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Cross Slide Dial Too Loose

CalgaryPT

CalgaryPT

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I've got a CT089. It's been OK for my purposes, but I am using it more now than I used to. One annoying thing about this model has been that the cross slide dial has always been too loose. Is there a trick to tightening it? I haven't taken it apart yet, but it looks like even if I made a keyed washer/shim, this wouldn't solve the problem as only the center of the dial is torqued by the handle nut. The outside of the dial (knurled part) is actually the radius that spins. I had another lathe years ago with a way to tighten this, but don't see any obvious way on the CT089. The owner's manual doesn't show enough detail to tell if there is a way to adjust the tightness of this internally. I've also heard it is just wear and to order a new part.

This must be a common issue. Any ideas?

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Not sure what I'm looking at here, but does that knurled collar lock the dial to the cross feed screw assy via friction? Perhaps all that you need is a shim on the front or back of the dial?
 
Nope. The knurled part of the knob spins the notches on the dial so you can zero the cross slide. The handle (removed) engages the shaft key and tightens the handle again the center part of the knob (darker portion). This holds the handle on, but a washer/shim won't tighten the knurled outside portion as it is free spinning on the knob itself.

Maybe this pic will help:

lathe3.jpg
 
Replace or adjust the following???


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It's listed under lathe bed parts.

Just a WAG here.
 
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I think you are right. I'll take it apart in the next few days and inspect it. Thanks.
 
There's also an unnumbered part in the manual between 30 and 31. Can't tell from the diagram as it is low resolution. I wonder if this is packing (like used on plumbing parts). I read once this was once used on indicator dials and wears out. Ooooooooh...a mystery. I love those. Can't wait to take apart now :)
 
You are saying the graduated collar is loose & slips too easily as opposed to staying put like when you re-zero the dial?
Its been a while since I had my 14x40 apart but I recall there is a ball & compression spring. If yours is similar could be spring has lost some springyness, ball is wearing on the dial part ID... those sorts of issues. I've had the opposite problems where it rotates smoothly & then gets sticky. Usually its gunk buildup that need cleaning & oil. You might also have an axial thing where the tightness of the nut can affect free play <cough> design issue. Let us know what you discover.
 

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A quick "farmer fix" that I can see is to drill & tap the handle where it co-insides with the outer ring, install a grub screw with a "friction pad" between the screw end and the ring. A properly adjusted friction setting would allow zeroing but still have enough engagement to have the ring "follow" the handle when it is turned.

The benefit is that it can be adjusted easily from the outside forever, no disassembly required.
 
This isn't the article I was looking for but I seem to recall some Asian machines either have a rubber/plastic friction pad or were modified to accept one.
https://www.practicalmachinist.com/vb/general/cheap-easy-fast-friction-dial-lathe-339207/

Or if its a ball, I think I've hard rubber balls or certain kinds of plastic that might give the right feel in combination with the spring?

My mill dials have a knurled collar nut adjacent to the handle. I really like that system over the traverse set screw. Just loosen the collar nut, slide dial ring to position & tighten. There are no parts to wear or get out of tune really. My RF-45 has thumbscrews going in traversely which basically set against the shaft. It worked fine too. The dial body was thick enough it didn't distort. But after a while you get a whole bunch of little bite marks. A better design would be a slight recess groove for the thumbscrew to seat on so there are no raised burs to hang up dissassembly.
 
PeterT said:
This isn't the article I was looking for but I seem to recall some Asian machines either have a rubber/plastic friction pad or were modified to accept one.
https://www.practicalmachinist.com/vb/general/cheap-easy-fast-friction-dial-lathe-339207/

Or if its a ball, I think I've hard rubber balls or certain kinds of plastic that might give the right feel in combination with the spring?

My mill dials have a knurled collar nut adjacent to the handle. I really like that system over the traverse set screw. Just loosen the collar nut, slide dial ring to position & tighten. There are no parts to wear or get out of tune really. My RF-45 has thumbscrews going in traversely which basically set against the shaft. It worked fine too. The dial body was thick enough it didn't distort. But after a while you get a whole bunch of little bite marks. A better design would be a slight recess groove for the thumbscrew to seat on so there are no raised burs to hang up dissassembly.
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All good ideas Peter and @historicalarms. I know these indicators are not intended for exact measurements, and some would say who cares if they drift? But I find great value in them as a starting point before I pull out the calibers.

