Borderer Piston valve version

[Team ricky]

Nearly done ✅

Just one end to turn down to dimension

I was a little impatient because my original material was with a friend to see if a local chap could help , So I decided to order another small length of material and get on with experimenting really!

When I cut the the centre main journal I noticed I’d not carried the 1” over to final length so I brought a piece to short !

I still carried on to get a proof of concept if you will…

Now I’ve nailed every dimension I’m gutted it’s a bit short! I was half thinking to makeup 2 concentric silver steel extensions as the out puts either end , The shaft nominal is 9.5mm and the eccentrics can be bored bigger to fit over a sleeve , I worked out if I reduce the diameter to say 8mm the sleeves could be 11mm od

Then can be hardened for doing crankshafty things

Chip if anyone has ideas or has used hollow shafts !

[Admiral_dk]

Crank look good so far - but I'm not sure I understand your problem ....

Is the 'missing' 1" not for holding the Crank while turning it - or is it missing for driving something inside or outside the Engine ?

Per       

[Team ricky]

It’s a mistake I made adding the imperial fractions

No overall length was given and I missed carrying 1” of dimensions when adding!!

So essentially each end is too short to put a coupling on or flywheel!

I’m personally not so fussed about a flywheel but a good bit of shaft is needed for a coupling ….

I was thinking the extension pieces would allow for a flywheel later maybe!
If it won’t work properly or look terrible I’ll make another crank

[Team ricky]

One done ✅



Interesting it was good to get the method down and I did catch a problem early in finishing the opposite shaft end ….

I thought between centres I’d be ok to flip the part around and get access to turn down the last shaft end, But I luckily caught it not being concentric , Odd and couldn’t dial it no matter what I tried!

Flip back and it dialed perfectly, So my way out was to use the 4 jaw and a steady rest at the last know concentric area if you will and clock the middle main journal and lightly turn down the shaft,

Any pressure from a tail stock just messed everything up anyway so probably a good solution…

However I will make another longer one and leave enough extra to hold the work in the drive dog one end only for the whole job, I’ll then flip it when finished and clock in to replace the centre drill feature!

Unless anyone has an idea why it failed to be flipped and works that way !

[crueby]

Nice Work!

As to the not-concentric-when-flipped, sounds like the lathe tailstock may not be quite in line with the headstock and the ways. Easy to check - chuck a rod between centers, and take a light cut down its length. Then measure the diameters at each end and the middle. If all is aligned, the diameters will be the same. If one end is smaller than the other, then the tailstock is not quite in line, so you are turning a taper. If the middle is diffferent and the two ends are the same as each other, that would be due to the bar deflecting from the pressure of the cutter - common issue if the bar is thin. For that condition the best you can do is to take a few extra passes without moving the cross slide in, to even out the cuts. Most likely, the tailstock and headstock are not quite in line with each other. Depending on your lathe brand, the adjustment is either in the tailstock base or in rotating the headstock till the cut diameters match each other. If its cutting a taper like I suspect, flipping the part end for end will amplify the difference.
Chris

[Team ricky]

Ok cool 😎

Thanks for the pointer !!

When I got the lathe I noticed it had no tail stock adjustment so I figured it was set up another way at factory…

It is the longest work I’ve made so it figures the error has shown up ! Research needed !

[Admiral_dk]

People often put spacers in between the webs to compensate for the pressure from the Tailstock.
Some hot-glue them in and other make them adjustable - to make sure that are an exact match.

Your result looks fine 

Per     

[Team ricky]

That’s a good idea to pack the webs

I was very careful to just lightly engage the tail stock and it still influenced the dial out the moment the centres engaged!

I did the alignment checks today and it’s definitely a wierd one ☝️…..

I used the dead centre in the head stock taper and the live centre as I’m using it to point at each other , by eye carefully checking it looks good but however the long cut test failed as it cut deeper as I approached the head stock end …

Short outcome is no adjustment are given on the tail stock and the hand book shows no head stock adjustment so I simplify shimmed the engagement between the tail stock and the ways , tested and tweaked to get a straight cut , it’s 0.1mm shim under one corner for a straight cut over 6” or so - pleanty good enough for me

Started the longer crank today also!!

This one’s silver steel so I was wondering if you guys think having it hardened after production is a good idea ?

Nickel plated seems like a plan too

[crueby]

Hardening the crankshaft would be tricky - too hard and it gets brittle, it would need to be tempered properly too to let it flex without snapping. For a steam engine model, hardening is not needed at all, especially with bronze bearings all round.

[Admiral_dk]

Unless it will have a very high wear rate or very high load - I think the majority here will tell you to leave it as is. As there is a chance of it warping during the Heat-Cycles (or should I say fast cooling) - those who harden it usually make all the critical dimensions a tad too big and then grind them to spec afterwards ....

I'm Not telling you that it can't be done or won't work - but it can be a lot of extra work on the item without much in return.

Those pieces that really needs to have the full Heat-treatment - will have to have the whole process done ....

Per       

[john mills]

to use silver steel i prefer it in a heat treated condition before machining but hardened and tempered so it is still machinable 40RC 45RC
in this condition it will be tough and have, better wear  quite a few alloy steels need to be heat treated to machine often supplied in
a condition for better machining in an annealed condition as supplied when required for bending and welding they are terrible to machine
i worked were there was lots of scrap 8620  some pieces would be heat treated to around 36 rc  so it would machine much better
silver steel heat treated first tempered back is a much better steel.But before machining  .
John

[Team ricky]

Sounds like a good way to machine easily!

I might do a test piece for the eccentric parts


Here’s the final part, I did remake in silver steel to the correct length, all journals I went with a metric reamer size (7.9mm) as a posed to 7.95 (5/16”)

I’m not sure on bearing clearances but most of the time the reamers seem to over cut very slightly, I have got a tungsten carbide micro boring bar so if needs be I’ll make the bearings just with that !

[Team ricky]

Forgot to mention if anyone has carried out nickel plating at home ?
Just with vinegar salt and a phone charger !?

I’m not down for the chemical kit for £50 but I could try the diy way !

Alt send it away to be done ✅

[Kim]

Chris, one of the members of this forum (Crueby) has done a lot of nickel plating.  You might check some of his threads.  I believe he's provided a nice explanation of how he does it here somewhere.  And he wrote an article for Live Steam & Outdoor Railroading Magazine on it too.  That should give you some good info.

Kim

[Team ricky]

Excellent thanks for the pointer !!


I’ve decked the base casting and drilled and tapped all the holes

I may do the columns tomorrow and mount the cylinders!