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  1. #1
    TomPracMac is offline Aluminum
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    Hi,

    Help, please. What is the proper direction the drums should rotate on a 25" Kuster Ultasand dual drum sander.

    I acquired this sander from an estate, and therefore it's impossible to talk with anybody who has ever operated it. Further, the only owner's manuals I've been able to locate do not provide any indication of proper rotation direction.

    At present, the drums rotate 'away' from the operator. That is, unless the board is very securely held by the traveling feed belt and pressure bars, the drums would grab the board and shoot it through the sander away from the operator. [Sort of similar to climb milling....]

    The drum rotation on this Kuster sander is the opposite of my Delta 18" /36" drum sander [and it's is the opposite way wood planers rotate]. That is, my Delta sander and planers tend to reject the board back to the operator.

    Sometime, a prior owner modified the machine to make each drum individually adjustable for height. I am concerned that he/she changed the drum direction also. Anybody know which way the drums should rotate? [I'm a little too scared to try ... fearing the drums are now going the wrong way.]

    Thank you very much for the help. Tom

  2. #2
    stephen thomas is offline Diamond
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    Tom, I don't know the specifics of Kuster (weren't they a kit or something?) But all the drum sanders I've seen, as well as wide belt sanders, oppose the direction of feed of the board. There is no reason to have climb cutting with a sander, and a lot of good reasons not to. If it's 3 phase and you are using a convertor, it is pretty common to find that motors turn the opposite way from where they were last used. If it is Single phase, maybe someone wired the motor up using the diagram, without thinking which way it would turn, and never got around to changing it or using the machine?

    smt

  3. #3
    gmatov is online now Diamond
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    That would be a bitch, wouldn't it?

    To put in a 2 X 12 X 10 foot plank, have the sum'bitch go through your wall, and mebbe anybody standing there to catch the outfeed.

    The feed rolls or the feed belt force the wood under the drum, the drum and the abrasive, at the bottom, are rotating toward you resisting the material.

    As you say, your planer cuts toward you, the sander must, also.

    If you have a 3 phase motor, switch any two of the three wires, you will reverse the direction, if it is single phase, check the nameplate or whatever for wiring schematic.

    Cheers,

    George

  4. #4
    gmatov is online now Diamond
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    BTW,I am assuming it was operating on 3 phase at the original shop, and on 3 phase at YOUR shop. Again, their shop had the phases different than your shop does.

  5. #5
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    crzypete is offline Hot Rolled
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    When I was rebuilding my widebelt sander- a 12" AEM. (pics here http://machinejunkie.com/forum/viewtopic.php?t=328 ) I found that for wood they are supposed to feed like a planer into the work- like everyone is saying, but when set up for metal graining they should rotate the opposite direction essentially traveling with the work.

    I do not know if this is the same for a drum sander, or even if you could run metal through a drum sander.

    Pete

  6. #6
    stephen thomas is offline Diamond
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    crzy- can you elucidate on this? I used to run an 36" AEM (in someone elses plant) doing metal and it opposed the cut, just like a wood planer or sander. For appearance graining, don't they run the head slower and use something like a scotch-brite belt?

    Whether it worked better or not, I'd be scared witless of liability, to have someone on off-feed, with it fed "climb cutting". The parts we fed were all boomerang shaped shelf brackets of all sizes for grocery store shelving. A loose one would probably decapitate someone. That thing munched belts anyway when careless help put bent stock in.
    I should clarify, that in our case, the abrasive finish was for light deburr from stamping, & smooth & tooth for powder coat, not appearance itself. Although I think we did grain stainless in it on a rare ocasion.

    George, I was trying to tell him the same thing, about the phases being different from the last installation, if 3ph. You probably stated it more clearly.

    smt

  7. #7
    Doug is offline Diamond
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    "George, I was trying to tell him the same thing, about the phases being different from the last installation, if 3ph. You probably stated it more clearly."

    Wouldn't the feed belt also go the wrong way if the phasing was incorrect?

    Maybe it was used for graining metal, in my experience the heads run the opposite rotation of wood sanders.

  8. #8
    TomPracMac is offline Aluminum
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    I thank all of you for sharing your knowledge and tips ... about the drum direction.

    A couple of quick additions to my original post:

    #1. The drums are driven by a single phase, 5 HP, 220V motor.

    #2. It has a separate motor to drive the conveyor/feed belt.

