Tool Post Grinder

Discussion in 'Tools' started by Ghosty, Jan 23, 2018.

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  1. Jan 23, 2018 #1

    Ghosty

    Ghosty

    Ghosty

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    Hi All,
    After looking around, I have started making my own grinder.
    Power is a 500watt brushless motor, the shaft is a 20C ER20 150L collet shaft. Bearings 20mm x 32mm x 7mm, I used 4 to support the shaft, used a toothed belt with a 2-1 ratio. The brushes motor max speed is 12000rpm, so can get better grinding spindle speed control.
    I have the basic setup done, with only some fine tuning to finish.
    I still have the grinding wheel arbour to machine, will fit the ER20 collet shaft end.
    The main body is machined out of a piece of 100mm x 100mm x 50mm alloy block, the motor mount spacer, is a piece of alloy 25mm x 40mm x 110mm, which is bolted to the main body, and then the motor mount is bolted to the spacer.
    The alloy is what I had in the spares bin, the motor came from another project, and the belt and pulleys were extras from another project, bearings are used in a 1/5 Baja buggy that I run, only thing I ordered is the ER20 collet shaft. I also have a C12 ER11 150 collet shaft that can be set up to do internal grinding.
    Will ad more as the project moves forward.

    Cheers
    Andrew

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  2. Jan 23, 2018 #2

    Herbiev

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    Looking good so far. I'll be following along.
     
  3. Jan 23, 2018 #3

    Brian Rupnow

    Brian Rupnow

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    Nice work Ghosty. I have been trying to find a company that makes a toolpost mounted grinder like that one and had no luck. I would buy one if I could find a company that sold that style.---Brian
     
  4. Jan 24, 2018 #4

    Ghosty

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  5. Jan 24, 2018 #5

    Ghosty

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    Hi All,
    Started on the arbour to hold the grinding wheel. Have to wait for the wheel to arrive, but will hope to finish the arbour today.

    Cheers
    Andrew

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  6. Jan 24, 2018 #6

    Brian Rupnow

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    Ghosty--I've seen that as well, but in order to mount that on your lathe you have to remove the topslide. I would want one that actually mounts to the toolpost so it could have angular adjustment for grinding tapers.
     
  7. Jan 24, 2018 #7

    Ghosty

    Ghosty

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    Hi All,
    Grinding wheel arbour finished, can be removed from the ER20 collet chuck and a 12mm collet used with a C12 ER11 150L collet shaft and with the use of smaller grinding stones, it can be used to do internal grinding.
    I still have the mounting hole to drill, stuffed up my back again, twisted the wrong way so will not be doing any more today.

    Cheers
    Andrew

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  8. Jan 24, 2018 #8

    goldstar31

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    Ghosty and Brian

    I don't know whether the undermentioned. is pertinent but my tool post grinder is a Bosch POF45 which I bought as a wood router some considerable number of years back. When I opened the box, the instruction were that it was actually a tool post grinder with a standard 43mm collar. Of course the collets came with it for router cutters.

    Cheaper still were the wood routers from sources like Aldi and Lidl.

    Following a circuitous route( other peoples's), the wood router was /is the propulsion unit for the Brookes tool and cutter grinder which was described in Model Engineers Workshop 16 and 17 and mentioned in the excellent GadgetBuilder.com website.

    I hope that this is interesting and 'constructive'


    Norm
     
  9. Jan 24, 2018 #9

    Ghosty

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    Hi All,
    Testing the drive and motor for the first time, forward and reverse.
    [ame]https://www.youtube.com/watch?v=wqEgP0rsWfM&feature=youtu.be[/ame]

    Cheers
    Andrew
     
  10. Jan 24, 2018 #10

    Blogwitch

    Blogwitch

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    Hi Andrew, just a comment about wheel speed.

    I used to use my TG a lot, and looking at your setup, you will not be reaching the speeds required for grinding correctly, especially internal surfaces.

