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Collection, Preservation and Display of Old Lawn Mowers

Grinding paste

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Hi, after doing a little you tube browsing on cylinder backlapping, I fancy having a go at doing it myself on the Suffolk swift I've recently used on my lawn. I'm happy with the set up, the cut is short, and the mower works well, but I'm curious at how much this can be improved by the maintenance process of backlapping. A few questions to the experts reading this, Flowers of emery has been mentioned on similar threads but I cannot find any being listed for sale, is there a preferable equivelant that is readily available? Valve grinding paste comes up a lot when searching, can this be used or is it a completely different product? And probably answering my own question but I'll have to take the drive chain off the cylinder beforehand I presume, does this depend on ratchet system on the rear roller or is it just the safest and right way of going about it. Regards. Lee

Forums

hortimech Mon, 11/05/2020

If your cutters are 'sharp', then backlapping can be effective in keeping them 'sharp', but it will not sharpen them if they are even the slightest bit blunt.

Having got that out of the way, no, you cannot use valve grinding paste, this is because, whilst the abrasive might be correct, it will be suspended in oil or grease. The correct backlap paste is water based, this allows all the paste to be easily washed off, something that is hard to do with valve grinding paste. Once you have lapped the blades, do not turn the cylinder in a forward direction until you have fully removed the paste.

Lee Smallwood Mon, 11/05/2020

Thank you for the clarity on valve paste Rowland, never thought about the oil/water based reasons, but now it makes sense, seeing some of the "clumsy" videos on you tube, making sure cleaning the cylinder afterwards, although obvious to some, thoroughly cleaning it may not be. The cylinder is pretty sharp and cuts evenly across, but as its an easy mower to work on I thought I'd try this process out and have some idea of how sharp it really was, plus having an idea of how sharp a cylinder mower can actually become once backlapped, I will continue my search for some decent paste, water based of course, and once I've hopefully achieved a non clumsy back lap, I will post my findings to you all, that is unless I've lost both my thumbs in the process. 

pindernick Mon, 11/05/2020

Hi Lee, I swear by back lapping my Morrison Olympic 400 for keeping the reel in fettle. Such a satisfying process. I've made a chuck to go on my cordless drill onto the reel sprocket and it works nicely. I'll check what lapping paste I have in the shed tomorrow and let you know. It was hard to find, but I think I searched for compound for grinding gears.  

pindernick Tue, 12/05/2020

Chemico is the stuff I got online and 2.5kg will last me a hell of a long time. My go to is 120 grit. 

Hope that helps and enjoy. 
Nick

Lee Smallwood Tue, 12/05/2020

Thank you, that size will outlast me I reckon, look forward to trying it out. Cheers.