How do you know when a dubbing brush is done?

[FliesbyNight 0]

Ok, so I am almost finished making a dubbing brush machine. The trial run works fine but I just used string to make sure the static side pulled in with tension about 1 1/2"

My question is: How do I know when I have enough twists?  Run it until the wire breaks? Just figure it out with use?  The rotary force is an old sewing machine motor I had in the shop so counting is not really an option.

[Trouttramp 0]

This guy explains it well.

https://m.youtube.com/watch?v=Ij3EanMbM8E

[Poopdeck 0]

My hook on the non crank or static end is spring loaded. I twist until the spring is fully compressed. Most times the wire will break at the end since this is where the wire is the tightest so either way your most likely safe. It will however sometimes break some place other then the end which is why I just go until my spring is compressed. My table is 16” hook to hook with 1.5” of spring travel so it will twist up a 14.5” brush, or thereabout.

mines a hand crank and counting turns is not an option either. I have an old sewing machine motor that I was going to rig up but I found I don’t need it. A big hand wheel works fast. Buuuuuuuut, sewing machine motor speed is variable and is usually controlled with a foot pedal. If you don’t have a foot pedal you can simply wire a dimmer switch to it to where you can crawl the motor with the dimmer. 

[FliesbyNight 0]

21 hours ago, Trouttramp said:

This guy explains it well.

https://m.youtube.com/watch?v=Ij3EanMbM8E

Thanks, TroutTramp.  I'll check that out.

 

21 hours ago, Poopdeck said:

... I just go until my spring is compressed. My table is 16” hook to hook with 1.5” of spring travel so it will twist up a 14.5” brush, or thereabout.

mines a hand crank and counting turns is not an option either. I have an old sewing machine motor that I was going to rig up but I found I don’t need it. A big hand wheel works fast. Buuuuuuuut, sewing machine motor speed is variable and is usually controlled with a foot pedal. If you don’t have a foot pedal you can simply wire a dimmer switch to it to where you can crawl the motor with the dimmer. 

Thanks Poopdeck.  That's about the dimensions of my table as well.  I do have a variable speed motor with a foot pedal.  I was thinking of doing the hand crank version but I had this motor sitting on the shelf, see, and well...... I can't help thinkering.

[Poopdeck 0]

I hear ya and suffer from that same affliction.  I have a motor and foot pedal sitting under my bench. It was going on my brush maker but I prototyped the table with a hand crank just to make sure everything worked. It did and I never hooked up the motor. Good luck with the brushes.