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  1. #1
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    Default Jamieson signature bowl gouge made by Doug Thompson

    Four of us on the forum pitched in on combined postage to buy a Lyle Jamieson designed 5/8" bowl gouge made by Doug Thompson. Unlike Doug’s other tools that can be purchased here through SE Qld Woodworking Supplies…

    https://www.woodworkingsuppliesqld.com.au/Woodturning-Chisels2/Thompson-Turning-Tools

    …this gouges can only be purchased directly from Lyle…

    https://lylejamieson.com/product/signature-jamieson-grind-bowl-gouge-thompson-handled/

    Many of us on the forum have one of Doug Thompson’s bowl gouges with his standard V flute profile, but I wanted to try this gouge with Lyle’s flute design which is also made with the same powdered metal V10 HSS and cryogenic treatment as Doug’s other turning tools.

    Lyle promptly dispatched the gouges on receiving our order, but it then took seventeen days from parcel lodgement by Lyle until it was air uplifted from Los Angeles and then a further nine days for the parcel to be delivered to me here in Adelaide, so 26 days all together. You wouldn’t want to have been in a hurry to get this gouge!

    They come with Lyle's preferred grind for the students he teaches. He claims his grind will do all of the commonly used cuts and his students will only need this one gouge grind for everything. I measured the nose bevel angle and it was just below 60 degrees…

    I like to give the gouge makers the courtesy of trying out the grind they send on their gouges before changing them to suit myself.

    I didn’t bother polishing the tip end of the flute, but will have to do that at some stage as Doug Thompson leaves milling tracks in the flutes of his gouges that are about the same as the old P&N gouges, which always needed a fair bit of work to grind/polish out.

    To resharpen it I set my Tru-Grind jig leg on setting 6 and adjusted the slide to kiss the side bevels as explained on pg.11 in the Tru-Grind manual…

    https://www.woodcut-tools.com/uploads/6/3/2/5/63254223/woodcut_trugrind.pdf

    Here is the end view of the Jamieson flute profile on the right and the standard Thompson V flute profile on the left.

    As you can see there are some serious milling/grinding tracks in the Jamieson that will need some work on them as did all of the Thompsons when they first came.

    I will comment on the Jamieson flute profile in some detail later and only say at this point, if that is parabolic flute profile, as Lyle claims, then I need to go back to Conic Sections 101.

    Looking at the edge profile viewed from above you can see that it faithfully follows Jerry Glaser’s guidance on mirroring the cutting edge as seen from above with the flute profile as seen from the end view, at least as the starting point with any bowl gouge. Here it is seen from above…

    The significant thing to note about the two gouges side by side in the above photo is how deep the Jamieson flute goes into the bottom of the gouge to achieve that wider flute. As a result, there is less metal left in the gouge which does leave it feeling less solid than the Thompson standard V.

    Lyle claims that this gouge has the widest flute of any 5/8" bowl gouge being sold. It measured about 12mm across and is about 1.5mm wider than the standard Thomson 10V and up to 2mm wider than some of my other 5/8" bowl gouges (Thompson 15V - 11mm, Ellsworth Crown - 11mm, VM 11mm, Thompson 10V - 10.5mm, D-Way - 10.8 & 10.6mm, HT - 10.6mm, Woodcut - 9.8mm), so he is probably right there with that claim.


    Whether there is any benefit from that extra wide flute might become obvious when I give it a test run, which I will report on in my next post.

    Stay sharp and stay safe!

    Neil



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  3. #2
    Join Date
    Apr 2007
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    Default

    For a test run I used the Jamieson gouge as received on some very well seasoned oak blanks.

    I must say that I don’t think Lyle’s grind will become my favourite, but given the grind was selected by Lyle for his novice student and it's a very long time since I was a novice turner that may not be surprising.

    To me that grind didn’t seem to do anything particularly well, so a bit of a compromise, which might be OK for new turners that need a grind that is “easier to control”.

