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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: Convertor Issues 240V 1 phase to 415V Three Phase
19/10/2018 09:30:19

There is almost certainly a soft start mode available in the inverter that will limit the inrush current if you study the manual.

Thread: Stepper Motor Identification
19/10/2018 09:23:29

That's a NEMA 23 motor - 2.3 inches.

Looking at the Stepduino schematic and the driver IC datasheet the current is set by two sensing resistors on the board and a potentiometer which allows adjustment. It doesn't say anything about what that should be adjusted to, but from the component values and the driver datasheet the maximum current is about 2.5 amps. So if you could find VR3 on the PCB and adjust it to about half-way the current would be ~1.25A which would be about right.

19/10/2018 07:35:45

The first thing is to use a multimeter to check the windings. I would guess that it has two centre tapped windings, which can be used with unipolar or bipolar drives. You want to use the latter nowadays. For this you need to find the centre taps, and then not connect them but use the ends of the windings as a1, a2, b1 and b2 as in the stepduino guide.

The motor voltage is a red herring, what matters is the current. If you use a modern driver it will typically need around 24 volts upwards and will allow you to set the drive current to what your motor needs. The Stepduino has two such drivers installed. I assume it has a facility to set the maximum current. If you start at 1 amp you can't go wrong. If you don't get enough torque and the motor isn't getting too hot then turn it up. Forget the voltage, that will be taken care of by the driver.

Can you post a photo of the motor?

Thread: ML10
14/10/2018 08:17:11

Things are worth what people are prepared to pay. An alternative to watching eBay to find out is just to put the lathe direct on eBay yourself with lots of nice photos and a good writeup. Don't use buy it now, either you overprice it and it doesn't sell or feel you did sell but left money on the table. eBay has a huge reach and an auction system designed to maximise the price. If you use eBay just to see the price you might get, how else would you get anything like the audience?

Thread: A question for electronics wizards
14/10/2018 08:10:09

One bridge rectifier with the ac input connected to the speaker output of an amplifier, smoothing cap on the dc side, drive the leds through a suitable resistor. Robert is your father's brother.

Thread: Quick change toolpost
13/10/2018 16:55:00

I don't understand why you are so keen to spend more money on another TP system when the Dickson type works fine if properly adjusted and clamped.toolpost1.jpg

This is mine, bolted down firmly to a machined base on the crosslide. You can't see it but there's a 6mm dowel through the hole in the top surface into the base casting to stop the block rotating if the clamping isn't enough. I've never had a problem with the clamping of the actual tool holders on to the block but it is a well proven design and as Jason says probably a simple adjustment. You may be surprised just how hard tools and their holders need to be clamped to avoid movement under cutting forces.

13/10/2018 14:04:51

The Dickson type that you have should have a hole through it to fit a dowel into the topslide to stop it rotating. I have a similar one on my Myford and needed such a dowel to prevent slight movements which play havoc when you are trying to reference multiple tools.

In fact your photo shows the hole at the bottom right of the holder in its normal operating position.

 

Edited By John Haine on 13/10/2018 14:06:10

Thread: 1-2K Which Mill?
13/10/2018 09:30:20

I hadn't picked up on the SX3.5. Looking at the picture of the X powerfeed, it looks very much like it may use a stepper motor - is this the case?

Thread: Twin Tube HF fluorescent lighting for the workshop
12/10/2018 18:29:51

Adam, is the earth connected to any of the lights? If it isn't the only way there can be an imbalance between L and N is via an earth fault in your wiring. If the lights do have an earth then sometimes a filtering capacitor can create enough of an imbalance to trip an rcd. So if there isn't an earth check your wiring carefully as it might be dangerous.

11/10/2018 22:14:57

Have replaced 3 fluorescents with LED "tubes" and use LED work lights almost exclusively in the workshop. No problem with strobe effects.

Thread: Stepper power for autofeed on lathe
09/10/2018 22:22:17

The Z feed for my Super7 CNC conversion uses a type AC5707645251 size 23 stepper motor that came from Arc Euro Trade (I think they no longer stock these). Googling it says that it's rated torque is 180Ncm - what a ragbag of units! But that's 1.8 Nm. There's a 2:1 toothed belt reduction between motor and leadscrew. I have never had a problem with inadequate torque either surfacing or screwcutting. The leadscrew pitch is 1/8" so slightly larger than yours. I can't see why more torque would be a problem? The driver is the ubiquitous 2m541 type, also from Arc, supply ~40V and probably running peak current of 2.5A or so.

Thread: G-gem gib or g-golf -gib?
09/10/2018 09:09:38

A sailing boat can tack or gybe, the latter pronounced jibe. The strip that makes my machine slides snug for me is a jib strip but spelt with a g.

