Helical pencil sharpener blade replacement

I was tasked to repair a helical pencil sharpener which had some sentimental value hence looking for suitable spares. The model is a Boston 200, made my Gillett and sons and it looks as though the blade is dull as its hard to crank.

As far as I am aware these sharpeners are no longer made but there are other similar designs made by different companies and spare cutters.

Does anyone know of a suitable replacement helical blade, even if I have to canabolise another replacement system to fit?

Measurements of the cutter are 15.05mm x 38.75mm with an 11 tooth gear and 15 helical cutting flutes.

Edited By jon hill 3 on 14/03/2021 21:13:31

Good luck with that. You might be better off to sharpen the cutting edges with a small diamond file.Or a Dremel tool if you have a steady hand.

Edited By Hopper on 14/03/2021 21:14:58

Yep bit of a long shot, however I am sure some company is still using the same spec cutter.

I know most retailers/suppliers wont reply if I ask the dementions of their replacement cutters...

May not be that hard to sharpen actually. I would work on the flutes rather than the outsides of the cutting edges. That gives you a very defined face to work against. See how you get on with a diamond file first and if it really is too slow then think about a small wheel.

regards Martin

2 Questions How hard is it to crank without a pencil in place? Gear looks messy, have you tried a little lubrication?

It may be worth contacting Jackson’s ... They seem to know more than most:

**LINK**

https://www.jacksonsart.com/blog/2020/03/23/comparing-manual-electric-pencil-sharpeners/

MichaelG.

Looks like a job for a VERY good man and a clarkson air bearing flute grinder ! Noel

Jakar - well know auction site spares listed. Caran d' Ache helical cutter replacement on Amazon UK (should I have mentioned this) Google make of machine as above and add spare parts. I obviously don't know if they will fit but with the sentimental attachment worth a punt and may be capable of modification to fit.

Robert Butler

There's a couple of candidates on eBay at the moment
One Boston and one Gillott, in the UK as well as a spare pair of blades in the US
The US one gives a length

Bill

This type of sharpener shown by the OP was made by Boston in the US but are now or were made in China under different brands. The internals of the inexpensive x-acto one at the Canadian retailer's link below would probably be a very close match to the cutters./ gears of the one in the OP's picture. Compared to the Caran d' Ache things at 10X the price, the x-acto one might be worth a punt.

https://www.staples.ca/products/10938-en-x-acto-ks-pencil-sharpener?variant=19666712133701

Can you turn the cutters end for end - may make a difference ?

Never ceases to amaze/amuse mass variation of postal charges on items from t'other side of t'pond.

Regards Ian.

I know little of these things so forgive me if this is rubbish

If it is not cutting it is because the corner of the top to the vertical cutting edge has rounded- i would think that is stating the b..g obvious. But thinking it through & how it works, I would think that because the cutter sits at an angle the tip of the pencil does not actually reach the end of the cutter.

Therefore, instead of trying to grind the flutes why not put the cutter in the lathe & reduce the outside circumference by a thou. That should take the rounded corner off & leave a square, sharp edge. If done on the correct rotation it may leave a tiny burr but that would not be such a bad thing as it would be in the correct direction. It could be filed off.

With a smaller diameter the pencil will just go further into the unit. Hence, my comment above about how far the pencil goes in

The reduction could be done by rotating against a file or a stone perhaps. Others will know how.

If the reduction in diameter was an issue the mounting could be packed down by a suitable amount

Edited By Sam Longley 1 on 15/03/2021 08:59:55

Just measured mine, a Swordfish Curve for which this is the replacement blade, and the dimensions are:

cutter diameter 14mm

cutter length inc gear 38mm

cutter length exc gear 33 mm

10 tooth gear

axle diameter 5mm

I may have made a mistake in counting the gear teeth, and the measurements may not be absolutely precise, but it seems pretty close apart from the cutter diameter. At the price quoted, I'd be tempted to try it (other suppliers may be available, I just searched "Swordfish 40807" ). Possibly one of their other models may be a closer match. Their Customer Service department is here, or the postal address is:

Snopake Limited
Perivale Park
Horsenden Lane South
Perivale
Middlesex UB6 7RJ

Hope this helps.

Rob

Edited to remove smiley face

Edited By Grindstone Cowboy on 15/03/2021 09:25:06

To have lasted this long it will be hard and to do any job worth the name will need a grinding machine. The cutter will have a cutting edge and a clearence . It will require considerable skill to regrind, be sharp and work. One could try to do it ones self on a lathe BUT it could also be ruined. The reduction on diameter would be of the order of a few thou - nothing in this context. This item is a small milling cutter in all but name - To sharpen a milling cutter requires a tool and cutter grinder, and the tooling to hold it - this is just the same !

If a spare can be had, good. If not you may turn a poor tool into a useless one by trying. VERY careful use of a diamond file might work. Good luck. Noel.

Thanks for all the posts everyone, this is probably the most helpful site on the web.

As I no nothing about grinding helilical cutters, I think I will go for a new for old blade swap out. I does cut and still makes a nice point, however it needs to be cranked with quite a force and very tightly clamped to a suitable base. I am sure with a new cutter the current 2 handed job would be an easy one handed task.

I used to work for the Cumberland Pencil company and have seen a few of these in my time.

I have to admit I have not sharpened any. However the Boston sharpener you have the silver disc with the holes in "should " be spring loaded, The grippers at the top edge are pinched open and the pencil fed in to JUST touch the cutter let go of the grips and then crank the handle.

I am not accusing you of doing this but a lot of people are too impatient and push the pencil in hard by hand which overloads the cutter making it hard to crank.

The cutter should be making a fine planing cut as it rotates / slides past the stationary pencil.

Has the sharpener seen it lot of use, particularly on graphite ? If so then it is probably blunt. graphite leads are all fired in a furnace so you are in effect cutting rock. its just that 9B is a soft rock and 9H a very hard rock.

We always used to tell people to buy cheap hand sharpeners frequently and as soon as you start getting splinters, instead of a nice apple peel ribbon, throw it out its blunt.

Quality Pencils are far more expensive than a hand sharpener. After all you don't cut steak with a butter knife.

I hope you get it fixed. it should sharpen though as the carrier it sits in is just that, a carrier to hold the pencil in place. It does not form any part of the cutting action.

sorry if I have tought you to suck eggs.

Good Luck Clive

Don't think it'll ever be a one-handed operation - they are usually clamped to the edge of a desk, or screwed to a wall.

Rob

I have sharpened one successfully using my Harold Hall grinding set. Mine is a very old chrome job on its own stand. A small diameter grinding wheel is essential to achieve a clearance with the following cutting edge. I cannot imagine anyone achieving a reasonable result freehand as the cutting edges are so close together.

Dennis