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Member postings for Iain Downs

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
20/09/2020 10:14:26

I was rather dreading this bit. Boring out the strap, which requires a fair amount of precision on all sides. I still think that the accuracy was more luck than judgement - but who's complaining?

The first thing I did was to skim up the faces of the joint of the strap. I'm blaming the mount in the vice which didn't provide enough support, but the two pieces weren't straight when bolted together. This was just the lightest skim, though I fear that the centre line is no longer quite on centre.

Having done that I bolted each half together in the vice (to make sure the two halves were dead in line and clamped it in the vice on parallels. I dithered about this, wondering if I should put some kind of support under the centre line, but in the end did not and there was no drama.

First task was to centre the item (edge finder and the half option on the DRO - I STILL love my DRO!).

Then to drill. I started off with a 4mm stub drill then up to 6, 8, 10 and 12mm. I also love stub drills (thank you Model Engineer forum for my training!).. Then a14mm blacksmiths and a 20 mm blacksmiths. Again no drama.

eccentric strap 07.jpg

Now it was time for the boring head. My mistake here was not to lock the Y axis (I'd locked the X but for some reason not the Y) and the table had drifted a little. Were it not for the DRO, I would neither have noticed nor being able to fix it (did I mention how much I like my DRO?). I simply put the Y back to zero and locked it. Naughty Iain.

eccentric strap 08.jpg

I was a bit concerned about how to measure the groove depth and width. I could get the depth right by using the quill DRO, but the width required a measurement which was blocked by the boring head. DRO to the rescue! (Are you getting a theme here!). I zeroed the Y DRO and locked. Then zeroed the quill DRO as it touched the surface. Thus I could move the head out of the way and get it exactly back where it belonged afterwards. Not quite that simple as locking the Z moved the head a couple of thou, but that wasn't to hard to work round.

eccentric strap 09.jpg

Everything seemed to work well in that the try fit of the eccentric worked, but when I tried to assemble the whole lot it just didn't' fit. :sad

After a moments thought it occurred to me that there was probably a small radius on the boring bar, but the eccentric edge was quite sharp. So I had a bit of a go on the eccentric with a smooth file and the strap with a pointed scraper.

Nearly! but not quite. Close though. Finally, I got some 7 (microns I think?) diamond paste, assembled it, added a dummy crankshaft and give it a bit of a lapping.

eccentric strap 10.jpg

Some turns with the bolts tightened a bit every few turns and the eccentric is running smoothly in the strap! Cleaned off with WD40 and job done (for now).

I'm hoping my luck holds for the next piece this afternoon (if all goes well), then I all I have to worry about is how to mill the outside round.

Iain

11/09/2020 12:12:04

I've started work on the straps and this is my plan.

First make some blanks, 66x60x8mm.

Cut out shoulders for bolting the two halves of each strap together, drill and tap.

Slit the two halves apart.

Bolt together, drill and bore ( on the mill) the centre and then the flanges.

Mount on a rotary table and take away the bits I don't want.

Phew! sounds easy?

So I started with a largish piece of steel - 200mm x 100 x 10 and trimmed it down on the mill.

eccentric strap 01.jpg

First step was to get the edges reasonably straight so I had something hold for the surfacing.

then to reduce it to 8mm. This wen pretty well. I ended up with it with 0.04 mm across the whole area, most of the error being due to a hump in the centre. This in turn probably due to using 80mm parallels on a 200mm work piece. I've longer parallels on order.

Next to take it down in height and trim the edges now I had some nice clean surfaces to work from.

To the bandsaw and off come my two prospective straps,then trimmed to exact width on the mill.

Marked up on the surface plate as a check, but then back to the mill to use the DRO to mark and drlll some nice round corners for edge relief.

eccentric strap 02.jpg

eccentric strap 03.jpg

The stop was used so that I only need to edge find once. The two pieces being within 0.01 / 0.02 in all dimensions (somewhat to my shock).

Then flip the straps on their end and carve out the unwanted bits. I had to do a bit of cleaning up the relief with a small file, but you won't tell anyone will you?

eccentric strap 04.jpg

Back to the mill to be drilled and tapped.

eccentric strap 05.jpg

The lovely DRO let me spot, drill, tap drill and tap without having to change tools a million times. Thanks, DRO!

I've used my Father's day letter punches to mark which bit belongs to which so I don't get them mixed up after slitting.

eccentric strap 06.jpg

That's it for now. Next step is to bolt them together (may also superglue) get them back in the mill, drill and bore.

Again the DRO will help here as I can wind the Head up out of the way to measure and be sure to get it back to where it was so I have a nice clean depth of cut!

