Drum moving backwards during roast

Hi All,
I’ve done around 300 roasts on my R1V2. I posted recently about a couple of problems. One is solved but the other one remains. You can see that the result of the drum moving towards the rear is scoring of the aluminum pulley. I had attributed squeaking during the roast to the belt, but I now believe it’s this metal-to-metal contact. No beans ever drop out the front during the roast, and I can complete roasts without problems other than noted. What would cause this, and more importantly, what’s the solution? Do I need a shim at the rear bearing?
Thanks in advance for the help.
Eric


Definitely looks like scraping. If you are still under warranty, check with tech support about what you should do. Just so you don’t do anything to void the warranty.

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Well, usually, you just push it back into place. If it won’t go back, you’ve had some kind of problem putting the face plate back on. Either a cable is creating an obstacle, or it’s not aligned and tightened as it should be. If you push on the drum shaft from the front, does it bounce back into place? If not, you have a problem, if yes, you should be able to just push the pulley back in place.

Do you do this everytime you take off the face plate?

I generally check the clearance, and do a “press test” (as per the manual guidance for initial setup) after the plate is on.

What are you pushing?

Yes, as a matter of fact, I do that every time. Personally, I think that the laws of physics would impede the removal and reassembly of the face plate without moving the back pulley. As you will see, the drum will immediately sag, once you remove the face plate. When you’re putting it back on, you must raise the drum a bit and also screw it back into place.

As for what I’m pushing, again it’s the back pulley. The round thing in the picture above with a belt around it.

The last two responses brought up good points and prompted me to reevaluate the situation. I had assumed that the drum was moving backwards and contacting the pulley during roasting, but when I push the shaft from the front bearing as described in the manual, it moves back about 1mm and returns to the front position, just as it’s supposed to. When it’s pushed to the most rearward position it does not contact the pulley as I had assumed. I wondered if the “latching mechanism” of the rear cover was somehow moving forward to contact the pulley since it seems to correspond to the scored area on the pulley, but I can’t get it to move in that direction. I’m totally at a loss to understand what’s going on, so any suggestions, theories, or snide remarks would be appreciated.
Thanks!

Press test…sounds like I should be at the gun range. :laughing:
BTW, I’ve never had any problems with removal/replacement of the front cover and I pay particular attention to correct drum and shaft placement, knowing that it can be a problem. As far as I can see, they’re in their normal position and as mentioned, behave as per the manual.

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Please excuse me for asking this question:

Did you check to make sure that the set screw on the side of the pulley and the cap screw on the end of the shaft are tight?

If they is not tight, the pulley might be sliding on the axle shaft for the drum.

You can take a screwdriver and gently try to pry the pulley away from the drum. You sould be able to observe the pulley move about 1mm from the spring action, but it should not make contact with the framework for the squirrel cage.

The pulley should be fixed rigidly to the axle shaft for the drum.

Here is a photo of the end of the drum after removal.

In the photo the bearing is pushed most of the way to the end of the shaft. The pulley compresses the spring. The socket head cap screw on the end of the shaft and the side set screw should hold the pulley in place.

The spring is to compenste for the thermal expansion of the axle due to heat.