Member postings for ChrisH

Andrew - I am seriously impressed by the accuracy you are obtaining on you ‘old’ lathe, and green with envy!

Jason - forget what I wrote about the dti check, in the middle of the night it suddenly made no sense to me. What I had measured with the dti was the out of true along the top of the bar, or the radius, not the diameter as the mic showed. Sometimes your brain makes things fit what you want to believe as opposed to what is actually being shown, that obviously happened to me yesterday. Today I went and remeasured with vernier calipers and got a conformation of the readings the mic had shown; I can’t explain the dti reading at the moment but I am sure someone more clever than I will be able to, but perhaps it is as you suggest, the spindle axis is out of true of the saddle axis, either up/down or side-to-side. Perhaps I will check with the dti along the horizontal plane, see what that shows?

If the spindle axis is out of true with the saddle axis, what on earth do you do about that?

Chris

Neil, “ That suggests to me the saddle IS twisting a little” I would tend to agree with you, EXCEPT, that I have the gib strips so tight I can’t see how it could twist!

Hansrudolf, the lathe is Weiler LZ280. I think the age I gave must be wrong as I think it is a 1960’s lathe, certainly pre1970, which would make it 45 years old, or perhaps even more, my apologies.

The dial gauge I mounted on a magnetic base which was fixed to the carriage. I zero’d the gauge at the outer end of the cut length, then advanced the carriage towards the chuck. The reading went down, or up depending which way you look at it, by 1.6thou of an in.

The Weiler is a very good quality lathe, very well built, but it has also been well used in the past. I got it from a boatyard firm that went bust about 8-10 years ago. I make the “well used” observation from the state it was in when I got it!

I think I could possibly get a better accuracy, I would certainly like to think so, but the questions are could I, given its general wear? and how? and at what cost in time and effort? and at the end of the day is it worth it? What do others get? Yours is commendable certainly!

Chris

While having my evening soak in the bath, pondering the day’s play while supping a pint (how the retired live!) I got to pick up on a couple of things that John McNamara had said which made me wonder a few things.

Am I expecting to get too fine a degree of accuracy from a well used 35+ year old lathe? With the inevitable wear that such a machine has, am I actually going to achieve much better?

Is 1.6thou over 90 mm really unacceptable? That’s only ½thou over 1 1/4 inches, how often am I going to need greater accuracy in that in real life?

A lean over 1.6thou from, or to, the vertical over 90mm, what angle does that make, could you measure it (yes I know you could calculate it, but on the milling table)? Would you notice it?.

Am I wasting time and effort in trying to achieve a result which would be wonderful when what I have already got would be acceptable in 99% of the time, or more?

How accurate are other peoples lathes? (now I know, having asked that, someone will say they always get to turn ½ a thou over 10 inches or something!!). I would love to know what other people are working to.

What are the thoughts on the above?

Chris

A PS to my post just now, today have been only taking cuts one way, towards the chuck of course, and when I wind the carriage out, by hand with the lathe stopped, the tool is not leaving a mark on the turned bar, so that must be a plus point too!

Chris

Edited By ChrisH on 10/04/2013 18:50:37

Well, having had a fair bit of time in the workshop today, on the lathe, I am not that far further forward.

I ground a new knife tool in 1/2in sq. HSS and diamond honed it. I tightened all the gib strips, for the carriage, the cross slide and for the top slide. I probably tightened them a tad too much, as the levers were hard to turn after that. I then put in a 4thou cut and got 0.065mm difference between outer and inner ends of the test bar.

So I slackened all 8 holding down bolts, (4 round the headstock, 4 round the tailstock), took out the shims I had put in yesterday, tightened up the bolts hard hand tight, and took another 4thou cut. Out of true down to 0.04mm, or about 1.6thou, over the 90 mm.

And that was basically as good as it got. Tightened down with a hammer as it says in the manual, first at the headstock, took a cut, then again at the tailstock, took a cut, unhammered the hammered bolts and added the a 3thou shim, tightened up hard hand tight again, took a cut, each time the result was the same, out of true 0.04mm.

Only bright point was at the end I put a dial gauge on that reads to 0.0001in, and ran it down the length of cut and it confirmed that my mic readings were good!

