Member postings for JasonB

As nobody else has replied I would say add the drain cocks as it is easy to do at this stage as they can only help with getting rid of any condensate in the cold cylinders when you first start the engine. Or if you don't want to spend out on a pair of cocks you could drill and tap for them and just make up a couple of plugs then see how things go, if you get a condensate problem then just swap the plugs for drains.

The RSPCA have put a stop to that now

Along similar lines is to make an insulated box and then put a low wattage light bulb in the firebox which I have heard people use.

Like Andrew all my engines live inside, this chap had the right idea

Ron, if you wanted to try the alternative valve ports then give this a go. 4.0mm holes instead of 3.5mm and I have shown the X & Y positions which should make it easier setting them out rather than using the angled line and PCD that Julius has on his drawing.

Having repaired a Mamod traction engine for someone over the weekend I'm tempted to build one of these to the Original Muncaster sizes and see if I can add a reverse function along the lines of what the Mamod uses.

Gears look good John

I have machined a few more bits for the 4-stroke conversion of the RMC engine. rocker arm to operate the exhaust valve and a post to mount it on that is fixed to the head. I will bond this on with JBWeld and also fill the CSK screw holes and add some fillets to the internal corners so that the post looks like it was cast as one with the head. Both done on the KX3 and needing two setups each so that both sides could be machined.

And made a start on the epicyclic gearbox by cutting the eccentric on the CNC which did the profile with ease and also made light work of the doglegged end that lofts from a rectangle at the eccentric to a circle where the rod enters with just a light touch of a needle file required to blend the remaining too step overs. That is a 10-20-40 block not a 1-2-3 one!

No

You had he album set as private, I have changed it to public which should help. I had no problem adding an extra image when logged in as you.

Edited By JasonB on 26/01/2020 13:37:09

The other thing that you may have seen are very fine finishing cuts, if there are complicated angles and curves than the final passes will be done in very small stepovers to get the smoothest finish possible.

The current thinking is to use as much of the side of the cutter as possible with a shallow stepover and high speeds and feeds. This means the cutter wear is spread over all the cutter not just the end and the hot chips dissipate the heat.

These methods work best with heavy machines but just as suitable for hobby ones provided machines ability is taken into account, it is known as trichodial cutting. The program will work out where the tool move but the person setting up will have entered feeds, speeds, depth and height of cut to suit the material and cutter chosen though most manufacturers will publish guide figures or the CAm will have them already.

Are you sure the original is an eye bolt and not just a bent wire that was cast in probably with some sort of bend at the other end so it would not pull out.

The simple tubular saw suggested would be easy going in lead then just bend up some steel to match an remelt the lead you took out and pour into the hole to set the replacement hook.

Ron, may not be worth it on a single acting engine but I'll take a look at tehdrawings a bit later and see.

Fizzy, price is on their site at £1250, does not give a size but I doubt it is much bigger than mine.

Plus a photo of the one with the nail, if it is a cut nail with a hole drilled across it then you could spend a little time filing the exposed end to look like an eye same as these two that were made from flat bar.

Drill a pair of holes diametrically opposite and bend up a "U" shape from steel rod say 3mm dia to fit them

Next job was to shape that block of bronze in the previous photo into something a bit more shapely for which I used the CNC though it could also have been done on a manual mill but not as quickly.

This video shows the 4 separate operations. First is boring the hole for the central pivot boss , then the adaptive cuts which basically rough out the shape leaving 0.5mm to still come off both done with a 3-flute 6mm cutter followed by cleaning up the top rebate and cutting the central slot with a 4mm cutter and finally the finish contour with a 6mm ball nose cutter.

Still of the part after the first two operations

And this one is when CNC machining complete

A little bit of filing soon removed the facets left by the mill though if I had let it run longer I could have used a shallower stepdown but as it is to represent a casting the odd bit of handwork gives a better feel. I also made the two stiffening webs from offcuts of 5mm plate, 8mm for the top piece and turned a draft angle on the pivot boss. Here are all the parts before silver soldering.

Once cooled and pickled to clean it up the valve block was clocked level in the mill vice as there was no flat surface below to sit on parallels. You can also see that the solder I used to add on the extra bit of bronze had melted during the assembly soldering so just as well it was also screwed in place.

After skimming the port face back to final dimension the four ports were drilled and a central hole drilled and reamed right through for the pivot. Not obvious from the photos but I deviated on the traditional sizing of port and cylinder holes by making the port ones larger, this is supposed to help the cylinder fill and empty as the full area of the cylinder port is open earlier and closes later, more details on this web page

The ports were then extended down to where the inlet and exhaust fittings would be with long 3mm holes, the ends of these were later plugged with small bronze plugs loctited into place. Sorry for the fuzzy photo.

The two tapped holes for inlet and exhaust were added, M5 x0.5 for the inlet and M6 x 0.75 for the exhaust

Finally with the part held in a vice on top of the rotary table a 1mm deep recess was milled around the pivot which reduces friction and makes it easier for the cylinder to seat, also less surface to lap which makes the process go faster.

You run the exhaust from the engine back to fitting on th etop of the boiler and then it will go up the chimney to help with the draft.

Yes as Neil says just a thin mill scale, probably a bit of S275 steel. If I'm doing a lot of work on a part I will strip it off with brick cleaner(acid) first if not just leave it on as it adds a bit of texture which often siuts teh fabricated "castings" that I make.

You could cut it from a single piece of 35mm dia or use 32mm dia and solder the valve block to it or if you want to keep the swarf down then make with a soldered on top flange too then you only need 7/8" stock for the cylinder.

The original muncaster drawing shows the end cap soldered on which makes it easier to bore straight through, though loctite would do.

Can't see anything obvious on the drawings but as you say the hole must be there for a reason. Ask on MEM forum as there are a couple of members there who have built it.

One reason I suggested teh Unimat type is similar to what Clive says as they use a captive jacking screw rather than stepped packing blocks so a lot easier to work with on a vertical surface and easy enough to make from flat bar, in your case just use studs inplace of the tee bolts.

Also looks like you have totally exhauste dthe flux or did not use any as there is no sign of it on the workpiece. You will need HT5 or Tenacity No5, big burner, 4bar regulator and be prepared to wait for it to warm up.

Don't know what your blocks are made from but I doubt they are reflecting much if any heat back into the job. You also have the air holes of the burner down inside the blocks which will mean they don't draw in plenty of fresh air and may even cause the burner to go out.

Edited By JasonB on 25/01/2020 07:31:23