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Upper Headstock End Cover "Latch"

jfl4066

Plastic
Joined
Apr 20, 2018
Hi all,

I have a '53 square dial lathe. The 1/4 turn "latch" that engages the spring loaded plate to retain the cover always gives me heart burn when re-installing the cover. :angry: Everything lines up and no gaps anywhere to indicate misalignment. At close inspection the plate does not slide easily on the screws and binds when the 1/4 turn dowel pin tries to ride up the bevel cut into the plate. There is no wear on the holes, plate, or screws. Has anyone modified this "latch" or made a new design?
 
I have a 42 round dial that I modified the plate on. I kept installing and tweaking the plate until I got a positive engagement that gave me assurance the cover wouldn’t fall off, while still being easy to install.

The “knobs” you have to turn are the plate thickness, depth of the circular cutout, and I used washers for spring force.

Don’t be afraid to modify or make a new plate, you don’t want that cover to fall off because they aren’t easy to find. I’ve attached pictures that will hopefully help


936a6869dcce327d00dd7a7a9e92dffe.jpg


36d9398aa4bce8681025c0acf962ed3f.jpg



Sent from my iPhone using Tapatalk Pro
 
Thx for the reply Crazymonkey,

Yup that's the bad boy LOL. Right now when the screws are tight, there are about 3 threads within the holes. When the pin pushes on the plate the plate sticks on the threads and only the upper part of the plate moves. The plate tips instead of moving along the screws. IMO Monarch built a high precision lathe but let the apprentices attach the embellishments and knobs. Every trim piece has threaded screws off in an angle. Any way, I'll make new screws with no threads exposed and tweak the plate bevel and notch. :)
 
Thx for the reply Crazymonkey,

Yup that's the bad boy LOL. Right now when the screws are tight, there are about 3 threads within the holes. When the pin pushes on the plate the plate sticks on the threads and only the upper part of the plate moves. The plate tips instead of moving along the screws. IMO Monarch built a high precision lathe but let the apprentices attach the embellishments and knobs. Every trim piece has threaded screws off in an angle. Any way, I'll make new screws with no threads exposed and tweak the plate bevel and notch. :)

I think you are 100% wrong about that lock. It is a very nice design and works very well. That is my opinion and I'm sticking to it, but it is based on owning about half a dozen 10EE's. Never had a problem with it. By works very well, I mean that it has a strong camming action, so when the knob is turned there is an initial resistance, then it pulls the cover against the headstock and locks in place and doesn't budge. Pretty good feat when you consider the weight of the upper and lower covers. However, it does depend on a few factors that you have not mentioned. The lower cover needs to be adjusted to fit correctly, because it supports the weight of the upper cover and establishes the height and alignment of the upper cover. I would start there. Does the lower cover fit snugly all around? Do all three pins wedge in place? The lower cover supports are often installed incorrectly by prior owners. They only fit one way, they were machined to fit when the lathe was built, so if they are in the wrong place or upside down, there will be problems.
 
I think you are 100% wrong about that lock. It is a very nice design and works very well. That is my opinion and I'm sticking to it, but it is based on owning about half a dozen 10EE's. Never had a problem with it. By works very well, I mean that it has a strong camming action, so when the knob is turned there is an initial resistance, then it pulls the cover against the headstock and locks in place and doesn't budge. Pretty good feat when you consider the weight of the upper and lower covers. However, it does depend on a few factors that you have not mentioned. The lower cover needs to be adjusted to fit correctly, because it supports the weight of the upper cover and establishes the height and alignment of the upper cover. I would start there. Does the lower cover fit snugly all around? Do all three pins wedge in place? The lower cover supports are often installed incorrectly by prior owners. They only fit one way, they were machined to fit when the lathe was built, so if they are in the wrong place or upside down, there will be problems.

I'm the 2nd owner of my lathe and have been for 30 years. Everything is original. My lower end cover sits and locates on 2 bottom pins and one top pin in the middle. Very well aligned. The upper end cover sits and locates on 2 bottom pins and has the 1/4 turn latch on top. It also is very well aligned. Seams are tight and straight. The latch rotates smoothly but it struggles engaging the taper part of the plate. Has been for 30 years.
 
I'm the 2nd owner of my lathe and have been for 30 years. Everything is original. My lower end cover sits and locates on 2 bottom pins and one top pin in the middle. Very well aligned. The upper end cover sits and locates on 2 bottom pins and has the 1/4 turn latch on top. It also is very well aligned. Seams are tight and straight. The latch rotates smoothly but it struggles engaging the taper part of the plate. Has been for 30 years.

