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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.

Thread: Myford dividing head
22/11/2009 15:52:33
I just measured the distance between the screw holes on one of my plates - slightly tricky to do, I used a vernier caliper between the "insides" then the "outsides" of the holes and averaged; also they are not all that accurately drilled.  As far as I can see they are on an equilateral triangle with side 20.64 mm centred on the plate axis.  If my sums are right the PCD must then be 23.83 mm.  or 0.938 inches.  However I also tried scribing a one-inch circle on a piece of ali and laying the plate over it with the holes positioned as closely as possible over the circle and it looked like it fitted pretty well!  From experience I know that Myford seem to like whole inch measurements where they can so I wouldn't be surprised to find that 1" is right.  When I get a mo I'll try to measure it more accurately.
 
Sorry I can't be more definite!
 
John.
Thread: workshop and tooling requirements
22/11/2009 12:07:50
Having owned a couple of lesser lathes I bought a Myford S7 and have never regretted it.  If you can stretch to a reasonable used Myford, or something similar such as a Boxford, I would highly recommend it rather than one of the cheaper imports.
Thread: true Space
19/11/2009 18:18:30
Has anyone had any joy learning Turbocad?  I bought a discounted version at MEX a year ago - I count myself as a skilled user of most PC applications including many drawing packages over many years, but it has me TOTALLY BAFFLED!
 
Anyone know of a simple tutorial for it maybe?
 
John.
Thread: Books for beginers
16/11/2009 08:39:10
I found Guy Lautard's "Machinist's Bedside Reader" series very interesting and useful....though much more advanced than me at the time I bought then (and still!) I keep finding as I come up against problems that a solution is there in what I gleaned from these books.
Thread: O-ring coming off pulley when motor power is cut
12/11/2009 21:07:21
Ideally, fit the roller clutch in the bore of the driven pulley so the vertical driveshaft runs inside it, putting the clutch the right way round so that the pulley drives the shaft but if the pulley stops the shaft will continue to rotate freely.  Alternatively, put the clutch between the motor shaft and its pulley.  Obviously you will need to provide some bushing to stop the pulleys moving along parallel to their shaft.
Thread: Milling on a lathe
12/11/2009 21:01:37
Chris,
 
When I got my VMB I did as Myford recommended and got the R8 taper.  On my old mill I had a Pozilock (MT2), but I bought R8 collets for the VMB and have never missed the old Pozilock.  They are excellent, minimum overhang, tight cutter holding, accurate, and the collets are economical to buy as they are used widely in the Bridgeport (I think).  Never again will I use a separate collet chuck if I can avoid it.  On that experience I would recommend using collets direct in the lathe spindle taper for milling in the lathe if you can get them.
 
I have used both slot and and mills for counterboring - as long as the smaller hole is drilled first an end mill should work.  As someone above suggested, best to first drill the counterbore with a normal  drill and just use the cutter to "flat bottom" the hole.  This however is in the mill, probably a bit more rigid than the lathe vertical slide so go carefully.
 
John.
Thread: Woodwards gearless clock
11/11/2009 14:06:04
Mike, I haven't built one yet but I'm thinking about it so very interested in any experience you could share.  Have you tried simply increasing the weight?  It may be that there just isn't enough "oumph" (sorry for that technical term!) to keep the pendulum going.....
 
John.
Thread: O-ring coming off pulley when motor power is cut
11/11/2009 09:17:40

Edited By David Clark 1 on 11/11/2009 09:56:26

Thread: B & Q Steel stock
05/11/2009 09:53:02
I was really excited that they have a store in Cambridge, until I realised it was in Ontario!
Thread: TA8435H stepper driver
04/11/2009 18:52:25
Hmm.
 
That page links to this:
 
 
which describes the unit with the connections including the usual enable/direction/step inputs.  Also describes use of Mach 3 and the unit comes with a copy of Mach 3!  Obviously expect you to use the normal E-stop via a break-out board.
 
John.
Thread: "Precision" or "does NOT do what it says on the tin"
04/11/2009 16:19:42
I think one lesson here is to ask suppliers of all this low-cost tooling for a SPEC before buying.  First, you can then check that the spec meets your needs; and also whether the kit meets the spec.  The first might save you hassle buying something unsuitable; the second gives you easy comeback at the supplier.
 