    I'll reverse the motor before trying it.
    [If I abolutely had to test it in its current configuration, I'd make certain that the space shuttle and similar aero vehicles are not in the general area !!]

    Tom

  9. #9
    stephen thomas is offline Diamond
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    Hmmmm...come to think of it (since I'm running it today) my RAMCO widebelt conveyor has a drum switch and will feed either direction. Maybe someday when I'm feeling brave and there is nothing between that side & the cement block wall.....

    You metal graining guys going to clarify what is used for abrasive?

    smt

  10. #10
    Frank_Dorion is offline Aluminum
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    Tom,

    Most of the comments received so far on your post sound intuitively correct, and, lacking other information, I would probably agree with them. However, I happen to have a Kuster double drum sander, the 18" version that is probably very similar to yours (5HP drive motor, etc.). I was also lucky enough to get the manual for it when I bought it, so I checked for information on direction of rotation for the drums. It turns out that the correct rotation is a "climb milling" set up. Here's a quote from the manual:

    "Check drum rotation and the movement of the conveyor belt. If looked at from the infeed-left side of the machine (the side with the drive belts and pulleys closest to you), the drums will turn CLOCKWISE. The conveyor belt runs from front to back. Please note that the cutting action of the Ultrasand runs opposite to that of most planers - experience ant testing have shown that this set-up yields the best results."

    Tom, if you need any further information from the manual, send me an email with your contact information. - Frank

  11. #11
    gmatov is online now Diamond
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    SMT,

    Sorry, I did not even see your post.

    Per Frank_Dorion "
    "Check drum rotation and the movement of the conveyor belt. If looked at from the infeed-left side of the machine (the side with the drive belts and pulleys closest to you), the drums will turn CLOCKWISE. The conveyor belt runs from front to back. Please note that the cutting action of the Ultrasand runs opposite to that of most planers - experience ant testing have shown that this set-up yields the best results."

    I'd like to see this picture to see just what they call the "infeed-left side".

    The only logical way to make a sander like this would be to have it sand against the feed. Force the work against the drum's direction of rotation.

    Elsewise, if it actually DOES "climb mill", the infeed and outfeed rolls have to be able to control the motion. And have to be adjustable to provide enough braking to keep the work in the machine till it is done having work done on it.

    Sumpin ain't right, I don't think, with that method of operation.

    Cheers,

    George

  12. #12
    stephen thomas is offline Diamond
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    Well you learn new stuff every day! And once again, just goes to show it is best to get it from the source, since common experience may be incorrect for a given machine. Thanks, Frank.
    One of the factors for appearance in sanded work is the "scratch" length. Climb cutting would promote a longer scratch length. When I have time, i may just play around with some wood fed "backwards", since as related, my Ramco will feed either way.

    Will the Kuster do abrasive planing? or is it mostly a finishing machine? Is the roll padded or hard? What kind of DOC is recommended for, say, 80 grit or 60 grit at what conveyor feed speed?

    smt

  13. #13
    Frank_Dorion is offline Aluminum
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    George - Yup, the pressure feed rolls are what keep the workpiece from being ejected out the back of the machine. Here's another quote from the Kuster manual:

    "DANGER! Due to the torque and the speed with which the drums turn, if you attempt to take off too much material in a single pass (more than 1/32" with 36 grit, less with finer abrasives), it is possible for a thin, light piece of wood to shoot out of the outfeed end, propelled by the sanding drums. [This is most likely to happen if the pressure rollers are improperly adjusted.] Stand off to the side when taking up work from the outfeed end and make sure that the area in line with the outfeed end is clear."

    Stephen - I would call the Kuster Ultrasand something between a finishing machine and an abrasive planer. You can judge it for yourself based on the depth of cut recommendation mentioned in the above quote for 36 grit. For finer grits, recommended depth of cut is about .010" per pass. Mine is a double drum machine and the drums are hard. However, the manual describes how to pad the drums with felt wrappers if desired. Conveyor feed is via a gearmotor and chain drive, so conveyor speed is fixed on this machine. The two sanding drums are 6" diameter and there are 3 pressure feed rollers.

    Frank

  14. #14
    crzypete's Avatar
    crzypete is offline Hot Rolled
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    SMT,
    My metal sanding information comes from my recollection of a call to timesavers back when I was rebuilding my machine. It turns out that a friend had a very similar machine to mine which he was using for wood, but it had been set up for metal- the giveaway was the dust port on the back of the machine rather than the front. He reversed his machine and is getting better results for wood with the standard cut.

