Member postings for Roger B

Stuart,

Proxxon offer blades for the FET for non ferrous materials including the fine tooth 28730:

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Roy Amsbury built a 120cc V8 with a silver soldered brass crankcase. This was featured in ME starting 3rd May 1991.

In John Smith's milling machine thread I drilled a 3mm hole in steel with my MF70. 636 people looked at that video over 5 days. No one commented. I could make a spindle nose adaptor for my FD150 and make a sawing trial at 5000rpm with a 100w motor (I might anyway because it might be useful for me) but will it change anyone's opinions, probably not.

I am a happy Proxxon user and I understand the limitations of their machines, I have in the past discussed price/performance balance with their technical department as I have with Sherline. That is why my FD150 has Sherline chucks.

I checked last night which saw blade I was using and it is actually the HSS version rather than the carbide one.

If you choose the Proxxon FET you will have the possibility to use an abrasive disc or one of these small saw blades. 50mm diameter rather than 80mm will give a useful reduction in cutting speed for the saw blade.

What thickness of steel are you planning to cut? I have seen 0.1mm mentioned.

The 50mm Proxxon solid carbide blade 28 011 will certainly cut steel although the KS 230 may run a little fast.

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This is one slitting a steel 'taperlock' style bush. They a quite useful as small slitting blades.

There should be a threaded hole in the end of the quill (the bit with the graduations on it). The thread on the hand wheel goes into this and pushes the tapered part out as you wind the quill back into the tailstock. If the chuck has been in place for some time some heat may help.

Those are some trickey castings. I'm still following and enjoying

I would say that the damage to the toolpost is minimal. Hopefully the chuck jaws can be cleaned up with a fine file. The outer gripping surface is seldom used and 3 jaw self centering chucks are not high precision components.

The long rectangular bar is mainly to protect the leadscrew, some people me included, use it to mount travel stops. Hopefully you can repair it with Araldite or similar.

As an experiment I drilled a 3mm hole in a piece of 3mm thick probably mild steel with my MF70. The drill was a new Proxxon shortseries drill from one of their sets. Speed was minimum, 5000rpm, the feed was wind as fast as you can till the motor starts to stall. With more consideration given to the feed it would probably have been better but it worked. Here is a video clip:

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Going bigger than 80mm may not bring you much. Unless you have a low speed attachment the minimum speed is 250 rpm. Clearance over the bed is 65mm so you will need to check the clearance of the jaws. This is an 80mm blank held in the standard 80mm chuck.

Having read the OP I thought I would see what runout my lathes would show. Here are a couple of shakey handheld videos. As I had a setup in the chuck of the Hobbymat I made the measurement on the chuck mounting flange. This is not very smoothly machined and as I realised afterwards it has an 0 stamped in it to position the chuck. The mearurements were made with a 1 micrometer resolution TESA indicator mounted on a Mitutoyo magentic stand. The runout is around 10 micrometers and I was not able to see any deflection with hand presure on the chuck.

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I repeated this with my Proxxon FD150, this time measuring on the chuck register. It was difficult to get the indicator in place. The runout here was around 5 micrometers and I got a couple of micrometers deflection when pressing on the spindle nose.

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The rear bearing is a sliding fit on the shaft so that the end play can be adjusted with the two nuts. There is no need to remove the rear bearing before taping/pulling the spindle out.

Why do you feel that you need to replace the bearings?

Looks like you are getting better running now Any chance of a video?

I will be interested in how you get on with the 1831 carb. Like the road roller engine it seems that very few 1831/Wallaby engines are actually used in locomotives and vehicles

Another show and tell This is my 25mm bore 50mm stroke engine running with a 4.3 mm bore model aircraft type barrel carb. I could get a higher output with a bigger carb but it was more 'touchy' The tank is around 30 mm below the carb.

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IIRC this engine is around 35cc If you are looking at slow speed running a 5 or 6mm venturi will be fine. For power you might need something like 8mm but that will depend on the valve sizes and cam timing.

Have you checked the valve timing? The exhaust should open towards the end of the firing stroke and close just after the next top dead centre. The inlet should open slighly before the exhaust closes and close as the compression stroke is starting. If you are out a tooth or so you can get pressure rather than vacuum in the inlet pipe which rather upsets things.

I have been running an 5.5mm bore SU type carb on a 12cc twin. The piston doesn't have a damper but is fairly stable:

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Splendid work on the Mc Donald

Howard, all the work on the diesel engine as well as petrol and diesel fuel injection systems is on Model Engine Maker. So as not to take over this thread I am happy to continue discussions on there.

https://www.modelenginemaker.com/index.php

You need to be a member to see the pictures. I initially ran the engine as a petrol engine with a different cylinder head to prove the porting would work. In this form it would run reasonably slowly but I don't have enough space for a big enough flywheel to allow the diesel to run at low speeds, the compression pressure is around 30 bar.

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Congratulations

I would suggest that you raise the fuel tank so that the fuel level is maybe 1/2" below the carb. There may not be enough suction at low speeds.