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Tag: Making Gaskets

Gaskets with CNC, and progress on the Trevithick Dredger Engine.

Tomorrow I start silver brazing the 6″ vertical boiler.

But today I started machining the bronze end plate of the Trevithick Dredger Engine.

First I prepared a 100x25x200mm sacrificial aluminium block to hold the expensive bronze disks which will become the end plate and flange of the Trevithick boiler.


CNC drilling the 8mm thick bronze end plate and the sacrificial mounting block.


This thicker bronze disk (13mm thick) will become the flange which is brazed to the boiler shell.  The holes were also CNC drilled, then threaded using a battery drill, held vertically in my shop made threading jig.  The flange and the end plate require more holes and shoulders.  The mounting block will assist with repositioning.

Earlier I had called on GSMEE president Brendan, who happens to possess a CNC laser cutter.  I had discussed the possibility of CNC cutting some gaskets for the steam pump which will be made for the 6″ vertical boiler.  “No Problem”, said Brendan.


Taping the gasket material to the CNC laser cutter table.


Starting the cut.


The 15 gaskets accurately cut out.  Cut out by hand would have been a half day job.  The laser finished it in about 3 minutes, perfectly (plus maybe an hour drawing the pattern using a CAD program).  It is a 40 watt laser, and will cut through 3mm plywood.  No problem with this 0.4mm gasket material running the laser at 25% power.




Making Small Gaskets

My Bolton 12 Beam Engine is a steam engine, but to date, has run only on compressed air.

Compressed air, is invisible. Any leaks, might make some noise, and show up as a dirty oil leak, but are not visible to a casual observer.

In contrast, steam shows up every leak.

Our club is having its annual exhibition at The Geelong Show, in 2 weeks.  (See the post from 12 months ago about The Geelong Show)

Steam is available so I have decided to show my Bolton 12 beam engine, and to have it running on steam.

That has required making a steam connection and removing the compressed air connector, And more importantly, making every joint in the steam-air line,  steam proof.

So every join has been opened and a gasket inserted.  Some of the gaskets are oiled brown paper, and some are more permanent “liquid” gaskets.

Making the gaskets was a new and interesting experience, so I decided to make a photographic record.

I made the gaskets from brown paper.

I required 6 of these small gaskets, and 2 larger ones.


More components ready to have gaskets installed


Step 1. Make an impression of the surface in the paper using finger pressure.  Do not allow the paper to move.


Step 2.  Continuing to hold the paper securely, locate the bolt and steam holes using a pin.  


Step 3. Using an old centre drill, enlarge the pin holes. Rotate the centre drill anticlockwise to avoid tearing the paper. Push the the drill firmly while rotating it, and continue to hold the paper firmly against the surface.


Step 4. Use the fine scissors to remove the dags. A delicate touch is required.  Use the ordinary scissors to cut the outline.


It looks like it should do the job.


The reassembled beam engine.  The displacement oiler, and rope driving pulley have been added since the last photos were posted.

Amazingly,  after reassembly, I had no left over bits.  If it works on steam as planned, I will post a video.  Watch this space.

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