Aw man! Dan, if my sticks are as sturdy as the ones I buy online . . the only difference being the pre-notched cuts, why would these not work? What makes those sticks better? I'm asking honestly because I don't know. Everyone else such as yourself that does your own bars . . how do you make yours to be good enough? Is it the wood quality?
I am not saying yours will not work,they certainly will.
There are companies that make these moldings in stick length ready to miter.(very affordable too!)
I am more interested in seeing you get started down the right path to make this a profitable venture for you.
Spending alot of time on these bar issues just is not necessary when all you have to do is buy them ready to go.
For example. I pull an 8 foot length of moulding out of the bin. Cut the 4 pieces for a 16x20 frame on my dual miter saw then take it to my underpinner and staple it together. Takes slightly under 5 minutes.
With your miter saw and a staple gun it should take you less then 10 minutes to cut and staple your frame together. That's the maximum time you should be spending on stretcher bars,not a minute more.
The stretching is the next thing to master,then the folded corners,then the varnishing and finally don't forget that marketing.