite sides of the rod anyhow, so that would work perfectly.

So just center punch a hole and this carbide tipped die drill bit should be enough?

If your center punch does not get a flattened end after trying to ding the rod, then the rod is soft and you do not need a die drill to do the hole. But a good cobalt drill bit with a split point will be worthwhile because it should last longer than a cheap bit.

Larry

 

[dgfoster]

You say in your profile you are the owner of a small tool company. I have no idea what machine tools you have available. But making (or buying) a guide for a hardened 1/4" drill bushing may help you easily find center and reduce drill bit (or end mill) wander as you bore the hole. There are many styles available. A custom one consisting of a block of steel bored with a horizontal 1" hole and then accurately vertically drilled for the bushing would be what I would make. Including a non-marring set screw to clamp the rod into the guide and prevent rotation and sliding could be a plus.

Just to get a sense of rod hardness, what does happen if you use a center punch and give the punch a decent whack with a hammer? (I am assuming you do not have a hardness tester).

Denis

 

[David916]

If you don't go for a carbide solution then use a 3/16" diameter cobalt drill bit.
Follow with a 1/4" HSS 4 flute cutter with some WD-40.
The holes will look much nicer than if you used a 1/4" drill bit.

I like this idea! I have a large cobalt drill bit set and can definitely do this and will give it a shot next weekend when the cylinders arrive. thanks!

If your center punch does not get a flattened end after trying to ding the rod, then the rod is soft and you do not need a die drill to do the hole. But a good cobalt drill bit with a split point will be worthwhile because it should last longer than a cheap bit.

Larry

Ah, great way to test the material. Ok, I'll give it a punch and see how rod accepts the dimple.

You say in your profile you are the owner of a small tool company. I have no idea what machine tools you have available. But making (or buying) a guide for a hardened 1/4" drill bushing may help you easily find center and reduce drill bit (or end mill) wander as you bore the hole. There are many styles available. A custom one consisting of a block of steel bored with a horizontal 1" hole and then accurately vertically drilled for the bushing would be what I would make. Including a non-marring set screw to clamp the rod into the guide and prevent rotation and sliding could be a plus.

Just to get a sense of rod hardness, what does happen if you use a center punch and give the punch a decent whack with a hammer? (I am assuming you do not have a hardness tester).

Denis

A drill bit bushing is a great idea. If drilling it gives me problems, I'll invest in a nice drill bit bushing. I'll test the hardness next weekend and will have the data. From what I remember from previous jobs, I had no problem with just fluid and a harbor freight 4 flute end mill. I was wondering if there was a better way to do this, and will try under boring the hole with a cobalt drill bit, then using a HSS 4 flute cutter and fluid.

 

[eKretz]

99% of cheap cylinder rods are soft steel .chrome plated ....very thinly chrome plated .........grind away the chrome ,and drill very easily .

Fixed that for you... Most of the high quality stuff is at least .050" induction hardened, usually more. Good luck trying to center punch that stuff. Bye-bye punch point on the first hit.

 

[john.k]

I had always assumed cylinder rod was hardenable .....but Ive found unless the rod comes from a Caterpillar or International machine,its soft ,non hardenable steel.......The bulk chromed and ground rod (apparently Germany is the source of this rod) you buy from a hydraulic supply shop is soft and has very thin chrome .....and rusts in the weather ....Now the 1960s and 1970s Caterpillar rod could be oxy cut into drawbar pins ,left lying in the dirt ,and never rust .

 

[john.k]

In fact ,I noticed just this week ,the bucket crowd ram on my Hyundai excavator has what looks like a case of pimples ......closer inspection is a mass of tiny dents under the chrome ......I stoned it flat to stop the seal being damaged ,but how long before it rusts now.

 

[David916]

Fixed that for you... Most of the high quality stuff is at least .050" induction hardened, usually more. Good luck trying to center punch that stuff. Bye-bye punch point on the first hit.

I've used a Titanium Nitride Coated M2 HSS end mill (harbor freight) and have drilled a tun of holes in these cylinders before without issue and still use the same bit.

My center punch is the 18C from Starrett, but I can't find out what material the point is made of. It's either hardened steel or tungsten carbide. I posted a question on Starrett's Amazon page and will see if they reply. I'm curious if it's harder than the M2 HSS end mill.

 

[David916]

In fact ,I noticed just this week ,the bucket crowd ram on my Hyundai excavator has what looks like a case of pimples ......closer inspection is a mass of tiny dents under the chrome ......I stoned it flat to stop the seal being damaged ,but how long before it rusts now.

I have a 50 ton cylinder that has scratches on the rod and it leaks. How did you fix the pimples, what does 'stoning' mean, and does it leak since the shaft diameter is slightly smaller after you removed material? Thanks.

 

[john.k]

Back in the day ,I used to fill hardchrome scores with stainless TIG ......big money spinner ......but heavy work ,cause some of the nuts are tightened to 1,000,000ft /lbs ..AND..loctited ........another interesting repair is the dipper ram on big excavators with arc damage from powerline contact.

 

[LOTT]

what does 'stoning' mean, and does it leak since the shaft diameter is slightly smaller after you removed material? Thanks.

The shaft shouldn't be smaller, the stone only takes off the high points.

 

[David916]

Oh wow, thank you for sharing

 

[Gordon Heaton]

I have a 50 ton cylinder that has scratches on the rod and it leaks. . .

Stoning will do nothing for scratches, gouges etc. except remove any associated protruding ridges.