Back Lapping Paste
Quick question (I did search on the forum before but could not find the exact answer) for those that have used back lapping paste before. Which brand do you find the best and where can I buy it? Which grit level should I go for in "normal" maintenance use? Can I use valve grinding paste?
Re the grit level I find that when I use my current lapping paste the centre of the cylinder makes that loverly light grey texture but at both ends the paste wears quickly off. I was thinking a higher grit level initial to help even it out. The cylinder ends are not blunt and still offer a good cut but are maybe not as sharp as the centre.
You can buy it from several places (just do an internet search), most Golf clubs would normally use a fine grit grade on a weekly basis, but you must use a water based paste, so that rules out valve lapping paste.
Backlapping is a maintenance procedure, you cannot use it to repair a cutting cylinder that requires regrinding.
Is there a specific brand you recommend? I have seen it only for sale in large tubs.
How do I know if the cylinder requires regrinding? The centre of the cylinder is sharp and passes the paper test (where it cuts paper without pulling at it). It is just the sides that do cut just but also pull slightly plus the centre has a nice clean edge on the blade whereas the side are not really touching the paste enough.
Here we go again!!!!!!!
From your description, both the cylinder and bottom blade need to be re-ground.
Plus, for backlapping to work properly the cylinder needs to have been relief ground. It is the little gap at the back of each blade of a relief ground cylinder that traps the backlapping paste and keeps it working. With no relief, on the first reverse rotation of the cylinder the bottom blade wipes most of the paste off.
There is a very good Toro tutorial on the whole subject of cylinder (reel) mower theory and practice but it seems to have been taken down from where I used to find it. If I can find where its gone I will post it later.
The important bit!
Maybe 2 PDF's to be put on the site?
It's on the list of things to do but so are lots of others.
many thanks - I know why you started with "Here we go again!!!!!!!" - I read the post on the same topic from 2013........
last question (for now) - I live nr Towcester, South Northants - any recommendations on trusted professionals that will be able to re grind / service my 1960s Atco? Villiers MK 10 engine.
Steve is frequently called on the forum:
Thanks Henno. I had seen this type of listing and I am glad to know that they come recommended by the gurus on this forum.
I have a 1960s Atco 24". I will attempt to remove the cylinder and bottom blade this weekend. Hopefully it is not too complex to remove but may revert for advice if needed.
Thanks as always,
It’s fairly straight forward but one tip the may save you some grief. When you have removed the outer sprocket on the cutting cylinder you are confronted by a “ tempting” hexagon adaptor. This does NOT unscrew but pulls off the end of the cylinder shaft. Every now and again we would see one that had been attacked with a two foot ring spanner and twisted beyond re use.
Before trying to withdraw the bottom blade sole plate assembly , slacken off the two adjusting screws at either end and when reinstalling don’t over tighten those screws as the rocking levers that they act on are “ cast” and can snap like the proverbial carrot if over tightened.