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  1. #31
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 11 Hours Ago Has been a member for 3-4 years. Has a total post count of 685. Received thanks 97 times, giving thanks to others 5 times.
    I cheated a couple of days ago when I needed to tap some M8 holes in a slab of Ecocast I had just drilled. I held the M8 spiral-point tap directly in the drill chuck, and took off the drive belt on the mill (Warco VMC with multi-speed belt drive so easy to do). I could then turn the drive pulley by hand. Light down pressure on downfeed handle, and this was enough to get a good thread started, finished by hand later. For small taps, I have lightly guided them in the chuck jaws and tightened a tap wrench on to the shank (not square) of the tap to turn them. Especially with these easily-driven spiral-point taps, this works ok to get a thread started. But I'll have to have a look at the RDG tap holder the next time I see them at an exhibition - thanks.

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  3. #32
    Hi Neale,

    Yes, done something similar to that by slackening the motor / belt tension levers on the drill press. But even with the belt slack there is still quite alot of friction and it still tries to turn the motor.

    To remove the belt on my Warco pillar drill completely takes a bit of time and involves a ladder, a screwdriver to open the lid, and releasing the motor bolts and is not very efficient. It's not much fun for long due to the effort of turning the chuck & motor.

    The method above is quick to set up (just a quick adjustment on the chuck jaws) and is then very easy to turn.

    One thing I will note is that the tap slipped occasionally, even though I tightened it as much as I could. I don't know if they do a keyed chuck version but that might be better. Maybe a bit of degrease on the inside of the chuck jaws would help. Next time I'll also try a tap handle on the round part of the tap shank as you did.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  4. #33
    Bit more progress. One of the gantry end plates was cut out over the weekend:
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    Tonight I drilled and tapped all the various holes. Couldn't resist a trial fit of a couple of the previous parts:
    OUTER VIEW
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    (Note the tabs on each end still need facing off. I'll wait for the other one to be machined then do them in the same session.)

    INNER VIEW
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    With the side plates offered up:
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    Another reminder of what the end sections should look like . ..
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    I used the tapping chuck again which made light work of the threads. Also discovered I was holding the tap wrong. I had been putting the tap right into the chuck and it gripped on the round shank - liable to slip. Looking at the 3 jaws of the chuck I noticed that it has ridges in the centre of each jaw. If you put the square part of the tap into the chuck these grip the 4 sides nicely, with 2 jaws on the flats and 1 jaw (with the ridge) on one of the chamfers of the square. Hard to describe but just put the square shank of the tap into the 3 jaw chuck and it will not rotate.
    Last edited by routercnc; 11-04-2016 at 09:59 PM. Reason: tidied up
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  5. #34
    Wow!
    This looks like a masterbuild!
    I love it when its over complicated ;)

    Fancy, funny and fantastic!

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  7. #35
    Very nice,
    Looking forward to seeing this finished.
    Mike

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  9. #36
    An update on the next bits on the list - the gantry lower bearing plates. I need to make 2 mirrored parts, here is the first one progressing -

    Setting up and cutting some slots. These are to adjust one of a pair of ballnut brackets. I'm going to run 2 ballnuts pre-loaded against each other:
    Click image for larger version. 

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    The other holes have been spotted (to finish on the drill press) and the profile cut out. I tried something a little different to try and get the profile size as good as possible. As this sits on the X bearings I want this to be a datum part during the build. The rough profile cut was +1.0mm, then another rough cut at 0.2mm, and finally a finish cut at 0mm. You can see the finish in the photo which is excellent. I'll check with calipers how accurate the overall size came out.
    Click image for larger version. 

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    I've yet to drill out the holes on the top, and there are lots of holes required in the sides, but I thought I'd try a quick fit to make sure all was well. No bolts yet just propped together but looks good!
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    Here is the start of the one for the other end. I had to line this one up using a DTI and get it very accurate to avoid hitting the holes in the donor plate I'm using. I've cut the slotted holes, next up will be spotting and profile:
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    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  10. #37
    Also, I'd made a few design changes a while back but hadn't posted them so here they are.

    1. Z axis
    -Twin ballscrew instead of single
    -Main body machined from solid
    -Upgrade from 15mm miniature rails to 20mm Hiwin
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    2. Y axis
    -Double ballnuts, one fixed ballnut housing and one floating housing to allow pre-load to be added
    -Simpler bracing pieces
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    3. X axis
    -Double ballnuts, one fixed ballnut housing and one floating housing to allow pre-load to be added
    Click image for larger version. 

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    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  11. Twin ballscrews on the Z - should be able to punch the cutter through the work with the motor turned off !

    :)

  12. #39
    Cheers Dave !

    It might do that yes, but it is still one stepper motor so it's not any more powerful than before. Reason for doing it is that it should help reduce vibration as both sides of the Z axis are held when machining, not just one side.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  13. Following with interest ;)

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