Lathes & M/C tools

[bertiedog]

If the advice is checked, I advised exactly what you intend, a system that does not use the screw, which some commercial additions to lathes use.

 

Adding a modified vernier (or a commercial DRO), gives a reading of the slide, not the screw. Pro DRO is designed to be read by the computer and the derived digital control signal used to maintain the position of the slide.

 

But in this case if the drive is via the screw backlash does enter the positioning of multiple cuts, retracting the tool for the next cut will give a figure, but the screw has to advance to the new position to take up backlash to ensure the tool cuts at the right figure, in other words the DRO is showing exactly where the tip is, but the screw may not be putting thrust against it at that position, so that contact with the work causes the tool to move. Of course with CNC it will be detected and corrected, but not with a manual system.

 

The main offender is the DRO on the Seig and other small lathes, which read the slide using the screw, backlash can give troubles here. Experienced users will have no problems, backlash can always be allowed for, but a new comer may take the DRO at face value and use it ti make say multiple step diameters, taking the DRO indication as accurate, when it will not be. A series of descending diameters would work, but not ascending values as the tool backs off.

[polybear]

Hi,

Owners of Taig Lathes (also known as Peatol in the UK) often fit DRO's in the manner you describe, i.e. actually measuring position of the slides. Often they source cheap digital verniers (Lidl and Aldi regularly sell them for about £8 a time, and the readings stack up exactly with my Mitutoyo Micrometers), then cut off the caliper jaws (sounds brutal I know) and mount them using suitable adaptors/clamps etc. Here's a couple of websites showing the general idea, all taken from the Cartertools website:

 

http://www.cartertools.com/picture.html

 

http://www.emachineshop.com/machine-shop/Taig-Lathe/page123.html

 

http://www.mechanicalphilosopher.com/llell01.jpg

 

On the Taig lathe (I have one, with 3 Lidl DRO's waiting to be fitted sometime...) it's not unknown for people to fit them to the saddle position, crosslide position and tailstock ram).

 

HTH

Brian

[ozzyo]

There are a few suppliers of all the bits you need - such as Machine-DRO

 

http://www.machine-d...s&category_id=3

 

Jim.

 

 

 

Thanks for that link, flubrush / Jim,

 

I've now order one from them. at a six inch. length. The cross slide travel is about 4 1/2" better to much than to little ( next size down was 4 inch.).

 

 

These are photos of the back of the cross slide, now all I now have to do is try and fit it to the cross slide.

 

OzzyO.

[ozzyo]

Hello all,

 

My DRO turned this morning in the post, not bad 2 days from ordering to delivery.

Now all I have to do is figured out how I'm going to mount it.

I will try and keep yous posted on this as I go along.

 

OzzyO.

[ozzyo]

Hello All,

 

been doing a bit more measuring and planing just need to get some metal for fixing the DRO to the M/C. I may have got away with the 4" DRO as the 6" has about 3/4" overrun, but hey you don't know that when you buy them, and it was only a couple of quid more (IIRC £3).

 

I think that I've got the main mounting bracket drawn up as I need it, so its going to be measure once and cut three or four times, sorry that's measure three or four times and cut once.

 

The only thing that gets me is the mounting screws for the read out stick out more than the mounting brackets lift the rule / reader rail (strange)?

 

OzzyO.

[ozzyo]

Hello All,

 

well after more planing and drilling. I'm at the stage (shouts of get on it its leaving) where I can start to mount it to the lathe. The only part that I'm undecided about is the main mounting, this has a rebate M/Cd in its top surface to clear the mounting screws. Do I M/C it into a slot (swarf will drop through) or leave it as a rebate.

 

I think that the mill is calling me.

 

OzzyO.

[ozzyo]

Hello All,

 

well I've got the DRO mounted onto the lathe, it has not been all clear sailing but it has worked. So onto the build?

 

The main mounting bracket with the mounting and clearance holes drilled in it, the slot for clearance for the mounting screws milled in as well (more on that later).

 

A test fit of the DRO unit, this showed that the clearance slot was not wide enought.

 

So a wider and deeper slot was M/C in it.

 

Well I still wasn't happy with it it didn't look right, so back on the mill and milled right through it, this will let most of the swarf drop though it. I hope?

 

The mounting bracket for the DRO reader mounted to the cross slide. I was going to make this about 2" long, but then thought if I leave it about 10" long it should help keep swarf off the reader. Only time will tell.

 

All mounted up, just some small jobs to do. Now all I have to do is to get used to using it and not the dial. All the parts were setup to within .001" over the full travel of the cross slide. Now for some test work (you watch me drop something on it and bu99er it all up).

 

OzzyO.

[ozzyo]

Hello All,

 

I've now done some test work using the DRO, it seems to work nicely, the hardest bit is getting used to using it and not the dial on the lead screw but that'll come with use I hope.

One thing that I have found is when you turn it off and back on it resets back to zero so if you have several setting you need to leave the cross slide at the zero position.

 

OzzyO.

[richard_t]

Well I've finally got my lathe and mill up on their respective stands, and pretty well leveled in the case of the mill, and not twisted in the case of the lathe (it's not level!). I hope a couple of pictures are OK:

 

The lathe - Warco WM-250:

 

The mill - SEIG X3 (small!) mill:

 

First job will be to turn a rod to store the change gears on.

[PhilEakins]

Gosh, don't time fly - I could have sworn that the last post was a couple of days ago ....

 

Anyway, after about 30 years I finally have a place to set up my Unimat SL 1000 (sold in the UK by Elliot) as a drilling/milling machine, and my newer Unimat SL Basic as a lathe, permanently. Having to continually clear them away was always a disincentive to their use.

 

The SL 1000 is now very old (but a valuable machine going on what they fetch on e-bay) and accessories are hard to come by and are expensive.

 

I've sourced a 12mm X 1mm pitch (the SL 1000 standard) to 14mm X 1mm pitch mandrel so that I can attach more up-to-date Emco 14 X 1 fittings enabling me to use a range of collet chucks for the newer Emco machines. However, the mandrel is in itself a collet chuck for ER11 standard collets (not bad for forty quid!).

 

Now, my question is - ER11 collets are 18mm long whereas ER16 (other Emco/Unimat collet chucks on offer) are 27mm long and I think might offer more support to the tools. So should I buy an extra collet chuck for ER16 or will ER11 suffice? I'm not anticipating any very heavy milling, at the moment that is.

 

Any advice gratefully welcome as you will obviously see, I'm a tyro at this.

 

Phil

[bertiedog]

Best stick to the size the chuck is meant for, I am not sure the back end would be correctly supported with the longer collects, as the mandrill might foul the back end. All ER collets are designed to hold at the tip end, which is the reason for the range, they must be a close fit before closure.

 

There is a thing to bear in mind, the capacity of the cutter is limited on the SL to about 5mm, no bigger, and generally it is best to use smaller cutters, and this even applies to soft brass, let alone steel..

 

You can still track over large areas, and cut wider slots with multiple passes, and I find the best tools overall for small model railway work are carbide burrs and end mills with a 1/8th shank, that fit the drill chuck, or a home made single size dead holder, which has a drawbar to retain it, with a screw bolt to retain the cutter in a reamed hole.at the working end.

 

The SL can swing a face cutter of large diameter, at low speed and very light cuts, especially useful on aluminium.

 

Stephen.

[PhilEakins]

Thanks Stephen, now I've paid for the thing and I'll see what arrives.

 

I wasn't thinking about forcing a different size collet into the chuck for which it was not designed, but the 'nose' of the fitting is threaded so that I can add later issue (14 X 1) chucks. For example, I can mount a 'Unimat 3' four jaw chuck on the SL - not that I want to, but I could.

 

As I said, I'll see what comes and ask again if I need to.

 

or a home made single size dead holder, which has a drawbar to retain it, with a screw bolt to retain the cutter in a reamed hole.at the working end.

 

Ummmm, that would act a bit like a correctly sized collet then?

 

Phil

[bertiedog]

[quote name='PhilEakins' timestamp='1305920896' post='400468'

Ummmm, that would act a bit like a correctly sized collet then?

 

Phil

A dead holder is just a a drilled and reamed hole in a steel bar, made to fit the mandrill of the lathe, the holder hole matching the cutter as closely as practical, with a simple screw through the side to hold the cutter. A well made dead holder is as accurate as a milling chuck, and a lot more compact.

