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Member postings for Nigel B

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

Thread: Safety emergency stop switchs
19/01/2017 08:03:30

So I wired up one of these also from Toolstation in parallel with the stop switch...

Is this a typo ? Stop switches are usually "Normally closed" contacts & are wired in series.

Nigel B

(Just noticed that DJ beat me too it !)

Edited By Nigel B on 19/01/2017 08:04:11

Thread: TEC Strange wires
17/01/2017 21:22:56

Likely a thermistor connected to them and embedded in the windings?

Ditto, though it could be a thermal switch - have you tried measuring the resistance between the two wires ? Also, look inside the connecting box lid - frequently find a connecting diagram there.

If you are running the motor from an inverter, does it have a motor overheat input ? Some have a thermistor input - if yours turns out to be a thermistor, wire it to the drive as described in the drive manual so the drive can monitor the winding temperature.

Nigel B

Thread: Scraping class (again..) in Scandinavia..?
17/01/2017 20:03:39

We've really got to up our game on the engineering front in Britain, it's a wonder we still have any left.

You won't do that teaching scraping. Scraping on a day-to-day engineering basis has largely gone the way of planing & shaping - you won't find many courses teaching the use of those machines either. To move forward requires well educated school leavers choosing a vocational path to learn 3D CAD, CAM & 5 axis machining - not manual labour techniques required to rectify parts that could't be machined to the required tolerances on the machines employed in the '50s & '60s

Nigel B

(who has had the privilege of working along side several excellent machine tool fitters, for whom a scraper was an extension of their right arm)

Thread: Need milling tools/cutters
16/01/2017 07:58:15

M10 threaded bar and feed that through the hole in Item 22 thought to the collet and then tighten using a washer and 2 nuts, Would that be ok and if not why not

The drawbar really needs to be a socket head cap screw to get the tool self ejecting function. Item 22 is removed, a washer placed on the exposed end of the spindle & the drawbar inserted, then the cap (Item 22) replaced. The drawbar is now free to rotate, but is axially constrained by the cap - the hole in the end of the cap allows an Allen key to be inserted in the drawbar. When you come to remove the tool, as the drawbar is unscrewed it rises until it contacts Item 22 - further unscrewing of the drawbar forces the tool out of the taper without putting any pressure on the spindle bearings. The thread on Item 22 is finer than the drawbar thread, so even if the cap should come loose as the drawbar is forced against it, the tool is ejected faster than the cap unscrews.

This will not happen if you use a bit of threaded bar & two locknuts. If you want to use this arrangement, remove Item 22 all together & keep in a safe place, then have your "hex bolt" drawbar bear directly on the end of the spindle via a washer. Downside to this arrangement is the need to hit the end of the drawbar with a hammer to release the tool - something the spindle bearings will not thank you for in the longer term.

Joe is a braver soul than I to run such large cutters in an FB2 - the swivelling head is only held with two bolts & I have had my head move under cutting loads with 12mm cutter.

Nigel B

15/01/2017 16:54:02

My Vice, its a 3" one of these **LINK**

Looks OK - one thing less for the shopping list !

Yes, Item 27 is the drawbar & Item 22 is the retaining cap that ejects the tool when you unscrew the drawbar.

Nigel B

Edited By Nigel B on 15/01/2017 16:56:10

15/01/2017 16:32:43

Anyone know what size draw bar I will need for my mill?

The parts list I linked to above shows the factory part was an M10 x 200 Cap screw to DIN912, sitting with a washer against the end of the spindle. The thread you require will depend on the collets you buy - mine were 3/8" BSW & I made a suitable drawbar - I can drag it out & make a sketch if you want ?

We use 3 flute cutters almost exclusively at work. HSS cheaper to replace than carbide when you break one on the learning curve ! Before you send your order off the Arc, what kind of vice have you got ? cheeky

 

Edited By Nigel B on 15/01/2017 16:33:20

Thread: Look what followed me home: ML7 Myford
15/01/2017 14:00:12

ball peen hammer marks on the top of the bed. I kid you not. Thankfully at the tailstock end, on the part the tailstock does not contact.

I bought a very sad Super 7some years ago, mainly to get the screwcutting gearbox cheap. That had similar marks in the same area & I concluded that it was from knocking Morse taper drills into reducing sockets.

Certainly makes the Chinese mini lathes seem like a bargain!

Yes and no - Chinese machine tools are, at face value, very attractive. The Myford product did have the advantage of being supplied useable and to reasonable standards of accuracy, fit and finish straight from the factory. I have always thought of Chinese machines as being a kit of part finished parts, loosely assembled for ease of transport. I wonder how many of these inexpensive Chinese machines will be around in 50 + years time & be as capable as the ML7 / S 7 of being refurbished to provide years of further use ?

