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Member postings for stephen goodbody

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

Thread: Milling - What am I doing wrong
03/03/2017 17:54:09

I suspect that the workpiece is bowing due to internal stress relief, a common problem with bright mild steel due to the way it's manufactured (rolling). As you remove metal from one long surface there will then be an imbalance in the material's internal stresses which causes the material to bend.

The easiest way to overcome this is to remove most of the metal from opposite sides of the workpiece but leave some remaining on both sides - "roughing". You will likely still have a slightly bowed or a slightly tapered result at the end of the roughing cuts. Then remove the remainder on each side to finished dimensions.

The alternative is to heat soak the steel at high temperature (cherry red, if memory serves) for about 1 hour per inch of thickness and then let it cool gently to room temperature. This is known as "stress relieving".

Good luck,



Edited By stephen goodbody on 03/03/2017 17:54:45

Edited By stephen goodbody on 03/03/2017 17:55:23

Edited By stephen goodbody on 03/03/2017 17:55:53

Thread: Burnerd Miniature Quick-set Toolpost Type TP
01/03/2017 14:14:08

Toolposts, boilers and stainless frames all in one thread. Quite the development!

Looking back, my apologies for repeating the same information as others (patent number and Twin Sisters). I should have properly read all of the posts before adding my own.

Regarding my experiences with the Burnerd, unfortunately I really can't compare it with other small lathe toolposts as this is the only one I've ever used.

I can confirm that I've never had a problem with the toolpost rotating of its own accord however. There's a nut (probably 1/2" BSF, but I'd need to check) that tightens the center bolt into the T-slot, this is more than capable of stopping the post from rotating. All that the ball-ended handle does is to clamp the toolholders within the post, it does not clamp the post to the top slide.

Regarding the grub screws in the toolholders themselves, these are 2BA and keep the tools in place without problem in my experience. They also allow the tool tip height to be adjusted. As with all grub screws, the Allen key hexagons in the top ones tend to clog with swarf but can be easily cleaned out or replaced with cheesehead screws (which is what I've done in a few cases).

Regarding tool height adjustment, it's important to remember that my lathe is a round-bed and hence most of my adjustment is most easily done by rotating the saddle around the bed. Hence I really don't use the grub screws for height adjustment except when initially putting a new tool into a holder.

I have a decent selection of toolholders, but unfortunately managed to break one of my boring tool holders a few years ago when inserting a tool. A fatigue crack had evidently developed at the bottom corner of the tool slot. It could be mended, but fortunately I have another and so have not had the need so far. That will be a project for some future time, I'm sure.

It's important to remember that my lathe use is hobby only, and I'm one of those people who would rather use what they've got rather than buy new. I get a perverse satisfaction out of using old tools (my lathe is over a hundred years old, after all!) and have often found that new tools are better in some ways and worse in others than the ones they've replaced. However, after nearly 40 years using the same equipment I probably know the limitations (mine and the tool's) and feel sure that those limitations are likely more than would be the case for most others

I've recently made a new set of injector cones (very fine tolerance work) and last weekend was taper-turning and taper-boring some 6-inch lengths of 2.5 inch steel pipe for a traction engine chimney, so for me the lathe and tooling works just fine.

Best regards

28/02/2017 23:34:13

I see in some of the above that Mr Austen-Walton may have been involved. If memory serves I believe he had a 5 inch loco designs published in ME, probably in the 50's or early 60's at a guess. The loco name was Twin Sisters.

Best regards


28/02/2017 23:29:51

The stamped patent number is 655.793 Michael.

Best regards


28/02/2017 21:40:24

I'll have a look tonight Michael.

Best regards

28/02/2017 21:21:24

Hello Ken,

My George Adams round-bed lathe has this toolpost system - I've been using it for nearly 40 years and wouldn't change it for the world.

See the following links for pictures and a write-up:

Best regards


Edited By stephen goodbody on 28/02/2017 21:21:35

Thread: Bending 1/8 pipe
28/02/2017 20:59:47

Hello Paul,

Generally it's best to start with a longer length of pipe than you need, make the bend, and then cut the pipe back to where you want your nipple to be. If the nipple is already soldered onto the pipe then the job is more difficult because you have less leverage for bending.

Assuming this is copper, the way I normally do it is to make a simple slotted mandrel from a piece of scrap brass rod. Chuck a length of rod in the lathe and machine a slot a tiny bit wider than the pipe diameter and to a depth of at least 3/32" but preferably 1/8" deep. The width of the slot should be such that your pipe slips in and out of the slot easily but doesn't waggle around. The root diameter at the bottom of the slot should be your bend's desired inside radius. If in doubt, err on the side of a slightly smaller root diameter.

Anneal the pipe where you want the bend to be, put it into the slot, and gently push with your fingers to start the bend. As soon as the pipe begins to work harden (stiffen) gently ease it out of the mandrel and re-anneal. Repeat until the bend is finished to your satisfaction.

The above works because a pipe can only flatten in one direction if it can simultaneously stretch in another. The side walls of the slot prevent the pipe from widening and hence prevent the pipe from flattening. The pipe will tend to want to stick in the slot, especially if you bend too much between annealings, so beware. An improvement on the above is to make a two-piece mandrel where one half screws into the other to leave the 1/8" slot between. You can then partly unscrew one side of the mandrel to remove the pipe after each bend, overcoming the potential problem of the pipe jamming in the slot and being difficult to remove after bending.

