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TOPIC: CATRA HobbiGoni

CATRA HobbiGoni 1 year 4 months ago #10658

  • ThomasAscher
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I'm wondering if it might be useful to have a separate thread on the HobbyGoni? I know it appears a couple of times under other topics, but suggest it might be useful enough to deserve a topic of its own? I've owned mine for a couple of months now and only lately discovered what a valuable asset it is. For those who are not familiar with this device, it is a laser product for determining the existing angles on a knife, available from England, running about $150 including all the taxes and shipping to this country.

While in theory it only reveals angles on each side of the blade to within 2 degrees, I find with mine I can easily determine the angle accurate to 1 degree. More important, it reveals the quality of the edge. If the edge is perfectly ground, perfectly flat, the angle shows as a very tiny circle on the scale. If there's any kind of burr remaining, or secondary angle, or rounding of the edge, the point of light shows as more than one point, or as an elongated blur of light on the scale. Sometimes, I've had difficulty telling if there is still a slight burr by feel; the HobbyGoni clearly shows if there is a burr remaining.

While $150 is not a trivial expense, I've spent far more than this on various stones and strops which I haven't gotten the full benefit from, as I have not been able to tell if my technique is good enough to get the edge I had hoped for. I've found that even under a microscope, I've been able to tell how polished my edge is, but not how precise in terms of coming to a point, creating a flat grind, eliminating burrs, or achieving the angle I desire. The HobbyGoni is better for these issues, and also more accurate than a marker, as well as much quicker, for determining angle. The problem with using a marker for determining angle is it involves destructive testing. The HobbyGoni gives an answer much quicker and without altering the edge.

The other aspect of this instrument that is important to note, is that on first use, with new knives direct from the manufacturer, the Hobbigoni appears to give very crude, not useful measurements. This turns out to be the fault of initial grind, not the Hobbigoni. The Hobbigoni is simply revealing what is there. If the initial grind is crude, the pattern shown by the instrument looks crude as well.

So much for my rant as a new convert. I thought might be useful for others.
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CATRA HobbiGoni 1 year 4 months ago #10661

  • KenBuzbee
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Got a link? Google can't find it.

Ken
玉鋼
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CATRA HobbiGoni 1 year 4 months ago #10664

  • ThomasAscher
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www.catra.org.uk/product_p/cuhg.htm

Sorry for the misspelling in the heading. Couldn't find a way to edit after posting!

Tom
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CATRA HobbiGoni 1 year 4 months ago #10667

  • JoseFuste
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I just ordered one...somebody mentioned before in another thread. I haven't heard anything negative about it...

Thanks for the feedback....:cheer:
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CATRA HobbiGoni 1 year 4 months ago #10669

  • EamonMcGowan
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Tom does it show each problem independently or do you just know you have a problem? Sorry for not getting it? I'm a confused? I'm a gadget lover and sure I want one! Just confused LOL!!!

On a side note? Can someone please share with me how you select text out of a thread and quote it? I'm trying to cut and paste and then use quote button and am not getting it right?
The definition of insanity is to do the same thing over and over again and expect a different result?
An old Irish toast, May the wind always be at your back, may you always have work and may you be in heaven a half hour before the devil knows your dead. Cheers!
Last Edit: 1 year 4 months ago by EamonMcGowan. Reason: messed up quote
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CATRA HobbiGoni 1 year 4 months ago #10670

  • ThomasAscher
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When you receive the HobbiGoni termed a "Laser Knife-Edge Protractor" you find an enclosed booklet of User Instructions. It shows diagrams and patterns of reflections from thin and thick knives, curved or hollow ground surfaces. The key item mentioned is that "the closer the reflection is to a full and bright dot the nearer the surface is to a perfect mirror polish."

In my experience, I found that I needed to use the instrument on various knives, looking at various patterns to educate myself on what I was seeing and why. If I saw a bright dot on each side of the scale, I knew that I had achieved a flat, highly polished surface on each edge. If I found that I had more than one point, or an angled line, or a blurred, wide reflection, I knew that I had something less than perfection. Over time, comparing the reflections from the laser with what I was able to observe about the knife edge under a microscope, I've educated myself regarding what imperfections of sharpening technique correlate with what patterns of reflections in the HobbyGoni.

One of the surprising things I discovered was that a couple of Masamoto knives I had newly acquired from Japan, one an HC, the other a VG, had rather blurred, indistinct reflections when viewed with the HobbyGoni. My initial reaction was that the HobbyGoni was a rather crude, not very useful instrument. Over time, re-sharpening, polishing these knives, I achieved much more precise reflections with the HobbyGoni confirmed by real-world improvements in cutting performance.
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CATRA HobbiGoni 1 year 4 months ago #10675

  • mark76
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I've got one, too. I mainly use it to determine the angle on knives I sharpen for the first time. Way quicker than using a Sharpie.

It works very well provided the bevel is regular. If it is very irregular, you see the result with the goniometer :) . Also convex edges sometimes provide an interpretation challenge.

Eamon, the quote button should work. But you can also manually quote text with the "[ q u o t e ]" tags (without hyphens and spaces). E.g.

[ q u o t e ]Nice goni[ / q u o t e ]

results in
Nice goni
Last Edit: 1 year 4 months ago by mark76.
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CATRA HobbiGoni 1 year 4 months ago #10676

  • cbwx34
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Thanks for the review.

Here's a link with a bit more info... Laser Knife Edge Protractor

CATRA has some interesting equipment.

(I also corrected the thread title.)
Last Edit: 1 year 4 months ago by cbwx34.
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Re: CATRA HobbiGoni 1 year 4 months ago #10677

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Thanks Curtis. I should have done that :-).

I just remembered I once did a blog post that featured the goniometer (and the challenges it sometimes poses). It may be interesting if you wonder how it works. It is here.
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Re: CATRA HobbiGoni 1 year 4 months ago #11046

  • JoseFuste
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Tom,
I just received mine today and would like if you can post some pictures of yours actually with some knives. I also read on the instructions guide that one of the advantages is that you can measure each side independently and it illustrate how, but it seems they are referring to a different instrument. Have you tried that before?
Thanks,
Jose
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