Member postings for Iain Downs

Sorry, Ady - I'm afraid I don't get what you're saying...

Iain

My slitting saws have seen very little use. the one I ended up using here has at most been used 2 or 3 times before. My original practice attempts (on an uncut 20mm bar) were disastrous. this due to my two 0.5mm blades being distinctly wavy. The latest attempt used a 1mm think 80mm 100 tooth saw.

I've also seen quite a bit of both lateral and angular run out. my best attempts are seeing something like 0.02mm at 12mm (vertical deviation) from the centre of the arbour (where the saw sits) and thus 0.15mm or more at the blade end. Not sure if this is adding to the issue or if this is reasonable for hobby kit.

I note that both of Jason's attempts have some curl, though he's certainly doing better than me!

Any suggestions welcome, of course.

Iain

I've tried your method, Jason, and have made some progress.

Essentially, set up is as above, but with a 20mm silver steel bar in a (new chinese) toolmakers vice on the rotary table. And all manual...

Broadly, this worked well, but when I came to cut off the hand, the hand curled up like a little snail. In earlier messing around on the whole bar I found I could reduce this buy keeping it cool and taking it slow. Not so with this little hand.

It's not really uncurlable to dead flat (at least I don't know how). Uncurling results in a rather lumpy affair. My next attempt will probably include placing some kind of fixture on top of it to keep it in place, though I'm not entirely clear, yet, on how that will work.

For those who were interested in my waterworks (the stop tap variety), in the end this proved rather simple and actually took less time and made less mess than I expected, which as my wife will tell you is very unusual!

Getting closer!

Iain

I like the idea of a subplate, though it's not something I can do right at the moment.

Sadly, the indications are engraved in the table top and can't be moved relative to it. If I align the T slots X-Y, the 0 degree marker disappears under the table clamp!

Iain

Joe Pie rather neatly puts X and & reference bars on his rotary table so he can accurately move the part around (adjustable parallels and stuff) and that seems like a good idea.

However, his table has six T slots which makes bolting the reference bars down fairly easy. Mine has four and the slots in no way line up with X and Y on the mill. This appears to be by design, though I have no idea why...

What I thought I could do is to drill and tap a set of M6 holes, effectively making the top of the table into a fixture plate. Possibly also ream for some pins to set X and Y accurately.

The table is an 8 inch and I think the top is probably between 15 and 20mm deep. There are some accurate keys underneath the table so I can be sure of always setting it down accurately on the mill.

Are there any reasons why this is a bad idea or any suggestions for a better approach?

Iain

Andy - the runouts do seem to vary quite a bit, though I found the worst part is generally the collet nut (some of which are unusable. Some are quite good and I have collets which claim to be decent.

the point of my design is to put it in a collet in a (locked) mill spindle -not much chance of driving that from behind!

Iain

Just wanted to say thankyou for the useful comments.

My own use case is to put the spindle cartridge in the spindle of my mill and drive the (high speed) spindle from a motor hanging off the cartridge.

The drawing below my give an idea.

Left is the spindle (cheap Chinese ER11 'extension rod' which runs in a 'cartridge' (some imagination is required to see the bottom part as an ER11 collet and above that a timing pulley). Attached to the bottom of the cartridge is a bracket that holds the motor (in my case a 200W Chinese thing). Again imagine the timing belt between the two,

The spindle is supported on bearings at the top and bottom of the cartridge, loctited in. I've also made a version with preload applied by nut with a thread on the top of the HS spindle (cuts fine with single point threading) though that performed somewhat worse than the one which was just glued.

The specific thing I wanted to achieve is to be able to mount the high speed spindle in the mill and have it be correctly registered. I could, for example rough something out with a 10mm end mill and tidy up with a 1mm mill.

This kind of works ( drilling with sub 1mm drills is entirely possible now), but the run out is bigger than I'd like. I'm not sure if all the complications of Steve's spindle is really required for what I want. In particular, going mad for rigidity may make little sense if I have a bit sticking out with a drive on it!

