Ransomes cutting cylinder?

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Warpa
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Ransomes cutting cylinder?

Just reading the old owners manual about resharpening a Mk5 Ajax and a cutting cylinder was supplied with the mower. As I dont have one and dont know if they are even available anymore, what's the best thing to use assuming the blade is good and true, but just needs to keep its edge?

wristpin
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Not quite sure what you are

Not quite sure what you are asking but the cutting mechanism consists of rotating blades known collectively as the cutting cylinder and a fixed blade known as the bottom blade or shear blade.  So unless the machine has been robbed of one or both you have what you need. Then it is a question of condition. The rotating blades act against the fixed blade to shear off the grass , each rotating  blade acting as one half of a pair of scissors. If your scissor blades are badly rusted , are rounded or have suffered impact damage they will need to be sharpened or re- ground. The same applies to the mower.

Warpa
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It mentions a grinding in pin

It mentions a grinding in pin and using grinding paste on how to sharpen the blades in the owners manual. I cant copy and paste what it says, but the file is available on this website.

wristpin
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Ah, that refers to the

Ah, that refers to the pin needed for back lapping, a maintenance procedure for keeping an edge on a cylinder that is in good condition. It’s not a substitute for a re-grind on rusty, rounded or “ dinged” blades.

Search this forum for lots of information and differing views on the pros and cons of back lapping.

Warpa
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Dam you wristpin (shakes fist

Dam you wristpin (shakes fist) now I'm even more confused.

I pick up a full professional restored Ajax tomorrow and also have one to work on in my shed. Being a carpenter I like my tools sharp, and this back lapping doesn't sound quite right, BUT if backlapping is what Ransomes say to do in the manual then the blade must be good for it, and they say once a season.

Let's assume the blades on the new mower are mint and ready to go, how often should they be given a sharpen next season, baring in mind I'm a lawn nut and generally need to cut every 2 days.

Can I properly sharpen the old mower blades as practice, of so what is available to buy to get it done properly at an affordable price? Can those old cylinder grinders be picked up readily and cheaply?

wristpin
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First. Back lapping is a

First. Back lapping is a maintenance procedure which, baring accidents will maintain a correctly sharpened cylinder in tip top condition. If the blades sustain impact damage they will nee to be sharpened ( ground) on a machine costing many thousands of pounds if bought new**. Used grinders do turn up on auction sites from time to time but a quite large bits of kit - think a freestanding metal working lathe and often require a three phase power supply .

So back to back lapping . You need a means of turning the cylinder such as a speed brace from a socket set  and some water based grinding paste, then you are set to go. The pin that you mention would screw into a threaded hole in one of the drive gears to provide a means of turning it. I believe that on some models Ransomes made provision for one of the handle bar grips to be unscrewed and repositioned on to the driving gear to aid turning.

How often - just like your chisels and plane irons - when they are dull! With a push mower, not only will correctly set, sharp blades cut better, but the machine will be easier to push. 

** Grinding a 30" cylinder.

 

 

 

hortimech
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If you wait until you think

If you wait until you think the cylinder blades are dull, you have waited too long ;-)

Backlapping is a maintenance procedure that must be carried out on a fairly sharp cylinder, the analogy would be that you would grind a wood chisel and then hone it on a whetstone to finish it off, you then keep it sharp by periodically whetstoning it.

The other things that Wristpin didn't say, you have to turn the cylinder backwards to backlap and you must wash off any backlap paste before turning the cylinder in a forwards direction. You can buy machines to turn the cylinder for you, these are basically a motor and right angle gearbox and spin the cylinder at the optimum 60-100 RPM. 

Warpa
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Thanks for that chaps. So I

Thanks for that chaps. So I'll send the cylinder away to be properly re ground. On return I'll need to backlap it to hone it in? How do you back lap, put cutting paste on the bottom blade and lower the cylinder untill it just skims it?

Another thing that I cant quite understand is when lowering the cylinder to make contact with whatever sharpens it is how to keep it perfectly level. Is it a case of as you lower it you do so untill each end is touching the bit that sharpens it?

wristpin
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Have the bottom blade skimmed

Have the bottom blade skimmed while attached to its carrier (aka sole plate or bottom block) even if you’ve fitted a new blade. With a fresh ground cylinder and skimmed bottom blade you shouldn’t need to back lap but it won’t hurt if you do. 

Paste is normally applied to the blades . If you are concerned about getting the cylinder and bottom blade parallel, use a bit of 80gm copy paper as a feeler gauge.

Warpa
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I found a place local to me

I found a place local to me to re grind the blade and set the mower up, his face lit up when he saw it was an old Ransomes. When I collect it he will run through how to keep a good edge on it. I need to print out a copy of the owners manual as I prefer being able to flick back and forth with a paper copy.

I'd like to get a season out of mowing without any sharpening but doubt that will be possible cutting every 2 days in the growing season. Having said that I'm sure my grandad never sharpened his, not that I would have been paying much attention.