I hit on this idea so I can post the odd unrelated snippet etc with impunity. Or just say nothing here.
So there was a need to make a set of angle wedges at 50° for use in the machine vise when milling ramps at this angle. They need to be accurate and identical so I rivet two slabs of 10mm mild steel together after surface grinding one face on each, then machine them as one unit and separate them when all is done.
I use a bevel box and an angle gauge to mark and check the angle.
Pictures follow.

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Philip Marcou

It's amazing how the two pieces vanish into each other, Philip.

I notice that the cover on your grinder is nubbly and black. Is that from grinder detritus, or was it made that texture/color? What comes out of the tube that points at the thing being ground? Just air?

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I don't have as many Festools as Fred. Or Marcou's, or Brese's, or Lie-Nielsen's, or Lee Valley's, or Blue Spruce's, or Harold and Saxon's, or...

Peter,
Yep the grinding process produces millions of small nubs, which conglomerate on all surfaces within range. In fact the whole exterior surface of the machine is coated in nubs composed of grinding dust. I only clean it down occasionally as the act of washing off the dust can cause it to get into places where it causes damage. Only the magnetic table surface is kept spotlessly clean as particles can scratch the work and even raise it a thou or so.
Surface grinders are dirty and that is why it isn't in my shop proper. In dedicated engineering tool rooms they go to extremes preventing that dust spreading.
The tube sprays grinding fluid onto the work-also reduces dust spreading.

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Philip Marcou

Thanks Philip. Do you think your lungs look like the outside of your grinder?

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I don't have as many Festools as Fred. Or Marcou's, or Brese's, or Lie-Nielsen's, or Lee Valley's, or Blue Spruce's, or Harold and Saxon's, or...

No, I breathe through my nose, which is a filter.....And I don't talk to myself , sing, or talk to anyone else when I am working ie I keep my mouth shut and breathe through my nose.
Seriously, judging by the results when blowing my nose, none of those nubs are getting into me....I would see black , er , matter on the tissue.
But wood dust is another matter, and the inbuilt filter can't cope without external assistance.
The grinding fluid kills all the really fine dust. If you don't use this fluid you can actually taste that metallic flavour-which means the nasty nubs are getting into the body. I don't like that metallic flavour.
Incidentally: brass fine dust smells and tastes like onions.....

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Philip Marcou

Calling Kevin Ross: I can't respond to your private message unless you change your settings to accept e mails

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Philip Marcou

A surface grinder consumes grinding wheels like corn off the cob mainly because one needs to dress the wheel often, if consistent results are to be had.
I would apply the following to either a surface grinder or your normal bench grinder when fitting new wheels:-
1) The ring test -hold the wheel on one finger and tap it with another finger (!)-it should "ring" and not make a solid sound sound. If it doesn't ring it is cracked and will shatter ....
2)In my case the plastic bushing is about 10 thou oversize for my machine so I have made brass bushings with the correct internal diameter of 31.75mm, so I just knock the plastic out and insert the brass.
3)These are Norton wheels and ever since they stopped sending me ones made in Australia I find that the ones made in China are badly out of true-they require dressing on the sides and the working face. Runout of up to 40 thou is not unusual and must be corrected. Pictures show ....

The last picture is a chart which explains what all the numbers etc mean on those wheels.

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Philip Marcou

I always wondered how you can get accurate surfacing with something that breaks down as it's used.

That is a valid question. I can tell you from experience with my particular machine as applied to slabs of mild steel seen on my planes that unless I pay attention and dress the wheel constantly the wheel will start at say a depth of 4 thou but by the time it reaches the full width of the work piece it is cutting at somewhere between 3 and 4 thou-so I never just take one pass and always swap the work piece end for end on the same face and take another cut to cancel out that effect, and always cut with the same leading edge ie the one nearest to me.
The other thing is if you watch the wheel face you can see that the part doing the work is right next to the leading edge -there is a narrow ring of red- as the wheel wears this red ring moves towards the trailing edge and it is then time to dress the wheel again when that red line is right at the trailing edge.If you just continue grinding without dressing the surface pattern quality deteriorates at that point in addition to a loss of accuracy.
The above is assuming that one uses the correct wheel for the job-generally along the lines of hard steel requiring a soft wheel and soft steel etc requiring a hard wheel. If you get neurotic about it you can end up spending more too much time changing wheels for different applications so the idea is to find the happy medium . If you bear in mind that a plane maker will be grinding mild steel, annealed tool steels, hardened tool steels and brass (at times the brass and mild steel require to be ground at the same time ) then you get the picture. I use the wheel grade you see there as recommended by the supplier, but have tried those blue SG (seeded grit) and prefer the white ones. Pink stones are very nice for hardened steels. And on it goes.....
It would be nice to have a massive machine with a wheel width of 11/2 inches or more so that some of these problems are not so acute but these machines are super expensive. Now you begin to know why Uncle Karl needs to recover some expenses when he churns out his planes- and you are so lucky to get planes from me at such marvelous prices

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Philip Marcou

That's what I was afraid of...nothing is as easy as it looks.