Borderer Cast iron scratch build

I did think maybe the columns should be shorter for the 5/8 stroke but I don’t want to experiment and find the eccentrics are then too long as things are tight on space with this engine!

I’ve measured everything twice so to speak and I’m stumped 🤔

Cheers R

If you dont want to change the columns and it would be a major redo to remake the conrods, what about a washer shaped piece at the top of each crosshead guide to lower them down slightly?

Unfortunately I need them to go up… so a shim under the cross head to piston rod would not work…

About the only thing I can think of is a trunk shim with a male and female register.

I think that would work but a fair bit to make !

Cheers R

I'm  confused.  Shimming between the  crosshead guide and the cylinder would lower the guide, so the crosshead wouldn't  come out as far at the bottom. Or am I  missing something?

Same here. Packing between piston rod and cross head will not alter how far the cross head comes out, it will only move the piston up in the cylinder.

Options are, the last would not affect the current movement range of the piston and be the only item that has no knock on affect that would need other parts altering too.

- Shorten columns
- Raise Bearing pedestals
- Extend guides

Sit down with a bit of paper and lay out the heights from bed to crankshaft and then to underside cylinder. Then use two coloured pens to add drawing dims and those measured off your finished parts and compare where the two place the guide. I's say it is somewhere in the two height options for base types.

Ah sorry crubey , yes we were on the same page lowering the cross head guide / trunk!

I thought the suggestion was between the cross head / piston rod my bad !

Thanks for the suggestions Jason I probably will lower the trunk and as you say create a drawing to work out what the problem is and where it lies ..

Cheers R

So I’ve drawn up a quick front view,

And added the drawing dimensions in decimals

Calculated the gap expectations between the bottom of the trunk and base plate bearing pads, There are no other variables effecting this gap..

Came up with 1.4217”

My engine measured 1.4315”

This was using the cast base measurements as my crank bearing blocks follow the drawing for cast base too….

So the Columns are correct at 3 3/32 for a cast base

The main crank bearing C/L is sport on for a cast base

And the trunk guide stack is correct as per drawing

The con rods are spot on as per drawing

The hole position through the cross head is spot on as per drawing

I’m stumped but left thinking the cross heads too long towards the crankshaft,

Just checked and the cross head over all is 1.2.mm too long

Honestly it probably is most of the cause and I’ll take 1.2 off and call it !

Quote from: JasonbSame here. Packing between piston rod and cross head will not alter how far the cross head comes out, it will only move the piston up in the cylinder.

Options are, the last would not affect the current movement range of the piston and be the only item that has no knock on affect that would need other parts altering too.

- Shorten columns
- Raise Bearing pedestals
- Extend guides

Sit down with a bit of paper and lay out the heights from bed to crankshaft and then to underside cylinder. Then use two coloured pens to add drawing dims and those measured off your finished parts and compare where the two place the guide. I's say it is somewhere in the two height options for base types.

I did not suggest putting packing there - I meant between the cylinder and the trunk, lowering the trunk to cover the crosshead at the lower end.

It was Ricky who was saying between rod and crosshead.

As I said in that post your packer to extend the guides would have the least effect on other parts.

Quote from: JasonbIt was Ricky who was saying between rod and crosshead.

As I said in that post your packer to extend the guides would have the least effect on other parts.

gotcha!

Yes entirely my my misunderstanding lol 😂
Sorry Crubey

Next job onto the slide valves and valve rods today

Cheers R

I’ve made the slide valves and rods 😁 all looks good 👍

I’ve also ordered materials for valve forks and various nuts and glands .. I’m not sure how to make the Stevensons reverse gear various arms with bushes on them as I haven’t made a reverse engine to date !

I thought of making the flat part of the arms first and silver soldering the bushes on but keeping them un-drilled and over lengthwise for final machining once the soldering is completed, I have got a small rotary table (Proxxon) but it’s not really strong for removing bulk especially in steel !

Cheers R

if you turn some 1/16" spigots on the end of the bar for the bosses and put 1/16" holes in the flat stock that will locate them while soldering. I'd leave the bosses a bit long at this stage particularly the short ones. For the weighshaft have a long spigot to locate a "washer" on the other side of the flat bar.

hold by the boss in the lathe chuck and put the hole through which will remove the spigots.

Then clamp down to the mill table to bring the bosses to length.

Finally filing buttons or rotary table to round off the ends of the flat bar.