Member postings for Andyf

If you have one of those Weller pistol-type soldering irons, that will demagnetise items which fit through the hairpin-shaped bit. Pass them through, but don't release the trigger until they are a foot or so away.

Might not work too well for digital calipers, though. The plastic parts wouldn't take kindly to contact with the hot soldering iron.

Andy

I'd be interested in details of those, Derek.

Like your Monodex, mine has splayed out at the front, and no longer responds to being squeezed together in the vice, because the edges have got pretty battered over the years and don't cut cleanly any more.

Andy

I think Mason ws thinking of a lathe mounted on a Singer sewing machine stand, Ady, sans cast iron drip tray and legs. I offer no opinion as to whether such a stand would bear the lathe!

Don't be too pessimistic about floor loadings, though; I wouldn't be too worried if three 20 stone (= 1/3 ton) rugby players stood shoulder to shoulder on my bedroom floor. Actually, that would be a rather worrying prospect, for reasons other than weight.

But as you say, Unimat or similar sized lathe would be ideal as a starter lathe for Andrew. For 20-odd years my only lathe was this £25 secondhand Perris, which can be lifted with one hand, motor and all, from a cupboard and used on the kitchen table. It would easily fit in a suitcase and has an induction motor which (as others have said) is very quiet.; in use, it's a lot less noisy than a food blender.

Other, more modern, miniature lathes which spring to mind are the Peatol and the Sherline. Or the fabulously expensive Cowells, into which my Perris has now evolved,

Andy

Though I've never used a treadle lathe, L C Mason asserts in his book "Using the Small Lathe" that it is quite practicable for a small machine, and gives instructions (mainly concerned with adding weight to the flywheel) for converting a treadle sewing machine stand to the purpose. I think he regarded a "small" lathe as being one of up to Drummond or Myford size.

If there is a significant other in your life, maybe you could convert an exercise bike and persuade them to keep fit whenever you fancy a bit of machining!

Andy

Hi Joe,

As they say in the car manuals, re-assembly is the reverse of disassembly .

I don't know your lathe at all, but on mine the procedure is to put things back together and then move the leadscrew up, down or sideways until the half nuts will close easily on it at the headstock and tailstock ends.

Up and down is dealt with by loosening the leadscrew bearing block fixing bolts at one end, clamping the half nuts up at that end, then tightening the bolts up. If the leadscrew doesn't rotate freely, the holes in the bearing blocks may need enlarging to allow a bit of wriggle room. Then repeat at the other end of the leadscrew.

Sideways adjustment can be accomplished, if there is sufficient wriggle room on the bolts which hold the apron to the saddle, by loosening them, closing the half nuts, and then tightening the bolts up again. If that doesn't work, shims behind the bearing blocks, or skimming a bit off their backs, may be necessary.

You can often diagnose what treatment is needed by closing the half nuts half way along the leadscrew, while observing closely to see if it flexes at all. If so, the leadscrew will be put under severe strain when the carriage gets near one or other (or both) of the bearing blocks.

Andy

Apologies for the typos in my last post. Kipper the cat was tramping on the keyboard and obscuring the screen.

...held out far enough that it doesn't bump...

...so the motor doesn't hit their knobs...

...allow access to the T-slot... (that can't be blamed on the cat)

Andy

Nothing wrong with the drill/driver idea, Robin; I've seen recipes for power feeds on the net which use 'em. They have torque clutches, too, but those are often such an integral part of the housing that you can't really use them. The speed might be too fast, though, in the sense that on minimum speed there could be insufficient torque, so a bit of gearing down may be needed.

Thought needs to be given to clearance around the power feed. Assuming you put a motor behind the feedscrew bracket, it must be held out far enough that is doesn't bump into the X-axis base, about an inch of which is exposed when the table is as far to the left as it will go. Similarly, the "tightened up" position of the column clamp levers may need adjusting with different sized washers, to the motor doesn't hit their knobs. At the other end of the table, where my control box will be, 2" of the X-axis base is exposed when the table is fully to the right, so anything bolted direct to the end of the table will need to be pretty shallow, and allow axis to the T-slot at that end.