Talking of PGMS by the way, I bought a length of 1" centreless ground PGMS from a supplier at a MEX a few years ago....it measured 1" diameter OK, but it wasn't round at all as I found when I tried to mount it running true in the 4Jaw! 
 
John.
Thread: TA8435H stepper driver
04/11/2009 09:18:50
Ken, these are just the driver ICs, looking at the data sheet.  You would normally connect the limit switch to the software that drives the drivers, for example to the Estop input if using Mach 3.  Info on the IC is available at:
 
 
John.
Thread: where can i buy a bell punch?
02/11/2009 21:23:40
Do you really need one?  Seems to me that to be accurate you have to face off the end anyway otherwise the cone will not centre properly anyway.  If you have to face it you may as well centre drill it!  There must be a reason why the things aren't made anymore, maybe this is it!  IMHO, a vee-block on a flat surface and a scribing block is just as good and much more versatile.
 
John.
Thread: Work positioning in the 4 jaw chuck
01/11/2009 11:23:58
For a job like this I'd face both ends; centre-punch where you want the hole axis; open the jaws of the 4-jaw too wide; clamp the billet with one end against the flat face of the jaws and the other with a centre in the tailstock with its point in the centre-pop mark so the pressure of the tailstock holds the billet.  The carefully run the jaws up to the billet and tighten them progressively being careful not to shift the billet.  Job done, quite accurate enough I'd think for a job like this, no need to use a DTI.
 
John.
Thread: Visiting UK
24/10/2009 11:03:00
If you are interested in clocks and instruments, two not to be missed are the old Royal Observatory at Greenwich (take in the rest of the National Maritime Museum as well) where they have Harrison's clocks;
 
http://www.nmm.ac.uk/
 
and the Whipple Museum in Cambridge
 
http://www.hps.cam.ac.uk/whipple/
 
(the latter possibly not worth a trip to Cambridge on its own but there's lots of other stuff there including the Corpus Clock
 
http://www.chronophage.co.uk/
 
Depending on the breadth of your engineering interests there is Bletchley Park
 
http://www.bletchleypark.org.uk/
 
 
How long are you in the UK....?
 
 
John
 
Thread: Depth of cut
23/10/2009 10:24:36
Eric, I have a Myford VMB with a fixed table, dovetail-slide head and movable quill.  The quill only has a "drill type" downfeed (for drilling!) so accurate vertical feed has to be applied via the feed screw.  It works fine.  Whether the same will work for other mills I don't know
Thread: Milling Machine Low Speed Torque
16/10/2009 20:27:34
Peter,
 
Going back to your original question about improved drive electronics, you could look at "Pentapower" units from KB Electronics (http://www.kbelectronics.com/).  I got one of these with a DC quarter-horse motor from Model Motors Direct (not used yet but may be fitted to my CNC mill conversion).  I gather this has compensation for motor speed reduction with load so could solve your problem.  The one I have is the KBWM240.
 
Cheers, John.
 
 
Thread: Clarke milling attachment
16/10/2009 20:14:54
Frankly, I would just get an X1 mill and not bother with trying to add an attachment to an older lathe.  The X1 with the long table from Arc Euro Trade is quite a nice machine and will take much bigger workpieces than a lathe saddle, and as you say the price is at least in the same ballpark.  I just bought an X1 for conversion to CNC because I didn't want to risk messing up my Myford VMB (and the latter is also a very heavy machine to work on), and I think that though it has a few limitations it's a nice bit of kit.
 
John.
Thread: Electric motors
16/10/2009 20:04:00
Mike, I used to have an Amolco imperial head that I paired up with a metric Amolco XY table.  I replaced the vertical feedscrew with a new one made from M12 stainless studding, with a new nut turned up from brass bar.  Also added ball thrust races to the bearing which made it a lot freer.  It worked well, though I never got round to re-doing the graduations which were still "imperial" based and didn't work so well with a 1.5 mm pitch screw.  Anyway, the maths was easier than using the imperial screw!
 
John.
Thread: Rear mounting parting-off tools
16/10/2009 19:54:54
Um, I don't get Clive's argument here.  Yes, if you are pushing the tool in and the cutting forces pull the tool into the work then any backlash in the feedscrew & nut means that there is nothing resisting the pull.  But equally if you are pulling the tool in and the cutting force is also pulling the tool in, then again any backlash also means that there is nothing to resist it.
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