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  1. #1
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    Making progress - Plate compactor

    Got a plate compactor for the weekend to go along with the backhoe. I've been a dig'n maniac!

    Those who have been following this project know I started out thinking I needed to modify my soil. As I have learned, I just need to control the moisture in it, it's clay. With the right amount of moisture it is perfect. To little, and it turns to powder; too much and it turns into the blob from hell. If it's dry and I dig with the backhoe, the soil breaks into what looks like rocks. If it's dry enough, I can pound it to powder with the compactor, then IF I can get water to it, water it down, and it's perfect. If there is a bit more moisture I still get pseudo-rocks, but they don't break apart under the compactor and act more like chunks rubber. Some places the moisture is perfect and the compactor turns it to pavement. (Can't believe I'm happy about that lol) Some places, the moisture is too high and the compactor just stops dead and is near impossible to move.

    Working to get water available and controllable. As I go, I'm gaining support, so I'm hopeful about that. Have a plan in the back of my mind for a track-wide watering system tied to the City and School's irrigation systems but something I can control/tweak.

    So, why does a plate compactor have a cut-off when it's tilted? I jumpered it, but I'm puzzled what the concern is. Anyone know?

    Favorite brands of plate compactors?

    Who here wears a seat-belt when operating a backhoe/TLB? Seems like that eliminates one of the most likely to succeed escapes to a roll-over. Am I being naive?

    How do you deal with grass clods? I don't know what it is, but it's tough stuff that survives in the desert; runners and such. Really messing with my mojo here. The only solution I have come up with is picking them up one by one and beating the dirt out of them.

    Damn, going uphill is work!
    Making progress - Plate compactor-07-plate-compactor.jpg

    Roughed out
    Making progress - Plate compactor-03-after-compactor.jpg

    Making progress - Plate compactor-04-before-compactor.jpg


    Compacted

    Making progress - Plate compactor-06-after-compactor.jpg

    Making progress - Plate compactor-05.jpg

    Making progress - Plate compactor-08.jpg
    Last edited by ki5ka; 1 Week Ago at 05:06 AM.

  2. #2
    Single(Pivot)and Happy
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    SDMBA has a Harbor Freight plate compactor that has been 100% reliable for at least 5+ years. I think we paid $450-$500 for it new.

    As you have found out the key to successful and efficient compacting is soil moisture content and soil composition. If either is to far off from ideal, and you cannot for whatever reasons amend the situation, any compactor will not provide a quality finished tread surface.

    I tip my hat to you fellow builder. Nice work.

    Oh, I have been told the tipping cutoff is due to oil, or lack of oil, being able to provide proper lubrication to all parts of the engine.
    The suspension of your bike sucks if it's different than mine. Really. It sucks. Big time.

  3. #3
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    Thanks Boulder

  4. #4
    FatBike Fiend
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    Ki5ka asked: "So, why does a plate compactor have a cut-off when it's tilted? I jumpered it, but I'm puzzled what the concern is. Anyone know?"


    Most have them are equipped with small 4-stroke Honda or Koehler engines which don't have real oil pumps. Instead they have little flapper impellers in the crank case which simply splashes oil around inside and lubes all the bits and pieces. If you tilt the unit to the point where the impeller is above the oil level, presto, no more lubrication.

  5. #5
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    Ki5ka,

    As others have said, soil compaction is highly dependent on soil moisture. Too far above or below the optimum soil moisture, and you are just wasting your time trying to get good compaction. It's a fact of life that in many places and soil types you have a very narrow window of conditions where your soil will be in the optimum moisture range, and more often than not you don't have a water source handy to fix the issue. Thankfully, in your situation, you may have access to a hose or a sprinkler.

    I'm not a real big fan of vibratory plate compactors for trail building, as I've seen them misused as window dressing on a machine built trail more often than not.

    A plate compactor is useful in a fairly narrow range of conditions. If you're compacting a thin layer granular soils (say 3/4" minus crushed rock) they work great. But they don't do a lot of good on fine grained soils (silt/clay).