Iain

Thread: What Did You Do Today 2020
11/09/2020 11:43:58

I've been fed up with the lighting in my shed even after I swapped out the florescent tubes for LED tubes. The shed is a fairly standard 8x16 garage with one window along the left wall (as you walk in). At the top of that wall are 2 90cm tubes and in the centre of the peak is another one.

The mill is at the bottom on the left and the lathe on the right. Neither get natural light.

Dull!

After looking at various options, I found some LED strips on ebay. I believe I'm no longer allowed to put links in, but the ones I found (16ft 2835 SMD strips) were from USA and cost around a tenner with 3 or 4 quid postage. I ended up buying two (well, who wouldn't?) for around 25 quid.

I cut down one strip as follows. in the centre at the end, I put up two strips (150 cm each) - they come with sticky backs which have stuck to the rafters really well. At the front, I put up one strip and drove all three from one of the many power supplies that decades of buying computers and other electronics has left lying around (there, SWMBO, I said they'd come in useful sometime!).

Wired up to the main light switch and the difference is truly remarkable.. It's close to being daylight bright. Brighter for most days in blighty, I would say!

workshop lights 2.jpg

The one in the middle is the LED tube one, nearest are the two strips at the far end is the single strip.. You can see the power supply (black, of course) on top of the rafter at the far end.

In case you're wondering, My workshop is not on a ship, in high seas. I'm just a rubbish photographer.!

I also have half a meter of the stuff left, which is being re-purposed into a mill light to be mounted under the head.

Strongly recommended - the whole let is cheaper than one new tube at a fraction of the brightness.

Iain

Thread: Mill Tip
29/08/2020 12:19:13

I had a go at this with a reasonably small piece and it seemed to work quite well. I shall be using this in future!

Iain

Thread: Microstepping
29/08/2020 12:16:17

This is a very useful post. I was planning on doing some experimentation with microstepping once I've finished my controller software (don't ask, I'm currently trying to implement a windowing system on an arduino after a number of architectural false starts).

I did think about changing the number of microsteps from the ardiuno, but I have one of those TB6600 type drivers in it's own box and fancy neither opening it up, nor using some actualtors to flip the dip switches wink)

Iain

Thread: Is a hand scraper pulled or pushed?
23/08/2020 16:34:34

IanT said he couldn't find Sandvik scraper blades. I found some here **LINK** which I think are the right ones.

Iain

22/08/2020 08:36:47

There are a lot of videos on youtube about scraping. Stefan Gotteswinter has some good ones and there is an excellent one from the war period which is referenced somewhere on this forum (I think I posted the link at some point).

Personally, I've done some scraping, but the results are mixed. I've had some success in scraping in bearings, but properly flat surfaces still elude me, though I've been able to 'improve' my micro mill no end. (not saying much).

Iain

Thread: Do you clean the workshop up every day?
22/08/2020 08:31:33

I clean the mill (and floor) fairly often as it collects a lot of swarf. Similarly the lathe and table if there's a lot of swarf. But this is usually at the start of a session. After a session, I'm either elated that something has gone right (well occasionally) in which case who wants to clear up? Or depressed because I've measure several times and still cut wrong. In which case I just want to go and sulk.

One of the triggers is when it's uncomfortable walking on the floor because of the swarf. This has been a much bigger problem since my mill went from 20 kG of fierceness to 240kG!

Iain

Thread: Hardware for the shop
22/08/2020 08:25:44

When I need a particular bolt, I buy a kit (usually from Amazon) which has a selection. For example, I've just (literally just!) placed an order for a set of M3/M4/M5 countersunk allen key bolts in various sizes. I only need 7 of them, but buying 10 would cost me (say) a fiver and buying a selection which contains 400 will cost me 15 quid.

One thing I dislike is my inability to buy individual drills at a reasonable price. If I want a (say) 9.7 as a pre-drill before a reamer, then I appear to have to buy 5 or 10 of them. It's cheap enough, but one drill will probably last me the rest of my life (especially if I ever get my drill sharpener in use and running). I resent having to buy 4 spares.

grrr.

Iain

Thread: Steam Engine Number One
16/08/2020 14:50:51

Jason - thanks for the advice and link. I've since reviewed some you tube and have a feeling about how to make them. The steel is on order.

Nigel - again, thanks. I confess that I'm building this engine to build it and not with a specific application in mind. The original design criteria was something that would run my lathe. Since then I've thought of a steam powered go-kart and, yes a marine engine.

Frankly I will delighted if it just runs at all!

Off out now to do a bit of work on the crosshead guide.

