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  1. #1
    Join Date
    Dec 2007
    Location
    Adelaide
    Posts
    574

    Default Question about T&C grinder wheels.

    I've finished the spindle of my T&C grinder project and trial fitted a cup/cone shaped wheel (white stone), I sized the grinding wheel locating bush such that the wheel would be a close snug fit on the bush and I see that there is a small amount (1mm or so) of run out on the wheel, it looks to me that the locating bush should be a slightly smaller to allow a small amount of movement so the wheel can be set to run true, is this how it's done ?

    Other than that the only the other option that I can see is that the wheel is trued up with a diamond dresser on all surfaces - this however does not make sense as it would mean taking a few mm of each face ie front, outside diameter and inside diameter, this would reduce the thickness of the wheel by up to 5mm or so.

    There may also be some out of balance as when spun over by hand the wheel stops in the same position 90% of the time although this may be caused by the runout, do wheels need to be balanced ?

  2. #2
    Join Date
    Dec 2005
    Location
    South Australia
    Posts
    1,656

    Default

    The wheel should be mounted on it's own separate hub that is running true and balanced before fitting it to the machine
    if the machine is running true, all should be well, then the wheel is dressed to suit

  3. #3
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Familyguy, Guys,

    All grinding wheels need dressing before use, particularly surface and TCG wheels. A diamond dresser should only be allowed a couple of thou per cut, much more and you run the risk of dislocating the diamond and loosing it. For the same reason the diamond should be angled slightly down rather than straight into the wheel.

    The hole in the wheel and the size of the hub should be a good fit without being tight, any runout will be taken care of by the diamond dressing. If you really need to take more than a few tens of thou off the wheel then the wheel is bad and should be treated as such. I bought a white 80 grit cup wheel to play with some time ago and found that it is very well balanced.

    Balancing is another problem, although I've found that dressing the wheel usually takes care of most out of balance conditions. Though as China says the wheel should be balanced in place on a hub. Grub screws in a hub to secure it to the spindle are a no no because they will cause an out of balance condition.

    I'm curious to know what design of TCG you are building, since I'm also in the process of building one based on the "Brooks" design but with my own adaptations. At the moment I'm working on the X-Y table design.
    Best Regards:
    Baron J.

  4. #4
    Join Date
    Mar 2014
    Location
    South of Adelaide
    Posts
    1,225

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    what brand of wheel do you have? I have never had this problem with the Norton wheels i use. You could have a dud wheel.

  5. #5
    Join Date
    Dec 2007
    Location
    Adelaide
    Posts
    574

    Default

    The wheel is a light push fit onto the hub I can not detect any play, the hub is turned in one piece it was roughed out about about .005" oversize and then mounted on a stub in the chuck and the final cuts to bring it to size were done in one setup. Once located in the spindle I can't really measure any runout in the hub - it's certainly better than 1/2 a division of my dial gauge which has .001" divisions so I'm sure the hub is all good.

    The wheel, it is marked The Carborundum Company Traford Manchester I have two, they were given to me by a retired toolmaker he was returning to the UK to live out his days close to his family. It is quite possible the wheels are bad, the tool maker gave me all of his personal gear micrometers, old style vernier calipers etc. and around 25Kgs of new and used HSS lathe tool bits and morse drills. Some the gear was damaged like broken drill bits and milling cutters and badly scored morse reducing sockets so it is possible he did not like throwing things out and kept the wheels even though they were bad

    I have a copy of the Deckel SO cutter grinder manual and it states that a small amount of play between the wheel and hub allows the wheel to be centred for true running. It was after reading this that I thought I might be going about this the wrong way. I've done a lot of google and youtube searching and have been unable to find any good info on the actual complete process of mounting a grinding wheel, most just say mount the wheel and then true it with a diamond dresser, strangely though I found that it is the woodworkers that go into wheel mounting in greater detail but not sure if their info is relevant as a bench grinder used for chisels is not quite the same as a T&C grinder. I'm a bit reluctant to machine down the hub to give the wheel a bit of play as there is a few hours work involved in making one.

