Can anyone machine a wee cylinder of metal for me? (NLC)

[graeme]

Hi SE engineers/CNCists,

Does anyone have the skills and tools to manufacture for me a wee cylinder of aluminium, approx 30mm x 30mm? (I'll confirm the exact size.).

The problem I'm solving is that I have is a set of Subaru bucket-type cam followers which are out of tolerance since the heads were stripped down, and won't go back together with the correct valve clearances. Most seem to be slightly too thick (possibly due to lapping the valves), so I plan to wet-and-dry the faces on a flat surface, but measuring the exact thickness of each bucket is tricky because I can't get a micrometer to fit over the side of the bucket. Robin's clever idea was to make a solid cylinder to slip inside the bucket and sit on the inside face where the valve touches, of a height larger than the bucket itself to clear the sides, thus giving a reference point to measure from with callipers or micrometer.

Subtracting the known height of the metal cylinder then gives the thickness of follower. This will allow me to wet-and-dry a bit off the face and remeasure quickly and with repeatability.

My non-engineery thoughts (happy to be told I'm talking p*sh):

- The diameter tolerance isn't important, say +/- 0.1mm, as the inside face of the buckets isn't finished, and they vary. I'll try to find the minimum internal diameter by experiment before confirming the cylinder diameter. How tight the fit should be, I'd take advice on.
- The height is not important, but must be taller than the bucket, so 30-35mm would do nicely.
- The top/bottom faces must be as parallel as possible to help with repeatable measurements if the cylinder rotates. Valve clearances are +/- 0.02mm, so thousandths count, but I don't need to see my face in it.

Happy to pay time, materials, postage + beer, or whatever works for you.

Thanks in advance, and also thanks to Robin for the idea.

Cheers,
Graeme

[BiggestNizzy]

Should be easy enough to make.

I know nothing about what your trying to measure but my guess is your looking for something to fit inside the bucket so that you can measure the thickess of the inside bit?

I would be happy to make a small pin but I would make it from steel for ease of manufacture.

[woody]

Currently have an apprentice who seems a little too focused on making hub-centric adapters to fit Porsche wheels to a 1.2 Polo, so can probably get him to make something.

Why don't you use a socket or another spacer that would fit inside the buckets?

[graeme]

Excellent, thanks guys.

Steel would be fine. I just assumed aluminium would be easier to work with. See, I know nuffink!

Woody, thought of that, but nothing suitable to hand, and I need it to be very parallel on the flat faces. A reasonable fit on the diameter will make it easier to work with too.

I'll confirm exact diameter tonight and let you know.

Cheers guys,
Graeme

[robin]

A socket won't give repeatable measurements at the +/-0.02mm level as neither face is machined (they are just cast, I think). You could achieve the same accuracy just measuring the overall face-to-skirt height of the lifter.

The idea is as follows:

Measure clearance from lifter to cam and compute how much material to remove from face to make it fit.
Remove lifter from engine.
Insert spacer and measure lifter-face-to-shim-face with fancy measuring dials; repeat a few times to make sure it is repeatable.
Subtract the amount of metal to remove from that measurement and that's your target.
Rub lifter on some wet-and-dry to remove material whilst trying to keep it as flat as possible - flat surface required!!!
Periodically measure progress to see how much more material there is to remove.

Repeat for all 16 lifters or until dead.

Cheers,
Robin

[graeme]

Can anyone think of a metal slab that's sufficiently flat for the job, but easy to come by?

Anvil, or jewlers block or something? The cheaper and flatter, the better!

[Danny T30TUS]

Hey Graeme,

Perhaps try looking for a slip gauge or combination of. Various grades of accuracy exist for slip gauges and they are available in different lengths and you also have the ability to attach them together to obtain your required height.

Even the lowest grade would probably be accurate enough for what you are doing.


Danny

[woody]

Can anyone think of a metal slab that's sufficiently flat for the job, but easy to come by?

Anvil, or jewlers block or something? The cheaper and flatter, the better!

Anyone going Ayrshire or Glasgow to Abz soon? I have a 2x1x10" slip I could send you up.

[BiggestNizzy]

If woody's slip won't do you should be able to pick up a piece of gauge plate (ground flat stock) reasonably cheap. From a local engineering supply firm

[robin]

Can anyone think of a metal slab that's sufficiently flat for the job, but easy to come by?

Anvil, or jewlers block or something? The cheaper and flatter, the better!

Given you're going to place the wet-and-dry or similar on it, micro-flatness not really relevant. Pretty much any old nominally flat slab of steel (or glass!) will do.

See Dave Andrew's page for a description of his technique, which is designed to tidy up hydraulic followers, but basically the same problem you have:

http://www.s262612653.websitehome.co.uk ... efollowers

Cheers,
Robin

P.S. According to google, there are blocks designed for this purpose, e.g:

http://www.suttontools.co.uk/forming/pl ... locks.html

[graeme]

Great help guys, thanks.

Danny, I'm not sure if you're suggesting a stack of slip gauges instead of the cylinder to take measurements from, or one large slip as a grinding block? Either way, good ideas. I actually have a 50mm calibration stick thingy for my micrometer that would do the trick, but it's a 3 handed job, and I can't get any repeatability. A custom pin will be much easier to work with.

I like the sheet of glass idea as a grinding surface. Sure, it won't be perfect, but probably good enough, and better than doing it on the bench.

I hesitate to suggest this, but I do have a very nice set of Japanese whetstones (200-10k grit) for doing my kitchen knives. I presume you're all at this point sucking air through your teeth, and that they'd make a lovely job of the grinding but won't be flat enough for this job, so wet-n-dry on a mirror is the better idea?

Spec: Internal diameter of the buckets by measurement is around 31.8mm. I think a cylinder of diameter 31.5mm, +/- 0.1mm would be ideal. 30mm is tall enough.

All vendors should submit quotes with a project plan, quality plan and supplier document schedule via the project office by midnight last Thursday. .

Cheers,
Graeme

[graeme]

I've got a possible offer up here in Abz, pending confirmation, so don't get your tools out just yet (arf!). I'll report back.

Cheers,
Graeme

[graeme]

Sorted locally, thanks everyone! Gotta love SE!

[campbell]

Can anyone think of a metal slab that's sufficiently flat to lie down on in a darkened room when I drop all the measured followers on the floor again?

Fixed that for you, big guy

Enjoyneering. That's what you're doing there.

[graeme]

Many thanks to Graham (Kinger) who dropped off the required item last night. I tried it out, and it works a treat, and all measurements across the faces are easily within 0.01mm. Perfick!

Thanks to all who advised, helped, offered, and especially Graham for not only getting it made, but delivering to the door.