Bad Idea?

[Texian]

The following got no response on another forum, and am curious what you all think. Some folks use a card scraper (flexible handheld furniture scraper) to smooth/level the O.D. of turnings, as this can be easier than sanding away those little hills and valleys. Wanting to try this without buying anything, I passed the back edge of an old hacksaw blade across the fine grinding wheel to raise a burr. Being quite flexible the curvature can be varied to suit the work, and it will scrape or shear scrape as desired. It works a treat, as we say in Texas. Leaves a surface ready for 180 or finer sanding, depending on the wood. Granted there is some potential for injury if it should somehow catch and be torn from one's hands. Maybe some small handles or grippers attached to both ends of the blade would be good. Have only tried this on a couple of segmented pieces, so I was scraping parallel to the grain at all times. Not sure how well it would work on cross grain. What do you think?

[Ad de Crom]

Richard, this is not a bad idea.
Used many time a multifacenet scraper for outside smoothing, but sanding afterall is always needed.
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[robo hippy]

I have tried a card scraper a few times, and it works better with the lathe off, or running very slow. I did find out that the burr on your scrapers at a shear angle (45 or more degrees) works as well or better, is easier to hold, you can use it at higher speeds, and it has a nice long handle on it. I generally use the burr straight from my grinder, but a burnished burr will work a bit better.

robo hippy

[artme]

Very interesting Richard. Must try.

[munruben]

Sounds okay but will wait for someone else to try it out first.:)

[NeilS]

Good or bad, it's standard practice in Japanese woodturning.

They use exactly what you have, wide blades, and have a waterstone next to the lathe and frequently swipe the blade on the stone to maintain the burr without leaving the lathe.

A wider blade provides more grip. Just grind off the teeth to save your fingers in case it should slip from your grip.

Less dangerous than lots of things we turners do, just wear your eye/face protection as we all should do as standard practice.

Old bandsaw blades would also be worth a go.

Hmm... have an old 30mm blade I must try...:)

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[Texian]

Thanks everyone for your support. I appreciate it. Best (?) feature of the hacksaw blade is the ability to hold it in a curved/bent position to smooth the curvature of the work, eliminating humps and flat spots. Can even be used (carefully) on some of the interior of larger bowls. Works fine on end grain turnings also, but have not tried on face grain turning yet.

[hughie]

Richard I have one, what more can I say. :U

Some folks just don't like thinking outside the square

I use an cold saw blade ground with various curves

[Eldanos of KDM]

Good idea....
It'd be easier and safer if you could make the piece of work turn away for you.

[rsser]

One of our turning demonstrators, Guilio M, showed this technique inside a deepish straightish sided form at a WWW show a few years back. Conventional cabinet scraper.

[tea lady]

One of our turning demonstrators, Guilio M, showed this technique inside a deepish straightish sided form at a WWW show a few years back. Conventional cabinet scraper.:2tsup:A bit more to hold on to in one of those too.

And I watched Vic Wood do it with a normal turning scraper last week. :cool: No flex of course.

[RETIRED]

:2tsup:A bit more to hold on to in one of those too.

And I watched Vic Wood do it with a normal turning scraper last week. :cool: No flex of course.Ahem,
I showed you also.

[NeilS]

Good idea....
It'd be easier and safer if you could make the piece of work turn away for you.

Yep, half the piece turns towards you the other half away from you, regardless of the rotation.

Just get the toolrest out of the way, it's not needed, and is a potential safety trap.

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[tea lady]

Ahem,
I showed you also.:D Yes! With one of those kidney shaped cabinet scrapers. :cool:


Yep, half the piece turns towards you the other half away from you, regardless of the rotation.

Just get the toolrest out of the way, it's not needed, and is a potential safety trap.

.....Yes! No tools rest.

Here is the pic of Vic. :U

Notice - NO tool rest. Fingers up close to the tool tip supporting the scraper held at a kind of angle to the bowl. Lathe turning in the normal way, tool on the bottom half of work. I think the handle is held on the body so it doesn't waggle around in teh air all over the shop. Super sharp tool.

130840

[turnerted]

Bruce Leadbetter sells a scrapper designed for this purpose . It's sort of kidney shapped with a bigger radious at one end than the other . Cost $10 I think . I bought one years ago , used it a bit then forgot about it . Now you have reminded me I should try it again since my turning ability has improved considerably since then .

Ted

[NeilS]

Worth noting that the steels in band and hack saw blades, and cabinet scrapers, are made of standard carbon steel, not HSS. Standard or high carbon steels can produce very fine sharp edges, but this sharp edge won't last anywhere near as long as a HSS edge. That's why the Japanese turners keep their waterstones on their lathe beds/benches so they can frequently refresh their scraper edges without leaving the lathe.

Using HSS scrapers the way Vic does (and yours truly) reduces the frequency of sharpening required, but the disadvantage is that HSS is not thin and flexible, like the high carbon scrapers and blades, and won't follow the form the way Texian has described.

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[tea lady]

The long awaited "Sheer scraping tutorial" is not far off, so you may not need to do it this way soon. :cool::D Although I guess there is always the recalcitrant piece of wood that demands the unorthodox approach.:rolleyes:

[NeilS]

Although I guess there is always the recalcitrant piece of wood



.or recalcitrant turner...:U

.....

[Texian]

It's true that the old hacksaw blade does not hold a good scraping edge for long, but one is only making a few light cuts on a piece to smooth the curvature so it's not a problem. My last cut(s) on a piece (before "hacksawing" if needed) are always shear scrapes with the bowl gouge. As mentioned in the other thread, shear scraping anywhere near the nose of the bowl gouge can leave ridges (hills and valleys), especially if your tool control is imperfect like mine. The hacksaw blade smooths/levels these irregularities.

Seems like a small, kidney shaped scraper would be great for the inside of bowls. May have something in my junk pile to make one of these.

[rsser]

For removing small ridges in soft or med density woods they may have a role. For leveling down to groove bottoms I'd reach for a real scraper.

On harder woods I can't see the burr lasting long.

[Texian]

But Ern, your tool control is better than mine. With a real scraper I would still have a few hills and valleys. By hills and valleys I mean stuff to maybe .005" (.13 mm) total variation that may not be obvious to the eye from a short distance, but can easily be felt by the fingers.

Agreed the burr would certainly not last long on some of your hard Aussie woods.

[rsser]

5 thou? ... power sanding wld be quicker than scraping doncha reckon?

[Texian]

It is on little pieces. Maybe those flat spots on larger pieces are bigger/deeper than I thought. Seems to help get smooth curvature with no palpable irregularities.

[colhu]

For what its worth, I made a couple of scrapers out of an old handsaw blade a few years ago after we saw them demonstrated at a Guild meeting - one with straight edges and corners just under and just over 90 degrees, and one with various curves. I'm guessing it was reasonable quality carbon steel. They seemed to work well if you kept the edges burnished, but I didn't persist with them.

cheers, Colin

[idahohay]

I use a number of curved scrapers from my past life as a luthier. Used Japanese pull saw blades, and taping knife blades work well. The thin scrapers are often ground with a 45 deg. edge then lightly burnished (something like one light pass with a burnisher) Thicker less flexible blades are sharpened square edge.

In a lathe situation the edge will only last for a few seconds. The last time I used one was on the wings of a natural edge bowl turned wet, out on the wing tips where a few tool marks remained.

[Texian]

Note that the trusty hacksaw blade is held in a concave curve for smoothing the O.D. of a piece. More interesting thread than inticipated.