    I then changed the grind to my workhorse grind of 65°. This is the grind that I use for doing all of my hogging down green turning and for finishing the inside bottom of bowls when final turning and for final fine slicing cuts using the wings for final finishing cuts on the outside of bowls.

    The change to 65° immediately improved the performance of the gouge for me on those cuts that I’m very familiar with and the gouge started to perform closer to the way my other Thompson bowl gouges (TBGs) do.

    I then did a side by side comparison between the standard Thompson V and the Jamieson bowl gouge (JBG) . As both are made from the same V10 powdered metal steel and cryogenic treatment this was not about how long each would cut, but more about how the different flute profiles performed.

    With both gouges ground to my 65° bevel grind, and taking alternating cuts with the two, I first did some hogging down push cuts. I found the JBG was noticeably more controllable and I was able to comfortably take 12mm wide cuts.


    This was a surprise to me as the JBG is lighter (and more flexing) than the TBG. Typically lighter gouges get buffeted about doing heavier cuts. So, obviously the more open flute profile on the JBG contributed to its stability in those heavier cuts. There was also a noticeable difference in the shavings that came off each gouge, shavings off the JBG on right...


    I put that difference down again to the slightly more open flute profile on the Jamieson. For what it is worth, the TBG ejected its shavings much further than the JBG. Not that you would select a gouge specifically for that, but it was nice to not have to clean up so far away from the lathe with the JBG.

    On finishing cuts on the outside, which I do with a slicing cut back along the wings, the JBG gave an acceptable finish, albeit with wider shavings.

    With inside plunge/push cuts the JBG seemed to be less aggressive than the TBG, producing finer shavings and some vibration. Through the inside transition and across the bottom the JBG did as well if not better than the TBG. It also handles the reverse cut back out through the transition area quite well. Where the JBG struggled was with coming back up through the inside walls with a reverse scraping cut… it complained audibly at that.


    55° Bevel Grind

    I then reground both gouges to a 55° bevel. My impression with this grind was that the two gouges were much of a muchness. Here are the shavings off both from outside cuts, which indicates a similar cutting action.



    40:40° Bevel Grind


    Skipping a 45deg bevel and going straight to 40/40… if you are after an acute angle push cut why not go with a dedicated 40/40 grind. It won’t do anything else well other than a push cut, but it does that very well.

    I don’t have the 40/40 grind on any of my TBGs, but do have it on my parabolic Vicmarc and Woodcut gouges. Stuart Batty, the proponent of this grind recommends parabolic or “elliptical” (his words) flute profiles for this grind. I don’t think the JBG has either of these flute profiles myself (more on that later) but some are giving their TBGs a 40/40 grind, so I tried it out on the JBG.

    The resulting finish was more than satisfactory, including on an interrupted cut…



    My Summary


    Although the flute profile on the Jamieson and Thompson BGs are only slightly different they do perform differently with some cuts.


    • The lighter weight from the deeper and wider flute on the JBG complained a bit on some internal cuts, but was surprisingly up there with the TBG on outside hogging push cuts that were comfortable and very controllable.


    • The Jamieson also performed well with my 65° bevel grind on inside bottom of bowl cuts.


    • I wouldn’t use it myself for shear scraping, but would find it equally satisfactory for fine finishing slicing cuts.


    • If your preference is for a 55° grind you may find that there isn’t much difference between the two flute profiles.


    • I haven’t tried a 45° grind on it yet, so can’t comment on that.


    • The JBG performed very well with a 40/40° grind, but I can’t comment on how a TBG would go with that.


    • On price there isn’t much difference between the two, but buying from the local supplier of Thompson tools would be quicker and easier.


    Am I happy with my purchase? Yes, more than happy. I’m unlikely to leave the dedicated 40/40° grind on it and will probably take it back to my preferred 65° grind now that I know how well it performs with that on outside hogging push cuts.

    Of course, we all turn a little differently and others may have a different experience with this gouge. I will be interested to hear from the others on the forum who also got one of these Jamieson BGs


    ~~~~

    More comments on how I would describe the Jamieson flute profile in my next posting.




