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  1. #61
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    Got to find a time when I can sit back and read this all looks great Michael

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  3. #62
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    Oct 2011
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    Ah! the joys of the two steps forward, one step back approach.
    The weekend just passed the other half decided that she needed to get away which meant of course that I was going too...
    However, for some time I've been meaning to mount and wire in the VFD I have for the grinder, so managed to do that one night before leaving. I did start a thread asking how a VFD could be mounted but apart from either "as per manufacturer's instructions" or "a completely dust proof enclosure", I didn't get much in the way of different ideas so I came up with this -
    P1020392 (Medium).JPG P1020393 (Medium).JPG
    There is a cut out in the front to allow panel access but the main part is in a (bottomless) lidded box - the theory being that when not in use the lid (being closed) should prevent dust settling on the unit. Some light dust may float up into the box but that stuff is going to be so small that the first time the fan turns on that should be blown away (I hope). I may have to paint it as in line with my personally invented law of welding, the good looking welds are where they can't be seen. The daggy looking welds are on the visual surfaces. The wrapper is made of 4 pieces of Al because as could be predicted for a race against time job, I didn't have one piece of material that was long enough
    I am yet to wire up the remote start/ stop buttons, but using the buttons on the panel it powers up and runs.
    Oh Bugger moment no. 1
    I calculated the size of the missing motor pulley based on the motor name plate speed. Of course, this is the rated speed at load not the unloaded speed. According to the tacho, I'm spinning at 2.5% over the maximum speed for the wheel - currently I have VFD turned down to compensate but was hoping to get the size right for the "natural" frequency of 50Hz.
    Oh Bugger moment no. 2
    The belt is an old M series belt - came with the grinder and is not cracked or anything like that so I decided to use it. It also meant the pulley on the spindle would stay as it was. Turning the spindle over by hand, the belt does not have a uniform stiffness to it - what this means for the finish I am yet to find out but I'm now thinking that a new belt is needed. Trouble is, classic M series belts are not all that common these days. Combining OBM1 and OBM2 I'm now thinking that perhaps a poly V belt may be the go - more flexible, easier to find. The spindle pulley is buried within the column though so dis-assembly is now a possibility.
    Oh Bugger moment no. 3
    Having sorted out the drive I thought that I should reassemble the traverse so that I could try the grinder out in anger (actually the first thing on the list is the washer test so I can see if the chuck needs grinding, but you get the idea). I got the helical gear out that I'd made especially for that purpose and discovered that it didn't fit the rack. When I calculated out the cutter I needed I divided rather than multiplied. OB I though - still I can make up another. Looked up the ratios needed to generate the helix and it called for an 86t gear for the dividing head. Anyone want to guess which gear out of the set of 12 I didn't make because it was only used to divide really uncommon numbers? Of course, it's a big one too so making it is going to require me to either pay a silly amount of money for an 8" disc of 5/8" plate or spend a lot of time making it out of segments.

    Where would we be without these opportunities for developing or practicing our skills?

    Michael

  4. #63
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    Melbourne
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    Quote Originally Posted by Michael G View Post
    the theory being that when not in use the lid (being closed) should prevent dust settling on the unit
    Little late now but, how about making the lid 3/4" bigger all round and moving it up 3/4"?
    Then you wont need to remember to open it.

    Oh Bugger moment no. 3 is the reason I haven't bought a gauge block set with some missing blocks, I just know with my luck that will be the block I need.

    Stuart

  5. #64
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    Oct 2011
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    Quote Originally Posted by Stustoys View Post
    How about making the lid 3/4" bigger all round and moving it up 3/4"?
    Then you wont need to remember to open it.
    I did think about something like that but thought the heavier dust particles would be able to drift through and possibly land somewhere. Another plan I thought of was a U or S bend arrangement so that there was no line of sight for dust settlement (the VFD has it's own little fan, so convection is forced anyway).