Iain

13/08/2020 20:43:17

A couple of weeks later and the eccentrics are done! For the main part this has gone better than I expected which is pleasing.

In the previous post, I ended up with a round 40mm cast iron bar held securely in the 4 jaw. The first task was to put 4mm groves in for the straps. FIrst step with this was to grind a tool, more or less a parting off tool, but a bit under 4mm. Then to make the 2mm deep grooves.

eccentric 06 grooving.jpg

A bit of chatter on this, but this was cleaned up when I slid the tool sideways to open the slot out to 4mm.

Next step was to offset the bar by 6mm. This went surprisingly well, using the 2 key approach.

eccentric 07 moving.jpg

next step was to turn the collar on the end

eccentric 07-5 turning the stub.jpg

Then came the nasty bit.

I needed to part off the first eccentric. If I thought parting off was a challenge, let's try it on an interrupted cut!

The was very very slow going, feeding the tool in very gently to try and prevent a jam. For some reason I decided to use the 4mm tool to get most of the way down and then 'finish off' with a 2mm parting tool.

At this point, disaster struck! There was a solid jam, the lights went out,, flashes came from inside the lathe electrics and everything stopped.

I'd blown one of the sets of breakers in the house. I took this as a message - it was about 9 o'clock (a self imposed deadline to stop the neighbours getting irate) and clearly time to stop.

The next half hour or so was spent resetting the RCD, rebooting PCs and fixing networking issues. In fact I was still struggling with connect problems when I started work the today!

So tonight I went back out to the shed, thoughts of fried thyristors uppermost in my mind. But to my surprise (and relief) the lathe started up straight away - I hadn't even blown the lathe fuse...

Back on to the parting off

eccentric 08 parting off.jpg

eccentric 09 first one.jpg

Eventually, this was done and I set about the second eccentric.

This time I decided that parting off this type of thing was NOT my idea of fun, so I took the piece out of the chuck and cut it off on the band saw. This was both immeasurably quicker and a great deal less stressfull.

Swapped the chuck for a 3 jaw and popped the piece back in to clean off the back.

eccentric 10 trimming the back.jpg

Next step was to pop them into the milling vice and drill and tap an M4 hole for a grub screw and here we are!

eccentric 11 done.jpg

Most likely, the next work item are the eccentric straps. To be honest, I've not yet worked out how to machine these. I've seen that there are videos on youtube and no doubt advice in this august forum, but I've not got round to looking.

I was wondering if I should make the straps in steel or brass. I was thinking steel, but brass would like nice, wouldn't it? Any reason why not?

What I may do before that (if I have to wait for material, for example) is to mount the cross head guide,

I can feel it getting close!

Iain

01/08/2020 20:45:17

And finally some work on the eccentric!

First I drilled a centre in end of the bar, holding it with the 4 jaw on the (aforementioned) chuck holding plate

eccentric 01 centre drill.jpg

Then onto the lathe with a 3 jaw lightly nipped and the end of the bar in a centre

eccentric 02 skim.jpg

First few passes with a carbide insert which didn't really work too well - perhaps I wasn't taking enough off, it seemed to rub rather than cut - though the dust that's produced was hot enough.

Then finished with a nice traditional HSS tool. This reduced the 50mm bar to about 48mm - I wasn't trying for a particular size - just to get it nice and clean to hold in the 4 jaw.

Off the lathe and onto the bandsaw to cut a bit over 70mm off. This operation surprised me as the bandsaw went through the bar like it was butter. This in contrast with the hour it took to cut a (granted much bigger) aluminium bar. I see a blade with fewer teeth in my future before I cut more big ally!

eccentric 03 face ends.jpg

Faced off both ends. This time with the same carbide tool which didn't do well on the outside. Worked fine for facing!

Then onto the mill for the squaring

eccentric 04 square end.jpg

Again, the DRO made this child's play. I used an edge finder to get the Y edge and zeroed the DRO, then the same with the X. Then moved the table to center the spindle over the centre of the bar and zeroed X&Y.

Oh - and I discovered why I got a 4 Axis DRO! At the time it was just because I could but didn't really know what I would do with it. After all the Spindle DRO would do all I wanted.. However, I realised here that I could use the Z to take the head down by 25mm with the spindle high and fully locked. In theory more rigidity! I'm not 100% sure this will make a difference in practise, but it certainly makes me feel better about the extra spend...

eccentric 05 centre.jpg

This is as far as I got today. There's the piece in the 4 jaw waiting to be indicated and the indicator mounted on the QCTP with the mounting bracket I made.

Frankly, I have yet to master (or even get close) to centring in the 4 jaw, so I was as pleased to leave it for another day...