 

As the Unimat has no taper in the lathe mandrill the holder back should be a good fit in the mandrill hole and as deep as practical, with a 6mm threaded rod screwed in to the back of the holder, and a nut on the outer end to secure it in place.

 

Make the fit of the holder stub a very, very slight taper, in other words the tip should go in easily and as the holder goes in it tightens a bit. Just turn parallel and then emery the stub till it fits and take off a little more at the end.to ease it into the mandrill accurately.

 

If you use a lot of carbide 1/8th shank burrs and cutters, then you can glue the cutter bit in!! When they wear or break, then heat to boiling point of water and pull out the remains and glue another in with superglue. Don't not throw away the shank, simply regrind with a diamond disk in a Dremel drill, and it makes a single point face cutter etc. or can be used as a lathe bit in a small holder.

Stephen.

[PhilEakins]

Thanks again Stephen - I see what you mean.

 

One idea which occurs to me, is that instead of securing the fitting from the back end, is to bore, thread and then turn an extension to the spindle which can then be bored/reamed/tapered to take a tool (secured by set screw or glued as you say) which would then be perfectly concentric to, and balanced with, the head end each time it's fitted for use.

 

I've found a couple of sources for compatible taps and dies for the spindle head (which opens up even more tooling possibilities of course!).

 

As I said - although I've had the equipment for some (long) time I'm really a just beginner exploring what I can do and what's best practice.

 

Phil

 

PS I didn't take metalwork at school, which was an awfully long time ago!

[bertiedog]

You can screw an adapter on to the lathe mandrill thread, but it is not good practice with milling, nothing to do with accuracy, but the blows and torque from the cutter continually tighten the threads, and will make it difficult to remove. I know the Unimat is small, but it could also risk damage and extra wear to the thread. As mentioned before the drilling chuck can take small cuuters as long as done up tight, and checked every so often to see it remains tight. Vibration may loosen the cutter, and the size should be no more than 5 mm or so, preferably smaller.

 

In general milling machines have a drawbar attached adaptor or chuck in the mandrill for safety reasons , and quick changing of the tooling, without risking locking the tool on a thread.

 

The Clarkson chuck, far too big for the Unimat, uses the thread on the back of the milling cutters to lock them automatically from the forces of the cutting, but the chuck itself would be on a drawbar to hold it to the mandrill of a lathe or milling machine.

 

There is no need to have more than one dead holder, make it take say 10mm tools, and simply sleeve all the smaller cutters with a steel sleeve of 10mm diameter. Each tool is glued into the tight hole with Superglue or Loctite.

 

This provides a system for accurate holding in just one holder, the locking screw bears on the sleeve in this case to retain the cutter and sleeve.

 

Stephen.

[ozzyo]

 

In general milling machines have a drawbar attached adaptor or chuck in the mandrill for safety reasons , and quick changing of the tooling, without risking locking the tool on a thread.

 

The Clarkson chuck, far too big for the Unimat, uses the thread on the back of the milling cutters to lock them automatically from the forces of the cutting, but the chuck itself would be on a drawbar to hold it to the mandrill of a lathe or milling machine.

 

There is no need to have more than one dead holder, make it take say 10mm tools, and simply sleeve all the smaller cutters with a steel sleeve of 10mm diameter. Each tool is glued into the tight hole with Superglue or Loctite.

 

This provides a system for accurate holding in just one holder, the locking screw bears on the sleeve in this case to retain the cutter and sleeve.

 

Stephen.

 

 

 

This may work as long as you are pulling the adapter up in to a taper on the milling head, to use "glue" to hold a milling cutter don't be daft..

The use of a screw to hold the cutter is well known , but it can cause the cutter to run off.

The Clarkson Chuck was one of the best ones that I used when I was in engineering as it used the large screw on the body to hold the collet in place then any cutting force on the cutter would tighten the collat on to the shank of the milling tool.

 

If you have worked in engineering you will know the Dead lock chuck as well. now tell me how that works?

 

OzzyO.