Thread: High Voltage influence on a remote control
08/10/2018 12:13:48

I'be been giving some further thought to this.

  1. The receiver in the trap on the tower must be integral to the trap? So it is hard to move it to a different place.
  2. I assume the tower must be made of steel for strength?
  3. The tower is ~20 feet from the power line (or 20ft high above ground?)
  4. I've tried looking on both Google and OS maps, can't see any pylon runs in the vicinity of Pevensey though I'm sure there are some. Are they pylons or poles? Likely to be higher voltage if pylons.
  5. The 50 Hz electric field strength at the top of the tower could be significantly greater than at ground level, because the tower is likely all at earth potential.
  6. Radio devices can be affected by 50 Hz electric fields. I have observed this on my own VHF car radio as noted above and also in troubleshooting noise in a broadcast receiver system. Symptom of bad design.
  7. One cannot rely on cheap modern electronic devices being designed to reject large fields at the input - RF skills are in short supply, often the designers just buy an off the shelf chip and follow the application circuit, and the interference case is most unusual! Not that they probably do much testing anyway - often the antennas are truly awful.
  8. So we can't rule out sensitivity of the receiver to the 50 Hz electric field.

However, it should be easily possible to screen the unit from these fields if they are the problem. What you need is a horizontal conducting metal plate above the trap earthed to the top of the tower. At 50 Hz this will create a field-free zone between the plate and the top of the tower and so screen the receiver. As long as the gap between the plate and the receiver is a wavelength or so - ~75 cm - it should have little affect on the wanted RF (probably 433 MHz) . The plate could simply be a sheet of chicken wire on a wooden frame, I'd have thought a meter square - I assume that the trap chucks out sideways? Simple to do, could be worth a try.

Thread: Help wanted in sourcing sewing machine motor capacitor
07/10/2018 15:10:06

That looks more like a battery symbol to me, though what it would measure I don't know. I think the way these meters measure capacitance is to charge it through a resistor or constant current and measure the time to reach a set voltage. Once you have a micro and the ability to measure time/frequency it's easy. Nothing like as accurate and versatile as the old Wayne Kerr LCR bridge I used to use though.

Thread: High Voltage influence on a remote control
07/10/2018 12:28:36
Frankly I wouldn't bet on one of the modern cheap remote control receivers at 433 MHz having much of a tuned front end! It didn't seem like my car radio had one either.
Thread: WARCO Reversing Problem
07/10/2018 11:06:04

How many people have actually done any machining in reverse? The only thing I use reverse for on my S7 is when using an old toothbrush to clean the spindle nose threads so the grot drops off the end rather than being screwed on to the register.

Thread: Boring head capacity
07/10/2018 11:01:10
Posted by JasonB on 07/10/2018 10:31:22:
Posted by John Haine on 07/10/2018 09:43:02:

Lathe or mill, surely irrelevant. Max diameter determined by max safe offset of the moving part in its dovetails. Personally I would not feel comfortable with it further than half the head diameter. Then you can add on the offset of the tool hole, or if you want a really big hole stick the tool out sideways in the tr

That does not make sense, first you say Max dia is determinded by the dovetails and then you say put the tool in the side to get a bigger dia which mean max dia is being determined by the tool.

Even if using the end holes the type of tooling can be used to gain more diameter where length is needed, look at these two same offset of the head but 1+" increase in diameter

Edited By JasonB on 07/10/2018 10:35:34

Obviously the tool and its position affects the maximum diameter and with a long transverse tool it can be as big as you like in principle and given enough room on the lathe. But the limiting factor once you have decided where to place which tool, and given the size of your lathe, is how far out the movable part of the head can go without losing rigidity. For me that's about half the length of the dovetail, unless taking very light cuts..

07/10/2018 09:43:02

Lathe or mill, surely irrelevant. Max diameter determined by max safe offset of the moving part in its dovetails. Personally I would not feel comfortable with it further than half the head diameter. Then you can add on the offset of the tool hole, or if you want a really big hole stick the tool out sideways in the transverse hole.

Thread: Carbide threading inserts.
07/10/2018 07:17:22

I got a very nice internal threading holder and tips from JB at a show last year.

**LINK**

Thread: High Voltage influence on a remote control
07/10/2018 07:14:07

I used to have a car radio that would cut out when listening to fm and driving underneath hv power lines. I had to switch it off and back on to get the sound back. I suspect that it had a front end which allowed quite high 50 hz signals through to the active devices. Generally speaking receivers haven't got any better as devices get smaller and cheaper, especially with these license-free radio remote controls. It may be that the unit simply is picking up a rather strong 50 hz signal from the electric field and has no effective filtering to keep it out of the actual receiver. Does the unit have an external antenna socket?

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