Thread: Chucks & Camlocks

Hi Bryan,
This has been discussed on many forums, but I have never heard of a pop, as long as they come around to the mark you are right. In the Grizzly lathe manuals it shows you how to adjust them and what the marks look like.
As for the gap there should be about a thou which should get pulled up when you tighten the cam locks.
When undoing it should take a bump with a rubber hammer to get it off the taper.
Here is a thread that comes to mind from recently.
Camlock D1-4 Adapter plate

Dave

Hi Bryan,
I see no mention of pops in your link.
The only thing I know of that could be called a "pop" is the sound the detent pin makes when the camloc is turned to the open position.

"causes these to be drawn inwards until the pin goes over-centre and locks"
As I understand it that's just wrong. If you turn the camlock far enough to go "over-centre" you are now on the way to being undone. That's what the little arrows ">< on the spindle are for, the mark on the camlock should be between those marks.

Having said that I notice the camlock pin holes are below the camloc holes in your link. My spindle is the other way around, though I can see how that would change much.

Stuart

Thanks Dave, some great reading there.

Stuart, to me 'over centre' suggests something that resists movement up to a point, then springs forward. That's what I meant by a pop. If over centre doesn't mean that I don't know what it means. But clearly this doesn't happen in practice. And it wouldn't be the first example of erroneous or poorly written/edited material on that site.

I have camlock chucks on my lathe and change them often. To avoid having another tool (the rubber hammer) floating around in the swarf tray I have fitted a piece of copper to the camlock chuck key as per the pictures. Just a slight tap with the copper end is enough to loosen the chuck.
Mm.

Originally Posted by Bryan

Stuart, to me 'over centre' suggests something that resists movement up to a point, then springs forward. That's what I meant by a pop. If over centre doesn't mean that I don't know what it means. But clearly this doesn't happen in practice. And it wouldn't be the first example of erroneous or poorly written/edited material on that site.

Yeah, can't see a way to make that wording fit what I think is actually going on and I've made some so I'd like to think I've got a good idea what's going on. Still I wouldn't like to explain what happens in three sentences or less lol

Sketchup works great BTW, I'm sure there is much more to learn but I can get a 3D piece done in no time. Thanks

Stuart

I agree with Stuart, that if you go to centre or over it, you have gone to far and need to turn the camlock stud in one more turn to stop this happening.
They hold by friction of the camlock, and there is no stops inside to stop them after going over centre, so they are free to rotate right around.

Who ever thought up the idea was really clever, as it is a great system with little if any error for repeated mountings.

Also it would be a good idea to pull the camlocks out and check them over for burrs etc, then give them a light oil and replace them. They come out after you undo the Allen head bolt and there will be a spring under it, and a round key with flats on either side of the end where it sits in the camlock groove. Very simple but effective.

The 4 jaw direct mount and face plate I picked up new/second hand both needed machining some off the back to make them sit right on the taper, as they where loose. In that thread I linked to above, I explain how I did it by mounting one chuck in another face to face so it could be turned around to try, you could do this with your back plate you want to make. If you buy one you may have to do it anyway.

When you get the chuck mounted properly don't forget to find it's truest running spot on the camlocks and mark both the chuck and the spindle. When you face a face plate do this before machining and that way it will always run true after mounting because it will be in the same spot as it was machined..The 4 jaw doesn't really need it, but I did mine anyway so if I have to pull the chuck off mid job for something, it will go back on the same way.

Dave

I was wondering if anyone as ever seen or knows if there is a torque chart for tightening the camlocks. One man's just snug is another's neck vein and shoulder popping tight. I would be happier with a torque wrench in hand. My lathe has a D1-5 spindle.

Pete

Hi Pete,
I've been on the lookout(although not that hard) for just that thing, as yet nothing. The problem maybe that because a cam is involved torque wont tell you much. For the same tension a higher torque would be required if the cam engages early in the rotation than as you get to the top limit of rotate.

