o-ring groove in plate

[gerry maddenParticipant @gerrymadden53711]

Hi MEs,

I have an aluminium plate 4.7mm thick and it has a 25mm dia hole in it. I would like to machine an O-ring groove (around 2 x2) in the bore of the 25 hole. What I imagine I need is a boring bar with a parting off bit coming off the bar at 90 degrees to its axis.

I don't have time to make such a beast – even self isolation wont give me enough time to do all the jobs I have to do – so I'd like to buy one. Thing is, I can find on any of the popular sites anyone selling the thing that resembles what I think I need !

Would anyone be able to point me in the correct direction ?

Gerry

[gerry maddenParticipant @gerrymadden53711]

[S.D.L.Participant @s-d-l]

PH Horn do them but they are Spendy.

Steve

[clogsParticipant @clogs]

would have thought it'd be easy to make it urself…..

nice peice of round bar say 14/15mm dia….and a modified broken drill shank at the least for the cutter……

secured into a hole pre drilled into the shaft…..

no need for complication….it's only ally….

[JasonBModerator @jasonb]

If you can swing it on the lathe then a bar like this would do, on the mill you could hold in themil spindle and rotate the work on a rotary table

[old martParticipant @oldmart]

I have a couple like the one in Jason's post, 2mm and 3mm. They are the cheaper Chinese ones from ebay. They use the MGMN– inserts which are common and not propriety types. If using a mill boring head, then a ground down drill of the shank size to fit the head would work. If you have any parting off carbide inserts, then it would be possible to silver solder one to a steel shank to make a custom tool.

Buying one at the moment from a UK supplier might be difficult.

Edited By old mart on 27/03/2020 18:31:26

[OldironParticipant @oldiron]

So quick & simple to make from a piece of HSS or an old drill bit shank why would you buy one. As old mart says it may be difficult to get one delivered at the minute.

regards

[EmgeeParticipant @emgee]

If using a mill you could use a 20mm diam 2mm thick Woodruff cutter either with cnc or set-up on a rotary table.
You could of course also use the same cutting tool in the lathe with the plate mounted to a faceplate if you have enough swing.

Emgee

[HOWARDTParticipant @howardt]

What is the purpose of the o-ring. Could it be held in a counterbore into one face.

[gerry maddenParticipant @gerrymadden53711]

Such things do exist ! Great. And now I know what they are correctly called I have been able to search more sensibly and I see even Cutwell advertise them. Thanks all for your assistance.

Howard, the plate is actually part of a small propeller hub. I'm actually building a balancer unit for it but didn't like the fact that the plate was a clearance fit on the mounting boss. This would lead to a loss of balance, not much if one does the maths, but I cant forget such things especially when it can so easily be mostly eliminated. The O-ring will allow assembly but help maintain concentricity until the bolts are tightened is probably the most elegant solution – in my mind at least .

Gerry

[old martParticipant @oldmart]

What about axially drilling three or four holes in the edge of the 25mm hole and inserting o ring material to help self centring?

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