Member postings for Simon Williams 3

+1 for stainless for me, but do make sure it's 303 grade which is nominally free machining, you'll likely get a much nicer thread. Lubricate the die well with something like Rocol RTD.

You can get free machining silver steel, but I've never worked with it. Ordinary silver steel would be a perfectly good material, though cutting threads in it is sometimes prone to tearing. But for making any thing scientific related go for stainless every time.

You could make a stronger job by drilling and tapping the end of your 6 mm rod with a M3 hole, then screwing in a long grubscrew such as a hex socket grubscrew (steel). These are made out of a very high strength material - or you could use an A4 stainless screw which is 316 grade by another name, so tough stuff but much the same strength as 303. A grubscrew in a tapped hole doesn't give the same concentrated stress raiser at the transition of diameters as making a male thread so it will probably be stronger. But be careful that the bit into which this screws isn't prone to damage - sometimes you end up moving the problem around!

HTH, can we have a picture of the finished repair?

Simon

Edited to correct my error over grades of stainless - 316 = approx. A4 grade, 304 = approx. A2 

Edited By Simon Williams 3 on 24/01/2019 13:34:27

Hi David, good evening, I was wondering how you were getting on.

That seems like an excellent outcome, and many thanks for the update. It's good to know that the original question has been put to bed.

Best rgds Simon

I’m tackling titanium, it’s difficult I know,

I’ve never tried it out before, so I thought I’d have a go.

There’s a lump I’ve had for ages, I don’t know where it’s from,

So I’ve clamped it firmly in the chuck. What could possibly go wrong?

Don’t let the stuff work harden, if the tool rubs you’ll regret it

Keep the feed free cutting, if you stop you can forget it.

Be bloody bold and resolute, but calm and reasoned too,

But don’t be heavy handed, a dig-in’s not good news.

Let the machine do all the work, the feed in automatic,

The heat it seems to generate is really quite dramatic.

But the swarf is long and stringy, razors in a caddle

It’s just as well the handwheel is the right side of the saddle.

According to the internet it might just set on fire.

Jeopardy’s exciting, the risks could not be higher

If I burn down our conservatory I’ll get absolutely slaughtered

And my wife’s long lost relations will all revel in my torture.

All is going swimmingly, my workpiece size is thinning,

The finish something excellent, for a short time I was winning.

But suddenly a horrid noise, a nasty clonky clunk.

Oh damn! My brand new lathe tool is missing a great chunk.

So I’ve had to change the carbide, and set it back in motion,

Approach once more with confidence, forgo my normal caution.

It’s nearly down to size by now, if I tweak the cross slide higher,

I’m sure I’ll hit the tolerance, and satisfy my buyer.

This endeavour’s just a past-time, I’ll enjoy while I may

But I need to stretch the boundaries, keep the brain cells from decay.

The alternative’s too awful, Eastenders’ not for me.

Or lounging on the sofa with reality TV.

Edited By Simon Williams 3 on 15/01/2019 20:36:21

My digital caliper I bought from RS

Mitutoyo Digimatic, one of the best,

Is now but a spanner with a number ever changing

Which bears no relation to size or dimension.

I’ve changed out the battery, no difference I fear

The numbers keep rolling, too fast they appear.

If I press the OFF button, the display clears correctly,

But with “ON” reappears with more numbers directly.

So I took it bits, took the circuit board out,

And cleaned it with alcohol, got a lot of muck out.

Then reassembled, with a battery new,

The same indication, oh bother and blow!

So now I’m quite stumped, my caliper’s duff,

I’ve fiddled with the perishing thing quite enough.

If anyone wants a nice kit of bits

To make a vernier from it, just to see how it fits.

You’re welcome to have it, I’ll post it for free,

All you have to do is to PM message me.

With an address of a home for Mitutoyo retirement,

And I’ll nip down to Aldi and buy a replacement.

Edited By Simon Williams 3 on 13/01/2019 17:20:38

Looks like a good model of the Big Bang and the Spiral Universe.

HNY!

Jason - good morning,

My series 1 gearbox has got this label inside the gear cover.

To the best of my knowledge this simply uses the same banjo as the (later) metric adaptor kit, but alters the selection of change wheels. I worked it out once long ago, and came to the conclusion that the gears shown on this table gave metric pitches as shown, so they allow for the 2:1 factor. I think!

Brian will maybe correct me if I'm wrong.

Much of this is examined in the links above to earlier threads, with John S's input 'cause he knew the history of how this developed.

I'd be interested to know if it is this early label in the cover on David's g'box, and we haven't bottomed out the issue of the size of the spindle gear on an ML7 and whether it is 30T or possibly 25T. My picture of a home brew mandrel cluster gear (the bronze one) assumes that the spindle gear driving the tumbler gears is 30T. But David seems to have a handle on the answer to his original question, so all of this is a bit academic. It's just nice to have these things sorted out and recorded in the archives.

