SOTHERN

[peatoluser]

Bill, I guess your right so shall go for option 4 and leave them unhardened.

Don, appreciate the complement, although after all that filing I'm now looking for a simple turning to do!

thanks for looking in

peter

[Stuart]

Peter

There is no need to harden the Stevenson launch links , even on a well used loco they will not wear.

There is very little block slip if the valve gear is correct , the only movement is when you move the gear to reverse or notch up


Best to make the die block of a softer material as if there is wear ( remote) it's the easiest bit to replace

Stuart

[peatoluser]

Thanks for the input Stuart, I shall leave them green.
ended up drilling the 'wonky' hole out , re-bushing and taking a lot more care in re-drilling 3mm.

for the valve rods I want to try and have them run in a square bush as in  full size practice.
making a square rod would be straight forward , but a 4mm square hole , another proposition altogether.
so I had a go at making the valve rod guides.
1st part was the bush. 7mm O.D. brass. drilled it out 3.9mm and started filing with some needle files.
I have a couple of cheap sets bought from various outlets , and this gave me two sizes in the square variety, one of which measured 3.8mm .
So I opened it out with the smaller file and then when I was getting near to size (nominal 4mm) , I basically used a hammer to tap the larger file through and in effect broach out the square hole.
it looked alright so decided to go with square valve rods.
the rest of the guide block is straight forward but fiddly. especially to solder
because its a compound engine, the guide for the HP cylinder needs to be longer.


next up are the valve rods themselves

thanks for looking

peter

[peatoluser]

well, I didn't make the valve rods next. As I had no stainless steel of the right size , I carried on with some more small fabricating in the shape of the weighshaft brackets.
there are three of these and are a straight forward soldering job much like the valve spindle guides



I hadn't left much room on the caps for the nuts to seat, so had to mill 2 little pockets either side for them. took more time to set up than actually do


although I have made a small clamping fixture for my bench drill, I don't like using it much for small drills as there's too much slop in the quill, and anyway, the top speed is only 2500RPM.
So I treated myself to a nice little proxxon TBM 220 drill. Small, accurate and can whizz up to 8500RPM.


note the quick and dirty vice. Part is held by a pair of wedges. With small drills (this is 9BA tapping) I very rarely clamp unless the part is too small to hold in my fat fingers! This vice gives me something to grab hold of while the part is held quit secure by the wedges.

here are the three pedestals. the studs are 9BA but the nuts are 10BA hex. but I do need to remake one of the split bearings. The hole is
not concentric to the outer.


thanks for looking

peter

[Roger B]

Good progress   

I have a Proxxon TBM220 together with the cross table (KT70) which is very good for coordinate drilling of small parts. I also added a fine feed to be able to do some milling.

[peatoluser]

yes, Roger, they're a cracking little drill. Really pleased with it. The only down side I find is that if a drill is just a little too big to fit in a collet,
it can be difficult to close the next size up collet to clamp it. Wouldn't be without it though.

With the valve spindle , I realised that the only part that needs to be stainless is the part that goes into the valve chest, so decided to make it in two parts. the main part in BMS and the spindle from 3mm stainless threaded to screw into the forked end.
this way it a) saves me buying stainless bar , and
                b)means I haven't got a long section of bar to turn down to 3mm dia.

the forked end was a simple filing job. I drilled a 12mm hole in some square bar, drilled and tapped for a grub screw.
It was then a simple case of clamping a bar in the holder and filing away. By rotating the block in the vice I could pretty well keep the four faces square to each other. It was the usual case of making filing buttons to round the ends. I should point out that I drilled and tapped the end of the 12mm bar before filing everything else!
heres the filing block and a finished fork end


but the next one will be made by different techniques ......



because I now have a new toy!!!...






thanks for looking

peter

[Roger B]

There is a 6mm chuck available for the TBM 220 which is fine for normal drilling.

Have fun with the new toy    Is it the fixed (rather than tilting) column type?