I have some acetal parts that need turning, then I will get to the dial and report my findings. I also have on my project list a big cleanup and partial tear down of this machine soon. I've have it for about 20 yrs. I think, so it is long overdue.
 
I find even with DRO that settable dials are super useful. My brain still thinks in terms of depth of cut, so its easier to dial in progressive increment like .025", 0.050... for most of the operation rather than mental math of subtracting some DOC equivalent off a DRO digital readout. I like DRO for knowing absolute position, repeatibility & mitigating backlash, but the dial grads are still useful.
 
PeterT said:
I find even with DRO that settable dials are super useful. My brain still thinks in terms of depth of cut, so its easier to dial in progressive increment like .025", 0.050... for most of the operation rather than mental math of subtracting some DOC equivalent off a DRO digital readout. I like DRO for knowing absolute position, repeatibility & mitigating backlash, but the dial grads are still useful.
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Don't most DRO's read in depth of cut? Maybe I am not quite understanding you... my "Igaging DRO's" read in depth of cut?
 
DPittman said:
Don't most DRO's read in depth of cut? Maybe I am not quite understanding you... my "Igaging DRO's" read in depth of cut?
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I had the same experience with CNC stuff, and the best way I can explain it is to compare an analog watch to a digital one. A digital one (think DRO) is precise (and presumably accurate) to the scale it uses. But an analog dial (think the graduations on the metal knob) shows the end points and the rate at which it is moving. Like an analog watch face the brain says, "at the rate I am driving I will arrive there on time" (or I need to slow down/speed up).

I think it is PlasmaCam software (but maybe not) that allows you the option to view the DROs as digital dials. This is very useful because you can see the rate at which you are cutting, together with its precision. I find the same with calibers and micrometers; although I have both I prefer analog because I don't have to subtract anything in my head...I can just visualize it based on the needle position.

I read once that Dr. Michael Burry, the hedge fund manager The Big Short movie was based on, could "see" numbers as analog representations of themselves. No way can I do that with a DRO. My brain won't allow that.
 
Depends on the DRO. Some of the liner style measure DOC just like your dials. My DRO can accept absolute diameter, so when I in-feed it shows the resulting reduced diameter. So thats what I mean the settable dials can still be beneficial. Example: if I mic my stock at some point of turning at its measures 1.234", I enter 1.234" on the DRO. Now if I want to take a series of roughing passes, I can just look at my (zeroed) dial & go .025 .050 .075... as opposed to looking at the DRO and going 1.184, 1.134, 1.084... I don't think anyone does it this way, its better to just pick a nominal even diameter on the DRO even if the first number is a bit higher or lower, so like 1.200 1.175 1.150... (this would be 0.0125" DOC equivalent, but hopefully you get what I mean)

If I want 3 passes of 25 thou & 2 passes of 10 thou DOC, the dial progression would be .025, .050, .075, .085, .095. If you are good at mental subtractions on the fly, you can forget the dials altogether & just watch the DRO. Its a preference, no right or wrong way. DRO's can still vary a bit & measurement influenced by finish & other variables so I typically turn to 10-15 thou oversize, measure actual diameter one more time, reset the DRO to that measurement & obey the DRO only for finishing cut.
 
I'll bet if I did this for a living I could get used to thinking more digitally. I think you're right when you say it is a preference. I just like the dial appearance. But one drawback is when you're turning or machining graduations over an inch and just watching dials you have to track that measurement as well. I've been known to forget. So I think having both is ideal, like those Mitutoyo Micrometers with both digital and analog readouts. I think a lot of people do as you do and trust the DRO as they do a finishing pass.

I had an older micrometer once with the little wrench that allowed you to zero it. I don't own a newer digital and analog one, but I think you can only zero the digital readout. That would annoy me.
 
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