    A walk behind plate compactor doesn't have enough weight for the surface area of the plate to provide much compaction effort. It relies on the vibration to do the job.
    The idea behind using vibration for compaction is that all the angular shapes soil particles (sands/gravels) are vibrated and re-aligned so all those irregular shapes fit tighter together and take up the void space.

    But, that vibration doesn't work well on cohesive soils (say >50% silt/clay content), so all you end up with is a "pretty" smooth surface on top couple inches with un-compacted soil beneath that won't hold up.

    The other issue I often see is trying to compact layers that are far too thick. If you're building a 3 ft tall berm, and you start with a 3 ft tall pile of loose soil, you're not going to end up with a 3ft tall berm. I've seen a lot of builders try to fix that by starting with a 4 ft tall pile of loose soil and compact the crap out of the top 6-12 inches. End result is a 3ft tall berm that is going to shrink down to 2.5 ft or less after you get traffic on it, and a couple seasons of natural settlement.

    In the engineering/construction world, you will often see engineering specifications for fill/backfill that call for a maximum loose layer (lift) thickness between 6 and 12 inches. You compact one layer, then add another loose lift and compact that and so forth. While the need for good compaction on a trail doesn't rise to the level needed to support a building foundation or an interstate highway, the concept still has value.

    When you're building features out of dirt, whether by hand or with a mini-ex (or backhoe) you still need to compact your soil in thin layers, and since you can't drag heavy construction equipment out onto a trail to compact your soil, you have to adjust your loose soil layer thickness down to about 3-4 inches if building by hand, or maybe max of 6 inches on a machine build.

    On a machine build, you can tamp each layer with the excavator bucket, then do the finish work by hand. On a hand build, you can compact your layers with a hand tamper, a flat shovel, and even feet. The dirt jump guys have really perfected the art of compacting/shaping dirt with little more than a flat shovel and a hose or watering pail.

    I don't want to completely discourage you from you using the plate compactor as it can still be useful as long as you understand the limitations.

    All that said, your biggest challenge is still the moisture content. If you've got access to a hose, you can try wetting the soil first, but you really need to get the moisture mixed deeply into the soil. Too much on the surface, and you may end up with a sticky unworkable mess.

    One thing you may want to try is to wet down the areas you plan on compacting, let it soak in overnight, then try compacting it the next day before the top layers dry out too much.

    The last note on compaction is that mountain bike tires work really well at compacting soil under the right moisture conditions, so at a certain point, once you've done all you can do with a the backhoe, flat shovel or plate compactor, the best way forward is getting tires on the dirt.
    No dig no whine

  6. #6
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    Thanks for the reply TWD

    Quote Originally Posted by twd953 View Post
    ...Thankfully, in your situation, you may have access to a hose or a sprinkler.
    Yes, I can see that is going to be crucial

    A plate compactor is useful in a fairly narrow range of conditions. If you're compacting a thin layer granular soils (say 3/4" minus crushed rock) they work great. But they don't do a lot of good on fine grained soils (silt/clay).
    I don't think I'm really using it as intended. I'm using it primarily to bust up chunks of dried clay/caliche. If the moisture is just so, it turns to powder, which I can easily shape, then add moisture back into (where I have it available).

    All that said, your biggest challenge is still the moisture content.
    I think so too. I need water during construction but I also need to come up with an irrigation scheme to keep a level of moisture in the clay once the trail is built. I have several berms that I built by hand that have been ridden for about a year now with no attention at all. They get just the right amount of water from the field watering system. As yet, I don't have control or access to the school's or the city's. Working on that. Support continues to grow, and the district admin has stepped up in several remarkable ways, like giving me the backhoe to use! ... so it might not be out of the question.

    The last note on compaction is that mountain bike tires work really well at compacting soil ...
    I have discovered that! It is amazing how a roughed out section of trail that I initially can't ride, is easily rideable after 10 kids ride it for about 15 minutes.

  7. #7
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    Quote Originally Posted by Wildfire View Post
    If you tilt the unit to the point where the impeller is above the oil level, presto, no more lubrication.
    So... this sounds like a legit concern. Sounds like really dumb engineering LOL

  8. #8
    FatBike Fiend
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    I know, right? For some reason I don't think the engineers were thinking about mountain bike berms when they designed these things. The usual construction application is for compacting nice flat gravel pads for driveways and slabs, how boring.

