#11: Post by Jake_G » July 25th, 2019, 7:49 pm

baldheadracing wrote: Interesting about the Loctite - I'll have to try that on my Vario-Forte the next time I wash the burrs.

Image: Forté Brew Burrs experiencing TBS

Image: Forté Brew Burrs cured of TBS

Image: Forté Brew Burrs with Belt-Induced Misalignment Interference Pattern

Image: Modified Forté Drive Pulley

The Loctite is not needed on the ceramic burrs as they have a solid bottom that seats firmly on the burr carriers. The ditting brew burrs have a raised seating surface on the outer perimeter which leaves most of the "mounting" surface (including all the area under the screws) floating above the burr carrier. I fashioned some .060" spacers to fill this void so that the burrs can be firmly secured to the burr carriers without fear of Taco Burr Syndrome.This is what the burr interference pattern looks like with the bolts tightened enough to induce TBS when the relief area beneath the burrs isn't supported:And here is what you get after supporting the relief area with a spacer and tightening the screws to secure the burrs flat against the burr carrier:Of course, to fix this issue, you must first align the lower burr carrier, which gets pulled out of alignment with the drive belt so that you get this when you first check your alignment:This is corrected by loosening the four screws that secure the grind chamber to the lower motor plate and then using the levers themselves to force the lower burr to square itself against the upper burr. Doing this will create an air gap between the grind chamber and the lower plate (as long as the screws are loose enough) and will force the bearing in the grind chamber into precise alignment with the bearing in the lower motor plate. With the levers held in place, gently tighten the grind chamber mounting screws in a crisscross pattern and you'll end up with an interference pattern that completely wiped the upper burr clean. You may need to loosen the belt a bit if the wear pattern still shows a half and half pattern and repeat the process to get it dialed in. The second photo above was achieved without using any shims for alignment. The burrs are fully seated in the carriers and the bolts are properly tightened.The spacers and the burr chamber alignment take care of two of the three major challenges to getting the Forté/Vario into a precise state of alignment. The third item turned out to be the most challenging as the drive pulley on the grinder I had the pleasure of getting to know was completely lopsided on the drive shaft. Correcting this required pressing a sleeve onto the motor shaft (it has a twisted star profile for inexplicable reasons...) and chucking the motor into a lathe to true up the motor shaft. You can see how eccentric the sleeve had to be to get the shaft and pulley turning true:After all of this, I was able to fully choke my GS/3 using the brew burrs even with a prolonged 2.5 bar preinfusion. Prior to alignment, even EKspresso was a tall order for this grinder.If Rao's Forté is a Unicorn, this one is an Alicorn.Below is a quick video of a teardown to remove the grinding assembly from a Forte. It was early in the morning and the family was sleeping, so there's no narration or voice over. SorryI'll add another video highlighting the alignment process when time allows.Cheers!Here is a video of checking the alignment with an ink test immediately before performing the alignment procedure:Here's another silent video. This time of the alignment process.And here is the ink test results after the alignment:Cheers!- Jake