I'd be interested in any suggestions or comments before I build my next prototype.

Iain

The spindle mainly - it's quite complicated!

Iain

I'm particularly interested in how you plan to machine the spindle, Steve. It looks to me like a challenging level of precision for a mini-lathe. Certainly beyond what I think I could achieve.

When you get back to your drawing board, perhaps you could sketch out your approach!

Iain

I'm very interested in this thread as I've been in the process of building a similar type of spindle, but somewhat more naively.

In my approach, I only have one bearing at each end and I'm interested in what sort of issues this is likely to cause. In one design (I'm trying several!), I have the bearings loctited in each end, a loctited washer to act as a stop at the collet end and a nut to apply preload.

I'm using various chinese components, especially for the spindle proper (extension rods they call them), which I don't believe I can produce to anything like the needed accuracy.

I look forward to hearing how it goes!

Iain

Sometimes you just need to know the right name for something. Thanks to all - borosilicate 3D was the trick.

I was hung up on the originals being mirror finished...

Iain

Hi, all.

After a recent tussle with my printer I am in need of a replacement bed.

The tussle involved the heater and thermostat popping out of the hot end, falling on the print in progress and proceeding to melt what was already printed in some kind of manic thermal runaway. The plastic was really hard to remove and I broke the tile in the process.

What I need is a 200mm x 200mmx4mm glass mirror tile. I have been unable to find something of that size in glass, though I'm sure they were available a couple of years back.

If anyone can suggest a source (or an alternate), I would be very grateful.

The printer is originally from Factory3D but Mike who is normally very helpful seems to be out of action at the moment,

Iain

That's brilliant, Jason.

Mind you one of my earlier attempts was simply to slice off a 0.25mm sliver from a piece of silver steel. It failed miserably - the saw ran up into the top surface almost immediately. So I abandoned that idea, clearly too early.

I shall have another go. However, today is going to be about replacing the water stop tap as it comes into the house (in a most awkward position) as it has sprung a tiny little leak. Last time I had a problem it was due the installer not tightening the connections up properly and it spent some weeks or months dripping into one of my servers until the motherboard rusted! Obsolete board, (obsolete) hardware RAID 5. It took me a week just to reconstitute the hard drives (not to mention the cost). Not that much damage this time, but I can see interesting times ahead

Iain

Well, I'm getting a bit closer to my objective (though no longer 'high speed milling'.

The latest attempt used an HSS 2 flute 4mm cutter at 2200 rpm, superglue, but this time to a flat fixture (no grooves) and a lighter DOC (0.10 / 0.15mm).

The result is this

The thickness has gone quite well (within about 0.02mm of 0.24mm across the part) and the pipe has come out better than expected.

However, the width has not done so well, being off centre (ignore the obvious gouge at the bottom left - I turned the handle the wrong way, you think I'd learn after a decade or so of playing with these things). It's possible that I was a bit too aggressive in the trimming, or that one side was climb and one normal.

The part has lifted off the fixture, but not until the trimming / drilling. the drilling certainly lifted the part as the drill broke through. I think I can fix that by having a clamp with a 3mm hole applied before the drilling.

I might have another try with smaller cuts for the trimming and a consistent direction of cut. Failing that cut to an outline and finish with piercing saw and files.

Iain

The results of my test were not encouraging. I had bolted the raw material (roughly 30x8x1 mm) down to an aluminium fixture at each end with M3 bolts. Also with superglue underneath.

I took 0.25mm cuts with a 4mm carbide cutter at 2200rpm, thinning it down to 0.25 mm apart from a 3mm dia boss where the pivot will go (watch hand remember). Then trimmed down the sides to give a 2mm wide hand.

By the time I'd finished the trimming, the metal had lifted off the fixture (though still bolted down). I suspect that this actually happened on the thinning, not the trimming, but hard to tell with burs and suchlike.

I noted that the superglue tends to stick to the aluminium fixture and not the carbon steel material. The material has been polished flat (down to 2000 grit) and I wonder if I should score it up a bit more.

