S&B Sabel lathe quick change tool post

[gerry45Participant @gerry45]

Hi,

I Have a Smart and Brown Sabel lathe which i rebuilt during the covid lockdown. Since then i have moved house and have have just got around to sorting the problems i found.

Dealt with the backlash on the cross feed but now need to change the tool post for a quick change type. It currently has a four sided tool post which when removed from the post has the remains of a rachet. The post that clamps the tool holder is 1inch diameter has a nut at the top to clamp it into the cross slide and a tightening handle which screws on top. What quick change tool set do i need to find / purchase that will fit the lathe? Not familiar with some terminology so please be gentle. I can take pictures of what is there at the moment with dimensions if necessary.

Thank you.

[Clive FosterParticipant @clivefoster55965]

Gerry

The official accessory quick change toolpost would almost certainly have been a Dickson type size S1 able to take up to 3/4″ shank tooling. A good quality clone should be be just fine but low end imports have a history of problems. Given the need for security and the inevitable necessity of the tool tip divining its support at significant distance a QC post is very much not the place to skimp on quality. Check the sizes before purchasing using this link.

https://www.lathes.co.uk/latheparts/page13.html

As the two parts of the T slot in the cross slide are a close match to stock bar sections the large T nut needed to hold the tool post down can be made from two sections of steel bar screwed and glued together. The nut must be at least as wide as the tool post, ideally full width of the top-slide top, if the post is to be held down properly without distorting the topside. You will also need to arrange away of locking the T-nut in position so things don’t shift when the tool post is released to rotate it. A couple of vertical grub screws running down through the nut jacking it gently up against the top of the Tee slot will work fine. Alternatively arrange a screw down locking collar on the tool post stud after the manner shown here :-

That is the stud and fabricated T-nut to fit a Dickson post on my P&W Model B lathe which uses the same style of T-slotted top slide as the Sable (and other SouthBend clones) only rather larger. The joint in the fabricated T-nut is just visible. The screw down locking collar sits nicely inside the recess in the base of the Dickson. Tightens with a pin spanner, one hole is visible. That lathe had been used for many years with a simple square plate to hold the tool post down severely distorting the area where the tool post sat. So much so that the post would no longer clamp properly securely in rotation. Took a lot of work to get things flat again, including significant building up with weld.

If funds are short consider making up several four or two way blocks similar to what you have and swopping tool loaded blocks. As you already have the remains of ratchet system it shouldn’t be too difficult to ensure things interchange and return to the same place.

Clive

[DiogenesParticipant @diogenes]

The main things you need to know to calculate the size / inform your choice of any toolpost are;

The distance from the top of the topslide to the spindle centre-line.

The dimensions of the ‘T’ nut – tho’ easy to make/modify one.

..and to a lesser extent, what size tools you need to hold.

The aftermarket ‘wedge types’ are also a reliable and solid system and usually come with a ‘T-nut’ fitting on the bottom of their post (check description/with supplier).

The holders are very cheap, widely available or easy to make, and the design is inherently forgiving of dimensional variations.

 

[Clive FosterParticipant @clivefoster55965]

Further comments concerning secure mounting.

It’s important that the post clamps down on a region close to the outer edges rather close to the centre. Obviously this gives more “leverage” against rotation when compared to holding close to the centre.

The tool post / holder mounting area of the top slide on older machines is rarely flat. Even if apparently undamaged the continually repeated stress of bolting the post / holder down tends to make the cast iron flow and rise up around the fixing. Whether the top of the T-slot or around the tapped hole provided for a mounting stud in plain topped slide. Ideally you should attend to this by machining or filing flat. If hand work is the only way and your skills aren’t up to getting it super flat a ring washer of thin aluminium does decent job of spreading the load.

The official Dickson toolpost design has a recess of diameter approaching half the width of the post to, among other reasons, shift the clamping loads away from the centre. A good idea but it does mean that a small T-nut will tend to distort the slide in the middle and not provide proper retention. Many of the affordable posts, whether wedge or Dickson clone come with rather short T-nuts. Often the centre recess is omitted too. Ive seen smaller machines, of similar size to your Sable, where the toolpost was only clamping on a ring bout 1/8″ directly wide around the post. Careful inspection showed that the apparently firmly seated post was a thou or three clear of the slide for virtually all its width. The owner complained of serious chatter. Obviously the post was rocking in the clearance under varying cutting loads. Not easy to see on the machine.

Mr Dickson uses a stepped post holding stud with a stepped space at the top to confine location forces to top and bottom. This is a more predicable layout than trying to use a snug, constant diameter stud. The top and bottom registration scheme handles any perpendicularity error between stud and slide better and ensuring well spaced, positive location at both ends where a snug, content diameter stud may only contact in the middle.

These little niceties are important to successfully coping with that gremlin infested job that is determined to chatter on you.

For me one of the nicer things about the Dickson is that they are trivially easy to disassemble to clean out any swarf that may have gotten inside. Swarf in the innards really won’t help the action of any QC tool post. I feel it’s important to have a regular maintenance routine of keeping the innards clean whatever breed you use. The innards of my Dicksons have an infuriatingly “magnetic” attraction for the really fine stuff.

And one more thing concerning use.

Whatever the breed of QC post hold the tool carrier as close to exactly in position as you can mange before locking things up. Relying on the lock to pull the carrier into place tends to give inconsistent, lower than ideal, locking forces and may damage or distort things preventing perfect operation in future. The Dickson is notorious for bending the stud carrying the height setting thimble under significantly abusive use. Maybe an annoying feature but very easily fixed and obvious evidence of encounters with gorriliod machinists in the past. Which can be important evidence when assessing a used lathe.

Clive

[Clive FosterParticipant @clivefoster55965]

Ooops. Erratum re above post

Third paragraph

for ” clamping on a ring bout 1/8″ directly wide around the post ” read “clamping on a ring about 1/8” wide immediately around the post.

Fourth paragraph, first sentence

“Mr Dickson uses a stepped post holding stud with a stepped space at the top to confine location forces to top and bottom.”

Should read

“Mr Dickson uses a stepped post holding stud with a stepped spacer at the top to confine location forces to top and bottom.”

Clive

[gerry45Participant @gerry45]

Thank you for the replies, lots of reading. Here are the photos of what i have. Looks like i just need a quick release tool holder that will go over the existing post. The post is 1 inch diameter.

Don’t need the rachet it was never there.

[Clive FosterParticipant @clivefoster55965]

Objectively the T-nut is still a little short. Looking at the scuff marks on the top-slide surface it’s evident that the tool post hasn’t been sitting quite as firmly at diameters greater than the length of the T-nut. Flatness error is almost certainly small enough to be hard to correct so a thin aluminium washer will take up the difference just fine.

With luck a Dickson clone will have recess big enough to go over your ratchet base.

However that is seriously good small four way.

In your position I’d save myself a small fortune by re-instating the ratchet and making a couple of copies by gluing and screwing together stock sections of plate and bar. Many years ago I made some for my SouthBend’s using steel plate top and bottom with a square section light alloy centre. Worked well and my (Twiggy skinny!) wallet was much happier for it. Made a very effective a poor boys QC system swopping pre-loaded blocks carrying 2, 3 or 4 tools as desired. Never got round to making a nice ratchet, like yours, which would have made it so much better. If you have your shims organised setting up by measurement off the machine is much easier than the “sort through random scraps then cut and try” on the machine process that many less experienced folk resort to. If you plan to use carbide inserts, whether mostly or all the time, the ready height adjustability of a QC is irrelevant anyway.

To exploit a QC you will need a good centre height gauge. I like the optical type. Basically a reasonably thick, 6 mm or more, piece of perspex arranged to stand vertically on a convenient part of the machine with a line scribed at centre height on both sides. Use a sharp centre in tail or headstock to get it right. Two lines on opposite sides of the transparent upright make it easy to avoid parallax error it you have to squint across from a distance. The lines merge into one when you are looking straight. Mine can also mount a small mirror at 45° so i can look down from above if need be.

Don’t skimp on QC holders. Common consensus is that at least 8 are desirable, plus a parting tool carrier, to give you a useful preloaded set to cope with most jobs. The whole point of a QC is that you change out pre-set tooling. Not merely a slightly easier way to set re-ground tooling back to centre height. I’ve got 16 or so holders to share between my two lathes. Both tool posts have been carefully shimmed so the tooling can swop from one to the other without adjustment.

Clive

[BazyleParticipant @bazyle]

The Sabel is a 4.5in lathe same as the Boxford. So you want the next size up from the ones sold for Myfords. You can use a (cheaper) Myford size but will need a thin spacer plate.
However it sounds like you are a bit new to the game so a QCTP is well down the list of things you need. They are a bit of a modern obsession and while nice to have they just are not the solution to any problems you are having.

That’s a very nice 4-way so you would be better off making a couple of extra blocks for it. “too difficult to make”? then you don’t have anything like enough experience to justify spending on a QCTP.

[Howard LewisParticipant @howardlewis46836]

If you stay with the four way post, (Almost as quick as a QCRT, and slightly more rigid) do replace the spring and pawl, for the ratchet.

This will ensure a consistent location for the four way post when you change positions, and a stop to resist cutting forces.

(Although there might well be occasions when the toolpost needs to be positioned other than against the stop; just make sure that it is always firmly clamped.

But +1 for a Centre Height Gauge, of some sort. Although not on piece work, setting a tool to centre height is quicker.  And easier, since you can see how much the height needs to adjusted with shims.

In forty years,  have thought about a QCTP, but never bought one.

WHY?

Together with holders, it would probably cost about m£300 at today’s prices, and involve modifications to fit.  (It would seem ironic to use a four way post to make the parts to fit a QCTP).

Very little space available to store all the spare tool holders

Having made, and fitted, a four way indexing rear toolpost, at least six tools can be available, (FRONT – Rougher, Finisher, Boring bar, REAR front chamfer, Rear chamfer, Parting tool)

IME, parting off with the tool inverted in a rear toolpost, causes far fewer problems – the swarf falls away rather than staying to clog the cut.

 

[Andrew CrowParticipant @andrewcrow91475]

Hi Gerry, I would fully agree with the two previous posts, there is nothing wrong with the four way tool post that you have. Just cut your packing  pieces a bit smaller than the ones shown so that you can use all four spaces.

I have one on my old Colchester Student and once  set up it’s much quicker to rotate the tool post than change the complete tool holder of the qctp that I have on the Myford.

Andy

[Bazyle]

On Bazyle Said:

The Sabel is a 4.5in lathe same as the Boxford. So you want the next size up from the ones sold for Myfords. You can use a (cheaper) Myford size but will need a thin spacer plate.
However it sounds like you are a bit new to the game so a QCTP is well down the list of things you need. They are a bit of a modern obsession and while nice to have they just are not the solution to any problems you are having.

That’s a very nice 4-way so you would be better off making a couple of extra blocks for it. “too difficult to make”? then you don’t have anything like enough experience to justify spending on a QCTP.

Bazel has a very good point, QCTP are not all they are cracked up to be, especially if you intend to purely use carbide (noting your tool bar.)

Great for HSS which constantly changes height as you sharpen it and way too floppy for parting on the older worn machine with such a small size of block. I now hardly use my Myford size QCTP and carbide goes through a lantern style with a custom ring spacer for each type of tool holder.

[DiogenesParticipant @diogenes]

The wedge type toolpost (size 111) I bought from Arc currently costs about £90, with three holders – the next size up (#222), is about £100 with three holders – the 111 holders individually cost £15, size 222 are £15.50 each.

For me it’s a no-brainer – I find I swap tools quite frequently (RH, LH, Facing, Chamfer, Metric thread, Imp thread, long-narrow tip, parting / grooving tools (at least 4 or 5 in HSS and carbide, why use a long overhang when a short one will do, why make a wide cut on a tiny component when a narrow one will do, boring tools (a very large number  of options; same philosophy – why continue a 12mm hole with an 8mm tool when you can swap out for the fatter bar in seconds?).

It’s very liberating, much more efficient, and (personally) much reduces the temptation to continue with sub-optimal tooling for the work immediately in hand.

[gerry45Participant @gerry45]

Having read your replies and had a bit of a think about it at the end of the day i am not really going to make anything with real precision. And as some of you say the existing tool holder is pretty good. I can get probably 2 tools in it if i really need to and there could be a lot of faffing around and expense just to save very little time. So i will find some more shimming and make to the right size and keep what i have.

Thanks for your input.

All i need to get to add to my tools is a parting off tool. What would be the best for me and this lathe?

[bernard towersParticipant @bernardtowers37738]

As your lathe does not have a T slotted srosslide your parting off would have to be from the front so using a blade of less than 2mm would be an advantage. Chronos used to sell a blade with a T shaped top that seemed to work well. I find the thing with parting off you have to grow a pair and be brave and once you’ve done that it gets easier over time IMHO

[Howard LewisParticipant @howardlewis46836]

Presumably, the chuck is screw on?

Unless there is some means of preventing it from unscrewing, do NOT mount the parting tool inverted in the front post and run in reverse!

FWIW

Keep the parting tool well lubricated, and maintain a steady slow feed, but don’t force it!

My preference is for zero top rake, to reduce the risk of dig ins.

Howard

[PeteParticipant @pete41194]

It’s only my opinion, and likely many here won’t agree. But I’m using what G.H. Thomas detailed for his thoughts about lantern type tool holders, 4 way tool posts and what were then available for smaller lathes and qctp’s in this book. https://www.teepublishing.co.uk/books/in-your-workshop/model-engineers-workshop-manual/ And I’m also using my own results, measurements and what I think are logical conclusions.

I’d guess that GHT was more than able to afford anything he really wanted for additional tooling, and likely much better than most of us here could. Yet as far as I know, he never used a qctp on his own lathes in his home shop. He even designed and built his own ratcheting 4 way tool post to gain enough repeatability during any multiple part productions on his own Myford Super 7 lathes. Nor does it seem qctp’s were used on the much larger lathes for his business since he mentioned how good and repeatable he thought the British made Herbert brand of ratcheting tool posts were on those far heavier and more industrial sized lathes.

While I own and will sometimes still use my own off shore example of a qctp, and I did buy enough tool holders. The OEM 4 way tool posts my lathes came with are still much more rigid than any qctp. Less than 20 minutes, an indicator and magnetic base can easily prove that. And for all of the exact same reasons GHT detailed. In hindsight and what I now understand a lot better, I’m not all that sure I’d spend the same again on any qctp and the number of tool holders I bought. When or if metal removal rates, accuracy and surface finish are important enough, my 4 way tool posts will still do better than my qctp. Slightly quicker tool changes are about all there really better at. For larger parts, bulk metal removal and the available horse power, my 4 way TP will still remove material quicker, and I think more accurately and better than my qctp. If I could have only one single method of lathe tool holding? It would still be a 4 way TP.

 

 

[gerry45]

On gerry45 Said:

…All i need to get to add to my tools is a parting off tool. What would be the best for me and this lathe?

Parting off being the most difficult of the basic lathe operations is a subject in itself.  The cutter is broad and needs plenty of power to drive it. The lathe has to be as rigid as possible, so small lathes are a problem.  Big lathes cope better, but not if they’re worn or out of adjustment.   (Condition matters: where is your Sabel on the “as new” to “beaten to death” spectrum?)   A steady hand is needed, or – much better – a powered cross-slide.   Vital to clear swarf and lubricate, especially so with deep cuts.   Front tool-posts being bendy make parting off from the rear popular.  A “Gibraltar Toolpost” fitted at the rear of the slide is more solid, and it grounds cutting forces more effectively, making it less likely the saddle will lift and twist.

I use three different types, all sold by ArcEuro, from whom I’ve stolen the pictures, other suppliers available:

1.  An  8mm HSS blade. Used mostly on small diameter Brass, though it does steel too.  Not so good at deep cuts.  The example pictured shows a blade with relief, which is awkward to resharpen, and doing so alters the tool height.  I use an easily resharpened flat blade, no relief, that probably doesn’t cut quite as well.   HSS requires a grinder and grinding skills; not everyone is good at it!

2.  A carbide insert holder.   No need to sharpen, and the tool-height isn’t altered by replacing the insert, but carbide prefers to be run faster and harder than HSS, and older lathes may not be up to it.  (Fast cutting with carbide inserts was science fiction when the Sabel was designed.)   That said, carbide mostly works “well enough” at slower speeds, and it would be good for grooving large diameters on a slow lathe.   I mostly use mine for grooving and parting small diameter steel and harder metals, but not as much as expected – see entry No. 3!

 

3. Is a blade type holder, the advantage being they are stiff enough to take deep cuts, the one pictured parting off up to about 70mm diameter.  I use mine a lot, almost everything apart from fine work in Brass or Aluminium.   It’s rear-mounted in a Gibraltar tool post and the lathe runs in reverse at 2500rpm .   Don’t do this with a simple screw-on chuck, because they come undone!  But reverse is fine with bolt on and cam-lock chucks.   If the lathe can’t do reverse safely, the tool can be mounted upside down and the lathe spun normally – still better than a front tool-post.

Next question is who to buy the blades and holders from!

• Second-hand ex-industrial from ebay and friends.  This is a risk, ex-industrial is often well made, but that counts for nothing if the tool is in poor condition.  Don’t expect any support.
• Too cheap from ebay and online friends.   A different risk!  Enthusiastic bargain chasing often ends in tears.  “Too cheap” refers to the build quality, not the asking price.  “Reassuringly expensive” is a well-known con –  buyers believe a high-price means the item must be good.  No “must” about it – fakes, factory seconds, paying for the brand and advertising, etc etc.   Hard to tell the difference between good and bad, so always a gamble.   Often possible to get money back though: read the Terms and Conditions.  Don’t expect any support.
• New industrial.  Low risk, but expensive!  Many newcomers arrive in the hobby determined to buy only the best, until they see the prices!  Well supported, not necessarily free.
• New mid-range from a reputable supplier.   These days many tools are manufactured for the middle-of-the-road market.  Not as robust as industrial tooling, but certainly not “too cheap” either.   I prefer to buy these from established UK vendors, many of whom advertise of this site, selling into the hobby market.  If by chance they sell you a lemon, they stand by the product – replace or refund.  Support varies: ArcEuro have a good reputation, and Warco sorted me out with no fuss.
• Mid-range is a good choice for moderate hobby use, not so much for hard work.   So, are you a genteel hobby metal worker like me who doesn’t stress his tools much, or must you cut lots of metal quickly, day after day like a Victorian piece-rate worker?    If the latter, or you find tools don’t last, go up-market, otherwise save lots of dosh by buying mid-range!   The cash may be needed to buy metal and it’s expensive!!!

No-one provides beginner tutorials by phone.  Look to the web for that, including here!

Dave

 

 

 

 

 

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