Nigel B

Nigel B

15/01/2017 10:36:00

I thought they were a "superior machine".

They were an "affordable" machine, with the "affordability" generated by (for the time & product) innovative mass production techniques and materials to produce a "system" whose functionality exceeded the sum of it's parts .

No point being "superior" if your target audience can't afford to buy the product - something Myford appeared to forget in later years and priced themselves into history. I bought a copy of LH Sparey's gratingly titled "A Man and his lathe" last week, which deals primarily with using the ML7 & was printed during the machine's heyday. There is a comment in one section along the lines of " the machine is so inexpensive you can afford to buy the accessories to expand it's functionality" - how many hobby lathes can you say that about today ?

Nigel B

Thread: Need milling tools/cutters
14/01/2017 15:42:38

Just an edit to the fibre gear comments above - Pro Machine Tools do list the fibre gear as available at £66 each inc. Vat.

**LINK**

The spare parts list is here as a .pdf : **LINK**

Note that the spindle was only available as a complete quill/spindle assembly - no separate bearings listed.

Nigel B

Thread: cz metal bender
14/01/2017 15:12:33

The Groz copy sold by at one time by Axminster is very poorly made from poor quality materials - the steel box mine came in is the best bit of the whole arrangement. If you fancy one of these, I would suggest trying to get a German original - they do come up on Ebay from time to time.

Nigel B

Thread: Myford bearing spacer
14/01/2017 15:07:37

Seeing as winter appears to have arrived, I dug my way into the garage today to find the winter tyres for the car. With that chore out of the way, I had a play with the S7.

As the machine has been stood a while & was very cold, I started slow & ran it through the speeds over 10 mins or so. Then, while running (quietly) at 1020 rpm, I pumped oil into the rear bearings until it flooded out. Absolutely no change in noise level as the oil went in (and came out !) or over the next 10 mins or so running.

I live around 3 miles from Millers Oils head office & buy my oil from their trade counter. I use "Millway 3" - a 46 viscosity slideway oil - for all the oiling points except the screwcutting gearbox, which gets a 68 viscosity slideway oil.

Nigel B

Thread: Need milling tools/cutters
14/01/2017 14:53:55

if you want to use your 20mm cutter

A bit brutal in a small machine with all of 1/4 Hp (if single phase - 1/3 Hp 3 phase) to drive it. That said, Emco did list a shell end mill arbor and a 40 dia. HSS shell end mill as accessories - but this sits a lot closer to the spindle nose than a collet chuck. The collet chuck Emco offered was ESX25, with max. collet capacity of 14mm.

I made an arbor to carry a 50 dia. 3 insert face mill. My S7 came with the taper turning attachment & it is set to turn 2MT tapers. It was straight forward to make the arbor so that the flange was about 0.002" clear of the spindle nose when inserted by hand - when nipped with the drawbar, the flange contacts the spindle nose for increased stiffness. I can't say I am too happy using it, though, and tend to use a fly cutter & light cuts to face larger areas.

As I was in the garage today, I had the drawbar out of my FB2 clone. I made this, as the machine came without - it is approx. 11.5mm diameter, with a 3/8 BSW thread to suit the 2MT collets. It is a loose fit in the spindle, which I didn't measure but would expect to be around 12mm through. At a guess the 8mm drawbar would have applied to the earlier, 4 speed "Mentor" version.

There are also spanner flats on the spindle but the spanner provided is next to useless so make your own.

Yes, the OE pressed steel item is very short - my machine is 32mm AF, a standard metric spanner size. I would not contemplate not using a spanner on the spindle nose when tightening or loosening a tool. I doubt very much that the fibre gear is still available - the owner of my first machine of this type bought replacements from Ajax Machine Tools when they were in Stockport & 20 years ago they were £75 a pop. He reckoned these were cheaper than Emco.

I have an original Emco FB2 brochure & a photocopied FB2 clone manual - I'ii try & get these scanned & pop them in an album as .jpegs when I have a spare half hour.

Nigel B

Thread: Myford bearing spacer
13/01/2017 22:00:32

Too much oil in the rear bearings.

How do you put too much oil in an open bearing ?

Nigel B

13/01/2017 21:41:38

What you describe as a "split collar" is the preload locknut at the end of the spindle. Given that you have changed the bearings and spacer, I doubt that any scribed lines are valid now. Did you look at the link I gave above to the Super 7 Manual - page 26 describes the procedure for adjusting the rear bearings.

