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Collection, Preservation and Display of Old Lawn Mowers

Using the Dual

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Referring to my earlier post and specifically a comment from Hortimech where he says the idea is to grind away any taper that may have developed in the cylinder over time - well how is it best to go about doing this?

playing around with the machine again today with a couple of dead cylinders, I began to wonder how to work out if the mainshaft is level. My original plan was to set the stone on one end of the cylinder and then do likewise at the other end. But if I do this I guess I am probably just following any taper in the cylinder, correct?

in the end I settled on a small spirit level placed at various points on the shaft. Is this a good idea or can someone point me in a better direction please?

im not a commercial user so if it takes me 20 minutes or so to dial it in properly that isn't an issue.

thanks again

Forums

hortimech Wed, 09/12/2020

The later versions of your machine had a gauge in each of the large adjusting hand wheels, these allowed you to level the stone shaft, you need to use another way. First, your machine must be set level and it must stay level, not sure what your machine is sat on, but it must hard and level. this means it shouldn't be stood on a wooden floor or concrete flagstones, Whenever I set one up, I created a hard pad using a grano mix (not standard concrete). Once your machine is set level, you can then start to setup the stone to cylinder contact. You do this by bringing the stone up to the cylinder, trying to keep the stone shaft level to the cylinder shaft. At this point you need a depth gauge (which used to come with the machine), this is used to measure the distance between the cylinder shaft (at the ends) and the stone shaft, adjusting the hand wheels to level the shaft and keep contact between the stone and cylinder. You will probably find that whilst you can level the shaft, the stone doesn't touch the cylinder all the way along its length. You should also be aware that you are not trying to get a totally precise setting, a best effort is all you can expect. Once you are happy, mark the large hand wheels with coloured tape, then start grinding. When adjusting the stone to cylinder contact, refer to your marking tapes and turn both hand wheels the same amount, continue grinding until the cylinder is ground all the way across, but whatever you do, do not let the cylinder spark out, the last pass should be of a heavy cut.

 

Will Thu, 10/12/2020

Thanks so much for the detailed reply Hortimech, very good of you.

i can confirm that it's sat on a solid concrete floor and I've got it perfectly level (well according to my spirit level anyway!) it's not movingly an inch.

i knew there must be a proper technique to it! What you've said makes a lot of sense, the only thing I need now is a depth gauge to perform an accurate measurement. I know there are various different types available and I have one, of sorts, on my Halfords vernier calipers, but I'm assuming something more specialist is required, which I'm happy to purchase.

its a long shot but do you by chance have a photo of the type that would have been supplied originally??

thanks again

Will Thu, 10/12/2020

Ps - Yes I note in the Bernhard manual it states 'Apply a good hard cut - do not be afraid of the aggressive nature of the grinding process' !

wristpin Thu, 10/12/2020

Yes I note in the Bernhard manual it states 'Apply a good hard cut - do not be afraid of the aggressive nature of the grinding process' !

I presume that the Dual has a wheel dressing attachment ?  A hard cut with a dull polished wheel is of limited benefit .

Will Fri, 11/12/2020

I'll have to have a look, I'm not sure there is actually, but the wheel on it looks fairly fresh to me. Are the wheel dressing devices hard to find??

wristpin Fri, 11/12/2020

Stone dressers. In their basic form they are just a pack of star wheels in a handle,  but based on my purely BRL experience the star wheels are held in an attachment that clamps to the machine so that the grinding wheel may be moved across it in a true parallel path.  I presume that your machine would have been supplied with a dresser of some sort when new, possibly a diamond dresser which might look like a metal rod with an industrial diamond set in one end.

hortimech Fri, 11/12/2020

No, Pandawill's machine wouldn't have come with a stone dresser, it was only the later Anglemasters that came with the diamond dresser built in.

 

Will Fri, 11/12/2020

So, assuming I will need to dress the stone once in a while, what's the best way to go about it on my machine? Thanks in advance