Burnisher or screwdriver?

[David C]

Polished carbide, or was it powder metal, works very well indeed.

Just don't ask how I know !

David Charlesworth

 

[Tony Zaffuto]

Polished carbide, or was it powder metal, works very well indeed.

Just don't ask how I know !

David Charlesworth

Highly polished carbide and not powdered metal David!

None of the commercial carbide products (from woodworking vendors) have that degree of polish nor do they have the inherent lubricity of that specific grade/type of carbide. Unfortunately I no longer use that type of carbide in my manufacturing plant, but one of these days (when I have some spare time), I may order some carbide of that grade and make a run of burnishers.

In lieu of that grade of carbide, any M2 or HSS drill rod, which will mirror polish far easier and used with a light swipe of camellia or a mineral oil, will do as good a job.

 

[Graham Orm]

Polished carbide, or was it powder metal, works very well indeed.

Just don't ask how I know !

David Charlesworth

Powder metal?

 

[David C]

Can't remember, but is carbide not a form of powder metalurgy. i.e. where the constituent parts start as powder and are then compressed under high pressure and temperature to form the metal?

PMV-11 is a good example. Good description of the process on axminster site.

David

 

[Graham Orm]

Ah, thanks David, I've ordered the ARNO.

 

[Cheshirechappie]

Just in case anybody is still following this thread, here are some comparitive hardness figures.

Spring steel used for scrapers will be about Rc40-52 depending on grade and degree of temper. A 0.8% straight carbon steel (Disston used this for their sawblades, according to the Disstonian Institute website) will be at the lower end of this range, and 0.95% carbon steel (which probably brackets a lot of 'cast steel', as well as the much vaunted '1095' grade, the American equivalent of the British CS95, very similar to En44) towards the upper end of this range. Most card scrapers are likely to be nearer the lower end, with just the 'premium' ones at the higher.

Chisels and gouges of O1 steel, and the old 'cast steel', are hardened and tempered (the tempering to improve toughness slightly at the expense of hardness) to about Rc62, though there will be some variation. So most gouges will turn a burr on most scrapers.

A piece of silver steel (North America - 'drill rod') which is a very similar chemical composition to 'cast steel', can be hardened 'right out' to Rc69, though it would be wise to temper it back a little to release some of the hardening stresses (boil in water for an hour or so), and will end up somewhere around Rc 67. The chrome plating on a screwdriver shank will be about the same hardness, so both of these will make acceptable burnishers.

Tungsten carbide (which is manufactured as a powder, and made into useful form by moulding under heat and pressure) achieves hardnesses in the range Rc 70 and above, so will make an almost 'overkill' burnisher.

Overall conclusion - the 'posh' carbide burnishers will do a fine job, but if the budget doesn't stretch that far, a chrome-plated screwdriver shank or a gouge back will almost certainly do a very acceptable job - and years of experience would seem to bear this out.

 

[Tony Zaffuto]

Can't remember, but is carbide not a form of powder metalurgy. i.e. where the constituent parts start as powder and are then compressed under high pressure and temperature to form the metal?

PMV-11 is a good example. Good description of the process on axminster site.

David

A form but the processing is far different from conventional powder metal. Conventional powder metallurgy has an inherent porosity of around 14% voids among metal particles, whereas carbide approaches full density and nearly the same as traditional wrought materials. PMV-11 is proprietary to LV, though I have my ideas about how it is processed.

Conventional PM parts will break, leaving an interior looking like very fine grained casting. Carbide, if dropped will break also.

If anyone wants to learn more about powder metallurgy, our trade group's website is "Metal Powder Industry Federation" (MPIF). I am a member as a parts producer, primarily for the automotive industry.

 

[Tony Zaffuto]

Overall conclusion - the 'posh' carbide burnishers will do a fine job, but if the budget doesn't stretch that far, a chrome-plated screwdriver shank or a gouge back will almost certainly do a very acceptable job - and years of experience would seem to bear this out.

Carbide will out perform any other material, however, it must have almost a mirror finish to do that. Without that fine of a surface finish, the results may be poorer than the typical burnishing methods (screwdriver, etc.).

A drawback of the "posh" carbide is that if dropped, there is a high degree of certainty that the burnisher may break, where traditional wrought materials will not.

 

[MIGNAL]

Couple of quid. Free if you know a mechanic.
Works perfectly well. As good as anything out there. . . but why wouldn't it?

 

[Derek Cohen (Perth Oz)]

Someone once suggested I try a pinion gear. Well I did have one lying around. It didn't work out well, however ...

Since then I have relied on a burnisher made with a polished carbide rod that Tony Z gave me. Here it is with the Crown burnisher for size.

Thanks again Tony.

Regards from Perth

Derek

 

[bugbear]

Overall conclusion - the 'posh' carbide burnishers will do a fine job, but if the budget doesn't stretch that far, a chrome-plated screwdriver shank or a gouge back will almost certainly do a very acceptable job - and years of experience would seem to bear this out.

