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  1. #1
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    Default Narex VHU36 boring and facing head - how to get facing mode

    I've got a Narex boring and facing head that I've only ever used for boring.

    I'm trying to set it up for facing, followed the instructions in the manual but just can't get it to move from zero feed.

    The instructions say that you need to get the red mark to line up with the feed you want by rotating the knurled ring with the mark on it.
    It goes on to say that the easiest way of doing that is to lock the safety pin into the larger knurled ring, then twist both knurled rings against one another.
    Tried that, but despite almost ripping the skin off my fingers its not moving. I can see very slight play between the silver ring and the smaller knurled one so I know they are separate parts.

    Anybody got or used one that can shed some light on how to do it?

    The safety pin in its disengaged position. Pushing it down engages in the slot in the ring below locking them together



    And then you should be able to rotate the knurled rings to change the feed setting from zero to one of the 3 feeds




    Steve

  2. #2
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    I have one the same but not the same maker. It works just as your instructions say. Push the clutch pin down then turn the 2 knurled rings against each other to set the feed number. Hold the top knurled ring while the head is rotating makes it feed out. If you set the stops the clutch pin will pop back up at the end of travel. If you lock the cutter holder with the knob that has the 4 holes in it then it won't feed outward, that needs to be loose.
    Hope that makes sense. If yours won't let the numbers move when the pin is engaged then there must be something else stopping it.

    edit
    The 2 knurled rings and the number ring are all separate pieces. If the pin is up the number ring turns with the lower knurled ring. A screwdriver in the number rings' slot will hold it while turning the bottom knurled ring. Does yours do that or is the number ring locked against the bottom knurled ring?

  3. #3
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    Thanks for the info.
    The number ring on mine seems locked with the lower knurled ring, but there’s a tiny bit of backlash between the two.

    I’ve given the whole thing a good dose of penetrant and will see what it’s like tomorrow.
    Otherwise I might have to look at stripping it down - which I’m not too keen on.

    Steve

  4. #4
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    Quote Originally Posted by OxxAndBert View Post
    Thanks for the info.
    The number ring on mine seems locked with the lower knurled ring, but there’s a tiny bit of backlash between the two.

    I’ve given the whole thing a good dose of penetrant and will see what it’s like tomorrow.
    Otherwise I might have to look at stripping it down - which I’m not too keen on.

    Steve
    If you strip it down we will need lots of pix. I am very curious how it works but not brave to pull it apart

  5. #5
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    Quote Originally Posted by oldbuggermike View Post
    If you strip it down we will need lots of pix. I am very curious how it works but not brave to pull it apart
    Stefan Gotteswinter stripped a Kuroda head, probably much the same....

    https://www.youtube.com/watch?v=MPPPORn6C7g

  6. #6
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    Default Narex VHU36 boring and facing head - how to get facing mode

    Think I've got it worked out. Here's crop of the exploded parts diagram from the Narex manual: (full manual is here)

    Exploded Parts.JPG

    The ring with numbers (7) is locked to the lower control ring (47) by 2 pins (48).
    The lower control ring has 6 drive pins (12) in my model - but the diagram shows the larger heads which have 8 drive pins.

    Rotating the lower knurled cam ring (9) compared to the ring with numbers causes the cam on the inside to push in opposing pairs of drive pins (12).
    When there is relative motion between the control rings and the star wheel (16) the drive pins cause the star wheel to advance one tooth each time a drive pin goes past it. The star wheel in turn is connected to a worm which drives the leadscrew in the head causing it to move.
    There are 4 positions of the number ring giving 0/1/2/3 pairs of pins engaged (and corresponding radial movement of 0.02/0.06/0.06mm/rev)

    The issue in this head is that what should be a ball (49) and a spring (10) have been replaced with a solid pin and a tiny short piece of hard black material underneath the pin which makes it project into the detent hole for each number.
    It was effectively locking the 2 rings together as it couldn't move out of the detent when I tried to turn it.

    The small black bit is circled in this photo:




    My gut feel is that sometime in its life somebody has pulled the thing apart, lost the spring and ball - and substituted the pin.
    The hard black bit might even be a piece of rubber o-ring that was being used as a pseudo-spring but has gone hard with age and oil.
    It seems to be slightly magnetic though, so I'm not 100% sure what it is yet.

    I just need to find a tiny spring and ball to fix it!

    Steve

  7. #7
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    Nice work Steve.
    Empty cigarette lighters are a good source of springs for this sort of thing and I've got a stash of tiny bearings so give me a yell if you get stuck.
    Cheers,
    Greg.

  8. #8
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    Thanks Greg, it might come to that yet!

