Stewart, Many years ago I used to rebuild and sell on old lathes, 1960's, now I am not just sure how the head bearings on these machines are adjusted ora if they are tapered or a straight journal? However one thing I learned was that with straight journals you can have the too tight! I.e. No room for the oil and this causes chatter, I found that by allowing a little clearance for the oil, we are talking a minimal amount here the machine would cut just fine, tighten up and it nearly jumped of the bench with chatter.

Try it and see how you get on, hope this helps. John

Hi Stewart,

I've just gone through exactly the same experience with my own M type; no matter what I did the chatter would occur on anything but the finest of fine cuts.

Adjusting the bearings wasn't as simple as the manual suggests. I found that when I pulled up the big bronze nuts to the point where the spindle wouldn't revolve and tightened down the adjusting screw / oiler I'd got just one shot at it, the process isn't reversible so I couldn't fiddle about looking for perfection. It's because when you ease the screw back, the little lozenge piece it bears on doesn't recoil, it just stays put. So lesson one is to get it right first time and then leave it alone.

Even when I'd done that the chatter was still all too apparent. I eventually worked out by (tedious) elimination that it was caused by a sort of concealed end float. The spindle in mine was scored; not badly but enough to be concerned about.  On the shaft near the oiler holes I suspect cast iron or something had found a way in down the oiler hole and done the damage. When I adjusted the end float with the ground collar that bears on the exterior of the headstock spindle nut, I found two conditions; chatter or overheating. Loosely finger tightened gave chatter, a bit tighter gave rapid heating and squeally noises.

My conjecture was that the scoring was enough to resist movement from a finger tight collar, but not enough to stay put under the pressure of the cutting tool. There isn't any much lubrication between the collar and the bronze bearing so when they are brought together under pressure there's a lot of friction. My solution was to place a small needle roller thrust bearing between the two, (ie the bronze bearing nut and the ground collar).

Result …… chatter gone never to return. If you think this dodge might help let me know, and I can steer you to the bearing supplier. The one I got is an imperial size and a dead fit, no fiddling about required at all, and cost buttons from a UK source.

After I fitted it the note / noise from the spindle rotation was quite different from what it was before which was a bit off putting but it works well enough; I'm turning silver steel at 1050 rpm with a positive rake carbide insert nae bother.

Eug

Edited By Eugene Molloy on 22/09/2014 16:47:25

Edited By Eugene Molloy on 22/09/2014 16:49:02

Edited By Eugene Molloy on 22/09/2014 16:51:57

No. Drummond M's are one of the best hobby units you can get, good enough to run all day on mini production runs

The headstock bearings are definitely a pain to set, but it's well worth the effort

This is 36mm rebar I did on my M series, loads of intermittent cuts and a nice finish

Edited By Ady1 on 22/09/2014 21:07:31

Ady1

Thats very impressive, can I ask a beginners question; what is "blue carbide" and what speed and feed do you use?

My carbide inserts would be in a zillion shards trying that. I'll be turning some interrupted cuts on cast iron before long; would you recommend blue carbide?

Eug

what is "blue carbide" and what speed and feed do you use?

They seem to be standard carbide tools, but they definitely aren't as brittle as the red painted carbide tools which chip if you look at them harshly

I just experiment, break some, and figure it out as I go along.

I'm using one very successfully in my newly acquired shaper at the moment, carbide tools are fabulous because they go for so long between sharpening

Speed isn't fast, about 3-400 rpm and I listen to the cut as far as feed is concerned, no violence, it should be a soft hissing type noise. The relief angles are very shallow to maximise tool tip support and done by eye

The key to successful carbide work on a hobby lathe for me seems to be stiffness, everything I do is geared towards maximising stiffness and I have made a pretty massive toolpost to help

edit: which reminds me. You don't need to use the top slide unless you are doing tapers

I use a muckle toolpost on the cross slide

Edited By Ady1 on 23/09/2014 01:00:19

Stewart,

When I was playing chase the lady with the chatter the decision was to start at the cutting tool and work back down the drive train from there looking for problems; dead logical. Tool holder, tool post, topslide gibs, crosslide gibs, carriage lock, carriage fit, bedways, bearings, spindle, Uncle Tom Cobbleigh and all. The final thing to check, and thus the very last link in the chain was the end float adjustment, and guess what? That's what being logical does for you.

As Ady1 recommends I even ditched the topslide altogether and finagled a tool post to sit directly to the cross slide; it didn't help me with the problem in hand but it's not a bad move if you aren't turning tapers and such.

Eug