  9. #9
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    So is there another affordable option? What about those jackhammer look'n things?

  10. #10
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  11. #11
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    Unfortunately "Jumping Jacks" have the same issue regarding engine lubrication and they are just not designed to work at steep angles. Trying to hold one at a steep angle would wear out the burliest among us in no time. You can rent or buy a plate compactor attachment for an excavator boom (or possibly your backhoe if it has the hydraulics for it) that runs off the aux port of the machine's hydraulics that might be better for compacting and shaping berms -- although I haven't tried that yet... maybe someone else can chime in. I've had pretty good success just using the bottom surface of an excavator bucket "patty-cake style" to tamp berms and backslopes.

  12. #12
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    Quote Originally Posted by Wildfire View Post
    I've had pretty good success just using the bottom surface of an excavator bucket "patty-cake style" to tamp berms and backslopes.
    That's a great idea, I'll have to add that to my repertoire of moves to practice.

  13. #13
    WillWorkForTrail
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    Seat belts: if the machine has a ROPS use the seat belt and keep your arms and legs inside the ride at all times. If not, skip the belt and jump off the high side. Also, switch the machine off before/as it goes over to save the engine.

  14. #14
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    Quote Originally Posted by ki5ka View Post
    I don't think I'm really using it as intended. I'm using it primarily to bust up chunks of dried clay/caliche. If the moisture is just so, it turns to powder, which I can easily shape, then add moisture back into (where I have it available).
    Hey, use it for whatever works! If it's busting up those big chunks and making them workable, then it is far better than trying to bust those up by hand.
    No dig no whine

  15. #15
    Dirt Monkey
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    On the irrigation issue, look into soaker hoses for gardens. Might be able to place them them in/on the berms to supply water. Berms will breakdown overtime regardless how well they are compacted from the shearing forces of tires on the dirt. Keeping moisture in the dirt will combat this.

  16. #16
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    Quote Originally Posted by aero901 View Post
    On the irrigation issue, look into soaker hoses for gardens. Might be able to place them them in/on the berms to supply water. Berms will breakdown overtime regardless how well they are compacted from the shearing forces of tires on the dirt. Keeping moisture in the dirt will combat this.
    I had been thinking along those lines.

  17. #17
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    Quote Originally Posted by Wildfire View Post
    ...I've had pretty good success just using the bottom surface of an excavator bucket "patty-cake style" to tamp berms and backslopes.
    Thanks for the idea Wildfire, I tried it out last night and it worked great. Also does a decent job of breaking up the clods, though not as fine as the compactor, it works well on the big ones.

  18. #18
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    Quote Originally Posted by ki5ka View Post
    Thanks for the idea Wildfire, I tried it out last night and it worked great. Also does a decent job of breaking up the clods, though not as fine as the compactor, it works well on the big ones.

    You're welcome, ki5ka, it takes some finesse and practice keeping the bottom of the bucket parallel with the berm surface. Keep it up and you'll be sculpting berms like Michelangelo in no time. Also keep all those pivots greased on your arm and bucket, all that banging around tends to wear equipment bushings out rather quickly. If you really want to get fancy, try to get ahold of a grading/finish bucket with no teeth or you can fabricate a finishing edge attachment that clamps to your existing bucket.

  19. #19
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    Quote Originally Posted by Cotharyus View Post
    Seat belts: if the machine has a ROPS use the seat belt and keep your arms and legs inside the ride at all times. If not, skip the belt and jump off the high side. Also, switch the machine off before/as it goes over to save the engine.
    Thanks Drew. Can't imagine having the wherewithal to turn the machine off! Sounds like you have had the experience? Seems I replied to this already but don't see it so I probably typed it but never posted. If it's a repeat... sorry.
    Last edited by ki5ka; 1 Week Ago at 05:19 AM.

  20. #20
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    Quote Originally Posted by Wildfire View Post
    You're welcome, ki5ka, it takes some finesse and practice keeping the bottom of the bucket parallel with the berm surface.
    Did some more today and I'm getting better at it. Also getting 3 inputs at once. Just when I start feeling confident it all goes to hell, but it's coming along. Doesn't hurt that I'm getting time in just about every day, even if just for 40 minutes.
    Also keep all those pivots greased
    Yeah, I was wondering about that. I saw the "every 10 hours" sticker and wondered if that was like Fox's fork service interval, or if that was really something worth doing.

