Member postings for Paul Lousick

Lots of wood carving disks for angle grinders are available on ebay which are made for jobs like that.

But use with caution as they are very dangerous

My Ruston Proctor traction engine from LSM came with a steam operated Moore Pump which I stopped building because I realized that it would not work. (also reported by other builders). It is a single cylinder pump with a slide valve, directly coupled to the piston rod.

Slide valves on engines work OK because the inertia in the flywheel carries the valve past the mid point where both steam ports are closed but on a slow moving pump the valve can stop moving, covering both supply ports.

Duplex pumps like a Worthington have 2 cylinders in which the piston on the RH side operated the slide valve on the LH side and when it has finished its stroke the opposite happens. A hydraulically operated shuttle valve is a similar design.

I am in the process of adding a shuttle/change over valve to the pump which I already have.

Not an elegant look but deforming the hole with a series of small dimples around the hole with a centre punch will tighten the fit with the screw. (OK for lightly loaded applications)

Hi Sebastian, More information, photo of what you are making would help with a suitable solution to your problem. (some holes that I have drilled/tapped oversize or out of position have been remedied by silver soldering, filling with JB Weld or making an oversize screw to suit the hole)

DK, Do they make M2.5 helicoils ?

Sarik Hobbies sell plans for a J L Austin-Walton twin cylinder, double acting steam pump for £13.00

**LINK**

Hi John,

They are 3D CAD files and you need suitable software to open the models, then you can create drawings.

Castings and drawings are available from Stuart Models https://www.stuartmodels.com/product/steam-boiler-feed-pump-unmachined/

Edited By Paul Lousick on 02/11/2022 09:16:52

There are models of steam operated boiler feed pumps on Grabcad.com and are free to download.

Worthington Steam Pump - Utilizing a slide valve, directly linked to the pump piston. Files are in STEP format and can be imported into most 3D CAD packages.

Youtube video **LINK**

**LINK**

Or a Stuart Boiler Feed Pump which has a hydraulic shuttle valve, a more reliable way of reversing the pump direction. Files are in Solidworks, STEP and Stl format.

**LINK**

This is a link to Edward T Westbury's post about the Muncaster engines which were in Model Engineer.

The 2 cylinder is listed but does does not contain the complete article which was in a later issue of ME. Does anyone have a copy ?

**LINK**

Hi pgk, The CAD model is fully constrained and pivots as it would in a real model.

Michael, It is a different type of mechanism and also simpler than the one I put in the link above. No sliding surfaces are used to guide the piston rod, just linkage arms. (not as good as trunk guides as used on other engines)

The flywheel in the 3D model can be rotated and set at any angle (shown below at 0, 90 and 180 deg,) which moves all of the associated parts which can be dimensioned in a 2D drawing.

I tried raising the vertical link slightly to see if this improved the offset at the top pivot but was not successful. Now will try varying the lengths of the other arms to see what happens.

Edited By Paul Lousick on 26/10/2022 10:38:42

After a bit of searching on the net, I am a little wiser. The Watts linkage and Peaucelliar -Lipkin linkage has 6 levers to accurately aligns and supports the piston rod with the cylinder axis. **LINK**

The Muncaster engine has a simpler system, although not perfect, should work for my model engine. This is the result of my investigation so far. I have plotted the offset of the linkage arms in relation the axis of the cylinder and found that the slot in the left arm only needs to be 0.5mm long to compensate for the difference in length as the arms rotate.

When the piston rod is fully down , the rod end is guided by the cylinder bush and cannot move sideways. The length D=26.5mm. When the crank is at 90 degrees, D=27.0mm. At 180 degrees D=26.5mm but the rod end can move to the left because of the 0.5mm slot in linkage arm .

My thoughts are that If I lengthen the vertical (113mm) link on the left side slightly, I can get plus/minus 0.25mm offset at the top position.

Thank you gentlemen for the reference data. You have given me something to play with and do as suggested and plot the linkage motion.

Paul

What is an EX_ file?

Thanks Jason

I have just installed Windows 10 on an old computer and did so with a Local Account (button on the bottom left hand corner). Also said No to Cortana and other online options.

Change to a Local Account by:

1. Save all your work.
2. In Start , select Settings > Accounts > Your info.
3. Select Sign in with a local account instead.
4. Type the user name, password, and password hint for your new account. The user name must be different than any others on the device. Note: If you’re using Windows 10, version 1803, you can add security questions—instead of a hint—to your local account to help you reset your password in case you forget it. Check your version of Windows 10
5. Select Next,then select Sign out and finish. Sign back in with your new local account.
6. If you didn’t add security questions to help you reset your password, it’s a good idea to create a password reset disk. If you don't do this and then forget your password, you won't be able to recover it.

(Yes, the front arms in the detail views have been removed to see the slot in the rear arms)

I understand that each pivot arm describes an arc and assumed (should never do that) that both arms working together would cancel out the problem. If the slot is required, the rod will not be guided properly and will wobble as it moves. Not an ideal design but they look good when they move.

The linkage arms on the Muncaster engine below are supposed to keep the piston rod aligned with the axis of the cylinder but the left arm (one with a middle pivot point) has a slotted hole instead of a round hole, allowing the arm on the right to float in the slot.

This does not keep the piston rod aligned exactly with the cylinder axis because of the slop. Is this normal with this type of guide-linkage ?

Does anyone have geometric design data of how these linkages are supposed to work?

Have another cast at a foundry. Make a simple pattern out of wood that is slightly bigger than the 18" x 6" x 1" thick shape. Tell the foundry that it is for a museum and not needed immediately and they may make it for the cost of material when they are pouring something else.

Smaller OD flat washers, suitable for cap screws, etc are commercially available but you will have to go to a special nut and bolt supplier. They will not be available at the local hardware store.

Car accessory shops sell high temp paint in spray cans for painting brake calipers and good for 250 deg C.(limited colours). Paint for exhaust manifolds, 650 deg C. (only available in black, which I used on my traction engine chimney)

Some good reading about gauges for screw threads.

One of my previous jobs was working for Borg Warner (American automotive supplier) in Australia, designing gauges in in one of their gearbox manufacturing plants. Gauges were use on their production lines and in their metrology labs. Learnt a lot about tolerances and the accumulation of errors when dimensioning a drawing. Gauges for measuring shafts, etc to ± 1/1000" tolerance had to be made ± 2/10000".