By continuing to use this site, you agree to our use of cookies. Find out more

Member postings for John Rudd

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

Thread: Amadeal VM25L R8 Milling Machine
23/06/2022 16:53:38

Nice try.....now to address the over hang, you could make some machinists jacks that would fit underneath the bar at either end....

A job for another day...

Thread: Help Needed - Reversing a 240 Volt Motor
18/06/2022 09:30:19

Cap start with cs
Here’s a motor with a cap start with a centrifugal switch…,,

 

Reversible cap start
Here’s the wiring for the same but with a reversing switch added….the switch is a double pole type with 2 positions…it will have six connections  to it…Usually the centre connections are wired with the capacitor/one end of the start winding. The outer connections are cross connected, with the Live and Neutral at one set of connections..

 

Edited By John Rudd on 18/06/2022 09:33:32

Thread: High temp varnish
17/02/2022 12:55:57

Duncan,

You could use varnish as used for transformers and motors from Brocott.co.uk

 

https://brocott.co.uk/electrical-insulating-air-drying-varnish-250ml-clear/

Good for temperatures in excess of 100C and they sell in small quantities…

Edited By John Rudd on 17/02/2022 12:58:07

Thread: (Another) Mini Lathe Speed Controller Problem
17/02/2022 10:55:29
Posted by John Haine on 17/02/2022 09:37:23:

Motor controllers don't necessarily react happily to the circuit to the motor being interrupted whilst running, your fuse could be a bad move...


KB electronics, the designer and manufacturer of these boards, recommend the fitting of fuses, line side and armature side, obviously of the correct rating for the motor being served by the controller.


15/02/2022 21:34:31

Philip,

I sent you a private message.

IanP,

The description of the controller discussed in the article is based on a PWM based controller using mosfet power devices rather than the KB clone which is Phase angle control using a pair of scr’s in a full wave bridge.

Thread: Help wanted, DC motor speed controller issue
31/01/2022 14:50:55

Russ,

The following notes might aid your fault finding...

The component designations are for a KB controller, they may be different to that of the Best item...

(A) Check resistance across L1 and L2. Reading should show infinite or open circuit. Be sure to reverse leads across L1 and L2. Reading should still be infinite. Measurement values shown below are approximate only .
If "0" ohms is observed, check field diodes D4 and D7.
With (+) lead on L2 and (-) lead on L1,
If .66 ohms is observed, replace diode D7
If .56 ohms is observed, replace diode D2.
With (+) lead on L1 and (-) lead on L2,
If .66 ohms is observed, replace diode D4
If .56 ohms is observed, replace power diode D1.
(B) Check resistance across F+ and F-. With (+) lead on F+ and (-) lead on F-, reading should be infinite. With reversed leads, reading should be 1.2 ohms. If reading is less, check diodes D4 and D7 (see above).
(C) Check resistance across A+ and L2. Reading should be infinite. If reading is less than infinite, check SCR2.
(D) Check resistance across A+ and L1. Reading should be infinite. If reading is less than infinite, check SCR1.

27/01/2022 13:08:41

The Chinese lookalike boards similar to the KBIC control boards are essentially copies using thru hole components, although some later derivatives use smd devices too.

The mains AC is used to drive a full wave bridge rectifier comprising 2 S*025L thyristors and similarly rated diodes.A third diode is connected directly across the output. The F+ and F- supply is generated using two low current diodes( typically around 1 amp).

The full wave bridge uses phase angle control with a zero crossing detector to generate the speed control.

A startup ramp is generated using a resistor and capacitor network that is adjustable to give a soft start, current overload sensing and motor load compensation is also featured on these boards.

The Seig speed controllers are similar but principally operate the same way.( are some subtle differences in how the 12v rail is provided).

Repairing these boards is not for the faint hearted.
Be also aware that the scr/diode devices that are heatsinked on the KB boards have isolated tabs, the Best controllers I’ve encountered are isolated using mica washer sets, the devices not having isolated tabs…Using the wrong type of device can result in failure of neighbouring parts.

Fake parts abound, beware where you buy replacements from

Edited By John Rudd on 27/01/2022 13:09:11

Thread: Smart meter
21/01/2022 14:15:39
Posted by duncan webster on 21/01/2022 13:56:30:

Taking meter readings every month is not exactly onerous, and I know tumble driers use a lot of power, so I still don't see why smart meter is to my advantage…..l

Smart meters in my opinion do not help the consumer more like confuse….,

Its simple, you pay for what you use….If you live in a household lit up like Blackpool illuminations, then be prepared to pay a large bill…..

