Here is a list of all the postings Douglas Johnston has made in our forums. Click on a thread name to jump to the thread.
|Thread: How to machine Acetal|
The sharp polished carbide tips as sold for aluminium are what I use and they work a treat giving a very nice finish. They don't seem fussy about speed or feed rates. In fact I now use these inserts for most of my cutting from plastic to aluminium to mild steel and stainless steel, they are just superb tips especially on smaller lightweight lathes.
|Thread: Buying a Reel of Bandsaw Blade|
Silver soldered blades work every bit as well as welded ones, I have been doing it for years and have never had a joint fail. Just a decent scarf joint as mentioned above does the trick. I overlap the scarf joint and place a very small piece of silver solder between the ends and flux the joint. With everything in a simple jig to keep things in line I use two of the tiny butane torches ( the kind poncy chefs use in the kitchen ) above and below the joint and wait a few seconds until the solder fills the joint.
Edited By Douglas Johnston on 27/05/2019 19:59:22
|Thread: heat reflecting foil|
What a good idea Clive, I was wondering how to place the foil behind the my radiators. There is very little room behind the radiators which makes the task somewhat difficult, but your idea sounds like an easy solution-must give it a try.
|Thread: stamford show vandals|
The sad thing is that others who might want to exhibit their work will be put off doing so in light of this. I was a secondary teacher for 30 years and know full well that the vast majority of kids would never do this, but it just takes a few mindless idiots to inflict such misery. My heart goes out to the owners of the destroyed exhibits, it must be devastating to see ones work treated in such a barbaric way.
As has been said the perpetrators will probably get no more than a slap on the wrist and given a few hours community service.
|Thread: EMCO Compact 5|
Great little lathes and very well made, I used one for years. Value is very difficult to say since condition is the main thing, but one in very good condition could fetch £500 I would think.
Right Clive, I pulled the dial off and took a few pictures. I used three spring loaded ball bearings as you can see, the balls run in a groove on the inside of the moveable dial. This technique gives a very smooth operation of the moveable part but may be overkill. Fitting the springs and the balls without losing some of the bits provides a great exercise in manual dexterity. If assembly is done inside a plastic bag flying ball bearings will be caught.
I did this to my Speed 10 many moons ago and it was well worth doing. It was so long ago I have forgotten exactly how I did it but from what I remember I used the original engraved dial, bored out the middle to form a ring and made a straight knurled outer part for adjusting the scale. If you want more information I can dismantle it and take some pictures.
|Thread: fly cutter or face mill|
Looks like a blunt cutter to me or poor chip clearance. Poor tramming of the mill can also give this result where a trailing edge messes up the finish.
|Thread: Lubrication of Quorn grinder spindle|
I built my Quorn many years ago and think the book does mention something about lubrication if my memory serves me correctly. I think it needs a small amount of oil and to be honest I think I just put a little oil on the bearings during assembly and have never added any since over the last twenty years or so (perhaps I should ).
I too have seen the use of Sodium Bisulphate on the web and have also bought some of it to experiment with but have not got round to trying it yet, so your efforts have encouraged me. I was wondering what strength of solution to use and see you opted for a 25% solution. Was that percentage based on anything other than a stab in the dark?
I have heard that the solution does not keep well which may be a disadvantage. The chemical is not that cheap so could be quite expensive if it is a case of use it once then have to throw it out. It might however be the only way to anodise if Sulphuric Acid is impossible to source.
|Thread: Parting tool|
I have just got my latest purchase from China via ebay and am rather pleased with it. It is a 2mm wide parting tool complete with 10 double ended inserts and a very nice torx screwdriver all for less than a tenner. I feared I was wasting my money but the thing has greatly impressed me. The quality is perfectly satisfactory, while not brilliant, and the inserts seem to cut very nicely indeed, slicing through steel very cleanly.
The tool has a 12mm square shank which I had to reduce to 8mm to fit my Speed 10 lathe. I was worried that the shank would be very hard but a carbide milling cutter cut it very easily with a few passes at 50 thou depth of cut and left a very nice finish. Well worth a punt at that price.
|Thread: ML7 feed screw wear|
Just had a look at the Myford/RDG prices and have to say the word "cheap" did not come to mind, but perhaps that says more about me than anything else. Over £400 for a topslide , good grief you could buy a whole Chinese lathe for that.
|Thread: Where's my Dykem blue gone - there's no need to read this|
The trouble really starts when you forget what it was you were looking for.
|Thread: Poor finish using indexable lathe tools on steel|
+1 for the sharp polished inserts sold for aluminium. As said they work a treat on steel. Was doing some 50mm diameter mild steel this morning and the finish was superb, but you need to be careful since the edges can be damaged quite easily if mistreated. And yes keep the speed up.
|Thread: Notre Dame|
Very sad to see such an iconic building in such distress.As has been said there have been a string of high profile fires during renovation and I can't understand why there are not people on site around the clock to reduce the risk to the buildings.
|Thread: stepper driver|
This may well be a theoretical problem with the 6560 drivers but I have been using a number of these for quite a few years and have never had one fail. Even if one did fail they are so cheap it would hardly be the end of the world. Also they seem to withstand back emf's when manually turning the stepper motor ( can be very handy with double ended motors when you also want manual control )
|Thread: Boring on a light mill|
When using a boring head in the mill is it better to provide the downward feed with the head locked and using the quill or the quill locked and using the head feed. I have used both methods in the past with success but have often wondered which way is best from an accuracy point of view.
|Thread: Mini boring tool|
Seems to be only available to companies when I looked. I suppose I could try to invent a company to fill in their form but I'm sure they would show me the door.
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