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: co-axial indicators|
I got one a year ago for Amadeal which was around 80 quid.
What I found was that, if there was significant run out, then you got inaccurate results. The run out in this case was due to the chuck provided with it. The fact that there is a lot of air makes this worse.
When used with well set up equipment it decently accurate and really quick to set up.
Having said that, I'm hoping that my Xmas will include an indicator holder that attaches to the spindle of the mill as used by Joe Pie (on You Tube). This won't be quite as quick to use, but on the other hand you appear to be able to use it without swapping collets / chucks so it may end up equally quick and possibly more accurate.
Both Machine DRO and ARC sell one and they are a good deal cheaper than an coaxial indicator.
|Thread: What Metal is this?|
ColinG (outside this post) had two recommendations:-
Don't piss around with metal you've no idea about. He's right. By the time I've broken a few more tools it would have been cheaper to buy a nice piece of cast. On the other hand I am learning things, albeit by getting things wrong.
Put the end mill in an ER32 collet. This has a lot more bits of metal touching the tool and so will reduce the risk of it being pulled out. It turns out that my R8 10mm collet is actually about 10.06 and the cutter is slack fit, so even less touching. I have tried this and the results so far are positive.
Now to work out how to tidy up the mess I've made so far.
Yesterday I too roughly 15mm off each side wiht a 50mmface mill as above (about 1.5mm deep cuts at 800rpm). This went really well with rather lovely golden chips coming off. I did have some tearing on the first side, but I'd been cutting dry. Side 2 I used cutting fluid and got a great finish.
Then it started to go wrong. Here's a drawing of what I'm attempting
The next item on the work list was to mill out the channels under the lugs at the back. 21mm deep and about 14 wide.
This was slow going. I assumed if I could cut 1.5mm off a 40mm surface, I could cut 3mm deep with a 10mm carbide mill. The result was a slot that tapered upwards as the cutter was pushed up into the collet, and the metal at the end turn pale gold.
I kept at it with smaller cuts and took the speed down from 2000 to 1400. At one point I noticed that the cutter was glowing red and took this as an indication that I was working it too hard and slowed down. The cutter was still being pushed up into the collet, regardless of how tight I'd clamped. That is until it decide to pull itself into the trough rather suddenly and stalling the mill (I think it managed to spin the tool in the collet first, but not so sure of that!
I got to the bottom size I'd aimed for and decided to move out. (about 0.5mm cut). this sometimes worked and sometimes dug the channel deeper. So I tried cutting higher up, with the aim of a( or several) clean up passes. The last one I tried on this pulled the cutter down about 5mm towards the end of the slot and took a bit out of the foot.
I have some latitude with the design of this so I can make the slot deeper or wide so I can clean up my mess. However, I still have the other side to cut and it's clear that I'm approaching this quite wrongly.
The only 2 thoughts I have are :-
1. to change the orientation and cut in from the side, leaving the lugs solid until the end.
2. Follow the example of Joe Pie and drill the material out first and then take a VERY fine finishing pass.
Any more educated ideas would be most welcome.
Oh I started off with a 4 flute mill, but noticed that it was a bit chipped so swapped out to a 2 flute mill which seemed a little happier (and I don't SEEM to have broken it yet).
|Thread: How the Fork can I do this?|
Having taken all the advice on board, I think I will attempt to buy a new wooden handle!
Many thanks all.
Edited By Iain Downs on 22/11/2020 16:22:31
It's quite big.
All of your comments about the sensibility of make a handle for this thing are entirely well taken.
However, if we only did things that were sensible, not one of us would follow this ever challenging hobby!
Actually, I quite fancy having a go at this, if I can. Not because it's a sensible present (which it really isn't), but I may learn a bit about ally welding (or work-arounds) and my little sister's (entirely false) view that I'm quite clever will be reinforced!
Edited By Iain Downs on 20/11/2020 18:22:10
My Sister emailed me recently and asked if I would make a handle for her garden fork. I said I'd have a look and she organised her friend to (socially distantly) drop it in my front yard.
I, of course, had in my mind a hand tool like a trowel and what's turned up is a particularly large 20cm x 60cm garden fork!
