O.T.but...

[orange_glow_fan]

I need some advice. I need to drill a hole in the center of a 3" PVC cap. It's to be the spinning hub of a yard art project and this forum has some of the best 'fabricators' I know so I thought I'd ask.

Obviously it needs to spin with no wobble. Unfortunately I don't have access to a lathe so I need an alternative...

Thanks for your time..

Kerry

[barefoot1]

Kerry,

Is the surface of your 3" PVC cap flat or convex? If it is flat you can use a center head on a scale to locate the center if you have a center head. If you don't have a center head and it's a flat ended PVC cap just draw two intersecting lines to find your center and then drill the required hole. 

[Tidak Ada]

You'll need a lath! (or a friend who has)

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com]
Sent: dinsdag 22 juli 2014 12:48
To: neoni...@googlegroups.com
Subject: [neonixie-l] O.T.but...

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[gregebert]

Do you have a drill-press ? I've turned a few items on my drill press with satisfactory results.

Other than that, I would place the cap (open-end pointing downward) over a small-diameter woodscrew pointing straight-up, and balance it as best you can. Once you find that spot, press the cap downward on the nail to make a dimple in the plastic cap. Then, choose drillbit slightly smaller than the woodscrew and drill your first hole at that spot.

Screw the woodscrew into the hole in the cap, and try spinning it like a top. If it wobbles too much, you might be able to nudge the hole in a different direction as you change to larger drillbits getting to the final hole-size.

[Nick]

Two bits of ply glued at 90 degree to each other.

At one end, glue a strip of wood at 45 degrees to the other two such that one side of the strip intersects with the vertex of the two other pieces.

Sit your round cap in the "V" and use the strip of wood to draw a diameter.

Rotate the cap and draw another diameter. Do this a few times.

Where the diameters meet in the dead centre of the cap. The picture below gives the idea - its actually a woodworking tool but should be obvious...

HTH

Nick

[Arne Rossius]

On 22.07.2014 18:00, Nick wrote:
> Two bits of ply glued at 90 degree to each other.
> At one end, glue a strip of wood at 45 degrees to the other two such
> that one side of the strip intersects with the vertex of the two other
> pieces.

And here's a DIY version of the tool you described (the page is in
German but the pictures should speak for themselves):
http://www.zabex.de/site/helferlein.html#mianvoru

Of course, it is best to use a pen that draws as close to the guiding
edge as possible.


Best Regards,
Arne

[Tidak Ada]

Nevertheless not good for an fast spinning cap.

Really a lath is the best tool to do the job. If there is no one available in your environment look for some workshop who has one and ask them to drill the hole. Will cost you a couple of bucks, but is worth the effort.

Some vibrations will occure anyhow in a moulded cap. In case these aren't allowed, it will be better the whole cap will be turned and drilled in one process. Will cost more but makes you more content.

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Nick
Sent: dinsdag 22 juli 2014 18:00
To: neoni...@googlegroups.com
Subject: [neonixie-l] Re: O.T.but...

[Quixotic Nixotic]

I use a fairly cheap device found in most UK hardware/tool shops as part of a sliding rule set. In my case it included just the sliding square on the left and the circle centre finder on the right. The middle piece is an angle finder/setter.

You use the centre finder in exactly the way Nick described - place the angle around your circle in several places and draw lines along the rule. Where the lines intersect is your point. Punch it and drill.

John S

[petehand]

Is THAT what the V-shaped thing is for? I'm indebted to you sir - I never knew what it was for.

[Tom Harris]

Even easier, all you need is a flat surface and a pen. Simply use a book to hold the pen at about half the diameter of the cap off the surface.
Books work well as you can adjust the height simply by adding pages. Then put several marks with the pin at different positions of the end of
the cap. Your centre is in the middle of the marks, which if they are close together is easy to get. Simple.

Tom Harris <celep...@gmail.com>

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