Another Paddleducks build log

[spuddevans]

Well I started off today by drilling the thru-holes for attaching the steamchests and for the steam porting, and then tapping the inlet flange fixing holes.

Then it was time to use a 6mm machine reamer to clean up and finish off the piston valve bore's. Prior to this I have only used hand reamers that kinda centre themselves just using a tap wrench to turn them. However, machine reamers are a different kettle of fish ( or so I am led to believe ) they need to be accurately aligned to the bore.

This was still a new experience for me, mounting a previously drilled item back into the vice and then centering it accurately to the spindle. So this is how I did it.


I mounted a Dti in the chuck but offset it slightly on its mounting so that the spindle can be turned 360 degrees and the finger will still stay in contact with the wall of said hole. Then by sweeping it round and nudging the x and y axis until the needle stays still through a whole revolution. Then lock up the axis and  watch the needle deflect, unlock axis and estimate deflection and then compensate and then re-lock. I managed to get it to within 0.005mm which I thought was ok.


This may be a little  but I thought I'd just share a little thing I do when removing or changing tools on my little mill. I dont know if I'm the only one, but when changing tools it seems like you need about 4-5 hands, one to hold the tool in position, one to hold the spindle lock and one to tighten up the chuck, and if that is not hard enough, when it comes to remove the tool, say an end mill, you have one hand holding the spindle lock, the other is pulling on the spanner to loosen the chuck, then as soon as you loosen the chuck by what seems like a gnat's whisker, said end mill drops at the speed of light and drops on the vice chipping at least 2 of the cutting edges/teeth, whereupon the endmill will bounce onto the concrete floor. Do this a couple of times and it can get kinda expensive. So this is what I do.


Just lower the mill's head and rest the tool on a sacrificial piece of ali so that the tool cannot fall completely out of the chuck.

I'm sure that all you experienced machinests out there do this or an even better method, but this is new for me.


Anyway, back on topic.


Then I broke the whole engine assembly down to bits as soon I would need to work on the main block to drill and tap for the steam chests. That done I milled away some decorational clearances at the top of the steam chests. I still have a little shaping to do to these as can be seen from the hatched markings. This is just a rough marking, I reckon I can't go quite up to the line as it may break into the main bore of the piston valve, but this gives a rough idea of what I'd like to achieve.



Then Stefan (Spynapples) popped round and gave me a helping hand.

Together we rough cut some 2mm brass sheet for the steam chest blanking plates, then we milled them into shape, and then we milled a 3rd one to replace the rather diamond shaped one we cut earlier without properly squaring it. 

Then, lacking some superglue to temporarily hold the blanking plates to the chests, we used an engineers clamp ( at least thats what I think its called ) to clamp the plate to the chest and then spotted thru to mark the holes, then we drilled both plates.

Then it was on to drilling the main block for the steam chests. With the lack of superglue spontainiously appearing in the workshop, and with the whole block and steam chest arrangement being too long to use my engineering clamps on, we mounted the assembly into the vice, carefully lining everything up while tightening up the vice. ( having an extra pair of hands was very helpful here )

But this meant that we could only spot thru on the upper mounting holes, this we did on both ends of the block. Then we drilled and tapped the 2 upper holes of both ends. Then we were able to mount the steam-chests using the top mounting holes with some M2.5 screws and then when all aligned up right we spotted thru the bottom mounting holes, and then drilled and tapped those holes.

Finally after all that we ended up with this.



That's as far as we got as the call of the wild inturupted, well the call of our stomachs anyway 


Tim

[arnoldb]

Good progress Tim 

Cheers 

[bogstandard]

Tim,

Very nice indeed, you are really showing so nice machining in this post. Logical and straightforwards, with no rushing.

It is always easier with another pair of hands to assist. When I was making my engines, I had to use anything I could to help. I was working in those days with my left hand and two fingers on my right, with my right forearm swivelling from the waist, as the top of my arm was immobile. Hence superglue and other little tricks.

John

[spuddevans]

Thanks Arnold and Bogs

Logical and straightforwards, with no rushing.

I am absolutely no good under pressure, I perform best when under absolutely no pressure at all. So when in the workshop I always try to take my time, I find its always quicker to do a task slowly than to do it quickly twice.

It is always easier with another pair of hands to assist.

That is very true, and I was very grateful for Stefan's help today, especially in setting up for spotting thru the steam-chests.

Hence superglue and other little tricks.

It is a great tip, using superglue, when I was woodturning a lot I used to use hot-melt-glue a lot in the same way for tempory holding.

I keep meaning to pick up some superglue, everytime I come out of the store I have everything else I didnt go in for but not the one thing I went in for

Stefan's promised me he has some that he will bring the next time he comes over. 


Tim

[ozzie46]

Looking good Tim, You will have a runner shortly I betcha.

 Ron

[kvom]

As for the reamer, I would have done the following:

1) Chuck the drill in the mill

2) Slide the part's hole onto the drill.  This will align it vertically

3) With the part still on the drill, maneuver the table so that the part is flush with the fixed jaw of the vise

4) Clamp the vise onto the part.

Replace the drill bit with the reamer and carry on.

Of course, it's almost always better to ream a hole while it's clamped in the vise at the same time it's drilled.

[chuck foster]

this build is moving along real well   

it won't be long and you will be finished 

chuck 

[Stefan Pynappels]

Tim, you're very good at making a numpty feel like he was actually useful! Thanks for not telling them I messed up one of the valve pistons through not reading the instructions.

I'll try and have the superglue out for the missus to bring home on Wed.

Had good fun anyway, thanks for the shop time!

[spuddevans]

Thanks for not telling them I messed up one of the valve pistons through not reading the instructions.

You know, I'd completely forgot about the piston valve when doing the  writeup

We did make a start on the valve, but just to correct Stefan, it was me who did not read the instructions. We did start by turning down some 6mm stainless to the required 4mm, then at that point we turned the page and read the instructions about drilling the holes / tapping one end before turning down the rod. So we parted off the 4mm section and rough cut the 2 lengths of stainless, chucked one up, faced it at one end and then we drilled the 3mm hole to a depth of 24mm.

That was when the call of the stomach kicked in and we called it a day there.

So if there is a lesson to be learned, always read the instructions/plans through for each part just before you start cutting metal, and read all the way through to the instructions for the next part, just to make sure that you I have not missed out any helpful hints and tips.

Had good fun anyway, thanks for the shop time!

You are more than welcome, you are most welcome to come and use the tools and machinery here, and you are even more welcome if you bring scrap bits and pieces

Tim

[bogstandard]

Tim,

The spools themselves are really about one of the most important bits to get right.

Get good measurements as I have shown how to do, and make accurate cuts. If you need to err on the side of caution, make the cutaway shorter. What you don't want to happen is have both ports uncovered at the same time. It is better to be 0.1mm shorter than 0.1mm longer on the central cutaway. Also, don't chamfer the edges of the cutaways, keep them as sharp as possible, but without burrs.

Just trying to help a little.


Bogs

[spuddevans]

Get good measurements as I have shown how to do, and make accurate cuts. If you need to err on the side of caution, make the cutaway shorter. What you don't want to happen is have both ports uncovered at the same time. It is better to be 0.1mm shorter than 0.1mm longer on the central cutaway. Also, don't chamfer the edges of the cutaways, keep them as sharp as possible, but without burrs.

Thanks for those tips, I will attempt to follow them. I have now read and re-read the parts in the book about the spool valves, and I will read them again before I put tool to metal.

Just trying to help a little.

and I appreciate you taking the time, I can surely tell you it is of great help to me

Thanks Bogs,

Tim

[ozzie46]

  Next to the upcoming  control valve, these spool valves caused me the most concern. I took my time and they seem to be ok. I have no gaskets or sealing on  the one I have test running and it runs with a little less than 10 psi with about 3 hrs running on it.

  Ron

[Stefan Pynappels]

Hey Tim,

I got a 50g bottle of thick superglue for you, was all I had left.

I also found my thread gauge from when I worked for Wurth, it has Whitworth 55deg and Metric 60deg gauges on it, I'm sure it will come in handy.

There are also 2 dead HDDs.

The missus can take them on Wednesday.

[spuddevans]

I have no gaskets or sealing on  the one I have test running and it runs with a little less than 10 psi with about 3 hrs running on it.

That sounds great Ron, glad to hear it'll run on such a low psi even without gaskets or sealing.

I got a 50g bottle of thick superglue for you, was all I had left.