[peatoluser]

thanks for the tip about the chuck. I shall have to hunt one down.
the mill is a fixed column model sold by arceurotrade here in the UK.
I figure rigidity is the important thing with a mill. For any angular milling or drilling (such as steam ports etc.) I purchased a tilting table and one of those digital angle measuring devices . At least this way I don't have to worry about having to tram the column vertical!

peter

[Bluechip]

I have the same TBM drill. The chuck is here:

http://www.chronos.ltd.uk/cgi-bin/sh000001.pl?WD=chuck%20proxxon&PN=copy_of_copy_of_Table_Top_Tools___Accessories%2ehtml#a28122

Code SME1000 will get you 5% off IIRC

( Unless you get chucked out on your 'earole. In which case it doesn't.)

Dave

[peatoluser]

Thanks for the link Roger. I will have to get one ordered.

yours

peter

[Roger B]

This is the fine feed I made for my TBM. I now have a milling attachment for my lathe, but the modified TBM is still good for small pieces.

http://www.modelenginemaker.com/index.php/topic,2088.0.html

[peatoluser]

frustratingly not much shop time over the past couple of months, but I have been able to make some progress.
I have  managed to build the condenser.
the main body is a piece of 2" brass tube. I filed the ends square - figured it was quicker than trying to do it in the lathe and didn't quite trust my milling skills to do it on the new toy. But i did mill the grooves for the feet

and turned up the pipe and flanges for the steam inlet and outlet. these were then soldered onto the body one assembly at a time.
the ruler is just my way of checking by eye that things are reasonably square.
the proxxon came in handy for enlarging the pipe holes.
the outer covers where made from two discs of brass bar. To get the curve I made a couple of form tools from gauge plate.
the outer curve was pretty straight forward to produce on the peatol

but the inner i had problems with chatter and stalling but got there in the end

not the skinny off cut. I'm not turning a potential useful piece of breast into swarf if I can help it!
the two covers where then soldered onto pieces of 1/16" brass and the flanges turned and , on the rear cover , the middle trepanned out.

the front cover was more involved. this is ,on the inside , split in two. so i had to solder a bridging piece in first before I soldered the flange on.
I thought I had taken photos of this , but must have forgot.
the rear cover also has an inspection hole on it . this was quite straight forward to mill out now I've got me new toy. before it would have probably meant drilling and filing to shape because of the curved surface.

the two end flanges where straight forward turning and then drilling the water tube holes.
I soft soldered these onto the body.
then came the job of soldering in the tubes , and here I made a mistake. I saw some brass tube of the correct diameter (4mm) at one of the exhibitions but never gave any thought to the I.D. so bought enough more on a whim than anything. probably thought I'd be saving on postage. Anyway after I soldered them in I really noticed how small the bore is


I don't think it's going to be doing much condensing like that, so I've ordered a long series drill to at least open them out a bit.say to 3mm.
silver soldering I can do , but soft soldering is another matter as you can see. It also had to have the front face flat , and not trusting being able to clamp it securely on the mill, I resorted to spending some time using burrs in the proxxon and emery on a piece of glass to bring the face true.

and here is the complete condenser. Water enters the bottom pipe, flows down the lower set of pipes , and back through the top set and out via the top pipe while steam from the L.P. cylinder enters the larger upper pipe on the body and condensate is drawn by the air pump via the bottom pipe. well that's the theory anyway! at least it looks the part.

 and yes it was a pain cutting down to size 60 off 10BA bolts...tho' not nearly as much a  nuisance as finding out you hadn't made the flange deep enough for standard washers , so had to to turn down 120 of them...

thanks for looking

peter

[Roger B]

Glad to see you're back on this    How do you find your rotary table? It looks very similar to mine, which I had to tidy up a bit.

http://www.modelenginemaker.com/index.php/topic,5444.0.html

[peatoluser]

It probably is the same Chinese made type although mine turns O.K. but like yours does have some play. fine for milling but I think it might prove problematic for drilling PCDs. Having read your post I think it might prove beneficial to strip mine down . thanks for the link.

peter