Drilling rod

[TonyF]

Can I drill a hyd cylinder rod with a HSS or cobalt bit? Or, are the rods hardened and I need to use carbide?

I have an existing cylinder with a 3/4" hole thru the rod, I would like the hole to be 13/16". But depending on the answers here, I may like it a lot less and take a different approach.

Anyone know the alloy that is usually used for cylinder rods?

Thanks

Tony

 

[Brad_Blazer]

The rods usually have a hard chrome coating that cannot be easily machined but the base metal should be machinable. The drilled end probably has no chrome. You can use a file to judge it's hardness.

Slightly boring a large hole with a twist drill can be tricky. Make sure you have good alignment and securely clamp the piece. Don't let the drill feed itself in and get stuck.

 

[kennyd]

The rods usually have a hard chrome coating that cannot be easily machined but the base metal should be machinable. The drilled end probably has no chrome. You can use a file to judge it's hardness.

Slightly boring a large hole with a twist drill can be tricky. Make sure you have good alignment and securely clamp the piece. Don't let the drill feed itself in and get stuck.

Correct. The rod itself is not hard-only the chrome outer layer.

 

[David s Von Gieserbrechta]

The base metal of hydraulic ram is relatively soft and machines easily once you remove the chrome coating.

 

[Wayne County Hose]

Exact alloy I am unsure of. You have an existing bore so it shouldn't be a problem. If memory serves me right the hardening goes past the chrome but not by much. If you need this to be exact take it to a machine shop unless you have the proper equipment. If tolerances are + or- a country mile, do it at home.

 

[TonyF]

Thanks for the info everyone, they confirm what I thought. Still haven't decided, have to wait for the weather to warm up a little before I can get out.

 

[skipmarcy]

When I built my toplink cylinder about 6 years ago I cut the 1 1/2" rod off to my spec with a hacksaw - was the only thing available to me at the time. Not something I would like to do again.

 

[troutsqueezer]

I don't know how accurate in size you want the hole to be but I do know you cannot drill a precisely-sized hole with a standard drill bit. A 13/16th drill bit will always drill larger than 13/16ths. This is probably not something you are set up to do but a machinist would underdrill the hole by one size and then use a reamer to bring the hole up to the finished 13/16th size. Reamers can be bought for around $15-30. You use them at a slow RPM.

FWIW.

 

[KWentling]

Most cylinder rods are low carbon mild steel with just a flash of chrome of .001" or so. The chrome is hard on bits, even carbide ones. Just grind the chrome off if its present where you are drilling. When we make replacement rods we usually make them of induction hardened, chrome plated, which is much better at resisting bending and wear. Cat equipment uses this same material for its cylinders. The hardening is generally .060" to .090" deep. I doubt you will run into that though. If you have a GOOD drillpress, you could probably do this yourself, but I would recommend a machine shop do the work. $15 might buy you a 13/16" drill bit, but reamer of any quality will be double that or more.

Kim

 

[wdchyd]

To test for Induction Hardened, take a center punch and whack it where you want to drill it....if it dulls the punch then it is hardened.....if it dings easily then it's just regular stock (Cold Roll 1045).....drill it with HHS drill bit and coolant.....(water hose trickling constantly on bit if no coolant avail)

If it's Induction Hardened then take an Oxy/Acet torch and heat up the area to lightly glow red on both sides to drill......(as mentioned the hardened material is only about .100" thick).....let it cool slowly and the hardening will normalize to drill easily.......

Also to use a 3/4" pin we bore out .015-.020" oversize for a running fit.....Perfect fit.......:thumbsup: