Has anybody built Beng's Danni Steam engine.

The first milled cylinder is on the previous page (8).

I seem to be limited to cuts of 0.25mm on my machine. What size cuts on brass could be taken on a decent size lathe, say a Sieg C3 ?

Edited By Brian John on 01/08/2017 14:20:57

We have discussed the use of solder paste before : to join the steam chest to the milled flat on the cylinder as per the instructions. What temperature solder paste should be used ? Most of the solder pastes on the market seem to be for electrical work so I think it would be unsuitable for engineering.

I am also thinking of fluxing both sides, put some 243 degree soft solder between the pieces like a ''solder sandwich'' then apply heat. The only problem might be stopping the top piece from sliding about once things become hot and fluid. 

NOTE : I did buy some solder paste from the US months ago but I lost it in the shift to the new house !

Edited By Brian John on 02/08/2017 01:31:28

If using separate flux and solder the correct way is to "tin" both surfaces and then "sweat them together"

Tin- flux the surface and then heat, apply a light coat of solder to the surface and while still hot wipe off any excess a natural fibre rag will do to wipe the solder off. Allow to cool

Sweat take the tow pieces, apply more flux to one and then place the two together and heat, you can add a little more solder feed in from the edge if needed when what was used to tin flows

I knew there was something else : there are two 2.5mm holes on the cylinder flat which mate up with two holes on the steam chest (24mm apart). I would think that these holes should not get blocked when soldering the two pieces together. The instructions mention nothing about this. What could be placed in the holes to be removed later in order to avoid these holes being clogged with solder : timber, aluminium wire, stainless steel wire ?

You could probable stick a match stick in the hole, it would also help to locate things while you solder as things can skid around a bit on molten solder.

Ian S C

A matchstick or some stainless steel ?: I have some 2.3mm stainless steel rod which fits nicely in the 2.5mm hole. I worry about timber igniting.

I finished the second cylinder today. Should the milled surface be touched up with a file or just leave it as is ?

I found that by drilling three 5mm X 2mm deep holes in the aluminium top plate that the screws on the mill slide could be more firmly located. This stops the cylinder pulling away from the vice. The two washers when held side by side measure 3.8mm so that gives me an idea when I am close to the required 4.0mm. There is no need to remove the work piece to measure it.

Edited By Brian John on 04/08/2017 10:14:02

Hi Brian, I'm yet to mill the three cylinders I'm working on (one for the single cylinder Bengs kit and two for the twin cylinder scratch-built version), but I too have been thinking about the posssibility of the inlet holes being blocked by solder and the need to adequately line up the holes. I too was thinking about using stainless steel pins to locate the steam chest against the inlets, but it might be a big ask to get the holes on the steam chest and the cylinder to line up absolutely exactly to fit metal pins. I am thinking that using matches might give a bit of leeway, even if it does start a nice wood fire when soldering, it might be possible to just blow out the ashes. I am still weighing up the options. Regards, Lawrie.

A question to anyone. The other thing I'm worried about is that initially drilling the steam chests I just used a ruler to mark the holes. That was before I figured out that using the graduated wheels on my Optimum mill/drill gave greater accuracy. As it stands then, some of the holes I initially drilled (now measured with a digital vernier caliper) are around 0.2mm to 0.3mm out of position - in relation to the valve slide or piston. My question to everyone is, how critical are these measurements - what tolerances should I allow. Should I remake the steam chests before I go anywhere near soldering anything to the cylinder? Regards, Lawrie.

Brian, will be fine to solder straight onto that milled surface. A bit of tipex correction fluid on any surfaces you don't want solder to take to will also help, at soft soldering temps a bit of charred wood won't do any harm.

Lawrie those slight deviations should not cause major issues.

Jason, Thank you. Sounds like good advice. I have been thinking that timing the engine within its inaccuracies will be what it will be all about in the process of getting it spinning. I think I'll just forge ahead. Regards, Lawrie.

It would depend on your method of heating, I would be using a large soldering iron, but you maybe using a torch, in which case the stainless wire might be better. My way, tin both surfaces, put in place and aline the holes, plonk the soldering iron on top, if a solder fillit does not form, apply a little extra solder to the edge, hold the top piece down with a screw driver and remove the soldering iron, then wait for the joint to cool down before letting go. The thinner the joint the stronger it is.

Ian S C

I have been thinking about the soldering of the steam chest to the cylinder while I complete the milling of the cylinders. The solder must fill the two inner holes on the side of the steam chest (the two outer holes will be plugged with timber or stainless steel to keep them open). The solder must also fill the two holes at each end of the steam chest. It all seems a bit ''iffy'' hoping that the solder is going to find its way into all the holes and do the job. Is there some way that the holes could be plugged PRIOR to soldering the steam chest to the cylinder ?

Edited By Brian John on 05/08/2017 09:47:04

The solder does not need to fill any of the holes.

You are basically sticking a flat (cylinder) surface to the area around the hole which will seal it just like if you put a bit of sticky tape over the hole.

Infact when you tin the surfaces you could keep the solder a couple of mm away from the holes which would help with reducing the risk of them filing with solder.

I thought people might be interested in photos of the bits for the single and twin cylinder versions of the engine, I have made so far. I had a bit of trouble getting the photos up, so I hope it works.

That is very nice work ; I really like the idea of a twin cylinder engine. How did you make your crankshafts ?

Hi Brian, The crankshafts aren't finished yet. I plan to screw them together with M2 x 5mm stainless steel grub screws. i drilled the holes 5.8mm and reamed them 6mm, holding them in alignment as I did it with short bits of silver street. It remains to be seen if I can retain the alignment in the process of drilling and tapping the holes for the grub screws (that I intend continuing a short distance into the silver steel rods) I'll let you know how I go. I may have to revert to solder, as specified in the Bends plans, but that looks like a fraught process to me.

The crankshafts are one of my few unfinished parts. I had trouble with these : I carefully drilled the holes in the crank arms but the shafts are not parallel. I had intended to do the same as you with the grub screws and I had already drilled and tapped the crank arms for that. I may yet try the solder method. I bought some more crank arms and these I will Loctite together before drilling them in the vice at the same time. Hopefully that will keep the shafts in alignment.

NOTE : I did not have this problem with the crankshaft of the flame eater engine.

Edited By Brian John on 06/08/2017 01:25:00

Hi Brian. Not sure if I am reading this right but you might be best to drill and tap the grub screw holes after drilling the main holes for the crank pins first. The reason being that the grub screw holes could cause your drill to wander and kick over at an angle when the drill tip meets the existing grub screw hole.

Definitely soldering or loctiting the two crank webs together will help keep things aligned better than just clamping both in the vice. Super glue can be used too. Destroy the bond with propane torch afterwards.

Edited By Hopper on 06/08/2017 05:15:27

Hopper : I think I did drill and tap after drilling the main holes (it was a while ago) but still ended up with things all askew. I was surprised because I had done exactly the same thing with the flame eater engine and I had no problems. Maybe that was beginners luck !

Yes, I will definitely use Loctite next time.

The cylinders are now milled and drilled and ready for soldering to the steam chests. I still cannot find that silver solder paste I ordered from the US. That would have been ideal for the job. I might move onto the crankshafts now and see how I go with my soft soldering skills before coming back to the cylinder/steam chest assembly.