Now ‘wasted’ two days and still turning 1.6thou out over 90mm. I know it is not acceptable but am tempted to leave it at that!  My next move will be, I think, to really go back to square one, take all shims out from under any bolts that they may be lurking under and start the ‘levelling’ process from scratch again, and maybe in the process thus rectify the twist.  But that won’t happen now until next week, as because we have been married for a significant amount of time, Senior Management has decreed that we go and spend a significant amount of money in a hotel for the weekend to celebrate. I did venture the opinion that it was seriously curtailing vital workshop setting up work, but for some reason that opinion was not well received…………… At least the place does a decent pint of cask, I understand, so perhaps all will be well in the world after all, and I can have a think away from the job!

In the meantime, I am greatly indebted for all the comments added, it has and is giving me serious food for thought - many thanks.

Chris

Edited By ChrisH on 10/04/2013 18:39:45

Wow, what an amazing response, thanks a lot! I will try and answer the points raised above:

I will check/nip up all the gibstrips to ensure minimum play can exist on the carriage etc. as a first step. Will also lock the topslide and cross slide when making a cut.

I agree that one cut one way should suffice, was concerned when I got the results indicated in the original post. Hopefully when it is set up right the lathe will not do that.

I was thinking that the tool overhang was too much, now confirmed. I intend to grind a new tool from a new piece of 1/2in HSS tool steel which should deal with any tool fexibility problems.

I did write down what I was doing and the results obtained, I have a note pad in the workshop which I use to write down stuff as I go along as I find it all too easy to forget what I have done - old age races on!

The spindle bearings are two back to back taper roller bearings and all is solid there, play wise.

I am not using a tailstock centre to support the work, just following Harold Hall's instruction in his book on the lathe. That is why I was also taking fine cuts, but I appreciate the point of perhaps the tool not cutting at times, will check on that. The steel is EN1A (or 230M07, whichever you prefer)

I think I will take out the shims that I inserted yesterday, slacken all holding down bolts off then just tighten them hand tight and start again, and report back.

Sorry about the mix of units by the way, I am of an age when we used feet, inches, thous, pounds, ounces, lb/sq.in, deg.F. I am now also used to working in meters, mm, kilogrammes, grams, and deg.C, (but cannot get used to metric pressure units, I use them if I have to but they just don't mean the same to me as psi!), my lathe although German has dials graduated in thous, tool steel is imperial but my mic's are metric as is my rule, such is modern life!

Chris

Edited By ChrisH on 10/04/2013 11:18:24

Neil, any ideas on how to do that?

Chris

Am I well wee'd off with this? Logged in, wrote a long thread, went to post it and guess what, a clever note saying I had to be logged in to use this facility. I WAS logged in or else I couldn't have written the thread. Why hasn't this been sorted by now? Moderators/web chiefs, please note. It is seriously annoying as well as a complete waste of the threadwriters time.

Rant over, now:

Anyway, what I was asking was HELP! Could someone please point me in the right direction and advise where I am going wrong.

I am trying to set up my lathe to turn parallel as well as then making one of Harold Hall's cylinder squares, but am getting nowhere fast.

My lathe is a German made Weiler lathe, about 35-40 years old. OK, it is a bit worn but quite OK within the area in which I work, very manageable. The lathe sits on a very robust welded mild steel bench made by Weiler, and is held down by four holding down bolts, one at each corner, of the headstock, and by another four at each corner of the tailstock. When I first set the lathe on the bench I set out to minimise the twist as far as possible with 6thou shims under the holding down bolts, as that was all I had at the time, being guided by a reasonably accurate level.

Today I set out to make it turn parallel and make a cylinder square in the process. I set a length of 30mm diameter bar with about 30mm in the chuck and a tad over 90mm as turned length. As originally set up, I got an out of parallel of 0.05mm, being larger at the outer end. In this case the manual says to harden down the headstock front right bolt, followed by the tailstock rear left bolt if necessary. As all bolts were already hardened down I thought again. Using another 6mm shim which was already cut to fit, I inserted it under the rear right headstock bolts and tried again with another cut. This time I got out of parallel of 0.04mm, but this time the other way round, the chuck end was bigger.

Simples I thought, substiture the 6thou shim for a 3thou shim and she'd be right. Wrong! Now it was out 0.02mm.

The lathe speed is about 300rpm, a very slow feed is being used, the tool is HSS ground on an off-hand grinder and honed with a diamond hone, it's 1/4in square and protudes from the tool post about 15mm, the tool is like a knife tool with a bit of approach rake (forget the correct term!).

