Potty Dake Engine

[sbwhart]

Well I've sortof made a start whilst I was making the link for the loco I had some long cuts to do so set the trips on the mill and just let it get on with it whilst I did a bit of work on the Dake.

The Dale is one of those engine thats best made from the inside out that way you make the part in the sequence they fit together so its just a matter of making each part fit.

So starting with the inner cylinder which is made from a 3" dia chunk of EN1A free maching mild steel.

Face of to thickness, and drill and ream a 8mm hole down the middle.



The turn up a 8mm mandrell a nice close fit on the cylinder, bolt the cylinder to it and skim the outside down to size.



Thats it for now, but every engine has to start someware 

Stew

[andyf]

I'll watch with interest and admitation, Stew. You do seem to like a challenge 

I might just be able to finish one like this, because it seems to be made from Lego:

Andy

[saw]

I will follow this with great interest 

[Stilldrillin]

You really have to be different, don't you Stew! 

Good luck with this build...... 

Following quietly along. 

David D

[sbwhart]

You really have to be different, don't you Stew! 


David D

My boss always says that:- don't know why 

Bit more done today

I was unsure as to the best way to progress on this, not quite sure what I would use the mandrel for but it just seemed a good idea to have one.

To mark out mounted the mandrell on the spin indexer used this to centre the height gauge then mounted the piston to it and used the indexer as a marking aid, the marking out is just for a sanity check that everything is going in the correct direction.



One of the problems with this engine is trying to get your head round what the important features are, I recon getting the side faces of the piston cymetrical and parallel but the crown of the piston is not so critical

So strating on the side faces, set the disc up in the vice

Using a parallel to get get it leve



 Find the top of the disc and zero the vertical slide on this, then mill the required amount off.



Flip it over and mill exactly the same amount off the other side. A quick measure showed that they were cymetrical within 0.05mm that will do.

Now to do the crown.  Set it up square in the vice using a 1*2*3 block this should be good enough.



Then mill as for the side.



This took all of my shop time for today this is it so far.



Stew

[sbwhart]

Some more done this morning.

To cut the steam ports the piston needs to be positioned correctly under the mill.

First in the  lathe and using an independat four jaw chuck set the bore running true.



Then mount the chuck on the RT with the RT set on zero clock one of the faces square by turning the base of the RT when level clamp it down.



Next you have to centre the RT under the spindle to do this I used one of those indicator things located in the bore.



With it lined up zero the DRO



Then using the a combination of the PCD feature on the DRO and the RT to generate the 31deg curve machine the ports by first drilling the ends 4mm and joining them up with a 4mm slot drill.





To drill into the ports mount the piston on the mandrell in the spin indexer making sure you get it square and with the mill zeroed on the centre line.



It is now an easy job to get the correct position to drill through into the port, just indexing round to get the position on each face, repeat for the location of the M3 holes.



To complete Tap M3 using the tapping table.



Thats the first part done.

Stew

[saw]

Stew, you are doing a greate jobb, but the most intressting thing with you is how you manage to find all of those remarkable constructions 
I have to edmitt I like to read youre blogg but I am not always understanding the mechanism. 

[sbwhart]

Cheers    Saw

Time for a progress update.

Made the side slipper bars for the piston I had some suitable brass bar in my stash.

Square it up and bring it to size.



Drill and mill the slots



And then it was  time I must have got one of the co-ordinates wrong for drilling as a result it was off set 1mm.

Rather than waist it decided it would come to no harm if I mounted the assembly in the four jaw and skim things level.





I think that came out better than the origonal, it 0.5mm thinner than I intended but that won't do any harm



Next part the outer piston/cylinder this part has a duel function it forms the cylinder for the inner piston, and also does duty as the outer piston.

I'm making this out of 5/16"*1" mild steel bar, first cut the bits off to length, then for the two side peices that the inner piston will work over, with them clamped together fly cut a light skim off, this takes care of the slight bend that was in the bar.



Keeping the parts in the vice so that the step at both ends is exactly the same as this helps to get a square assy, the vice was swiveled round 90 deg and the bar clocked level, doing it this way I could take advantage of the power feed.

Then mill the step to the same depth and to the correct width.



