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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: New motor for wabeco lathe
14/07/2022 07:22:20

Almost certainly a wound field DC motor, commonly used for larger sizes rather than permanent magnet field. Many controllers have an output to drive the field winding. A series wound motor is very unlikely in a lathe because it's speed torque curve is very unfavourable.

13/07/2022 17:59:37

Does it have brushes? If so it's a dv commutator motor. Several companies supply industrial drives suitable, Google KBE. But the motor might be a bit elderly and the brushes needing replacing anyway in which case a 3 phase motor and VFD upgrade would be a good approach.

Thread: Topslide question
09/07/2022 16:28:49

Yes! Can you file a wider slot? Or drill the head of the screw off. The "washer" is a ratchet cam for the previous toolpost.

Thread: chuck problems ? maybe others
06/07/2022 18:20:06

Have you had the jaws out?

Thread: Levelling an ml7
06/07/2022 18:18:26

PLEEAASSE, NOT AGAIN!

Thread: Can this small motor be reversed?
04/07/2022 22:25:50

https://www.model-engineer.co.uk/forums/postings.asp?th=133409

**LINK**

Thread: Making parting off tools
04/07/2022 19:28:10
Posted by Andrew Johnston on 04/07/2022 19:05:26:
Posted by Rowan Sylvester-Bradley on 04/07/2022 17:25:42:

.... I'm also in the part off using power crossfeed group.

Andrew

Absolutely!

04/07/2022 18:20:24

Parting on an old lathe with a home-made tool could be a recipe for frustration. Parting off is a rite-of-passage for lathe owners. I never had any luck with HSS parting tools. You can buy excellent carbide-tipped parting tools such as these:

https://www.rdgtools.co.uk/acatalog/8MM-Shank-Parting-Tools.html

**LINK**

which use inserts. I have a similar one actually made by Sandvik which I have used for years and it is excellent - in fact I just parted off a bit of 1" square steel using it running at 200-odd rpm.

In my experience parting off goes better with quite a high spindle speed and a fine X feed - I was feeding at 3mm/minute for my bit of square bar. This makes sure that the "tooth load" is small but there is plenty of heat being generated at the tool tip to soften the metal. The temptation for beginners is to use back gear and try to feed very slowly by hand - inevitably the tool digs in, the lathe stalls and the air turns blue.

Thread: Avoiding jitter when turning brass
04/07/2022 18:08:07

CZ121 is nice to machine. But...that looks like an AWFULLY wide tool! If you're really turning with what looks like a 1/4" wide edge it's not surprising you get chatter. If you are aiming to reduce the diameter of the hex down to 15mm you need a knife tool which you feed in the X direction (i.e. parallel to the lathe axis).

04/07/2022 07:40:18

Chatter? What grade is the brass?

Thread: Adding a microswitch to Carl Wilson's Arduino Controlled Indexer - MEW249 refers
02/07/2022 13:24:54

easybutton.h is your friend...

Thread: Parkside Electronics
01/07/2022 12:41:59

How on earth was a DIN plug wires in a way that allowed that to happen? Not the student's fault!

Thread: Adding a microswitch to Carl Wilson's Arduino Controlled Indexer - MEW249 refers
01/07/2022 11:33:32

If you have a stepper power feed on the x axis as well, then GRBL can move the x axis back and forth and drive the divider too, controlled with a few lines of gcode from UGS.

Thread: For all you Myford owners
29/06/2022 11:11:29
Posted by Bob Unitt 1 on 29/06/2022 10:45:51:
Posted by Neil Wyatt on 28/06/2022 18:42:15:The Myford VMB (mill) and Mystro MK2 (a wood lathe) were made in Taiwan.

Neil

I bought a VMB direct from Myford in the 90's, having visited the factory. I was told by the guy selling it that what came from Taiwan was used pretty much as just a set of castings. They were completely stripped down, all the supplied electrics thrown away, casting-sand cleaned out, mating surfaces corrected as required, some bearings replaced, and then rebuilt with all-new electrics. They may also have replaced the motor, but I can't swear to that as it was some time ago. Certainly mine hasn't given me any trouble since I bought it.

So it was Myford that held in one of the column mounting bolts with paint on mine then?

Thread: "Recycled" Plastic - Abrasive?
29/06/2022 09:23:10

So not injection moulded then!

29/06/2022 07:20:13

I could imagine that they don't do much pre-processing of the waste plastic before making the new material, so it could have all sorts of crud included.

Thread: Single phase milling machine recommendations
29/06/2022 06:56:38
Posted by Macolm on 28/06/2022 22:03:17:

.......

I perhaps did not make it clear enough what the (mild) concern is. At resonance, the inductive and capacitive reactances are equal in magnitude but opposite in phase, so they cancel and thus there would be no phase shift of the start winding current. Thus if it were possible for resonance to happen, the motor would likely not start or would run slowly, but would draw excessive current in the start winding as well as stall current in the run winding, a recipe for rapid destruction.

 

I just wondered whether there is any reason to caution about experimenting with a wide range of capacitor values.

In the situation you describe, though there would be no phase shift of the current in the start winding, there would be in the RUN winding since if the motor is stopped it will look inductive. The start winding current though would be limited only by the winding resistance so it had better start quickly!  This thread might be interesting:

https://www.model-engineer.co.uk/forums/postings.asp?th=133409

https://www.model-engineer.co.uk/forums/postings.asp?th=133409

Edited By John Haine on 29/06/2022 07:18:41

Thread: For all you Myford owners
28/06/2022 12:05:31

I did buy a big-bore S7 in the early 2000s but I wouldn't buy one again. Yes, it's OK, precise and all that, but the design is very poor for a 21st century machine. Bed design not very good, there's a reason why most lathes have prismatic beds. Plain tapered headstock main bearing? Flimsy topslide. I'm sure that the complex drive system made sense when induction motors with decent power were expensive but all that countershaft stuff is a real nuisance now not to mention I suspect very expensive to make. The Myford 7 is really a fashion item. They could have got high-spec versions of the bigger Sieg lathes made and upgraded them in the UK, painted them in Myford colours and given a suitable new name, fitted 3 phase motors and VFD, and probably still made a bigger profit.

Thread: Single phase milling machine recommendations
28/06/2022 08:15:31

Why YT? This https://topcharger.co.uk/can-i-get-three-phase-power-at-home/ May be just as useful.

**LINK**

Suggests 4000 to 7000 sqids. A decent vfd looks a bargain. Why bother with horrible capacitor bodges?

Thread: I am going to buy a mill….Decisions, Decisions !!
26/06/2022 10:28:29
Posted by Ian Parkin on 26/06/2022 10:01:39:

.....

if the product arrives and works as makers intended then its ok …so 3 months should be adequate to find any problems

.....

Well, after owning a MYFORD VMB for 3 years or so I discovered, when I got round to tramming the column, that one of the hold down bolts was held in the casting by paint.

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