[bertiedog]

Well maybe being a qualified mechanical engineer helps a bit, but the advice was given in relation to a small Unimat with very small cutters plain shank cutters, where gluing shanks of a larger size on to the small cutters is a acceptable workshop practice, using Loctite, who issue instructions for such uses.

 

As long as the clearance is tight in the reamed hole and the tool just fits, the loctite floats the cutter and the accuracy is very good, usually within .25 thou, or tighter, on the cutter bit shank, to the collar shank.

 

The practice of gluing with Loctite, (or superglue) comes from the maker of very fine quality chucks, milling machines and Lathes, Schaublin, the Swiss manufacturer, and is common workshop practice for small drills, cutters, burrs, cutting disk holders, with shanks below about 4/5 mm. David Kane products issued advice on glue retention in 1969, using various grades of superglue.

 

I have never had a milling cutter come free from a collar, except in one case of over heating a carbide burr, the heat softened the glue. This was using an air motor to drive at 30,000 rpm, no way would a Unimat be able to over heat the bit in the same way.

 

A mention of using glue to retain tapers was made, this is indeed done, but is extremely bad general practice, unless a draw bar is used as back up. If the taper has no " natural sticktion" as it closes to tight, it is, in impolite terms, "knackered", and needs a total re-grind and lapping to restore the fit.

 

I am very fully aware of the Clarkson Autolock milling chuck, the designer was a close family friend of my father's, and I use a couple in my own workshop, one is entirely home produced to slim down the design to fit smaller milling machines, mine fits a Hobbymat miller. The larger mill I have takes the normal small series Clarkson, up to an inch capacity.

 

 

The Clarkson dead lock chuck version simply uses the same screw on the back of the cutter, to retain the cutter in the milling chuck, with a removable three jaw collet, from a set of preferred workshop sizes, then it is closed by the internally tapered screw on nose being done up tight with a ring spanner. The closure of the jaws sets the cutter concentric to the spur, usually within a tenth of a thou, or better to the shank.

 

 

This design is commonly used in Far Eastern versions of the milling chucks now sold for Model Engineers. it is quite accurate, and safe, as the back thread is tightened by the forces in a simular way as the Clarkson Autolock. being far smaller, it fits the average sized home machinist milling machines. It is still to big to fit the Uninmat milling set-ups.

 

All dead lock chucks, and Auto lock, should be used with draw bars through the lathe or milling machine mandrill for safety, it could come loose at speed and is a potential disaster.

 

The Clarkson Autolock is a superior design as it uses non-matching thread pitches to cause a lock as the tools is inserted, the cutting forces accurately forcing the threaded cutter on to the "centre spur", which means the cutter can be moved, and replaced, at exactly the same depth, something the dead lock version cannot guarantee.

 

With the Autolock the retaining collar nose is only hand tightened with a special small ring spanner, and the work forces lock it, requiring only a relatively light force to be applied with the special ring spanner to loosen the nose. An ordinary larger spanner should not be used, it risks over tightening the Autolock, which can damage the vital back spur in the base of the chuck, loosing the accuracy built in.

 

The Clarkson Autolock come with sets of precision collet jaws, from three to multi-jawed versions, which close over a very narrow range of preferred sizes for greater accuracy.

 

Now being more practical for the home machinist, they do not need these large chucks for smaller machines, the Dead Lock will do for most sizes encountered in the home workshop.

 

However the Home Machinist will not have a full set of screwed back cutters, they usually have a junk assortment of every conceivable shank type!, this is why plainer chucks will work better.

 

Also most machines can take morse taper dead holders, which hold the cutter by a grub screw.

 

These are accurate enough for normal work at home, the off set induced by the screw moving the tool sideways in the hole can be forgotten for facing work anyway, and will not affect the side cutting to any degree that a home machinist will notice.

 

Milling cutters are not that well finished anyway, stock cheaper ones are not true on test rigs, we used to test them at work, and in any cutter ground on tips is going to be at least a few microns different. For precision single cut CNC set-ups, yes, we ground the cutter in situ to guarantee concentricity, but it was usually easier to do two pass cutting in a channel.

 

I do know a bit about tool accuracy as we made scientific optical equipment, and BS standard Test gear,( YES, we made the test items for BS standards!).

