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Willy
04-14-2008, 03:00 AM
After reading numerous threads, both here and on other sites, I have noticed a lot of folks avoid the lathe for parting.
I know I used to avoid it like the plague as well and would resort to welding a stub onto short pieces if I could not get them into my bandsaw. I would later bring them to final dimension either in the lathe or milling machine.

Not having the luxury of an insert type parting tool, and being regulated to the typical 3/32 x 1/2 HSS blade in a Aloris style tool holder, I too used to dread parting. So awhile back after have tried every tip, suggested tool bit geometry, and feed rate, I finally achieved parting nirvana.

I'm sure we all know that a little 3/32 bit sticking out over a 1/2 inch isn't going to be very stable when asked to make a cut into a rotating shaft, and therein lies the problem, how to quell the vibration to stop the chatter.

So here is what I did to give the blade the much needed support it so desperately needs...I just put a little tension on the carriage hand wheel and it cuts tootsie roll swarf all day long! No chatter at all, once I'm into the cut about .030, a small amount of tension on the carriage hand wheel and I can keep cranking the cross slide till it's done.

Not sure if this is kosher or not, but it sure works for me. The only side effect I've noticed is that on say a 1-1 1/2 inch shaft I end up having it being slightly convex or concave by about .010 depending on which side I lean on.

I don't think that I am the first to use this technique, are others using this method?
Thoughts?

GrahamC
04-14-2008, 07:39 AM
I have never had issues with parting unless I try and take too big a bit too quickly. I always use the lowest speed, lots of cutting oil and lock the carriage in place.

That said, I think what you are doing by your description of applying a little pressure to carriage is to force the cutter to cut a slightly ever widening slot that in itself helps provide some relief to the parting operation. Interesting idea and I will have to give a try.

cheers, Graham in Ottawa

Willy
04-14-2008, 08:01 AM
I believe the main benefit of the pressure that I am applying is that it supports one side of the blade, so that it is not allowed to act as a tuning fork. The cut does not get that much wider, perhaps .010 concave or convex at the most on a 1 1/2" shaft

macona
04-14-2008, 01:19 PM
It really depends on the machine you are trying to part on. My cheap machines never parted well, even dousing the cutter in sulfur cutting oil, which did help. Once I got my 10EE I have not had a problem, even parting titanium and hardened steel.

Machine rigidity is paramount to parting. Power feed is also helpful. Keeps consistent pressure on the tool.

firbikrhd1
04-14-2008, 09:12 PM
No doubt machine rigidity plays a huge part. Holding the work as close as possible to the chuck helps in that area. Interesting thing though; I was having trouble parting on my 10" Logan until I found a Spring Type parting tool holder. It's much like a regular parting tool holder with a slot cut vertically behind the area that holds the cutter bit. This is an old school holder, no special carbide blade, just high speed steel. No problems parting since. I even use power cross feed, slowest speed in back gear unless it aluminum, then I speed it up some. I keep the feed fast enough to make nice curls of metal rolling up on top of the bit. Lots of cutting oil or WD 40 for aluminum. It's slow but absolutely no chatter.

Weston Bye
04-14-2008, 09:29 PM
Never could do a decent parting job on my Atlas 6", but my Sherline is up to parting with a .086" wide blade, dry, up to 3/4" deep, little or no chatter, homemade blade holder. Oh, only with aluminum, brass or CRS.

JRouche
04-14-2008, 09:36 PM
Hey Willy, thanks for the tip. Next time Im cutting on the SB with the small blade Ill definitely give her a try, Im always looking for nirvana.. Thanks, JR

Willy
04-14-2008, 10:33 PM
Thanks for all the comments guys. Yes I know rigidity is the key to chatter less parting, but short of welding two thousand pounds onto my lathe it still won't have the mass of a 10EE, never mind the rigidity in the right places.
I've always locked everything up that didn't have to move, slobbered on lots of sulfur based cutting oil, and honed my HSS blade to a razors edge, and I used to achieve only mediocre results.
But since I stumbled onto this new technique a few months ago I have almost looked forward to parting off.
No more clamping every unused axis down, and I can usually run dry if I want.
Now I must admit I have not tried this on a wide variety of materials, mostly hydraulic cylinder shafting once I cut through the hard chrome surface with carbide.
It isn't very often that I blaze a new trail in the machining world.
Come to think of it...I've never been a pioneer in the machinist world!:D
Surely someone else has tried this technique?

darryl
04-15-2008, 12:06 AM
I seldom part off in the lathe because it doesn't work that well for me. It's better if I bypass the compound and mount the holder directly to the crosslide table.