    If you really want to get fancy, try to get ahold of a grading/finish bucket with no teeth or you can fabricate a finishing edge attachment that clamps to your existing bucket.
    That sounds interesting! I'll have to see about that. I've got some steel laying around

  21. #21
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    Quote Originally Posted by ki5ka View Post
    Thanks Drew. Can't imagine having the wherewithal to turn the machine off! Sounds like you have had the experience? Seems I replied to this already but don't see it so I probably typed it but never posted. If it's a repeat... sorry.
    Actually, I don't have any first hand experience turning a machine over. But I've been in situations where turning a machine over seemed like it was at even odds with getting through unscathed, and I've put some real thought into the situation, as well as talked to a lot of friends with first hand experience. I was on a job last summer where a friend laid a mini-ex over on a very non-sketchy section of trail - his dog was on the machine with him and bumped the foot control back - backed him into a drainage he'd just dug at just the right angle to turn the machine over. He and the dog were fine. He wasn't quite fast enough on the ignition though because he was putting a hand on the dog to ensure it didn't end up under the machine, and had to put a new head gasket on the machine. Another friend of mine slid a Sutter of the edge of a trail just last week. It didn't turn over, but he had to use the Sutter's winch on one end, and a griphoist on the other to work it back up onto the trail.

  22. #22
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    Quote Originally Posted by Cotharyus View Post
    Actually, I don't have any first hand experience turning a machine over. But I've been in situations where turning a machine over seemed like it was at even odds with getting through unscathed,
    Just had one of those sketchy moments yesterday. Going straight up the berm that surrounds the field and the front end started rising when I accelerated a bit roughly. I stopped, then started backing down and when I touched the brakes, the front end came up again. Got to the bottom upright, then put on the seatbelt. I pivoted the bucket forward and was able to drive up it ok, as long as I didn't touch the throttle. Thinking about it now, I'm wondering why I didn't back up.

  23. #23
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    RE low-oil cut-off function; almost all good quality small engines (and their clones) have them. Most small engines up to 10 hp are splash lubricated. Your grandfather's Briggs and Stratton rototiller was that way and they never had low-oil cutoff's until Japanese engines began to put them to shame.

    Some machines actually do have "tilt" switches but not likely at the HF level.

    Usually not a matter of "jumpering" the switch but just unplugging it. YMMV.

    Another way of dealing with it is to keep the device positioned so the low-oil switch is always on the downhill side.
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  24. #24
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    Quote Originally Posted by Moe Ped View Post
    RE low-oil cut-off function; almost all good quality small engines (and their clones) have them. Most small engines up to 10 hp are splash lubricated. Your grandfather's Briggs and Stratton rototiller was that way and they never had low-oil cutoff's until Japanese engines began to put them to shame.

    Some machines actually do have "tilt" switches but not likely at the HF level.

    Usually not a matter of "jumpering" the switch but just unplugging it. YMMV.

    Another way of dealing with it is to keep the device positioned so the low-oil switch is always on the downhill side.
    The other reason for tilt switches is to keep from sucking oil into the cylinder head if you tip the unit over. Vapor lock or an oily spark plug mean the engine won’t run.

  25. #25
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    Trying out the soaker hose idea. This is the only sandy section but I think there is clay powder mixed in. Guess I should do an analysis and see. Curious to see how it will be with moisture.
    Making progress - Plate compactor-soaker-hose.jpg
    It's not obvious in the pic but this is about a 4 foot berm.

    Casual perk test was pretty much unchanged after 15 minutes.
    Making progress - Plate compactor-perc-test.jpg

  26. #26
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    Worked GREAT! Left it on overnight at a trickle. This morning the whole top half has the perfect amount of moisture. Raked it out then tamped it. Rode it at practice after school and couldn't be happier. I'm curious to see if I will need to keep moisture in it, or if it will remain hard when dried out, after tamping it.

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