Member postings for Eugene

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

duplication

Edited By Eugene Molloy on 22/09/2014 23:12:34

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

Stewart,

The supplier is "Simply Bearings", the part number is NTA1220 + TRA1220 @ £6.41 ex VAT, and it only takes thirty seconds to fit. I have another M type, a long bed ,wanting some TLC and I'm going to do the mod willy nilly.

If you are going to go through the fag of getting the spindle (and the cursed backgear) out, slip the thrust bearing in immediately you get the spindle back in and before you do any adjusting. End float needs to be done after the bronze bearings have been taken care of.

Best of luck,

Eug

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

After I built my small shed / workshop and kitted it out, The Management, a great gardener, declared it was so nice that she wanted one as well.

No sooner the word than the deed and she now has her own gardening shed with all her tools and clobber neatly racked and stashed. She's quite happy to sit on the step with a coffee and admire all her hortimecultural stuff. So she gets my vote as a proper Shed Lady.

John is dead right about the home workers shed. My mat Pat, headmaster of the local school has one for all his admin and planning tasks plus industrial scale home brewing. We've plucked geese in there too but the ambiance and appearance weren't much improved by cubic yards of goose feathers. You can drink redcurrant wine with furry down in it but it's not the pleasure it aught to be.

Eug

Edited By Eugene Molloy on 19/09/2014 11:51:33

Rik,

Solubility is indeed temperature related, normally the hotter the solution the higher the solubility. So at 20 C you can get a saturated solution of material X but at 40 C you can get more to dissolve. So boiling doesn't really come in to it.

Eug

Depending on the temperature 75 grams of citric acid will only make a saturated solution of around 100 ml of water. I'd just cover the part and tip in all the citric you've got . Suck it and see, then if you think a higher concentration is needed, get some more acid.

Eug

Sorry, posted at much the same time as Bob

Eug

If I was making a casting pattern from a finished object that vernier could be quite handy, adding as it does about 8% to the actual dimension.

Eug

Llanidloes, myself.; anyone else around this area?

I've been lurking for some time in the forum; just a beginner home machinist rather than model maker. Currently setting up a wee workshop between Newtown and Welshpool.

An email to [email protected] will find me.

Eug