Member postings for JohnF

Hi a question for Neil I think, I use Mac but am keen to have a go with this -- I have Turbocad and have never managed to master it --- however I have an old windows laptop so I'll dig it out and check the spec but the question is if I load Alibre onto this using the key and its too slow or ??? can I load it again onto another new PC and still use the key thus having the benefit of the extended trial ?

Regards John

Many years ago a customer of mine who worked at an Unbrako manufacturing plant brought me a quantity of bar ends from auto screw making machines 4"-5" long, he told me they were EN24. The material turned beautifully and was indeed extremely tough when heat treated as you would EN24 from the old ESC spec book.

It would be interesting if anyone can confirm the material spec for Unbrako screws & bolts ?

Any Thoughts ?

Gentlemen, please do not mix incompatible threads and in particular where pressure/stress is involved. Yes they will fit together but they WILL be much weaker.

Threads with different angles will screw together providing they have the same pitch but they will bear on the crest and root and not on the flank thus they will not perform as they should. You are compromising safety.

John

I repeat, the legislation, only applies to the general public. It does not apply to any professional organization or company. I believe the argument is that any tradesman is not at risk but the man in the street is. The former knows what he is doing- the latter doesn't.

 I also wonder how much of the UK housing stock is still on lead pipes -- for sure many of the older properties in our village are still on lead.

Better stock up before its too late ??

Edited By JasonB on 08/11/2018 15:03:59

Not quite what you describe but a similar device look on this link for "spring pins" **LINK**

I searched for "spring clip clevis pin" and came upon this site, hope it helps [didn't look at sizes ]

John

Hi a bit more info here on an older post relating to threads and truncating, mainly used on Whit form when cut by single point where the crest is truncated in place of the radius when a full form tool isn't available.

**LINK**

In particular look at the link by Jon Gibbs on his second post and page 34 in the BS84 standards relating to thread truncation.

Truncated threads were the norm in the aircraft industry in the 60's when many threads on difficult parts were all screwcut rather than with a die box etc. done many hundred's of them.

However as Robert says if the part is subject to high stress its best not to compromise on the root profile !

John

Yes Frank, I'll go and have a look to see if I can refresh my memory -- its several years since I had mine in bits - original Myford days !

Much too far out, better to wrap a piece of paper around your work and re-chuck closer in, paper will protect your work, you loose a modicum of accuracy but for your purpose -- parting off this is immaterial, I find thickish paper or business card type card works well when needed.

Jason explains it perfectly and John Reese is spot on with his comments, congratulations on solving the problem p1h ! However on the video you posted it not quite clear but it looks to me as though you are parting off some way from the chuck ?? how far away are you ?

It certainly looks to be much further than I would recommend and particularly on smaller machines, you need to be as close as possible to the chuck to maximise rigidity, I would suggest a maximum of 1 inch and better closer!

John

petro1head, nothing all wrong with Dickson style tool posts, I have been using them since they first appeared in the early 1960's on many different lathes for DSG, Smart & Brown etc down to my Myford and Emco S11-- never had a problem with my original Dicksons. For parting off I use the bog standard HSS tool in the standard holder on both machines.

However there can be and often are problems with the imported clones particularly if the tool post and holders are from mixed sources. Generally they can be resolved by adjusting the tool holders -- best not to tamper with the tool post unless it is defiantly at fault. Not impossible but unlikely if its genuine one.

I have found some clone holders do not fit and thus lock properly on my original tool posts so have had to modify them. It sounds to me there is something wrong with the locking cam that pulls the tool holder onto the toolpost and would recommend you investigate this first.

John

Why not just contact Boxford I’m sure they will advise, I have always found them very helpful

Try this outfit Gate Machinery seems they took over Elliot machine Co

**LINK**

Might be worth a photo on here and some dimensions !

Edited By JohnF on 03/10/2018 14:08:40

Bill, I have a tin bought xxx? years ago never even new it had a sell by date ? Its absolutely fine and I have never noticed any lack of performance. I would not worry about the date at all.

My guess is its another edict from Brussels, an old pal who processes honey had to apply a best by date to that -- honey is I believe the only foodstuff that does not "go off" it may crystallise but remained edible, no bugs ever grow on honey either.

John

Frank see your messages John

Frank, there is often a small and I do mean small bias in the straightness of lead screws -- we are talking under 0.010" and generally less than 0.005" so don't be too critical. I would replace the dowels at the tailstock end BUT do use ones with a threaded hole for extraction in the future if need be. The thread in mine is 4BA but should you make some form say silver steel any suitable thread will do.

I also removed the compound and cross slide before removing the apron -- take care re- installing the cross slide with the power cross feed, easy to do but make sure you get the key in the gear lined up as you screw in the feed screw.

John

Bricky, are you using the 6 station bed stop ? or a similar "dead" stop? It sounds as though you are and have run the carriage into the stop which is a disaster on this type of traverse -- there are no shear pins or clutches as a fail safe. I made a stop that has a safety feature to prevent this.

If my supposition is correct you will probably have damaged the half nuts and maybe other items ?? hopefully only the nuts which will be Mazak if the same as the earlier machines.

What you need to do first is withdraw the lead screw, to do this [assuming it is the same as the power cross feed S7] first remove the large gear inside the gear train and the banjo etc then withdraw the dowels and screws from the RH end of the leadscrew support bearing -- you need a tool to do this in the form of a miniature puller to extract the dowels. At this point the lead screw can be withdrawn left to right.

When the lead screw has been removed you can remove the apron -- if memory is good ! Then the half nuts can be removed and examined. Replacements are available from Myford

Its pretty obvious what's needed as a puller for the dowels and the thread is I think 6BA but if you need to PM me and I have the details in my workshop -- I need to remove mine some years ago to do some maintenance on the apron.

Hope this helps John

Is there anything in the idea that the keyway in the PCF leadscrew has a "tapping" effect on the half nuts?

Mike and EGA, I purchased my S7 with PCF new about 1977 and its been in use almost every day since then, there is no apparent wear on the cross slide feed at all and minimum backlash so I would deduce this is a fallacy with no substance.

John

Well done Celso great achievement !

John

As V8Eng says I to have tried but struggled to make any headway with Turbocad so lets hope it is for absolute dummy's and tutorials start at very first principals thus assuming the pupil knows NOTHING !

Not even how to draw a straight line !

Shame about the Mac though but can dust off the old Windows 7 PC

The reason for the threaded cutters - Clarkson style - is to prevent the cutter being pulled down form the collet when side cutting or when a deeper cut is applied.

On smaller machine's this is less of a problem but it can still happen particularly if you are using a longer length of the cutter flutes. For most model engineering where smaller cuts and smaller cutters are being used ER collets work very well.

However even on small machines it can and will happen if cutting with larger cutters say 5/8; 3/4" and a fairly deep cut is applied its very possible for the forces to pull the cutter down from an ER collet, this cannot happen with a screw shank Clarkson cutter in a Clarkson chuck.

So just be aware of the limitations of ER collets if you need to remove a fair amount of stock, more smaller cuts are the order f the day -- don't be greedy and try one large cut !

John