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  1. #286
    Join Date
    Jul 2008
    Location
    near Warragul, Victoria
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    3,718

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    Did you use any coolant RC ? Or do you do dry grinding ?

  2. #287
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

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    It was dry. It was a CBN wheel so the cutting heat went back into the grinding wheel rather then the work. (CBN absorbs heat very readily)
    Gold, the colour of choice for the discerning person.

  3. #288
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

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    Trying to find a suitable wheel for a reasonable price for grinding cast iron has led me to flywheel grinding wheels.

    These are cup shaped and have grades designed for cast iron. They are silicon carbide in an unknown grit, made in the USA and even purchased locally not as expensive as you might think.

    Have given it a test run and yes while the workpiece will heat up it is quite successful.

    At the moment I have the knee of my Jafo FWD25 mill in a thousand pieces as I was trying to find why the rapid travels never worked (it has an electromagnetic clutch deep in the innards that has a burnt out coil). Isn't USSR engineering design wonderful? It is easy to pull apart, just you need to pull apart a lot of things to do simple things.

    Anyway the knee on the Jafo mill is pointing up at the moon way way way beyond tolerance levels to the point it is impossible to face mill with it as moving the table for another cut and you have a noticeable ridge where the two runs of the face mill meet. So while the knee is empty I have decided to grind it back into tolerance so the mill will at least be usable.

    Also bought a dust extractor today to use on this grinder to try to suck up some of the grindings, otherwise it goes everywhere.

    20160311_093204.jpg
    Gold, the colour of choice for the discerning person.

  4. #289
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
    Age
    72
    Posts
    3,102

    Default

    I'll be watching your porogress Richard. Keep taking photos
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  5. #290
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

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    Might be less progress then you think Joe, I have the saddle off the mill, so I put my square on the knee and butted it against vertical ways, and the knee itself is squareish for a used machine. So I think the problem must be on one of the upper bits. Will take some more investigation to sort out.
    Gold, the colour of choice for the discerning person.

  6. #291
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    I finally got around to rebuilding the air ram that was retrofitted by previous owners to the machine. The idea of the air ram is to replace a large counterweight that holds the grinding head up and makes downfeed very accurate. It runs at a low pressure of only around 250-300Kpa.

    The previous owners made it all out of steel and it was very nastily corroded and pretty much seized.

    I have rebuilt with all non-corrosive materials

    Facing off the base to fit a stainless steel cover.

    20160625_161208.jpg

    The barrel is made of brass. The end cap made out of aluminium, the rod out of stainless steel and the piston out of plastic.

    20160704_183648.jpg

    Partly assembled

    20160704_202452.jpg

    Installed

    20160704_205015.jpg

    I have also picked up a VFD to power the spindle so I can run it at slower speeds to do very light face milling work. It is a Delta vector control one. I have been playing around with the settings to try to get decent torque at around 1000-1400rpm.

    You seem to be able to set the maximum voltage and frequency, a middle voltage and frequency and a minimum voltage and frequency. I have the maximum voltage a frequency set at 440V and 60Hz.

    Middle at 230V and 20Hz,

    and minimum at 60V and 10Hz.

    I am getting good torque at around my milling speed of 20-25Hz. At factory settings there was no torque at those frequencies.

    I do not know if anyone else has some knowledge on setting up these sorts of things.
    Gold, the colour of choice for the discerning person.

  7. #292
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

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    I have milling capability of sorts now. The VFD had other settings I changed and with themotor running at 1000rpm with a 63mm face mill with sharp inserts, a 0.25mm cut is no problem. To take that much off through grinding would create large amounts of heat and take a long time.

    20160708_131902.jpg
    Gold, the colour of choice for the discerning person.

  8. #293
    Join Date
    Jun 2011
    Location
    Australia east coast
    Age
    71
    Posts
    2,713

    Default

    Quote Originally Posted by .RC. View Post
    I have milling capability of sorts now. The VFD had other settings I changed and with themotor running at 1000rpm with a 63mm face mill with sharp inserts, a 0.25mm cut is no problem. To take that much off through grinding would create large amounts of heat and take a long time.

    20160708_131902.jpg
    A 75mm cutter would have been better - as you'll realise when a certain crate arrives.....

    PDW

  9. #294
    Join Date
    Aug 2008
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    near Rockhampton
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    6,216

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    Quote Originally Posted by PDW View Post
    A 75mm cutter would have been better - as you'll realise when a certain crate arrives.....

    PDW

    I think I have a couple of 80mm ones here doing nothing. Trouble is the surface speed gets a bit fast.
    Gold, the colour of choice for the discerning person.

  10. #295
    Join Date
    Jun 2011
    Location
    Australia east coast
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    71
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    2,713

    Default

    Quote Originally Posted by .RC. View Post
    I think I have a couple of 80mm ones here doing nothing. Trouble is the surface speed gets a bit fast.
    Yeah I understand. I burnt the tips off some inserts when I was too lazy to slow the B/port down. Made some nice sparks though....

    PDW

  11. #296
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    I have put the 80mm on the grinder, and have the motor running at 800rpm down from it's normal 2900rpm. There is a surprisingly amount of torque even at that slow speed. There is an amp meter on the VFD so I know not to exceed the 2.7 amps the motor draws at full load.

    Here is a video of the face mill, milling one of PDW's 36" straight edges.

    https://www.youtube.com/watch?v=AKLhhZ2WVGc

    I could take up to a 0.5mm depth of cut on the smaller 600mm straight edge without bogging the face mill down too much. Finish is superb and I think grinding it will achieve better results, since it is only going to be scraped a 0.01mm error or less from milling is not much to sort out by hand scraping.
    Attached Images Attached Images
    Gold, the colour of choice for the discerning person.

  12. #297
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    Jun 2011
    Location
    Australia east coast
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    71
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    2,713

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    Nice one. Given the time I spent scraping mine in from the planed condition, that's a vast improvement.

    You could have reduced the flange width on the big one without dramas - I only made it that wide so I could spot the full width of the flat ways on the Kearns O type HBM. I've milled one of my 630mm dovetail ones narrower to spot the Monarch cross slide ways.

    Perhaps I should ship you a few more - I've a pile of them waiting for me to get the planer back in working order.....

    PDW

  13. #298
    Join Date
    Aug 2008
    Location
    near Rockhampton
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    6,216

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    I finally got around to finishing off making an angle plate for the borer.

    It is a knee off an old scrapped milling machine, that I have milled bits off itand made it a big square. Today I set it up on the grinder and milled it square. It was set up in the photo, and you can see the 20" square hanging off one end and I am indicating off it to get it ready for milling.

    20160910_144131.jpg
    Gold, the colour of choice for the discerning person.

  14. #299
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
    Posts
    5,945

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    Nice to see bits of older/wornout machinery being converted to useful accessories .
    Kryn
    To grow old is mandatory, growing up is optional.

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