HSS DIY scrapers

[hughie]

I have been making my own scrapers out of old cold saw blades for several years now. Cold saw blades 300-400mm dia x 2.5-3mm thickness are made from High Speed Steel hardened and tempered to around 68 Rockwell C.

This version is the latest and has a hollow handle covered in foam for ease of grip. Hollow to allow the scraper shaft to extend to meet the depth of the turning, the shaft consists of 16mm of high tensile shafting with a length of 300mm. The scraper blade is mounted on a detachable head so it can be quickly changed if necessary, the blade also can be removed for sharpening and rotated so the whole edge can be presented
.
The HSS being thin allows the blade shape to be altered to any shape or form

Sharpened angles are 85-90 and 20', the 90' is used for finished shear scraping and the 20' can also be used for finishing but generally its use for shaping and contouring. 85-90 you can use both sides of the scraper and so doubling up on the edges

 

[hughie]

The original scrapers I used flat bar and a set length on a wooden handle. They worked well but the final design is a lot more versatile and can reach deeper. The angles shown are the first attempts, roughly 30 and 45' simple attachment, limited adjustment.


The later version is greatly improved with greater movement, larger centre hole, swing arm, extendable shaft




The benefits of these scrapers are firstly the old blades are freebees as they are normally thrown out by engineering companies, they a re readily shaped to whatever shape is wanted and HSS quality is some of the best if not the best. I have passed several sets around to other local turners for testing, all have given them the thumbs up.

 

[Pat Wisniewski]

How are you cutting out the shapes?
Waterjet? Grinder? Metal-cutting bandsaw?

 

[John K Jordan]

I have been making my own scrapers out of old cold saw blades for several years now. Cold saw blades 300-400mm dia x 2.5-3mm thickness are made from High Speed Steel hardened and tempered to around 68 Rockwell C.

Ah, with the photos I now understand the types of scrapers you referred to in the other thread, "How to hone round nose NRS", post #10 and #15.

I have a some similar to that, some I made from various stock, usually hold them with a screw and washer in Sorby handles that came with round and teardrop scrapers. Some are about 1/8" thick, some thinner. I don't bother with grinding angles on the edges, sharpen them all at 90 deg. I use no burr, ground or burnished. They work well for me on the insides of things where I don't want to use what most call NRS flat on the rest: just rotate the handle as needed for a very smooth surface. I occasionally make another one with a special shape as needed.

 

[Ricc Havens]

Very interesting. Question - what kind of foam are you using for the handle? IS the foam a solid tube that has to be slipped over the whole tube or is the foam slit down the side and you wrap it on and glue it in place? I have made a couple handles out of aluminum tubing and want to cover them. I know you are in the wonderful land of Oz. But if you have a link to aussie amazon or other supplier I may be able to find something similar here in the US. THANKS!

 

[hughie]

Very interesting. Question - what kind of foam are you using for the handle? IS the foam a solid tube that has to be slipped over the whole tube or is the foam slit down the side and you wrap it on and glue it in place? I have made a couple handles out of aluminum tubing and want to cover them. I know you are in the wonderful land of Oz. But if you have a link to aussie amazon or other supplier I may be able to find something similar here in the US. THANKS!

Ricc, The foam were eBay and at times samples from the USA all were sold as tool handle grips. I have on occasion used the bicycle handle bar wrap, it work well but the ends need taping

https://www.amazon.com.au/uxcell-Insulation-Lagging-Utensils-Fitness/dp/B0D9W949GN?gQT=1

These are short ie 10" mine were 18" as I like long handles. I use them as is, no slitting, if too tight you can expand the foam with compressed air as it goes on. The tricky part is getting the right bore so it will grip your tube. I use 25mm stainless tube with foam 1.25" OD with a thickness of about 5-6mm. This will stretch with shop air and grip the handle really well.

 

[hughie]

How are you cutting out the shapes?
Waterjet? Grinder? Metal-cutting bandsaw?

Pat, The there only two ways to cut the HSS that are reasonably priced. Water jet for me is hopelessly expensive, instead I use plasma arc it cuts it like butter, failing that a 4" grinder with the thin cutting blade 1mm . Without plasma arc making a hole can be challenging, in the past I have burnt hole in HSS with an arc welder.

 

[hughie]

Ah, with the photos I now understand the types of scrapers you referred to in the other thread, "How to hone round nose NRS", post #10 and #15.

I have a some similar to that, some I made from various stock, usually hold them with a screw and washer in Sorby handles that came with round and teardrop scrapers. Some are about 1/8" thick, some thinner. I don't bother with grinding angles on the edges, sharpen them all at 90 deg. I use no burr, ground or burnished. They work well for me on the insides of things where I don't want to use what most call NRS flat on the rest: just rotate the handle as needed for a very smooth surface. I occasionally make another one with a special shape as needed.

John, rough grinding with 80 grit or coarser will leave a half decent burr, although short lived on hardwood and I make a large hole in the blade to allow a fair amount of movement and like you I use a washer for clamping. I find the two angles work well, one is fine work while the other is more bulk removal

 

[Ricc Havens]

Ricc, The foam were eBay and at times samples from the USA all were sold as tool handle grips. I have on occasion used the bicycle handle bar wrap, it work well but the ends need taping

https://www.amazon.com.au/uxcell-Insulation-Lagging-Utensils-Fitness/dp/B0D9W949GN?gQT=1

These are short ie 10" mine were 18" as I like long handles. I use them as is, no slitting, if too tight you can expand the foam with compressed air as it goes on. The tricky part is getting the right bore so it will grip your tube. I use 25mm stainless tube with foam 1.25" OD with a thickness of about 5-6mm. This will stretch with shop air and grip the handle really well.

Thanks Hughie

 

[John K Jordan]

John, rough grinding with 80 grit or coarser will leave a half decent burr, although short lived on hardwood

Thanks. As mentioned, I have similar scrapers which work well, always remove grinding burrs. If the inside of a piece is hollowed nicely they are perfect for a smooth surface, especially when openings are big enough to look and feel inside with a finger. That's good info, but I have no reason to make more.

Depending on the size, shape, and wood, I also sometimes shear scrap the insides with a Hunter tool or the wing of a spindle or bowl gouge. Whatever works.

I sharpen the thicker (1/8") scrapers with techniques described by StewMac on their web site. For any not aware, these are excellent scrapers, sold to people who make fine wooden instruments. Not cheap but I think worth it. StewMacs video shows them in use of flat wood but they work well with turnings. I use the that same sharpening methods on all thicker scrapers, with an 8" wheel but CBN. Note they remove any grinding burr, and for good reasons. I burnish a burr on the thin curved scrapers.

I bought the set of three but have reshaped the rectangular one to better suit me.

StewMac Ultimate Scraper - StewMac

The best tool for smoothing and shaping archtops, and a great all-around scraper.

www.stewmac.com

As I said, I have all I need and don't plan on making more. But if anyone nearby wants to, bring the steel and I'll provide the plasma cutter.

BTW, on the subject of scrapers: using a sharp gouge upside-down also works well for scraping in certain situations, especially for tight curves.



JKJ

 

[Michael Anderson]

BTW, on the subject of scrapers: using a sharp gouge upside-down also works well for scraping in certain situations, especially for tight curves.

Hmm, never considered that. Will have to give it a try.