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Ideas for machining piston rods

badger84

Plastic
Joined
Mar 27, 2014
Location
wisconsin, usa
Hello everyone,
I could use some advice on the best way to make some chrome plated piston rods. I would like to purchase manual machines to do this. The rods are 3/8 in. chrome plated piston rods. The qty. is about 2400 pcs. at a crack a couple times a year. They are drilled and tapped on one end and blank on the other with a length of 4 inches +/- .001 What is the best way to manufacture these. I am not looking to spend 20,000 grand on equipment here. I work in a small shop and we would like to start making these in house.
I have a little manual lathe experience. I can figure that part out but I am not familiar with all the different types of lathes and machines out there.


Is a cold saw accurate enough to cut these to lenght? Band saw and then face them in a small lathe or just drill, tap and cut them in a small lathe. What type and brand of lathe do you recommend.

Also we might consider making 3/4 and 1/2 in chrome plated rods as well in varying length (4 to 12 inches) +/- .010 , drilled and tapped on one end with male threads on the other. 1/2-20 and 3/4-16 on the 3/4 in and 3/8-24 on the 1/2 in. These are made in Qty. of about 25 - 50 pcs. each at a time. Is it best to single point these or use chasers? What lathe would work for all the sizes 3/8, 1/2, 3/4

Any advice would be greatly appreciated.
Thanks
 
This story adds nothing, but I find it humorous-

We machined a couple piston rods (crosshead rods, more specifically) the other day. Someone didn't lube a compressor for about 15 years and when the glands dried out they eventually wore about 1/4" off the hard chromed shaft.

Oops.
 
A chucker with a 5C nose would and an automatic threader would be efficient at that. I would go with a turret lathe with a automatic die head. You don't want to be single-pointing that many on a manual machine. Outfit either with a rear cut-off and you have your length too.

Precutting the length save on labor at lathe rates but it means having to chuck each piece twice. On the dash numbers that only have features on one end do the cutting on the lathe to save a chucking. It helps to have a stock puller rigged up on one of the turret positions.

There is a whole class of machines that are not CNC but will automatically pop this kind of work out with great ease; once they are set up. You could put one in a corner for just that job. On the other hand, CNC lathe could be doing other things while you are waiting for that one job to come in.
 
What's the material? It's chrome plated, but what's the base and is it hardened
What's the finish specification? If you've got to hold a 4 finish on that rod, you sure don't want to be dragging it through a collect.
What size and how deep is that tapped hole? It makes a big difference.
What exactly is the length specification? You say +/- 0.001" in one place and +/-0.010" in another.
What is the finish specification for the end of the rod?

You sure aren't going to do this with 1 machine and IMO, your expectations of doing it for less than $20K is probably off also.
JR
 
The material is an issue as far as cutting it. I'm assuming 1045 or 10v45 with standard chrome thickness? That chrome will tear up a bandsaw. D&Ting one end shouldn't be a problem because you won't have to deal with the chrome, but holding the work might be tricky.
 
Unless the chrome is horrendously thick, a bandsaw won't even notice it's there. Standard chrome hydraulic rod is .0015 chrome. You can get thousands of cuts out of a bandsaw blade if you are anywhere near careful. Just use a good quality blade with coolant and keep the speed reasonable. Hardened chrome rod is yet another matter. If it is induction hardened, under the chrome, there will be about a 1/8" thick hard case that is just not going to cut. Mark your cut, go around it with a cutoff wheel and proceed. Other option is heating until red hot to anneal the section you want to cut. After that, it's just like standard rod. Your life will suck trying to machine it in the hardened state, as well. Carbide is the only thing that will cut it and it's very slow going, even then.
 
Thanks guys,
The material is 3/8 in. TGP C1045 chrome plated rod stock. 4.485 long +/- .001 and #21 drill .625 deep and 10-32 tap .375 deep on one end. square up the ends.
I am sure the guy that did these before cut them in band saw no problem. Then he finished them in a lathe. I was just wondering if there was a better more efficient way. Just trying to get ideas.
Thanks again.
 
Get a price quote from a hydraulic parts supplier like Bailey,for pre cut material before you proceed.You may not be able to buy and cut in house as cheaply.Then all you have to work on is the one end.
 
Mike, for my own personal curiosity: for OD threading on the chrome plated but not induction hardened material; do you take a skim cut with carbide and then thread? or spin in a grinder first to remove chrome in the threaded area? or just go ahead and start threading, probably not with HSS, though?

Thanks,
smt
 
The chrome is usually within a couple thou of dimension, so I like to peel a few thou off before threading, just for the proper thread fit. You'd have a full V profile if you didn't. If you take a good bite (no less than .025) and get under the chrome, HSS works just fine. You are cutting the metal under the chrome and the chrome is so brittle that it just flakes off as the chips form. For just skimming the chrome off, it works better to go to carbide.
 
If this job came into my shop I would be giggling on how simple of a job it is. If you have to ask how to do this, maybe you should have a local shop quote you a price, then tack on a few bucks and do it that way. You will not have to buy an machine or wonder how to make these parts.
 
Unless the chrome is horrendously thick, a bandsaw won't even notice it's there.

A hard-chrome plating has 850 to 1050 HV. This translates to 64,5 HRC for the 850 HV. A saw (except abrasive) will just skip until the blade is dull. Doesn't matter how thick the plating is.
For HSS, we talk about HRC 62. Just as a reminder.


Nick
 
My first job out of high school was working for a hydraulic cyl manufacturing co.... Standard chrome plated rod cuts very easy and even the better grades cut with no problem with a normal blade. It's the case hardened rod that you have to worry about.
 
Nick, how often have you used a bandsaw on chrome hydraulic rod? Your calculations are wonderful, but totally wrong. I know this because I have probably cut enough hydraulic rod on a bandsaw to reach from here to where you are. It is a large part of what I do for a living. I work in a shop that is a combination chrome plating shop and hydraulic cylinder shop. There is no issue with cutting hydraulic rod with a bandsaw unless it is induction hardened. FACT. Your opinion is just that, an opinion and it is erroneous.
 








 
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