Rebuilding a Meltrope BCN Needle Sharpner

[Lah Ca]

I have acquired a Meltrope BCN needle sharpener, which is in need of help.

The emery pad is worn out and was swollen and puffed up from exposure to humidity. I have worked Weldbond glue into the separated layers of the pad from its edges, and clamped in down with a large washer of similar size and a number of small screw clamps. This is working well at producing a flat stable pad. The emery surface is mostly worn off down to the paper. But the gluing and clamping has produced a very flat surface now.

I see pictures of these devices which have been up for sale with spare emery pads. Unfortunately mine has none. I will have to cut emery cloth to shape and glue it to the surface of the remaining pad. I could probably cut new pads out of linoleum or cork if necessary.

In the pictures, I also often see one or more emery board (like a small, short, broad fingernail board) with these machines. Mine has three or four of different grit. I do not know what these are for or if they are original to the box. Any ideas?

Here is a picture taken from an image search:

Also missing from mine is the red rubber ring that goes around the shank for the needle and protects the emery pad from contact with the metal. In some pictures, I see rings of different sizes. I will have to conjure up something to serve this purpose. I would assume that the rings of different sizes would control the bevel on the needle point.

Here is another picture taken from an image search showing the rubber ring intact.

2023-03-20 12.44.57 i164.photobucket.com 9f531320b8fc.png (388.15 KiB) Viewed 904 times

Any advice, information, suggestions, etc, would be appreciated.

Thanks.

[Orchorsol]

Great acquisition! I put these into good working condition frequently, as I sometimes sell them alongside new BCN thorn needles.

That's a thick solid cardboard ring under the emery surface (edged in red). Now that you have compressed it back into shape, use a craft knife / exacto knife or similar to cut the thin emery surface off. You can then make a replacement abrasive ring using a compass cutter (cheaply available on eBay and elsewhere). Use 240 grade wet-and-dry emery paper.

For the "tyre" I normally use a 9.2 x 2.6 mm silicone rubber o-ring, 70 Shore hardness. I'll happily send you one for the cost of postage. Very occasionally a slightly different size is needed.

I think the different grades of abrasive ring you found in the box are probably from a past owner. As you say, sometimes these are found with spare rings (sometimes already mounted on the card spacer), but I haven't seen different grades before.

[Orchorsol]

Again I've responded too soon before fully and carefully reading your post! The little things like nail files are the earlier more primitive means of sharpening thorn needles. You had to spin the needle in your fingers whilst stroking it to and fro at approximately the correct angle.

There's another type much less frequently seen which is a flat folded loop of emery paper with the abrasive surface inside - you inserted the needle, pinched the "sharpener" and turned the needle.

[Lah Ca]

@Orchorsol

Thank you for the replies.

I will post pics in a bit.

[Lah Ca]

Here is what came in the box with my sharpener.

• The sharpener with two chucks.

• Five small rectangular emery boards of different grit, four double-sided, one single-sided.

• A small fragment of wood - looks like lauan veneer.

• And finally what appears to be a gold Pathé decal/transfer.

[Lah Ca]

That's a thick solid cardboard ring under the emery surface (edged in red). Now that you have compressed it back into shape, use a craft knife / exacto knife or similar to cut the thin emery surface off. You can then make a replacement abrasive ring using a compass cutter (cheaply available on eBay and elsewhere). Use 240 grade wet-and-dry emery paper.

I am not quite finished work on stabilising the cardboard ring. It was in very bad shape initially. I may yet end up fabricating a replacement out of linoleum or cork flooring.

The only circle/compass cutter I can find in shops here is one by Fiskars, and it is a bit expensive. The Olfa ones online don't look too bad for the price, but none of the cutters offered online, including those from Olfa, have strongly positive reviews . So, I may experiment with a compass from a geometry set and a small Xacto knife in place of a pencil.

I will go shopping for emery cloth in the next few days.

For the "tyre" I normally use a 9.2 x 2.6 mm silicone rubber o-ring, 70 Shore hardness. I'll happily send you one for the cost of postage. Very occasionally a slightly different size is needed.

Thank you. I may take you up on the offer if I cannot find anything suitable here easily.

[Orchorsol]

I am not quite finished work on stabilising the cardboard ring. It was in very bad shape initially. I may yet end up fabricating a replacement out of linoleum or cork flooring.

The only circle/compass cutter I can find in shops here is one by Fiskars, and it is a bit expensive. The Olfa ones online don't look too bad for the price, but none of the cutters offered online, including those from Olfa, have strongly positive reviews . So, I may experiment with a compass from a geometry set and a small Xacto knife in place of a pencil.

If you need a good original cardboard ring, let me know, I have a few in stock - also happy to send you an abrasive ring if you need one - I use cheap compass cutters like this, a little tricky to use being rather flimsy, and I go through a lot of blades cutting through emery paper, but they work fine for me (all seem to be the same product sold under multiple brand names)
https://www.ebay.co.uk/itm/134452217328
https://www.ebay.com/itm/225482459763

[Lah Ca]

Back working on this little project after a forced absence.

Use 240 grade wet-and-dry emery paper.

I am having trouble finding this grade of emery paper. I can find lower and higher, typically 180 or 300. I don't imagine it matters that much if the grade is somewhat higher.

For the "tyre" I normally use a 9.2 x 2.6 mm silicone rubber o-ring, 70 Shore hardness. .... Very occasionally a slightly different size is needed.

Do you know the AS568A reference number for this size of o-ring? What dimensions are we discussing, outer, inner, axial?

Canada is officially a metric country but we do not seem to function well entirely in metric.

Thanks.

[Lah Ca]

Done ... well ... at least for the first go round.

I ended up having to treat the surface of the cardboard ring with a cellulose filler to get the ruts out of it. I then finished it flat.

I found an envelope with about 30 sheets of 8" by 12" self-adhesive wet-dry emery paper in a box of stuff in my garage. It is too fine for the purpose at hand but it works well enough. I did a free hand circle cut through the back of the paper after tracing the disk on to it. It came out only a little more ragged than a compass cut might have, but then the cardboard ring is slightly out of round now, and I would have had to trim the emery paper anyway.

I gave up trying to find o-rings in the shops and just took the sharpener to my mechanic and hit him up for a couple of trial-and-error-fitted o-rings that seem to work OK.

I tested it with five used cactus needles I have had kicking around, waiting for a sharpener. It works very well but probably a little slower than with a coarser emery paper.

I examined the needles with my jeweller's loupe and decided to do a cork polish on them to remove the sanding dust.

[Orchorsol]

Well done!

In answer to your previous questions 9.2mm is the o.d., 2.6mm is the thickness. But maybe 25% of these sharpeners (and a much higher proportion of IM Pointmasters) need trial-and-error to select the right size, as you have found. A lower hardness value would help accommodate, but not always easy to find since most normal applications for o-rings are for sealing.

240 grade emery makes a big difference.