Member postings for Brian John

Aha...so that is why a jig IS needed ! I have made the rims of the eccentric too thick at 2mm ; the rims should only be 1mm thick giving an overall thickness to the eccentric of 6mm. If the rims are 1mm thick then it could not be held in the lathe chuck for cleaning up the end which has been parted off. It was a major brain fade on my part. I have put the figures for the jig into the original formula (3mm offset and 30mm round bar) and I get the same 4.4mm packing result. So I can complete the jig using the same packing.

Does this look safe for using the boring bar ? The disc is 3.5mm thick. Or should I bore another hole in some fresh 30mm brass and then part off ?

I realise that I could bore the 18mm hole in the centre of a disc for the purpose of shaving a bit off the rims. The 18mm hole does not need to be offset for this but I have already drilled it out to 9mm so I thought I may as well use it.

Edited By Brian John on 27/09/2016 13:40:43

I am not sure how to calculate E because I do not know what the valve travel is. So using the first formula and requiring 4.4mm packing I found a brass disc in my scrap box which was 4.8mm. I mounted this in the lathe and reduced it to the required thickness of 4.4mm. The work piece was marked with a black dot (3mm off centre) and when mounted with the packing it was correct. I checked it with the dead centre then started with the centre drill. All looked good so I bored about 1/4 of the way through with a 4mm drill bit then all the way through with a 5mm drill bit. (I am making two eccentrics, one at each end of the work piece). I then used 5.8mm and a 6H7 reamer to finish the hole.

The edge of the bored holes are 4mm from the edge of the work piece so this correct : 2X(4+6)=20mm. I parted off and then cleaned up the ends by taking facing cuts. By carefully mounting the eccentrics in the chuck I was able to use a small file to chamfer the edges. The eccentrics were then drilled and tapped for M3 grub screws. The outer races are a perfect fit so everything looks good.

I was going to try the other method and make two more eccentrics as outlined in the instruction manual using the jig but my drill press will not drill anything larger than 9mm : the drill chuck comes off ! It would have been nice to see if that method works but the packing method seems much simpler.

Edited By Brian John on 27/09/2016 08:00:37

Edited By Brian John on 27/09/2016 08:03:50

Edited By Brian John on 27/09/2016 08:07:47

Neil : I have not cut the eccentrics off the bar yet.

If this works I may be able to hold the steam chest in the circular jig I used for facing the ends and do something similar for the 6H7 bore in that. The ''bar diameter'' in the above formula will have to be modified.

Journeyman : thank you for the formula. I know I had seen it before somewhere but it did not mean much to me at the time.

By my calculations, the packing should be 4.4mm thick.

Hopper : I had forgotten about the faceplate. That is another option I can try.

Edited By Brian John on 26/09/2016 11:25:56

I thought it could be done using a three jaw chuck but when I used a 3mm thick piece of packing it was all wrong. But as you have pointed out, if the hole is 3mm off centre then that does not mean the packing should be 3mm thick. I will experiment further tomorrow as per your suggestions.

What puzzles me is why the instructions did not mention this packing method rather than the more complicated jig method. I suppose the jig would make it easier to put a chamfer on both sides but that is hardly necessary.

Edited By Brian John on 26/09/2016 10:39:28

Okay, I will leave that piece for now. But I may need a 4 jaw chuck to make some of the other pieces. I started making the eccentric today using the flat edge of my parting tool. I kept shaving a small amount off my moving the tool from right to left until I got a good fit with the outer race as per photo #2. Now the instructions say to bore the 6H7 hole using a jig which I proceeded to make but how am I to bore the 18mm hole in the jig ? I have cut the 30mm X 3.9mm disc as per the instructions. Should this now be mounted horizontally in a vice and the 18mm hole drilled with the drill press ? I do have a set of large drill bits (12-24mm) of doubtful quality.

If I had a four jaw chuck I could mount the eccentric work piece from photo #2 off-centre with a 3mm ''chock'' then bore the 6H7 hole that way. Is that how it is done ? I think the 6H7 hole could also be bored in the steam chest using the same method.

Edited By Brian John on 26/09/2016 08:25:10

Edited By Brian John on 26/09/2016 08:26:24

Edited By Brian John on 26/09/2016 08:30:22

I have made two cylinders and started the cylinder covers. I was going to turn the other 15mm ends of the cylinder covers to fit the cylinders when I remembered that after I mill the flat on the cylinder then I have to bore two 2.5mm holes into the cylinder walls so this will ruin the smooth finish I have put on the bore. Is there some way to clean up the two holes on the inside of the cylinder without damaging the bore ? Or will I have to take a cleaning pass (0.1mm) with the boring bar and then repolish the cylinder bore ?

NOTE : I am thinking of buying a 4 jaw chuck to mill the cylinder. Machinery House have one left in stock but I am not sure if it will take the 34mm cylinder end on ; it might be at its limit doing that so I will ask first. The first photo below shows the wooden mandrel I made for polishing the cylinder bores with 800 and 1500 grit.

Edited By Brian John on 25/09/2016 05:26:09

I buy my brass new ; the scrap yard brass is not much cheaper and it is often work hardened.

I buy my aluminium from the offcut and waste bin section of an aluminium workshop (they make trailers etc.)

I buy my copper pipe for boilers from the scrap yard as it is MUCH cheaper than buying from the plumbing supply shops. They also have many bits and pieces you cannot buy such as 60mm diameter copper pipe which I use for fireboxes. I am lucky to have a scrap yard that will let me wander in and look around. Most places will not let you do that now due to safety reasons.