    Its been niggling me all day as I know I've come across a bunch of small coil springs recently but couldn't remember where. Finally clicked tonight that it was when I pulled apart the ignition lock in my forklift - the springs that are behind the small moving brass bits in the lock. I can't use those ones but I'm sure I've got a couple of small padlocks around that would be prepared to donate their all for a good cause.

    I checked tonight and the ball and spring need to be 2.0mm OD. I liberated the balls from a couple of small bearings I had here, but no luck - they were 1.6mm and 2.4mm.

    Steve

  9. #9
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    Hi Steve, Guys,

    The circular Yale style locks might have what you need for the springs ! I'm not sure about the balls though, all the yale locks I've dismantled have split brass pins. Though some of the ones with a round hollow key have balls in them.
    Best Regards:
    Baron J.

  10. #10
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    G’day Steve,
    I’ve got a 2mm ball bearing here, can drop it in the post if you like.
    8BE79C89-D5E9-40F4-B869-A1E1B78864D4.jpg
    I reckon a lighter flint spring must be around 2mm but I haven’t got one handy to check.
    Cheers,
    Greg.

  11. #11
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    Found a lock from an old equipment cabinet at work - pretty much the same as your average toolbox lock - a barrel with a small locking arm attached to the back.
    It donated a 1.6mm diameter spring that was a good length.

    Found a small bearing race off an old printer, but the balls were still too big so I decided just to try using the dodgy pin that was there when I pulled it apart. Shortened the pin on the grinder, checked the spring would compress enough to allow the pin to be level with the surface - then put it back together and it now works!
    Easy to turn the feed ring, but it locks into each detent nicely.

    Since it was a bit late to actually machine anything, I made a quick video to show how it works.
    Take it easy on my (lack of) video skill

    Steve

  12. #12
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    Quote Originally Posted by kwijibo99 View Post
    G’day Steve,
    I’ve got a 2mm ball bearing here, can drop it in the post if you like.
    8BE79C89-D5E9-40F4-B869-A1E1B78864D4.jpg
    I reckon a lighter flint spring must be around 2mm but I haven’t got one handy to check.
    Cheers,
    Greg.
    Thanks Greg. I'm OK for now - its working fine as-is but I happened to get to the bearing shop today for something else and was able to get a couple of 2mm balls while I was there.
    Since I haven't put the drive flange or arbor back on yet I'll probably pop the circlip off and fit a ball instead of the pin.

    Steve

  13. #13
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    For anyone interested - this was the job I wanted the facing function for.
    Cutting a counterbore for a repair bush in the transfer case of my Landrover Ute. Had to make a short boring bar and grind up a tool to fit too.
    Pretty happy with how it turned out.





    Steve

  14. #14
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    Quote Originally Posted by OxxAndBert View Post
    For anyone interested - this was the job I wanted the facing function for.
    Cutting a counterbore for a repair bush in the transfer case of my Landrover Ute. Had to make a short boring bar and grind up a tool to fit too.
    Pretty happy with how it turned out.
    Bit late now, but the two I've done I just put the counterbore on the outside with a flat bottomed boring bar, and made the bush a tight fit just slightly below flush with plenty of Loctite used. Once the T-case is attached to the gearbox it can't go anywhere anyway as the gearbox overlaps the bush (well at least with an r380, lt77 or lt85 might be different)...

    Not that it makes any difference, both ways work!

    For bonus points, despite their alternate name, Britpart seems to make the only replacement intermediate shaft that actually comes fully ground after heat treat to exactly the correct factory sizes. On my mates one I went through Allmakes, EAC, and one of the others - none of them had been ground after heat treat, and they were:
    A: Not round (by something like 0.1mm from memory)
    B: Not straight.
    and C: Not even the right diameter, I don't think even your new press would get the bearings to slide on, and as you know they NEED to be a nice sliding fit to actually assemble the thing.

    But both the Britpart I got for mine, and the one I got some months apart for my mate were spot on.

    I also put Viton o-rings in both the ones I did, as they have a higher service temperature. Time will tell if they last any better, but it seemed like a good idea given the LT230 runs fairly hot. Don't remember what the sizes are, but they're an off the shelf size you should be able to order at your local bearing place.

  15. #15
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    Thanks For the info.
    Not sure what brand the one I’ve got here is - but it’s definitely not ground. I’ll check it out.
    First one I’ve done but I have at least one other to do. I hadn’t clicked on the gearbox stopping the bush coming out. Im more familiar with the LT95
    The next ones I do will be counterbored on the outside!
    I also had to face off some reasonable wear on the inside of the rear hole where the nut obviously hasn’t been tightened enough and the bearing cone had worn into the case. That was done with a flat bottom bar through the other hole.

    Steve

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