[PSUBS-MAILIST] O-ring groove machining

Sun Feb 26 15:58:54 EST 2017

Alan,

They call it emery Tape or metalcloth here and it comes in rolls about 300mm diameter.  You can get different widths but we use 40mm width and 120 or 150 grit. Paykels, Trade tools, Machinery house, Chevpac.

Now you have had a few hours on your lathe you should come out to see how to do things properly.  It takes years to become a good machinist.

The first thing in your workshop should be a bench grinder to sharpen tools.  As you are mainly into aluminium then you are best to use High speed steel and then you can make your own grooving tools etc.  IT is too costly to get carbide for all the different things you want to make, especially if they are one-offs.

You are trying to make critical parts so you should enrol at Unitec for a machining course.  Otherwise you can come out and I will give you a few tips on what is available and how best to approach it all.

Rgds, Hugh

From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Alan via Personal_Submersibles
Sent: Saturday, 25 February 2017 4:46 PM
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] O-ring groove machining

Hi Alec,

not quite following you. Do you mean cutting a strip of sandpaper

& rolling it length ways & taping it? I have just been using my hands

if it seems safe enough. Did lose a finger one time but not on a lathe :)

Alan

Sent from my iPad

On 25/02/2017, at 4:19 PM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi Alan,

Get yourself some rolls of sandpaper. Not sheets but rolls, about an inch wide. When you're done turning your piece, crank up the speed a bit and put a length of tape around it. It allows you to polish it up while keeping your hands away. Go to your fine tape and then spray with coolant for the final polish. I can't think of anything I turn on a lathe that I don't use tape on. Ah, the only exception is plastic. 

Best,

Alec

On Fri, Feb 24, 2017 at 8:52 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Thanks Brian & Hank,
it was the outer egdes that I left sharp.
It didn't cut nicely, it left a raised mound on the edge that I removed with a facing tool.
I will either look  in to a specific groove tool or better equipment for forming the
tool as these are taking too long :(
Alan

Sent from my iPad

> On 25/02/2017, at 1:49 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Don't need carbide for aluminum, did it cut nicely, aluminum likes high speed
>
> brian
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
> To: personal_submersibles at psubs.org
> Subject: [PSUBS-MAILIST] O-ring groove machining
> Date: Sat, 25 Feb 2017 12:41:39 +1300
>
> Am cutting some small o-ring grooves in aluminum, 3.4mm x 2mm deep for
> a 2.5mm D o-ring. ( 10th of an inch) What is the best way to remove the sharp
> corners of the grove? I have read that you can spin your work in the lathe
> & sand with 200 & then 400 grit sand paper. Is this right?
> Have been having fun making the tool for this & don't think I have done a
> good job! Am I best to buy a carbide tool specific for this job.
> Thanks, Alan
>
> Sent from my iPad
>
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