Exploding Grinding Wheel

I think that's drawing a rather long bow. But lets not get involved in politics. Nils illegitemi carborundum.

But were you aware of the lense grinder who fell into his machine?

Made a spectacle of himsel

Ok. Ok. Ill get me hat.

Edited By Hopper on 30/06/2020 11:37:43

What surprises me, is that new grinding wheels are sold, with no instructions about crack or ring testing the wheel. Broken wheels don't happen all that often, but only once is too much. Last year a friend went to start a cylindrical grinder. It had a newly mounted and dressed wheel the week before that was ring tested. It broke almost perfect in half with the two pieces flying out like a brake drum shoe set. The motor stalled and the fuse failed all before he hit the e stop button.

As an apprentice we were taught to stand to the side of the grinder when starting, and be on the side of the main power switch or wall outlet. Wait a few seconds, then use the grinder. Never stand directly in front on start up. All the wheel failures I have seen or heard about have occurred during or very shortly after it has got to full RPM on start up.

I just came across this idea of bonding a wheel to a backing plate for face grinding....

https://books.google.co.uk/books?id=N9gDAAAAMBAJ&pg=PA184&lpg=PA184&dq=cupwheel+arbour&source=bl&ots=rRELtOhn9f&sig=ACfU3U1YrkSDsGU7-PMyNfbGMkmAG7ns1w&hl=en&sa=X&ved=2ahUKEwj47_ePtanqAhUMXsAKHX2RBlwQ6AEwEnoECAoQAQ#v=onepage&q=cupwheel%20arbour&f=false
Link

Ona related subject they also suggest similar for a cup wheel but that doesn;t srike me as such a goos diea with no arbour plate inside.

I do have a cup wheel on order and was wondering how best to mount it on a home-made arbour... additional soft paper washers? It'll only be run at 2K rpm

pgk

I just came across this idea of bonding a wheel to a backing plate for face grinding....

The company I did my apprenticeship with had a vertical spindle surface grinder (may have been an Abwood) in the toolroom that had an abrasive ring "wheel" bonded to a steel backplate. The bonding material was heat softened - to change a wheel, the backplate was heated until the old wheel could be removed & the old adhesive removed with a wire brush to clean out the recess in the backplate. New adhesive was a yellowish brown powder that melted to a smelly dark brown thick paste when it was applied to the hot backplate. A new abrasive ring was settled in the hot paste & left to cool before remounting and dressing. There is a swinging head "die punch" grinder with a similar wheel arrangement where I work now - it could do with a new abrasive ring, but I have not investigated changing it as the machine gets negligable use.

The toolrom roof had a hole from a bursting cup wheel on a tool & cutter grinder - small wheel, but a bit of it still managed to get two stories high & have enough energy to punch through what was probably an asbestos sheet roof panel. The hole was duly pointed out to all incoming apprentices as a warning not to mess about with grinding wheels.

Nigel B.

I bought a bench grinder last year from Lidl, the type with one end geared down to about 120rpm with a large wet wheel for wood chisels and plane blades. That is too slow to be dangerous except for trapping fingers. The full speed wheel at the other end was removed and binned and a mandrel for a 100mm electroplated diamond wheel. This is made from aluminium and cannot shatter. The grinder has been mounted on an aluminium base with an adjustable rest for the diamond. These diamonds can be used for HSS, but as steel will cause chemical decomposition of the diamond, the life will be reduced. For limited home use, it probably wouldn't matter much.

For grinding wet, the rule always to be observed is that you must turn off the coolant before the wheel. This ensures the wheel is pretty much dry before it stops turning. If the wheel is stopped while wet, the coolant will end up at the bottom of the wheel as it slowly drains away, and the wheel will be very out of balance when starting up.

Out of curiosity, in what part of the world did you grow up?

My grandmother grew up on an Oxfordshire farm and always called a trough a trow, but I've never heard anyone else use the word.

Neil

Yes, please avoid getting into the politics of Covid-19. Rather than have a discussion here anyone interested in the statistics can visit the link below which offers figures without any interpretation .

Neil

www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/deaths/bulletins/deathsregisteredweeklyinenglandandwalesprovisional/weekending19june2020

Never complacent about anything whirring round.

Since my new white wheel arrived I don't even have to press hard to shift metal so there's even less stress (mechanical and mental)