Stuart

Dave, my 3 jaw falls off when you release the cams, so I'm giving that a tune up and will follow your advice. The 12" 4 jaw fits nicely, needing a bump to remove, but sadly it's cactus, damaged beyond repair I think. Will post some pics later. I have a used 10" on its way from ebay but will need to make a backplate. That should be fun.

They hold by friction of the camlock, and there is no stops inside to stop them after going over centre, so they are free to rotate right around.

Just as a point of interest, mine will only turn 180*

Metalman, that's a neat idea. Copper is not something I have much of lying about, but if I can find some suitable material I'll try that.

Stuart, the first time I made a 3d shape with Sketchup and rotated it on the screen I was hooked. I'm just a very basic user, but people do amazing things with it.

Stuart what you say is logical but I can't help but think that there should be something of a range. At some point I might just tighten the chuck up a few times without a torque wrench and then use it to see at what torque it loosens at with one. That should give me a ball park to work with. When I worked as an aircraft mechanic we always used a torque wrench to tighten important stuff because no matter how good the mechanic was you couldn't rely on feel to be consistent or accurate. I feel a big hunk of steel spinning at 1500 rpm qualifies as important. It is a credit to the design and the designers that it is so forgiving when it comes to tightening them.

Pete

I have never seen or heard of a torque wrench being used on a camlock chuck,maybe someone out there does.

When I fit a camlock chuck whether that be by hand or use of crane I position the chuck into the correct locateing hole and then nip each one inturn.

If the chuck is large usually after nipping 2 pins the lifting sling or jig can be removed and the chuck then rotated to the next pin for nipping.After all pins are nipped I then tighten them untill I cant turn the cam any further,I have never had a problem with any thing becomeing loose.

I have never seen a torque chart either, but on other forums I have heard people asking for it and evidently there just isn't one.
I lightly tighten each camlock so the two faces come pretty close to closed, then go around again and tightening them as tight as I can get them with a (300mm edited below) 240mm (120mm either side) T handle, which pulls the two faces together completely. Mine is a Chinese machine and I see no wear on them after nearly 7 years, only shiny patches where the camlock stud rubs..

Bryan,
I would be interested to see one of you camlock out, they might have the retaining slot mill only half way around. The ones on mine have a retaining groove all the way around with one detent hole, or maybe yours has two detent holes?.

Here is a picture of one of mine where I had to move the detent hole over slightly so the hole would line up in the unlocked position.

Dave

Originally Posted by Bryan

Just as a point of interest, mine will only turn 180*

Well now you have to pull one out so we can see what's going on . It wouldn't be any great trouble to make them that way, just mill a slot halfway around the pin rather that turning a slot/groove all the way around it.

Originally Posted by QC Inspector

Stuart what you say is logical but I can't help but think that there should be something of a range.

I hear what you are saying Pete but I don't see how it can be done by torque and even less how it could be done by torque then angle of rotation. Say you have a pin which is just loose enough to allow the camloc to turn. X torque on the camloc gives you Y tension. If you undo the pin one turn so the camloc can turn most of the way around, X torque will now give a greatly increased Y.
Thinking about it more I guess there could be a torque, the fact that it wouldn't reflect the tension on the pin doesn't really matter at all. As long as its somewhere between "tight enough not to come loose" and "tight enough to damage something" that's all that matters.
Maybe if the cam was an oval rather than just an offset circle it could be made to move a set distance for a given angle, within limits. Although, coming at it from the other side, assuming we aren't talking about people adding pieces of pipe or making long handled keys. How much torque can be applied? Maybe its a bit like the old Hurst(i think) shifter motto "shift as hard as you like, just don't break your arm"
I've only seen one story of a camloc chuck coming off a lathe and that was because 1
pin was missing and over time the other two broke. Still I wouldn't like to be an example for others in this case.

Stuart
p.s. omg 40 miutes to type that?
"as tight as I can get" I dont do them up anything like that tight(at least I dont think I do). Just a handle either side of the key shaft and nip and a bit. Don't have a torque wrench here so I cant come up with a number.

On my camlocks, I don't get a "pop" either when tightening, but when undoing them I sometimes get a "click"... I watch the gap as I tighten them up. not sure if that helps anyone.

Regards
Ray