With this done the parts can be removed from the vice
Swivel the vice back and clock it square, and drill the holes and slot set the vice stop



Flip it over with the same edge against the stop and counter sink the holes.



Thats another bit done.



Stew

[sbwhart]

Thanks for you're interest chaps

Finished off the outer piston today.

Squared off the ends, and brought both sides to exactly the same length, had to take it steady as there was quite a bit sticking out.



Then drilled and tapped M3



Screwed it all together with stud lock.



Then over on the lathe in the four jaw skimmed both sides level and to size, had to make sure I was level in the jaws by taking a cut and checking that it was the same size all round, and adjust with a light tap.



I made the width just 0.05mm smaller than the inner piston.

Mounted the inner piston on the mandrell in the spinidexer and skimmed down each side to give a nice slide fit in the outer, doing it this way ensured it was cimetrical.



The outer piston slides in the outer casing, the sliding face needs to be square to the inner sliding face. So clocked the inner sliding face level on a angle plate.



Flip the plate 90 deg and skim up the outer sliding face.



Its an easy job to get the other face square and parallel by just sitting the good face on a 1*2*3 block and giving it a skim.



Quite pleased how that turned out.



The outer piston still needs the reces machining for the flange but I will do that when its assembled into the outer frame.

Stew

[Stilldrillin]

Stew...........

Will you be making anything I can recognise? 

I can see one of Rob's moulding boxes. Then you went an put a clock face in it....... 

I'm sure you know what you're about! 


Looking good, though! 

David D

[sbwhart]

Cheers Dave

I had to redraw the back plate mainly because I made the outerpiston from thicker 5/16 plate this would impact by reducing the clearance at the end of the stroke to 1mm so decided to increase the width of the plate to accomodate this change, also I realised that by not having adjustable jib strips I was changed the over all shape off the engine, so decided to increase the height so that it would look as though ut had jib strips fitted.

A made the back plate from some scrap yard 16mm thick ally jig plate.

First op square the plate up to size.



With the dro I find it easyer if everything is dimentioned from a common centre point also with my digital height gauge this also makes marking out easy.

Just zero the height gauge on the centre point, then you can make adjustments up and down to bring it on the size you want.



Just as a sanity check I centre poped the positions as an insurance I'm drilling in the right spot.

Set the plate up in the mill on some parallels so that I wouldn't drill into the table, and with a stop set up square to but the plate up against.

Find the edges of the plate and Zero the DRO on the centre point, first drilling op centre drill the zero position so that I have a datum point off set and centre drill for the bearing housing position, then using the PCD feature drill and tap 6 stud holes M4, and on the bearing centre line drill the edge of the plate to take 2*3mm dowels to aid alignment with the covers ets.




Then it was just a matter of walking round the edge to each poistion to drill M4 clearance and counterbore with a 5/16 slot drill to take the stud pads that will be fitted later.



The plate was too big to do all around it at one setting, so unclamp reposition and using a centre wound into the datum point and with the plate up against the stop, reclamp zero the dro on this new position and finish off the rest of the holes.





So far so good.



Now to maching the hole to take the bearing housing.

With my big four jaw independant chuck in the lathe with a wobble bar set up in the centre clock it up true to get position.



Just a matter now to put a bigger centre in the job drill the meat out then finish off to size with a boring bar.



Job done.



Still needs the bolting pads fitting and the edges rounding off so that it looks more like a casting, but I'll do that at final assy.

Stew

[andyf]

I'm fascinated!

Looking at your earlier post, all I can do is paraphrase Star Trek:
"It's a piston, Jim, but not as we know it..."

Andy

[sbwhart]

Looking at your earlier post, all I can do is paraphrase Star Trek:
"It's a piston, Jim, but not as we know it..."

Andy

Nice one 

Stew

[sbwhart]

The clamp holes and exhaust port for the front plate was machined up excatly the same as for the back plate.
For the anular inlet port I machined up a mandrel for a nice fit on the exhaust port.



Then mounted the chuck on the RT centred it under the quil and machined the port with a 3mm slot drill.





As a sanity check I tried the alignment of the dowel holes in the front a back plates.



Spot on 

I need to wait for the delivery of a 4mm long series drill before i finish of the front plate, so made a start on the bearing housing.