Good luck,

Steve Goodbody



Edited By stephen goodbody on 28/02/2017 21:01:18

Thread: injector problems still
14/02/2017 14:21:18

Thanks Ron. It really does sound to me like there's either a tiny air leak in the water side or that there is muck is the tank that is being carrier into the injector water line.

For the air leak theory, you can try the 'wiggle' test that I mentioned earlier and see if you can get the injector to knock off. To narrow down the leak's location you may be able to pour water over sections of the suspect piping or valve and see if that temporarily cures the problem - when you pour water over the problem the water gets drawn into the pinhole and seals it temporarily. A squeeze bottle with a small pipe nozzle to direct the water flow is a good tool for the job.

For the muck theory, step one is to flush out the tank as best you can using hot water. If you haven't already done so, make up a removable filter for the injector supply pipe using fine brass mesh. It's also a good idea to use the same mesh to make up a removable filter for the tank filler hole to help prevent muck from getting into the tank in the future.

Best of luck,


14/02/2017 13:16:28

I know how frustrating these things are. The really good news is that you know that the injector worked before you got it on the track - that's much better than one that won't work at all!.

My strong suspicion is that there is a tiny air leak somewhere in the water supply (copper piping and unions, flexible piping and connectors, water valve glands etc) that's opening up due to the the motion of the engine. It doesn't take much (and you may not even be able to see the hole or gap) but that would certainly cause the problem you are having. An alternative possibility is that there is muck in the tank that's getting stirred up and sucked into the feed on the run, but I think that the air leak is more likely from what you're saying.

As a suggestion, I would be inclined to steam it up in the steaming bay (or at home) and then wiggle the piping, connectors, valve stem etc and see if you can make the injector knock off. If you can then you've found your culprit.

One thing that is not totally clear to me - does the injector only fail when the loco is running on the track? In other words, when it fails and you bring it back to the steaming bay, does it then pick up fine without your doing anything else to it?

Good luck Ron,


13/02/2017 22:53:02

A couple of thoughts Ron:

- Was the boiler pressure the same when it was working and when it was not working? Most injectors have an operating pressure range and won't work reliably above or below that range whatever it may be.

- Any chance that the water supply could have warmed up? As you know, most injectors become unreliable with warm water.

- If a tender loco, any chance that the feed pipe could have been kinked, worked loose, or even melted(!) during the run?

As an aside I once had a problem with a new injector that wouldn't feed reliably and would mostly dump water from the overflow, especially at the low end of its expected range (although it would occasionally work okay and could be made to feed by blocking the overflow). The problem turned out to be that the annular gap between the steam cone and combining cone was too large. After carefully removing some of the 'step' from the steam cone, so that the cone sat closer to the combining cone, all was well. About five thou was all it took.

Good luck

Steve Goodbody



Edited By stephen goodbody on 13/02/2017 22:53:29

Thread: Allchin Differential Lubrication
04/11/2016 14:10:47

Many thanks once again.

Jason, it does indeed look like I know have access to the Traction Talk forum, your help is very much appreciated.

Best regards

25/10/2016 23:19:18

That's very kind of you - thanks Jason.

Best regards


25/10/2016 18:04:57

Hello Jason,

As previously mentioned, I've registered for Traction Talk but have been unable obtain the permissions needed to post or reply to a thread on any of topic sections. I've tried several times contacting the forum owner, using the contact details provided by the website, but have unfortunately had absolutely no response or reply.

Do you happen to know if the Traction Talk forum has closed to new members? If not, can you (or anyone) perhaps recommend or suggest what the issue may be?

Thanks in advance for any help or suggestions,


12/10/2016 18:45:24

Thanks once again to all who've replied.

Jason - I wasn't aware of Traction Talk and will indeed post the same question there. I've registered but don't yet have the permissions needed to access the forum or post a thread.

NIgel - it sounds like you saw the 'problem' (if it is one) in advance. Based on your own engine, do you think it's feasible that simply squirting oil into the annular gap between the winding drum and the toothed driving plate will stand a chance of getting at least some onto a bevel gear or a pinions such that it would then be spread to the other gears as the differential rotates?

To anyone else reading this who has first-hand experience of the Bill Hughes design, I would very much like to hear your approach to lubricating the Allchin differential.

Best regards


10/10/2016 13:31:35

Many thanks for the replies Jason and Chris,

Focusing on question 2, and specifically the Bill Hughes Allchin design, I would greatly like to hear from anyone who has built and runs one of these engines and to find out how they lubricate the differential pinions (aka compensating center).

The drawings show oil holes for the pinion shafts, these appear to be lubricated through the two driving pin holes in the wheel hub. However I can see no way of getting oil to the pinion gears themselves short of blindly squirting it into the gap between the winding drum and the toothed driving plate.

Any help is greatly appreciated.

Best regards,


06/10/2016 21:04:42

Hi all,

I'm new to this forum and so apologize if I'm repeating an often-asked question, but does anyone have any guidance with respect to lubricating the differential gears on an Allchin traction engine?

The engine is the Bill Hughes design doubled-up to 3 inch scale, and the specific questions are:

1. Do you lubricate the differential?

2. If so, how? (short of removing the rear wheel and stripping the unit down)

3. Is it best to use grease or oil?

The engine is not hard worked but it does get used every few weeks through the summer and clocks up perhaps 20 miles a year.

Thanks to all,

Steve Goodbody

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