    Michael

  6. #65
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    Jan 2011
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    I am still thinking about the housing for my lathe VFD and others to follow. I have been running a machine a work which has filters for the inlet and outlet air vents in the computer cabinet. The chief fellow from maintenance just happened to be walking thru one day a couple of weeks ago. Probably because that was the way to go to get to their work/office etc area. I asked him about the filters. They were made by a well known company. His reply, they were a bit expensive, but the filter itself was just a bit of polyester wadding about 6mm thick. Nothing else. SWMBO has shedloads of it. I am thinking of having a computer fan to push air out. I was thinking of doing just what Stuart mentioned except I was going to have a hole cut in the top and a plastic rectangle raised above it. Current thinking is to have a steel meshed hole in rear panel, with inlet at the bottom and outlet with the fan at the top. Maybe a bit of a baffle to confuse the air.

    Unfortunately thinking is about all I get time to do at the moment. I have had quite a long run of working in the shed for myself. Time to do some stuff I apparently promised to do. Not to mention stuff that has to be done now!

    Dean

  7. #66
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    Aug 2011
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    Melbourne
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    Hi Michael,

    Looking good. Sorry to hear about the gear! 2 steps forward, 1 step back: I know the feeling!

    I have been running my VFD for my mill with it just mounted on the wall, no housing, no dust prevention. I will be interested to see if I will eventually pay the price for that!

    For those who want forced air cooling through a filter in an enclosure, what's wrong with a simple automotive filter? You could probably use the old one from your car when you next get it serviced. Or, if you go to one of those Doof Doof shops you could get an aftermarket one with a round take up. Making it easier to mount. You may even get more power out of the VFD!

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  8. #67
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    Jun 2011
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    Australia east coast
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    WRT the M belt, I got a replacement in Hobart easily enough and Adelaide should be a hotbed of industrial suppliers in comparison. I *may* have a spare rack gear too, can't remember ATM. I'll be home around the 10th August so if you're still stuck let me know. I'm looking forward to bolting down my nice new 10x5 mag chuck and sharpening my jointer blades. PDW

  9. #68
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    Oct 2011
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    Quote Originally Posted by simonl View Post
    For those who want forced air cooling through a filter in an enclosure, what's wrong with a simple automotive filter? You could probably use the old one from your car when you next get it serviced.
    It might work but remember you have a pretty fierce positive displacement pump pulling air through those normally. For a fan a piece of the polyester material that Dean mentioned would have far less pressure drop and be almost as effective I would have thought. For a VFD it's the volume of air flowing that is the important bit.

    Michael

  10. #69
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    Quote Originally Posted by Michael G View Post
    It might work but remember you have a pretty fierce positive displacement pump pulling air through those normally. For a fan a piece of the polyester material that Dean mentioned would have far less pressure drop and be almost as effective I would have thought. For a VFD it's the volume of air flowing that is the important bit.

    Michael
    The air cleaner from my old car is sitting on the verandah at the moment. It is s flat type. I thought about using it but decided against it for the above reason and because it would be harder to fit. The plan for the poly is to just sandwich it and some light steel mesh between 2 boards which have a hole (or 2) cut out. A few screws to hold them together. I also plan on some outer physical protection. For the cost of a car air filter, when it requires reploacement, you could buy a lifetime supply of poly for the entire workshop. You can buy quilt packs in various thicknesses. How many bits could you get from a king sized quilt?

    Dean

  11. #70
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    Oct 2011
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    Default Powered up and ready for the grind (well, sort of)

    Work and life got in the way a bit here but I finally ground some steel on the Power SG today.

    The main stumbling block was making up the gear for the traverse rack and pinion. After many tries I have discovered that while there are complex formulas for cutting helical gears so they have a correct profile, cutting a helical gear to mesh with a straight rack requires you to pretend it is a straight spur gear. If I'd realised that that 6 gears ago...
    Anyway - made that up today and fitted it up to the new traverse shaft. In keeping with the age of the machine I pinned the gear to the shaft with an imperial taper pin - I bought an assortment of them because they are always one of those things that you can never find when you need them. If anyone needs one let me know (I also have a couple of reamers to suit if necessary).
    Once I had that "minor detail" sorted I attached the spark guard and mag chuck, found a wheel, mounted that and I was set. I certainly see it as an improvement over what I bought (2nd photo) although the basic machine was reasonably sound (just filthy and missing some bits).