I'd thought that I could scrabble something together on my lathe, maybe 10 inches long or so.
However, my lathe does not have the capacity to process something 40mm across and perhaps 600mm long.
Apart from the obvious answers (buy one from Amazon, for example), does anyone have any ideas about how I could approach it?
I expect that making one would be more expensive and take (Much much much) longer than buying one, but it IS the thought that counts.
The fork end is about 40mm in external diameter and 36mm internal diameter with a mild taper towards the fork proper.
I sized a piece of solid ally (assuming I could find a way of turning it down) and this came to about 2KG in weight which I suspect is just too heavy for a handle. Tube would be better, but there is less scope for carving bits out. Just hat the thought that I could get a tube to match the OD and make an insert to fit the inside of the fork.. Hmm. more like this,please!
I have a mig welder and an argon bottle,but never attempted aluminum.
Be kind! And clever...
|Thread: What Metal is this?|
I've cut the other end of the piece in the 4 jaw using the Ally carbide insert, in steps of maybe 3 thou and it's turned out very nice again.
The limiting factor seems to be the power of the lathe. If I take much more off the lathe struggles (550W CJ018A type) and I don't want to put too much hurt on it.
Tomorrow (or possibly later) I will be trimming the sides on the mill - taking about 10 -12 mm off each side. This will be with a carbide insert face mill (steel inserts, could afford the ally as well) and it will be interesting to see how it goes. I will keep you posted.
Peak4. I got the first calculation wrong. It's a bit more dense (see 3rd post).
My feeling when machining it was 'sticky'.
When I cut it on the bandsaw (over an hour in bits!), something had slipped so it was not straight. I ended up milling the worst surface flat it it took decent cuts (1mm) with a 63mm indexable face mill. So I have some hopes for chopping it on the mill!
Ady, I don't suppose your scrappie was near Ripon?
I was kind of hoping it was unobtanium, I would then sell it and buy a real surface gauge... And a new Lathe
Diameter ~89mm (radius 4.45 cm), height 35.5mm (3.55cm), weight 1.7kg (1700gm)
volume = pi r squared h = 4.45*4.45*pi*3.55 = 221 cc (cm3)
1700/221 = 7.69 g/cm3 (sorry copied the first one wrong).
which according to Engineer's edge is in the range for stainless steel.
So a few years ago (before I new better) I picked up some random bits of metal from the local scrapyard.
One was a shiny round bar 100mm across and about 200mm long.
Messing with it, to see what I could do, I stuck it in my mini lathe and managed (idiocy) to catch the end with a tool at some speed.
It did in the plastic gears and replacing them and the strip down and rebuild blew the controller and damaged the spindle.
All is now well, I hasten to add - bigger transistors, new spindle and metal gears. I should say thankyou for the learning experience!
So it sat there being a paper weight until recently when I decided to make a surface gauge and it seemed like a good place to start from.
So I chopped 35 mm off and put it in the lathe to face and clean up.
The facing went OK with a carbide tool, however the outside struggled with carbide (several tools) and hss. Part of this was that it was a mildly interrupted cut, The lathe was stalling (various speeds but around 300 rpm - any lower and there's not the power).
Just about to give up I tried it with an insert for aluminum a few thou at a time and that has produced a brilliant finish.
I also passed the tool over the face. I was taking cuts of around 2 - 4 thou and getting very thin yellow (hot) stringy swarf. The finish passes being faster, perhaps 800rpm for the spring (is that the word?) passes.
The finish is phenomenal.
I'd like to know what it is. It hasn't a touch of rust, it is slightly magnetic (that is a magnet sticks to it). It has an apparent density of about 6.8gm/cc,
Which puts it as some kind of stainless steel?
The next step is to chop quite a lof of it out in the mill (carbide tools again) and I'm wondering if it's the sort of stainless that work-hardens and if I need to use any particular techniques?
Edited By Iain Downs on 19/11/2020 17:21:51
|Thread: Steam engine from scrap metal|
Welcome to the ranks of home brew engine bodgers!
