Scraper staying sharp..

[FrikkinDust]

First of all, hello! Been lurking for years and finally joined up.

I have a question regarding my scraper. I'm attempting to scrape off the varnish finish from an old table as it's scratched (I will later re finish it) but my scraper stays sharp for about 3-4 strokes then it's useless. Am I doing something wrong with sharpening it do you think? Could the burr be too big? Or too small? or is the varnish too hard for it?

Thanks a lot.

 

[Jacob]

I'd use Nitromors or it's new equivalent. Quicker easier and more effective.

 

[carlb40]

You could get something like this
http://www.ebay.co.uk/itm/Bahco-665-Car ... 2ead7ce10b

I have one and it's a great tool. Easier to use on big areas. Uses replaceable carbide blades which stay sharp for ages. Plus it will be a lot less messy with no need for neautralising strippers afterwards

 

[Ian down london way]

Are you just taking off varnish, or wood too.

I've found that the trouble with scrapers like the one shown above, is if they dig in at the edges - a problem with any scrapper that is straight. If the scrapper has a slight curve (which obviously cabinet scrapers do) then the edges don't dig.

I do wonder if what you are seing is simply the vanish clogging the bur, rather than the bur, um, deburring.

If its a proper scrapper (metal hardness-wise), there is no way it should be lasting for so short a time.
Mind you, if its been flattened using a power tool, which may have heated the edge, then metal will loose its strenght. Still, I expect you are suffering from clogging.

Try some white spirit and wipe the scrapping edge.

 

[mickthetree]

On naked wood a scraper will last a goodly while before it needs re-sharpening, but on old hard varnish it might be a bit too much for the edge.

I normally use a medium scraper on naked wood, but keep a thick scraper for heavy duty work such as this. Maybe try a thicker one?

HTH

 

[Paul Chapman]

my scraper stays sharp for about 3-4 strokes then it's useless. Am I doing something wrong with sharpening it do you think? Could the burr be too big? Or too small?

It should stay sharp far longer than that. You don't say what type of scraper it is or how you are sharpening it and turning the burr. Too big a burr will be weak and tend to break off.

Cheers :wink:

Paul

 

[FrikkinDust]

Thanks for the replies.

Carl - Good call, might be worth a go but I try a few other things before I start spending money
Ian - I'll try cleaning it with some white spirit, maybe it is getting clogged.

And maybe it is a bit of a pansy scraper. It's a marples one from the Bay (although it doesn't have marples anywhere on it).

 

[Muswell]

This will sound like heresy but try filing a 45 degree edge on your scraper and don't worry about all that burnisher stuff. That's what I learnt to use for scraping serious amounts of wood shaping a violin, and it stays sharp. Seems to work on some varnish I just tried it on. You might need to finish off with the more usual edge once the varnish has gone

 

[No skills]

Thats interesting, do you sharpen/smooth the 45 degree edge on a stone after you file it or just file it and straight to work?

 

[Muswell]

I just file it with a smooth cut for rough work. For a bit more finesse I run it over an oil stone. I have just bought a single cut "farmer's own" file from Axminster and that gives a better edge.

 

[No skills]

Cheers, something to try out.

 

[FrikkinDust]

This will sound like heresy but try filing a 45 degree edge on your scraper and don't worry about all that burnisher stuff. That's what I learnt to use for scraping serious amounts of wood shaping a violin, and it stays sharp. Seems to work on some varnish I just tried it on. You might need to finish off with the more usual edge once the varnish has gone

Interesting...., cheers bud.

 

[hanser]

http://www.screwfix.com/p/harris-heavy- ... 1001628529

I use this for scraping varnish. paint etc on my boat. Used it a fair bit last season and still the same blade. Not so hefty/expensive as the Bahco.

 

[brihol]

Coincidentally scraper sharpening was in the last blog from Matthias Wandel at Woodgears
http://woodgears.ca/scraper/index.html#v

Brian

 

[Eric The Viking]

Having a bevel seems to work with thicker scrapers. I bought a secondhand Record scraper - I think it's #80 - and that had a chunky bevel on it, at 45deg IIRC.

I polished the back and sharpened it like an ordinary plane iron (with a slight curve, too) and it seems to cut well without needing an edge turned as well.

I'm probably not doing it right...

 

[Sgian Dubh]

I have a question regarding my scraper. I'm attempting to scrape off the varnish finish from an old table as it's scratched (I will later re finish it) but my scraper stays sharp for about 3-4 strokes then it's useless.

Like Jacob said, you'll be better of using a paint stripper to remove old varnish. Nitromors is a well known brand, and although the formula was changed a couple of years ago to comply with a European Union directive on health issues, it will do a better job than a scraper in about 95%+ of cases. If done correctly with a paint stripper all you'll need to do afterwards is apply a new finish, almost certainly with no additional planing, scraping or sanding. This way at least you retain the original patina and colour of the underlying wood, whether it was varnished natural or if it was varnished after some other process such as dying, and/or staining, and/or grain filling.

On the other hand if your intention is to get down beyond the original finish to bare wood and then refinish, then I'd still use a Nitromors type stripper to get the old varnish off, then plane and/or scrape and resand to prep the wood prior to applying your new finish.

If you've already scraped to the point that you've revealed bare wood in at least some places then you have no choice but to get the whole thing to the same state, and all of the above suggestions are moot.

You may not be sharpening your scraper either incorrectly or correctly: I can't tell that from your initial question, and using even a well prepared scraper on varnish is generally a frustrating task as you've found because of the tendency to clog up. You've received plenty of suggestions for scraper sharpening, some helpful and some less so, so I'll leave that topic for others. Slainte.

 

[Jacob]

If you use Nitromors etc shavings or sawdust is useful to clean it off. Scatter it all over and rub it in, scrub it about, by hand (with gloves on - those red rubbery ones which aren't actually rubber). Then brush it in/off. Stiff plastic brush. Old toothbrush for the tight corners.

 

[GazPal]

Crud build up on old finishes often knocks heck out of sharpened edges, so I'd not worry too much over your sharpening technique. Edge quality and durability will improve with more sharpening practise and you'll soon get the hang of it, but I'd definitely recommend using Nitromors to strip old varnish rather than scraping and the risk of damage to the underlying surface.

Tip: Round over the corners on scraper blades if you wish to avoid them digging into the surface you're working on.

 

[FrikkinDust]

Thanks all. I'll try cleaning the edge, if no dice I'll try nitromors, then hit it with a belt sander to get back to new wood. I'll report back...