Member postings for Andrew Tinsley

Hello Keith,

You are absolutely correct in what you say. I would check out the back plate. However IF the previous owner had turned the back plate register down and enlarged the bolt holts to get the chuck aligned, then I am blowed if I am going to disturb the present set up!

What can be said without any doubt, is that the jaws are aligned to the lathe centreline within a thou or two (Which is good enough for me, as the chuck isn't my best one!). However the chuck outer body is NOT concentric to the centreline, having a run out of 25 thou. The best explanation is that of Keith Rodgers and that the jaws have been ground true. The outside jaws look as though they have never been used (still wrapped in anti rust brown paper!). If anything they are a touch more accurate than the normal jaws, the run out on various chucked pieces of rod is just over a thou.

I suppose I should just forget the pronounced wobble and get on with the turning. The trouble is that any of my friends that see the lathe at work say "I should fix that dreadful run out!". I am almost tempted to try and turn down the offending chuck body!!

Andrew.

Hello Jon,

The first thing I checked was that the jaws were in the correct order, I did say that in the post.

Jason. I would normally turn up the back plate to fit the register of the chuck. This I assume is what the previous owner had done. If the chuck runs true then fine, what bothers me is that the chuck register is not concentric with the outer chuck body. I see where you are coming from. But the point I am making is that I have never seen this mismatch with outer chuck body and its register.

I don't know how chucks are made, but I can hardly believe 25 thou run out on the outer body. Maybe the register is concentric with the outer and then the previous owner would have had to enlarge the bolt holes and turn down the back plate register to allow movement of the chuck, to get it running with the jaws concentric. Hence my comment about the possible difficulties that the previous owner might have had.

Andrew.

The Toolmex chuck that came with my Myford, is visibly off centre when running. The outside of the chuck wobbles!

Checking with a DTI, the outside of the chuck had a run out of around 25 thou! I casually checked the run out of a 1" steel rod at the chuck jaws and the run out was 2 thou! An 11mm silver steel rod had 1 thou run out! This was a totally unexpected result and I am glad I checked, as I was about to unbolt the back plate and remedy the 25 thou run out of the chuck body!

I have never seen anything like this before. The back .plate thread and the mandrel nose were clean and the jaws are in the correct order. How the previous owner managed to get the chuck running so well is a mystery to me.

Any thoughts on this intriguing situation?

Andrew.

Talk of the Red Arrows reminds me of an incident that happened at a display at RAF North Luffenham, a good many years ago.

I was in my single handed dinghy on Rutland Water, sun shining and hardly a breeze to be had, so I let go everything and watched the display over the airfield, drinking a can of beer. The display ended (for me) with the famous Red Arrows bombburst. One plane came streaking towards me at what I thought was a much lower height than was prudent. He went straight over the top of my boat and then pulled up,

The result was the boat suddenly capsizing! At least I had the presence of mind to hang onto the beer although somewhat diluted in the process!

Andrew.

An interesting little capstan lathe is on Ebay at the moment. It is described as an Edwards lathe, but has what looks like Acorntools cast into the stand. I am pretty sure that the stand goes with the lathe.

Lathes UK mention an Acorn tools capstan lathe, but this one is much smaller than the lathe mentioned in the Lathes UK write up. Edwards lathes are mentioned but nothing to do with this little lathe. Anyone ever seen one before?

It looks as though this is going to require a fair bit of work and parts may well be missing, so I shall pass on it!

Andrew.

Many years ago I saw the machining facilities at the place where uranium of the fissile variety (U235) was machined to make warhead components. If you think DU is bad then you should have seen this!

Andrew.

Hello Duncan,

Your material was either a matrix including tungsten or a tungsten alloy, usually with copper. They both machine with consummate ease. Pure tungsten can be machined with tungsten carbide or with greater difficulty HSS. In my experience you need plenty of coolant.

As for drilling or tapping it with normal kit, forget it, you will find that it will usually shatter, or break the tooling. Maybe a tungsten carbide drill might work, but I don't know if tungsten carbide taps are available!

Andrew.

So Acrylic and Perspex are one and the same! Interesting, you live and learn!

