Help needed please - new to turning!

[Soylent1]

First of all hello to everyone, and thank you in advance as this is my first ever post on here!
(although I have been reading peoples posts on here for a while)

My better half bought me an unhandled 1 1/4'' square nosed scraper for Christmas, I turned a handle (my second serious piece of turning) and mounted it over the Christmas period, I can't however seem to get this mysterious burr on the edge. I have kept the same angle as it was from the packet and flattened the top. I use a belt sander held in a vice at 90 degrees and have mounted a tool rest thingy at the correct angle. I have a bit of green oak on the lathe which I have been using to test the sharpness and grinds of my tools but no matter how much I try to sharpen the square scraper it just seems dull and vibrates when I try it.

any advice will be much appreciated and I will put some pictures of it on here ( when I figure out how to get from my phone onto the computer).

Regards Tony

 

[Phil Pascoe]

There's probably not much wrong with your scraper - you should be using a gouge on green oak. Many people go from one end of the year to the next without using a scraper.

 

[Spindle]

Hi

Green wood is not the most responsive to scraping - I'd suggest you find a piece of seasoned wood in order to assess the cut of your scraper.

An 1 1/4" square scraper is rather large and not the easiest tool to sharpen - inconsistent sharpening across it's width will result in the tool having more tendancy to vibrate due to the large area in contact with the work. I grind all of my square scrapers with a barely perceptible round nose, this reduces the area in contact with the work and subsequent tendancy to vibrate.

Once you have ground your scraper do not flatten the top, it's not necessary and will remove any burr that has formed.

Are you using the scraper in the trail mode and cutting on or just below centre line, (for external turning)?

Regards Mick

 

[Soylent1]

Thank you for your replies,

I'm just using it trailing I think, sort of underneath with the tool rest above centre and the scraper pointing downwards. I'm only using the oak as to test the tools its not a project or anything. The thing that's annoying me is I keep reading that there should be a burr you can feel with your finger after sharpening but I cant feel anything, I can feel a burr when I sharpen my roughing gouge. I read somewhere that you can use a burnish to get a burr?

Tony

 

[woodfarmer]

Spindles advice is excellent.
I can add a bit though from a past life maintaining all the machinery in a tannery.

If you put your scraper in a vice Ideally with soft jaws sharp side up and cutting edge away from you. then make as if you are filing the edge with a hard round bar (Back of gouge) Start the stroke near one edge and slide across and off the other, alternating ends. ALL the stroking (called boning) is done from the bottom of the heel towards the tip of the cutting edge. Do not go over 90 degrees, just a bit steeper than your cutting angle of the bevel. Just try a dozen strokes from each end then re test the tool. The edge you will have created wont last long but it should cut a very fine shaving leaving a good finish. This technique forms a work hardened burr just right for fine shaving.

 

[Spindle]

Hi

Quick graphic attached to show where I consider the optimal scraper presentation to be when working internally and externally

Regards Mick

 

[Spindle]

Hi

Don't get too hung up on raising a burr - in woodturning any burr you do raise is almost instantly knocked off in use. The efficiency of the scraping action is governed by the sharp intersection of the top and front planes of the scraper.

Regards Mick

 

[Soylent1]

Thanks Spindle,
As your diagram, I was probably trying at about the 7 o'clock position I don't know why? I have just tried as your diagram and it does seem much better I get a really smooth finish, perhaps I was hoping I could use the scraper to remove more wood in one go than it's designed for?

Regards Tony

 

[JustBen]

There's meant to be a burr?! Lol

I've never had one, well not that I've noticed.

 

[CHJ]

There's meant to be a burr?! Lol

I've never had one, well not that I've noticed.

Normal low pressure grinding with the scraper supported on a standard flat rest will most likely leave a very small burr on the top edge, can be an advantage for a very fine finishing scrape similar to the use of a cabinet scraper, but as said it will be very fragile and rapidly disappears in use.

It is possible to raise a more significant burr even on HSS scrapers with the use of a Carbide Pin/Pillar
But to be frank I have not done anything significant to warrant any attempts at fine finishing for some considerable time.

I think most turners, especially with green wood turnings find the careful use* of a burred cabinet scraper just as, if not more effective and easier to manage.

A rear edge wooden protection buffer to prevent slicing of the hand is prudent.

 

[Soylent1]

Ok,

So I don't need a burr - that's good! I think the scraper would have ended up too short to use if I had kept trying!

and nobody really uses them when they get good, as they have acquired the skill to get a good finish straight from a gouge etc..? is this right? As for me I think I will be able to use it to get rid of lines and not as a replacement for a gouge(don't get me started on the gouge!) as I hoped I could use it for, so all is not lost.

(scraper in the bin)

Thank you all for your comments.
Tony

 

[woodyturner]

A square end scrapper is designed to be used on the outside of a bowl so only a small part of the cutting edge is in contact with the wood if it is unnamed then chances are it is carbon steel and this could be why it is losing its edge so fast

 

[Spindle]

Hi

I use my 1 1/4" square scraper to finish large platters and table tops - hence the very slight round nose grind which doesn't affect it's performance on external curves.

Regards Mick

 

[Jethro]

Don,t bin it, as you get more experienced at this woodturning you will find a use for it.
You can regrind it to any shape, you don,t have to keep it square.



Geoff