    P1020587 (Medium).JPG Grind 1.JPG

    What I should have done was then dressed the wheel but I was impatient to see what the grinder was doing, so I launched into the 5 washer test. For those not familiar with this one (or this name) you literally put 5 washers on the mag chuck and take a lick off them, making sure you get full clean up on all of them at the same height setting. These washers were punched, so I cleaned up the burr side and then flipped them over and ground the other side. I blued the faces with a texta so I was sure that it cleaned up. Note the way that the punched edge has pulled the corners down.

    P1020588 (Medium).JPG P1020591 (Medium).JPG

    The results were not bad - across the back both washers measured 60.3 thou, across the front 59.9 thou, so 4 tenths different front to back and nothing side to side. The centre washer measured 61.1 thou though, so there is a 1 thou dip in the middle of the chuck. Once I have some coolant sorted I'll grind the table and hopefully that will fix all of those issues. (It does annoy me though that an expensive item like a mag chuck is (although slowly) consumable tooling!)
    Even with an undressed wheel according to my surface roughness meter I was getting a finish of Ra=0.48 um which the internet says is a typical "average" finish for grinding so with a dressed wheel and coolant I expect that I should get even better finishes from it.
    Now that it is functional I'm hoping I can use it to make bits for the other grinder as well as make up some jigging so that I can use it to grind tooling. First back to the mill though to make a holder for the dresser.

    Michael

  12. #71
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    Aug 2008
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    near Rockhampton
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    Very nice...

    Another fine Australian made machine tool back in operation...
    Light red, the colour of choice for the discerning man.

  13. #72
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    Aug 2010
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    Well done Michael!
    And thanks for sharing the experience.
    Cheers,
    Joe
    9"thicknesser/planer, 12" bench saw, 2Hp Dusty, 5/8" Drill press, 10" Makita drop saw, 2Hp Makita outer, the usual power tools and carpentry hand tools...

  14. #73
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    Oct 2007
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    Michael did you grind the chuck first? It doesn't look like it's been ground. Before doing any tests it would probably be worth giving that a lick as it may not be parallel to begin with.

    Once that's done I'd try repeating the test and in addition try grinding the opposite way and see if it repeats any error. It's unlikely you'd have much wheel wear on just 5 washers, but that would eliminate that potential error anyway.

    Pete

  15. #74
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    Quote Originally Posted by Pete F View Post
    Michael did you grind the chuck first? It doesn't look like it's been ground. Before doing any tests it would probably be worth giving that a lick as it may not be parallel to begin with.
    No - I got impatient
    I will grind the chuck but I was interested to see how bad it was and whether there were other issues that would be detrimental (eg side to side being worn at one end) I want to get the coolant side sorted first before I grind the chuck as there was not much heat in the washers but a chuck may be different. Once the chuck is ground I will repeat but would expect things to be almost spot on

    Michael

  16. #75
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    I'm not sure the test you did will actually tell you much then I'm afraid, other than surface finish of course. While it's likely the chuck is reasonably accurate, until it's ground parallel, at these levels any error in the chuck will show up as an error in the test. The machine could be perfect. On the other hand both the machine AND the chuck could be in error. Or, sadly, the chuck could be perfectly mounted and the machine in error. Alternatively any combination of the 3 conditions.

    I saw that chuck at your place, but didn't look at the bottom. If the base is looking a bit rough around the edges I'd flip the chuck, and turn it on to the casting. It should only need a lick. Then mount it and grind the top. It shouldn't need much off and there's always heaps of meat in these things from what I've seen. They're designed to be ground periodically. I wouldn't be surprised to see your washer test come down once that's done.

    I'll be keen to see how you get on with coolant. With a similar sized machine it's something I'd like ... along with power traverse and feed

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