Best rgds Simon

Edited for minor typo which had a disproportionate affect on the logic!

Edited By Simon Williams 3 on 11/01/2019 09:30:15

Hi David, good evening and thank you for the warm feedback and news that we've been of help. It's always nice to close the circle.

While changing gears inside the gear train will give the 2:1 step down, it's not always straightforward to assemble something which will actually mesh correctly. Brian's last post alludes to this. I side-stepped this problem by making special gears for the input (mandrel) gear as below. The one shown is for use with the alternative method of achieving metric pitches - keeping the standard gear train of the QCGB and altering the input gear (mandrel gear) That's what the above correspondence threads to which I linked examine. I see no reason why you couldn't do a mix and match of both approaches, in which case the mandrel gear needs to be 15 tooth.

The gear cluster on the left is the standard Myford QCGB 30/12T mandrel gear which you will recognise, and the right hand one is an adaptation of the same idea with the same 30T one end and a 17T the other. So one with a 30T and 15T would look very similar.

To the best of my knowledge such a thing isn't commercially available. If you want to pursue the same idea send me a PM and we can discuss further.

Someone will point out - perfectly correctly (so it might as well be me) - that this is a complicated way of achieving a simple outcome, and it would be more straightforward to ditch the metric kit completely and go for the special input (mandrel) gear option, as per the threads above. If you had the later style gearbox that would be a no brainer, but with the older gearbox there are pro's and con's of both methods. If you want use your metric banjo as Mr Myford intended we can make this work by using a 30/15T cluster. Depends I guess how much resources you want to devote to being able to cut metric threads.

One thing further - Brian am I right in thinking the ML7 uses a different mandrel cluster from a S7? I've got an idea that the 30T gear is peculiar to the S7 but I might be imagining things. If so we just need to confirm from David that he is working on an S7.

Best rgds Simon

Thank you Brian, I don't disagree with you though I couldn't decide whether to expect twice or half the intended pitch on the basis of what we know so far. Hopefully it'll be one or the other, in which case we know why it's doing it and how to fix it.

David we also need to know what TPI setting the gearbox is set for as well as the gear train tooth counts and the pitch actually being cut on the workpiece.

Best rgds to all Simon

Here's another thread which contains some more direct comparison stuff :

**LINK**

This includes pictures of the label inside the gearbox cover which should (if the right cover is fitted!) explain the difference in set up.

HTH Simon

Later model QCG's have a 2:1 step down gear at the output. The earlier model doesn't so the input gear train steps the speed down externally to the g'box. This means that the mandrel gear is halved.

The gear boxes are superficially the same, the difference is under a cover on the RHS of the gearbox. On the newer g'box there is a pair of gears which reduce the output by 2:1, on the older gearbox there is still a pair of gears at the output but they are 1:1.

In terms of pictures there is quite a bit of history buried in the forum of one against the other

Here's one such:

https://www.model-engineer.co.uk/forums/postings.asp?th=125630

And another:

**LINK**

I know there is a much older article on this which is quoted in one of the links above but I haven't found the url link yet.

If this is the explanation for the problems you have been seeing, then you are probably cutting half the pitch you meant to. Would you like to describe what input gears you have set up on the banjo and what pitch you have actually found. We can then determine if the explanation fits the evidence.

HTH Simon

Edited By Simon Williams 3 on 10/01/2019 09:04:37

Hello good evening

This return and carriage feed - or lack there of - is not peculiar to Apple, as my HP laptop running W10 suffers it. My desktop PC running W7 doesn't. I've given up.

So if I reach the end of a paragraph with my laptop, then press return. the cursor goes in front of the first character on the page. I then use the cursor down key to put the cursor after the carriage return and double line feed that have been added after my completed paragraph. I can also use the mouse and L click to move the cursor after the finished para'

I've taken to adding two line feeds and some buckshee characters when I want to add a photo. Then I position the cursor at the first line feed before pressing the camera icon to add a picture. This avoids the annoying placement of the first word of the new paragraph on the same line as the photo itself. The extraneous characters just act as a marker to start subsequent text.

Doesn't have to be a why. I just fixed a work round.

Rgds to all

Simon

Good afternoon all.

Spent my weekend worshipping the god of swarf, so here is the preparation for my repair to the broken leadscrew mounting casting:

And here it is assembled

xxx

And just to prove that it clears the channel in the bottom of the table casting (if only just):

The orientation of this photo is a bit odd, only so I could get the camera near enough. "Up" is about 10 o'clock.

So bung it all back together and it all fits and lines up and slides and wotnot. X travel now measures 18-3/16, which is a result I'm very pleased with.

Thank you gents for your help in determining that it needed surgery, hope your restoration s equally satisfactory.

Best rgds and a Happy New Year.

Simon

Ian -

Bush measures 1.243 OD (mostly) by 1.960 long overall. Material is visually bronze, not brass it's not yellow its pink. (phosphor bronze?)

