Metal quality is key with any good puller which why striped the Harbor Freight puller forcing screw. Too much tolerance in the threaded puller bar creating a loose fit plus the forcing screw was very low quality. My machinist used much closer on resizing the puller bar and installed a high grade forcing screw. Just it last week om a very hard pull and no damaged threads.
In your image that puller hub look to be shop made vs commercial made so I asking is the center hole threaded for pushing against the shaft or are you using the nut to push? On this end I use my 1300 ft-lb impact on my puller which is also why I probably stripped the original forcing screw.
I do agree that coarse thread on regular screws and better due what I call sloppy tolerances. Last week I was a 3/8 screw for a 3/8 drilled hole for a tight fit. Every screw un-threaded portion I tried was so loose I had step up one size and fine tune the pivot hole in the bushing to match to clearance I wanted.
Even to find decent screws and other similar hardware I have to either go to the local Fastenal store or order them through my McMaster supplier where they don't sell the el cheapo hardware.
