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Member postings for Brian John

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

Thread: Engine is binding for some reason : 7BIM engine by PM Research.
08/09/2014 09:51:48

UPDATE : The piston and the rod are still turning hence everything is getting out of synch. I will have to tighten the locking nut on the piston rod against the cross head to stop this happening. I did have it tightened at the other end of the thread to make it easier to adjust the length of the piston rod. (Two nuts and a slightly longer thread would be more useful here.) I am surprised that there is so much movement. The single cylinder 3BIM does not have this problem.

Try again tomorrow !

08/09/2014 06:49:38

I am still having problems with the RH cylinder : it runs for about 10 minutes then gets slower and slower and stops. Yet both the left and right side have been set up the same in terms of valve and piston settings. I am really puzzled at this.

Edited By Brian John on 08/09/2014 06:50:39

Thread: How accurate is bar stock ? Should you order a larger diameter ?
06/09/2014 17:56:03

If the drawings of a steam engine called for a 1/2 inch stainless steel piston would you order 1/2 inch bar stock or 9/16 inch and turn it down ?

Edited By Brian John on 06/09/2014 17:56:29

Thread: Engine is binding for some reason : 7BIM engine by PM Research.
06/09/2014 05:28:52

UPDATE : using Loctite on the piston nut did not help but it does not hurt either. Now I will not have to worry about this nut coming loose. I found that the binding only occurred under pressure and when I disconnected the air hose and turn the flywheel by hand the engine gradually loosened up. This indicated a problem with my valve settings. I found that the valve on the RH cylinder was not centred so I unscrewed it from the eccentric one full turn and this seems to have solved the major problem.

1. The RH cylinder is still giving a few problems : it requires about twice as much pressure (about 5 PSI) as the LH cylinder and even then it runs much slower. There is also a knock which I cannot locate. Any suggestions there ?

2. I also removed the gland packing as a possible source of friction and I have found that it makes no difference to the running of the engine. What is the point of it ?


Edited By Brian John on 06/09/2014 05:29:51

Edited By Brian John on 06/09/2014 05:31:28

04/09/2014 05:20:59

I have turned the crossheads over and it did not work ; the engine is still binding. I think the only thing left to try is the Loctite on the piston nut.

NOTE : I think I could disassemble and assemble this engine in the dark now !

Edited By Brian John on 04/09/2014 05:21:59

03/09/2014 18:10:38

1. The cylinders are brass and the pistons are stainless steel. Nothing is running long enough to get hot ; the different expansion rates will not be the problem. The 3BIM engine runs well.

2. The crossheads move freely without the pistons attached.

3. I will try flipping the crossheads over tomorrow but as these are probably machined in bulk I do not think they will be out of alignment. At this stage I will try anything !

4. I will disconnect one piston/cylinder and just concentrate on getting the other side to run without any problems.

Edited By Brian John on 03/09/2014 18:11:24

03/09/2014 14:24:26

No, it is mechanical binding. When I release the nuts at either end of the piston rods then things start moving again. I do not understand this at all. There is enough lubrication.

I might try loosening the piston rod nuts and holding them in place with Loctite and see how this goes ie. I will not tighten the nuts against the crosshead and the piston. I will leave some play there.

NOTE : these piston rod nuts control the stroke of the piston. It is how the piston is centred in the cylinder.


Edited By Brian John on 03/09/2014 14:29:22

01/09/2014 12:28:46

I am building the 7BIM double piston engine by PM Research. The two cylinders are not yet connected with a manifold ; I am running each cylinder on air to test them. I can get them running nicely for about 15 minutes but then they start binding up...usually at BDC.


I think the clue lies in step 4 of the instructions :

''Adjust piston rods in crossheads until piston strokes are centred in cylinders. Torque screws evenly to prevent pistons from binding.''

How does the reciprocating motion of the piston cause a torsional force ? If I can understand what is happening then I can work out a way to prevent it.

NOTE : I have already built the single cylinder 3BIM but this must have been a fluke as it runs perfectly !

Thread: Who makes Steam pressure gauges reading up to 20 or 30 PSI ?
31/08/2014 06:42:56

I have located a couple of 0-30 steam pressure gauges second hand but I am not sure what fitting is on them yet. How would I test them for safety and accuracy ?

Edited By Brian John on 31/08/2014 06:43:12

Thread: How do I tell stainless steel from silver steel ?
29/08/2014 13:11:07

Thank you, the silver steel is magnetic. The stainless is not. They are all slightly different lengths so nothing to go on there.