    Baron - I read your post in the Projects section I'll be following it to see how it all turns out, I hope it all goes smoothly for you, my project is a Quorn, I was given the castings as a Xmas present back in the early 80's I think they cost $AU70 from an Oz supplier and it is only now that I have retired that I have found the time to complete it, perhaps it is just as well as I now have 30 odd years more experience in machining and if I had tried back then I would probably have stuffed it up. All of the major machining is finished, I left the spindle till last as this scared me the most and as luck would have it I was given a worn out .17 cal rifle barrel which made a nice axel for the spindle. I've heard both good and bad about the Quorn and have yet to make up my mind once I start using it, what suits one person may not suit another, I have an acquaintance that got rid of his Honden lathe calling it rubbish because it did not have a camlock chuck.
    20190407_081512.jpg20190407_081542.jpgDeckel manual capture.JPG

  6. #6
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Familyguy,

    You might find that the wheel is too tight on the hub ! It should go on without having to apply any pressure. Part of the issue here is that the hole in the wheel can vary slightly from wheel to wheel. Another thing that I've found is that the blotter on the wheel can be thicker in some places than others. I've put this down to the blotter getting damp and swelling in one place, often where the printing is. New blotters solves that issue. That could also be the cause of vibration as well.

    I don't think the Carborundum Company exist any more. The last wheels that I bought were San Gobain ones from Abtec here in the UK. I'll dig them out and post a picture.

    https://www.saint-gobain-abrasives.com/en-us/products

    Re the Quorn. I've looked at that one and decided that there are too many handles and knobs to play with
    Having said that I know a couple of guys that have them and at least one of them describes his as the "Swiss Army Knife" of the grinder world.

    Thank you for your nice comments about my TC grinder project. Like you retirement has given me time to be able to play about with things that I could never find time for.
    Best Regards:
    Baron J.

  7. #7
    Join Date
    Dec 2007
    Location
    Adelaide
    Posts
    574

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    A recent edition of Model Engineers Workshop has an article on replacing the regular Al Oxide grinding wheel with a CBN wheel designed specifically for tool and cutter grinders, the author of the article uses a wheel from an EMG20 grinder, if you don't know this beast it looks like a space age tea kettle and is in essence a tool and cutter grinder for the time poor, look it up and you will see what I mean - takes all of the setup time out of the equation. The author made the change as he did not like the mess made by wheel grit every time a wheel is dressed, the EMG20 wheel has a number of different faces and edges so all aspects of end mill sharpening can be carried out including gashing between the teeth all with the one wheel and not a single diamond dresser in sight. Once I have given my grinder a bit of a trial and if I find it useful I'll probably switch over to an EMG20 CBN wheel for end mill sharpening, but for now I don't want to fork out $200 only to find I don't get any use out of it.

    I noticed that the blotter looked a bit suspect so I've already got some new blotter material.

    I've given my wheels a bit more of a look and the run out while not good is not as bad as I thought, I measured it at around .02" or 0.5mm and could be trued with a dresser however what is worse is that the side walls of the wheels are thicker on one side than the other probably due to dressing the outside of the wheel and not the inside, I'm guessing it will lead to out of balance issues. If I can find a way to fully contain the grit and keep it away from sensitive parts of the lathe I will try to true up the inside of the wheels in the lathe, I'll run it at a really low speed somewhere between 60 and 100 rpm and the wheel should powder away nicely with out flinging grit all over the place, an old masonry drill should work as the dressing tool for this.

    Yes the Quorn does look a bit crazy with all of those ball handles sticking out, looks like a bit of a job to get them to all tighten with fouling against some part of the machine, I'll be using machine handle/knobs from ebay the type where the handle angle can be adjusted easily. Once it is operational I'll post some pics in the projects section.

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