Repair Procedure
Roasting Drum Alignment Check

 DISCLAIMER: These tasks described here as well as the video presentations are not intended to be all-inclusive instructional videos nor offer advice on appliance repair. They merely illustrate the process. The information here as well as the videos take a lot for granted such as, but not limited to, your knowledge, ability, and safety around electrical devices, proper choice and use of hand tools, techniques to ensure personal safety, protection of property, fire safety, and more. By viewing. listening to, or watching these videos, and/or attempting the procedures on this page, or following any repair or maintenance instructions on the Hottop USA website, you assume all responsibility and release Hottop USA and all its employees and contractors from any and all liability. If you do not accept these terms and/or your local laws prohibit such a release of liability, you may not watch or use the information contained herein.

NOTE: Before attempting any cleaning or repair procedures, always read the full instructions and always refer to the step-by-step procedures. You can find these instructions in the Hottop Coffee Roaster Repair Procedures on our website. Additionally, our Video Education Center also has a number of helpful repair videos to augment those step-by-step repair pages. Refer to these before attempting any of these tasks and as necessary during the process.

WARNING
There are times when a roaster is partially disassembled when you may wish to run the machine. Usually this is during troubleshooting or after a repair to test your work before final assembly, but may also be done as part of these maintenance tasks. This may include a short test run with the rear cover removed or the front cover removed and other such procedures. The dangers when doing such testing may include, but are not limited to physical harm to you or others, fires danger, burns, electrical shock, and damage to the machine. The source of these dangers could include:
• Exposed electrical connections
• Moving parts such as the rotating roasting drum
• Heat from the heating element.
If you are unsure about the safety of any such task discussed below or any other repair or testing procedure, please feel free to contact us first at hottop@hottopusa.com and we will be glad to assist you.

    The clearance between the back end of the drum and the rear wall of the roast chamber is critical to the life of the Main (drum) Motor. Normally this is taken care of at the factory, but there are situations which may require a realignment such as after installing a new motor, installing an upgrade kit, or when metallurgical changes take place over time. Any scraping or rubbing sounds also indicate that an alignment issue exists. Refer to the following diagram and follow the steps below to diagnose problems and then proceed to properly align the drum in the roast chamber if necessary.
NOTE: Bold numbers and letters in green in the text (like this: (B) or (4) ) all refer to the following diagram:

CHECK FOR SCRAPES OR GOUGE MARKS
    Remove the front cover, bearing plate and roasting drum. Examine the following areas:
(A) The rear wall of the roast chamber for any scraping or gouging
(B) The inside surface of the bearing plate for any scraping or gouging
(C) The dimple in the bearing plate for signs of wear. While rare, if it appears elongated at or near the bottom of the dimple, it is an indication that an alignment problem exists. If you see such elongation replace the bearing plate before proceeding with any adjustments to the roaster:
 


Note the difference between the worn area indicated by the red arrow and the green arrow indicating the unworn area.
This would allow the axle to drop down causing the drum to be at an angle. This bearing plate should be replaced.

    Any of the factors mentioned in A, B, or C point to an alignment problem that needs to be addressed by following the drum alignment procedure.
D (not shown in the diagram) Examine the heating element. It should be properly shaped and parallel to the roast chambers outer wall- close to it, but not touching the wall. Also check for warping. If warped it must be replaced. The element should be parallel to the roasting chamber outer wall throughout its length. If necessary, check THIS PAGE for more details on how to align the heating element.
    If the element is warped, oddly bent, or twisted in such a way it cannot be aligned and it will need to be replaced. Contact Hottop to order a replacement heating element, and refer to THIS PAGE for the replacement procedure for your roaster.

INSERT THE DRUM
    Fully insert the drum into the machine by hand and be sure that the drive end of the axle fully engages into the drive coupling.
(1) When you do so, the axle should smoothly slide into the drive coupling. When fully inserted it should stop quite positively.
(2) That firm stop indicates that the drive pin in the drum's axle has seated completely into the drum motor's drive coupling and has stopped when the pin hits the far end of the slots in the drive coupling.
    Slide the drum out about four or five millimeters and slide it back in as few times. Each time it is pushed in it should should stop solidly and at the same depth each time.