29/08/2014 10:52:38

I ordered a number of pieces of 6.35 mm round bar stock in both stainless steel and silver steel which arrived today. Nothing is labelled so how do I tell the difference between the two materials ? I cannot discern any visible difference between them ; it all looks the same to me.

Thread: Damaged Sieg C0 lathe...what to do ?
27/08/2014 06:42:08

UPDATE : Sieg have advised the supplier that it is not really safe to fix this myself so we are going to do a full refund. This is the sensible solution but it does leave me without a lathe.

Has anybody used one of these : the Nano ?


It looks rather limited in what it can do but I am running out of choices here.

Thread: Building the twin cylinder 7BIM engine.
25/08/2014 22:36:48

Thank you ; that will be very useful in helping me to finish the pipe work. So no hard soldering is required anywhere ?


Edited By Brian John on 25/08/2014 22:37:57

25/08/2014 09:56:10

A. I have the tee and the elbow. I also have a union but I am not sure if it is the correct part.


B. I think I should have bought more of these unions. Does anybody sell them in the UK ?

C. Why use copper at all ? It is much harder to cut a thread on copper than it is on brass although I might have more success now that I have purchased HSS dies.

25/08/2014 06:20:18

I have almost finished building the PM Research 7BIM twin cylinder engine. I just need to tweak the valve timing a bit then add the steam tubing which joins the two cylinders (the ''manifold'' on the plans).

1. Does this tubing have to be copper as per the plans ? It would be much easier the cut a thread on some brass tubing and join the cylinders that way.

2. I have to use some sort of union to do this. I have never done this before so does anybody have some diagrams or photos to show the process. Which parts will have to be hard soldered as I only have a vague idea how I am going to do this ?

3. Where would I eventually put the displacement lubricator ?

Thread: Damaged Sieg C0 lathe...what to do ?
23/08/2014 13:08:29

This damage has happened twice. I think it is very likely that it would happen a third time. Also there are very few places selling the Sieg C0I could and their prices are much higher.

I suppose I could buy one of these :

Edited By Brian John on 23/08/2014 14:22:34

23/08/2014 10:53:33

I agree, which is why I am not mentioning any names nor am I quoting consumer law to anybody. The supplier has been very reasonable and offered a full refund. I think I will accept this offer on Monday. However, that leaves me without a lathe. I have already ordered over $100 worth of bar stock which is currently in transit !

I could keep the lathe and wait until December until the spare parts arrive to fix it but I am not keen on poking around all that electrical wiring.

NOTE : I think that there is a small design fault with the lathe in that the base has an inverted U shape. Some sort of bracket or bracing needs to be installed at the factory to stop it ''spreading out'' if it ever suffers an impact.

Edited By Brian John on 23/08/2014 10:57:13

21/08/2014 06:08:52

A full refund has now been offered or I can choose to fix it myself when the parts become available. If I do ask for a full refund then what would I buy to replace it ? Nobody else seems to make a small lathe of this size and certainly not at this price.

I am also carefully examining the exploded diagram in the instruction book to see what is involved in replacing the two damaged parts : the base (#17) and the electrical fixed plate (#9).


Edited By Brian John on 21/08/2014 06:10:33

20/08/2014 18:18:27

1. So the electrical connections are just plug in types ? If that is the case then I could probably replace it myself.

2. The supplier is thousands of kilometres from me otherwise I would have picked it up myself in the first place.

3. Yes, the blow moulded polystyrene packing looks capable of dealing with any type of rough handling and I am surprised that the same sort of damage has been sustained twice.

4. I am reluctant to point the finger at the local couriers. Due to the distance that this parcel had to travel, it must have passed through quite a few hands before it got to me. It could have been anyone.


Edited By Brian John on 20/08/2014 18:25:15

20/08/2014 13:49:54

Yes, I agree that the whole base needs replacing.

They said if I send them the base then they will replace it in December when they receive a new shipment. So it would be December before I could get this lathe up and running. Wouldn't removing the base involve doing something with the electrical side of things ? It is this point I am not happy with. Actually, I am furious but I have avoided any further contact until I cool down a bit !

I do not want to mention any names at this point....perhaps not at all.

I might have to write this $500 off as money badly spent but who else makes small lathes like this other than Sieg ?

Edited By Brian John on 20/08/2014 14:01:12

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