Member postings for Swarf, Mostly!

Hi there, all,

I have a Dickson-style tool-post on my ML7, it's branded 'Elliot' and I think it originally came off a Maximat V10-P.

I have several tool-holders for it, some of which fit well and some of which do not. These are from various makers/suppliers. The holders which came with the tool-post fit OK as do those I bought more recently from A&R Precision.

I find it somewhat very frustrating that many people offering tool-holders for sale do not give any dimensional information.

In researching this topic, I've found three tables of dimensions, one on Lathes.co.uk, one on the Rotagrip web-site and one in the MSC/J&L Tools' 'Big Book'. However, none of these tables of dimensions specify what I think is the crucial parameter i.e. the distance between the Vees (see the photo in Richard Green's post, above). Measuring that parameter is not aided by the fact that some male vees are flat-topped while some of the female vees are flat-bottomed.

One of the top items on my 'to-do' list is to find a pair of dowels and to measure the Vee-pitch on all my tool-holders - the emergence of this thread motivates me to do so sooner rather than later.

I shall be following this thread with interest.

Best regards,

Swarf, Mostly!

Hi there,

The explanation for what you have found depends a bit upon which thread form is involved.

If, say, your tap is to cut metric thread form, the male screw OD is the nominal OD but the female thread (i.e. the nut) has clearance to ensure it clears the crests of the male screw. In order to cut this clearance, the tap diameter has to exceed, by a small amount (* see below) the nominal OD of the thread.

Before posting this, I consulted Tubal Cain's 'Model Engineers Handbook', pages 57 & 58. He shows the profiles for both nut and bolt for several thread forms. His diagrams show the matter more clearly for metric threads than for, say, Whitworth form but there has to be crest clearance built in to the standard somewhere.

What you have found often goes un-noticed because of the difficulty of measuring the OD of a three-flute tap whereas your tap is four-flute where the OD is more easily measured.

I had the same experience when I made a drilling/tapping jig to put the 1/4" BSF screw-holes in the side of my ML7 bed to accept the fixing screws for the quick-change gear-box. I carefully drilled the holes in the tapping jig 1/4" only to find I had to open them up to let the tap enter.

I recommend Tubal Cain's book but I'm sure there are lots of charts of screw-thread profiles on the web.

I hope this helps.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 24/05/2016 21:16:54

Hi there, Nigel,

I'm not challenging the point you made but wouldn't it also apply to the plating of bolts in original manufacture? Is that 'secondary heat treatment' part of the manufacturing process?

Best regards,

Swarf, Mostly!

Yes, I saw that, but you didn't say whereabouts the magnet is situated. I posted in haste so, I'm afraid, I didn't make my point clearly enough! It was that having the magnet on the drain plug is advantageous.

Best regards,

Swarf, Mostly!

Hi there, Nick and Clive,

When I had a BMC Mini I bought a replacement sump plug fitted with a magnet. They might still be available - try your local 'go faster' shop.

Best regards,

Swarf, Mostly!

Hi there, Tim,

You don't say how you're fitting the collet into the chuck - the correct way is to 'click' the collet into the closing nut first, then engage the nut with the thread on the chuck a turn or two, insert the tool and tighten. (Having cleaned everything first, as others have said.)

If you insert the collet into the chuck while still separate from the closing nut and then screw on the closing nut and tighten, the nut will bear on the collet asymmetrically and throw it out of alignment. Well maybe 'throw' isn't the right word, perhaps I should have written 'bias'.

Best regards,

Swarf, Mostly!

Congratulations, an enviable prospect!

Just a tip, though - avoid using the word 'workshop' in your planning application paperwork. Call it a 'hobby room' and say it's for 'hobby and domestic storage purposes'. If you use the word 'workshop' the planning people and/or the council members will immediately have mental images of loud and cataclysmic noises 24/7 and spray paint over-blow wafting over the fence onto the neighbours' washing.

Best regards,

Swarf, Mostly!

Surely this arrangement is quite common (standard, even!) in pillar drills?

Certainly my Tauco works that way.

Best regards,

Swarf, Mostly!

Hi there, Jason,

People who've got space for a milling machine AND who've got a milling machine in that space shouldn't be blaming anyone for anything - they should be spending all their time usefully enjoying that facility!

So there!!!!!!!!!!!!!!!!!!

Best regards,

Swarf, Mostly!

I drive a Citroen - would LHM do?

Best regards,

Swarf, Mostly!

Hi there, Daniel,

Please check your PM inbox.

Best regards,

Swarf, Mostly!

Hi there, Daniel,

Have you resolved your problem with the Derotor?

I have an identical motor, complete with foot control and flexible shaft - my late wife used to use it for her hobby of glass engraving. When I tried the motor recently it tripped the domestic earth leakage trip. I have tested both the motor and the foot control unit with a Megger and I'm getting 5 Megohms from both phase and neutral to 'earth'. The brushes still have lots to go and there's no evidence of carbon dust.

I explored the maker's web-site but they seem to have migrated their 'core business'.

I'd be grateful to hear exactly what component (supplier & part number) you've used and whether it solved the problem.

Best regards,

Swarf, Mostly!

I don't want to be on the same Internet as you, let alone the same forum!!

Best Regards, So there,

Swarf, Mostly!

Edited By Swarf, Mostly! on 23/02/2016 18:50:13

'Nickel silver, Mailechort, German silver, Argentan, new silver, nickel brass, albata, alpacca, or electrum is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc. Nickel silver is named for its silvery appearance, but it contains no elemental silver unless plated.'

Best regards,

Swarf, Mostly!

Perhaps its partner is 4' 8½" further down???

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 19/02/2016 22:08:44

Hi there, all,

I bought my ML7, second hand, in 1970. While I have not been an intensive user, the only problems I have encountered with it have eventually proven to be between the operator's ears!!

Best regards,

Swarf, Mostly!

Hi there, Nick,

From my armchair, it looks as though the device would work better with a female centre and a ball-bearing. Ditto at the head-stock end.

Best regards,

Swarf, Mostly!

Hi there, John,

I'm pleased to read that you've made progress. I wouldn't be surprised if, with a bit of practice, you'll be able to even improve on one thou.

I endorse Nick_G's comment regarding the Griptru chucks - they seem to command about twice the price of a standard three jaw of the same size! So, if your workshop is a garden shed, take it ( i.e. the Griptru ) indoors each evening and stow it under the bed overnight!!

Best regards,

Swarf, Mostly!

Hi there, again, John,

I suggest that you have a look at this web-site: http://www.600uk.com/products/machine.asp?id=150 

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 01/02/2016 16:33:56

Hi there, John,

You wrote 'Pratt Burnerd tru grip', did you mean 'Pratt Burnerd "Griptru"'?

If so, the Griptru chuck is adjustable to eliminate run-out. I guess you have to perform the adjustment every time you change to a different diameter work-piece.

The instructions should be on the web somewhere (probably lots of 'somewheres'! ). I'm sure there will be members here who can advise.

Best regards,

Swarf, Mostly!