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Member postings for Mick B1

Here is a list of all the postings Mick B1 has made in our forums. Click on a thread name to jump to the thread.

Thread: English dialect
25/09/2017 13:15:45
Posted by Gordon W on 25/09/2017 09:58:54:

...She s till can't understand " couple", as in " I'm just going for a couple of pints ".

She ought to. It's literally the same, and colloquially used with the same imprecision, as the German "ein Paar".

Thread: A bit of humour
25/09/2017 12:11:04

frog.jpg

Thread: Chuck a mile out
24/09/2017 14:51:46
Posted by Martin Connelly on 24/09/2017 13:44:48:

If you want accuracy then don't use a self centering chuck....

Depends how accurate you need it to be. It's quite reasonable to expect a new 3-jaw to be concentric to a thou or two and some - even budget ones - can be better than that. Plus there's always the option to machine a set of soft jaws to achieve the same or better.

I think the OP's quite right to think something's more than usually out of line when a chuck that appears to be correctly fitted shows 10 thou eccentricity.

Thread: A bit of humour
24/09/2017 13:20:30

Geoff Perkins' Dilbert cartoon reminded me of this one I saved from somewhere:-

Dilbert's Theorem

Dilbert's "Salary Theorem" states that "Engineers and scientists can never earn as much as business executives and sales people."

This theorem can now be supported by mathematical proof based on the following two postulates:

Postulate 1: Knowledge is Power.

Postulate 2: Time is Money.

As every scientist knows: Power = Work / Time.

Since Knowledge = Power, then Knowledge = Work / Time.

Since Time = Money, then Knowledge = Work / Money.

Solving for Money, we get Money = Work / Knowledge.

Thus, as Knowledge approaches zero, Money approaches infinity, regardless of the amount of work done.

Conclusion: The less you know, the more you make.

QED!

Thread: Chuck a mile out
24/09/2017 11:08:53

When you take out the chuck jaws to check the sequencing, look at the scroll and the jaw scroll segments to check there ain't a piece of swarf wedged in there.

Look at the front face of the chuck whilst running and see if there's any wobble.

Edited By Mick B1 on 24/09/2017 11:10:16

Thread: moving house & workshop
23/09/2017 09:38:25

Dunno how big your workshop is - mine fits in a single garage, largest machine a Warco WM250V lathe, plus workbench, bench drill, big vice and lots of materials and sundries - and I used the local firm Hunts when we moved from Redditch to near Leek a bit over a year ago.

They did a decent job, quickly and without fuss.

Thread: WM250 thread cutting
21/09/2017 16:08:38

Looking at the screwcutting chart for my WM250V, the 20 TPI config is:-

H 30

.....|     (had to put dots in to get the connector in the right place )

75 80

|

60 H

...with feed setting A.

I've found the charts to be correct for screwcutting on those that I've done.

Is the WM250 without the 'V' a different animal?

Edited By Mick B1 on 21/09/2017 16:10:15

Thread: Carbide Tips from Hong Kong
21/09/2017 12:45:05

Which is which? The LH one (looks to be TiN coated) has an apparently smoother finish, but the RH one looks sharper - and you mention 1 thou cuts.

I can't actually recall *ever* using any tips that made a particularly clean job of 1 thou cuts on stuff like silver steel, and that's one reason I've preferred HSS for most jobs for most of the 40-odd years I've been machining.

In the light of what you and Ketan have said, I'll try some 'definite' branded tips and see.

Thread: Drill flute orientation
21/09/2017 09:12:07
 

Pun didn't work - deleted.

Edited By Mick B1 on 21/09/2017 09:16:26

20/09/2017 20:51:26
Posted by Robin on 20/09/2017 20:35:46:

If you put the cutting edges horizontal you can apply a rigid sideways displacement to a wandering drill tip by running the cross slide up against it. This cuts a perfectly centred conical dent which guides the bit back on course as you release the pressure.

Yeah, yeah, but haven't you now actually got a truncated conical dent, with a flat at the bottom that's wider than the effective width of the chisel point of the drill, so losing any guidance to continue cutting on centre?

Apart from internal elasticity, that is. That's why I think it pays to pause and let it cut on springback to centre. Or maybe that's just another variant of what you're suggesting.