Iain

01/08/2020 20:31:51

This phase of the operation shows that you often spend more time making the tools to make the parts than you do making the parts. Not that making the tools isn't as much if not more fun, but ...

In this case, I've given some thought as to how to machine the eccentrics and I've come up with an approach that looks like this.

eccentrics build plan.jpg

So the idea is to mill a square on the end of the cast iron bar to hold it in the 4 jaw. Then moving the piece to between the eccentrics and the offset of the crank will be (relativel)y easy. I worried about how to hold the piece on the mill (a round shaft vertical) and quickly decided a chuck was the right way. So how to hold the chuck? I chuck holding plate, of course!

I have some pieces of 6 inch square x 1 inch plate I bought many years ago for a first project which was going to be a lathe. Ah, Hubris! Downfall of the Gods and amateur engineers who over-reach. So the headstock sides have been re-purposed since for more practical uses.

First, to square the sawn ends so I could put it in the vice

mill chuck mount 01.jpg

Then, for the first time, used the versatility of this ARC versatile vice. You can move the jaws around to hold bigger pieces - the standard jaws won''t hold a 6 inch piece.

mill chuck mount 02.jpg

This worked really well and I was able to get a nice shiny flat plate.

Now here's the exciting part. My first attempt to use the PCD function on the DRO.

mill chuck mount 03.jpg

Set the centre of the plate up with the co-axial indicator and set the INC register on the DRO to zero. I have to say the DRO seems pretty good (but see later) but the chinglese manual is not the best. Once I zero'd I set the PCD to 84mm diameter, 5 holes (yes, for some reason you have to end up where you started, so drilling 4 holes means you have to enter '5' and start at 0 degrees.

mill chuck mount 04.jpg

Oh! I've just discovered you can set the picture size!!!

Anyway running through the holes is pretty easy, you just press <- and then wind the handles till X & Y are zero. The DRO really is transformational - in another tool to make the eccentric, I had to spot, drill and tap three holes. Before, I would have spotted, swapped to the drill, drilled, switch to the tap, tapped (manually) and then did this twice more. With the DRO, I set register 0 to 0, spotted, moved to the next position, set register 1 to 0, spotted, moved to the next, set register 2, spotted. Changed drill, drilled, selected register 2, drilled and so on. Much less swapping of tools!. On this piece I also managed to power tap successfully for the first time.

Anyway, here's what the Chuck holding plate looks like

mill chuck mount 06.jpg

I ended up making it suitable for 3 and 4 jaws as you can see.

And here with a chuck on it

mill chuck mount 07.jpg

The other tool I mentioned above was something to hold my indicator in the QCTP - just a piece of mild with some bolt holes to hold the indicator. When I've tried to centre in the 4 jaw in the past I've used a lever type indicator with a very small degree of movement. It's to easy for an idiot like me to back the piece out of the range of movement of this - if I can get it in in the first place, so I'm hoping that this will make things easier.

The one peculiar thing (well something that went wrong, which is not that peculiar for me!) is that the chucks didn't quite fit. When I measured the diameter between the holes (and added 8mm to get to the centre), it came to a tiny amount less than 84mm. The fix was easy - just drill out to 8.5mm. I will do some tests on this later and see if I can work out what I've screwed up!

Next is preparing the piece for the eccentric.

27/07/2020 19:52:39

Wow. 2 months + since I last posted. In the meantime I've been installing DRO and Power feed on my mill, but I've finally got back to my engine.

The task was to re-do the bottom cylinder plate which I'd manage to machine the spigot off-centre to the central hole (no I can't imagine how, either).

I started off by trying to use a superglue chuck. The chuck was snug to the chuck plate with a 6mm hole in the centre. The plate has a 6mm hole in the centre and I located them with some 6mm round toolbit material.

When I put them together on the lathe I noticed that central hole didn't seem central. So I got my indicator out and it seemed to be 0.5 mm off. Which I thought was too much.

bottomcylinderplate2 on superglue chuck.jpg

Actually, I then spent quite some time (whilst working on other projects) trying to work out how to hold the plate.

IN the end, I drilled and tapped two M6 holes on the outside edge and mounted it on my face plate.

A bit of tapping and I got it reasonably centred (0.02/0.03 mm)

bottom plate 2 centering.jpg

Next a rough cut to get 2mm down through the area which had an interrupted cut. I have interrupted cuts. I have to run the lathe at a higher speed than I feel comfortable with or it stalls.And sometimes it sticks or stalls anyway.

bottom plate 2 first cut.jpg

Then it was taking the rest down to a 50mm diameter and boring a 20mm hole in the centre. All very gingerly and trying and fitting with the cylinder and piston gland.

bottom plate 2 and one.jpg

Here we contrast the new one and the original (bad) one. this time as you see I've done the bits where the registration matters before the cosmetics.