(Steam Engine Number one. Some day it will be done. It may even run!)
|Thread: What Did You Do Today 2020|
A while ago I had a go at building a spindle handle / mandrel based in some ideas in Neil's excellent book.
It was a failure (I blame the workman, by the way Mr Editor, not the writer!).
So I thought I'd have another go. This was the basic idea. I think that the first attempt may have failed because the angle of the plug was too steep (and the machining probably too rough).
The main challenge with this was cutting the slots and the square on the other end.
To accomplish this, I build a little block which I could clamp the bar in and then set it up on my saw table (and later the mill). the picture below is entirely posed because I didn't have a camera when I did the real work.
The scrap just in front of the blade are some bits superglued together to provide some support for the work - or it would go all over the place!.
Here's the finished product
I've established that it fits in the spindle and I can get it locked up reasonably well with only finger pressure. Not yet used it in anger.
However, that's not quite the end of the story (he digresses).
As a beginner, parting off was a bit of a trial. In fact a disaster. Until I bought a decent Quick Change tool post from ARC with a parting tool holder. This went really well, even on steel.
For a while. I don't know quite when but it stopped working nicely and the last year or so parting off has been a truly delicate operation with a nasty combination of grazing dust off and horrid horrid dig ins which felt like the lathe was about to burst.
So for the puller (part triangle, God knows what to call it) with the angle at the end. Arghh! Cried I and pulled out a bit of HSS I'd ground a less than 1mm wide parting bit into ages ago.
all of a sudden, I could part off. The steel came twirling off like it was dancing! I grooved the part to make space of the taper and then parted through. It was lovely!
Since then I've bought a indexable parting tool (usual source!) and that works brilliantly!
I have no idea what specifically I have been doing wrong, but the obvious culprit is the parting blade which I have ground down myself (and reground and sharpened).
So I'm actually happier that I seem to be able to part again than that I've made a nice handle!
|Thread: What air compressor should I buy?|
I'm having a bit of a rethink. Yes I can get a compressor which is quiet and not too feeble (probably). But for the same or less I can get a much more powerful compressor which is noisy.
My concern is a) the neighbouts and b) my ears, but, I am unlikely to use it often or for continuous work. So with the odd blast of air to clean the mill the motor would rarely start.
If I want to run it continuously I could choose my time of day - and as is (half seriously suggested) above, I can always stick it in a box.
I'm a bit conflicted too as it occured to me that I could spend my (circa £200) Christmas present budget on a quiet compressor or an 8 inch rotary table. I currently have a 4 inch one which swamped my micro mill, but is not working at all well for my new bigger mill (Mainly the problem is clamping work. It turns alright but the bed's so small).
Finally, if I do get a compressor with the aim of occasional sandblasting would a wooden cabinet work or would it get eroded too quickly?
Thanks for the input, guys.
The KIEI one mentioned by Jason looks like a sweet spot. The noise is tolerable (I have neighbours and a wife who stresses).
The sandblasting type requirements I can imagine would be covered by this and the cheapy type blaster from what I can see. Cleaning off some rust or paint sounds about the limit for me anyway - and the jump up to more industrial would be significant. Still I think some kind of home made cabinet would be in order.
I take it that the connectors are reasonably standard so if I buy this compressor and then some tools from Aldi or Lidl, they will 'just work'. I know it sounds unlikely, but one can hope!
Oddly. Now I've found them...
I can find ManoMano which looks like a good site and I can find a KIEI compressor on eBay (though the one I've found doesn't look that great), but I can't find a KIEI on ManoMano.
Actually, I don't want a specific recommendation (though I would be glad of some), but I wanted to check out what I might need.
My main confusion is CFM. Despite having read various posts and watch some You Tube videos, I am still not entirely clear if CFM is the cubic feet that go INTO the compressor (at one bar) or the cubic feet that go out of the compressor at (say) 10 bar. I am imagining that one is of the order of 10 times more than the other (9cfm out at 10 bar presumably means 90 in).
You will ask what I want it for? Well, apart from rounding of my collection of tools with which I lack any obvious skill, I have a number of ideas.
