Beginner's questions on TruLine boaring bar.

[dunegoon]

I recently picked up a nearly new (used but unused) Tru-Line boring bar complete with camshaft and thrust cutter. I have experimented on a couple of junk cases with the cutters set via the supplied micro-adjuster tool and that part seems to work fine.

Would anyone care to explain how (much) to custom adjust the cutters to suit a particular set of main bearings? For example, say I measure the #2 bearing O.D. -- then how much smaller than that measurement should the cutters be adjusted to?

Or, say I find the crankshaft is otherwise fine but polishes out to -.0005 undersize. Could I fine tune the bearing clearance with a little more "crush"?

And, is it possible to use this tool on a type 4 and/or a Wasser with the use of some sort of adapter bushings? I could probably turn out some adapters on my lathe, but I seems I should ask for good ideas first.

[dunegoon]

Answers to these questions are closely held secrets, I guess...

[ProctorSilex]

That tool is not something the average VW owner has and the few who do are probably making money off of it. You might want to search the Samba if you haven't already. I have read about these tools there and it usually turns into a debate about the tool itself rather than discussing how to use it, but somebody ought to answer your machining questions.
I have the Portatool. I saw a youtube video a few years back, but they gave no details and they zoomed through the cuts which was probably not good. I figured that I would just figure it out myself when the time comes.
You are probably getting into frontier territory with the T4 adapter.
The basics of bearing bores ought to be available in machining and engine blueprinting books. Maybe even a machinist forum. Have you tried looking in those places?
I would think bearing crush to be a bad thing, but the magnesium might be soft enough to require an interference fit.
Please share what you find.

Truline thread: I only read the first page. Maybe they get into the bore sizes later?

[dunegoon]

Awesome! Thanks.

[fusername]

use the cam cutter to check every bug case you use. most have sagged a bit in the middle and need a refersh. dont go next size up if possible, just clean it up at stock size and you should be good.

[dunegoon]

For sure, every case I have tried it on has shown a need in the center cam bearing. I also used it on a type 4 and it helped there also. Since my original post, I have purchased a second TruLine bar and I am in the process of carefully setting one up for .50mm and the second for 1.0mm. I also built a very accurate depth micrometer that sits in a saddle over the cutters to ensure correct settings. It's patterned after one I saw on The Samba. There is no substitute for practice, so I now have cases to practice on to ensure I have the settings correct. I'm thinking I am moving from apprentice to journeyman territory.

Sigh,... just noticed a typo in the original post should be "boring bar" not "boaring bar".

[SlingShot]

First, make sure the case is not warped at 10 ftlbs on the main 6 case nuts. If it's warped you are wasting everyone's time.

The best way to get proper measurements is to set your bar close to what you want. Run the bar, loosen the case nuts on the front and rear , leave centers tight if possible. Remove the bar fixtures, jimmy the bar out of the case. Re torque nuts. Check bores with a dial bore gauge . Now you know for sure what size you're cutting. I personally don't adjust the cutters on the Truline, its a little tricky setting them unless you have a custom mic, or trial and error with cutting a case.
I also check bearing clearances with bearings installed and torqued with a dial bore before a build. After doing this you'll have some that are tighter than others. They may be good for undersized cranks. If you try and over crush a bearing to achieve a smaller size it will egg shape on you, that's no good.

I'm unsure on the T4 setup. If the spacing is right, which I believe it is , you would need adapters.

Run the center cam bore tool, on every used case.

Hope this helps.
Chris

[dunegoon]

SlingShot: If this was Reddit I'd upvote your comment. Thanks for the tips! I'll be looking in my Enco catalog for a dial bore gauge. I have snap gauges but I don't trust that method for this precision level. The supplied measuring sleeve seems pretty nice, though. I was thinking about having a "real" machinist make me one for 1.0mm

[SlingShot]

Enco has some decent stuff or Ebay.

If you have a trustee micrometer set and a dial bore, you're set.