Thanks,

Andrew.

Sorry! I double posted,

Andrew.

Edited By Andrew Tinsley on 12/08/2017 15:52:30

As far as I am aware Acrylic is not Perspex. There must be a difference as the Acrylic is much cheaper than Perspex! Unless it is a case of "Branding" puts up the price!

Obviously I want to use Acrylic sheet as it is much cheaper!

Regards,

Andrew.

Yes , Pure tungsten is a bit of a swine to machine,. My friends big Tesla coil uses tungsten rods as electrodes in the rotary spark gap. Fine to face the electrodes up with a TC tip, but forget anything else. The Tungsten /Copper alloy is a much better bet for machining, but unfortunately the copper evaporates from the alloy in a rotary spark gap (60 amps at 11,000V AC)! It makes a right mess!

Andrew.

Thanks guys, so it does seem possible to do the job, but very difficult in execution! I was going to try a hot air gun and place the sheet over a cylindrical former. It is obvious that some experimenting needs to be done, but well worth a try.

Thanks again,

Andrew.

Is it possible to bend acrylic sheet (3mm thickness) around a tubular former with the application of heat? Also could one then "weld" the sheet to form a tube?

The weld is important, glue would not be acceptable in this application. I know that you can buy acrylic tubing, but not in the required diameters,12.5 " to 13".

The application is to prevent strikes on the secondary winding of a large Tesla coil. The strikes will go through glued joints with ease.

Perspex tubing of the required diameter can be had but at around £700 it is a route that I don't want to go!

Andrew.

I have one of the Warco Rumanian grinders from 20 years back (plus). It is an excellent grinder, very smooth and takes forever to stop. Mickey Mouse rests and eye shields.

Andrew

I had a strange experience, It was suggested that I googled Interparcels to get a quote for picking up and delivering a heavy parcel.

Cheapest was just under £12 using ParcelForce Express 48. Later I went to book this on the ParcelForce website. Imagine my surprise when I was quoted near £44 for exactly the same service!

I went and booked it on the Interparcel website. The only difference is that Parcelforce quoted insured maximum value at £100 and Interparcel was only £25. Strange, but still, I increased the insured value to £100 and it cost me an extra £3. So I got the Parcelforce Express 48 delivery for £15 rather than about £44. Some difference! So who is ripping off who?

Andrew.

I lost the Woodruff key for my electric motor. In desperation I just bolted up the pulley wheel very tightly and ran the machine sans Woodruff key. It stayed that way for weeks until I sourced the correct Woodruff key. On disassembling, there wasn't any sign of the pulley wheel having spun on the shaft!

So I reckon your solution would do fine. Before people berate me for being idiotic. I was desperate to get a job done and it was worth sucking and seeing.

Andrew.

As a light aside. Gold is very much better than copper when it comes to conductivity. During the Manhatton atomic bomb programme, the need arose for a lot of isotope separators. The amount of copper needed, impinged upon the supply of copper for the American war effort, so impasse. Until someone realised there was a lot of gold in Fort Knox, doing nothing! Yes you guessed it, Fort Knox supplied the material for the isotope separators electromagnets!

Andrew

Is this a 3 phase motor powered by a VFD or a simple single phase motor? It makes a big difference to the diagnostics!

Andrew.

I had the same problem with a 2metre length of 16mm threaded rod. I needed to turn down both ends. I simply put the length into the chuck by pushing it through the mandrel and thence into the chuck. My pal did the turning and I simply put a metre length of cheap 30mm plumbing plastic tube over the free end.

I thought this might be a bit dangerous, but in fact it was a total non event. The tube held the threaded rod and I held onto the tube. Easy!

Andrew.

I recently got a Royal shaper, having got rid of a very large machine a year or two ago. I have a very soft spot for shapers and they are really quite cheap, compared with other machine tools. OK not as versatile as a vertical mill but surprisingly they do things that most people never think of as possible.

My machine was in pretty fair shape except for play in the cross slide screw and nut plus similar in the tool downfeed. I am sorting these out and generally cleaning up the machine and look forward to some hypnotic shaping.

Andrew.