Making a better felt filter for the oil tank

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Re: Making a better felt filter for the oil tank

Postby REW » Sat Mar 02, 2019 1:31 pm

Work of art, Alan, work of art. Mrs GL is to be commended too.

What is the finished length, btw?
Ron

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Re: Making a better felt filter for the oil tank

Postby Group Leader » Sat Mar 02, 2019 8:12 pm

Thanks Ron, I'll pass on your kind comments on to the management. :)

172mm IIRC - I don't know what the tolerance should be but hopefully the felt will squash up a bit to soak up those two pesky mm!
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Re: Making a better felt filter for the oil tank

Postby Rob Harknett » Sun Mar 03, 2019 12:08 am

Group Leader wrote:And this evening I have been sewing ... and then my wife took pity on me. She's far better at sewing then me!

I tried the overlapped joint approach but, try as I might with straight or bent needles I didn't get very far (about 3"). So, just as an experiment Mrs GL finished the job by butting the edges together and sewing across the seam.

The net result? A re-felted filter that looks like it's just the job, with the right OD over the felt ends and maybe a mm or two a bit too long. I feel a second go at the felt is required; without the interesting transition between styles half way along! I'll use either the butt joint or maybe have a go at the most easily sewn, external seam although I can't help feeling that will end up with too much spare material.

Anyway, I think I'm on the Home Straight with it now and I think you'll agree, it seems perfectly "doable" - I'll just have to wait for a 1000 miles or so until the next oil change to see if it fits and works!

Alan
There is more open space in the wire mesh than in the perforated sheet metal, with holes that could get blocked more easily. I would not trust man made fibres that could soften, become sticky and glue up. If you do leave a sample soaked in oil to check. Occasionally drop dirty waste oil on it to check it still filters through OK. It will give you clues as to the filter working OK.

Eh voila.jpg

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Re: Making a better felt filter for the oil tank

Postby Group Leader » Sun Mar 03, 2019 9:09 am

Rob Harknett wrote:There is more open space in the wire mesh than in the perforated sheet metal, with holes that could get blocked more easily.


I agree Rob. I did have a sniff around some of the perforated sheet tube suppliers but couln't find any of the correct diameter and also thought there was generally too much "Polo" and not enough "Hole". Sticking with the mesh is the way to go in this case I think.

Rob Harknett wrote:I would not trust man made fibres that could soften, become sticky and glue up.


Which is why we plumped for the 100% wool felt material on the assumption it was sheep-made not man-made .....

Felt Info.jpg


..... that assumption could be wrong of course.

Just to be sure though, I have a sample soaking in some previously enjoyed "Classic 20/50" as we speak. It can stay there until the next oil change is due :)

Alan
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Re: Making a better felt filter for the oil tank

Postby Rob Harknett » Sun Mar 03, 2019 10:39 am

Even gen lambs wool would need to be manufactured using the same quality, weave etc. suitable for the job it is intended for. I am not so sure cloth type felt from a drapery shop would be of the standard required. Having used lambs wool felt in the wood working trade as a tool, I have experienced variations. The felt used was 1/2 " thick. First test was, how hard and compressed was it? If poked with a finger and you were able to compress it even slightly. You knew it was not going to be much good, as it would have to take a lot of friction, when depressed on a fast moving, machine belt sander. It would also need to stay flat and smooth, to give the required finish on the material being sanded. So one should expect, certain requirements would have to be met, for a lambs wool product, to be used for filters, oil seals etc. I would at least try a pinch test. If you can pinch it wafer thin, oil will probably pour through it. Not filter its way through, trapping the muck. So on filling with fresh oil, note how quickly the oil goes black. To see how good the felt used is filtering the oil. The actual filter would also need to be a good fit it the tank, to insure all the oil goes through it. I have come across filters a little bent. Perhaps they bent, as the more rigid joint side, bowed over time, the more flexible opposite side allowing it to do so.

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Re: Making a better felt filter for the oil tank

Postby REW » Sun Mar 03, 2019 12:28 pm

To be sure a piece of felt is natural and does not contain artificial fibres, put a match to it :twisted:

The difference is obvious...

As for the fit, just use an "O" ring at the base, if needed, to take up any vertical slack.

Quality of felt, well yes, but the stuff Alan has used is pretty good in hand as I too know. Vastly better than the stuff in the currently available pattern filters.
Ron

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Re: Making a better felt filter for the oil tank

Postby Group Leader » Wed Mar 20, 2019 10:42 pm

After a 3 week soaking in old oil followed by a really good squeeze the felt seems to be standing up nicely with no apparent tendancy to disintegrate which is encouraging.

Filter Felt.JPG

Hardly a scientific test I realise, but I think I'm happy with that.

Alan
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Re: Making a better felt filter for the oil tank

Postby Group Leader » Fri Jun 21, 2019 8:50 pm

Well it was finally time for an oil change and the first use of my new filter.

It seems that ideally, the filter could be a couple of millimeters shorter and one , maybe two, millimeters smaller diameter on the end rings than I have made. Consequently it was a tad tight in the filter chamber but went in OK with a little assistance and seems to be functioning correctly with oil passing satisfactorily back into the tank. Because I'd completely drained the tank and the filter chamber it took a while for the oil flow to become visible out of the return into the tank pipe (that's normal of course) but whilst waiting for it to appear I realised it obviously has to re-fill the filter chamber first.

The obvious trick here then is to fill the chamber with oil after inserting the filler prior to replacing the washer/spring/cap combination! Next time .....

Alan
1953 AJS 16MS, 1939 BSA 250 and a 1/3 scale Sopwith Triplane but that's another story ..... :lol:

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