Here is a list of all the postings Iain Downs has made in our forums. Click on a thread name to jump to the thread.
|Thread: Steam Engine Number One|
There've been a few sessions in the workshop since my last post, but I've not had a chance to post them up.
I found I'd gone a bit too far to follow some of Jason's advice. I already had a cylinder of sorts so roughing out at 45 degrees didn't seem like it was worthwhile. However, the idea of taking a deeper cut to use more of the mill struck me as eminently sensible.
Despite this being sensible, it proved a little too much for the poor mill - to be more accurate my 3D printer! IN an earlier episode, the motor drive gear had give up the ghost and I'd replaced it with a 3D printed one, which has supported my endeavours tidily through the past few months. However, this was too much for it.
Poor thing. I did attempt to superglue it back together, but this lasted but moments. As the shattering of the gear resulted in the key (conductive) ricocheting round the box which contained the motor controller (electric!) I decided that prudence was the order of the day and reached out to ARC for spares.
Why not print another one you ask? Well I didn't but it was not a good print. I think my printer needs some maintenance - I find them temperamental things.
Usual excellent service from ARC and a couple of days later I had the cogs, but other things got in the way and I only returned to the task today.
Because I had to leave some metal for drain taps, I'd decided to carve out the cylinder 8mm short of the end flanges and then separately carve out the remaining 8mm (apart from the tap mounts) with a snub ended mill. I'm told that one should try and avoid sharp edges! My first snub nose use...
And finally, the finished product!
To finish this off, I need to mill out the valve ports, lap the valve face and drill the end cap mounting holes.
I might leave that for a while and get started on the big connecting rod assembly. Which means back to the drawing board as I need to finish of some changes.
In a spirit of masochism (for a Yorkshireman), I weighted the part. A tad over 1Kg. which means I've flushed away 90% of the cast iron I paid for! That hurts...
I'm afraid I couldn't work out how the vents channels worked from the picture in that page. I suggest that you need to find (or make) a drawing of what you want to do and ask for advice. I suggest you start a new post which may attract more responses than if it's just embedded in this thread!
|Thread: Making split bronze bearings [ silver soldering ]|
Just to add a little digression to the thread here.
I've recently made a pair of bearings (cast iron) and split the cube 4 ways and then glued (off the shelf superglue) back together before boring.
This (as far as I can see has worked well). A modest amount of heat (and a sharp tap) broke them apart and a little alcohol cleaned them up.
I'll do this again!
|Thread: Steam Engine Number One|
HI Gas Mantle.
I'm delighted if this thread is interesting to you!
The only thought I had was to ask you about the cylinder design. With a 50mm bore, 5mm wall thickness and a 10mm flange (which is what I have) plus the valve face I needed a 100mm bar to get it all in.
So continues my drive to discard the large part of a perfectly good cast iron cylinder.
In the previous post I'd machined the top of the valve port. Next was the sides.
I did this in steps of about 10mm with a 1mm DOC.
And the finished block (for now, probably needs a bit of tidying once the rest of the bar is removed.
Next: How on EARTH am I going to mount this vast chunk of metal on a rotary table on my tiny mill?
That's the general idea. A chuck is impractical for a number of reasons. One of which is that by the time I have a decent sized chuck on there and mount the cylinder, the cylinder would be off the edge of the table! Another is that I did not think that the 5mm flange would provide enough grip. Boy was I right about that! (more on that later).
In the end I decided to use an MT2 blank, a clyindrical spacer and a clamp on the top.
This gives and idea
The MT2 blank (drilled and tapped to M10 is held in by a 10mm bolt, the cylinder fits snugly on the spacer cylinder and another M10 bolt clamps the top of the cylinder - as below. As seems usual, I'd underestimated the spring in the boring bar and ended up cutting the inside a bit too much making it rattle somewhat. However, a 0.15 shim (feeler gauge) slipped around the blank fixed that nicely!
You can see why a normal chuck just wouldn't work!
Also in view is my Heath Robinson mill end stop. A couple of clamps bolted down and nice little vertical rod on the Y axis to act as a stop.
I said above that the other reason that I couldn't mount it on a chuck is the lack of grip. There is a LOT of vibration when removing the outside of the cylinder. The Z creeps up, the handles fall off and the X can shift too (so I need one hand to hold the X axis, one to hold the z axis and one to turn the wheel - hang on....!)
What's more challenging is that it's actually shifting the rotary table on the mill table, even after adding stops and clamps to it. In fact that's where I gave up today. I have to work out how to hold it in place more rigidly.
Or I could revert to taking very small cuts but this is already taking forever!
A mill and a rotary table will NEVER replace a lathe...
The benefit of unemployment is that it gives me a bit more of a chance to create cast iron dust and I duly managed this today. One hopes to keep working on the Steam Engine, but the wife wants me in a job. Sigh...
About my first book on engineering was one the Mr Hall's books. This one on milling. In it the first thing he says is that the main challenge in milling is working out how to hold the workpiece.
I'd agree with that, and it took quite some puzzling to work out how to hold the partial cylinder accurately with the thick piece uppermost. One of the things I realised is that it didn't much matter if I got the exact thickest part uppermost provided that I could get a wide enough cut for the valve face.
So this is what I came up with.
The ally bar is to raise it a bit (for assembly, then removed). The two Stevenson's blocks are clamped to cylinder ends which are (I hope) normal to the bore. Finally, the rotation is checked with the T square - you can just see the scribed line if you put your good glasses on!
Next to mount it on the mill
The reason for raising the piece is mainly so that i can get the indicator at (more or less) centre height.
Finally, the drudgery of slicing of the top at 1mm doc at a time. With a 3 flute carbide mill that goes quite nicely albeit slowly.
So next up is to square off the sides. I', trying to work if I should cut the valve ports on the top now, whilst It's in place or if I should wait until I've thinned down the outside.
I'm also seriously wondering how I'm going to mount it on my 4 inch rotary table. On the rather small worktable.
I was hoping to (somehow) use my Christmas present tailstock, but that really won'f fit. I suppose the good news is that I really am just throwing the outside away so there's no particular need for high accuracy.
Describes me to a T.
Not too serious, terribly inaccurate and overambitious with projects...
But many thanks indeed, Paul.
We left the last post with our intrepid hero concerned that he might have broken his lathe.
It would seem that the interrupted cut was too interrupted (or the hero too brutal?) and the sacrificial motor pulley had duly thrown itself on the alter of sacrifice.
I did give some thought to printing a new one, but given that (in theory) the pulley was designed to break the internal key and not the motor, I wasn't sure that it would have quite the same shear characteristics. So out came the chequebook (metaphorically) and £6.50 worse off I got a replacement (I got two actually - one way of making sure things break is not to have a replacement).
With that I set to and finished of the lathing part of the cylinder.
As the cylinder was now held less securely in the chuck (just the 5mm of the flange) I wanted to make sure that it was held in place hence a rod through the headstock pulling it against the chuck. As you see below.
Once I'd got the outside trimmed down I could finish of the end proper with out the bolt.
So the 'finished' product...
The cylinder is about 0.25mm too short. This is due to something that happened just before the finishing cut when the cross-head seemed to jump forward for no apparent reason. Clearly this was something I did, but I really don't know what. Perhaps I nudged the dial with an elbow. A bit annoyed at that as I was creeping up on the exact length (to the various limits of my ability and measuring devices). However, it's not going to stop it working.
Now all I need to is remove 2/3rds of the remaining metal on the mill. Shouldn't take too long on my CMD10....
|Thread: Metal Cutting Power Saw|
That would explain why my Aldi chop saw grunted, sweated and smoked whilst going through a 2 inch square aluminium bar....
I've found the Aldi chop saw (an angle grinder on a frame) very good. I suspect it would be easy to overheat it with big cuts, but I've got through 2 inch square steel with it, albeit with a bit of turning round.
It was about 50 quid. Moreover it's fast.
I suspect these aren't in stock now, but there are a bunch on eBay which might do.
|Thread: Steam Engine Number One|
After spending a goodly amount of time watching my hard earned pennies turning into cast iron dust, I've finally got the bore through the cylinder.
As best I can tell I've managed to bore this to exactly 50.00 mm. I'm measuring the bore with (Aldi) digital calipers and I'm confident neither in their accuracy nor in my ability to use them with this precision. Still....
One thing I realised after i'd started the whole process off was that the bore was wider than the gap left by the 4 jaw chuck.
Accordingly the last 3 or 4 mm were not bored all the way through. This isn't a crisis as I need to take a bit off the end anyway. At least I hope it's not a crisis.
The next step is to turn it round, reduce to the right length and cut the other end flange. As I have only a 5mm ridge to grip onto (with an 85mm long chunk of metal) I felt that I should secure this better.
The idea is to have a disk which I can clamp through the central bore. Not having anything particularly appropriate, I took a 50mm square aluminium bar cut a bit off the end (my chop saw does not like me now) and trimmed it.
I can remove and trim off the what's left once the challenging intermittent cuts on the outside are complete. I hope.
Note, regular readers, that I managed to insert the collect correctly in the holder this time!
And here it is sort of complete.
I was going to carry on, but my lathe appeared to develop asthma. It wheezed and grunted and refused to get up to speed.
I could stop the spindle with moderate finger pressure.
Since, I've left it to cool down (though it's not been working hard) and went back an hour later and it seems OK.
I may well be begging for help on this in the forum, but I'll make that a separate post.
OK a bit more done.
Following my Sage (Jason), I've drilled a bit with 6mm then 10mm then more with 6mm and so on until through. Then a push through with a Blacksmiths drill.
On thing which I saw here is that the drills seemed to swing up and away as it entered deeper into the hole. This particularly with 6mm as the 10mm filled the space.
I don't know if this is just the torque pulling it out of centre or if the tailstock is contributing to this. I have measure the tailstock as about 0.25mm higher than the headstock on a test bar and with a 2MT just this week found that the bar points upwards from the tailstock by about 0.1mm in 100 mm.
Having a good sort out of the tailstock is on my todo list (bolstered by a purchase at Doncaster 2 years ago of a lapping plate I've not used!). But it's going to need a bit of girding of loin cloths to get the courage to start it!
Next was to bore out. FIrst with a smallish carbide boring bar and then with the hss indexable boring bard seen in earlier posts.
and here's my boring bar. My first attempt at a tool bit wasn't very good and it needed careful alignment so as not to scrape in the early stages.
But, dear God, this is going to take a long time! The raised part is more or less where the cylinder bore should be.
Number one skill for model engineers? Manual dexterity? no. technical drawing skills? No. Mathematical insight? No.
I'm either too close to retirement age or too far away depending on whether I consider my actual age or how many more bloody years of work there are...
The guys I've been speaking to recently seem content that they can provide a 6% return on my pension funds before retirement and that's after all charges. That's not a zero risk option, of course, that probably pays close to bugger all.
We're going to be making a decision on an IFA and pension shift fairly soon (like by next week) who will then want reams of paper from us.
No doubt the claimed return will drop for some very plausible reason once we sign up.
|Thread: Steam Engine Number One|
And not content with finishing the crank, I immediately started up on the cylinder.
I mounted it on the lathe in a four jaw and centred it on the markings I'd set in a previous job.
I must say that seeing that enormous chunk of iron on what is a fairly small lathe was a bit daunting. I'm slightly worried about it handling a 50mm bore through the length without shifting.
For today, however, the task was to cut out the flange at one end of the block. This I could do with a centre adding some support, though the sheer size required me to cut a wierd shaped tool so that I could physically get to the material in the right place (and still provide access to the centre and tailstock.
There's a depressing thought here about how much cast iron dust I will be making in the next phases. More than half the volume. Do you think I can sell it back to the supplier?
I'm afraid I'm going to have to ignore Jason's (most excellent) advice on drill speeds. If I were to run this at 800 rpm, the lathe would walk out the door - probably over my dead body!
I can get it up to a bit under 300 rpm before the vibration gets too much. the work above was done at around 200 rpm with fine cuts (0.25mm) and a very gentle feed. Any more than that risked stalling and a jam and release set it of ricking back and fore in a most disturbing way.
For the benefit of anyone as innocent as I, the cut is very much an interrupted cut on quite a large diameter (for a tiny lathe), so each rotation there is s significant change of load as it goes from not cutting to cutting. Poor lathe.
Still we've survived. Next is to drill out to as big as I can go (14mm I think) and then gently bore out another 36 mm - gently!.
So after a few weeks of distraction (and to be honest, the shed being far too cold to face), I've finally 'finished' the crankshaft.
All that's left is to pin the crank and the cut out the awkward bit of the shaft.
Drilling the pin holes (to 3.9mm)
The metal for the pins was source from a specialist retailer - B&Q! I have no idea what sort of steel it is.
However, before using them I performed extensive malleability. That is I hit the rods with a hammer and made short the dented and spread. Precision engineering at it's finest.
Which was carried through in the delicate insertion and fixing of said pins.
The 'anvil' was a small piece of inch plate sourced from a scrapyard. I wasn't terribly good at this bouncing around somewhat. Which (I'm claiming0 is why some of the pins bent and stuck and I had to push the other half in from the other side.
Curiously, I found that despite being assembled on a surface plate with some care and being glued good and proper the journals are not (any more?) totally in line (about 0.25mm out from one end to the other). I'm rather hoping that the shafts are in line!
Next cut out the middle bit
Tada! A Crankshaft.
Dennis, Jason. Thanks for the advice on the ER32. It would seem that my foray into engineering merely reveals an increasing vista of ignorance - soothed only by the knowledge and advice on this forum.
And thanks for the advice on drilling, Jason. Very obvious once you're told!
I have a 15mm blacksmith's drill on order.
The only thing that surprised me is the size of the starter drill. I would have thought that a 6mm would be quite slow and to get through the solid metal.
What sort of speed should I run this at? I tend to be cautious on speeds (fear and ignorance).
So it's month since my last post. My time has largely been taken up with work (ugh), a weeks skiing in France (cold) and a week with customers in Toronto (very cold).
I've also quit my job so will be a happily free man in a few weeks - though hopefully not for too long. If anyone wants a brilliant software designer/architect/manager type person then drop me an IM! (am I allowed to advertise, Neil?)
But back to the real world. I've got round to gluing the main shaft of the crankcase into the journals, but not yet drilled, reamed and bashed for pins, cut through the shaft and tidy up. This weekend probably.
Instead I've started work on the cylinder. The first thing was to make a boring bar to take an HSS bit. I've an indexed boring bar with a carbide bit, but experience has shown that it won't cut dead parallel when finishing off a cylinder.
This gave me a good excuse for buying a square Stevenson's block with an ER32 collet holder.
I have some 13mm rod which I cut and faced, set in the collet holder, stood on a couple of parallels and pushed against a bit of 10x20mm bar aligned with the table and against a set bolt to register it (you can't see that in any of the photos)
This is me squaring the end to fit in the tool holder. It's a terrible photo really!
Next find the edge with a wobbler. Which disintegrated in the process (the rod came out of the ball), but some locktite fixed that.
Centre drill to spot the hole for some 6mm hss bar, drill to about 4 mm then to 5.8.
you can see how the block is held and registered a bit better in this photo.
Turn the block through 90 degrees, centre drill and the drill through with a 4..4 mm for the M5 grub screw.
Finally, ream the bit hole to 6mm and tap the grub screw hole
And here's the finished product!
I don't think I've got a good profile on the bit, but that's easy enough to regrind..
The other thing I've started on is the cylinder.
Somehow a complex work of art must emerge from the dull envelope...
I started off by finding the best end (one end was quite flat and square, the other not so much) and squared the other end up in the mill.
I don't really know why I did it this way as it would have been quicker and easier in the lathe.
And then marked up to make sure that the cylinder actually fits in the er, cylinder and to find the centre for boring
Is this how Michelangelo felt when he first dragged his charcoal across the marble that would be David?
I've also invested in some long drills. It's all very well having a stiff boring bar, but you still need a hole to bore out from!
I've got a bunch of them from 2mm up to 10mm - does anyone have advice on the best size to start from? The chances of a 2mm drill getting through 85mm of cast iron seem remote, but I don't know how easily a big drill will go through.
Or am I approaching this the wrong way and should start with some other sort of drill?
|Thread: Alternative to a QCTP?|
I've recently replaced my aluminium QCTP (which is rubbish) for a steel one from ARC and I've found the improvement considerable. Parting has even become, if not pleasant, at least more or less doable.
However, I find I still use the aluminium one (it has a boring bar attachment I don't have for the arc one - though I'm making a boring bar which will fit the ARC).
I also have in mind to make a tool post which just does parting. Probably with a carbine insert. I call this FQCTP (Fairly Quick Change Tool Post) as swapping tool posts (even with spanners / hex keys and so on) is much quicker than any machine operations I do.
So I'm all for the Fairly Quick Change Tool Post and have registered the trademark accordingly! £1.50 for each mention in this forum, please...
|Thread: Getting started with gear cutting.|
Slightly (but not much) off topic, but has anyone used the cheap Chinese gear cutters found on eBay? There's a set of 8 advertised for about £37 which is roughly what you pay for one supplied in the UK. Other sets range up to £45 or so.
I don't expect them to be high precision and be able to cut steel for 20 years full time every day, but I would have hoped it would survive a few years of a hobbiest (who would probably only cut a few dozen years in that time).
|Thread: What Did You Do Today 2019|
There is no aspect of that instrument which is not 1,000,000 than on mine.
Mind you, then there's the player...
Most likely you can probably actually play the instrument whereas I.....
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