The Accidental Smallholder Forum

Smallholding => Equipment => Topic started by: arobwk on April 21, 2018, 02:32:26 am

Title: Mini Mantis Rotavator - I'm considering
Post by: arobwk on April 21, 2018, 02:32:26 am
I have chance of a 2nd-hand mini Mantis rotavator (basic garden model) at an attractive price.  Not expecting much of it, but I'm thinking could be handy for some light and tight inter-row weeding.
Any one own or used one?  What do/did you think please? 
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Scotsdumpy on April 21, 2018, 08:40:30 am
If it's cheap enough then buy it and try it. You can always sell on. I've toyed with the idea of getting one but my soil sets like concrete despite mulching and plenty of organic matter added so I haven't bothered. What's your soil like?
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Fleecewife on April 21, 2018, 09:26:27 am
They used to produce a 2 stroke version - avoid!  The 4 stroke is better but never let it run out of fuel, and drain it down if you're not using it for a while.  Our first two had to go back and be exchanged for new, third one died, current one with care is doing OK still.
They do work surprisingly deeply for their size.  I use ours for inter row weeding, loosening soil between potato rows for earthing up, and working extras into the soil where I'm planting out tomatoes etc in the tunnel, where a big machine is too awkward.
When it works it's great, when it doesn't, well, it doesn't.
For a second hand machine, check it over very carefully, and definitely don't buy it without trying it, including starting it yourself.  Also find out why it's being sold.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Jim Bob on April 21, 2018, 07:37:59 pm
Have just bought a mantis tiller 4 stroke. Haven’t fired it up yet.
Reading above post I am wondering why is it a problem if you let it run out of petrol. Why had it to be exchanged?
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Fleecewife on April 21, 2018, 10:17:28 pm
Thinking back it was probably the two stroke version.  When it ran out of fuel, the engine seized.  In the small print it did say not to let it run dry, so this was clearly something which happened frequently, and seems to be the reason they stopped producing the two stroke.  It was replaced straight away and without question, so their service is good.  I mentioned it because the OP said he is  looking at a second hand model, which could be a two stroke.
The second one went back because it had a starting problem.  After much discussion it turned out the diaphragm had a small hole in.  Having tried for ages to solve the problem, we were pretty fed up with me never being able to start it, and it failing to reach the revs it needs to turn the tines.  Our latest machine is kept in a cool shed, never left overnight in the tunnel which can get very hot and does something to the fuel.  It seems to be doing fine so far.  We used it today to chop composted manure into the potato rows before planting, and it buzzed away beautifully.  I think problems have arisen in the past because it's such a very tiny engine.
Good luck with your new Mantis Jim Bob.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Jim Bob on April 22, 2018, 09:22:30 am
Thanks for detailed reply. I bought the 4 stroke along with couple of extra attachments.
I ll test out and feedback here
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Fleecewife on April 22, 2018, 11:47:14 am
A bit more about the fuel problem and why you should keep your Mantis in an equable temperature.  Because of the high alcohol content of modern petrol, alcohol being hydroscopic, when atmospheric moisture is drawn into the carb as it cools, this makes a mixture which is highly corrosive to metal and plastic engine components and tubing etc.  So best to have either a full tank or an empty one when stored plus the equable temp.  Not sure I've explained this very well but: High alcohol + Water + Fuel = Corrosion
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on April 24, 2018, 05:31:15 pm
Ah! - the one I'm considering is the older 2-stroke model.  But I'm pondering, Fleecewife, why running out of fuel would seize the engine.  Reason for that not immediately apparent to me, but I will consult with a man who knows about such stuff.  Thanks kindly for the warning - I will keep in mind if I do eventually buy the little Mantis in question.

At the moment, seller advises (following my queries) that attempts to fire up his Mantis failed due to bunged-up carb' after storage.  He's ordered a new carb and will report back to me idc.  I'm thinking anyone would try to fire-up machine before advertising (and report the result !!!) so not a good sign, but I'll see how it actually runs eventually, on-site, before commiting to purchase. 

[Why doesn't everyone use "Fuel-fit" (other brands available) to help keep fuel in reasonable condition. I use it routinely and my machines have yet to refuse to start after winter storage.  They might be a bit hesitant to start, but they do start and continue to run fine over the new season.]

The kit I'm considering is hopefully £95 inc all available Mantis attachments.  Thinking might be worth a punt if it does run OK on inspection.  (I gasp when I consider the price of a new mini Mantis tiller!)

Scotsdumpy: my soil is fairly workable.  Reckon a low-power tiller will be OK for routine inter-row maintenance. 
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Fleecewife on April 27, 2018, 02:59:26 pm
<<< Ah! - the one I'm considering is the older 2-stroke model.  But I'm pondering, Fleecewife, why running out of fuel would seize the engine.  Reason for that not immediately apparent to me, but I will consult with a man who knows about such stuff. >>>

Sorry I didn't see this @arobwk

In a normal 2-stroke bike engine for example a Bantam, normal practice is to turn off the fuel  to let the carb empty and not leave residue when left standing.  However, because the fuel in the Mantis is so lean, and the tolerances (piston to bore) are so narrow, the loss of lubrication to the bore when the oil+petrol 2-stroke fuel runs out causes the instant seize.  This was a Mantis design flaw and, as I say, led to them dropping the 2-stroke production.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on April 27, 2018, 03:50:38 pm
Thanks Fleecewife for the explanation.  Having downloaded Mantis 2-stroke manual, I do note that a 50:1 fuel-mix is specified.  I believe they were using an engine from Echo so I shall go look for older Echo engine issues to see if anyone has any other thoughts on the matter.  However, seller not yet got back so not sure whether replacement carb' has transformed it into a runner worth further consideration (regardless of the potential no-fuel issue). 
 
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on May 07, 2018, 12:37:34 am
Well, the 2-stroke one I found has its new carb' fitted and, I'm advised, is running well. 
Have done much web research on the older Echo engine (used for many different power tools):  in the main, users rated it highly (albeit a bit noisy);  a few reported starting issues.  Try as I might, I could not find any other reports of seized cylinders.  So I'm going to take a chance and whisk it away on Tuesday (if I'm happy on inspection).  Agreed new price (after new carb') is now £115, but reckon still worth a punt especially as I'm getting aerator & dethatcher attachments in the price. (I previously said ALL attachments, which was poorly worded.)  I can always eBay the extra attachments if I don't find a use.
Despite finding some interesting stuff regarding the positive aspects of castor oil based 2-s oils, there are down-sides so I shall use a fully synthetic 2-s oil and maybe mix a tad richer than 50:1 and see how it goes (I'm bound to inadvertently run it to an empty tank at some time!).
I'll report again idc - good or bad.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: chrismahon on May 07, 2018, 07:11:37 am
Stihl now do a 50:1 oil designed for longer term storage of the mixed fuel. It's green as opposed to the standard red colour. I haven't tried it over a season yet, but I've always emptied the tanks on equipment anyway.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: cloddopper on May 10, 2018, 09:18:26 pm
Get hold of some syringes that you can accurately measure out small volumes of two stroke oil  and mark a plastic jug at the correct level to allow you to pour the correct amount of fuel in to make say a litre of correct solution of  2 stroke mix one at a time in a decent screw top container then add that correct measured volume of 2 stroke oil
 put the cap on the container &give it a good shake to give it  a good mixing .
  Now you have a small amount of correct two stroke mix in a clean container .

 Storing  large volumes of stroke even with fuel saver in it is not good as it does decay considerably . It will need a good shake every time it's ben stood for a week or more .    So long as the fuel tank top & cap  is free of dust & muck etc. when you fill it from the container everything should be hunky dory
  if you don't ensure great cleanliness when filling your heading for trouble with a blocked fuel fliter etc.  .

 Re running it dry / emptying it of fuel in the crb . I used to repair up to thirty to forty chainsaws , 2 stroke discutter's, strimmer's, hedge cutters & other small two stroke engined thingseach week 
 over th years I found that as the fuel in the carb evaporated it leaves a diluted film of 2 stroke oil in the carb that blocks drilling & /or causes the diaphragm or reed valves to stick closed as it dries out .
The corrosion already mentioned also starts to happen but it was usually the drying oil film in the carb that caused most of the problems .
Come spring I often had a hundred or more equipment's to sort out, nearly all with starting problems or partial sudden seizures a few minutes after the first start up of spring .

 Any machine that has stood for more than three months is best treated first before starting by removing the spark plug , giving it two one second squirts down the plug hole with WD 40 then  pull it over several times with the plug still out so that the cylinder walls are lubricated well ready for the initial starting .
 Put the plug back in , re fit the HT lead f fill with the right well mixed fuel mix and away you go
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on May 10, 2018, 10:48:28 pm
A fingers-crossed update on the old Mantis.  (Perhaps a bit early, but I'm so relieved right now!)
Started and ran pretty good on inspection & started just as well next day, BUT them bogged-down under load so tweaked high needle.  All seemed OK until I turned it off and tried to restart later.  Oh dear!  Two very frustrating days of inconsistant running and tweaking/re-tweaking followed by every component test known to man (except a compression test because it seems to have good compression and, besides which, I don't have the means to test that).  Eventually, after a final session with my father's assistance, it seems to want to run continuously and under load AND also restart when hot.
Eventual state of (interim) happiness was arrived at by tweaking low needle (with the odd tweak of Idle screw as well, but no tweak to High needle beyond the basic 1.25 turns) with the engine actually throttled-up slightly (via the throttle lever) over many minutes.  We eventually let off the throttle &, lo and behold, the engine was in happy mode!  Then, without that tad of throttle, a few v gentle, gradual tweaks to Low & Idle screws had her idling rather smoothly and also performing under load and restarting when hot. Sweet-spot revs for idling seem to be bit higher than specified 2,000 revs and there is the slightest rotation of the implement spindles presently, but enough is enough (for now).
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Fleecewife on May 10, 2018, 11:28:22 pm
I recognise that tale - Mr F has been there often - hopes up, hopes down.  I'm keeping my fingers crossed for you .


How did it perform for the actual rotavating ?  :garden:
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on May 10, 2018, 11:45:50 pm
Get hold of some syringes that you can accurately measure out small volumes ...

Yep, have those already from my farm store:  bought them (with large-bore needles) for herbicide injections, but useful, as you say, for fuel mixing and the odd tester injection of fuel into carb' (during recent Mantis tests).  The Mantis tiller seems happy enough with the 45:1 fuel-mix I used during her final recovery.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on May 10, 2018, 11:54:09 pm
I recognise that tale - Mr F has been there often - hopes up, hopes down.  I'm keeping my fingers crossed for you .


How did it perform for the actual rotavating ?  :garden:

Thank you, but can't report on rotavating performance (as of this eve) as my parents wouldn't have been too happy to see their lawns chewed up.  I took along the border-edger instead (unexpected, it came with that as well)- it performed well enough with that, but, of course, the real test will be in rotavator mode.  Weather permitting, that might be tested tomorrow.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on May 13, 2018, 09:43:19 am
How did it perform for the actual rotavating ?  :garden:

A bit like wrestling a lively wallaby tethered to a stick, on my stoney soil, but pretty good actually!  I'm quite impressed.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Fleecewife on May 13, 2018, 11:47:46 am
How did it perform for the actual rotavating ?  :garden:

A bit like wrestling a lively wallaby tethered to a stick, on my stoney soil, but pretty good actually!  I'm quite impressed.


 ;D ;D   Remember to pull backwards as you go forwards - stops it bouncing around and helps to dig in deeper
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: chrismahon on May 13, 2018, 12:53:13 pm
We have a mini Stihl rotorvator which I find is much easier to use if you walk backwards with it- contrary to the operating instructions.
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on May 13, 2018, 10:50:51 pm
I agree, as recommended, that actually pulling the Mantis backwards is the way to go.  The wallaby reference was a bit exagerated and, actually, once mastered and in weeding mode, I was often able to "hoe" a full circle around saplings in a single manouvre within inches of their lives - so far, none mangled! 
Haven't tested for digging planting holes yet - I'm thinking a good shovel or a wide auger bit might be easier/cleaner, but I shall experimemt idc when it comes to digging lots of holes for transplants.  (In passing;  some say augered planting holes hinder root growth into surrounding soil - not sure I'm entirely convinced about that - might do a little trial idc, i.e.  shovel v auger v Skippy and see whether any noticeable affect on plant growth + time and effort.)
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: Fleecewife on May 13, 2018, 11:13:42 pm
When we use the Mantis for preparing planting holes, it's to work in manure, seaweed meal etc.  It chops up less well composted material finely.  If it's to be a deep hole, it still has to be dug out by hand, but the soil is now very soft so lifts easily.  That is for veggies, not trees - they have nothing added so their roots spread into the new soil to find nutrients
Title: Re: Mini Mantis Rotavator - I'm considering
Post by: arobwk on April 27, 2019, 05:35:38 pm
... Haven't tested for digging planting holes yet - I'm thinking a good shovel or a wide auger bit might be easier/cleaner, but I shall experimemt idc when it comes to digging lots of holes for transplants. 

Verdict on Mantis v earth auger v shovel for digging multiple planting holes: 

Mantis - quite good where soil already loose/fairly weed-free and not too many other plants close-by (which will get covered by the spoil and also hinder recovery of spread soil back into the planting hole!)  Effort required to transport and restrain, while digging, is very bearable for quite a long while.  Unfortunately, Mantis not good for starting holes in the very weedy ground I've been tackling recently.  (Good for slimmers though:  actually, I should get the Mantis out having had a relatively sedentary winter when I also stopped smoking resulting in a bit more snacking and a bit more body girth!!)   

Single-person earth auger with 200mm auger bit - hard work "holding" auger while churning through well-established meadow grass.  Once through the turf it's OK with my soft soil, but the combined weight of power-head and a double-helix auger-bit takes its toll with the the lift-and-shift between multiple holes.  (Probably also good for slimmers, but likely to result in a new twisted body-shape after an acre or so  ??? :) )

Hand digging with a good, sharp shovel/spade - all will know this is always hard work!  But it's less stressful than either the auger or the Mantis.  However, it is just so boring (mentally) when digging tens and tens of holes at a go and I have 1000+ to dig overall.  (Obviously also good for slimmers!) 

Summary:  it's hard work no matter what option! 
However, I think I'm going to give the auger an extended/preferential trial hoping that I will regain the necessary upper body-strength in reasonable time to make it less onerous! 
In good, loose, open soil, I would be more tempted by the Mantis option despite the wider spread of the "diggings". 
Hand digging is eco, but I just can't stand the boredom, especially when digging solo.  (I was in such a foul mood recently after manual digging for 100x apple plantings.)