Actually, I don't think I've tried parting since I added the spring loaded roller to the back of the carriage to keep it in contact with the rear way. I'll have to do some experimenting now.

Willy
04-15-2008, 12:34 AM
I forgot to mention for those that want to give this a try, I went dead slow as far as rpm goes.
Probably 40-50 rpm, hand feed till it feels right, nice curls come off, lathe not working hard at all.
Hard to explain but I'm sure you've all got a purty good handle on what I mean.
Let me know how you make out.

torker
04-15-2008, 12:42 AM
but short of welding two thousand pounds onto my lathe
OK.. You know that just turns my crank! I like that idea... of course :D
I'll try your idea if I get chatter again.
I haven't had a problem since I started grinding a... ah shucks.. I'm told it's not a chipbreaker so I don't know what to call it now.
How bout a little hook... that curls the chip up.. sorta like a chipbreaker does at the wrong rpm ;)
Russ

Willy
04-15-2008, 01:00 AM
Yeah, thanks for mentioning the little "chip curler", for lack of a better term Russ.
I did use that before with limited suckcess.
I dunno, maybe the moon is just in the right spot or sumpthin, but for the first time in a long while I can do no wrong parting, no other changes to anything but the slight side pressure to the blade against the workpiece.

kevindsingleton
04-15-2008, 10:36 AM
I lock the carriage and apply the side pressure with the compound, and it definitely improves the procedure. I use a 3/32" HSS T-shaped cutoff blade in an Aloris-type holder, and it works better than other methods I've tried. Still, it's pucker-city, all the way, every time I part anything stronger than brass or aluminum. My least-favorite part of lathe work is parting off.

mototed
04-15-2008, 02:38 PM
Read a tip here a few years ago about using a old carbide tipped circular saw blade. Take an old dull one from the 7 1/4" wood saw (too dull for wood anyway) off to the bandsaw to slice up some teeth to fit parting holder and they cut metal like crazy. Now and then a carbide tooth will break, but you can cut out about 14 from a 24 tooth blade. They do have a pitch so they will not cut to a square shoulder though. Whoever in this board that wrote that tip - Thanks, it ended my parting problems and in a rather cheapskate fashion.

Norman Atkinson
04-15-2008, 03:03 PM
Fairly recently, I wrote my bit about parting off. After all, parting off is an everyday job in a professional work place. We, if I am not mistaken, are Home Shop Machinists with a titchy little lathe in a shed with the ball handles increasing the sales of Preparation H as lathe, me and the milldrill drill are in close harmony-well, company!
If you are in the professional category - you ain't got problems.Go put on the coffee, scold the kids and write reams in the other channel about the Chinese.
Parting off in a titchy lathe was a problem which was solved about 50 years ago - or even longer. The titchy lathe got a rear tool post and whilst the lathe continued to run forwards, the cutting tool was inverted. A brilliant piece of invention was that Torker's 'hooky bit' ( sorry Russ) could be a straight top but angled at 7 degrees. Another bit of British brilliance found that grinding a internal vee would narrow the continuous ribbon coming off the tool- because it could be belted along at a fair old rate of knots. None of this mamby pamby go slow thing- with power steering or whatever non titchy lathes have. Stick the tool and it's got to be a 1/16th, out a full inch and a 2" round can be severed like Ghurka soldier slicing an Afghan head off on a dark night.

So, gents, it's all in the book. Polish the old Newcatle Brown Ale beer bottle bottoms and see what the other half on this side of the pond are doing.

( Shhhhh, you're not going to let an old cranky fart like me with an even crankier worn out mangle of a lathe beat you, are you? And I am NOT even an engineer)

Oops, more trubble at' mill, lads!

Norm

small.planes
04-15-2008, 04:38 PM
I made a parting off tool for my unimat using a circular saw tooth abotu 3 or 4 years ago. Not sure why you only get 14 out of a 24 tooth blade, I get 24. Once you have the blade 'blank' cut correct just unbraze the tip when it breaks and braze a new one on. You get about 12 'LH' and 12 'RH' tips on a 24 tooth blade. I made a small carbide boring bar with one, cuts beautifully (really pointy), and I made a LH and RH turning tool as well. Seems I use a lot of these, but I lucked into a pair of new carbide tipped blades in the bargain bin at a DIY shed, 50p each (about $1 ea)

Dave

oldtiffie
04-15-2008, 08:42 PM
If I recall correctly, it was John Stevenson who suggested and showed the use of a (say) 1" wide strip cut from a TC wood saw-blade with a single TC tooth on the end and "tilted" at about 45 degree with the required back-rake and front clearance obtained from the tooth as a cutter.

I have been trying to a long time to find a similar item that was in use over 50 years ago as a TC parting-off tool.

The "strip" was about 1 1/4" x 3/16" held at a vertical angle of aboput 45 degree in a tool-holder in the tool-post. The TC tip was on the end. It was exactly the same principle as John used with his "saw blade". They were very "stiff"/strong in the vertical plane and would take all you could give them and just needed a "touch-up" on a "green" or diamond wheel. They would cut just about anything and could cut (as I recall) about 2" or more deep. Sure, the better the lathe the better the job/cut, but they worked very well on a "medium" or small(er) lathe as well.

Best I have ever seen - but I can't find them now.

Can anybody suggest or advise a source please?

Willy
04-16-2008, 01:30 AM
I lock the carriage and apply the side pressure with the compound, and it definitely improves the procedure.

Kevin I'm glad to see that I'm not the only one to find some benefit out of this procedure. For awhile I thought I was the only one here to find it beneficial.

However lots of other interesting ideas here too, I had forgotten about the carbide circular saw teeth as cutoff tools.

You know it still strikes me as funny that the wood working guys use carbide to cut wood, and for the most part we cut metal with steel.

Norman Atkinson
04-16-2008, 03:34 AM
Greetings, OldTiff!

Great minds think alike or are we just plain old and seen it all.
My mind is quite clear about the use of carbide saw blades and it did get an entry into Model Engineer 50 years back! When and how and what, I haven't a clue because recovering a bit of carbide and 'fannying on' sticking it all back again sounds a bit like the old Services song about 'Hands in pockets and F***All to do'

As it stands, we have one guy with a plain- non screwcutting lathe and is doing all sorts of wondrous things on a Unimat. Now in a fit of almost forgotten insanity or mental aberation, I had a SL100. My thoughts on such a thing are largely unprintable but any lathe with half inch bed bars and plastic gibs deserves a medal for sheer( pardon, shear) lunacy.What gives with a guy who mixes carbide and a 'Willy Wonker' In the same context, 50 or whatever years ago, do you recall a 'Getting the most out of a Unimat' and written by a guy who , like me, was 'educated in the uncertain days of the war'? Again, I recall( Rex Tingey?) beefing up the whole caboodle- cos it was crap.
So let's move on( I'm in grumpy mode) Carbide saw tips are 'handed'. Whether they are still brazed and not welded, I know not or care not, but I have a 'chitty' in a forgotten drawer to say that I am a Certified Welder.
One thing is certain, there is more things in life than regrinding a saw blade insert so that the cutting face will not wander.

Anyway, old son, that is my thoughts on parting off.
The late George H Thomas( an equally cantankerous old turd) wrote page after page on parting off. It is all contained in his excellent Model Engineers Workshop Manual. My memory does suggest that it was Volume 142 in Model Engineer and I guess that it was 1973. GHT refers to developing Ian Bradley's original castings of 45 years earlier.Bradley wrote as Duplex as part of his association with Norman F Hallows.


Just for a bit of light hearted stuff, there was a Brit in the early 50's who could part off 4" square in a 7" swing lathe faster than he could with a machine hacksaw.

So, if anyone wants to re-invent the wheel, they are free to try.
For myself, I can only suggest that somebody invents something to get information to the other side of the Pond!

Exits- the Grumpy Old Fart!

small.planes
04-16-2008, 03:39 AM
For myself, I can only suggest that somebody invents something to get information to the other side of the Pond!

Exits- the Grumpy Old Fart!

I thought that was called the internet :p :D

Dave

kevindsingleton
04-16-2008, 08:35 AM
Willy,

Wood butchering is done at much higher rates of speed. I only wish I could remove metal as fast as wood, but without giving up the accuracy! I've used the carbide saw blade trick, too, and it works well, but I'm running out of table saw blades, with lots of dead tree projects yet to complete!

I parted off some 1 1/4" 416 stainless with a T-shaped HSS parting tool, yesterday, and it was nerve-wracking. Fortunately, it was bored to about half its diameter, so it was over with, quickly, but it still gives me the ...say it with me ...Willys!

Edited to clarify size of stick!!!

Norman Atkinson
04-16-2008, 09:53 AM
!/4" Stainless with a hole in its middle. Stand back in amazement!

We have to learn something everyday. Is this it?

Norm

Willy
04-16-2008, 10:19 AM
Norm, I believe Kevin mentioned 1 1/4 inch 416 stainless, not 1/4 inch.

Norm, also rather than berate and belittle, why don't you do a small dissertation on parting off techniques. I'm sure given the interest shown whenever the subject arises, that it would be most welcome.

The satisfaction will then be yours alone, having educated the great unwashed on this side of the pond.

Norman Atkinson
04-16-2008, 02:10 PM
Willy,
One reaches a point in life when the decision comes of 'What the Hell?'
I most assuredly have repeated myself- ad nauseum.
If you re-read my comments, you will find that I didn't write the originals on 'Parting Off' but deliberately pointed out where the information is- and has been since 1973 or 45 years earlier than that. That information is copyright.However, the cost of accessing the information is less than $60 plus postage. You can, however, get a fair idea if you access Hemingwaykits who supply castings etc for Thomas's accessories.

I have made much effort in the past to get releases of material for what I sincerely believe would help the less experienced. What you must remember is that I was less experienced- but the important thing is that equally grumpy old men imparted what they knew to me. If you want information, you cannot be too fussy about what is being given- or how it is given!

Before you jump to conclusions, just think that there is an old man who had to survive by taking the detonators out of firebombs with only the light of the burning ones. I , sir, was all of eleven years. It's called 'On the job training now', I was simply with an old sapper from another war.
Unless the fires went out, there would have been another 7 HE and a ticking bomb . Oh, I forgot to mention that there was 500 lbs of explosive running its course.

Well now? You have a story of your boyhood. Your Turn?

Willy
04-16-2008, 03:46 PM
Well now? You have a story of your boyhood. Your Turn?

Norm, I'm here to exchange ideas, information, and techniques as it relates to metal working.
I am not here to go toe to toe with anyone in a verbal diatribe as it does not interest me in the slightest.
If on occasion I can assist someone with my previous experience in a certain subject, I am more than happy to help. If on the other hand I cannot help but am interested in the thread I'll read it and learn from it what I can. If I am not interested in the title of a post, I do not even bother opening it. This simple yet effective strategy has always worked for me.

However I do not criticize without at least giving some constructive advice. I don't believe anyone here was born with machining knowledge, we all have to learn from someone, that's why we are here, to learn from one another.

Norm, believe me I have the utmost respect for your experiences, both during WWII and after. I am sure you have much knowledge to share. But rudeness in the guise of a grumpy old fart is not very becoming.

For what it's worth Norm, the jungles of Viet Nam in the sixties were not exactly the most hospitable places to go camping either.

Norman Atkinson
04-16-2008, 06:02 PM
Willy,
Well all you have to do is put your hand in your pocket.
After all do you really trust the advice of someone who left school at the age of 14 after 5 years of war on his doorstep?

Oh, I have yet to ask anyone here for assistance! I may not know all the answers- but I know where to look.

Have a nice day

Norm

Willy
04-16-2008, 06:41 PM
Willy,

After all do you really trust the advice of someone who left school at the age of 14 after 5 years of war on his doorstep?
Norm

Norm, yes those are exactly the people that I trust for advice.

I'm sure that the CEO of GM does not know how to build a car either...but he is smart enough to surround himself with those that do.

If I don't find an answer that works for me here I look elsewhere. But a lot of experience resides here, so this is my first source. Right or wrong I trust the past experiences of others that have more knowledge in fields than I.

Have a good one Norm,

Willy

oldtiffie
04-16-2008, 07:22 PM
It happens often enough:

"Parting is such sweet sorrow" - "Romeo and Juliet" - Shakespeare.
http://www.enotes.com/shakespeare-quotes/good-night-good-night-parting-such-sweet-sorrow

And when it all goes wrong:
"Loves Labour Lost" - Shakespeare.
http://en.wikipedia.org/wiki/Love's_Labour's_Lost

And where it goes when you "lose it":

"Inferno"
(from Dante's "Divine Comedy)
http://en.wikipedia.org/wiki/Divine_Comedy

Quite an education in the shop - ain't it? And all from old works and old men from "over the pond" (UK) - just as Norm sez!!!

Ya can't beat this turning caper can ya?

And the reason dogs turn twice before they settle down? - one good turn deserves another!!

Norman Atkinson
04-17-2008, 04:01 AM
Thanks, Tiffie!
I even did the French- Le Partage des Eaux.
Not quite refering to where the water flows both North and to the South but to the amount of soluble water needed in a parting operation.

With impish Gallic charm, I could have changed the sexes( coo!) and had Le Tour de France( which is a cycle race) and La Tour D'Eiffel which is that thing that sticks up( coo!) in the centre of Paris. Tour being the same for a tower, a journey( journe- being a day) and tour being a lathe.

After all, I am a French Mon Sewer- and always in the Merde- the Mer de Glace.

Enough of this frivolite, for I am reading Wordsworth and 'The winds cometo me from the fields of sleep' and my prostrate is making my rheumy eyes to water.

Sleep well, fair Prince

Norm

( Not bad for a kid who left school at 14, eh?_

John Stevenson
04-17-2008, 04:12 AM
Norman,

North of Newcastle next week on another install.
Any chance of a cuppa ??

.

Norman Atkinson
04-17-2008, 04:37 AM
Monday- Oriental Royal Arch Chapter No 9371 then Palace Garden Restaurant

Then to Aviemore for the rest of the week.Just got in from France very late last week. My neighbour in the adjoining semi- cottage left his water on over the winter. ( we had drained ours out) He had got the huge temperature drop and when the thaw finally came, the water was running from several bursts.
His ceilings have come down- and we don't know whether the water has come through the adjoining wall. My actual damage was a stuck cold water valve but we haven't a clue about secondary stuff.

So, my friend, bang goes our meeting up. I would have liked to show you my 'new' Stent. Again, Harrogate is off. If the place is OK, I have to garden , ready for summer. Then, it's the Boss's 70th and we are going over to Menorca. The car there is to tax and insure, the bank accounts are to top up there and I have to paint the bloody place. Oh, and I have a strange bank debit and suspect that my pool manager has done a flit.

( and that, dear John, is the abbreviated version)

Oh, it would have been great!

Norm

oldtiffie
04-17-2008, 06:09 AM
Hi Norm.

To get things done quicker - catch the Orient Express.

The mind boggles thinking of John S doing your Installation - not of stent.

You've been poor and penniless before - just give freely and take it easy.

I rather thought you'd be in the squares and levels discussions (2) recently - why not?

In keeping with the title of the thread ie "A parting thought": "Auld Lang Syne" (Robbie Burns)
http://en.wikipedia.org/wiki/Auld_Lang_Syne

Anyway - I hope that all goes well.

Norman Atkinson
04-17-2008, 07:53 AM
All Good Engineering stuff to be done in degrees!
For Orient Express read 'Emirates' cos I got to HongKong to meet up with the local lads but the Scots and the Irish and the OZ who had come in specially--- for the Installation of the new master of HK's University Lodge- who is our master of the Oriental Lodge in Newcastle(upon Tyne). Can't get in the Lodge bit but I get invites. It's tough old game trying to get through 16 courses at the banquets. Tonight, I have to get the old sword out. Would I come as a guest to the Reserve Forces Lodge and iron me mess kit, blanco me great coat and wear my masonic 'pinny' and get stuck into the port.Toast Queenie, do the mystic signs and listen to a nice old geyser who 'went in' before D Day. All of this is prefaced by 'I say Chaps, Good Show, old boy and there goes the little bastard, tally ho, wot, wot?'
Funny thing, they won't let me in- officially cos, I refused my commision in the field- and got more money as a corporal.

I now expect to be getting an invite to join the Scottish mob. One thing, old son, it is ruining my sylph like figure.

Question, sir, do I tell this American chappie how to part off with a sword or a pig sticker bayonet.

Happy have we met and and all that sort of thing

Norm

Paul Alciatore
04-17-2008, 12:32 PM
I don't know if this thread could or even should be steered back to thoughts about machine shop parting, but I have one so here goes.

Willy's comment about side pressure helping triggered some thoughts in my hollow upper appendage. I have tried grinding a small angle on the tips of the standard, narrow parting blades. Just about 15 degrees or so from the standard flat tip that seems to be recommended by most sources. It seems to help. I am now wondering if this slight angle is forcing the blade against one side of the cut and stabilizing it in the same manner as the pressure on the carriage handwheel does. I ususlly angle the tip to cut off on the side of the part first as a small cone will be left on one side or the other with this kind of grind. I also tend to get a slightly concave or convex cut with this technique, but most parts can tolerate this.

I am just wondering if anyone else has tried this.

kevindsingleton
04-17-2008, 04:08 PM
That's what you'll get using the pieces of carbide circular saw blades as parting tools, if you don't grind them flat on the cutting edge. The teeth are ground left and right, so you pick the one that gives you the end result you want. You can see the blade bending into the cut, as it gets deeper, and I usually take up some of this bend with the compound, if possible. I also use a 1/4 inch wide HSS toolbit ground to about 1/8 inch, with a square cutting edge and a smooth, wide, curved chip breaker ground into the top. It works well for brass and aluminum, at higher speeds than I'm comfortable with when parting steel.

oldtiffie
04-17-2008, 07:22 PM
Putting a say 5>10 deg bevel on the front edge of a parting tool was common practice. The idea being that the right corner leading would cause the work to be parted off cleanly leaving the small tapered ring behind to be finished off by the parting tool without it being stuck on the back of the parted off work.

If the bevel was too large or the parting tool was too long or thin the tool would tend to move to the right to follow the "slant". That was OK as most times the parted off face on the work would be finished/faced/cleaned-up in a later process.

FWIW it works very well and often-times the parting-off is better than using a tool with a "square/flat" front face or cutting edge.

Norman Atkinson
04-18-2008, 03:28 AM
I feel that in deference to others who may be unduly influenced by the very weird thoughts expressed here, a word or two more is needed.

The first comment is that many readers will not have the facility to remove a few saw teeth and secondly, fit them onto a holder and thirdly, grind them and then hone them to a new suitability of purpose. Even discussing the few points here, assumes a lot of tooling.There is Quixotic situation of being able to afford all this tooling but are too skint or mean to pay out for what is one of simplest and commonest practices in engineering.
I have no idea what a single 3/32" by 1/2" HSS blade costs now but but it is going to be less than the gas and brazing/silver solder and a greengrit wheel and diamond paste and I have ignored the initial costs of the swag to use them.

For part of the initial outlay one needs a tool and cutter grinder.The American Forum here has written long and hard about a cheap jack solution of how to get something decent. I have to say that I was part of the discussion as I have bought and and made a succession of this tooling.
In addition, OldTiffie has added his invaluable contributions- and whilst we pull each others legs, we are very, very serious workmen with long long experiences.

So, might I ask you yet again to read up what is written. If you know better, then it is up to you all whether you are willing to impart and better what is already known.

Norm

small.planes
04-18-2008, 03:59 AM
Norm,
removing and rebrazing carbide is 'just' a normal brazing job, nothing more special than a normal gas torch, flux and rods required. I use a propane one, as thats what I have. I made the parting off tool for the unimat because the available tooling for that size machine was (still is?) rubbish. The tools available at the time (and I bought one that I now dont use) use a tiny HSS blade, and a sort of split clamp arangement that doesnt work in those sizes. My sawblade tool is full height (crossslide to center height) and bolts to the side of a block of steel. Much better :)
Fitting new tips is admittedly tricky, but practice at brazing is a good thing, and the costs are not that big (I was given some rods by a fabshop that was having a clear out). I have not needed to grind the tips, just use them as is. This does mean the brazing position is more critical, but loses a whole set of tooling (I have no green grit wheel). I occasionally touch them up with a cheap diamond plate (about 4 or 5 IIRC - usual oilstone sized).
As for the LH/RH turning tool I made (For a harrison L5, not the unimat), it was done at a time when I had the items to make it and needed a carbide tool to turn some perticularly hard steel (IIRC a 25mm 12.9 bolt I picked up from the scrap in the generator install section). I *could* have bought a tool, waited for delivery, faffed about setting it up to center height etc. but instead I spent about 1/2 hour in the shop making one from some scrap steel. It did the job wonderfully, and allowed me to do it then, rather than 5 days hence...

obviously YMMV, and Im a beginner at all this really (just about 5 years).

Dave

Swarf&Sparks
04-18-2008, 06:12 AM
Norm, to be fair, I think that the poster suggesting carbide, cut sectors from a cheap TCT woodworking blade.

I used to use donkey-saw (power hacksaw) blades, myself. Broken blades were available from a mate of mine. He's since sold the business :( So I may have to try the TCT blade idea.

A second point is, I made an "agricultural" rear tool holder, purely for parting. I did not require a brilliant finish, nor close tolerance. The rear tool holder though, was worth it's weight in single malt :D

Norman Atkinson
04-18-2008, 07:48 AM
S and S,
Initially, I am glad that you have discovered the advantages of a rear tool post. I was trying to go further and remark that the guy who wrote the parting thing was parting off 2" MS discs on a 7" swing model lathe to an accuracy of 2/10ths of a thous parallel. Again, these were to an exhibition finish!

Refering to Dave( Small Planes), he also drew up a set of miniature parting and screwcutting tools in HSS for small work such as can be done on the unimat. Coming back to 5 years experience, I was going over my wicked past and noted that it is 59 years on monday since I was in charge of 3 technical sections and was all of 18.It is salutory to think that the other boys on the RAF station were mending Spitfires and such. Of course, they hadn't 5 years experience. They had received all of 6 weeks! For my pains, I didn't have such a luxury of 6 weeks or any at all. However, It's the Queens Birthday on Monday. My Squadron will be up escorting the old Battle of Britain Memorial Flight. The 59 year old DH Devon that served the flight has been pensioned off but is still fully operational. It was one of ours. There are two more in the RAF Myseum and with my Antarctic Austers and Johnnie, my mate's Spitfire is still there. 5 years, dear me, Dave, we only took 6 to start and and finish a war!

Have things changed since? Maybe I am just as jaundiced as back then staring into the burnt sightless eyes of my comrades that day but more shakey on my old undercarriage!

Life was like that

Norm

Swarf&Sparks
04-18-2008, 07:52 AM
Norm, with ANZAC day coming up, I salute you and your ilk.
Sincerely, Lin.

John Stevenson
04-18-2008, 07:54 AM
I have never parted off a spitfire.

..

ahidley
04-18-2008, 08:01 AM
Its all here last post

http://bbs.homeshopmachinist.net/showthread.php?t=24821&page=2&highlight=parting

And yes you need to square the carbide teeth or it'll walk sideways.

Norman Atkinson
04-18-2008, 08:41 AM
Never in the field of human conflict have so many written so much to what is so little.

Ooops, Why where they born so beautiful
Why were they born at all
They are no bloody use to anyone
Why where they born at all?

And John, you built Spitfire engines. Boys with 6 weeks experience had to keep them going- long before even you got round to it. Oddly, I recall my cousin parting off bits for Merlins- and she was a SHE.

I was talking to a Trenchard's Brat the other week. He was describing scraping in a set of Merlin main bearings and lining up. He might have had more rings round his sleeve than he had round his arse but a Trenchard's Brat is a RAF Boy Entrant.



Norm

John Stevenson
04-18-2008, 09:54 AM
You don't scrape in Merlin main bearings, they are line bored by hand with shell reamers and a bloody great wooden tap wrench wot looks like a propellor.

.

Norman Atkinson
04-18-2008, 04:52 PM
John,
are you talking about the fellow with a pointed hat and a wand with sparks coming out of it or the locomotives/

I always knew about the Merlin which was a King Arthur Class locomotive but maybe there is confusion about the Hurricane 2C which was a tank buster and the saddle tank locomtive called Merlin. The 2C, I am reliable informed got aluminium bearings made on site in the Western Desert.These locomotives- did they have Stephenson's Gears?

You must be getting on to have done all this stuff.

Err Cheers- and that.( and fellas, this is all actual stuff)

Norm

He did say that he made Tank Engines!