    Stay sharp and stay safe!

    Neil



  4. #3
    Join Date
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    Thumbs up

    Thanks Neil, I really enjoyed and appreciated the detailed review.

    Cheers,
    Peter

  5. #4
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    Default

    Wow this blows my mind - thankyou for the technical detail, it's very educational.

  6. #5
    Join Date
    Apr 2007
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    Default 45° grind

    I did go on to change the grind on the Jamieson BG to 45° on its way back to 65°. I already had a Thompson ground to 45°, so was able to do a side by side comparison of the two gouges, again using the same very seasoned oak.

    Doing push cuts up the outside with alternating gouges gave a good finish off both that was more than ready for sanding…

    On the inside, the finish off the two gouges from push cuts down the upper inside of the test piece were also equally satisfactory, although the Jamieson did start to vibrate and complain at times.

    However, there was a distinct difference between the two gouges when starting the inside cuts; the Thompson was precise and crisp in starting each new cut at the rim even when taking the rim thickness down to 2-3mm, while the Jamieson was very inclined to want to 'skate' away from the selected entry point. That would come from the difference in the tip geometry of the two gouges.

    Stay sharp and stay safe!

    Neil



  7. #6
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    Default

    On the Jamieson and parabolic flute profiles, here is the description that Lyle gives to the flute on his gouge…

    [It] “has a better flute configuration—Not a “V”, not a “U” shape … It has a wider, parabolic flute shape than any other gouge made today”
    I don’t think that Lyle is right about his gouge having a ‘parabolic flute shape’. Here is an interactive graph of possible parabolic profiles and no matter what value you put into the alpha parameter (other than zero) the sides of the parabola can approach a straight line but never become fully straight…

    https://www.desmos.com/calculator/zukjgk9iry

    A parabolic flute has a continuously changing curve without a circular (fixed radius) apex. Looking again at the flute profile on the Jamieson (on the right) alongside the Thompson (on the left) both gouges have very straight sides and a fixed radius circular area in the the bottom of the flute.…

    So, neither is parabolic, hyperbolic, elliptical, or for that matter catenary. That is not a criticism of the flute profiles on those two gouges, far from it as both are very nice gouges for various purposes… but more of a clarification in terminology.

    That flute on the Thompson has long been called a V flute and that term is an adequate description and avoids any confusion. Lyle’s flute is also a V with about the same angle between the straight sides (about 60° but that is just eyeballing it), but made wider to give a broader vertex (nose) and milled deeper to give a taller flute that is wider at the top.

    The difference between the Thompson/Jamieson flutes and the Henry Taylor flute (on right, which is parabolic) is very obvious when viewed endon and side by side…

    Peter Child had an image of his forged tool steel bowl gouge in his book from the 1970s that has a parabolic flute profile...


    And, there have been many bowl gouges with parabolic flutes since Roy Child (son of Peter Child) designed the original ‘Superflute' that was milled from solid bar and subsequently manufactured by Henry Taylor in Sheffield.

    Although quite different, both the Vicmarc on the top and the Woodcut have parabolic flute profiles...


    David Ellsworth has written that "The most important design change for the side-grind gouge has been the shape of the flute.” pg 18, December 2019 AAW Journal. The bowl gouge he designed is made by Crown for him, which also has a flute that is close enough to be called parabolic...


    The bowl gouges from Glenn Lucas, made by Hamlet, from Brent English at Robust and the Hamlet 'Masterflute' are also parabolic.

    Others on the forum may have some gouges with a parabolic flute that I haven’t mentioned here and might like to show us those.

    Parabolic flutes are versatile and more forgiving for novice turners, but may not provide significant advantages for experienced turners. About half the BGs in my tool rack are parabolic, but they don't get used any more than any of the others, but I reckon every turner should try at least one during their turning lifetime, so they don't die wondering if life could have been better with one or two of them...

    Stay sharp and stay safe!

    Neil



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