Most immediately I want to be able to see if my steam engine (2 x 2.5 inch cylinder) will run. I don't desire to run it at full pelt for half an hour, but it would be nice to know if it could turn over.
I'm also interested in small scale sandblasting at some point, a little bit of air for cleaning out holes and swarf in hard to get to places (suitable PPE will be employed) , perhaps some painting at some point in the future.
But as much as anything it's to provide a generally useful facility for the things I don't know what I want to do yet.
It MUST be quiet (ish) 60 - 70db seems a reasonable sweet spot. I'm thinking of something around 9 - 12 cfm, 24 or 50 litre tank and 9 / 10 bar. Of which there seems to be a wide range.
I did note the video which Jason posted recently, but was unable to read the brand on it. it sounded good (which is to say fairly quiet).
As usual and comments will be appreciated
|Thread: What Did You Do Today 2020|
I've been a bit quiet the least few weeks as a bathroom refurbishment interrupted play. AS usual with these things, you peel a layer back and find more problems and so it goes.
However, in the background I've been making a saddle clamp for my mini lathe. This, in some ways was an act of desperation. Desperation for parting off (a common whine!).
Some considerable time back, I got a decent QCTP from Arc and the first few partings off of steel went really well (by my standards). Not much digging in, swarf not dust coming off and I was delighted.
However, either over time or at some point, this all seemed to stop working. parting off, grooving, treppaning could only be done with the utmost delicacy or very nasty things happened.
One of the you tubes I watched recently talked about saddle clamps, so I thought I'd have a go. I'd already made a topslide clamp which had no effect on the parting off at all.
As part of the process, I had a look at the saddle and put an indicator on it there was well over a thou of movement up and down, which I thought was a bit much. I then nipped up the nuts which grip the saddle to the underside of the bed and got to the point where the movement was something like 8 microns. I had to stop that that point (as if I could do better) as, although the movement was smooth towards the chuck, in the last part towards the tailstock it was very stiff. I'm assuming that there is just a bit of wear in the area where I've been cutting.
Anyway I found that interesting.
Here's a drawing of the clamp.
The hinge is bolted under the front of the saddle and a 6mm pin (not shown) hinges the Clamp rocker. Half way along a half round bar sticks through and when the screw at the back of the saddle is tightened it brings it up to clamp under the ways. The idea is to ensure the clamping force is central rather than at the rear end only which I've seen on some designs.
I actually only trimmed the ends of the Clamp Bar, which gave a better bearing for the bar and also prevented the bar from wandering out of the Clamp Rocker.
Here's the part
And here it is on the saddle with the clamp off
and less than a quarter turn later, no.
The socket head bolts at the front and back are counterbored to keep out of the way of the saddle mechanism (in the above image specifically the jib screws).
I did some sums and thought that I only needed a few thou to accommodate the forward and back movement of the clamp rocker as it raised and lowered. However, between possibly bad maths and imprecise location, I ended up with this end overbored (6.5 rather than 6 and 11.5 rather than 10.5 for the counterbore) to accommodate some movement.
I've not yet tried it out. I wanted to quite whilst I was ahead tonight. Also I will never know if the improvement was due to tightening the saddle or the clamp - though I suppose I could try without it first..
|Thread: Digital readings|
I'm mixed like others. Small measurements are millimeters, medium sized ones are imperial and very large ones are metric. the medium sized ones (yards, miles, kilometers, meters) get blurry and a bit confusing.
For engineering, I've chosen to be entirely metric which can be a drawback when sourcing designs.
What I hate about metric though is that there is no 'thou'. My level of precision is roughly around a thou. Actually, with my big mill it's roughly around 0.01mm (on a good day and with a following wind). But I find it easy to say, 'parallel within about 2 thou', but saying 'parallel within about 0.05mm' sounds uncomfortable.
Accordingly, I often post both in threads and might say something like, 'I faced the piece to 10mm and was within about 1 thou'. Which is silly really.
Could we not have a term for 0.01mm? A Cent? than I can say that 'I faced the piece to 10mm and was within about 3 cents' which doesn't mix scales...
(Steve - sorry if I've just booby trapped your thread, but it's sort of relevant).
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.