Member postings for Simon Williams 3

Thanks John. I look forward to trying it out.

As a non sequitur (apologies moderators) the Jacobs spindle nose chuck you let me have works a treat. I cheated and bought a D1-3 back plate blank, rather than making one from scratch, but the chuck is in good use and I've got a repeatable run out of about 1 to 1.5 thou swapping collets and work in any combination.. I can do better than that with a bit of judicious bumping, but the chuck is several times better than anything else I've got and I'm very grateful to you for letting me have it.

All the best

Simon

I've got half a tooth in my upper right mandible....

Seriously, if anyone is hankering to follow the details of the label in my Mk1 gear box as above, I can't make the arithmetic work out. Interestingly the kit of bits on ebay just now (John's link as above) doesn't contain a 52T gear, nor yet a 44, and neither refers to a 63.

Ho hum

Thanks John for the messages.

Rgds Simon

Ah-Hah!

Thank you John, I think you've just explained the missing link.

So for my elderly S7 with the half speed gearbox drive, I need a 17T gear to bring pitches of 1.0, 2.0, 3.0 and 4.0 mm within the setting range of the gearbox. EG for 1.0 mm pitch I put gear T as 17T, then set the gearbox in the 36 TPI slot.

For 1.5 mm pitch I put gear T as 34T, but now the gearbox output to the lead screw is running at twice the expected speed, so I set the gear selector to twice the TPI in the table above (= half the rpm) to bring the travel speed of the lead screw back to where it should be. So I set the gear ratio for 48 TPI not 24 TPI, so the lead screw runs at half speed.

In my 1.00 mm pitch example, I can't use the 34T on the tumbler, as this would mean I needed to set the gear box for 72 TPI and it doesn't go that high (slow). I can do 2 mm pitch with either a 17 T gear (and set 18 TPI) or use the 34T gear, but then I set the gear box for 36TPI.

And so on. What larks eh? I'm off to make a 17 t gear.

All this started from wanting to cut a nut to "fit" a 2 mm pitch screw - the buttress thread on the tail of my U2 collets for the Deckel grinder. I was curious to see if I could get any nearer than cutting 13 TPI, which, crude though it is, actually worked quite well.

Thanks all as always

Simon

The mystery deepens! - or at least my confusion is ripening.

The input gear train of my QC g/box looks like this:

xxxxx

Looking down to see the hidden gear looks like this:

xxxx

So a 12T gear drives an idler (57T), which drives a 19T/57T combination. The 57T drives the wide 72T of the g/box i/p shaft. Hence the gearbox runs at HALF the speed of the lathe spindle. OK so far.

Inside the cover of the gears is a label:

xxx

BUT (if I've got my sums right) the centre distances of the fixed studs of the banjo don't correspond to those of the proposed gears on the label.

Measuring the lathe banjo, the centre distance between the two fixed studs is 1.900 ins, which works OK for two gears as fitted of 57 and 19 teeth. The centre distance of the second pair - the second fixed stud and the g/box I/p shaft is 3.225 ins, matching the tooth count of 57 and 72 teeth.

The label shows to substitute a 60 and a 44 tooth gear pair on the first two studs, so the centre distance will be 104/2/20 = 2.6 ins, not 1.9 ins as on the banjo.

The second pair, on the second stud and the g/box shaft are 52 and a 60, so 112T total, so centre distance 112/2/20 = 2.8 ins. The banjo centre distance is 3.225 ins.

Have I misunderstood something?

Thanks as ever, Simon

Brian -

Have sent you a PM as suggested, and look forward to hearing further. Thx Simon

There's always something to trip you up...

I've spent a while over the last few days making a 33 and a 34 T gear, also a 24 and a 26. Gone to play with cutting metric threads with then this morning, and fallen foul of the fact that the gear A on my S7 is a 30/12 couple. Uh?

Of course the answer in in the archive. I quote (from a thread dated 27.2.2012 called "Myford Quick Change Gearbox":-

Mike,

You are not getting the full story. So before you get in too deep......
In no particular order:
1. The last gearbox of the type you have was Serial No. QC (for Quick Change) 2500. QC2501 was the first "modern" one.
2. It is thought that many early gearboxes were retrofitted in the factory with hardened cogs, but no records were kept. Also quite possibly from some point before QC1950, hardened cogs were fitted as standard.
3. The leadscrew on your none-gearboxed machine has quite probably got a different plain diameter at the headstock end, as in smaller than what you require.
It must fit the hole in the gearbox casting closely for obvious reasons.
4. It is somewhat trickier to align the gearbox with the leadscrew, but it must be done and done carefully or the hole in the casting for the leadscrew becomes worn. The "modern" box is almost self aligning as it goes right through, but it still needs doing.
5. To align the gearbox properly, you need a spacer strip between the gearbox and the top two fixing screws along the bed shear. It is just a flat strip with two holes in, but I have no idea what the thickness is. That is a left over from the earlier ML7 fitting.
6. Your gearbox runs at half the speed of the "modern box" to cut the same thread. That is to say, your output gearing at the right hand end is 1:1, whereas the modern box is 2:1 at the left hand end. There is no chance of you altering the principle to be the same as a modern one as you won't make it fit!
7. A consequence of this that you also need a 12/30T FINE FEED TUMBLER GEAR A1974A/1 as it is termed on the Myford/RDG website to drive the standard fixed quadrant geartrain. The modern box uses 24T/30T and hence does not have to be a combo cog.
8. Do not try and use the Myford modern screw cutting details as in a later manual as you will end up with a times 2 factor as above, but you can do far better none imperial threads than the earlier Myford tables.