    I have twin sheaves on mine, for internal and external, and both increase the speed from the motor (18K RPM ?) to the required speed for the stones. The belts used are flat plaited ones that when running on a convex pulley face allowing slippage if anything starts to get overwhelmed.

    I am using a 2.5" stone for external and standard 1/8" shank mounted points for internal.

    Maybe you should look at swapping your two pulleys over to get more speed from your TG.


    John
     
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  11. Jan 24, 2018 #11

    Ghosty

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    John,
    I all ready have a internal grinder, made up to do one job, good for 30K rpm, bearings are not quite up to the job, will be rebuilding with larger bearings.
    Blue sealed bearings are what I used, will be replacing with 6001's

    Cheers
    Andrew

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  12. Jan 25, 2018 #12

    Blogwitch

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    They reckon angular contact bearings are the best ones to use and preload them.
    If you are going to use those bearings you have, then make a spacer tube the exact distance between the inside bearing surfaces, then you can slightly preload them so they don't move in and out as the bearings warm up.

    My old TG doesn't have ballraces, but in fact are plain bronze with the internal of the spindle tube filled with oil. It has never leaked out at all. Supposedly plain bearings give a much better finish as they don't 'rumble', just like old plain bearing lathes.


    John
     
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  13. Jan 25, 2018 #13

    goldstar31

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    In my reply to Jon( JC Steam), I suggested that a cheap commercially available wood router could be suitable for similar loadings to those with the loads of routers. I can only surmise if firms like Aldi and Lidl who sell these things at knockdown prices still guarantee them for THREE years in normal hobby use and without quibble.

    Makes me think, if no one else.

    N
     
  14. Jan 27, 2018 #14

    DJP

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    A wood router as a tool post grinder has already been logged in my project files when you first mentioned it. Thanks
     
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  15. Jan 29, 2018 #15

    Ghosty

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    Hi All,
    Belleville washers, and grinding wheel arrived, now to do the final clean-up and assembly of the grinder. It seams to work well, need to work out cutting speeds, the grinder was running at 4200rpm and the lathe running at 1000rpm.

    Cheers
    Andrew

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  16. Jan 29, 2018 #16

    Ghosty

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    Hi All,
    Got the grinder fully assembled, Now to set it up, dress the stone and test it out. It is a bit big for my current lathe, made it for a larger lathe(10" x 22"), my daughter found it for me, only problem it is 9 hours away(Coffs Harbour), will pick it up at the end of March, as I have to go to my daughters then for her wedding.

    Cheers
    Andrew

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  17. Jan 29, 2018 #17

    Ghosty

    Ghosty

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    Hi All,
    After dressing the stone, I done a couple of passes on a hardened shaft. These are 1thou cuts.
    [ame]https://www.youtube.com/watch?v=_5YWDZMRhlA[/ame]

    Cheers
    Andrew
     
  18. Jan 29, 2018 #18

    Charles Lamont

    Charles Lamont

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    Andrew, the grinder is a nice job.

    However, I hope you don't mind a few pointers:

    Old school books would insist you put loads of newspaper or something down to keep grinding wheel grit out of the slides.

    They would also insist on card or blotting paper washers either side of the wheel.

    You appear to have heavily 'glazed' the wheel with the first pass. I would suggest the cut was much too heavy for that wheel, especially without coolant.

    I get the impression the wheel is too fine a grit for the job.

    Another suggestion, if the grinder is mounted on the topslide, is to set the topslide to, ideally, 5.7 degrees, then one division the topslide dial will give an infeed of 1/10 as much.
     
  19. Jan 29, 2018 #19

    Blogwitch

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    After watching and reading your previous post, I was going to suggest exactly the same as Charles, all his suggestions are spot on, plus, you should be working to tenths rather than thous, plus I see you have tried both directions of lathe rotation.

    Here is a little diagram that describes the rotation thing.

    [​IMG]


    John
     
    Last edited: Jan 29, 2018
  20. Jan 29, 2018 #20

    goldstar31

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    Chaddock in his write up on his Quorn quotes a quarter thous as a whopping big cut.

    I've already ticked my agreement with Charles' comments
     

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