Member postings for mgnbuk

I've always wondered why the Myford fans say a concave surface when facing is desirable bit not on a milled surface

Why single out "Myford fans" Jason ?

Surely it is normal accepted practice for all lathes (irrespective of maker) to face on the silgtly concave side of dead flat ?

Nigel B.

Ejected tool or workpiece is not CNC machine specific. Are you saying all lathes should be fully enclosed?

Perhaps re-read the specific example I quoted in my original post WRT issues that would require addressing to put a UK manufactured small ELS or CNC equpped lathe on the market.

When I was involved in such things, the company sub-contracted guard manufacture to guarding specialists for the design of guards - mainly on larger vertical borers. Containmnet of ejected parts was a consideration - it didn't matter if the guard was not fit to use after such a containment. Cincinatti quoted the design criteria for the containment capabilities of their guards in the manuals for the Sabre range of VMCs dating form the mid-80s.

This discussion is largely irrelevant to the original thrust of my initial post, which was intended as a "reality check" fo those suggesting that "all" current Myford need to do to enjoy widespread sales amongst UK hobbyists is to re-design the S7 to use a VFD and ELS / basic CNC to be able to sell a "better" UK made machine cheaper than the current basic S7. It isn't going to happen !

Nigel B.

I don't think it is fair to compare Cowells to Myford or hobby lahes generally.

The price comparison was to highlight the cost of producing a manual lathe in the UK, Robert, not a reflection on the build quality or capabilities of the Cowells machine.Their current price list shows a 90ME lathe costs £4128 inc Vat, which isn't to far off the costs of a new basic S7 from Myfords. What ever way you look at it, that is a lot of money for a small lathe, however capable it may be, yet I doubt that Cowells are getting rich selling tham at that price. It would be interesting to find out how many new machines current Myfords & Cowells produce per year - I doubt that the market for either is large.

As you say, providing adequate guarding is a minefield. I doubt that a safety line in front of a lathe would be adequate - not going to absorb the energy of an ejected workpiece or broken tool & safely contain the ejected object.

Nigel B.

That would then allow the DRO to operate from the encoders on the servos (an idea I'm not mad about, but would save a lot of cost, separate linear encoders would be an easy add-on though)

Motor mounted encoders are the usual arrangement on most CNC lathes I have come across - all of the 7 CNC lathes at my last employment (ranging from 200 dia. x 500 BC to 700 dia.x 3500.BC) were motor encoder position feedback. Scales are rare on lathes - in 27 years working for a CNC rebuild / retrofit company before my last employment I can only recall a couple of vertical borer installations where the customer requested scales. Occasionally some machines used separately mounted encoders driven directly off the ballscrews (rather than measuring through timing belt reductions) but, in practice, motor mounted encoders work just fine. One advantage of encoders is the ability to use backlash compensation, which isn't available with scales (you can only compensate for the lost motion within the readhead mounting arrangement on the scale) which can give better contouring performance. If extreme accuracy is paramount with an encoder arrangement, most controls made over at least the last 25 years have non-linear axis compensation (pitch error comp) to "map out" ballscrew errors.

Question :

How do you make a small fortune manufacturing manual machine tools in the UK ?

Answer :

Start with a very large one !

Best I can make out at the moment there are only 2 manufacturers of small manual lathes remaining in the UK - Myford (Mytholmroyd) and Cowells (Essex). If you thought that the asking price for a current new Myford S7 was high, have a look at Cowells price list ! That all the others have either stopped making such machines, gone to the wall or sub-contracted manufacture to the Far East says it all, really. The cost of setting up to make such machines here, labour costs (if you could find a sufficiently skilled workforce) cost of raw materials (if you could find a UK foundry capable of making the required castings), plus product certification costs etc.mean it is not realistically possible to come up with a UK made product that could be priced within sight of imported machines.

Talk of going with ELS or CNC systems means going for at least partial (ELS) of full (CNC) interlocked guarding - yet more cost. Harrisons went this route with their Alpha range of machines based on the M series manual lathes. They "got away" with partial guarding on their basic ELS equivalent machines because they were not capable of automatic cycle operatation, but later - more capable - machines that could run programs had to be fully guarded. And they are not made here any more - UK manufacture ceased at least 10 years ago (probably a lot more - time flies ! ) in favour of making them in the Far East.

