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Member postings for tractionengine42

Here is a list of all the postings tractionengine42 has made in our forums. Click on a thread name to jump to the thread.

Thread: Boiler thickness and pressure
23/10/2014 12:28:18

If your model is to be insured and steamed in public, should it not be the case of establishing what design stress, joint factor and safety margins are acceptable to the boiler inspector and insurance company. Then the design can be worked out to meet their requirements and subsequently approved by them. In other words what code of practice do they accept?

Although you have done some testing to justify to yourself the safety of your design these are unlikely to be taken into consideration by your boiler inspector or insurance company unless very well documented and maybe also witnessed.

I am not familiar with the formulas stated above, the following table shows calculated tube thickness using a standard hoop stress formula (also typically used in pressure vessel codes). I have used some values suggested above for yield stress and joint factor and included a range of safety margins for comparison. Normally you would establish a design stress based upon material mechanical properties and operating temperature and use this in the formula.

Other considerations concerning boiler tube thickness will be a) does the boiler tube support any other significant structures like cylinders etc. b) what reinforcement is applied to openings/nozzles.

One method concerning openings/nozzles is to use an 'area replacement method', basically you take a section through the opening/nozzle, calculate the area of material removed then ensure that any reinforcing ring has at least the same section area. If the boiler tube is thicker than theoretical then the extra thickness above theoretical can be included in the calculation, for example, if the theoretical thickness is 0.05" and the actual thickness is 0.15" then there is a good chance that a reinforcing ring is not needed as the actual tube thickness already has sufficient strength. There is a specified method for determining the width of any reinforcing ring, I would have to look this up.

boiler tube calculation.jpg

Here's a useful source of information.

I hope this is useful info.


Thread: Sourcing deoxy copper plate
22/10/2014 10:32:56

There's a explanation of hydrogen embrittlement in copper here, in particular refer to text just above fig 16.


21/10/2014 12:16:37


Ye looks like C101 should be avoided as it's not oxygen free, apologies for my bum steer.

There's some comprehensive technical data on that Cup Alloys website, very interesting.


21/10/2014 09:16:22

Hi Fizzy

C101 is 99.9% pure copper, not absolutely sure if that's what you need but CES do sell it in 16 swg


Thread: Free Plastic
08/10/2014 00:20:56

Hi Graham

No desperation at all, please take your time.

I also sent a PM and payment on 5th and have not received any PM or confirmation.

No worries.


Thread: reamer
01/10/2014 09:42:10

Hi Nanande

15.5mm will probably be the nearest standard metric drill available.

Drilling 15.5mm the reaming 16mm will be perfectly OK. Less than 15.5 mm will not be desirable.

Where possible I prefer to bore the hole before reaming, I would drill 15mm, bore to 15.7mm them ream 16mm using cutting fluid when reaming steel.


Thread: Floor covering
28/09/2014 18:28:40

Originally I painted my concrete floor with industrial floor paint, after a few years the paint was very worn and concrete dust was becoming a problem.

I sealed all the worn areas and covered the entire floor with these interlocking tiles, I have found these very durable and comfortable, in my view worth the effort and money.


Thread: Really Silly Question - rpm facing off large diameters
17/09/2014 11:23:02


I think maybe Neil is referring to feeding across the work face manually, not on auto feed. So if you increase the rpm you have to turn the feed screw faster to maintain the feed rate in thou's/rev.


Thread: Free Plastic
15/09/2014 19:56:46

Hi Graham

I am waiting patiently, no hurry. Very much appreciate your time and effort, this is very generous of you.


Thread: Drill deep hole so on a lathe. I
15/09/2014 10:51:16


Jason is referring to Model Engineer magazine, not Model Engineers Workshop.


Thread: HSS cutting speed calculation
10/08/2014 08:01:41

Thanks Jason

That makes sense now and useful to know.

The article needs a revision.


10/08/2014 07:12:28

I was reading through Practical Engineer part 1 article on this forum  regarding cutting speeds but I am a bit confused.

The article states:

hss cutting speed.jpg

1" x 375 = 375 RPM for steel

1/2" x 375 = 188 RPM for steel

1/8" x 375 = 47 RPM for steel

What am I missing?



