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What is back lapping,for the uninitiated?Any particular skills/equipment reqd?

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wristpin Fri, 17/03/2017

Very simply the application of grinding paste to the blades of a cylinder mower while rotating the cylinder in the opposite direction to cutting.

It is a maintenance operation , performed on cylinders  on which the blades have been "relief" ground, to keep them in tip top condition;  it is mainly, but not solely,  used by professionals on professional equipment .  It is not a recovery option for blunt, rusty or damaged blades.

 

hortimech Fri, 17/03/2017

As Wristpin says, but with a couple of changes, it isn't grinding paste, it is backlapping paste, there is a difference. Grinding paste is usually oil based and backlapping paste is water based. You can backlap any cylinder, it isn't just for 'relief' ground cylinders, the only requirement is that the cylinder is nearly sharp to begin with.

 

wristpin Fri, 17/03/2017

You can backlap any cylinder, it isn't just for 'relief' ground cylinders, the only requirement is that the cylinder is nearly sharp to begin with.

Yes you can backlap any sharp blade but if there is no relief it wipes the past off very quickly. It is the relief that forms a reservoir for the paste trapping it to be more effective. Relief is the small angle on the back of each blade which, when the cylinder is rotated in reverse, arrives first at the bottom blade with the paste trapped in it for increased effectiveness.

hortimech Sat, 18/03/2017

'if there is no relief it wipes the past off very quickly.'

I never found this to be a problem and I quite possibly backlapped more cylinders than you did. I was a Toro technician for over 25 years ( I also have the jumper to prove it) and used to train Greenkeepers how to backlap. You do not have to 'relief' or 'single blade' grind a cylinder before you can backlap it, Most Toro greensmower units are spun ground and these used to come with a speed brace to manually backlap them. There was also the Toro 1000 single greensmower, I defy you to relief grind the cylinder in that, approx 3.5 inches in dia with 11 blades.

 

wristpin Sat, 18/03/2017

Not a lot that I can do about the date of birth so I'm not entering the " hot breakfasts" debate, but this makes interesting reading.

http://www.huntergrinders.com/about_sharper.htm

Also, In their specifications for their grinder they make the point that their small diameter grinding wheel   Makes them suitable for relief grinding  " small diameter, multi blade cylinders" . However, how small and how many blades is not specified.

hortimech Sun, 19/03/2017

I once had a discussion with Eric about the Jupiter grinder and using it to grind bottom blades. My argument was that, yes it could grind them, but it was a complicated. You had to set up each bottom block from scratch and in the time it took to grind one GM3 blade, I could grind all three blades in the Anglemaster. He couldn't come up with a valid argument to rebut what I said.

I also learned a long time ago, do not believe anything in an advert or what a salesman says, without checking for yourself.