REPLACE THE BEARING PLATE
    Refer to the following photo for this section:

    Proper bearing plate fitting is important for the life of the drum motor.
• When replacing the bearing plate, make sure the drum axle is properly located in the bearing plate's dimple.
• 1 - Insert the screws loosely to help hold the bearing plate in its place. Note how loose they are in the photo.
• 2 - Lightly hold the bearing plate aligned, ready to engage the alignment pins but do not push it into place. Just hold it against the drum with enough pressure to be sure the drum's axle is fully seated in the drive coupling, but do so without flexing the bearing plate.
• 3 - There should be no more than approximately 2 millimeters of clearance between the bearing plate and the bezel. If the clearance is excessive or insufficient the bearing plate needs to be adjusted.
  We are trying to establish the amount of pressure that the bearing plate will exert upon the axle. After assessing the need to make the adjustment, the easiest way to deal with that is to remove the drum the reinstall the bearing plate on the roaster.
  First place a straight edge across the face of the bearing plate to judge the tongue's position (the tongue is the "arm" of the bearing plate that holds the drum's axle). Bend the tongue inwards to increase force on the axle, or outwards to decrease the force as necessary. Use the straight edge once again to verify that the adjustment was sufficient. In most cases, one or twoo millimeters will likely be enough, on way or the other.

   It should now be quite easy to hold the bearing plate flush against bezel with minimal force with one hand while tightening the screws (as seen i the photo above). Tighten the four screws now but do not overdo the torque. The bearing plate is not under much actual stress and can easily stay in place with no more than having the screws very gently tightened.
    With the bearing plate screws tightened, reach a finger into the roaster right behind the bearing plate and apply upwards pressure to the axle. If the axle moves upwards more than a slight amount there is a problem. The bearing plate is not holding the end of the axle correctly. While holding the axle up attempt to push the tongue of the bearing plate towards the axle. If it moves the plate needs to be removed and the tongue bent inwards jut a little. If the problem cannot be resolved, replace the bearing plate.

DRUM CLEARANCE VERIFICATION
    Assemble the machine (install the drum and the bearing plate) but leave the front cover off.
(4) Examine the distance between the drum and the rear wall of the roast chamber. It should be around 1 millimeter and no more than about 1.5mm (it must be less than than 2 millimeters) from the rear wall of the roast chamber when that drum is fully inserted into the drive coupling (this is approximately 0.05"). Be aware that this measurement is critical. To describe this less specifically, it should be as reasonably close as possible to, but not touching the rear wall.
    A gap this small is difficult to see so we have a page on our website that guides you, step by step, on how to make a simple gap checking tool.


In this simplified illustration you can see the correct use of the tool.
    To use the tools you just made:
• Leave the front cover off during these adjustments.
• Remove the bean loading chute cover.
• Slide the "thicker" tool tool down into the chute and insert it into the roast chamber
• Slide the end of the tool upwards so that it is inserted between the drum and the rear wall of the roast chamber.
    It may take a bit of practice to get it into place. Looking into the roast chamber with a flashlight the first few times will help you find and "feel" the correct location. Once the tool is in place gently move it about and slide it up and down a few millimeters to get the feel of how to judge the gap. Now do the same with the "thinner" tool you made. Rotate the drum 1/4 turn and repeat the same checks. Repeat until a full revolution of the drum has been checked in that manner.

   Ideally, the thick tool should be somewhat difficult or impossible to slide in, but the thinner tool should fit just fine with little or no effort. If both of those conditions exist then the drum is in good alignment. If not:
  • If the thick tool fits too easily with excessive space left it means the drum is too far from the rear wall and you need to adjust the drum clearance.
  • If the thin tool cannot be inserted it means that the drum is too close to the rear wall and you need to adjust the drum clearance.

    DRUM CLEARANCE ADJUSTMENT
        If the drum is either too close or too far from the roast chamber's rear wall in the above positioning tests, the axle can be adjusted slightly following the Roasting Drum AXLE ADJUSTMENT instructions.
        If an adjustment was necessary and the drum is now properly located in the roast chamber, you may need to use the tools to recheck the spacing every two or three roasts for a while. This is because the heating and cooling cycles the roaster experiences may allow the metal to "relax" and cause the drum to return towards its original, incorrect alignment.

    THE GOLD KNOB
    (5) The Gold Knob should not have to be tightened more than just seated enough against the front cover to hold the front cover in place on the machine. That is the Gold Knob's only job. If there are still scraping noises then there is a problem that needs to be addressed. If the noise is from the front of the machine then try a tiny dab of food safe lubricant on the end of the axle where it is held in the dimple of the bearing plate. If scraping sounds are still heard, follow the Roasting Drum AXLE ADJUSTMENT again.

    TESTING
        Whenever a drum adjustment has been made you must run an "Empty Roast Test." That is a full roast cycle but do not add beans. Stay with the roaster throughout the roast, and if any scraping sounds are heard, immediately hit the eject button. Allow the roaster to cool and readjust the drum as necessary.

    If you are unable to adjust the drum, if scraping sounds are still heard, please contact Hottop USA.
    If we cannot solve the problem the machine will need to be returned to us for examination and repair.  

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