OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Four Stroke Lawn Mower Frames What is this Slasher? [Whirlwind]

I was leaning towards something brighter than brusnwick green I'll see what's available when the time comes.
The engine adapter plate has been completed engine fits well. Now I need to find some flat steel bar to make a blade bar.






On a off topic question for jack, I happen to be visiting Tasmania for my honeymoon in February. Any recommendations for some must see places?

Thanks Lorenz

Let me know on what colour you end with and where you get it. Brunswick green is definately too dark, ive been trying to match The Qualcast green for a while now. Meadow green is lighter again.

Hi Everyone been a long time since there has been any progress on my whirlwind slasher. With life being very busy the whirlwind has sat on a shelf in pieces for yeara. But with extra time off work due to corona I decided to get stuck in and finish her off.
A new blade bar was made as well as some new sheet metal for the frame. Also original pulley for the blade drive had been drilled by the previous owner so the pulley got replaced. I can proudly post some photos of the finished product pretty pleased with how it looks.
Just waiting on my whirlwind decal to finish it off.

That looks like whirling death on wheels Lorenz, I love it.

G'day folks,

This is what these machines originally used as blades. This one is branded 'Bamfords, Uttoxeter, England', who were a maker of hay machinery. Their Australian distributor was Mobilco Ltd, up to 1976.

G'day ,Lorenz ,Gadge + all,

Looks great Lorenz ,definitely worth all that effort to restore this Whirlwind slasher.

I was looking at that blade from Gadge and it's not reversible but both sides are sharpened and I was thinking the only way
you could make use of both cutting edges would be to put the V belt on so the direction of rotation is reversed.


Cheers
Max.

G'day Max, Gadge and all slasher lovers
Max, I think that's right.

These 'slasher mowers' followed the British tradition and
borrowed blades from agricultural machinery - the sickle bar jobs.
The North Americans didn't - adopting the bar blade.

The brochures seem to supply an answer - these blades were 'cheap'.
There is no reference to reversible blades that I can find.

Although on slasher mowers, it may have not made any difference at all.
High grass was still being cut and still falling over from the top of the blade.
The blade edge was just a couple of millimeter higher when reversed.

I do not feel sickle blades are the same as the fluted blades
we would see on more modern lawnmowers.

Cheers
------------------------
Jack

Hi Jack and all,

Thanks for that info Jack.,I just didn't think you can reverse blades "The blade edge was just a couple of millimeter higher when reversed"

I thought reversing a blade is a design no no ,the blades work like a boomerang creating an upward lift
if you reverse the blades the air flow will push the grass down making cutting more difficult..

But I see what you mean by the cutting of high grass the air flow may have minimal effect at pushing the grass down.
If there is no reference to reversible blades I think the air flow problem is why.

I think I did see one vintage American mower with this type of blade.

Cheers
Max

Hi Max and Gadge
Interesting topic this.

I think we need to look at sickle bar blades as closer to neutral lift in design.
Fluted blades tell a different story. The difference must be by degree (pardon pun).

But - for me - there is a catch or proviso ...

I would like to make one observation about the difference
between sickle blades used on a bar, as opposed to on a rotary disc.

This also goes to the difference between agricultural and
the horticultural. It appears to me that slasher mowers inhabit
a half-way house.

I have read that one of the 'draw backs' of sickle bar blades was clogging.
Clearly the angled blade edge played a big part in helping prevent this ...
on a bar blade with fixed 'fingers' and moving blades.

On a slasher - designed to slash (as opposed to manicure), I
have no doubt that some folks reversed them.

But why? My main argument goes to economy.

Rotaries killed the sickle-bar market in Australia simply because they
were much cheaper to maintain. And they were way less
likely to clog in adverse cutting conditions.

Sickle bar blades were made in huge volume to service the agriculture mowers.

I can really understand why some early slasher makers used these
triangular blades. They were dirt cheap in servicing a rotary ... as opposed
to the service demands of a sickle bar.

Cheers Max and Gadge!
Thanks for continuing to keep me honest.
----------------------------
Jack

G'day Jack and Gadge

Yes I find all the different blade designs interesting ,thanks for the blade info. Jack and Gadge.

" I think we need to look at sickle bar blades as closer to neutral lift in design."

I'm not sure on that Jack ,a lot of blade design specs that I have read say DO NOT grind bottom
of cutting edge. This will cause poor quality of cut and high horsepower requirement.

My understanding was if you grind the bottom edge of the blade instead of the top edge,
the blades can't lift the grass causing the base to clog with grass and stalling the engine
unless you have a larger more powerful engine.

Glad to be corrected on this if it's wrong it's just my understanding from the text I've read.

It would be an interesting test to sharpen the wrong side of the blade on a SupaSwift Big Bob mower.


The early forties Goodall slasher was the American slasher I was thinking of that used the same type of blade
as the Whirlwind.

Blade sharpening link click here

I saw a couple of YouTube clips showing the lift of the grass with standard blades and mulcher blades.

Another Interesting article I was reading was on self sharpening blades ,as the blades wear they sharpen by using
different types of steel in the blades ,the weaker metal wears away thus keeping a sharp edge.





Cheers
Max.

G'day Jack , Gadge and all,

I had a quick look to see what early American patents I had showing blades,one patent mentions a reversible
type of sickle blade but if you look at the image of the blade with the red circle ,the angles of the cutting
edges are reversed for each side of the single blade which allows you to install the blade on the other end of the
cutter bar with the correct cutting angle.



Cheers
Max.

Hi Max!
As always - great professional research there.
I totally agree that a blade intended for manicure in a horticultural
context would require a specific grind angle that produced lift.