    I have no knowledge of the metal sanding setup in terms of paper or non-woven abrasive. I would be curious to learn more about sanding metal, it could be beneficial to my work.

    Pete

  15. #15
    TomPracMac is offline Aluminum
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    1. Thank You to all who contributed, especially to Frank_Dorion. He provided exactly the infotmations needed, and as he pointed out, the correct drum rotation seems to be counter-intuitive.
    Thank you, Frank.

    2. When I start using the Kuster sander, I'll begin with a very light depth-of-cut, ... and do some experimenting from there. Since I'll be using it most of the time as a light-duty abrasive planer, I'll try running the drums both directions. Hopefully, I can get to the point where the machine will safely remove more than .010" per pass.

    Once again, thanks. You bailed me out.
    Tom

  16. #16
    stephen thomas is offline Diamond
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    Frank,
    Thanks. The Kuster sounds like a very competent machine. My interpretation of finishing vs abrasive planing has to do with the hardness of the rolls. Generally for a machine to do planing (uniformly calibrated work) the contact roll needs to be hard. Sometimes even metal, in widebelt sanders used primarily for calibrating panels, say for veneering.

    Of course a widebelt allows the opportunity to provide for a platen. So a hard roll can be used for planing/calibrating, and the platen dropped into contact for smoothing. The surface of the platen is soft so it allows conformance of the abrasive with the given surface, and promotes a long scratch pattern (compared to the roll).

    Now that it has been explained as correct, I'm suspecting that the "reverse" feeding on the Kuster drum is one method of increasing the scratch length, and hence the perceived "quality" of finish.

    As far as amount of stock removed, there is pretty much an incontrovertible relationship among drum speed (abrasive sfm), abrasive grit, and table feed (work fpm). This varies for wood species. Essentially, for a given grit at a given abrasive sfm in a given wood; one can trade DOC against table feed, but there will be a product of the 2 which is impossible to exceed practically without glazing the work, burning & clogging the belts, both, or destroying the belt. Double the DOC, and the table feed will need to be halved. Double the feed speed, and the DOC will need to be halved.

    There are published tables for the values. I keep an abridged table taped to the side of my sander for reference. Staying in the limits is one of the best resources for promoting both better work efficiently, and longer belt life.

    Thanks!

    smt

  17. #17
    stephen thomas is offline Diamond
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    Had some time tonight to look this up. As mentioned, the rate varies depending on the wood. The same grit in softer wood can stand a heavier cut. However, it is not necessarily intuitive. Some soft woods like cherry or walnut need a slightly reduced load. Partly due to the resin content and propensity to burn. The load also might need to be reduced for dense hard exotics. And all bets are off for ridiculously resinous woods like bloodwood.

    For your middle of the road domestic woods like oak, ash, hard maple, hickory, hard particle board, a good limit to the question "what is the maximum stock that can be removed by a given grit" is as follows. The assumption is that the machine builder has optimized the abrasive SFM for the roll diameter employed, and that the design is for wood. The following also assumes a "hard" roll, say 90duro or better. A platen (or a padded contact roll in a drum sander) would reduce values about 1/2.

    at 20fpm conveyor feed speed, 36gr can take .186" DOC, 40gr. .094DOC, 50gr. .062DOC, 60gr. .043DOC, 80gr. .037DOC, 100gr. .025DOC, 120gr. .018DOC. 150gr. .011DOC, 180gr. .006DOC, 220gr. .003DOC

    The values are geometric and they do tend to be high limits. If your conveyor runs at 25fpm, multiply the DOC by 20/25 (reduce depth by 20%), etc.

    For stock reduction, it is generally better to run the conveyor at a moderate pace (more slowly) and let the abrasive work without clogging. Running faster for polishing the work at very slight cut depths might work in some cases by increasing the scratch length, but the finer abrasives (180 - 220)can barely stand a cut much over .001" at conveyor feeds over 35fpm.

    Notice that machine HP is not a factor in the DOC limit. DOC is feed/abrasive limited. HP matters only to the extent that the abrasive capability can be utilized at the typical widths sanded.

    I have found the figures to be quite accurate and useful. Combined with a scratch depth chart, going "by the numbers" promotes efficient work and is conservative of abrasive consumption and machine wear.

    smt

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