OK, check a few things. I'm still guessing that it is an alignment issue. When the top cover is in place but the latch is not engaged, the top should be located by three points: the bottom supports and the body of the spindle lock. i.e. you should be able to push the top cover towards the back of the machine, with no rocking or movement, all three points make contact. It should be dead stable and should not move when the latch is engaged. Second, the swing on the knob should expose ½ of the pin in the disk that latches the cover (look at it from the side edge of the cover, as you turn the knob), and there should be no slop in the bore that the knob rotates in. Third, the plate that the pin engages has a notch on the left side, its height should be sufficient that the pin fits into the notch without contacting the plate or the headstock. Fourth, the angle of the notch should be 45 degrees where the pin contacts it. If it is worn into a circular arc, make a new plate... Now make a mark on the top of the knob that corresponds with the pin. The pin should contact the 45 degree bevel about 5 degrees before tdc. When it is locked and the pin is in the notch, the pin should be about 10 degrees after tdc. All measurements are estimates ;<)

If that doesn't solve the problem, please take some photos and post them.

-Dave
 
Hi Dave,
I'll post some pictures later today...

1. Top cover sits nice and square on the two bottom pins and around the spindle lock. It will sit there with latch not engaged. Since the bottom pins are in the respective holes I cannot slide the cover towards the back of the machine, so I don't follow what you mean.
2. The knob rotates nice and smooth in it's bore, no slop or wiggle. It also does not move up and down. The pin does protrude 1/2 of its length from the disk.
3.Plate has the notch. Can't see how it engages pin since cover hides it.
4. The angle in the plate is 45 degs. No wear. The plate is hardened.

Since the cover hides the pin engagement, I'm going by feel and peeking into it with cover slightly pulled back. The Plate does not move smoothly along the screws. The plate tilts towards the cover because the holes are getting hung up on the screw threads.
Does your plate do the same? I can only turn the knob to the 5 deg position. It does not go further. I'll try to get pictures of it.
 
Some More...
Knob Index.jpg
This photo shows the angle of the knob when the pin engages the angle cut of the plate. It will not turn further.

Lower left Loc Hole.jpg
Lower Left Locating Hole

Lower Left Loc Pin.jpg
Respective Locating Pin

Lower Right Loc Pin.jpg
Right Locating Pin
 
Here are a couple pictures that show the contact and latch positions of the knob on mine:

IMG_0505.jpgIMG_0506.jpg

It appears to me that mine is contacting the plate closer to tdc. Try adding some shims behind the plate.

-Dave
 
Hi Dave,

I finally found the problem. The pin on the 1/4 turn knob was hitting the headstock casting just before the plate. Not letting the pin go past the bevel. I ground off approx. 0.030" and it did the trick. The pin was just long enough to interfere and if you really forced the knob rotation it probably lifted the cover enough to get past.
Thx for your time Dave. Your input got me thinking.
Pin.jpg
 
Hi Dave,

I finally found the problem. The pin on the 1/4 turn knob was hitting the headstock casting just before the plate. Not letting the pin go past the bevel. I ground off approx. 0.030" and it did the trick. The pin was just long enough to interfere and if you really forced the knob rotation it probably lifted the cover enough to get past.
Thx for your time Dave. Your input got me thinking.
View attachment 290188
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Excellent Glad you got it working.

Dave
 
"PM at work, doing what PM does best." Just not always in any sort of RUSH?

Amazing that we JF put up with piddly s***t 30 year at a go, his case, nine years here, plus at least two of the prior owners, in my case..

...and all the while "if ony we had thought to ask" there's another brother as has had the knowledge all along!

But we DIDN'T think to ask!

Thanks, Dave!

Bill, glad I could help. The Monarch forum has always been a great place to get help, I have benefitted more times than I remember.
 
Any chance someone can take measurements of the latch parts? I'm pretty sure the pin is 1/4" diameter. What I don't know is the dimensions of the eccentric and where the holes are or the dimensions on the hole in the cover itself. I'm making up a cover from a new raw casting for my '41 round dial as the machine didn't have any covers when I got it. At the moment I have nothing to reference other than a few photos. Thanks in advance for any help.
 
Any chance someone can take measurements of the latch parts? I'm pretty sure the pin is 1/4" diameter. What I don't know is the dimensions of the eccentric and where the holes are or the dimensions on the hole in the cover itself. I'm making up a cover from a new raw casting for my '41 round dial as the machine didn't have any covers when I got it. At the moment I have nothing to reference other than a few photos. Thanks in advance for any help.

If my square dial cover has the same latch system as your round dial. I can give you some measurements.
 
Based on the photos posted, it all looks to be the same. I have the same plate/screws/springs that fasten onto the headstock. Your help is much appreciated. Regards, Fabio
 








 
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