I like the suggestion of having broken the casting by over-enthusiastic bush fitting, that's a simpler and more plausible suggestion than somehow it fell over leaving no other visible marks. The only thing is, that bush is a slack sloppy fit in the remnant of the proper location. The socket left is about 200 degrees of a circle so it's pretty easy to gauge the diameter, and although it's significantly scored it's pretty much round albeit oversize. I wonder if someone failed to realise there was a grubscrew locating the bush axially and radially, wound happily on some kind of extractor and only stopped when it was too late. Ping!

Best rgds Simon

Tonight's update:

Pulled the half nut out of the casting. It was a moderate press fit, came out with a bit of help from a piece of M12 studding. Could have used 1/2 whit, but it is a metric machine....

And here it is fitted in it's proper position.

There, that was an easy fix (if only).

Set up and machining tomorrow, after I've got the wood burner going well.

Rgds to all

One hell of a dig in to do that much damage! I know it's a light vertical, but I've had some serious work out of mine table travel notwithstanding. So I guess we'll never know.

So do please keep the updates a-coming, it's always interesting to see how other folks are getting on with machinery you recognise.

My best regards to you both

Simon

Hi Ian, yes I think your pictures just about seal the diagnosis. You're right though, I can't imagine how someone managed to do this much damage without wrecking at least something major, so I'm scratching my head a bit. I see no evidence of dings or bruises elsewhere, suppose I should be grateful it has survived this well.

I guess it doesn't matter too much, I've just got to get past that and find an honourable fix, even if I have to get someone locally to make the necessary mod's to this casting. I'll keep you posted.

And thanks to Miles for letting me hijack his thread.

Best rgds Simon

Well, nothing venture nothing gained, so I have stripped the table off the cross slide, and suddenly all becomes crystal clear.

Somebody had a major crash (tip over?) and broke the lead nut out of its casting. Somebody else devised a simple fix - put the lead nut in the other hole. What I have been seeing is the consequence of moving the lead nut 7 inches or so to the right.

Here's a closer view of the site of the break.

Which strikes me as relatively easily fixed, though I do need another milling machine to make a flat area each side of the original bore for the nut. I can then make a half clamp and clamp the half nut back where it belongs. I'm toying with whether I can do this with my horizontal mill, don't see why not with a bit of patience.

However the interesting part of the riddle remains, as I believe all the parts are original. There is a number 14 stamped on the main column above the s/no, and the same number is on all of the bits of the knee, including the table and the gib strip. So I'm lead to think that all the bits are there, but not necessarily in the right order.

Keep you posted!

Regards to all

Simon

Hi Miles, Ian

Thanks ever so much for your time and encouragement - Ian if you can easily take a photo or two that would be brilliant but please don't go to too much trouble as I think I can see what has happened (what has not happened) here. That second photo (Ian's post at 18:18) and Miles 9 inch measurement explain everything.

I'm out on the road tomorrow, but there's a sudden attack of enthusiasm on the horizon, as I think I see the answer to something which has been piquing my curiosity for years. It never made sense to me that nearly half the table was out of bounds, and now I think I understand why - and even better what to do about it,

I'll whip the table off tomorrow when I get back and see what it reveals. Keep you posted!

Best regards Simon

Hi again Miles, thanks for the additional info. My leadnut certainly looks like it belongs where it is! But there is certainly something odd going on here., and I'm starting to wonder if the thing to do is to remove the table and take a photo of the knee. I still think the basic problem is that the leadscrew should be threaded for its full length, which is where I started. and maybe that's something to do with fitting the long table on the original design of knee. With my knees (now there's another story) sorry knee the lead nut is inside the right hand side of the casting by 2-1/2 inches. I'm guessing that the knee for the longer table has the nut well to the left to give the extra travel and I'm beginning to see this as an easier mod' to do than making a complete new lead screw. I feel a project coming on.

If you do take yours off during the course of your refurb' please take a picture and maybe we can compare notes.

Best rgds and thanks again for your help.

Simon

Hello Miles, thanks for that. I've completely changed my theory that mine is a late model, as the serial number is V3485, which puts it off the scale into prehistory. I'd assumed given the 28 inch table that it was later rather than earlier, but who knows, maybe that isn't the original table!

The other revelation is that the table movement is 13 inches (12-7/8 actually) not 15, let alone any more. The stop going towards the right is the leadscrew tail bracket contacting the knee, the stop going left is the leadscrew running out of thread. Travel going right isn't the issue for me, the cutter is just about over the left end of the table by the time the movement stops anyway, but I don't understand why the right hand area of the table is out of limits, for the sake of cutting a thread the full length of the lead screw.. But your leadscrew appears to be the same so I'm assuming that's how Mr Senior meant it to be. Odd or what!

Oh, and I tried your trick with lifting the left hand supporting bracket, it's already high enough it isn't the problem as it passes the first recess anyway.

Best rgds Simon