Author Topic: Power scraper and flaker mecanism difference?  (Read 730 times)

Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2438
  • Country: fi
Power scraper and flaker mecanism difference?
« on: January 11, 2020, 04:00:42 PM »
I might be missing something?

I am trying to understand how power scraper and flaker mechanism works and what sort of dance the blade makes.

Judging from Biax patent drawings drawings and pictures there are in the net, I think that that the blade stem movement is strictly recipocating cyclic movement. Like this:


As far as I see there is no other movement than linear movement. There is that orginal wobble drive mechanism and several DIY projects have scotch yoke. Is there any intricasies or just throw and rotating speed?


BUT flaking seems to be more complicated?




There seems to be slight see-saw movement and linear movement combined. Haven't seen any description on this mechanism, bit can imagine one.

My question is actually. Is there any magic in it?

Offline Pete.

  • Hero Member
  • *****
  • Posts: 1016
  • Country: gb
Re: Power scraper and flaker mecanism difference?
« Reply #1 on: January 11, 2020, 04:37:28 PM »
The flaker is as simple as it gets compared to the scraper, and would be very easy to replicate. There's a swash plate on a spindle that turns, and this pushes on a bearing to make the round shaft go out. Your own weight on the blade pushes it back.
There's a pin sticking out of the end of the shaft that pokes through a hole in the arm that holds the bearing. as the shaft turns it rocks the arm side to side slightly.

The cutting blades unlike the scraper ones have a radius on the front and on the bottom. The front radius controls the size of the half-moon scrapes. Everything else (stroke and rocking motion) is fixed.

Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2438
  • Country: fi
Re: Power scraper and flaker mecanism difference?
« Reply #2 on: January 11, 2020, 05:00:06 PM »
Thank you. Pretty much as I though and after a bit of googling I found pretty good thread that has dimenssions:
https://www.practicalmachinist.com/vb/machine-reconditioning-scraping-and-inspection/shop-made-power-flaker-320189/

Any idea of "rpm" of the scraper/flaker?

How does the scraper/flaker blade shape differ?

Pekka

Offline Pete.

  • Hero Member
  • *****
  • Posts: 1016
  • Country: gb
Re: Power scraper and flaker mecanism difference?
« Reply #3 on: January 11, 2020, 05:58:28 PM »
I just checked and the newer ones ARE variable stroke and rpm, according to the website. 0-1800 strokes/min. Mine is fixed, not sure what rate but it's gotta be 1400-1600. I have some flaking to do tomorrow I'll take a look.

The scraper blades are dead flat with the (also flat) tip straight out from the end. The flaker blades have the tip slightly under-slung on the blade and the bottom of the tip has a radius.

Offline Pete.

  • Hero Member
  • *****
  • Posts: 1016
  • Country: gb
Re: Power scraper and flaker mecanism difference?
« Reply #4 on: January 11, 2020, 06:02:59 PM »
BTW I remember that thread when it originally came out. The guy made a great passable effort of a home made flaker but made one fundamental mistake - he put the blade on top of the rocking shaft instead of underneath it. That changes the whole motion of the tip. I'm surprised that no-one pointed it out at the time.

Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2438
  • Country: fi
Re: Power scraper and flaker mecanism difference?
« Reply #5 on: January 11, 2020, 06:18:36 PM »
Thank you very much. That gives me somethng to work on.

Offline Pete.

  • Hero Member
  • *****
  • Posts: 1016
  • Country: gb
Re: Power scraper and flaker mecanism difference?
« Reply #6 on: January 13, 2020, 06:45:53 PM »
No problem. By the way I was wrong about my flaker - it IS variable speed 0-1600strokes/min but the stroke is a fixed length.

Pete.

Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2438
  • Country: fi
Re: Power scraper and flaker mecanism difference?
« Reply #7 on: January 14, 2020, 02:20:17 AM »
Thank you. I have been toying with this idea a little since I got my 3D printer, that should allow be to check mechanism and timing without huge comitment.

I started looking for appropriate donor for a appropriate motor, possibly even slightly smaller that biax has, somewhere 200-400w and shaft output around 0-2000 rpm (probably 500-1500 would be great) also original looking form factor would be nice....it does not look trivial. Many of the power tools have bulkier and higher reving motor (like angle grinders) or are way too bulky (like polishing machines, with added angle drive, or when form factor and wattage is right, speed is off the wall (like most of the grinders/sanders). 3-phase induction motor or servomotor starts to look attractive, but would need an commitment. Some hand held power drills seem to have about right size and speed, but the chassis would then be fabricated including the gearbox housing....I think the wobble drive and it's housing should be enough work.

Lazy hunt for the motor is on and in meantime I'll check what could be checked before buying a motor (and prepare for motor output shaft rotation direction).

Pekka

Offline Sea.dog

  • Full Member
  • ***
  • Posts: 111
  • Country: gb
Re: Power scraper and flaker mecanism difference?
« Reply #8 on: January 14, 2020, 06:17:14 AM »
I'd love to know what an "Optical Pleasuring Surface" is  :scratch: