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Member postings for John Haine

Here is a list of all the postings John Haine has made in our forums. Click on a thread name to jump to the thread.

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Thread: MT3 to 3C collet adapter article
28/02/2010 10:38:54
Just to clarify please - is this article in the latest issue the first of a series?  It isn't clear if there is to be a follow-on, it is very interesting and relevant to me as I'm taking my first steps in CNC turning having converted my Super-7, but it leaves off at a crucial moment!  Always end with a cliff-hanger eh?
 
John.
Thread: marking blue
19/02/2010 20:22:49
I keep a box of cotton buds in the workshop - soak the tip of one in blue and paint it on - if it's a large area then put a little puddle on the work and spread with a bud.
 
Mind you, I just bought some permanent marker pens!
Thread: How to prepare Hot Rolled Steel for marking/machining
18/02/2010 21:02:56
It's black.  And rough.  You just have to mill off the scale.
 
Thread: Blown X1 Mill speed control
16/02/2010 21:23:35
Some time ago I bought a very nice DC servo motor which is destined to be fitted to my X1 when it gets CNC'd.  It came with a speed controller from KB Electronics in the USA - http://www.kbelectronics.com/ - it's the KBWM type.  I haven't tried it yet but I did see it operating at one of the shows.  These controllers use thyristors and are quite clever having speed compensation and have a good rep I think.  They have some UK stockists, not sure how much it would cost, could be a good replacement for one of these pesky X-series speed controls which judging from the X series forum are always blowing up.
Thread: Knurling
03/02/2010 12:07:38
If the circumferential pitch of a knurl is of the order of say 1 mm, the perimeter of the work will be an integral number of knurl cycles long as long as the diameter is an integral multiple of  "1/pi" mm, or about 0.3 mm.  If the depth you form is at least this much then surely the metal will deform to match the "integral number of teeth" criterion whatever the diameter of the work. (Adjust these parameters to suit the actual knurl pitch you're using.)
 
This seems to correspond to what many people are reporting.
 
I have also read in MEW of a type of knurl which has a sharp face on the side and, mounted rigidly in the toolpost, is fed in from the end so that it actually cuts rather than forms the pattern - can't remember the name offhand.  I suspect that with this type the diameter and in-feed will be critical.
Thread: Boring tools for Boring Head
25/01/2010 20:45:41
I think George Thomas' book has full instructions IIRC.
 
Thread: Prescription Safety Specs
24/01/2010 16:43:16
I got some single vision close-up prescription (like reading but not so close) from Boots with side guards - transparent panels that conform to the lens outline and protect the eye from bits entering from the side.  Don't use them now though cos eyes have changed!  I think this is a very standard pattern, used to see people in the model shop at work using them.
 
 What would be nice is a pair of upside-down bifocals so I can see the dials on the lathe easily through the bottom but things closer than  that through the top...I keep having to tip my head back painfully far to get very close things at near eye level in focus.
Thread: Solid Alcohol
24/01/2010 09:16:23
a/k/a metaldehyde
 
also used as slug death
Thread: Boring tools for Boring Head
23/01/2010 09:45:43
I usually use the brazed carbide ones from one of the sets that Chronos etc sell - never had a problem, set the angle by eye usually.  If you look at a commercial boring bar with an insert they usually have negative top rake, as you have found.  I also have a smaller (and nicer) Arrand boring head with which I use a tool which has an 8mm shank with a 3/32 HSS rod at an angle at the end (held by grub screw) on which you grind your own cutting edges - this works fine too and is good for small jobs.  You could easily make  an equivalent.
 
John.
Thread: Tachometer design
19/01/2010 20:39:58
Might be worth noting that the Mach 3 CNC software incorporates a tacho which is needed for screwcutting - it needs to know how fast the h/s is rotating to get the right feed rate; and also where the spindle is to start the cut in the right place.  This means the timing requirement is pretty tight.  It only needs one pulse per rev, so obviously takes the reciprocal of this time to get the speed.  So I'd think this approach is maybe the way to go, and it only needs a single slot sensor disc or a reflective mark on the spindle.  I made a simple sensor using an opto interrupter out of an old printer and an ali disc with one slot on the back of the spindle and it works a charm.  No need for any schmitt trigger or anything, just a 4k7 pull-up on the phototransistor collector.
 
Interestingly, it showed that the speeds on my Super 7 were all slightly faster in reality than shown on the plate on the lathe - 233 rpm instead of 210 for example.  Not significant for straight turning but sure b*******d the thread pitch until I realised what was happening!
 
John.
Thread: Brass Shell Case
13/01/2010 16:36:40
I think I recall reading somewhere that cartridge brass (which this may well be!) doesn't machine at all well - in clockmaking I think they recommend some different alloy for plates that you can easily drill.  IIRC, may be best to go for a manual sawing operation, it sounds like trying this in the lathe could result in a messy dig in.
Thread: Microscope objective thread
07/01/2010 21:31:01
Thanks again to all, and especially to Meyrick for his very practical suggestion which I just carried out.  Mind you it wasn't easy, but it looks like the thread is about 0.6 mm pitch.  Given that its diameter is just under 15mm and .6 mm is 42.222 TPI, looks like this is an example of that last microscope "standard" I referred to in my initial post.  The fit of the lens in the turret is disgustingly sloppy anyway, so I don't think it's too critical, as Ian says.  Turning the thread will be a good test for my lathe CNC conversion.
 
John.
 

Thread: Workshop Heating
07/01/2010 18:09:34
Richard's problem was I think not because it was a catalytic heater as such but either because (a) it was venting into the w/s (in which case it generates just as much water and CO2 as a flame); or because the air was allowed to get warm and moist before the machinery; (or both).  When the air gets warmer it can hold more moisture, and if this is available from somewhere then it can condense on the cold machinery because the air in contact with it cools down and hence its relative humidity increases above saturation.  (If you warm the air without adding more moisture then its rel humidity decreases and condensation is less likely.)

The ideal approach, if you are not going to keep the shop warm all the time, may be to have a space heater for the air (such as an externally vented gas heater or fan heater or whatever) for when you're working, and something to keep the machine tools warm when you're not.  This could be for example by having them covered with a plastic sheet when not in use and putting one of those small low wattage electric heaters with the tool under the sack so all the cast iron keeps warm.  As long as the metalwork is hotter than the air it shouldn't form condensation.
Thread: Microscope objective thread
06/01/2010 09:10:09
Thanks Alan, a clever suggestion!  I have tried counting the threads against a rule under a x10 glass, unfortunately the screwed section is very short, only 6 or so threads, so one can't get a good average.
 
Happy new year to you also.
John.
 
04/01/2010 21:33:18
Thanks for the responses.
 
 As well as Clarkson cutters, microscope threads are characterised by metric diameter and TPI pitch - as in the link Chris provides.  E.g. Japanese JIS and German DIN standards are 20.1 mm x 36 TPI.
 
I guess if I had a thread gauge I wouldn't be asking...(if it had this pitch on it...)
 
Thread is certainly 55 degrees.
 
Chris, thanks I'd seen that website which got me to where I was when I posed the question....I think either I'll take a punt on 15mm x 36 TPI, or just use some araldite!
 
Of course, once I've set up the microscope I could easily measure the pitch......there's a hole in my bucket too.
Thread: Workshop Heating
03/01/2010 10:31:58
For example from caravan shops.
Thread: Microscope objective thread
02/01/2010 13:46:12
I winder if anyone can help with a query on an unknown thread please?
 
I have a cheap microscope (from Aldi!) with a video eyepiece option which connects to a PC.  I want to cannibalise it to mount the optics on a different base with a small XY table for measurement purposes using the "Centrecam" software.  The microscope objectives have a fine thread which is 14.86mm OD, with a pitch I estimate to be about equivalent to 35 tpi.  Sorry for the mix of units but apparently it's common with microscopes to use inch threads with metric diameters!  There is a standard thread called "RMS" for Royal Microscopical Society which is 36 tpi and made in different diameters so I wouldn't be surprised if this thread is also 36 tpi.  Also apparently some lenses are made with 15mm diameter but these are usually 42 tpi!
 
So my question - has anyone else come up against a microscope lens thread of about this size and could they confirm the exact dimensions?
 
TIA, John.
Thread: Water Tank Adhesive
01/01/2010 20:33:34
I think the handles falling off problem may be more to do with the fact that dishwashers are hot.  Lots of wooden boats are made using the West system with epoxy fillets sealing wooden bulkheads against salt water and subject to heavy impulsive loads, which don't fail even after many years.  Using epoxy to seal joints which actually depend on bolts for joint strength against clean cold-ish water sounds much more benign.  You could try as an alternative to Araldite West System epoxy with glass microballoons to thicken it as sold by Axminster for example.
Thread: Pillartool
01/01/2010 20:23:51
When I do cotters I make both halves separate (for a split cotter) and clamp then in their bore with a thin washer in between, then bore the main hole for the thing they're clamping.  Then you don't have to part the cotters, just remove the washer.  For a single cotter put the washer at the bottom of the hole.
Thread: Comments on the Exhibition
01/01/2010 10:58:13
On the contrary, surely?  My father-in-law taught packaging design and was a master of "paper engineering"....making effective complex structures from cardboard is a very specialised technique fully deserving of being described as engineering. 
<< First < Prev 271 272 273 274 275 276 277 278 279 Next > Last >>
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