Bill, a hammer-on is a slur on the fiddle. Some fiddlers create a fast, snapping sound with it to add attitude to the tune. Slow slurs are found throughout fiddle tunes. Being able to control it can be a good tool in your toolbox. To get your timing down between your bow and your fingers, on tunes, slow down a little. Practice scales going slower and say the note out loud matching your finger movement and your bowing as you say the note. You can use a metronome, too, to create the same coordination. The timing will come. It is great that you hear what is going wrong.
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