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  1. #151
    Dave J Guest

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    I think once you cnc it, I don't think you would use it manually, you could have a pot connected to a hand wheel be able to control it up and down by that. Just like manual but it would be electronic. I see these on a few cnc's to move the table etc.

    If you do have to disconnect it you could do as you say and undo the nut, jog it up a bit so it was clear. To stop the accidental problem of the ball screw going through the nut when undone, you could have a washer larger than the screw and a nut holding it on, up on top of the quill clamp as well as the bottom one. Just turn down and tread a bit extra of the end of screw to allow for the extra nut.

    Casting sounds interesting, I want to get into that myself. I will be watching out for posts on that.

    Dave

  2. #152
    Dave J Guest

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    Hi Ray,
    Thinking about it, instead of the washer and nut I talked about above, I think it would be better to make a threaded washer/spacer on top of the casting (in red) that way when you undo the bottom nut the screw can not go up through the ball nut.
    Depending on the size of it, it could also help with any flexing between the screw and the casting your going to make.

    Dave

  3. #153
    Join Date
    Jun 2008
    Location
    Victoria, Australia
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    74
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    I got a bit of time to do the VFD spindle conversion, after deciding to use the MESA 7I47S I/O card for spindle control, I have ordered one, but delivery will be in October, so in the meantime I want the ability to manually override the automatic control anyway.

    A PDF of the preliminary circuit design is here ... http://www.backsaw.net/pics/HM52_Spindle_Circuit.pdf

    The circuit diagram contains notes on modifications required to the HM52 wiring.

    The motor I got was a 1.5kw TECO (from ebay) and the VFD happened to be a TECO FM50 (again off ebay)



    The shaft diameter and keyway was the same as the original motor, which made things a bit easier.

    The flange mounting bolts are the same on both motors, it's a standard 90L frame but the spacing and bearings are different, so I have to make an adaptor plate.
    This was cut from 1/2" aluminium plate on the bandsaw and finished by hand (no mill you see!)


    The flange on the teco interferred with the mounting bolts so I had to grind a bit off the flange to clear the washer.



    The finished adaptor plate, the colour is "sky blue" to match the H&Fcolour scheme..


    I cleaned the motor and primed it with Galmet and then painted it to match.



    VFD temporarily mounted on the wall, The new control panel will go on the front of the machine, where the H&F nameplate used to be. This frees up the side of the Quill for the Z axis.

    The front panel will have a RPM display which will pick up the spindle speed directly from the spindle itself, so that when adjusting speeds
    the belt configuration is automatically corrected for.

    Regards
    Ray

  4. #154
    Dave J Guest

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    That came up looking factory fitted Ray, but I expected that from you.
    What type of spindle rpm display are you going to use?

    Something I plan to do is to make a collar to go around the motor adjusting nut, with a grub screw to hold it onto the nut and a 100mm x 12mm round handle welded off it. That way you don't need a spanner to adjust it for belt changes, which is always a pain.

    I see you have found the super cheap paint match's nearly perfect with the H&F blue. I colour matched up a litre of the creamy colour, took me hours to do it as it has a slight hint of green as well as many other colours in it. It has matched the mills I have had here, so it should match yours. If you want some for touch up's I could send you some.

    I don't know how you go in your shed for rust, but I have troubles in mine in the winter. The table covers take care of the top, but keeping up with the sides is a pain.

    I haven't done this to the current machine, but what i did on my old machine is to use those spray cans to paint the back of the table/saddle, the front of the saddle and the ends of the saddle and table with the blue (this time it will be red). It saved having to worry about looking after those surfaces from rust.
    After painting it makes it look like it came that way and none of those surfaces need to be bare for any reason.
    It doesn't harm anything doing it, when I returned the first mill, I removed the paint and it came off with a razor blade and a bit of thinners in the cracks. I didn't use any undercoat under the blue, and it held up fine.

    Dave

  5. #155
    Join Date
    Jun 2008
    Location
    Victoria, Australia
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    74
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    Hi Dave,

    Thanks for the offer of the paint, I would like to reserve a bit of that paint for when I get to the final cleanup stages.

    Rust isn't too bad around here, I get a little bit of condensation on really cold mornings on the roof trusses. But generally it's pretty dry.

    The spindle rpm indicator is going to be a custom design. Probably based on this
    PIC24F Starter Kit Learn PIC24F 16-bit MCU Programable - eBay Power Amplifiers, Amplifiers, Audio, Electronics. (end time 20-Aug-10 14:01:55 AEST) and a bit of custom hardware.

    Regards
    Ray

  6. #156
    Join Date
    Jul 2006
    Location
    Athelstone, SA 5076
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    4,255

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    that look good Ray

    I just opted to replace the plate on the Mill with some alloy and slot it

    I am only having one section V belt pulley on the motor so wont need the plate with handle for belt adjustment....once adjusted it should be ok for ages till the belt needs adjusting

  7. #157
    Join Date
    Jun 2008
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    Victoria, Australia
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    Finally getting back to the CNC conversion..

    Started making the pattern for casting the bronze mounting block for the Z axis mount.

    DaveJ posted the idea of fixing the ballscrew and driving the ballnut, so this is based on that idea.

    Z Axis Quill drive concept.



    The aim is to make the whole assembly as rigid as possible, while getting as close to the axis of the spindle as possible... The AC bearings as drawn are not the right size, but the concept is the same.

    Regards
    Ray

  8. #158
    Join Date
    Jun 2008
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    Victoria, Australia
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    74
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    Z axis progress update,

    After playing around with dozens of variations of different ways to do the bearings, I finally settled on NSK 7912A5 AC bearings and housed in a cast mount.

    Here is the general arrangement



    The quill return spring stays, but with a different spring, tensioned to just balance near the top of the travel. The back of the ballscrew bearing mount is cut out to accomodate the quill return spring.


    I still have to make the core molds, and the parting line will be centered on the axis of the main bearing. The quill spring cutout will be filled in before casting, and machined out after.



    The center of the quill clamp need to be built up before casting, to accomodate any shrinkage, and then machined to finished size afterwards.
    Material will be aluminium bronze.

    The side of the mill where the bearing mount is going to go is dished and the next job is to try and flatten it as much as possible..



    I've got most of the bog off and now trying to come up with some way of flattening it..

    Regards
    Ray

  9. #159
    Join Date
    Jul 2010
    Location
    Melbourne
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    9,088

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    Hi RayG
    Couldnt you bolt it to the table and use the Hoz spindle? Or aren't you after that flat?

    Stuart

  10. #160
    Dave J Guest

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    Thats looking great Ray,
    It would be a bit of work, but you could take the head off and separate the belt housing so you only have the head housing, then use the horizontal spindle to do the clean up to get it flat.
    It might pay off, as you would be able to get it parallel with the quill bore so you ball nut housing will sit flat and parallel.
    Will look forward to your up dates.

    Dave

  11. #161
    Join Date
    Jun 2008
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    Hi Dave and Stuart,

    The more I think about it the more I like the idea of machining it using the horizontal.
    That way I can make sure it's nice and flat, and the bearing housing won't wobble or twist.

    The other attraction, is that gives me a chance to have a close look at the spindle bearings, like Dave has done. here.. http://www.woodworkforums.com/f65/ch...e-hm52-126514/

    Been looking for an excuse to pull the rest of that apart....

    Regards
    Ray

  12. #162
    Dave J Guest

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    I think the nut being set up parallel to the quill bore would be a necessity for it to work properly and last. When you set up the head on the table, you can set it true using a dial indicator on the bore.

    To get the top belt housing off, there are 2 taper pins and 4 bolts under the quill pulley that joins it to the main housing. To get the pulley off after undoing the nuts, just use a small crow bar to lightly lever the pulley up, then turning 1/4 of a turn and repeat until it loosens off it's taper.
    I found it easier to undo the 4 bolts on the ram to get the head off as the worm gear is attached to the head which goes inside that collar.
    Taking this off will give you a chance to clean the worm and gear, mine had shavings in their. I also added a few washers each side of the worm, on the worm shaft to take up the back lash it had when tilting the head.

    Dave

  13. #163
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    Jun 2008
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    No sense in waiting around, I stripped the head assembly as much as I could, using the knee to support the spindle and gently lower it out, worked a treat. No need to disconnect the motor wiring, just unbolt the motor and leave connected.

    Thanks Dave for the advice on removing the head, those big 12mm hex bolts have to come off first. The head is trapped by the gear/worm drive that does the head rotation.



    I used the Knee, wound all the way up, and a bit of packing to support the head, and then when it came loose, used the Y axis to back it out of the column. No heavy lifting required. (No swarf in the worm drive either)



    I put the spindle back to use as a reference to tram the assembly alignment to the X axis table. With a DT indicator.



    Lots of light passes, in hindsight, I probably could have done it two cuts, but it's a bit nerve racking watching your mill slowly eating itself..



    At last a flat surface, parallel to the spindle.

    The machining uncovered a few porous patches in the casting, not sure just yet, but a bit of bog seems to be the original manufacturers cure for all these issues...

    Now where do all these bits go?


    Regards
    Ray

  14. #164
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

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    Nice work Ray.... What program do you use to make the graphics like in your above post? "Z Axis Quill drive concept."

  15. #165
    Dave J Guest

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    Wow nothing for ages then you have the hole head apart in one day, LOL
    It's coming along great.
    It's scary at first machining and modifying the machine, but after a while it doesn't bother you.

    It looks like the bottom of your head casting is a lot better than mine, you must have got a mid week one and I got a Friday one.
    When you machined the side, did the face mill leave any ridges top of bottom on the overlapping cut's to show any sign of the horizontal being out?

    I have found they cast everything very close to size, then they only have to machine the minimum off, must be to save money in metal.

    I rebuilt my down feed worm and gear as well but haven't posted it up. I will try to get it up to show you what I did.

    Keep up the great work
    Dave

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