Nigel B

13/01/2017 21:07:41

sounds like a tin bucket full of marbles being slung around!

My Super 7 spindle is pretty quiet in direct drive & a bit "growly" in back gear - but only when the feed gearing is disengaged. The gear train is rather rattly when engaged, so I run with it out of engagement unless required.

Have you got the thrust bearings adjusted too tightly (the nut at the LH end of the spindle) ?

Nigel B

Thread: Need milling tools/cutters
13/01/2017 20:58:59

But is that possible?

In Graham's case, unfortunately so - see this earlier topic :

**LINK**

Nigel B

13/01/2017 20:41:11

I use 2MT collets to hold milling cutters in my FB2 clone to minimise the tool projection. Most milling cutters have "standard" shank diameters - 3,6,8,10,12 will cover most eventualities. Mine came from ArcEuroTool **LINK** at a Harrogate show (see earlier post about Arc having a 10% discount offer on at the moment) & have worked well.

Using an ER collet chuck will extend the cutter a long way from the spindle nose (increased possibility of chatter + wear on bearings + eats into available headroom) & ER collets offer a shorter gripping length compared to a Morse taper collet. The FB2 (& clones) have a rather strange spindle bearing arrangement that uses a "sized" needle roller bearing running directly on the hardened spindle & quill directly - there is no adjustment for wear, so it seems preferable to me to reduce the loading on this bearing as much as possible to maximise spindle life.

IIRC Graham Meek has described a reworking of his FB2 spindle to take taper roller bearings, but I don't know where Graham has details of this now since he had all his content on the ME forums removed.

Nigel B

Thread: Advice/Help needed to disassemble ML7 headstock spindle
12/01/2017 07:47:19

when the pulley heated up, which it will do with the friction of the belt.

Only if the belt is slipping - vee belts drive by a wedging action & the belt should not be slipping to cause heat if sound & properly adjusted.

Never had much sucess with poly-vees in industrial applications. They don't need much wear to bottom out in the pulleys & then become inefficient flat belt drives. This may well be due to the way we were trying to use them, with maximum reduction ratios (small drive pulleys) on close centres - but designed & installed according to the belt manufacturer guidelines.

Nigel B

Thread: Myford bearing spacer
12/01/2017 07:38:41

The more open faces should face outwards - pictures from the Myford manual in this thread **LINK**

Nigel B

Thread: Alternative to PC based Cnc controllers
11/01/2017 19:21:30

Do these controllers support servo motors? encoder inputs? tool changers? 4th axis?

The 990T & TAC-1003T are both "open loop" controls that have Step/direction outputs only & no axis feedback provision. There is one analogue output & one encoder input for the spindle. They have a built-in PLC & come with a "standard interface" PLC program that handles a turret (presumably some sort of standard locally produced turret interface), two speed spindle gearbox switching & other, normally expected, functions.

I did find a PLC manual for the 990T, which showed (at a quick read) almost identical functionality as the Fanuc PMC K/L/M used in the 0 series controls (with which I am familiar), with the same signal addresses used (X for inputs, Y for outputs, F & G for NC/PLC communication, R for freely assignable flags/markers etc.), the same command set & function blocks etc. So pretty much any type of functionality that could be achieved with a Fanuc PLC would appear (at first glance) to be available with these - even the processing times (Level 1 program @ 8 ms) are the same. The bigger problem seems to be limited I/O - I didn't find if the 990T could be expanded, but the TAC-1003T mentions additional modules are available to give an extra 16 inputs & 16 outputs - not a lot in the greater scheme of things, but some of the standard I/O could be re-nominated from the as-supplied PLC program if not required.

From an axis drive point of view, Chinese brusheless servo drives seem to have the option of step/direction control as well as analogue speed control as standard. I got a Bonmet 3Nm brushless drive & motor for a project at work that had this. The drive also has outputs for drive error (loss of steps) and a 1 rotation pulse signal derived from the motor feedback encoder - the control has inputs for each axis for these signals, so the control gets to know from the drive if it has stalled & to give more accurate referencing. A sort of "part closed loop-ish" operation, but not the same as a "normal" closed loop on an industrial control. You could also use one of these controls with normal open loop stepper drives, though these would not have the "lost steps" warning or give as accurate referencing.

Still look like an interesting proposition, though.

Nigel B

BTW, the £17 USB CNC board from Ebay didn't turn up within the estimated delivery time (still hasn't) & was refunded. I have yet to get around to ordering another to have a play.

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