Anyone familiar with the QCGB on a 610/612?
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    Default Anyone familiar with the QCGB on a 610/612?

    My 612 is working electronically. Main motor, hydraulic pump, and rapid traverse all rewired to 220V and turning. Spindle speed shifting works well. But ...

    My "tumbler lever" on the side of the QCGB on my 612 isn't engaging, so neither the feed rod or threading leadscrew are not turning. This is the lever on the right side of QCGB that is suppose to be flipped down before changing any of the feed gears, and then back up to engage the QCGB after a gear change.

    I took the cover off the QCGB and while the spindle was under power in a very low gear and the end gears are turning. Nothing inside the QCGB is moving. Nor do any of the levers that select range A-B or C-D-E shift as if under rotation.

    I have the parts diagrams from vintagemachinery.org. The tumbler lever turns a small gear at the end of a shaft. But I can't figure out what that gear engages with. I would guess something on the tumbler gears but thats a guess.

    Anyone familiar with this gearbox? I'm asking on the off chance someone has run into this and has a quick suggestion. Likely pulling the QCGB off is in my future, but I may try pulling the faceplate off first. Like everything else on this lathe, the gearbox appears to be a real beast.

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    As you know my model is a Series 61. So outer cover is a bit different, but I think in principle they may work similar. I don't have mine operational, in fact the qcgb is still on the floor . But outer cover looks like this:

    9.jpg

    With outer cover off, there is a thick heavy plate inset to the surface of qcgb. Moving the right lever moves that plate up and down like a guillotine blade. That lever is attached to a shaft with two gears. Those two gears only contact that inset plate:

    353.jpg 354.jpg

    That inset plate that moves up and down has notched slots typical of a qcgb. I have not gotten to the point where I fully know and understand this particular mechanism. Here's some more pics, the last appears I have a fork not in line with an internal tumbler lever.

    355.jpg 356.jpg

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    Quote Originally Posted by texasgunsmith View Post
    As you know my model is a Series 61. So outer cover is a bit different, but I think in principle they may work similar. I don't have mine operational, in fact the qcgb is still on the floor . But outer cover looks like this:
    Looks very similar externally. I'll take the front/outer cover off of mine before removing the QCGB and see what I can find. THANKS!!
    Ironically I just today put the QCGB back on the lathe on my 10EE.

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    Well, I found the problem.
    Both pieces were in the bottom of the gearbox. The cracked off piece of the tumbler casting is shown sitting almost in place in the first picture, and the pin that engages in the slots and is pushed up and down by the "guilotine", as texasgunsmith aptly called it, is shown in the second.





    Obviously this had been repaired (poorly) before. Mostly pinned with some attempt at some brazing tacs.

    texasgunsmith,
    If you look at my first picture, thats not a out of place fork. Its just that the cone gear inside the gearbox has an out of sequence gear so the corresponding notch is lower for the larger gear. Note the numbers across the top of the threads per inch plate in your first picture go from ... 6, 7, 8, 9, 5, 10, 11, so the gears are not in sequence by size, 5 is out of place. Yours and mine are identical in that feature. I have no idea why they did it that way. On another note, I'd be curious to know if you see any way to pull that tumbler out that might work without pulling the gearbox off the lathe. Obviously the shaft that goes through it needs to come out.

    If you're familiar with an older style QCGB with a tumbler lever (such as the CK, CY, CW series), this accomplishes the same thing in two steps. The lower dial moves the tumbler left or right to match up with a gear on the cone gear, and the lever on the right side does the equivalent of raising or lowering the tumbler so the gear engages. The 10EE uses a very similar mechanism. Didn't really figure it out myself until I was able to run this lathe with the front cover off of the QCGB.

    Now, I figure I need to either find another tumbler, or I could try to machine off the top of the casting and make captive piece out of steel and use a couple of cap screws to bolt it on. I think my first step will be to contact Monarch next week and see what if they either have a 2nd hand part and/or can tell me if any other models use the same size part. Looks very similar to texasgunsmith's model 61 but they may or may not be an identical part (tumbler).

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    I'll need to take a peak at mine to see if I can determin.

    May or may not be identical, but a fella named Mike was parting a Series 60/61. I bought from him and it went very well. Also he has the lathe in a million pieces I believe. He might be able to give you some measurements to see if its close, might go right on, maybe some minor modding, who knows. But his thread is here if you want to pm him:
    Parting out Series 60/61 16 by 54 lathe

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    It appears to me that you do not need to remove qcgb. The through shaft should pull out from the left end of lathe, the gear train side.

    On mine note that white end cap with 4 allen screws holding it, the screw driver pointing towards it:

    367.jpg

    That white cap is covering the end of the shaft, dont know whats under the cap.


    Prior to removing qcgb, there was a two gear assembly I removed. Those gears may be in the way to get cap off. You can see the gears are attached to an adjusting bracket.

    361.jpg 362.jpg

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    One spot that may be difficult is the bearing on shaft. How it comes off, and not destroying it. It has to come off if shaft can slip out left side of lathe.

    363.jpg

    Some pics of my tumbler:

    364.jpg 365.jpg

    The back side of qcgb is solid. There is a plate bolted to bottom of qcgb, heard of some leaking and needing a reseal, but dont think it will help here. If for some reason shaft can not go out left side, then I think it turns into a bigger project. You would have to pull right side cover from qcgb. Here's a partial glimpse with that cover to left side of pic, but I think it wont need to go that way.

    366.jpg

    Edit* Looking at the parts picture for mine, that bearing may be a problem. Part number L61, the taper of cone bearing is oriented in a not fun way. Maybe its just the pic, not the reality. Just not sure how tight the bearing is pressed to shaft also.

    Interesting oddity though, look at the other cone bearing, L46, taper in the same direction. Somethings wrong with the pic, cone bearings need to have taper opposite way in any application I can recall.

    Re-looking my pic of bearing, I'd wager the large end of cone bearing is to the inside, so hopefully not terrible.

    368.jpg

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    For reference, mine is 4.5" from shaft to outer edge of tumbler cast, not the tit. Shaft diameter 1.25". And the tumbler cast is about 2 1/8" wide.

    Edit* Also about 2 1/8" from shaft to the center of tumbler gear's shaft. with that internal shaft about 3/4".

    Difficult to get a gear diameter, in the vicinity of 2 3/4 to 3". If you need a tooth count on that gear, I can probably work it out, but i didn't get it to roll with it engaged, I'd have to sort that out .

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    Quote Originally Posted by texasgunsmith View Post
    For reference, mine is 4.5" from shaft to outer edge of tumbler cast, not the tit. Shaft diameter 1.25". And the tumbler cast is about 2 1/8" wide.

    Edit* Also about 2 1/8" from shaft to the center of tumbler gear's shaft. with that internal shaft about 3/4".

    Difficult to get a gear diameter, in the vicinity of 2 3/4 to 3". If you need a tooth count on that gear, I can probably work it out, but i didn't get it to roll with it engaged, I'd have to sort that out .
    That matches mine and the one Mike has. He's going to pull it out of his and send it to me. Looks like I'm in luck. Fingers crossed.

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    Ended up taking the QCGB off, just looked to complicated to try through the front. Can't remove the plate on the QCGB that faces the apron without pulling the gearbox, as two capscrews are set back into the lathe bed, much like a 10EE. (The plate on my CK did come off without removing the gearbox).




    Took the opportunity to clean up and paint the shelf on the lathe that the gearbox sits on. Note the critical box of ziploc bags on top of the headstock.




    Made a quick press plate with a hole tapped for 1/2 - 13 to use in place of the bearing cap to press the shaft out. Yes, that's a galvanized carriage bolt I'm using there, it was what I had on hand.






    I got the shaft shifted over enough to free up the taper roller bearings on either end. I'm pressing the whole center bearing, outer race included, out in the process. It bound up a little once the bearings on the end were free. I took a lunch break at that point I need to take a careful look at those taper orientations .....
    Last edited by rabler; 05-01-2021 at 09:01 PM.

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    The middle bearing is hanging uo on one of the gears on another shaft. So going to have to at least partially pull that other shaft, or maybe shift this shaft in the opposite direction ...

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    Started to pull out the other shafts, then had an inspiration after I'd already shifted one of the other shafts a tenth of an inch or so. One the shaft with the tumbler, the left side of the shaft is a larger diameter than through the tumbler. So the tumbler has to come off the right side of the shaft. Which lead me to try to initially drive the shaft left. When doing so the center roller bearing hung up. But if I drove the shaft initially right, it would unseat that bearing race. And then I could remove the circlip next to the bearing, and then drive the shaft left. That worked, and the tumbler is out.




    With the two tumblers side by side, the only difference appears to be that the back of the tumbler has a machined radius whereas the replacement tumbler is a rough casting. Given how this seats on the mechanism that shifts the tumbler left/right, I may have to mill this smooth. The replacement tumbler also has bushing set in the casting, where the original was just bored to diameter, but same inner diameter.


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    They usually don’t machines surfaces that don’t need it, I’d agree you might want to match the broken part.

    And ouch! That’s an ugly break AND repair.

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    Quote Originally Posted by Homebrewblob View Post

    And ouch! That’s an ugly break AND repair.
    I’m pretty sure it was done with the gearbox on the lathe, just opened the front faceplate.

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    Quote Originally Posted by rabler View Post
    I’m pretty sure it was done with the gearbox on the lathe, just opened the front faceplate.
    You giving excuses? Hmmm, suspicious.

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    Good to see you are well on your way to having this fixed. Hope it all goes back together well and works as it should .

    Mike

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    Quote Originally Posted by mikethomas View Post
    Good to see you are well on your way to having this fixed. Hope it all goes back together well and works as it should .

    Mike
    Got the tumbler in. Fits and looks like everything meshes appropriately. Working on getting the QCGB back together and back on the lathe.
    Mike, thanks for the part, quick delivery, and just being overall easy to work with on that part, much appreciated!

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    Just thought of this, but while its off might want to replace a couple of seals it you havn't already decided to do so. I picked them up myself off ebay, maybe $15 bucks total.

    And if you have the plate on bottom side of yours, maybe pull one bolt at a time and silicone it in, or re-gasket it.

    A thread re-popped up recently explaining it:
    Monarch Ser.60 Gearbox Removal Illustrated

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    Quote Originally Posted by texasgunsmith View Post
    Just thought of this, but while its off might want to replace a couple of seals it you havn't already decided to do so. I picked them up myself off ebay, maybe $15 bucks total.

    And if you have the plate on bottom side of yours, maybe pull one bolt at a time and silicone it in, or re-gasket it.

    A thread re-popped up recently explaining it:
    Monarch Ser.60 Gearbox Removal Illustrated
    I'll take a look at seals on the back of the gearbox. Your right it would be a good idea to replace those before re-hanging the gearbox.

    I have a bunch of 1/32 cork/buna gasket material from McMaster, which I've used in some places where a good gasket is needed. Mostly on the 10EE. The 612 has a few differences. If you look at the picture above with the 612 lathe after the QCGB is removed, you'll see a large hole under the gearbox in the very front left corner. I think the 61 has a oil pump there? That hole fits a screen and drain hose that goes back into the hydraulic/lube reservoir under the headstock. This recovers oil from the oil lines to the end gears, but is also set up so that any oil coming out under the gearbox will drain there. There is a feed line coming off the headstock that goes into the oil distribution system. So it seems leaks from the QCGB are almost expected? or at least of no consequence??

    I wouldn't want the bottom to leak too drastically, as there is a phenolic gear under the tumbler that picks up oil to lube the tumbler, (same as the 61?), which needs a bit of oil in the bottom of the gearbox as a reservoir. I resealed the bottom plate with Permatex form-a-gasket, which has worked well for me before, in that unlike RTV it doesn't turn into an impossible to remove adhesive. I'll probably use the permatex for the rest of the gaskets.

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    This needs a little cleanup before going back on, but this is the lip that bolts onto the QCGB at the headstock end of the lathe. Comparing pictures to the above model 60 thread, looks like they'd done quite a bit of work to try to make these things less likely to drip oil. You can see the channel in the top of the lip that collects oil from anything running down the cover above, and if you look closely there a couple of small drain holes in the channel. The clutch shaft coming out of the back of mine is above oil level, so I'm not going to mess with the seals. The rapid traverse bevel gear is internal to the shaft plate on the apron side of the QCGB, and doesn't effect the rest of the gearbox.



    Also, didn't have to do anything other than take the top plate off the gearbox to remove it, since the shifter assembly is gone on the 612. Getting to the left top capscrew that held the QCGB onto the lathe was tight, had to cut about a 3/4" chunk off a 1/2" hex wrench, and use a wrench on that.

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