Maybe it's easier just to leave some mysteries alone... smiley

Thread: Parting Off With an Interrupted Cut - Is it a daft idea?
20/09/2017 14:32:26
Posted by Muzzer on 20/09/2017 12:39:47:

I'd part it off so the tool straddles both sections, round and lumpy, only just shaving the lumpy bit.

If you do that, there'll be side loading on the tool from the chuck side, and by the time you hit the lumpy bit, the blade will already be deflected rightwards. I've always thought you need to equalise the load both sides of the parting tool to get a straight plunge - and if you don't get one o' them, there are several undesirable possibilities, depending on exact circumstances...

20/09/2017 08:53:10

While yer've bin gassin', yer could've sawed it off wi' an 'acksaw an' faced it in a 4-jaw or milled it flat in vice wi' a flycutter or owt... :D

Edited By Mick B1 on 20/09/2017 09:12:12

Thread: Drill flute orientation
19/09/2017 13:07:01

I also tend to mount drills vertically - when it occurs to me to think about it - because I think the chips can clear a little more easily and evenly that way. But of course that only applies in the first diameter or so of depth, and may be spurious anyway.

It seems to me it's more important to give plenty of time to cut until the full diameter of the drill is engaged - so that if the drill is deflected by uneven lips, even by an invisible amount, you give it time for the elasticity of the drill body to spring it back nearly to truth, and so the full diameter enters a hole as near size-and-centre as makes no difference.

Thread: Drilling Tapping and cutter sharpening etc
17/09/2017 12:48:37

Pretty comprehensive piece of work. Thank you.

Edited By Mick B1 on 17/09/2017 12:48:54

Thread: Further question re large drills
17/09/2017 06:38:17
Posted by peak4 on 17/09/2017 00:08:03:

Assuming the centre hole in the tang is still retrievable, sharpen the drill first, so the pointed end is actually in the middle, and drill a small bevelled hole into a spare blank arbour to fit your headstock.

Use this to locate the sharp pointy end and turn between centres.

Bill

...Or bore a hole about half a diameter deep and a light drive fit on the drill's circular land in a bit of scrap material in whatever chuck you happen to have in place. Use the tailstock centre in the drill's tang hole to push the point into your bored driving plug, and you should then run very concentric, for a series of light cuts down to a diameter suitable for a drill chuck.

Thread: Primitive gear cutting method
15/09/2017 19:22:50

I'm guessing that you'd need a spiral-flute tap if you were trying to hob thin gear-wheels by this method, so that you'd always have a tap thread point in at least one of the toothspaces to give drive? IIRC purpose-built hobbing machines drive the blank spindle in a set ratio from the hob spindle, and you don't have that here.

Perhaps even the spiral-flute tap might not work if the flutes were wide enough to miss all the teeth currently being cut.

Edited By Mick B1 on 15/09/2017 19:24:22

Thread: Carbide Tips from Hong Kong
15/09/2017 17:29:54

I've just received 10-off small carbide tips: DCMT070204 US735 DCMT51.51

...for which I paid £4.69 including carriage. Supplier is in Hong Kong, and actual lead time was 12 days.

After a couple of moderately aggresive cuts on silver steel, they seem good. This price is of the order of a tenth what they'd cost from a UK supplier.

Is this part of a dastardly plot to defeat our own tooling distributors by undercutting them with loss leaders?

Have our own suppliers been ripping us blind?

Or, as I suspect, is it a bit of both?

Anyone else have any experience to share about cheap tips from abroad?

Thread: Primitive gear cutting method
15/09/2017 17:14:31

What if the pitch of the tap doesn't divide exactly into the circumference of the blank at the bottom of the cut?

Thread: How can I keep a deeply drilled hole straight?
15/09/2017 05:39:40

It hadn't occurred to me to suggest these before, but having thunk the thought...

https://en.wikipedia.org/wiki/Gun_drill

...of course, you need to consider how expensive a solution is actually justified by the requirement surprise.

14/09/2017 17:58:49
Posted by KWIL on 14/09/2017 16:53:48:

When Jason says evenly ground, that means both lips the same length and angle.

That's right. And it's important not just to withdraw often to clear chips, but also feed gently to allow both lips to cut. Forcing the drill through hard will accentuate any effect from uneven length lips, and it's pretty hard in 6mm. to get both identical to very close tolerances.

For the hole to wander, the drill body has to flex, so the start hole from Jason's short, stiff stub drill - if you've got one - will also help a lot by giving straight support to some of the full-length drill when it's going on into the deeper reaches of the 'ole.

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