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Member postings for JasonB

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

Thread: 4 stroking a Merco 61...
15/08/2019 06:56:36

Yes.

14/08/2019 20:42:46

Sorry, I've only ever turned my liners from Cast Iron or steel barstock and either lapped in the piston or used rings.

Edited By JasonB on 14/08/2019 20:47:08

Thread: lathe part supplier asking questions over my head...help
14/08/2019 20:15:19

I would imagine that most radii shown on clocks which seems to be your intended use would be more for decorative purposes and more often that not would be turned freehand with a graver than using a form tool so "look " is more important than absolute accuracy.

Even grinding to a printed template that can be stuck to the tool or cut out and used to mark the tool will do, this picture shows a tool in th emaking, with a hole drilled as I mentioned above to form the half round then the printed template has been used to mark th erest of the shape.

The completed tool in use

And completed part

And a bit of big boy 5" dia hand graving

Thread: Can Anyone Help Me to Identify This Very Old Boiler Please?
14/08/2019 19:46:37

Could be built along the lines of a Merryweather boiler where you would not see the tubeplate as it is a smaller diameter than the boiler shell. Plenty of cross tube boilers about where you only have a ring of rivits top and bottom sucjh as this

Edited By JasonB on 14/08/2019 19:52:10

Thread: Commercial boiler identification marking
14/08/2019 19:32:35

Not forgetting the all important CE marking if that applies. and test pressure

WSME in the case of Western Steam

Edited By JasonB on 14/08/2019 19:33:45

Edited By JasonB on 14/08/2019 19:34:10

Thread: 4 stroking a Merco 61...
14/08/2019 14:04:42

belt drive would be very simple at the bottom end as you just need to replace the gear I showed with a toothed pulley, don't even really have to cover it up if you use a sealed bearing or two. The backplate could then be made the same overall shape as the original which would look neater. Then just a pulley with twice the number of teeth on the camshaft(s) or rotary valve(s). Check your PMs.

Thread: Where do I buy these, I've looked every where.
14/08/2019 13:07:07

No, best to gauge the diameter of the hole in the motor with a drill bit shank

Thread: 4 stroking a Merco 61...
14/08/2019 13:03:15

I think the special had the linx in it which is the belt drive OHC, but if going for pushrods then the Bobcat/jaguar head would suit

Thread: Where do I buy these, I've looked every where.
14/08/2019 12:58:52

just type "flip top oiler" into your favorite search engine or e-bay

Thread: 4 stroking a Merco 61...
14/08/2019 12:34:16

Yes it was just a generic plate that would be more of a block with hollowed out areas for the gears.

Have you gone off the belt idea as the shaft that the larger gear runs on would easily take a toothed belt.

The gear scan be placed back far enough so that they don't have to fit the Merco crankcase but ideally you would not want the enclosure to be much larger than the width across the case.

If you are going for gears, cam and pushrods then have a look at the head for the Nemett "Bobcat" which is quite simple to make

Thread: Part built Allchin 1.5 inch
14/08/2019 11:40:33

Just bear in mind that under steam the boiler will elongate a bit but the piston rod and motion won't so cold settings of piston and valve will need tweaking when hot.

Thread: lathe part supplier asking questions over my head...help
14/08/2019 11:38:21

You don't need to buy one, for a concave gauge just drill a hole twice the radius you want in something thin and then cut/file away the waste until you have a 1/4 circle left to use as a gauge.

For a convex gauge just use a drill who's diameter is twice the radius and offer that upto your tool.

If you are wanting to round over a corner or add a concave mounlding to a corner then it is also possible to hold a round over milling or router cutter or in the toolpost and use one of the flutes to cut with.

For tools with a concave cutting edge you can also just drill a hole in some gauge plate and then saw/file away half to form a bead or 3/4 to form a round over cutter and then harden.

Thread: 4 stroking a Merco 61...
14/08/2019 11:20:34

The bearing I show would fit in the backplate not the crankcase.

As you have a deep recess in the back of the crankcase the bearing(s) can sit in a spigot turned onto the front face of the backplate, this would then also move the disc further in towards the crank pin so you can then locate the drive easily.

stebro backplate.jpg

So the backplate would look something like this on the side that fixes to the crankcase with spigot to fit the case and a recess for a bearing and through hole.

 

Edited By JasonB on 14/08/2019 11:21:21

14/08/2019 10:44:44

I would imagine that the pinion is mounted onto a shaft with integral disc and some form of bearing is trapped between gear and the back of the disc. To reach far enough inside the hole in the disc could be extended out from the surface of the disc., may want to add a small counter balance to the disc to compensate for the extension.Sketch shows two discs so the extended hole can be seen and how they may go together. Think I would be tempted to but a bearing on both sides of the pinion either ball or bronze.

stebro drive.jpg

14/08/2019 09:53:04

This Jan Ridders engine gives an idea of how the rotary valve works, ideally the valve would be placed in the head more like this. Probably offset the cam to one side of the head and have the inlet and exhaust on opposite sides then you would have room for the spark plug. Or keeping to the twin cam theme you could have twin rotary valves which may make sealing easier

Edited By JasonB on 14/08/2019 09:54:50

14/08/2019 09:38:49
Posted by Niels Abildgaard on 14/08/2019 09:26:18:

Why not try a worlds first:

How do you get a 4 cycle from that with the cam being on the crankshaft?

Stripped down Stebro here which seems to show a smaller pin in the crankpin but the gear block is the wrong way round to see if there is a mating disc on the pinion.

Edited By JasonB on 14/08/2019 09:42:02

14/08/2019 08:14:47
Posted by Barrie Lever on 14/08/2019 08:02:44:

The rotary valve layout might save on making a crankshaft as well, I think it might be possible to pick up drive for the belt from the crankpin by getting a hole into the pin and pressing a drive peg into the hole.

Yes, that is what I was thinking to drive it off the crank pin, if there was any spare length on the pin then a socket to fit over it would save having to drill the pin. I'm assuming the pin was part of the crank rather than a separate pin inserted into the web which would have made it easy to just fit a longer pin.

Looking on the web it seems that there was a commercial conversion made by a company called Stebro but that used the traditional push rod arrangement. Would be worth searching to see how that drove the gears and cam.

Thread: Slitting Saw - which one?
14/08/2019 07:38:18

You could actually do it with a 63mm saw on a 1" OD arbor and still be able to get your stress relief holes in if you cut each slot individually feeding along the bolts length.

bolt slot.jpg

Thread: 4 stroking a Merco 61...
14/08/2019 07:01:34

I don't see why the small amount of milling could not be done on a lathe with the use of a vertical slide.

Barrie's suggestion of a rotary valve would save on making the cams but you are still going to meed to make a new back plate and head in either case. Just the cams that you would save on.

13/08/2019 20:16:53

Nemett Lynx would be a good one to take details from though for a conversion you would probably want to put the belt at the back of the engine.

Twin cam 4-valve something like a HEMO would look good but I've not seen drawings for that.

Edited By JasonB on 13/08/2019 20:34:04

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