Truline feed mechanism

[Danpa]

I'm in the process of making my own line bore setup.

What I need to know is if the information I was able to find about how it works is correct. I read that the feed mechanism is hydraulic and is based on a closed cylinder, filled with oil, fixed to the case with a piston inside that is attached to the boring bar, that has a spiral groove cut into the outside diameter.
As the piston spins, oil is caught by the groove, and as the oil travels to the other end of the piston, it fills up the area behind the piston. Thereby, "feeding" the piston slowly forward in the cylinder.

Is this correct? Anyone have any pictures of the piston?

It sounds like it would work but, I really don't feel like making the necessary parts if this is just hogwash.

Thanks,
Dan

[raul arrese]

No, the truline doesn't have a hydraulic feed , it uses a screw feed . If ur gonna make ur own feed , make it like a lathe .. smooth and more precise .. the hydraulic feeds jump around , at least that's what I heard
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[Dale M.]

Feed is mechanical...

Some clues to be found here...

http://images.lmgtfy.com/?q=true+line+boring+bar

Dale
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[Brian_e]

I would imagine you already have a lathe if you are considering this project. If you have at least a 13" swing, make a heavy bar with the cutters, a way to fix the case to the carriage, and use the lead screw on the lathe to feed the case across the bar. The bar is chucked on one end and centered with the tailstock. You will need to make some very accurate end bushings with this setup or a portable unit. With accurate bushings and a sturdy bar, this should be more ridged then a portable unit, and you can fine tune your speed and feed rate. Pretty sure this is how rimco has always done their cases.

Brian

[raul arrese]

[Danpa]

Thanks for the replies!
Yes, I have access to several engine lathes at work. Along with the usual Bridgeports, grinders, edm wire machines, etc. I'm a tool and Die maker by trade.

I did already make a fixture to hold the case on the cross slide, with the case sitting on it's side, being held to the fixture using 2 of the cylinder bores. I figured I'd shim the case to get the flange face and OD that fits into the trans indicated in for height and perpendicularity.

There is only 1 glitch in this idea. The company I work for is totally fine with "government jobs", but, I could only do this during my lunch breaks (1/2 hour) or before or after work (20 minutes). When breaks or lunch is over, the machines have to be open for regular work. By the time I would get it half indicated in, I'd have to tear it down.

This is why I want to make a portable bar like a Truline, to do it at home.

Dan

(I do have a enco bench mill at home, unfortunately it doesn't have power feed and I don't have a lathe)

[Danpa]

Well, I think I figured out the mechanism.

It appears that it involves 2 threads, of different pitch, one LH and one RH.

I had a need for this setup for very precise measurement adjustments on a machine design about a year ago and kept thinking "I have to remember this, someday I might need it".

And Presto! It looks like today is that day!

Dan

[nsracing]

Do you need a TruLine? That is the question.

I may have a spare feed and 1 chrome bar I can separate w/.

I have been meaning to make some nicer feeds for the TruLIne w/ more robust leadscrew..like ACME threads -just like in an engine lathe.

The TruLIne is a real wonder in its design. The power is from a single source. The bar will spin and feed at the same time w/ the smallest advance.

With only 1/2 hour to work w/ that is hardly enough to clean up the table and tram the workhead on the mill.

To build this unit from scratch, you will need several machines: engine lathe, mill, deviding head, and all the toolings you can muster.

I am in the process of rebushing the feed on the spare TrulIne and machining a fresh end bushing for it.

PM me if interested.

[Danpa]

Well, I don't REALLY need a Truline. I could just send it to a VW machine shop or buy a new case.

But, with some of the machine work I've seen done over the years, both to car parts and even at work, I'd rather do it myself. (my current job is the 8th machine shop I've worked in over the last 38 years, including 2 defense contractors)

And this is in no way a dig to you or anyone else that does VW machining here on the samba, just to be clear.

As far as tooling and machines, here at work the only things we don't have is a chrome plating area and a gear cutting department. Although I've cut gears on a lathe before.

We've got;
Milling, drilling, lathe, grinding, jig boring, polishing, (cnc and manual).
Wire feed EDM machines (like a band saw only using wire for making die parts)
Punch presses, full sheetmetal shop, welding, stainless and bronze investment cast foundries.
Alloys are A-2, 300 and 400 series stainless, cast iron, aluminum, bronze, 17-4, stellite, cpm 10v, mild steel, carbide.

And, like I said, I'm in Tool and Die, so I pretty much have a free hand to use what I want.

In other words, it's GOVENMENT JOB CENTRAL!

And if I really wanted to, I could take 4 hours of vacation time, and stay and work on my own stuff.

Dan