Camlock spindle issue

bentwrench · Dec 19, 2022

I am working on my 10L with a D1-4 spindle and something is off. I bought the lathe and tore it apart to move into the basement shop, put it back together an cleaned it up. I have a few attachments for it, and a new back plate I need to machine to mount a 3 jaw. My experience with a camlock is that they press onto the taper when you cam them in, and when you remove them they need need a slight bump to knock them off. On my spindle you can push the back plate on the taper and hit hits the flat face of the spindle before you tighten the cams. I blued the taper and there is a good fit on register it with 2 attachments, but the new back plate doesn't seat as well, that one feels the loosest of the bunch.

I measured the front of the spindle and things don't add up. The taper protrudes .434"and it is supposed to be .4375 to the flat face. This would explain the loose feel to the attachments. Before I start facing my back plates or dress the spindle I figured I better ask for some advice and investigate further.

eKretz · Dec 19, 2022

So are you saying that *none* of your chucks tighten up on the taper before they hit the flat face of the spindle? Or only just the one? That is left a little ambiguous by your wording.

And yes, they should lock up on the taper with around a .001" or .002" gap on the flat, then be pulled up tight to the face by the cam locks. I would be checking carefully, as you don't want to make that fit too tight on the taper or the flat part won't seat, and you'll lose most of the rigidity the mount is capable of. That 7/16" dimension is not really important, it's a scale size. The original intent was to have .0005" to .001" interference fit on the tapered diameter.

bentwrench · Dec 19, 2022

None of them feel like they fit properly, 2 of the attachments feel like they are a perfect match, by that I mean no interference on the taper. These were used back plates from a face plate and 4 jaw. The new back plate I have to mount my 3 jaw is perhaps slightly loose (by that I mean by maybe few tenths, certainly less than half a thou) I this is odd to me that three different back plates would be "loose" and so I suspect the spindle my have been reground on the taper. The spindle nose is dead on, no axial runout and none on the face either.

I could just face the back of the D1 adapter plates and make them work, I also can borrow a tool post grinder and dress the spindle face for a "correct" fix. It is my understanding that some interference is needed for a proper fit and good reputability. I don't want to fit my 3 jaw to the new backplate until I have the issue sorted out.

The larger D1 machines I have been around need some pretty stout persuasion to get attachments off after the cams are opened, on this little guy I have to hold the chuck against the spindle because it falls right off when I open the cams.

How repeatable should a D1-4 be? I assume it should in the tenths.

eKretz · Dec 19, 2022

Yeah it sounds like you do have a fit issue. It's a tricky thing to measure a taper. Seeing as how you have a difference between the backing plates anyway, I might be inclined to do the work there rather than to the spindle. Got any photos of the spindle nose?

The camlocks I've worked with all had to be tapped off the spindle nose. One rap with a dead blow hammer was adequate in my experience. And yes, repeatability was always less than .001" when I ever bothered to check it.

johnoder · Dec 20, 2022

bentwrench said:
None of them feel like they fit properly, 2 of the attachments feel like they are a perfect match, by that I mean no interference on the taper. These were used back plates from a face plate and 4 jaw. The new back plate I have to mount my 3 jaw is perhaps slightly loose (by that I mean by maybe few tenths, certainly less than half a thou) I this is odd to me that three different back plates would be "loose" and so I suspect the spindle my have been reground on the taper. The spindle nose is dead on, no axial runout and none on the face either.

I could just face the back of the D1 adapter plates and make them work, I also can borrow a tool post grinder and dress the spindle face for a "correct" fix. It is my understanding that some interference is needed for a proper fit and good reputability. I don't want to fit my 3 jaw to the new backplate until I have the issue sorted out.

The larger D1 machines I have been around need some pretty stout persuasion to get attachments off after the cams are opened, on this little guy I have to hold the chuck against the spindle because it falls right off when I open the cams.

How repeatable should a D1-4 be? I assume it should in the tenths.

Helpful info. Dim to "sharp corner" - which no longer exists due to grinding relief - was 2.5005 plus .0005 on spindle. Chucks just say 2.500 +.0005 "to sharp corner". The standard B5.9 has numerous pages devoted to gage tooling drawings that were part of this standard. I have attached one related to D type

bentwrench · Dec 20, 2022

Thanks, John, that makes sense after taking some measurements. The big diameter on the cone is way under that 2.5005 spec ( I measured 2.483) and I was scratching my head because the fit up wasn't near that bad. Here is a picture of the nose, a few apprentice marks on the face but otherwise it looks normal.

eKretz · Dec 20, 2022

Looks like some pretty decent wear to me. Are there any grind marks visible on that face? I'm sure it would have been ground originally. It won't measure 2.5005" at the big end - as John noted, that's a theoretical measurement to the sharp corner where it meets the face.

animal12 · Dec 23, 2022

That was my thought maybe a burr ?
animal

eKretz · Dec 23, 2022

Yeah, taking a closer look, it does definitely look like there are a couple high lines on that larger face. It appears in the image to my eye that a stone has been taken to that face but the high spots weren't stoned all the way back down. Could be that rectifying that would solve much of the problem. It's worth a try.

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