 

But this is worlds away from a Unimat, capable of the same standard work in the right hands, but who would use those standards for Model Railways?

 

My posted advice is for the Home Machinist, who has limited time and cash, usually simple equipment, in a garage or kitchen, not in a fully equipped workshop.

 

My own has 5 lathes and two milling machines, plus surface and specialist tool cutter grinding, far beyond the requirements of model railways, as I do watch and clock work, and restore motor bikes and model engineering in 3.5" and 5" live steam, and stationary steam engines.

 

I fit common shanks to all my smaller drills as well, this means a number 80 can be placed in a three jaw drill chuck without a pin chuck. It also only exposes the working tip , plus a 1/4 inch, prevents breakage etc, for longer and deeper holes I use an ordinary drill in a pin chuck to follow through to the required depth.

 

All the smaller milling cutters are treated the same, carbide, steel and dental burrs, diamond burrs, and multi toothed Swiss milling cutters. Some are left un-modified to still fit Dremel Tools chucks, all are secured with Loctite or Superglue. Super glue is just as strong, but is awkward to use as it sets so fast, loctite gives time for adjustment. There are special slow set Super glues, but why bother when Loctite is designed for the job?

 

Stephen.

[PhilEakins]

Cheers Stephen - you've got me convinced. You're quite right, I hadn't thought about over-tightening in use, even though I had some shaper tools for wood used in a power drill which did just that!

 

However the Home Machinist will not have a full set of screwed back cutters, they usually have a junk assortment of every conceivable shank type!

 

Have you been looking in my tool draw?

 

Phil

[ozzyo]

 

The Clarkson dead lock chuck version simply uses the same screw on the back of the cutter, to retain the cutter in the milling chuck, with a removable three jaw collet, from a set of preferred workshop sizes, then it is closed by the internally tapered screw on nose being done up tight with a ring spanner. The closure of the jaws sets the cutter concentric to the spur, usually within a tenth of a thou, or better to the shank.

 

Stephen.

 

Hello Stephen / All,

 

a very good reply, but I must question you about the above quote. That sounds like you are describing the Clarkson Autolock chuck.

 

The Clarkson Deadlock chuck that I used had a collar about 1 1/4" in dia. with a multi start thread in the body that was locked in the closed position by the use of an Allan type of screw (it wasn't an Allan screw but that's how best to describe it). The cutter was screwed on to an extension of the multi start thread using a thread of about 1" dia (internal on the cutter external on the extension). The cutter would tighten its self up as you cut.

 

To release the cutter, you would unscrew the R/H Allan type of screw and then tighten the L/H Allen type of screw. The first screw would unlock the multi start internal screw and the second one would start the multi start thread to move.

 

We always stored these chucks ready to use. One time that I know about a new miller did not check the chuck was ready for use and mounted a cutter on one the cutter was about 2" or 3" Dia. it took about an hour using brass drifts (used against the back of the cutter flutes) and large hammers to free the cutter. So my mate and myself took one apart, it turned out that if you take the R/H screw right out there is enough movement on the L/H screw to unstuck the cutter.

 

Sorry I don't have a photo of one but if you go on EBay and type in Clarkson Deadlock you will see some.

 

OzzyO.

 

PS. the second chuck that you have shown is normally for ER type collets. Not a dead lock chuck. This type of chuck works by friction only.

[bertiedog]

The second shot is a dead lock type, it secures via the screwed on collar, which contains not a work gripping collet, but one designed for milling tools with a Clarkson compatible back thread. The outer appearance is the same as a collet chuck.

 

Tools are never gripped in work collets, except in home workshops , and with some risk to safety, as they can loosen in operation.

 

Two or more dead versions exist, one with the spur, same as Autolock, and lots without the spur, but using the back screw.

 

Those with the spur are likely to risk over tighten, and damage to the spur, the reason the autolock exists, to provide consistent mounting every time within risk to the settings.

 

Clarkson, and most other makers do other tool chuck , the dual action screw retaining type you describe is not a dead lock as such, despite the term being used by Clarkson, as it offers a repeat setting like the auto lock is designed to do.