I completed two plunger joints (part 14) today using a jig I made from 8mm hex brass. I was able to hold the work piece in the tool post while I used the slitting saw to cut a slot and the jig was also used when drilling and tapping the cross hole. I did try to make the M3 thread using a die but the die is stuffed : I had forgotten to order a new one. So I just cut the end off the piece then drilled and tapped for M3. I did not have any M3 threaded brass (it is on a slow boat from China) so I cut the thread off a stainless steel M3 socket cap and then fixed it in position with high strength Loctite 263. It seems to have worked out okay. I made the minor shaft all 5mm in diameter rather than 4mm and 5mm as per the plans as this was easier to hold in the hex jig. The jig has two M3 grub screws on either side to grip the work piece. I think 10mm brass hex would have been better to give more thread for the grub screws.

Edited By Brian John on 20/09/2016 08:36:57

More smaller parts completed : the connecting rod bearing(13), the bearing cover(12) and the eccentric outer race (19).

I just realised that I have spent so much time thinking about the flat side of the cylinder that I have not given much thought to the cylinder itself. If I bore the 15mm hole first then that might make it difficult to turn the inner diameter of 24mm because I cannot support it between centres. But if I turn the inner and outer diameters(24mm and 26mm) first while supporting between centres than that will make it difficult to hold the piece securely in the chuck when I bore it later. How should this be done ?

Edited By Brian John on 17/09/2016 11:50:00

This steam engine will be mounted on a base together with a boiler to form a steam plant. I finished silver soldering the boiler today : the main boiler section is made from 65mm diameter X 70mm long copper pipe. All this was salvaged from the scrap yard. I experimented with some silver solder purchased from the plumbers supply shop but although it is cheaper, I will not be using it again. The silver solder I buy from the Miniature Steam is far superior : it melts and flows very well.

I still have to apply the insulation and the wooden lagging made from mahogany strips. I use a standard Mamod safety valve as the filler plug.

Edited By Brian John on 16/09/2016 11:39:08

Would this 19mm fly cutter be suitable to do the cylinder ?

**LINK**

I have made the jig for the steam chest and it has worked well : the square brass has been faced off and shortened to 30mm ready for drilling and tapping. I probably overdid it with three M3 socket caps....two probably would have been enough.

Can I use this jig somehow to drill the 6H7 hole for the control valve like drilling a hole for an eccentric ? The centre of the hole is 6mm from the side so that makes it 2mm off centre. I think I need a 4 jaw chuck for that. The diagrams are on page one of this thread. I may have to drill it in the drill press, lining up one side with the drill bit to ensure the hole is parallel with that side.

Edited By Brian John on 14/09/2016 08:07:23

Edited By Brian John on 14/09/2016 08:09:40

Edited By Brian John on 14/09/2016 08:10:54

Edited By Brian John on 14/09/2016 08:12:39

Did you drill the crank plates while they were clamped together ?

Edited By Brian John on 13/09/2016 11:24:58

Okay, I can now see how that would work. I will have to order a fly cutter and make up the cylinder.

Today I made up two of the joint parts (20). This connects the control valve to the eccentric outer race. The plans call for the M2 thread to be cut on the spigot (?) with a die but I have found it much easier to leave off the spigot then drill and tap for an M2 threaded rod. The threaded rod is held in place with Loctite. This gives a neater finish with the parts sitting flush when screwed together.

Edited By Brian John on 13/09/2016 10:25:32

The Beng's steam engine and flame eater kits specifically mention NOT to silver solder due to problems with distortion. They advise soft soldering only for the crank shafts. I thought it would be okay to silver solder but I will have to try it some time to see what really does happen !

I was initially reluctant to make something if a vertical slide could be bought off the shelf but due to the lack of availability it looks like I may have to go the ''home-made'' route. I am thinking about it while I make up all the other parts.

John : the Toolmaster L276 is metric and it will fit my lathe exactly but there are none to be found anywhere.

In the meantime : the steam chest is 16mm square X 30mm long. The supplied brass is about 32mm long so the ends will have to be faced off. I do not have a four jaw chuck so I intend to make a jig using some 30mm diameter X 24mm round brass I had in my scrap box. I will drill/bore the hole (about 22.6mm diameter) in the cylinder take the square brass and then drill and tap the cylinder for three M3 grub screws to hold it in place. I should then be able to face off the ends.

Is there another/better way to do it ?

Edited By Brian John on 12/09/2016 10:00:44

I am making as many parts as I can while I decide what to do about the lack of a vertical slide. Today I made the pulley (part 26) ; I actually made three of them. I did not have a 45 degree pointed tool to make the cuts as the per the diagram so I used the flat edge of a parting tool to shape the grooves then rounded off the edges with a round file held against the opening of the grooves while the pulley was spinning in the chuck. The grooves are 1.2mm deep so I am hoping that is enough to keep any pulleys in place.

What would such a 45 degree tool look like....I do not have anything in my kit box that would do it ?

Edited By Brian John on 11/09/2016 14:35:51

Thank you : no flux it is then.

John : here is the Toolmaster L276 slide. It is metric.

**LINK**

1. After numerous phone calls to many companies I have realised that I am not going to buy the Toolmaster L276 milling slide in Australia until they get a new shipment which is expected in November. Going on past experience that will mean it arrives in January next year...maybe ! Do they sell Hafco lathes in the UK ? Somebody might have the Toolmaster slide there ?

2. The steam chest is soldered to the cylinder using solder paste which I have never used before. Is flux required for solder paste and, if so, is it special flux ? I am getting different answers using Google search on the internet. I know solder paste is a mix of flux and solder but that does not mean that the metal to be soldered should not be pre-fluxed first.

Edited By Brian John on 10/09/2016 10:50:41