Andy

Hi Robin,

My motor is similar to that, but bought on Ebay, direct from China.It's a bit like this one , though with a much longer motor. The specs at Technobots are hard to find, but it may be that the one you refer to is 25mm diameter (27mm across the plastic shroud which covers the gears) and with a 4mm output shaft. Mine is 35 mm and 37mm with a 6mm shaft, and (like the one I linked to), the shroud is metal held on with screws, rather than a push-on plastic thing, and has six M3 holes on the end of my shroud, so the motor can be fixed end-on to a metal plate, whereas the MFAcomo ones come with a useless thin, bendy 1mm thick bracket (I know, because I bought one from Maplin). Being able to fix to the shroud means the motor is restrained by being attached at its torquey end.

I can't comment on torque, but Mike finds his to be perfectly adequate. Something like crashing the spindle into a badly positioned clamp would probably make the motor tear itself apart. If there was room for one, a breakaway clutch wouldn't be a bad idea. A wooden key fixing the 60T gear to the handwheel might be easier to implement.

For speed control, I will be using a Velleman PWM kit, built some time ago. Mike used a Maplin ready-built one. The Technobots one has an on-board reverse, but that would be pointless in the circuit shown on Mike's page. There, SW1 sets the cut direction, either to the left or to the right.. SW2 (which is centre-off) sets the cut in motion, with the motor's speed regulated by the controller. When the table opens the limit switch at the end of the cut, the motor stops (very quickly, because its terminals are shorted by the relay). With the limit switch open, the motor cannot restart in the cut direction; it will only start in the return direction, when SW2 is switched over. When that is done, the motor runs at max speed under full 12V power, taking the table back until it opens the other limit switch, stopping it ready for the next cut. Again, it won't restart until SW2 is flicked over for the next cut. To stop the table part-way, either switch can be flicked to its midway centre-off position.

Once the speed for the cut has been set, the speed control knob can be left alone throughout. I reckon that my feedscrew will do about 60rpm on the return, so the table will go about 1" in ten seconds. That's only half as fast winding quickly by hand, but boredom shouldn't set in except on very long cuts.

Hope this explanation helps a bit. Sorry it's so complicated, but you can imagine the headscratching which went into designing the basics of the circuit in the first place.

Andy

One way would be to put it on a longish and hopefully straight bar between bearings of some sort, then rev it up slowly (perhaps using an electric drill). If it's out of balance, the bar will flex towards the heavy side, and a felt-tipped pen mounted close to the wheel when static will mark it to show where weight should be removed. This would need a number of iterations at gradually increasing speeds, and a supply of different coloured felt tips so you can tell new marks from old.

Andy

Robin,

The reference to a double worm reduction drive probably stems from the articles in MEW issues 14, 15 and 16. Those dealt with a power feed for the Westbury miller, which was redesigned and improved into the DW Mk 1, but having read the articles in the digital archive a week ago, I think the design would go on a DW with only minor modifications.

I too have a Mk 1, but that design looked a bit complicated, with its two worms, universal joints and telescoping drive shaft. I'm very slowly concocting a power feed on somewhat simpler lines. The basic idea is to put a cheap £9 Chinese 12V gearmotor (looks very like those supplied in the UK by MFAComo) with a 120 or 148:1 (I forget which) ratio in a housing of aluminum square tube. The tube will be attached to the rear sloping side of the tray-like feedscrew bracket using a good quality door hinge. A plate will be fixed to the front of the motor and tube, and will extend far enough to carry a stud with a Mod 1 32T idler gear, in permanent mesh with a 48T on the motor output shaft. I have trued up the 1" diameter boss on the handwheel, and bored out a 60T gear to fit on it. The general idea is that the whole motor/32T idler assembly can be swung on the hinge to bring the idler in and out of mesh with the gear on the handwheel as required for power or manual feed. The motor will be under PWM speed control, with an electro-mechanical control system, including autostops like Mike's shown here , which allows for slow travel in either direction for cutting and a quick traverse back at the flick of a switch, without altering the speed control. The control box will be attached to the LH end of the table; there isn't room for it at the handwheel end.

