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Member postings for Roger B

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

Thread: Testing for isolation
04/02/2019 13:00:49

If you beleive you have isolated correctly and are prepared to touch it with your hand a short circuit with a screwdriver will be no problem. If you have made a mistake it may save your life. Belt and braces.

Thread: Proxxon MF70 went bang
04/02/2019 11:39:29

There was apparently a design change in the MF 70 motor so the detail of the part number may be important.

This company offers a possibility:


The parts list is here if you don't already have it:


I have removed the motor from my (probably newer) MF 70. There is a screw either side of the motor and then you have to pull the motor out of the coupling. The older version appears to be more like a gear.

005 drive motor and speed control board.jpg

006 spindle drive coupling.jpg

Best regards


Thread: Form tool to cut big end / main crank bearings.
11/01/2019 14:48:40

Is the crankshaft cut from solid or a casting?

Are you doing all the turning between centers?

Is it possible to support one end in a 4 jaw chuck to improve ridigity?

Thread: Siezed Drill Chuck in a Tailstock
10/01/2019 15:29:46

This is going back a long time but I think it was quite deep, 25-30mm. If you have a MT1 something with a tang on it it will give you an idea of how deep the taper in the quill is.

10/01/2019 14:51:42

OK. Another option (which was done on my brother's slightly later version of the same lathe) is to drill through the quill from the handwheel end which allows the use of a 'knocking out' bar.

10/01/2019 14:33:34

I would make a couple of spacers to go between the tailstock body and the back of the chuck and then use the feedscrew and handwheel to try and push the chuck out.

Thread: 540 Motor as a generator
09/01/2019 10:41:48

I have used similar small permenant magnet motors as generators for my IC engines. You may find you need to use a belt drive to increase the speed, this was common in full size steam generating stations.

As a quick check you could drive one of the motors with your lathe of drill and see what output you can get.

This video is my 3cc engine lighting a few lamps:


Thread: Hobbymat MD65 carriage adjustment troubles
11/12/2018 08:03:19

If you can manage German these people also claim to offer spare parts:


There is also a downloadable (German) Instruction manual and parts list at the bottom of the page

Best regards


10/12/2018 14:08:39

You should be able to get a new bed. Essel Engineering still have some parts although they are no longer on the website:


As the same lathe is still made and imported by Pro Machine Tools they may also be able to help:


Best regards


Thread: J Ridders 4 stroke I/C Engine
05/12/2018 13:04:04

Is the compression good? You should be able to 'bounce' the piston off the compression.

Best regards


Thread: Hobbymat Saddle Adjustment
10/11/2018 16:41:48

The manual I have shows a fine feed system that screws in above the quill and gives a fine screw adjustment (it must have a thrust bearing somewhere) but I don't have any real details. I just reach up and wind the handle smiley

09/11/2018 12:48:37

The middle screw forces the clearance to open and the outer two pull it shut. If you unscrew the middle screw do you still have too much free play or does the saddle lock up?

If you still have free play gently tighten the two out screws until the saddle is just tight. You may need to experiment to make sure that both screws are having an effect and it is not just tight at one end. Then gently tighten the middle screw until you have free movement without excessive play.

If the saddle locks up gently loosen the two outer screws until it is free and proceed as above.

You should not need more than finger pressure on a standard length Allen key for the above adjustments.

Best regards


Thread: Wyvern cylinder head sealing
08/11/2018 11:01:03

This is the 'bounce' I get on 25cc engine with single 125mm flywheel which is nearer your size.

Do you get suction at the inlet port when you turn the engine by hand?

Looking at the drawing on the Hemingway website the valve cages have ports in the side. Is it possible to assemble them the wrong way round?

Best regards



Edited By Roger B on 08/11/2018 11:02:32

07/11/2018 07:28:09

How are you turning the engine to try and start it, by hand or with an electric drill?

Are you sure you are turning it in the correct direction (ref. fuel coming out of the carb air intake)?

Is the exhaust passage free? Pressure in the cylinder when the inlet valve opens could also cause blowback.

Best regards


06/11/2018 10:05:39

The compression does not have to be high but there must be no leaks. The usual description is 'bouncy' or 'springy'. You should be able to flick the flywheel in the direction of the compression stroke and it should bounce back.

Are you using a homemade or commercial sparkplug? Do you have a spare? DOA is not unknown.

Have you checked the complete valve and ignition sequence with the sparkplug resting on top of the engine so you can see the point of firing.

Inlet opens around TDC.

Inlet closes just after BDC

Spark plug fires just before TDC

Exhaust opens just before BDC

Exhaust closes around TDC

What fuel are you using? Old petrol can have lost most of it's volatile components.

Best regards


Thread: Another what is it
01/11/2018 07:06:41
Posted by Lambton on 31/10/2018 11:22:11:

A German engineer I once worked with contemptuously referred to it as "a Frenchman" - which says it all really

Here, Switzerland, an adjustable spanner is known as an" Englander"

Best regards


Thread: Micro drilling
17/10/2018 15:09:38

Have you checked the points of your drills with a magnifying glass? The first cheap micro drills I bought had non existent points. The Titex ones I am now using are excellent.

10/10/2018 14:57:42

How big and how deep? I have got down to 0.2mm using a 0.5mm centre drill for spotting.

Thread: Recommend an er11 chuck and collets
04/10/2018 13:55:24

I purchased my ER11 collet chuck and collets from CTC. They are based in China but I believe they have European warehousing. The quality was fine for my needs.


I also have a small, 0.2-3mm, drill chuck from RC in Luxembourg which I have used down to 0.2mm.

376 the chuck will hold them.jpg

Best regards


Thread: Hut Consumer Unit & MCB Question
28/09/2018 10:30:56

To determine if the Installation meets the requirements of BS7671 would require PSCC (prospective short circuit current) and EFLI (earth fault loop impedance) measurements. The type of cable used is an open discussion point, SY is not recognised in the Wiring Regulations. This however is not your present problem.

MCBs have two operating elements, a magnetic trip to deal with short circuit conditions and a thermal trip to deal with overloads. Under short circuit conditions they do not discriminate well with fuses or MCBs of different ratings.

The website information for the traverse drive states that it has overload protection. This should protect against you switching direction without stopping. Either this is faulty or there is another fault with the system (such as the switch itself) putting a short circuit on the supply.

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