And, guess what? It all fits together!

bottom plate 2 assembled.jpg

Next I needed to prepare the fixings for the cylinder. This is where my new DRO gave me a great deal of happiness.

First was to clamp the cylinder to the plate and use some slip gauges to make sure the valve face was parallel to the back of the cylinder plate (this by getting a close approximation and 'feeling' - This is not something where the odd 0.05 mm will make a lot of difference) then to clamp the cylinder in the vice.

bottom plate 2 preparing for mounting holes.jpg

Although the DRO has something to make holes round a circle, I'd designed this to have a slightly wider gap on the port side of the cylinder. In hindsight not sure if this was required to clear the ports, but there you are. I took my design and made a drawing with the offsets of all the holes from the centre of the plate marked and used that work out the positions on the DRO

bottom plate 2 i love my dro.jpg

I first put 7 spots in with a 5mm Spotting drill , then changed to a tap drill and put 7 tapping holes in, then back to the spotting drill to go just down through the 7.5mm plate (I should have done this to start with and saved a step), then a countersink for the 7 holes and finally, swapped out to a tap.

bottom plate 2 tapping cylinder.jpg

Doing this with the DRO was a joy. The top end I did on a rotary table with swapping between, drills, taps and drills for each hole!

bottom plate 2 drilled and countered.jpg

Here we go! Already for mounting!

Next step is the eccentrics. I might also want to rethink some of the decoration of this plate (rounded corners and so on) to better fit with the reversing gear.

It's nice to have some progress!

Iain

Thread: Power feed for a VM32L mill
27/07/2020 19:24:37

At last! It's done! Well... nearly

motor drive 24 in place01.jpg

motor drive 25 in place02.jpg

I've run this up with my test program and can get about 8mm/sec with 8x microstepping. I'm planning to try lower levels of microstepping and check how that affects quality and performance.

Now, I say it's done, but I'm lying. My control program is still being worked on. I decided after some red herrings to put the UI for the control on an Arduino, so I'm working on that at the moment.

Also I want to have end stops working before I use it in anger and that needs a bit more metalwork and electronics - and software.

In the meantime it's back to my vertical engine (at LONG last).

Iain

When that's done, I will do som

Thread: Non tilting; tilting head.....tilt
27/07/2020 19:12:46

Thanks, all.

I loosened things up and have got a reasonable tram. I had some challenges to start with with wandering values, but found that this was just the mount wasn't tight enough.

I can't quite believe it but I appear to have got the spindle square to with 0.01mm over a span of 220mm.

Some of the problems I raised about alignment in a previous post appear to be resolved. When I centre with my coaxial centre and then switch to a chuck, the drill is spot on the centre.

Iain

Thread: Magnetised digital calipers
26/07/2020 12:40:58

Curiously, I just bought a magnetiser / demagnetiser from Aldi for £2.99 (I mean, why not?).

It has 2 holes and you pull a screwdriver through one to magnetise it and the other to demagnetise it.

It *seems* to work - at least on an old phillips screwdriver. I've no idea how.

It won't do for calipers mind you - the hole's too small.

Iain

Thread: Non tilting; tilting head.....tilt
22/07/2020 18:36:47

HI, Shent.

I'm actually not looking to rotate the head (by more than 1 degree, anyway).

Not sure what you mean by the various bolts. There's a centre bolt and 3 at 120 degrees with one at the bottom. I've loosened the (3) outside bolts and can't move anything. I'm wondering if I need to unlock the centre bolt though Jason's manual doesn't say so.

Iain

Thread: Induction Hob problem
22/07/2020 17:31:25

Thanks all. I've not tried the turning it on and off again (at least not recently) but you would think I'd no about that as an IT bloke.

I have had a look on ebay and it looks like it's either easy (apart from pulling the oven and hob out) or expensive. To the point of buy a new hob...

Iain

Thread: Is a drip feed coolant advisable
22/07/2020 17:29:33

This is a bit of a side track, but vaguely related.

I use CT90 spray for cutting oil. No science, just what screwfix sell.

Recently, I bought a can off eBay, not having read the word 'foaming' - or at least not thinking about it.

It came, I squirted. It's like shaving foam! You can't see the cut! What's the purpose of this?

And despite my nationality (God's Country), I confess I'm strongly inclined to deep six it and by some transparent stuff.

Iain

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