9. The guts of the boxes are identical and interchangeable apart from the shaft differences of course

Think that's it.

You have some way to go to get going.

Dennis

And I do indeed have the older gearbox on a S7 of the same vintage.

So, I have discovered that the banjo won't drop far enough to allow me to fit my new 33 and 34 gears, I'll have to modify the banjo slot to do so. Is this opening another can of worms?

Having got the gears to mesh, I can in principle adjust the top lever and side lever selections to choose half the TPI the table above indicates, as my gearbox will be running at twice speed. I've yet to think this through, but I doubt I'm the first - does this work?

Rgds as ever to all, and thanks for the help.

Simon

edited to remove a yellow winky face I didn't ask for....

Edited By Simon Williams 3 on 18/03/2017 13:08:11

Good evening all,

Just to clear up a piece of misinformation on my part, the driven bevel gear has a threaded nut above it which opposes the lift force otherwise separating the two bevel gears. There is a tangential screw through the side of said nut to lock it in position on its threaded portion of the vertical spindle, and to set the engagement of the two bevel gears.

I didn't discover this until I started taking the spindle apart, as the adjusting nut is out of sight until the top bearing adjusters are removed (and the grease of ages dug out of the way.)

Rgds to all, thanks NDIY for your help, though I haven't found drawings of the internals of the milling heads yet, only the main machine construction.

Simon

Good evening all!

Magpie that I am, I was unable to leave this on the shelf of a junk shop some while ago, and it's sat on a shelf in my (junk) shop ever since, gathering dust as you can see. I've never used it, but only because I've got nothing with a corresponding socket, and can't quite bring myself to modify it.

The threaded portion is M16 x 2.0, and the register just to its left is 17.94 dia. The minor dia of the taper is 19.24 and the major dia is 25.58 (all in mm). The length of the taper along the centre axis is approx. 24.8 mm as near as I can measure it.

What does it fit into?

Thanks, as ever, for assistance!

Best rgds Simon

It's possible (though perhaps unlikely) to connect the three coils of a three phase motor so that one is in opposition to the other two. If so, the two correctly connected coils will establish a rotating field, which the rotor will follow, but the reversed third coil hinders not helps, taking more current in the process.

If I've understood correctly you have connected the motor in delta to run from 220 volts. Did your test house do the same, or did they run it in star on their 400 volts supply? Can you post a diagram of how the motor terminal box is wired?

I would suggest that the reversing switch is an unnecessary complication at least until you can get the motor running comfortably. It's just adding to the confusion at the moment.

If it is the motor heating up and the machine stays cold its unlikely to be the mechnicals downstream, the problem is in the motor or the drive settings. Ive also heard tell of problems with some motors on chopped up supplies generating. internal circulating currennts but I'm pretty sure if that was your problem you would get the same heating effect on a vfd.

Rgds Simon

Why did he never find time for a.haircut?

Hi John, my TS light vertical mill table is 6.309 wide by 28-1/4 long. Has three slots 0.5 wide, and then the two centre lands are 1.500 wide each. The outer lands at the edge of the table are 0.905 wide. If you add up the lands and slots you don't quite get the total of 6.309, maybe my digital un-verniers need calibrating!

HTH Simon

Could you post a picture of the left hand of the headstock - end on so we can see the gear train please. You've took the cover off, and there is a picture of some of the gears but the rest are lost in the shadows.

Thx Simon

Thank you MichaelG. There's a bit of a polish needed, to be sure, but it'll clean up. That base could be a bit of flat steel? But I'm minded to ask "how did it get broken" - was it dropped? I can't see evidence of it falling over, no bent handles etc, so I still think you're on a winner.

Good luck, keep us posted, do!

Rgds Simon

Yes.

Couldn't find the photo's, but a Centec is worth good money, whichever version it is. Read up the details on **LINK**

Be interested to see which model it is.

Rgds Simon

John I sent you a PM.

HTH Simon

I'm in West Gloucestershire, nearly S Wales, but my brother lives in Great Hucklow, we were visiting for Christmas. Shame the shop's closed, but the cutlery we bought is in good service everyday. So is the grinder!

Rgds Simon

Posted by John Stevenson on 02/02/2017 23:12:21:General enquiry.

What lathe can handle a 17" faceplate on a D1-3 fitting? Big plate for a small fitting and must have to be a gap bed.

Are Harrison M250's or 300's on D1-3 ? Asking because found one of those as well.??

My Mk 2 Bantam will swing 18" in the gap, but whether it's prudent to do so on those three little studs of a D13 camlock I'm not so sure. If the Bantam will then I'd expect the Harrison to do the same.

There are two 18" faceplates on d13 camlock been for sale for ever on ebay, I've been eying them up but don't have a use for one, And in any case, having one will only lead to the experiment "is it safe to do this"!

Simon

Hope you're not using it as a bearing puller....

And my thanks to Mark Smith for setting my history right.

Best rgds to all. Simon

Ive been musing on the strange looking alternative work holder. The screw driver blade right of picture looks like a detent blade, and the air fitting might be to intrpduce air ito the bore of the fixture, perhaps to make ot easier to turn? Not able to see what's up the centre, but could this be a fixture to present a slitting saw or a side and face cutter to the grinding wheel.