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Thread: Hollowers for Wood Turning

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    PJs
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    Hollowers for Wood Turning

    This was another project for my Woodworking Guru friend which took me down many paths and taxed my skill levels and tiny shop pretty good. He wanted a set of 3, 3/8" hollower to match his 1/4" set of Keltons which are quite nice tools made in New Zealand. His weighted handle is double ended and accepts 1/4" (6mm) and 3/8" (10mm) tools. As I know less than a little about these I asked him to borrow the set for a couple of days to figure out what I needed to do to build them from 3/8" O1. Here is a picture of his 1/4" set. As you can see there is a shallow curve, a medium and an acute curve and the two latter are actually compound bends. We'll get to the relief angles later.

    Hollowers for Wood Turning-hollowers_org_small.jpg

    Basically I measured everything I could and actually made tracings of them in my engineering book. Also got the length specs from their website and scaled everything up to 3/8" including the radii. Upon close inspection I realized these actually have some (carbide probably) inset for the cutting edge.

    The first one I bent in the vice because it was so shallow of a bend and then started grinding, sanding and filing the flat and relief angles of the head. Once I got that done and pretty much sharp, I heat treated it by heating it cherry red, soaking for as long as I could then quenched in oil. No "Tinks" and a file wouldn't touch it. Then tempered it in the oven twice for an hour each at 450ºF and come to room temp both times. It was very hard but have no way of knowing how hard it actually is but will say that I had to start with a more course diamond tool to get it going...guessing maybe 50ish on the RC scale for my little setup. Worked it down until I felt it was sharp enough. Gave it back to him to let him try it before I went any further. Results were spectacular according to him and a piece of Dry Pecan (hard as rocks I understand) he took it to task with.

    Now I had to figure out how to do those compound bends and that's when I whipped up the "Rod Bender, Cheap n' Cheerful" I posted earlier. I also wasn't convinced my heat treatment would hold up so I ordered up some C2 Carbide from a great source I found on line. Centennial Carbide is a great source with good prices and Nice folks which I felt would be a good share here. Here is what I got but they also have fine grain also.

    Hollowers for Wood Turning-carbide.jpg

    For the other two I pondered milling them in the lathe first like I did for my Scraping Tools but argued against it because I could mess up the milling when I bent it and wasn't all that sure how it would go or how much scrap I might make. So Off to Bending them and it actually went pretty well but did have to heat them several times and bend again then move the rollers a bit to get them to match the scaled tracing profiles but as you can see the bends came out pretty good in my estimation.

    The basic profiling of the cutting area went pretty well but worked diligently to get them flat to get a good silver braze for the carbide. I thought I had a Dremel diamond wheel for the carbide but didn't so I ended up snapping the 1/16" off in the vice....not pretty but close enough to work. Silver soldered them and proceed to work the relief angles like I did the first one. This was tough because I couldn't work the carbide with my Silicone Carbide belts and ended up using my 120 grit diamond grinding wheel and a double sided lapping plate, 6" plate I made. I have 2, a 360 & a 600, then hand DMT's up to Extra fine (800-1000G). In some ways these were tougher to bring to edge and profile than sharpening my 27" Katana which has a convex profile and edge over a long run. because one little lack of concentration or slip with the diamond would cost me a half hour some times.

    Here are the finals of what I made for him.

    Hollowers for Wood Turning-hollowers1_web.jpg Hollowers for Wood Turning-hollowers2_web.jpg
    Hollowers for Wood Turning-hollowers3_web.jpg Hollowers for Wood Turning-hollowers4_web.jpg
    Hollowers for Wood Turning-hollowers5_web.jpg

    Hemingway this is turning into a book in my normal spew...bottom line I got the relief angles to what I thought was right and sharp as I thought was proper. Gave them to him to try...not as good as the first one. He recommended going to a relief like the round insert his Big O' Hollower uses which it 30º...so I did and it works. I still have some concerns this is too steep for some of the gnarly stuff he chews up but time will tell. One did get a tiny chip because the piece he was working had a crack all the way across and the interrupted cut of it gave it a beating but it's still cutting.

    Also wanted to share a couple of his pieces he's made. This is a small sample of his bowls but the Walnut cutting board I got from his is Awesome. He has an eye for finding the grain and bringing it out like few can, IMHO.

    Hollowers for Wood Turning-bowl1_web.jpg Hollowers for Wood Turning-bowl2_web.jpg

    So this just goes to show that old dogs can learn new skills...and have some fun along the way!

    ~PJ
    Last edited by PJs; 10-15-2016 at 10:14 PM.
    ‘‘Always do right. This will gratify some people and astonish the rest.’’
    Mark Twain

  2. The Following 6 Users Say Thank You to PJs For This Useful Post:

    C-Bag (10-15-2016), Jon (10-20-2016), morsa (10-17-2016), Paul Jones (10-15-2016), PFJohnson (10-22-2016), sossol (12-29-2017)

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    Wow, PJs,

    I am impressed with your fantastic workmanship and tools. Your silver brazed carbide "inserts" are perfect. Question: how did you slice the carbide from the raw flat stock?
    Thanks for and a great story,

    Regards, Paul

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    PJs (10-15-2016)

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    Thanks very much Paul, your praise means a lot to me! I did work hard to get the radius on the nose as good as I could and to get a cutting edge as far back on the straight side to help with material removal. Again I appreciate that You thought it was perfect.

    I ended up snapping the carbide off in the vice because it's brittle. It doesn't always break clean but used duck bills close to the vice jaws to minimize damage. They were a bit jagged and not a right angle like I wanted but long enough to fit without wasting it. I have since purchased a diamond cut off wheel for my Dremel but haven't had a chance to try it yet. I believe it should be able to cut cleanly through or at least score deep enough to get a clean snap.

    Thank you again! ~PJ
    ‘‘Always do right. This will gratify some people and astonish the rest.’’
    Mark Twain

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    Paul Jones (10-16-2016), PFJohnson (10-22-2016)

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    PJs,

    Good to know and I thought snap technique would work (and even better after making a scribed line). The Dremel diamond cut off wheel should make this easier. I have a diamond wet saw for tile and brick work that might work without shattering the thin carbide if the carbide strip is tightly held and sandwiched in between two 1/2" thick wood boards. This works well for cutting very hard and thin Italian ceramic tiles.

    Thanks, Paul

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    Quote Originally Posted by Paul Jones View Post
    PJs,

    Good to know and I thought snap technique would work (and even better after making a scribed line). The Dremel diamond cut off wheel should make this easier. I have a diamond wet saw for tile and brick work that might work without shattering the thin carbide if the carbide strip is tightly held and sandwiched in between two 1/2" thick wood boards. This works well for cutting very hard and thin Italian ceramic tiles.

    Thanks, Paul
    Good idea on the tile/brick saw...hadn't thought of that. I did have some concerns about creating stress fractures in the C2 by snapping it and it did create somewhat of a jagged edge but luckily left enough to grind down beyond those and to the Radii. Hopefully all moot now with the diamond Dremel wheel.

    Thanks again. ~PJ
    ‘‘Always do right. This will gratify some people and astonish the rest.’’
    Mark Twain

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    Paul Jones (10-17-2016)

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    Thanks PJs! We've added your Hollowing Tools to our Woodturning category,
    as well as to your builder page: PJs's Homemade Tools. Your receipt:





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