Some-times I am such an idiot in how I say things.

I did mean to mean that 'neutral lift' related to the sickle bar context.
The speeds were way slower than rotational forces on rotating blades.

I also meant that in using slasher mowers to cut high grasses the lift may
be much less significant - maybe irrelevant.

However, you have made me think this through: -

The history of sickle usage for grass cutting
throws up an anomaly - Sickles and scythes were used early morning and
late afternoon when the grass [now cooler] would stand-up and be presented to
the blade. History tells us that the reel mower overcame this trait, to the relief
of country folk that complained about the noise created at these un-godly hours.

I do feel you must be right here: Any blade that can be sharpened
on one side will produce lift at high rotational speeds.

The early rotary - the Rotoscythe - had circular blades ground towards
the middle [a 'V'] that enabled the blades to be reversed - as in your patent.

For manicure in a horticultural context, blade design must be crucial.
I did want to distinguish between flat blades and fluted blades in
my original posting above. You have shown this must be a matter
of degree, and not the nonsense of 'zero lift' I spoke about in relation
to mowers intended to turn grass into lawn.

I have been reminded about the physics of tip speed with the
Bloodhound Project.



Max, many thanks for keeping me honest!

Cheers
------------------------
Jack

I found a gator blade in some junk.....
I want to attach it to a Pwer Torque or Lawn Beetle...
speedy

speedy,
I would have to ask WHY?

G'day Jack Speedy and Norm,

The Gator blades have an advantage over Victa blades if you want a mulcher blade, they will also last
a lot longer than Victa blades ,sometimes you may get a disadvantage by a lighter spinning mass.

Thanks Jack for the info. and the Bloodhound link ,I saw that last time it was posted on ODK,this time
I downloaded a copy of the video .

Yes as we know the sharpened edge on a flat blade can't be zero lift because the blades create enough air flow
to discharge the grass in a side discharge mower but not enough air flow to fill the catcher of a rear discharge
mower.

Also as we know to simply get over the problem of the Victa 18 blades being too thin to sharpen a leading edge
on the cutting side of the blades the problem is solved by bending new blades into a shape that would give
the back edge of the blade a higher stance of about 2.5 mm .(changing the pitch of the blades)

The Rotoscythe ,I did find a few pics but these blades don't look reversible, the earlier models may be
a lot different to the pics I have.

I was looking at the history of the Rotoscyth https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=69693
but are unsure if we have any images of the reversible blades.

Cheers
Max

The Gator blade is pretty heavy 16 inch, so not the Power Torque, maybe the Lawn Beetle .It was just an idea......
I really have more stuff to fix up before that experiment.
speedy

If anyone wants it, they can have it, just pay postage.
speedy

Hi all,

I see the ad for reversible blades.

Hmm looks like a round pizza cutter blade on the end of the blade holder that you turn to a new edge.


Cheers
Max.

Hi Max
This is a topic I'm glad you're researching.
I've never written a comprehensive record of blade design,
but its an interesting topic.

Yeah, I did stuff up on the Rotoscythe design comments I made.
The circular blades could be rotated, but not reversed.

What I find fascinating and historically important is that David Cockburn
understood angle of attack and the aerodynamics needed for lift
and to catch grass.

If the small circular blades created bugger-all lift, the bladeholder
most certainly did. Your images of the bladeholder are not good
examples; in that the changes are an abomination of the design.

[Your patent images are close to production models].

The thing is that Rotoscythe had an advanced rear catcher mower,
with a high arch in the inter-war years. Pope looked at aerodynamic
bladeholders in the late 1950s, and Victa for high arch discharge a
decade later with their VCs. They would seriously look at bladeholder
aerodynamics with the CSIRO collaboration after that.

The gallery below shows another abomination of the design, an
original blade holder, and a parts list confirming this.

Many thanks for your great research.
It is appreciated by all.

---------------------------
Jack

G'day Jack,

Great images of the blades, you can defiantly clearly see the cutters in the pics ,the cutters
remind me of pipe cutter blades ,I wonder in these cutters are of high quality steel like
pipe cutter blades.

Thanks for the Rotoscythe pics and info, yes the adulterated Rotoscythe bladeholder images are
not great examples but I could see the steep angle on those bladeholders showing a fair amount
of lift.

Yes the Rotoscythe patent explains a lot,like why the rear discharge mowers require a slightly larger ground clearance
at the back of the mower when cutting long grass ,it's to avoid clogging of the cutters by the grass.

The patent mentions when cutting a fine lawn you are better off having the cutter plate parallel with
the ground.

The Victa 18 blades I showed previously ,I should mention those blades are factory made and are factory press
shaped blades so I did not want anyone trying to make those blades , as you can fracture or crack the Victa blades
by bending them,if you weaken the integrity of the steel you could possibly kill someone by the blades
breaking off .

The interesting thing about the Victa 18 discharge blades I previously posted they show an example of reversible blades,
it's impossible to fit these blase the wrong way up just like the completely flat Victa 18 blades.

I would say it's definitely an advantage to have some lift by the blades when cutting long grass with a rotary slasher
or mower so that the grass can be discharged away from the blades which stops the blades clogging with grass and also prevents
the engine stalling.

As a preteenager I learnt about leading and a trailing edges when making home made boomerangs out of plywood packing crates.
If you get those leading and trailing edges wrong it makes a huge difference.

I saw one patent which had an addition to the cutter assembly, to stop long grass ,vines ,etc from wrapping around the
cutters and cutter bar shaft .

Patent with a line trimmer from the fifties.

Definitely interesting all the different blade designs and conversation .

Cheers
Max.