Integrated spindle motors for lathes are a thing from several manufacturers - they are sold in component form comprising a sleeve with permanent magnets attached to press over the spindle, a stator cartridge with windings fitted into a laminated core that presses into the headstock casting & an encoder to fit the spindle on the outside of the rear bearing cap for commutation and positional feedback to the drive & control system. They can be forced air or liquid cooled. You don't want to ask the price !

The UK machine tool industry is largely gone & is, I feel, unlikely to come back any time soon - if ever. The skills base has gone, the cost of rebuilding the industry is just too high & the returns are unlikly to keep the current crop of "instant gratification" investors happy. If Communist China gets to be too expensive as a mnaufaucturing base, then India is probably the next most likely candidate to take over at the lower price end of the market.

Nigel B.

If you have (or have access to) a 3D printer, there are a couple of morse taper cleaners on Thingiverse - I have made one of these and it works OK. Glueing on thin strips of fine (grey 600 grit) Scotchebrite should get rust off gently.

Nigel B.

I have a Chester Conquest 7 x 13" mini lathe that has the "hardened bed" sticker on the end of the bed, I also have a set of Tsubosan hardenss testing files - 6 files of varying hardness that are used to test surfaces for hardness between HRC40 and HRC65. If the file is softer than the surface, it doesn't "bite" and skates off without marking the surface. Working up through the files until one does mark the surface gives an indication of how hard it is.

On one of the vee surfaces on the lathe bed shown on the sticker as hardened, the HRC40 file easily marks the surface, suggesting it is less than HRC40. Not really that hard. Whether or not it is harder than any unhardened areas I don't have the facility to check.

How big a deal is a soft bed on a light hobby lathe ? Probably not much. Do you use it hard and often enough to risk localised wear (usually near the headstock) ?

Nigel B.

Edited By mgnbuk on 03/04/2023 13:39:29

We used to use an older version of this Renishaw laser machine tool calibration system

Ditto.

I had a Renishaw ML10 laser + EC10 environmental compensation unit + a big box of optics to play with at my last-but-one employment. Beam movement due to draughts was an issue, particularly when working with long distances - the return beam could be seen wandering about in big, draughty machine shops. Long distances also showed the return beam had increased from a bright approx. 1.5mm dot that left the laser unit to a dim 5p coin sized return beam. - accurate alignment was essential to get a useable signal strength & in those circumstances a drought shop was a nightmare. No Windows 10 powerbox back then - the Renishaw software we used was DOS based & ran (via a half width ISA interface card) on an Amstrad ALT 286 monochrome laptop & a dot matrix printer !

We did have a commercial system very similar to the system in the video demonstrated at one point - probably 30 years ago. The demo was done in our works levelling a floor borer bed . The tripod mounted laser set up a level plane & there was a sensor on a base that also had a digital readout that could be zeroed. After that, as the sensor was moved about the bed next to each levelling point it displayed how high or low that point was relative to the set zero point & the levelling bolt adjusted to bring the readout to zero. It was impressively quick to use, but the boss was not impressed enough to buy one !

Impressive to see what some (clever) people can accomplish by creatively re-purposing relatively cheap, off the shelf consumer items.

Nigel B.

Last lot I got at work came from Cromwell, though as seems to be the norm now the same items are cheaper at Zoro

Nigel B.

I have an RF30 mill / drill branded TruTool, whcih appears to be the same model as the Warco Major.

The head is clamped to the column with two through bolts

The bolts just push out, the bolt head sitting in a cast pocket in the head casting LHS (viewed from the front).

The bolts on my machine appear to be 5/8"-11 UNC, 6" long. Switching units, the bolt head is 25.7mm AF & the nut 23 mm AF. The OE nut wrench sits in a purpose made pocket in the motor mounting plate.

Sorry for the rotated mobile phone pics.

HTH

Nigel B.

Edited By mgnbuk on 28/03/2023 13:32:42

I hope your comments do not put others off using it.

Can only speak as I found John.

Yes the Boko was a substantial spindle & it absolutely had a runout issue caused by that style of locknut. Fitting a KMT nut cured the issue - the issue was not elsewhere as you suggested. The abililty of the KMT nut lcoking mechanism to lock the nut against rotation without axial displacement was, I think, the reason.

