Member postings for JasonB

Looks to be running smoothly enough so I would also say you may be at the limit of what your compressor can deliver, the volume is about 50% more than the oscillator that you did so will be a bit hungrier.

After turning the pivot bush it can be held in a collet block to firstly drill an dream the 3mm hole.

The collet block can then be repositioned so that the 1.5mm hole can be drilled at right angles to the first.

The size and shape of the adjusting nut is not critical and a diamond knurl will do if you don't have straight wheels. The pivot shaft is just a simple rod threaded at either end and hopefully you can find a spring of approx the right proportions to that shown.

The reversing lever is bent from 1.5mm rod and Loctited into the pivot bush.

The column can also be joined to the base at this stage with Loctite if you have a good fir or JBWeld if there is any movement. To endure the part face is at right angles to the bearing hole lay the two parts onto a flat surface when bonding and if you have a vice that opens far enough that can be used to holed them together while the adhesive dries. Once it has the cankshaft bearing can be loctited into place with 1mm protruding on the port face side and then the oil hole drilled through.

You should have something that looks like this if all has gone to plan.

You could try it without the O ring.

If your springs are a bit strong that won't help either as they will be taking engergy to compress, the inlet can be lighter than the exhaust.

With their workshop closed they probably have time on their hands to catch up on listing stock.

The pilot for counterbores often seems large but it is intended to ensure that the internal fillet where the head of the cap screw meets it's shank does not make contact with the edge of the hole therefore ensuring all the load goes to the underside of the head. If using other methods and small clearance holes use a small CSK bit etc to ease the edge.

You should not be able to feel any compression or air trying to push the piston until you are over TDC

Inlet valve should open just after TDC and close say 20 degrees before BDC.

Exhaust wants to open at or just after the inlet closes so open at 20deg before BDC and should remain open until the piston is back up at TDC

Is there any sign of the piston moving on the power stroke away from the head?

Have you plugged the holes on the outside of the cylinder?

Edited By JasonB on 01/04/2020 16:20:13

[b]Column Base[/b]

This is probably the most complex part of the model so take your time.

I chose to make mine from a slice cut off a piece of 50mm dia cast iron bar though it can just be squeezed out of 1 3/4" material if you have that to hand. Once the bar had been faced off both sides in the lathe to the required 11mm thickness it was transfered to the mill to form the basic 31 x 37mm rectangle.

Holding the block in the vice with what would be the port face upwards the work was centred in X and the bottom edge located so that the tree 2.5mm ports could be drilled to depth and then the hole for the pivot drilled and reamed 10mm. To save putting any holes in the wrong place I used a Sharpie to roughly indicate where the various features should be.

If you don't want to have the air supply come in from the side of the base then the work can be turned the other way up and a 3.5mm hole drilled to join the inlet port and then tapped M4 x 0.5. so that the air can come in from the back of the column.

Next the sides can be milled away to form the feet followed by drilling and tapping M5 x 0.5 either side for the exhausts.

To form the detent arc I chose to hold the job in my mill vice which was in turn mounted onto the rotary table but the Arc could just as easily be turned on the lathe and then the excess milled away. The Vee notches were cut using a spotting drill at 15degree intervals, again if not using a rotary table they could simply be filed with a needle file.

The two 3mm holes to mount the engine to the base, the 2.5mm air supply up to the inlet port and 5mm dia one for the column spigot are simple enough, filing buttons can be used to shape the two feet.

Edited By JasonB on 31/03/2020 14:24:18

Before going on with the build I'll explain a bit about the reverser as the parts for that are the next to be made.

As I mentioned I recently repaired a Mamod traction engine for someone and got the idea from the reverse lever fitted to them which is simply a pressed steel lever that rotates and has an eccentric hole for the cylinder pivot.

There are three ports on the base, a central one that is the inlet with the ones either side acting as exhausts. As the cylinders pivot point is moved from one side to the other it will use two of the three holes depending on what side of ctr it is.

So with the lever down the pivot moves towards the right when viewed from the back.

Looking at the front you can see that the cylinder will oscillate between the left exhaust and central inlet.

If the lever is now moved upwards so that the pivot is now on the opposite side

Which means that the cylinder is now oscillating between the right hand exhaust and central inlet, this has the effect of making the upward power stroke take place when the crank is on the other side of centre thus reversing the direction in which the flywheel rotates. An added bonus of this arrangement is that with the lever placed somewhere between these two extreams the amount of time that the ports are open for is altered so the reverser can also be used to control speed and or save air/steam.

Paul, i was talking about the Pocketmags app on my W10 machine where I can view all my subscription copies even off off line, there is not the 2 page print option that you get when online via their site so have to snip or screen print etc each page.

Couple of points to put right.