That's great, thanks very much, that'll come in very handy 


I got a little more done today and got the 2 piston valves made.

Started where me and Stefan left off, having just faced and drilled the 24mm deep hole. So I turned around the piece and faced off the opposite end to the required length, 46mm as I recall . I then drilled it with a 2.1mm bit and then tapped it M2.5 ( I know the plan said to drill 2mm, but not having the same confidence with tapping stainless, I just went with a slightly bigger drill to ease the strain on the tap. According to the tapping chart I have, 2.1mm is still a strong fit )
Then with a bit more of the 6mm rod sticking out of the chuck, I turned it down to 4.05ish mm for a length of 26mm, then polished it down to 4mm with some emery. It actually has a very slight taper, I say slight as when measured with a mic it tapers from 4.013mm to 4.006mm, I figure that it wont make too much of a problem ( he says hopefully  )

Then I re-chucked it, gripping it by the 4mm end and faced the free end to leave me with 19mm of the 6mm diameter left. ( my measurements according to the plans were 18.97, but the plans said it's better to be slightly long so I went for 19mm) Then after marking 3.5mm from each end of the 6mm diameter bit I roughed out the centre bit, and then slowly brought the 2 ends to 3mm. Here's a shot of the 1st end brought to size.



Then I did it all again to make the 2nd one.

Then it was time to drill the little cross holes and so I used the spin indexer to hold the valves as I centre drilled and then drilled thru with a 1.5mm bit.




That's all I got done, next will be the eccentric straps, and that will plunge me into the world of silver soldering. ( that reminds me, I must pick up a couple of firebricks to make a hearth. )

Tim


EDIT 13/03/2010 (for those reading this thread and wanting the build this engine.)

I have been trying to get the engine to run and had nothing but escaping air to show for my efforts. I have traced the problem to these piston valves. I originally used 6mm stainless rods to make the piston valves out of, having just now measured the piece of 6mm rod used to make them I find that the rod is actually 5.9mm and that 0.1mm allows a lot of air around it.

So beware when using raw material to make sure that it is the size you need. I ended up turning down some 8mm steel to make the replacements.


EDIT 6/8/2010

Something I have found when trying to get this to run is a problem with the piston valves sticking, and I eventually chased down the problem. It seems that when you drill the cross-drilled holes there is an edge raised up around the edge of the hole. The solution was to just give the piston valves a Light wipe with a fine cutting file and then a wipe of some w&d while they rotate at a slowish speed in the lathe.

[NickG]

Good stuff Tim, it's looking great.

Funny you mentioned about needing several hands to put end mills into the ER collets! I found the same myself the other day!

 Sorry, bit here: We went to metro centre to look at new cameras on sun. Came back with one we didn't even consider. Will post some more info in a different thread as my waffling took up more space than I thought!

Keep up the good work.

Nick

[bogstandard]

Nick

Funny you mentioned about needing several hands to put end mills into the ER collets! I found the same myself the other day!

That is the reason I rave over the ballraced ER closing nut. You can tighten it up by hand enough to grip the cutter (even very loose ones), then come back and use the C spanner for the final tweak.

The other way if you have a normal nut (unless you grow another hand), is to put a bit of brown stuff (wood) to rest the cutter on and in place while you tighten up.

Bogs

[NickG]

Bogs,

Didn't know they existed, must have missed comments about those. Where would one buy one of those, or is it just part of a more expensive collet chuck?

Nick

ps I have to use some brown stuff for the base of my engine soon. I don't like wasting proper materials for things like bases!

[bogstandard]

Nick,

He only gets them in limited quantities, so they are not available all the time.

http://cgi.ebay.co.uk/ER32-collet-chuck-Ball-Bearing-Clamping-Nut-Quality-NEW_W0QQitemZ220478456389QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item33558a4245&_trksid=p4634.c0.m14.l1262


Bogs

[sbwhart]

Nick

I got one of them ball bearing clamp nuts after John sowed me one, a great buy makes tool changes easy, and they grip the tool like a Gorilla gripping a banana  .

Have fun

Stew

[NickG]

Cheers guys, there's an ER 25 one too.

I need to make a big list of things I need!

[Stilldrillin]

Thanks for the reminder John! 

I got 1 on it`s way to me...... 

David D

[spuddevans]

Well I've spent a bit of a frustrating afternoon. I started off ok with cutting out some 4mm brass for the eccentric straps and then milled the pieces square and to size. No problem there.

Then I set up a vice stop and positioned the mill table for centre drilling all 4 parts, and then centre drilled all 8 holes ( keeping up are we ?? ) That went ok too. Then I started by drilling the 2mm thru holes, and this too went ok until the last hole when the 2mm drill bit snapped halfway thru. "Easy" I thought, just turn over and drill thru from the other side. So I turned it over, centre drilled and then very cautiously drilled thru using the same bit that broke ( having just resharpened, well re-shaped the broken end on the grinder freehand, probably not that sharp and definately not the same profile, but it was good enough to finish a hole that was half bored, or at least that's what I thought)

I gingerly drilled thru to where the old bit was stuck, and hearing the telltale sound of drill on harder material ( hitting drill not brass ) I withdrew the drill and knocked the drillbit fragment thru with a fine punch. Then to finish the hole off I attempted to drill through with the same re-sharpened bit. Wouldnt you know it, the darned thing snapped the drill again  Fortunately the hole had been drilled enough and I just had to knock out the 2nd broken bit. So I thought that must be all the problems over and done with 

Then I started on drilling the blind holes that are to be tapped, and got the 2 holes in the 1st eccentric strap drilled without any problems or drama at all.

Then I think it was at this point that I must have been getting too smug with my own ingenuity in overcoming all the preceding problems, thinking that everything's just so easy and plain sailing. I was drilling the 3rd 1.6mm x 6mm deep hole ( to be tapped M2 ) when the bit snapped  "not another bit!!!". After a bit of head scratching and thinking of how I could recover the part it occured to me that I can just bore the holes in the other end and cut off the bit where the snapped off bit is when I shape the top of the strap.

I didnt have a spare 1.6mm bit, but checking my tapping drill chart I saw that 1.7mm is ok so I drilled the opposite end and then tapped the holes.

Now here's a kick in the teeth, Just after tapping the M2 holes I happened to turn over the part and you wouldnt believe it, the darned broken bit of the drill had fallen out 

Not taking heed of all the signs telling me to quit while I was behind, I pressed on and made a start on boring out on of the straps. I didnt have any M2 screws that were long enough I used some M2 allthread and some M2 nuts. Not having the stepped cutter that John used, I progressively drilled out to 13mm ( my biggest "small" drill ) and then used my boring bar set to enlarge to a little over the size of the smallest eccentric.

Taking it out of the vice and seperating it I then found that the eccentric groove is every so slightly smaller than 4mm Not having a way to chuck the eccentric to slightly enlarge the groove, the only other option is to reduce the thickness of the strap a tiny bit. The strap fits the eccentric, but it is a press fit and totally impossible to rotate. I've sanded it down using some W&D on my granite plate, but it's not reduced enough.

I guess I might try flycutting it down by a tiny bit. But at this point I decided to heed all the signs and retired for the day. Sorry for no pics in this post, but when all started to go wrong I forgot about taking pics.

So, not much progress to show, but I guess I've learned from the experience.


Tim

[bogstandard]

Tim,

When it gets that bad, throw your hands in the air, bow your head in shame, and give up for the rest of the day, if you don't, you should know by now, it will only get worse.

Been there and got the t-shirt, many, many times.

BTW, you can make the straps any shape you like, as long as they fit and don't hit anything when in operation. I only made them that shape because it would be the easiest (?) way for a beginner (or so I thought).

John

[spuddevans]

When it gets that bad, throw your hands in the air, bow your head in shame, and give up for the rest of the day, if you don't, you should know by now, it will only get worse.

The voice of experience there. My inexperience is what drove me on this afternoon, I now know that when things go wrong like this again, take a step back and walk away ( muttering, if that's your thing ) and leave it for the day.

Well, if nothing else, at least I've learnt that lesson, and at least it didnt go all pear shaped on a big / hard-to-make part. ( that's my attempt at looking at the bright side )

Tim

[NickG]

Tim, I often wish I'd taken a step back and slept on it. As you say, my inexperience usually drives me on too, hence finishing both of my last two nights work after midnight. Coming away has been a blessing in disguise to catch up on some sleep!

I would just keep rubbing the strap on some emery cloth, or even draw file it rather than try to flycut it I think.

Nick