You good otherwise with sharpening edged tools? Since I can't look over your shoulder I have to start with basics....

Read a bit into this forum thread too. Seems recent 151's may not be fully finished, making proper blade adjustment impossible. Yours may have similar issue.

This one suggests they should be pushed like most western-style plane, yet they show one being pulled... and I've never had luck trying to push one.

And the 151's work with their bevel down, facing the workpiece, not up as in the wood-handled two-piece styles. Easy mistake to make during reassembly if you're new to using one.

Bronze spokeshave on the left is the Boggs shave from Lie Nielson. Can't get any better that that period, full stop. The other two are from Veritas, Lee Valley. They are really good. Boggs shave is available with flat and curved sole. The curved sloe is pretty shallow and won't make a small radius concavity.
https://www.lie-nielsen.com/nodes/4091/spokeshaves

Veritas makes a variety and the curved sole is a much tighter radius.
https://www.leevalley.com/en-us/search?query=spokeshave

I've used a lot of brands, this is what I still have in my cabinet. IMHO the one you have blows.

Cheers,

e 

Eric wrote "  IMHO the one you have blows."

Man, I get goosebumps when you talk all technical like that :-)

Laszlo

   I have a Stanley spokeshave. Not sure about the number but it looks just like pictures of the 151. I used it to make my oars, my mast, and my spars. I've recently been using it to make wooden longbows. All these tools can be tricky to sharpen. Spokeshaves can require delicate adjustment, but I get long, beautiful, tightly-rolled curls when mine is properly adjusted. My advice, keep trying on test pieces to see if you can get it right. Of course, you might have a defective tool, but don't leap to that conclusion.

   I have one too. It gets "chattery" if I get greedy and want to take too big a curl off the work.  It also needs the work firmly clamped down. 

I agree with Burch2,  try adjusting your 151 to take a finer cut.  Check the links to see how I rounded my birds mouth mast with a Stanley 151 spokeshave.     

https://photos.app.goo.gl/2FEr14kkM2EFG1qK9

https://photos.app.goo.gl/baixEimAKQcg5Um4A

So actually, I never got the spoke shave to work well but I got really good with my draw knife and block plane.  I think the final result came out pretty nice.  Now I I hope I can make the other one match it LOL

https://share.icloud.com/photos/0JMwQaW7NpXmH7t_qyLQdviww   

After making sure my spokeshaves are sharp and properly adjusted, I get much better results if I hold the tool handles with my middle, ring and little fingers. I then have both index fingers and thumbs holding the center portion of the tool while also being in contact with the work. Holding the tool this way gives very fine control. Try it with some scrap. This works for me whether pulling or pushing the tool.  

Regards,

Brian