The gears came from Technobots, but have had to be reduced both in thickness and in length of boss to get things to fit between the dial and the handwheel. Indeed, the idler has no boss at all.

Andy Franks

Felt a bit disappoined by last night's Newcomen Beam Engine episode. If viewers missed a very fleeting remark during the first few minutes, they may have thought they were watching the restoration of a 250 year old engine, rather than of a 1986 reproduction. And, though handmade bricks and hand-hewed coal are also part of our industrial heritage, there was too much of our hero in the brickworks and down the mine at the expense of the engine itself.

Andy (rapidly turning into a grumpy old man)

You're the one on the left? I hadn't realised that ,

I'm asking this in ignorance, and not trying to be argumentative. Does the TiN coating not wear off cutting edges fairly quickly? And, on the same theme, is it used more on "throwaway" tools, rather than those which are likely to be resharpened?

Andy

David, I use XP and IE. Though hitting the compatibility button usually sorts things out, it didn't here. I think it may be because the two pics in Gray's post are side by side, rather than one above the other. I had to highlight the text in Andrew and Gray's messages, copy it and paste it into the reply box. Happily, I remembered to delete it before making my submission.

I entirely agree that knurling is not a gentle process, as it involves both cutting and displacing metal across the width of each of the wheels.

Andy

For what it's worth, I clamp about half the width of the knurls on the end of the stock, hard enough to make some impression, then start the lathe running and traverse the knurls along and back using the leadscrew handwheel, clamping up a bit more each time I get back to the half-engaged start point. After the first pass, I stop the lathe to see if the pattern looks right. As Gray says, sometimes the diameter of the stock is such that the knurls "double", producing a pattern twice as fine as I want. The only remedy for that seems to be to turm a few thou off the stock and try again.

If the first pass looks OK, I continue to and fro, clamping the knurls a bit deeper each time until the depth looks right. It's as well not to go too deep; this can result in sharp points on the pattern, making the finished job uncomfortable to grip.

Use plenty of lubrication. It does no harm to stop part-way though and brush off some of the debris. On my lathe at least, it seems best to angle the shank of the knurling tool 4 or 5 degrees towards the headstock, rather than having it exactly perpendicular to the work.

Andy

There I was, thinking you had found a neat way of using mellow yellow to show yourself as the originator of the thread. Now it turns out that you've got jaundice. Your message of 16:20 is part yellow, part normal grey.

The lost first sentence seems odd. Until someone comes up with a better idea, use a dummy sentence like "The quick brown fox jumped over the lazy dog", and paste it in a few times so they are deleted one by one as you amend your post. Then click into the body of the post a few times to get rid of any remaining quick brown foxes.

Andy

I got some for a job two or three years back, and the remainder is still perfectly OK. It's kept in the house, though, so has never been subject to extermes of temperature either way.

Andy

If it's meant for 230v operation, it'll draw around 13A and be a bit on the limit for a domestic plug and socket.

At 1200 deg. C , it should be good for brass and bronze as well as aluminium.

Andy

Joe, it's just something I've seen on the Internet but never tried myself, so I can't really offer any advice. The only half nut I've ever made was in brass to fit a baby lathe which had a solid nut before, making the saddle a pain to wind along the bed.

That said, I doubt if making the thread will be the hardest bit. Each of your half nuts will have dovetails or something so they can slide in and out of engagement, and some sort of slots or pins to link up with the cam action lever which operates them. A milling machine may be needed to create the dovetails (or whatever).

Andy

Delrin is a trade name for one type of acetal plastic, Joe. Acetal is engineering plastic, used (for example) to make the change wheels for small Chinese lathes. It can be had from many of the places which sell metal to the hobby, and can be found on Ebay, too.

Here's a thread on making a nut from it "the easy way" link .

Andy

If no-one on this site has a similar lathe and can measure the pulley up for you, you might try a request for information on homeworkshop.org.uk.

Alternatively, if you know the motor rpm, you could try calculating the pulley sizes required to produce the spindle speeds of 125 to 2000 rpm quoted here.

Andy