Borderer Cast iron scratch build

A little more done today

I made the lower cylinder covers and gland nuts , Cast iron and silver steel….

Went with 16mm registers as I’ll go with 16mm cylinders

Just looking into piston materials……

I haven’t got any stock but have a choice of any suitable material

Cast iron seems to make sense on cost
Gun metal maybe better for cylinder wear not sure , obv corrosion resistant

The ring material will be Viton

Hopefully ppl with more experience can chip in

If the o ring is doing the sealing, then the piston itself can be small enough diameter not to actually touch the walls of the cylinder (this is they way I build mine, not everyone does it that way), so wear is not an issue. The piston can then be the same material as the cylinder. If, however, they will touch, then you want a dissimaler metal to avoid galling and wear. Also, if you will be running on steam, then corrosion is also an issue as you point out, even with steam oil there will be moisture left in the cylinder after a run, so you don't want something that will rust easily.

Thanks for your input

I’ll go with Bronze/Gm for them , corrosion isn’t a great set up as you say !

I have now got reamers and drills to have a go at the bores

Chipping away at little bits

I have set up a new machine which is capable of bigger jobs ! I had been struggling a bit with the little proxxon, It is a very good machine but has limitations that you find especially when milling !

The new to me machine is the same concept with the mill but 3x the size and it handles much bigger jobs no problems….

Here’s the bores and mounting hole’s accurately placed - The bores I’ll hone tomorrow, they are just reamed atm and need a final finish

Then there is some millling to complete to the sides of the cylinder block to reveal the lug features and provide a landing zone for cladding later

Squeaky bum time finished and out of the way !!


I have honed the bores, Created the semi circular steam pockets to the cylinder tops and bottoms , Drilled all 8 steam passages, Milled the ports and exhaust holes to the side of the cylinder’s…

All went well , I have in the past taken too long drilling the steam passages independently of each other and sometimes just with a Dremel and taking it slowly it’s definitely viable but takes ages ! So I decided to fit a 3 axis vice to the bigger lathe and create a repeating set up for all 8 /2mm holes, This is definitely the way forward spending most if the job time setting up then the actual milling then drilling is very quick and easy! Just needed to use a torch and carefully break through into the ports…

Next up is the pistons , Trunk guides , cylinder top covers

A little more done on the project

On to fitting the parts soon

That's looking really good, you have made some great progress 

Cheers

A bit more done today, I’ve profiled the top and lugs of the cylinder block and drilled and tapped the 8ba Cylinder cover holes , Probably the risky bits out of the way ! I did break a tap building the GM version and used alum to corrode the tap out , I was very careful with the cast iron as that’s not an option if I break a tap off ….

Hi Chaps,

Back onto this little engine 😁

I’ve made some other bits  and pieces in between ..

Here’s some pictures of progress and some loose parts to finish off and fit .

The main engine mechanics are complete (Crank rods trunks pistons ect)

All turns over nicely!

One slight possibility of a problem with the main engine mechanics I might need advice on is the position of the cross heads….

I’ve double checked all the critical measurements, Rods, main bearing blocks, Base plate and columns …

Problem current is pictured below, To my simple mind the cross heads are popping out of the trunk guide too far! The columns are actually a little too short vs the drawing, I wonderful anyone else has had the same problem ?

Adding up some lengths, I think you should be seeing 0.109" or 7/64 of crosshead below the trunk guide for the longer 5/8" stroke version.

Check that you have not used steel base dimensions for oen part and cast base for another as that would account for 1/8" of extra stick out.

Does the engine turn over at the moment? If so what are the clearances like for the piston at each end of travel as dropping the trunk guides down could see the piston hit the top cylinder covers

Hi Jason,

I’ve definitely used the cast base dimensioning though out..

The engine turns over ready to go just the valve gear required now 😀

I’ve checked the piston gap at TDC and BDC at 2.2 mm ( I have 0.25 mm more clearance at TDC) I’m not likely to try and change that as is such a small amount.

My engine is 5/8 stroke which I’ve checked just in case that was off (bad crank)
The stroke is spot on for both cylinders, It’s almost as if the trunk dimensions are too short but I’m struggling to accept that the drawing could be off …

It’s very odd indeed as I have built a GM version and I can’t find a difference but the stroke , The GM version I had to lift the crank vs the base and shorten the rods by the same amount to clear the GM base as it was hitting it, I could have machined clearance slots but chose to re-dimension that one and it’s spot on… it has 1/2” stroke

Cheers R

Nice build, I enjoyed reading through the progress you’ve made so far.

As for the cross head guide issue, are the four corner rods the correct length? Perhaps the distance between the base and the cylinders is too large.

I just read your posts again and see you said they are actually shorter than designed… never mind 

I’ve just measured the stick out of the cross head at 5mm,
So roughly 7mm remains inside the trunk at BDC

Cheers R