Experiments to try include less aggressive depth of cut, roughing up the surface of the steel or trying an HSS cutter and/or retrying the smaller cutters when I've improved the runout. Would shellac be a better choice?

Or anything else that you guys can suggest!

Iain

Thanks Vic.

My last attempt (with superglue and a 4mm cutter per Jason) failed. Sping! went the part.

I'm now looking at adding some bolt downs on the piece (also per Jason). After thinking about using the centre hole as a securing point, I've decided not to as it (probably) wouldn't end up exactly centred on the bore and tolerances are tight.

Instead, I will extend the piece and bolt both ends, leaving enough clearance for the cutter (I'm going to try most of it with a 4mm and finish off with a 1mm). Oh and superglue as well. I'm nervous about using shellec (though I have some) as I would imagine that the layer of stick would be thicker than superglue and not flat. Also not sure if it would stick better than superglue.

I've re-measured the run out of my current spindle. Depending on the collet (cheap from china and AA purchased recently) and the test bar, I get unacceptable levels. 0.06mm for example near the collect and over .12 at 20mm or so.

The bearings in the spindle are current 'budget' and I've ordered some ABEC-9 ones from China. I'm trying to find some more accurate 8mm straight shank ER11 spindles (extension bars they are called), but all I can find are 0.008 mm ones. I'm unclear how this is measured - Aliexpress is NOT good at technical detail for the main part!

.005 and .003 spindles start at 10mm shanks and that won't work with my design without reworking everything (and spending more money). If anyone knows a source I would be grateful.

So the test today (if all goes well) will be with the straight mill at 2200 rpm. See how it goes!

Iain

Thanks to all for useful (and occasionally entertaining) replies.

Currently, I have a (cheap) fitness watch so I can check the time, but it's been many years since I wore a real wristwatch and the habit has left me. There's less of an effort to look up at a clock than turn the wrist and tap on the modern thing. especially wearing an overall which hides it!

I suspect that the mechanism in an expensive analogue wall clock (atomic and radio apart) is quite likely to be the same as that in the cheapest. The price appears to be dependent on garnishing not functionality. I may be wrong, but have no interest in spending 50 quid and more to find the same issue.

I am firstly, not disciplined enough to wind up a mechanical clock reliably and secondly I am not necessarily in the shed consistently enough to make this a reliable form of timekeeping. Sadly - it would be more in keeping with my interests. Though I do have a clock on my todo list, it's some way off.

I think my solution is going to be to buy a mains powered digital wall clock like this or this. No moving parts, good visibility and should be accurate and reasonably resistant to shed vapours (the clock is high up and unlikely to get spilled on or splashed). I'm slightly favouring the one with the thermometer as I like to know how much I'm suffering in Summer and Winter!

Probably won't be buying this till later in the month as I have grossly overspent the shed budget already and will be in trouble from the boss....

Thanks again

Iain

Hi, All.

In my workshop I have a clock which tells me when I should go in and make the tea.

Sadly, it and it's predecessors just don't want to keep up with the modern world - which is to say that fairly shortly after a new battery is installed (say 2 - 3 months) it starts to slow down.

This seems to happen consistently - I'm on my 3rd clock now and have run through many batteries.

Clocks INSIDE the house seem to have no such trouble keeping up and the batteries last ages..

Not all clocks are the same, but all are bought on a lowest price basis from Amazon and I expect share pretty much the same mechanism.

For a while I thought this was mainly a cold weather phenomenon, but I'm having the same trouble in the current warmness.

Any ideas how I can (cheaply) find a reliable way of telling the time in the shed?

Thanks

Iain

HI, John.

I'm using Carbon steel from Cousins. It's available in sizes from 0.8mm and up. Carbon steel of course so it can be hardened and blues.

The actual hand is around 2mm across and 13 or so mm long. the piece I milled was about 10x20 mm for exactly that reason.

Not entirely sure how you are milling pinions with a slot drill - would that not be an incorrect profile?

Cheers!

Iain

Anyway, it's nice to have a new toy to play with.

Iain