Carbide will out perform any other material, however, it must have almost a mirror finish to do that. Without that fine of a surface finish, the results may be poorer than the typical burnishing methods (screwdriver, etc.).

A drawback of the "posh" carbide is that if dropped, there is a high degree of certainty that the burnisher may break, where traditional wrought materials will not.

Thanks for the info - might I assume that polishing carbide (shoudl the piece you have be unshiny) is an "interesting" excercise?

BugBear

 

[Tony Zaffuto]

Overall conclusion - the 'posh' carbide burnishers will do a fine job, but if the budget doesn't stretch that far, a chrome-plated screwdriver shank or a gouge back will almost certainly do a very acceptable job - and years of experience would seem to bear this out.

Carbide will out perform any other material, however, it must have almost a mirror finish to do that. Without that fine of a surface finish, the results may be poorer than the typical burnishing methods (screwdriver, etc.).

A drawback of the "posh" carbide is that if dropped, there is a high degree of certainty that the burnisher may break, where traditional wrought materials will not.

Thanks for the info - might I assume that polishing carbide (shoudl the piece you have be unshiny) is an "interesting" excercise?

BugBear

Pretty much an exercise in futility, unless you do it in a powered lathe, with progressively finer grades of diamond compound, with proper breathing apparatus (grinding carbide is toxic) and a great deal of patience!

In my manufacturing plant maybe a half dozen years ago, the type of tooling we utilized had core pins made of carbide. Stuff would never wear out and at the conclusion of the part run, I ended up with specially sized pins that could not be easily or cost effectively modified for other part runs. A light bulb went off while honing a scraper, to try a piece of carbide as a burnisher and it worked beautifully.

I'm a member of the "Old Tool List" and in a discussion about burnishing, I mentioned the use of carbide and received some emails about where to get some. I posted that if anyone wanted a piece, I would mail one at no charge. To make a not so long story short, I sent pieces all over the world, made a lot of friends with some so appreciative, that they mailed back to me a gift (I'm still using the marking knife Derek!).

Since then we have moved to less expensive (but equal to the task) M2 drill rod.

 

[Racers]

Yes I remember that on the Old tools list.

Its one reason I made mine, it was nagging away in the back of my mind for a while.

Pete

 

[bugbear]

Yes I remember that on the Old tools list.

The most knowledgeable, civilised, polite discussion forum I know of, no exceptions.

BugBear

 

[Graham Orm]

My ARNO burnisher arrived this morning from Workshop Heaven. Does it make much difference? Is it any better than the screwdrivers etc that I've been using?
http://www.workshopheaven.com/cgi-bin/s ... tml#SID=44

You bet it is. Instant result, lovely curly shavings. Very pleased and impressed........now where's that gnarly beech???

It was the video that sold it Matthew. :wink:

 

[Trafalgar]

My ARNO burnisher arrived this morning from Workshop Heaven. Does it make much difference? Is it any better than the screwdrivers etc that I've been using?
http://www.workshopheaven.com/cgi-bin/s ... tml#SID=44

You bet it is. Instant result, lovely curly shavings. Very pleased and impressed........now where's that gnarly beech???

It was the video that sold it Matthew. :wink:

Scraping? Tisk, tisk. Didn't you know that you should be able to finish right off the plane on every species at all times and in all places?

:lol:

I'm like the late John Brown. If the shop were on fire (with me in it) my set of scrapers would be the first thing I grabbed.

 

[Graham Orm]

My ARNO burnisher arrived this morning from Workshop Heaven. Does it make much difference? Is it any better than the screwdrivers etc that I've been using?
http://www.workshopheaven.com/cgi-bin/s ... tml#SID=44

You bet it is. Instant result, lovely curly shavings. Very pleased and impressed........now where's that gnarly beech???

It was the video that sold it Matthew. :wink:

Scraping? Tisk, tisk. Didn't you know that you should be able to finish right of the plane on every species at all times and in all places?

:lol:

I'm like the late John Brown. If the shop were on fire (with me in it) my set of scrapers would be the first thing I grabbed.

I've had a traumatic experience (noted in another thread) with some rampant beech that simply wouldn't plane without tearout......ok, it might have been me.....but I very much doubt it.

 

[David C]

I like to maintain that any hardwood can be planed with suitable technique.

Some of the very obstinate ones can be a little furry, but light sanding sorts this out.

David Charlesworth

 

[Racers]

Yes I agree, but us mere mortals without a Charlesworth super smoother have to result to a card scraper every once and then.

:wink:

Pete

 

[Graham Orm]

I like to maintain that any hardwood can be planed with suitable technique.

Some of the very obstinate ones can be a little furry, but light sanding sorts this out.

David Charlesworth

I've just had great success with my newly sharpened scraper, which will be followed with sanding. Thanks for the input.