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mike4
12-25-2010, 03:38 AM
I have several full hardened ,unknown type as yet ,steel pins which have to be heat treated to bring them back to a machineable condition .
The customer requires the grease channels to be extended and three 1/8 " holes drilled to allow grease to be available at each end as well as the already machined central delivery point.

Several have been replaced due to lack of lubrication at the ends .

Buying replacements and having them shipped at this time of year is not an option as the machine returns to work Monday/Tuesday .

I hope everyone is having a merry christmas and next year brings enough work to keep us all occupied in our various pursuits.

Any suggestions ?????

Michael

Walter
12-25-2010, 03:58 AM
If the pins are hardened and ground (making an assumption here) your probably best off to skip annealing and either have the holes popped with an EDM or just drill them with carbide in their hardened state.

Black_Moons
12-25-2010, 04:15 AM
walter makes a good point, You are not gonna end up with the same part after annealing and rehardening, It will warp.
It was likey hardened ground for a reason (accuracy, strength), and you can't regrind it afterwards or it will be too small.

mike4
12-25-2010, 04:34 AM
If the pins are hardened and ground (making an assumption here) your probably best off to skip annealing and either have the holes popped with an EDM or just drill them with carbide in their hardened state.
Thanks , Ill try drilling them with a carbide bit , nothing to loose , and if it works may save time as I have 8 pins to get ready by lunchtime tomorrow.

I dont have access to an EDM yet , they are a bit hard to locate , new or secondhand where I am situated .

I' ll try to post some pics of the test one if I can get them on to photoshop.

Keep you posted , again thanks.

JCHannum
12-25-2010, 07:11 AM
Is it possible to make new from drill rod (silver steel) and harden. Annealing and re-hardening an unknown steel is problematical at least and unworkable at most.

.RC.
12-25-2010, 07:43 AM
I agree with the others, either drill them as is with carbide or make new ones... Of course making new ones may not be feasible given no shops will be open until wednesday at the earliest, unless you have steel on hand..

Given the weather warning out for this area, I doubt the machine will be back at work on Monday.... Unless it is a boat :D

rohart
12-25-2010, 09:14 PM
Hiow about telling the customer you're going to make temporary pins, and do it out of mild steel. They should last long enough for them to get the proper things delivered, or for you to get a second set made in drill rod, hardened and commercially ground to size.

Just a thought.

mike4
12-26-2010, 10:49 PM
I agree with the others, either drill them as is with carbide or make new ones... Of course making new ones may not be feasible given no shops will be open until wednesday at the earliest, unless you have steel on hand..

Given the weather warning out for this area, I doubt the machine will be back at work on Monday.... Unless it is a boat :D

It's down for maintenance , has to be moved before site is under water , we tried MS pins but they only lasted about 60 hours and they looked like they had been in service for years .
The bushes were not sealed originally but last time there was a major overhaul bushes were made with seals which kept 95% of the fine dirt out and made bush replacement almost a thing of the past ,this set has laste 5 years and is only just showing wear.

The pins were originally made by Cat for a midrange dozer and have lasted quite well , when I contacted them for replacements these are no longer supplied , just soft core case hardened ones are available .

This is the reason for the mods ,to attempt to prolong the service life until a set of replacements can be made.

I have found a damaged one which I will practice the drilling on , I have sharpened a cheap masonary bit which is surprisingly long enough to extend the central gallery to the required depth .

The machine is being re-assembled so I will have a bit more time to play.

I got told that I cant take pics of machine as the site wont allow .

I will hopefully post some of the drilling , if i can get them to load.

Michael

.RC.
12-29-2010, 11:31 PM
How are you going Mike? Hope you are safe and dry...

For those not in the know the town of Emerald is expected to go 80% under water from rains that fell on christmas day and boxing day

http://www.abc.net.au/reslib/201012/r695806_5284139.asx

http://www.themorningbulletin.com.au/story/2010/12/30/80-emerald-flood/

The flood is greater then the 2008 one that some of you may remember this picture came from http://www.agmates.com/images/Drag-line-2.jpg

Rich Carlstedt
12-30-2010, 04:55 PM
On a break down job like yours, I have drilled pins with a 1/8" masonary bit.
Cranked up the RPM to 4,000 more or less
Put a deep cake tin on the drill press table filled it with water, and then put a drill press vise in the pan and drilled the pins. The water was over the top of the pin to cool the carbide's solder joint
Be careful on "breakout". you may want to drill almost through, and then fill the hole with aluminum (used a welding rod) and drill from the other side.
The easily removed "plug" prevents the carbide from shattering when it sees a unbalanced or open hole.

Rich

Rich Carlstedt
12-30-2010, 04:56 PM
If you think the above is too harsh on the drill vise, just dunk it in Alcohol after, and all the water will be removed by the alcohol

Rich

Cami
12-31-2010, 01:27 AM
Have any of you guys used expander pins? http://www.expanderamericas.com/

I've never used them, run into anybody who uses them, or found them on any machine I've serviced, but they advertise in a newspaper I read and I'm curious. If not for your time crunch, mike4, maybe it would work for your client.