Edited By tractionengine42 on 10/08/2014 07:16:13

Thread: What did you do today? (2014)
04/08/2014 11:50:42


Very interesting hat posts, It's amazing the very diverse things you can learn on this forum.

I've only ever worn a woolly pompom hat. Soon I hope to be steaming my 3" scale Allchin traction engine, so that may be time for a suitable hat or cap.

The 1-1/2" scale drawing show a dummy displacement lubricator, for my 3" scale I decided to make a working version. Finished it over the weekend, here's the parts and the finished item fitted to the engine. Turned out quite well I think.

disp lub parts.jpg

disp. lubricator on engine.jpg


Thread: Making A bolt for my motocycle
22/07/2014 08:29:32

Hi Jamie

En57T is a high tensile stainless that is commonly used. it's no more difficult to machine than En16T/En24T and of similar strength. I bought some from M Machine, some other ME suppliers also supply this material.

Edit - I have not had any problem cutting threads using standard high speed steel dies using a good cutting lubricant. For turning I have used carbide tools but high speed steel can be used at low speed.




Edited By tractionengine42 on 22/07/2014 08:35:44

Thread: WM 16 Milling Vice
19/07/2014 21:42:20

Hi David

I am very happy with a 3 inch SOBA bought from Chronos about 10 years ago.

Here's a review

Here's Chronos website

I have no connection with Chronos .


Edited By tractionengine42 on 19/07/2014 21:43:12

Thread: Eccentric strap slack
14/07/2014 21:52:22


Any millage/benefit converting to white metal?

They would need boring out over size, cast in the white metal, re-bore to finished size. For small bearings could the white metal be tinned onto the bearing surface in the manor you tin solder?

Just a thought.


PS. some white bearing metal here

Edited By tractionengine42 on 14/07/2014 21:53:59

Thread: 3 ph motor conversion to VFD, any issues?
13/07/2014 16:52:39

Hi Everyone,

I have decided to change the motor on the mill to the one given to me by a friend complete with a VFD. Then their shouldn't be any power issues.

I have a Drummond model B lathe that I would like to get set up (some day). Now that I know I can run the old mill motor via a VFD with a base frequency set at 29Hz without modification, I will keep it for use on this lathe. Even running at reduces revs and possible lower power the old mill motor will be more than an acceptable match for the Drummond lathe.

I think this has turned out very well for my purpose.

Thanks again everyone that posted.


Thread: What did you do today? (2014)
13/07/2014 09:52:40

Neil, that layout look very impressive, As posted by Bazyle it's interesting to see a different aspect of model making. The weathering on that little workshop in the last photo looks realistic, it wouldn't be sir John's domain by any chance?


Thread: 3 ph motor conversion to VFD, any issues?
13/07/2014 09:46:35

Hi Everyone

Thanks for the fascinating and helpful information, it opens up some interesting options, and I have learnt a great deal form your responses.

I took the motor apart but I could not confidently identify what internal wires to change to convert it to Delta, I will ask a motor rewind company what it will cost for them to do the job.

I don't have any preference as to whether or not to keep the existing switch gear or do the extra work of changing it to suit a new set up. The main aim is to get the machine running using as much of what I already have as possible, hence the desire to use the existing motor. In this respect Stuart's information concerning the base frequency set to 29Hz is very attractive.

However, a new development. I have been given an Inverter and motor, the motor is 1.1 kW dual voltage and the inverter in 230v 3ph output. Using this will involve boring out the pulley and putting in a new keyway and adding the control switches etc.

At the moment my preference is to use the existing motor and either follow Stuarts suggestion or have it changed to delta configuration, I can use the gifted inverter for this. The gifted motor would however give more power though for my use I don't really see the need, I still have the belt change to use when higher torque is needed.

Any further suggestion very welcome.

Thanks again to everyone.


11/07/2014 15:15:37

Hi Everyone

I bought an Elliott Victoria horizontal mill advertised on this forum, lovely machine.

It has a 1 hp 3 ph 440v only motor (not dual voltage), I only have domestic single phase.

The wire connections are buried in the motor winding, I assume that a motor rewind company could convert it to delta connection?

My question is; if this motor is converted to delta would there be any issues running it from a 3ph 220v output Variable frequency drive? or would I be better off using a dual voltage rated motor.

Appreciate any recommendation form though with electrical knowledge.



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