Thread: Thompson 5/8 U gouge - first impressions

Send it to me Ern

Kind of you Pat.

I've already sent you one gouge. Worn it out already? ;-}

Just trying to help you Ern. The little Glaser is quiet comfie, really only being used to shear scrape smaller bowls.

Any pics of the Thompson?

Originally Posted by rsser

Letzzgo asked me ...

The gouge comes with a 60* bevel angle at the tip. The flute is reasonably clean in terms of milling marks. There's a long even radius cutting profile.

From the bowl edge to about the mid mark it worked well. Then geometry got in the way. The handle end started to foul the bed.

The handle is about a third longer than the steel, and the banjo top on the VL175 is quite high in relation to the swing.

There are a number of options to change this geometry.

My inclination is to shorten the handle.

Interesting

Mine wasn't ground ex factory. I had to grind it to suit myself. Hence my comment that it didn't work too well initially, I'd not fully/properly ground it
I put a 15" jarrah handle on it. Lovely. In fact after using it to rough down today, I thought the P&N handle on the 1/2" a little wimpy. I'm not sure I'd want a shorter handle, but then I'm still finding my comfort zone. I didn't use it much inside the bowl as I was mainly roughing down and coring.

Your comment on another thread about diamond hones was interesting. I tried to touch it up during the job with a diamond hone to little effect. Seems to be a harder steel then the P&Ns

Originally Posted by rsser

Letzzgo asked me to post on this and I've had a play hollowing an open bowl 25 x 10 cm.

Yes, Ern, I think I asked for a comparison in performance between the 5/8" V and 5/8" U Thompson bowl gouges. I suppose for a proper comparison both gouges would require the same grind. I'm not sure if this is feasible?
How much shorter would you need to make the handle to avoid fouling on the bed?

John

Originally Posted by rsser

My inclination is to shorten the handle.

...or turn outboard where the handle won't bump anything...
.

Yes, I'd swivelled the head out Neil but still had probs within the reach of the banjo.

Outrigger would be an option as you say; there are others and I need more time to play.

Pat, will post a pic later.

John, your question depends on the bowl form and I hesitate to speculate at this early stage.

Re comparo with the V, yes indeed, the grinds are different. The V had IIRC a longer bevel. Can no longer recall the wings form as I've reshaped the bevel a couple of times now.

The U has medium swept back wings.

Nick, yeah, you got one with the tip not ground if I recall. Not good.

My comment re polishing the flute and bevel was about Tormek paste by the way, not diamond (not yet).

Tip not ground didn't concern me, in fact I didn't think anything of it at the time. It might have been interesting to see how a Thompson grind looked.

By diamond hone I meant a little diamond stone I'm using to touch up the bevel whilst in use - to save a full grind. ie I'm too lazy to walk to the grinder


BTW if anyone wants the Tormek setup for the initial Thompson grind on the spindle gouge then I've got them. worked them out when he was here.

I prefer a V shape flute over a u shape anyday but when it comes to a U shape flute think... Push cut, Stu Batty finish cuts, roll the tool and use the large radius to your advantage to shear the wood. There are a hundred ways to grind that tool so I put a very basic grind on the tool without removing too much steel... IMO - I would free hand the grind like Stu Batty or Johannes Michelsen to 45 degrees to the flute then put a large secondary bevel to remove the extra stock. This is the grind I would use but freehand grinding is not for everyone.

P.S. - I'm working on a process right now to improve the steel... so far it looks good.

Thanks for the tips Doug.

I like a 60 degree bevel for some applications by the way.

I've just been doing some dry runs with the tool as it happens, before reading your post.

One option with this tool as is, is to pretty much have it horizontal and cut along the equator, rolling the tool to maintain the shear angle. (Talking about hollowing just to be clear).

I'm not comfortable with this approach as it isn't the way I normally work. It also requires an open form and my sense when I tried it once live in the first session is that it increased bowl flex. For some of the arc in the dry run I couldn't see what the edge was doing. But I'll play some more and look up 'Stu Batty finish cuts'.

Attached is a pic of the flute as best I could get alongside one of the 5/8 V gouge taken for the previous bulk buy.

Doug: is this what you meant by Stu Batty finishing cut ... ?

pull cut, shaft towards vertical, bevel rubbing up highish on the bowl outside, flute facing direction of pull.

Hiya Ern!

Just meandering OT for a sec... out of curiosity I googled Stu and found this link: Stuart Batty Woodturning Encyclopedia

If he follows through on the promised articles, I can see this site becoming a handy reference!

Hey Andy!

Yeah, I ended up there too.

Turning university?!

Got tickets on himself but sounds like he earned them ;-}

His finish cut a push cut using the radius, I'll see Stu at the end of the month and will try to get pictures of the grind.