 

Tools getting stuck in any Clarkson indicates very vigorous use of the spanner or retaining screws or the work forces are very excessive, neither of which should worry a home machinist user. I used a 10 ton CVA , which could take five inch cutter, these fitted an autolock, and if any body slammed the tools into the work then all hell broke loose, also the chuck should never have been closed with normal spanners. The damage was to the tool back spur though, never a jammed closure collet, as this is what the autolock, and the simpler dead locks are meant to do, rarely jam solid.

 

The worse thing was to split the Clarkson screw at the back, and be unable to extract the tool for the collet jaws, the collar would come free, but leave the tool in the collet, which would require grinding to release.

 

The Dead locks tool chucks you describe have a multi start thread, which indicates they are meant to stop a jammed on collar bet this means, the retention relying on the back thread and the collet.

 

All of this is way beyond any home machinists equipment, I have several other tool collets, Zeiss, Lorch and Schaublin, all have versions of the Screwed in tool with collet principle, the Zeiss using an Autolock type with a multi start threed to coles, and a locking lever ever to release, al designed for Factory floor quick change without loss of settings.

 

The original query is, let us repeat, about a Unimat, using tiny cutters, slot drills and burrs, none of which fiit an Autolock, or any equivalent type, and simply need a dead holder or drill chuck to hold them.

 

Stephen.

[bertiedog]

And please let us not wander off into retaining plain shank cutters, recessed flats cutters, cam lock, breech threads, buttress thread retention, ball end retention, claw retention, and other methods used by Brown and Sharp, and other makes over the years!!! None are really suitable for smaller home mills anyway, bar retaining cutters with flats by cams or screws bearing on flats on the tool shank..

 

Stephen.

[ozzyo]

 

The Dead locks tool chucks you describe have a multi start thread, which indicates they are meant to stop a jammed on collar bet this means, the retention relying on the back thread and the collet.

 

 

Stephen.

 

 

Hello Stephen,

 

please re read my post, the cutter does not have a multi start thread, and the Deadlock chuck does NOT have a collet.

 

OzzyO.

[bertiedog]

it's seems the type you describe is a plain Dead Holder, called Dedlock by Osbourn Clarkson. I would have called them a dead holder, and the size, although compact, is far to large for a Unimat or any smaller mill, like Taig etc. It is not a type I used,at work having been used tor more advanced types with full locking., but a Brown and Sharp had similar plain holders, which required a flat ground on the stem to act with the screw that locks the cutter. They took plain, flats or screw in, with the screw in un-used as the B& pre dated he Standard Clarkson screw.

For home use a plain holder is perfect;y serviceable, especially if flats are added to the side of the cutter, even a Clarkson type screwed shank, to allow the screw to bear on a flat surface for extra grip.

The best grip in a plain holder is a hardened cam rotated against the flat, with a locking screw on the cam shaft. B&S and Zeiss did this system, along with Boley, Lorch and Schaublin.

All these collets are far oiutside home uses, where the problem is sizes and non standard cutters, where plain screw dead holders score all round, cheap, easy to make yourself, and flexible enough to take most cutter types.

[bertiedog]

Also the tools mentioned , as I wrote, do not have multi start threads, the collet closing cap has the multi start thread for quick closure, as with Schuablin and Ziess, the cap being tighten by rotational work forces only, just like the Clarkson, but with out the differential threads.

There is little point going over an area time after time on minor points of little importance to the problem we are assisting on, fitting small mills with assorted cutters for the home machinist.

Stephen.

[ozzyo]

I used a 10 ton CVA , which could take five inch cutter, these fitted an autolock, and if any body slammed the tools into the work then all hell broke loose, also the chuck should never have been closed with normal spanners.

Stephen.

 

Hello Bertiedog /All,

 

I used a 7 ton Parkson mill that would happily take 3/4" cuts at 12" per min using a 9" cutter. or when set up by myself cut a 1/16" keyway to .0005" tolerance in both dept and width.

 

What is this 10ton CVA ,please explain?

 

OzzyO.

 

PS.as a aside, I remember a mate of mine that was on a 25 ton (load on table) Kendall & Gent planeo mill and was cutting a key-way about 2 1/2" wide and had forgotten to take out the back lash on the lead screw. The next thing was BANG and bits of cutter were flying all over the shop.