Sharpening a cylinder mower - hows it done?

[stig]

Thought i'd ask you knowledgable lot first.... Its probaly been mentioned before somewhere

Traditionally i've used a file and gauged the amount being removed by the cutter bar...not entirely accurate but it ultimately cuts the grass

Anyone any idea how the pro's do it and if it could be replicated easily at home. i own a Harrison L5 lather so could remove and spin the cylinder between centres. i thought of making a traversing angle grinder holder but need ideas/inspiration

[hermetic]

It is done on a very simple lathe like machine with a tool post grinder. The cylinder is removed from the mower, fitted into the lathe, and rotates as the grindstone traverses along the bed. This grinds all the blades and also makes the cylinder perfectly circular. There is also a fitting on the lathe which takes the knife from the bottom of the mower and puts a perfect square edge on that as well. The mower is then reassembled and adjusted/ tested, each blade at a time, till it will cut a single sheet of newspaper all across the length of the knife.
Thats how I was shown it anyroadup!
Phil.

[John Rudd]

Yup seen it, experienced it first hand at work....
Tp grinder with cylinder blade assy between centres....
Good luck with it.....

[krv3000]

hi well ther is a nuther way leev the blade on the cutter and ajust the blade hight keeping it even then use valve grinding past put sum on one blade full lenthe then run the cuter do this to all of the blades and you will av it nice and sharp in no time

[AussieJimG]

I have seen it done as krv3000 says but it was done with the blades rotating backwards (using a crossed belt)

Jim

[David Jupp]

Grinding wheel should be set to ensure proper relief on the cylinder blades.  Cylinder blade sits a against a rest which traverses - a bit like sharpening sides of an end mill.

The 'spin the cylinder' methods are bodges to varying degrees as they won't put any relief on the blades.

[Lykle]

they won't put any relief on the blades

How much relief would you need for grass?
To me, not having to mow the grass is a relief.

Lykle

[hermetic]

Hi David Jupp.

"The 'spin the cylinder' methods are bodges to varying degrees as they won't put any relief on the blades."

The machine I saw was made By Ransome to sharpen cylinder gang mowers for professional green care, I don't think they would recomend a bodge up method of sharpening really!

[oldgoaly]

I actually bought one at an auction, based on a Atlas lathe, a nice tool post grinder is mine for 15$. Don't think I took any pics, still have the rest of the lathe parts, just in case?

[geoff_p]

I worked for a county-council where I had the task of sharpening several gang mowers.  We bought a machine from Ransomes and were told explicitly "No relief".  What had previously taken me hours with a small angle-grinder was reduced to a few minutes work for a far superior end-result.
Geoff,
Thailand

[David Jupp]

Looks like my information on this was incomplete - I stand corrected.

One thing to look out for on lower cost mowers, the bottom blade can become distorted (some are just a piece of pressed steel) -   if the bottom blade isn't straight, no amount of grinding the cylinder will get it to cut well.

[RussellT]

I've just been thinking about this.  I would have thought there is no need to provide clearance behind the cutting edge on the cylinder because it would be much easier to do it by setting the bottom blade to provide the clearance.

The cutting on a cylinder mower is by shearing so the cutting should actually take place in font of the blade.  I think the clearance is to minimise friction rather than improve cutting.

Russell

[Manxmodder]

Thought i'd ask you knowledgable lot first.... Its probaly been mentioned before somewhere

Traditionally i've used a file and gauged the amount being removed by the cutter bar...not entirely accurate but it ultimately cuts the grass

Anyone any idea how the pro's do it and if it could be replicated easily at home. i own a Harrison L5 lather so could remove and spin the cylinder between centres. i thought of making a traversing angle grinder holder but need ideas/inspiration

Hi Stig, I own an L6 Harrison and I have trued and sharpened a couple of mower cylinders in the past by mounting them between centres  and driven by a dog and faceplate setup,though a 4 jaw chuck would also provide a satisfactory mounting arrangement.

All I have ever used for this operation is a brazed carbide lathe tool and taken small cuts using the longitudinal power feed until the cylinder is cutting on all blades,then a final sharpen of the lathe tool to take the final cutting pass.

You need to spin the cylinder at fairly high rpm and feed at a slow rate to ensure the tool doesn't dig in.

If you go this route do some static checks on each blade with the cylinder mounted btwn centres to determine any abnormally high spots.....OZ.

[tumutbound]

Is this the style machine you're talking about?
Not sure of the brand on this one.

[stig]

  Hi Stig, I own an L6 Harrison and I have trued and sharpened a couple of mower cylinders in the past by mounting them between centres  and driven by a dog and faceplate setup,though a 4 jaw chuck would also provide a satisfactory mounting arrangement.

All I have ever used for this operation is a brazed carbide lathe tool and taken small cuts using the longitudinal power feed until the cylinder is cutting on all blades,then a final sharpen of the lathe tool to take the final cutting pass.

You need to spin the cylinder at fairly high rpm and feed at a slow rate to ensure the tool doesn't dig in.

If you go this route do some static checks on each blade with the cylinder mounted btwn centres to determine any abnormally high spots.....OZ.

Thanks for that, will give it a go when i get 5 minutes to tear down the mower. i'm also looking at creating some kind of jig to hold an air powered grinder run off the compressor and mount it to the lathe carriage...but that'll be another project for when I'm bored of sitting about on a sunny day