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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: Proxxon mf70
05/01/2022 08:51:38

I have an MF70 and made this video of drilling a 3mm hole in mild steel as a 'Show and Tell' for another thread on here:

**LINK**

I think you will find it a pain to use for regular drilling due to the screw feed rather than lever feed. I have a TBM 220 for small drilling work.

**LINK**

In other threads people have spoken highly of the BFW 40/E system but I have no personnal experience of it.

**LINK**

Thread: (again) buying new European made lathe
14/12/2021 15:52:19

Another posibility is Teco who still produce the Hobbymat:

**LINK**

This is also available from Pro Machine Tools who advertise on here:

Thread: Best way to make valve guides
22/11/2021 20:28:04

I think that the answer depends on how you cut the valve seat. If it is cut from the valve guide bore the concentricity of the guide doesn't matter. if it was cut from the the bore in the cylinder head then concentricity is important.

Thread: Best place to find a Hobbymat MD65?
05/11/2021 13:22:38

That looks to be in excellent condition smiley What accessories did you get? I can see the 3 jaw chuck and the drill chuck as well as what looks like the milling angle plate in the background.

Thread: Is it possible to machine a lathe more accurate than the one you machine it on? If so, how?
29/10/2021 20:01:16

I think, and this is seriously stretching my memory that L T C Rolt produced a book on the development of machine tools and especially averaging devices to improve lead screws (I am prepared to be completely wrong on this ;-( )

Thread: Mc Donald Model tractor
28/10/2021 10:28:20

Looks good yes I hope there are no hidden faults.

Thread: Rumely Oil Pull engine
15/10/2021 10:57:17

Looks and sounds great to me smiley It is interesting that it seems to run better under load. Maybe the compression ratio is a bit to high for the weight of the flywheel?

Thread: Cutting Brass Sheet
02/09/2021 15:45:37

This is the closest example I have of what you would like to do. This was 0.3mm Phosphor Bronze. I have cut up to 3mm thick Brass.

**LINK**

01/09/2021 15:20:57

I use one of these small Proxxon saws with a HSS blade for cutting brass, aluminium and thin steel. You would need to check the clearances if you are working with larger sheets. The fence will go either side of the blade.

saw 1.jpg

 

saw 2.jpg

 

 

Edited By Roger B on 01/09/2021 15:22:07

Thread: Mc Donald Model tractor
26/07/2021 11:47:46

My engine is only 20cc so those valves are a bit big but that will hopefully help the volumetric efficiency.

25/07/2021 17:54:52

I'm still following and enjoying smiley

I decided to reduce the doubt for my two stroke diesel by using a commercial reed valve from a moped/scooter. This was not expensive however if you have a dealer/workshop near you you could see the various sizes and shapes available.

251 commercial reed valves.jpg

252 possible fit 1.jpg

252 possible fit 2.jpg

Thread: Centaur Ignition Coil
23/07/2021 15:31:30

The smaller size traditional motorbike coils are available from places like here:

**LINK**

I have used them sucessfully on my model engines.

Thread: Carb for single cylinder engine
02/07/2021 11:42:44

The fuel pump started out as a piece of 20mm square aluminium. I have also built a larger 25mm version but the delivery was too much for this engine. The diaphragm is cut from 1mm Viton sheet using the clamping ring as a punch guide. I decided to use a ball and socket at the rocker end of the pull rod so it would stop pumping against a closed outlet (needed for another application). It is driven by an eccentric mounted on the camshaft drive gear. The inlet and outlet are gravity ball valves with 3mm stainless steel balls. Tiny cross shaped pieces limit the movement to 0.5mm.

299 trial fitting.jpg

309 trial fit on the pull rod.jpg

312 valves in place.jpg

716 improved cooling pipe layout.jpg

fuel pump.jpg

02/07/2021 09:34:12

I made a tinplate float 26mm diameter and 30mm long many years ago. The material was the thinnest plate that the local model/hobby shop had, maybe 0.2mm. The ends were spun in the lathe and the body was rolled around a former. It was soldered up with the minimum possible solder to keep the weight down. The finished item weighs 6.5g and floats reasonably in alkylate fuel (I think the density is similar to pump petrol).

It never worked due to my inability to make a suitable valve at the time. I decided to use an overflow system for my model SU type carb as this would have needed an even smaller float and valve.

Tinplate float 1

Tinplate float 2

Thread: Easy Start
28/06/2021 19:22:36

No one will bother with Easystart if the engine will start without it. If you have to use easy start the engine already has significant problems. So no it is a myth. if you have to use easy start you will always need it, the engine is already past it's best. I will put in a caveat for very low temperatures but my 13 year old diesel car started instantly having been standing outside in -17°C for several days. The idling fuel consumption was ~4 times normal until the gearbox warmed up but we could drive away.

Thread: Hinckley C
16/06/2021 15:10:00

The problem at Taishan 1 appears to be within normal operational parameters:

**LINK**

08/06/2021 20:00:14

The problem is that the gas cooled reactors are much bigger than the water cooled ones and require more materials and end up with more activated materials to deal with at decommissioning.

There is a benefit that melting of the cores in case of accidents is less likely due to the lower energy density but where is the sensible balence ???!!!

Thread: Mc Donald Model tractor
29/05/2021 16:13:30

Excellent smiley

How many teeth are on the ratchet wheel, in other words what is the reduction from crankshaft speed? 3.2 x 3.4 mm is quite a lot of oil.

Thread: Hobbymat MD65 - help figuring out accessories (photos)
26/05/2021 11:58:40

As you say screwcutting takes care but it is possible.

The voltage regulator you show will not work with an induction motor as fitted to the MD65.

The slow speed system helps but is not the complete answer. The problem is the stopping time, the standard motor has quite high inertia and takes a while to run down when just taking a light cut.

Two possible solutions:

1) Make a handle to fit in the back of the spindle and turn by hand for screwcutting.

2) Change the drive to a 3 phase motor and inverter as described here:

**LINK**

Thread: What is a Lug Sweater?
20/05/2021 12:11:17

I think this is what he is talking about:

**LINK**

I borrowed something similar from work many years ago when rebuilding my bathroom. Wonderful, no flames, no smoldering floorboards.

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