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Pherdie
07-09-2009, 12:41 AM
My 5 year old Jet lathe (aka: "Leakin' Lena") is in need of serious attention. I'm tired of the puddles, rags and constant refills. It's time to tear this lathe down and attempt to stem the flow of oil. So I sit down with the manual and list out every gasket, seal and o-ring. I then summarize the o-ring requirements and then go look on the Internet for sourcing for specified metric sizes like 10 x19, 14 x 2.4, 20 x 2.4, 30 x 3.1, 40 x 3.1, etc. I can't seem to identify a single metric o-ring replacement on any of the replacement charts I found! Are the mentioned, called for sizes all non-standard, is some kind of ID/OD conversion required, or am I missing some other aspect? :confused:

Jet does sell the rings, but I'm hoping to find a better grade of rubber and avoid re-doing this job again in three years. Probably if it's Metric it will be Chinese anyway??

Fred

tattoomike68
07-09-2009, 12:50 AM
O rings are cheap and come in all sizes, buy 3 just for fun. there is not a size that cant be made or found. I worked with hydraulics for years and there is not a size that cant be found or made. big ones are just cut and superglued to size.

Are you sure the lathe is not overfilled and blows its load when it gets warm at running temp?

doctor demo
07-09-2009, 01:01 AM
P M sent
Steve

miker
07-09-2009, 01:47 AM
Fred, what is the model number of your lathe?

I have one of the generic 12 x 36 Chinese gems and had to cure a couple of leaks.

This thread is worth reading completely also, and particularly from about the 10th post down.

http://bbs.homeshopmachinist.net/showthread.php?t=3117

Rgds

Machtool
07-09-2009, 04:53 AM
I then summarize the o-ring requirements and then go look on the Internet for sourcing for specified metric sizes like 10 x19, 14 x 2.4, 20 x 2.4, 30 x 3.1, 40 x 3.1, etc. I can't seem to identify a single metric o-ring replacement on any of the replacement charts I found! Are the mentioned, called for sizes all non-standard, is some kind of ID/OD conversion required, or am I missing some other aspect

These are all stock standard JIS – Japanese standard O-Rings. Very common and widely available down here.

Table of them here.
http://mdmetric.com/tech/jisorsize.htm (http://mdmetric.com/tech/jisorsize.htm)

The description from the manual is giving you the nominal Inner Diameter and the section. These come in a J.I.S P & G section. Your 10 x 1.9mm is a P10, 14 x 2.4mm is a P14, 20 x 2.4mm is a P20, 30 x 3.1 is a G section, hence a G30, 40 x 3.1 is the same – G40.

You add you material and shore hardness to the end of that. Most normal would be N70 – Nitrile 70 shore.

Those aught to be available from any good O-ring supplier, seal or bearing house. No need to convert them, Just find one that supplies to the J.I.S standard and ask for them by the P or G size and number. Its actually a really nice system, where the compression is built into the ring so that they normally end up running on nominal shaft and gland sizes.

Regards Phil.

Pherdie
07-09-2009, 09:28 AM
Are you sure the lathe is not overfilled and blows its load when it gets warm at running temp?

No, I don't believe so. This situation has degenerated over several years. I have also previously replaced some original o-rings and found they were cut on non-relieved edges during installation.

Machtool: Your information is much appreciated and appears to be just what I needed to resolve my issue.

My thanks to all who responded.

Fred

bgott
07-11-2009, 12:28 AM
Now I'm going to have to dig out that Harbor Freight metric O- ring kit I bought a few years ago and check and see if the O- rings in it are something useful.

Machtool
07-11-2009, 01:17 AM
Now I'm going to have to dig out that Harbor Freight metric O- ring kit I bought a few years ago and check and see if the O- rings in it are something useful.
Just be aware thatís probably a real ďmetricĒ or Din 3770 kit. There quite a bit different to the JIS sections. Close enough to still cause some grief.

The Japanese J.I.S standard has 1.9, 2.4, 3.1, 3.5, & 5.7mm cross sections.

The Din ones will all be nominal or half millimeter sizes. 1, 1.5, 2, 2.5, 3, 3.5, 4 & 5mm. The I.Dís of a JIS ring will be smaller than a DIN ring.

Regards Phil.

bgott
07-11-2009, 11:03 AM
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?function=Search

It looks like it has the JIS sizes. Now that I know that I'll keep my eye out for the DIN sizes. Is that all or is there British sizes, too? We are supposed to change over to metric to standardize the world, I would feel more of an urgency to convert if there wasn't so many metric standards for the same thing. :)~

Machtool
07-12-2009, 12:16 AM
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?function=Search (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?function=Search). Is that all or is there British sizes, too?
This might come as a shock. To the best of my knowledge the American and the British are the same. The British Standard B.S 1806 is the same as the American AS568

Your link didnít work for me, so I searched them any way. Looks like they carry two metric kits, both are J.I.S 1/, ITEM 96282-3VGA $4.99 & 2/. ITEM 91512-6VGA $9.99. That second one has all the rings in it that the O.P wanted, and he would have 392 spares left over. However I think thatís a bit too cheap. I pay about $70 for a decent kit.

Maryland Metrics show a good range. http://mdmetric.com/oring1.htm (http://mdmetric.com/oring1.htm)
The first few are the DIN sizes. The ones towards the middle of the page are the JIS. That kit they have there for $32.95, almost has every thing he needs, except it has a P10A instead of a P10. An ďAĒ after the number means itís a fatter section, 2.4 instead of 1.9mm.

Cheers Phil.

bgott
07-13-2009, 12:17 AM
I'd never had call to study up on metric o- rings, when I needed them I just matched them up. Now that I'm set for oriental stuff I need to find out what I need for my New Holland TN 65, Italian built FIAT tractor.