I played with bit of different shim all afternoon getting nowhere, then I noticed an oddity which baffled me. My practice was to take a 2thou cut down to the chuck, and without touching anything bar reverse the feed, cut back out again. I noticed that on the cut towards the tailstock the tool was taking a progressively heavier cut, heavier being a relative term given the original depth of cut.

So I took another cut towards the chuck and stopped the lathe when the tool reached the chuck, and micrometered the bar. It was 0.09mm larger at the tailstock end. So I just reversed the feed and cut back out again, and remeasured after that cut. Still out, but now down to 0.035mm.

All this has, as I say, me baffled, the little grey cells are getting ever older! My thought process have seem to have been driven down a dead-end and have just given up tonight.

So can anyone, please please, tell me what I am doing wrong, why/how is the lathe cutting like that, and what I need to do to get back on track - I need pointing in the right direction!

Chris

PS, this damned website only wanted me logged in AGAIN, even though I was. Had copied what I had wrote this time but....

Edited By ChrisH on 09/04/2013 21:50:07

Maybe a hex head will not take as much torque as an allen socket head, maybe it can, I don't know the aswer to that.

The question to answer is did the h-t bolt take the manufacturer's recommended torque when it was tightened up? If it was torqued up to the spec OK then it doesn't matter, to my mind anyway, what head it has on it.

Chris

Edited By ChrisH on 06/03/2013 21:50:31

There was a so-called 'web.app' previously advertised on this site but it seems this was not much of a true 'app' judging by comments made about a year ago I have just found out on another thread.  So presumably the new app David talks about might be a proper app, but I with others await details on what it will do!

Chris

Edited By ChrisH on 24/01/2013 21:31:49

Edited By ChrisH on 24/01/2013 21:32:54

What benefit does having an iPad app bring?

Can you view the magazine any better than the archive issues allow you to? Find it hard to get much sense looking at an archived copy using the iPad, hence the query!

Chris

I have a welding machine which used to overheat and cut out when doing any serious prolonged welding. I also fitted a computer fan - the first one that came available, no research or calcs done there - and it transformed the welder, you can weld all day with no problems now.

My Gremlins are called the Little People. They keep borrowing stuff that is left on the bench, sometimes they return it after a few days exactly where I left it, sometimes they have put it away where it is usually stored. I think they are building something but I don't know what. And yes, I have this Black Hole too, where little bits disappear, again it's the Little People getting stuff for whatever they are making.

I thought my workshop was the only with with a Black Hole and the Little People, now it seems all workshops have them..................

ChrisH

Edited By ChrisH on 04/01/2013 11:36:30

Hi Kevin,

The Axminster Compact Bandsaw weighs just 29kg, which makes it very easy to get out from under the workbench and put it away again afterwards. It is compact too, just 800L x 280W x 800H are max figures, but still cuts up to 100 x 150mm rectangular and 100mm dia. Worth a look.

ChrisH

Beware of rearranging stainless steel with a hammer to get the flats - stainless gets brittle when hit and can then fracture.

ChrisH

Hi - I haven't used a chop saw but seen one used in anger a lot of times. They do the business OK, but are very noisy - anti-socially so - and messy in use with the dust that comes off. If you have one it needs to be used outside the workshop, but that makes the noise worse for the neighbours! As I said earlier, I think the Axminster compact bandsaw to be a very good machine.

Chrish

Am I the only one who was very much disappointed in this publication?

The history of the first engines and boiler was OK, then it seemed to tail off into a list of places you could see an engine. What about all the engines that were not horizontal mill engines, locomotive, power station and ships engines to name but three. Were was the charting of the development from the basic initial engines to the more advanced triple expansion engines, etc etc?

A list of places to visit is all very well, but in another book, I would have preferred more about just the engines and boilers that drove them, which is what I thought I was buying.

I don't down cry the effort that went into producing the book, I just wish that they had stuck to the title and not digressed into a tourist book.

Chris

Post above added twice by mistake!

ChrisH

Edited By ChrisH on 28/11/2012 22:37:06

The PDF documents for Sally - without the link that DavidinHK provided above, how would one find them on this site? I seem to be missing something here, because without the link I can't find them. Where does one look?

ChrisH

Hi SverreE,

I recommended these lamps from Ikea back in March in the thread 'Workshop Lighting'.

I have the one with a base for my mill, and the clip-on one for my lathe. I think they are excellent value for money and provided a very good degree illumination right where you want it, with the bulb bit being so small it doesn't get in the way. I would still recommend them!

Chris