This is made from some 2 1/4" ally bar.

Face a centre drill then using a running centre machine down the OD. then drill through and bore out for the ball bearing pocket.



Swap in round in the chuck and protecting the finished dia with a strip of drinks can part off excess.



Clock up the register diameter.



And bore out the pocket for the other bearing.



Keping the job in the chuck swap over onto the mill and using that clock thing centre the quil up on the bore.



And drill the 6*4mm on the correct PCD.



And this is where it fits.



Another bit done.

Stew

[saw]

Wow excellent work 

[Rob.Wilson]

Interesting build Stew   

Sitting quietly watching .


Rob

[Stilldrillin]

I'm with Rob......

Mesmerised. 

David D

[sbwhart]

Thanks  Bennie/Rob/Dave

A little more done today.

I didn't like the look of the bearing housing far too square to look like a casting so set it back up in the lathe, and slew the compound over 5 deg and tapered the back end a bit.



That looks better



OK back to the front plate turned up the central boss to a tight fit in the exhaust port with the outside 50mm dia so that I can write the words DAKE ENGINE on it, and fixed it in place with some high strength loctite.



The plug only goes into the exhoust 5mm, I wanted to fit it first as the long air ways will cut into it. To drill the air way I used a 4mm long series drill.



Long series drill along side a standard jobber drill.

Clamp to angle plate centre drill and then drill part way with the jobber and finishe to depth with the long series clearing the chips as you go so that it doesn't jamb or break. I also ground one land of the long series drill long so that it would drill big so if it did break i would have a fitting chance of getting it out.



The inlet hole only goes as far as the anular port, the exhaust hole crosses the anular port into the exhaust port, to seal it off from the the inlet a thin wall brass tube goes down the hole to bridge the inlet anular port.



Stew

[sbwhart]

Well I'm a bit overwelmed by the interest this is generating.

So moving on to the next part the outer cylinder this is ally fabrication and is made the same way as for the inner cylinder.







With the square made I I found the centre and drilled the hole for the location dowels so that the end plates could be accuratly located.

As I doubted that the holes for the two end plates would be accuratly matched i decided that it would be best to spot the hole postions for the two plates seperatly using a tranfer punch.





The fixing screws holes were filled with Milliput epoxy stuff.



I then had to make a spacers to take the slipper strip this is instead of the gyb strips that the real engine has fitted.



Then make the brass slipper plates.



This is how they fit



And a quick hows it looking so far shot



Stew

[andyf]

Well I'm a bit overwelmed by the interest this is generating.

It's had 850 views so far, Stew, so there's plenty of interest.
It's just that our minds are so boggled  that we don't know what to say!

Andy

[Stilldrillin]

Well I'm a bit overwelmed by the interest this is generating.

It's had 850 views so far, Stew, so there's plenty of interest.
It's just that our minds are so boggled  that we don't know what to say!

Andy

He's right, yer know! 

David D

[DaveH]

Stew,

Fabulous - nicely done and shown, great photo's 
You go to a lot of trouble to take photos and post them. From me it is very much appreciated.
 
DaveH

[dsquire]

Thanks  Bennie/Rob/Dave

A little more done today.
.
.
.
The plug only goes into the exhoust 5mm, I wanted to fit it first as the long air ways will cut into it. To drill the air way I used a 4mm long series drill.



Long series drill along side a standard jobber drill.

Clamp to angle plate centre drill and then drill part way with the jobber and finishe to depth with the long series clearing the chips as you go so that it doesn't jamb or break. I also ground one land of the long series drill long so that it would drill big so if it did break i would have a fitting chance of getting it out.

Stew

Rest assured Stew we are watching and paying attention. Where else could I get good little tips like this to make things a bit easier. I continue to watch, read and learn Stew.

Cheers 

Don

[Rob.Wilson]

And a quick hows it looking so far shot



Stew

    cracking job Stew     Looks a canny size engine , are you building it to scale ?


Rob

[sbwhart]

Thanks Guys

I've gone through a period of self doubt with this one, will it work have I made this bit correct etc etc but I'm at the stage where I can do nothing but "Keep Calm and Carry On"

No particular scale Rob but it will look like the smaller sized Dake Engines that they used on pully blocks.


Stew