When I was a child, we were reminded, to close doors behind us and turn off lights on leaving a room….now as a bill payer I can see why…

Thread: SPG Tools in Hinkley
09/01/2022 18:20:29

http://www.sumore.com/english/cplist.asp?type=2
 

Edited By John Rudd on 09/01/2022 18:21:16

Thread: SMR's a conundrum.
08/11/2021 11:44:37

I used to hate TLA's when I was working....

Thought I'd seen the end of them...sad

Thread: Chester 920 cross slide & Backlash
29/10/2021 16:52:15

I bought my spare belts from Beeline engineering in Milton Keynes, they worked out to be about £6-7 ea..much cheaper than the likes of Warco/Chester or even Ebay

 

The belts themselves are 5mm wide, the length did vary with machine....730 seems to stick in my mind...

Generally, If you have a 160XL Coged belt, you need a 5M720 V-Belt.
If you have a 170XL Coged belt, you need a 5M730 V-Belt.
Should you use a 5M720 V-Belt with the 170XL Coged belt the V- Belt will be too short.
Using the 5M730 V-Belt with the 160XL Coged belt, the V-belt will be too long.

Edited By John Rudd on 29/10/2021 16:57:24

Thread: Selection of AC transformer for Align Power Feed
23/10/2021 10:08:08

Go to your local electrical factors and ask for a 240-110V AC control transformer....

Dont know your location but here's an example....

https://www.rselectricalsupplies.co.uk/chint-multi-voltage-panel-transformer-150va-ndk150_1068

Thread: Chester 920 cross slide & Backlash
15/10/2021 08:39:38

The cross slide lead screw is M8 with a lh thread.

I had to make a new one for my 9 x 20 when the original snapped...Silver steel is good enough for a replacement..

Thread: Sieg X2 mini mill blowing fuses
21/09/2021 21:33:26

David, I sent you a private message....disregard it if the mill is new and under guarantee...

the power semiconductoir devices are thyristors ( scr ) and form part of a full wave rectifier bridge across the mains...one or more is defective if you read 0 ohms...

Thread: Cutting Steel Plate.
11/09/2021 12:00:06
Posted by John Baron on 11/09/2021 11:36:11:
Posted by noel shelley on 11/09/2021 10:18:29:

Sounds like fun ! Where are you ? Noel

Hi Noel,

I'm in North Yorkshire, near York.

You arent cutting up the 'lightning struck' Bilsdale tv mast are you? laugh

Thread: Vfd frequency Warco WM290 and WM280v
30/08/2021 15:23:09

FWIW,

I have a similar machine to the WM290 which originally came with a dc drive.

I changed the motor to a 2 pole 2800rpm 1.1kw 3 phase motor in an 80 frame size, it occupies the same space as vacated by the dc motor.

I used an Invertek vfd and set the max frequency to approx 72 Hz to give me the same spindle speeds as before.

I had no need to change belts or pulleys.

I used the existing speed control pot, rewired the FWD/REV switch to give the desired functionality for the vfd.

No additional switches or buttons.

Thread: re-magnetising magnetic base
07/07/2021 15:08:28

Folk who offer magneto winding services may be able to remagnetise it for you…

Thread: Is this a new scam?
30/04/2021 20:05:38

Selling on Ebay has now become less attractive....Gone are the fees paid to Paypal because the buyer pays directly to Ebay and they in turn pass on the proceeds to the seller after taking their cut...

From what I can gather Ebay fees are now more than what Paypal would have charged plus the selling fee for Ebay combined...making it less attractive to sell a low value item inc postage.

As a consequence of this, even buying would be less attractive too because sellers are likely to increase their prices to accomodate the rise in fees.

Thread: Variable rpm control for watchmakers lathe
19/03/2021 12:32:27

John Fletcher, pm sent...please.

Thread: HydroVane PR303E question
15/03/2021 15:34:05

 

 

I asked him "what work exactly has been done to this compressor as it is described as 'seller refurbished', did you use any spares?" (potential for mis-selling, not as described)

 

It wouldn't surprise me if it didn't sell....

 

Just got a reply on the instructions...£20....Greedy!!

Edited By John Rudd on 15/03/2021 15:41:10

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Support Our Partners
Dreweatts
cowells
Eccentric July 5 2018
Rapid RC
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest