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|
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.....
My own attempt at a stringed instrument was an electric bass guitar built in metalwork (and woodwork) at school.
Unlike Neil's it was pretty shit. the neck was a piece of square steel tube with quadrant glued either side of it and the body made up of bits of wood with a plywood top.
It did work, though.
The only real value it has in my history is that the frets were spaced according to the first useful computer program I ever wrote, running on the York University Computer (which was near the school).
Which appears to have set the stage for the rest of my career!
|Thread: Woes of My Digimatic|
God! What a pile of geeks!
Simon - can I congratulate you on your addition of some art into this forum of nerds (and Phil for responding in kind)?
Anyone on this forum can face a bar in a lathe, but who can write a poem about it? Neil - perhaps we need a competition ?
P.S. Please note the nerd writing this post declined to attempt a poem in reply...
|Thread: What Did You Do Today 2019|
The next note tells me that they don't expect to get a replacement from the manufacturer and they have finally suggested a refund.Of course I've said yes....
Well, the outcome (nothing) was what I expected, but still worth a try..
I have a nice note from the vendor of the £12.80 gear cutting set explaining that the batch they got in was poor quality (yeah, right). They offered no options, so I asked when they would get a good batch in....
You never know - I might just get something if I keep on. At least a refund...
|Thread: Best material for a crankshaft?|
I claim no particular knowledge in this matter, but I've recently built a crankshaft and crankcase (well nearly finished) and have used silver steel for the crankshaft.
I've used silver steel is that this appeared to the most consistently used material in the online and printed matter that I've come across.
The reasons behind this appear to be a combination of more hardness than most steels, but still being easy to work with (which tool steel would not be).
It's very easy to buy on eBay from a variety of vendors. The rods I bought were around 1 thou under nominal size and within microns of the actual size from end to end.
I'm sure people who know will jump in with better reasons (or probably alternatives), but that's my 2.5 penn'orth.
|Thread: What Did You Do Today 2019|
I'm not sure this is quite tea room relevant, but I was looking at gear cutters on eBay today. It was one of my 'Christmas list' items that didn't quite make the stocking.
I have no particular project for gear cutters, but feel certain that I need some!
The reason I think this worth a post is that my search turned up this item on eBay which purports to offer a 1 - 8 set for £12.80 including postage. As the next cheapest is about £37.00 I expect this is a bad entry, but felt it couldn't be ignored! So i've shelled out my £12.80 and hope that it comes through.
You will no doubt sneer at the quality of Hong Kong exports, but to be perfectly honest, that would be reasonable value if I just use them as coasters!
|Thread: Steam Engine Number One|
The 30th and 31st were eventful on the Steam Engine front.
The first thing I attempted was to bring down the top of the bearing cap. To do this I thought I'd give the 17mm indexed face mill I bought a few years back and abandoned after it kept smashing the mill gears. Yes, I know it was the driver's fault not the tool!
Since then I have fettled the mill somewhat (and perhaps gained a little in experience), with the main improvement being an adjustment to mesh the gears better, after which (2 years ago) the gears stopped breaking. Maybe it wasn't entirely me after all...
The face mill worked really well. With some care I could take off 1.5mm in one pass, though it was too easy at that depth to overload the little motor and stall it.
The thing I did wrong was to clamp it badly in my vice and it shifted. Which gouged the piece and stalled it. Also it turned out broke a cog off the motor gear. The mill still ran, and I finished off the bearing caps.
I have a box of spare gears for the CMD10, bought when breaking them was a weekly occurrence. Yes, you guessed. All the gears needed - apart from the motor gear.
I downed tools for the day and settled in front of the PC to call up Ketan's site. Then I thought, 'I have a 3D printer'.
A few moments with Onshape and I have a gear which looked like it was about right - it wasn't but it only took 20 mins or so to print. Armed with experience I printed a mod 1.5 16 tooth 8mm thick gear with a 3mm keyway.
After a bit of fettling (an 8mm reamer and a broach I'd made earlier) to tune up the bore, I fitted it and it worked!
First use was to counterbore the bearing bolt hole (now the bolts have arrived. Not too stressful and it worked a charm.
Next was scraping the bearings. This seemed to go better than my attempts at scraping flat. I think that one of the bearings is a little large and I have trimmed the faces of the bearing caps to tighten up a little. For one reason or another the bores are not quite in line with the base of the cap so I was scraping out at an angle.
The shaft blued.
Not the best of photos, but it's hard enough to see with mark 1 eyeball.
This isn't the final scrape by the way. I expect I could do better - the bearing surface on one side is quite good (lots of small high spots) - on the other side less so. In place I've got a horizontal rattle of 0.01mm or so which I think is reasonable. No doubt they will bed down.
Next was to use a 10mm carbide end mill to widen the gap so the journals would actually fit (and the new bearing coped well with this at 2000 RPM).
Then it was 'call it a day'. I still need to glue the shaft, pin it and cut out the middle. However, I like to quite whilst I'm ahead - had I buggered something up it would have spoilt a decent couple of days of work!
I could of course, have completed this today, but I felt weary and a little unwell for no reason I can quite put my finger on. My wife claims it was the copious amounts of red wine in celebration of the year and (and, as it happens, my birthday), but that hardly seems likely to me...
With best wishes to you all for 2019
Another couple of days of progress.
Firstly, I wanted to skim the crankase top and bottom to get some registration surfaces. MInd you with my little mill (CMD10) there's a limit to how nice I can get it - my attempts in the past to use a fly cutter were fairly abortive though I should give it another go now I'm a little less clueless.
This is the top of the crankcase. I did the underside with a 4 flute 10mm HSS bit and this with a 3 flute 10mm carbide bit. The carbide works so much better even on a final skim of a few thou. What's interesting is that you can just about see the 'crop circles' getting steadily worst towards the top left. the bottom right has the gibs fully engaged and the top left only just hanging on - the effects on rigidity are clear.
Next up was to drill the bearings through
I'd left 3.3 mm pilot holes in the bottom of the bearings and the idea of this assembly was to drill through to the crankcase with the shaft as near central as possible and able to move freely.
Sadly, I discovered at this point that I'd mucked something up and the circular buffer bits (I have no idea what you call them) stick out a bit too far so that the journals won't fit. That's not a crisis - once I've mounted the bottom bearings permanently I'll just skim off a bit with my mill.
Here's is the work in progress with the bearings temporarily bolted to the crankcase.
As this stands the shaft is a little stiff but only slightly. It may ease up with some better bolts (the only ones I had have an angle on the head end which forces them into the centre of the hole, some cap heads or simliar may allow ab bit of movement. Of course I don't have any of the right length so will have to order some.
Once that's done the next task is to lap the shaft in place. I'm going to use this shaft (which will eventually be the real one (using parts of it which won't actually be in the bearings. The bearings are over sized by between 2 and 3 thou. Should I try and reduce this by slimming down the bearings and lapping or is that sort of OK?
Also, I need to put some kind of lubrication channel in I think. I was going to drill a 2mm hole through the top bearing. Should I turn a grove on the inside or will the oil get there just fine!
May be a bit of a break on this now - leave is almost over and I've a skiing trip coming up. Next major item is the cylinder which will be er, interesting.
So 10 days on and a mix of results to report.
As stated the plan was to slit the iron into 4, bore and break apart. Here's how far I've got.
I wanted the horizontal split to be exactly 20mm above my base. I set up the slitting saw using some precision 2 4 8 blocks as below
Of course the slitting saw would only get half way through so I needed to turn the iron round and saw from both sides
and here is the result.
The astute among you will spot that the saw cut wasn't perfect. In fact there was a definite angle on each side leading to two facing ridges, each at half the width. I thought I could lap them out with some wet and dry on the surface plate, but this was just not working (given that the effective shape was convex this should not have surprised me. I ended up scraping to the point where it no longer visibly rocked.
The next cut, I planned to mill flat afterwards and measured accordingly.
Now for the boring part (so to speak)
then boring with a home ground hss bar. I think for the cylinder I will need to make a more substantial boring bar - there's too much flex in this.
In the end though it's not too bad. It might be a thou or two over but I think it will be alright.
Initially, I thought I'd screwed things up with the bore not being straight with respect to the base and sides.
Having remeasured, I'm seeing a drop of about 2 thou from to back, but that's comparable to the taper on the bore. The bore isn't quite centred but I make sure to drill and mount with the shaft in place so it will be reasonably OK.
phew! I dd NOT want to start this bit again.
I got my real cast iron block yesterday and spent an hour cutting and squaring
I do like my Aldi cut-off saw! A precision instrument it is not, but it gets through big lumps of metal in no time. I'm working out how to use it to saw a bit of a 100mm cast iron round bar, which will need different clamping somehow.
The plan is to square up and, from a face end cut it 20mm up, then glue back together then cut 22mm out and re=glue. Finally trim the rest to size so I have two bearings hidden in the iron and bore out and finish.
May finish squaring and do some cutting tonight if all goes well.
|Thread: Optical Centre Punch any good?|
I've had en email from chester refunding my purchase and telling me that the device is no longer manufactured.
Which begs the question of how they managed to have it on their website for sale.
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