You can get access to paid for issues via Pocketmags even after your subscription has ended.

Magzter won't give you access to the digital archive here nor will subscribing directly to Pocketmags

NDIY, yes you can download the whole mags from Pocketmags and a snip of the screen is readable but slightly lower quality..

Ron has spotted an error on the drawing for the exhaust valve rod which was shown too short. Revised drawing now available here

I'd work it out from the drawings and then see how that compared to the casting and adjust if you need to.

You could use unslotted round head screws with the nuts inside, quite a common way to do it on traction engines

Thanks Rod, just don't expect a full write up and drawings at the same rate!

Actually I've probably spent more time with the Bonsai over the last couple of weeks than in the workshop as it's the time of year for repotting etc. have not really got myself motivated for a new build yet though there are a few casting sets sitting about and scratch builds that are 3D modelled, I did dig out my Hoglet that has been sitting around almost done for too long and have progressed that, just waiting for a couple of magnets to trip the ignition. How is your Farm Boy?

Probably better to add something to the page that comes up when you place an add if possible as a lot of people just use the classifieds and not the forum.

I think I would start by lightly filing the top end to give a flat surface for marking out on, swing 4 arcs of approx half the diameter in from points around the edge and then place a punch mark where the middle is likely to be much like whats shown in this image

Now holding the casting by the flange in the 4 jaw chuck get the bottom and top punch mark to run as true as possible then at a slow speed drill with a ctr drill. Bring up the tailstock for support and turn the top parallel section to 1 1/16" and lightly face the end as far in as you can reach without hitting the tailstock ctr.

Reverse the casting around and now gripping by the top parallel section ctr drill the bottom end and again bring up the tailstock ctr for support. Face the end and then the outside of the flange followed by the 31/32" collar. Then taper turn the outside.

Remove the tailstock and fit the fixed steady to run on the 31/32" diameter to support the casting while you drill it out to 3/4".

Reverse the work once more so you are holding by the OD of the flange and set the fixed steady to run on the 1 1/16" top section. You can now bore out the inside to the correct taper.

So with us all on lock down I thought it would be a good time to get a set of drawings together and write up the build if anyone wants a small project to pass the hours. This time rather than separate drawings I have put all 10 sheets into one pdf which should make it easier when looking over them on the computer as you can scroll up and down rather than having to open multiple files. I have also done a Bill of materials for those that like to have one, note that sizes are generally of the finished part so make your own allowances for holding, parting etc.

In most cases materials can be substituted as well as methods, anyone with queries please ask. Also if you find anything wrong or missing on the drawings please let me know and I will update as needed.

Column

Start by facing the end of your 15 or 16mm stock and then form the spigot on the end followed by a small ctr drilled hole. The material can then be pulled further out of the chuck and tailstock support used while the tapered section and decorative beads are turned.

Transfer the part to the mill and hold by the remaining bar in a collet block or indexer to mill the two flats at the top followed by drilling and reaming for the bearing.

With the work back in the lathe form the small boss for the oil hole before parting off. The oil hole can be drilled while lightly holding the top of the column in a collet or in the 4-jaw, you could even leave it until later and just use the bench drill.

Bearing

This is a straight forward turning job, the column can be used to gauge the outside diameter and the 5mm hole is best reamed. The bearing is Loctited into place with 1mm protruding on the cylinder side and then the oil hole drilled through but don't do either of these things yet.

Crankshaft

A very easy part to make from either Precision Ground Mild Steel or Silver Steel (Drill Rod) but leave it say 1.0mm over length for now.

Crankpin

Another simple part from Silver steel

Crank Web

Start by forming the 8mm dia boss on the end of a piece of 25mm dia steel then drill and ream 5mm. Part or saw off leaving the web 1mm over thickness.

Transfer to the mill, locate the ctr and then move 10mm to one side to drill for the crankpin.

To mill the tapered sides slip the crankshaft material into the 5mm hole letting it rest on the vice jaws and the 2.5mm drill into the pin's hole but raise this up 2.75, you can see the black 2.8mm drill shank I used for this and then mill one side before repeating for the other though there is not so much to hold this time around so light cuts after sawing off most of the waste.

After rounding the corners to the final profile with a file the web can be Loctited to the crankshaft with 638 or 648 and set aside to dry. Then holding the shaft preferably in a collet a couple of cuts can be taken across the end of the web & shaft to bring them both to final size. deburr and then Loctite the pin into place.

Drawings to download

Bill of materials to Download

Probably you had looked at it a few times or were watching and then e-bay sent a note to say it was no longer available but failed to work out that it was you who had bought it.

Looking good, you can also get a bit more of a "cast" look by knocking off all the external corners with a file or Dremel so they are a bit more rounded and not so regular.

Will get back to you tomorrow.