If your application isn't suitable for that style of nut then fair enough. Given my past experience , I would have chosen to stick with the original arrangment. If you are happy that the split nut is an improvement, also fair enough.

Regards,

Nigel B.

I made a theaded ring with a split the can be locked in place with an M6 cap head screw.

Awful style of "locknut" those.

If, when you check spindle runout with a test bar, you find that there is a runout error - suspect that locknut first. I once spent a couple of days trying to eliminate a runout error in a Boko borer spindle that my former employer was rebuilding. New precision bearings fitted, but the spindle runout was out of spec. Tried all ways to set one of that style of locknut, but regardless of what order of assembly or tightening, the final "nip" on the screw always introduced a runout error. Fortunately the spindle thread was a standard size that was available as an SKF KMT precision locknut - not cheap items, but fitting one had the spindle preloaded to spec with the locknut fully tightened & locked with no spindle runout within 10 minutes of delivery of the SKF nut.

I concluded that the spilt style locknut nut twisted when the locking screw was tightened, causing an uneven application of thrust to the bearings.

Nigel B.

For a free 3D CAD you might want to look at NanoCAD

NanoCad is 2D, not 3D. It does work well & is what I replaced Draftsight with when they changed to a subscription model, both at work and at home. I tried both Qcad & LIbreCad before settling on NanoCad, as NanoCad handled legacy drawings from Draftsight more reliably. It is also a Russian product which, given the current situation, some may be uncomfortable with.

But it isn't 3D Cad. For that I am battling with FreeCad but am not finding the learning curve easy & I seem to be able to crash it rather too easily with my ham-fisted attempts at defining shapes. But still able to get simple shapes drawn, exported, sliced & 3D printed - eventually !

I wasn't happy with F360s "change on a whim" licencing arrangements - I didn't want to invest time & effort in something that could go the way of Draftsight with minimal notice at some point in the future & I don't wish to have dealings with the company behind SE, so not many other "Free" options for 3 D Cad. DesignSpoark Mechanical may be an option, though I don't want to be dabbling in 2 different programs at the same time - probably cause even more confusion.

Nigel B.

Finished the backplate to fit a Sanou 100mm 3 jaw chuck to my Super 7.

The backplate was an RDG pre-machined cast iron item that is a nice fit on the lathe spindle nose. At the time I bought it, the least expenesive option was a "seconds" 5" backplate that had 24 "indexing" holes drilled incorrectly. around the outer edge Turning this down to 100mm got rid of the offending holes, at the expense of the generation of a suprisingly large amount of swarf.

Drilling the 3 mounting holes had to wait until I got the second of 3 scales for the DRO mounted on the mill, which happened yesterday. With the hole pitching function on the DRO, pilot drilling, size drilling & lightly countesinking the 3 holes was very straight forward & the chuck fit on as would be expected.

The backplate spigot to chuck fit was not as tight as I was aiming for i.e. not a "snug" fit, but no obvious play. On the lathe the chuck body was running around 0.05 TIR, but that could be "tapped in" to 0.02 before fully tightening the bolts. The remaining error appears to be that the chuck body OD is not exactly round. A piece of 12mm silver steel clamped in the chuck shows 0.05 TIR runout close to the jaws, increasing to 0.08 around 100 mm out - not in Griptru territory, but not too bad for a £40 chuck & it feels noticably tighter than the OE Myford chuck.

The Jingce DRO works OK, though it would work even better if the top horizontal segment on the X axis "10s" display hadn't first gone dim then subsequently failed altogether after about an hours running out of the box. And given that my glacial work rate in the workshop means that it was sat in its box for 3 or 4 years before I got around to fitting it, no hope of any warranty (even assuming that an Ebay purchase DRO actually came with a meaningful warranty in the first place ! ). Hopefully a dry joint, but if it is a faulty component & I can't identify a suitable replacement green 7 segement display I'll swap out the duff one for one of the higher count displays - I only have 370-ish mm travel & won't use the 1000s upwards display capability.

Nigel B

Zoro list Grade 10 flanged nuts as well as Grade 8 in BZP steel.

There are a number of sellers of Grade 8 BZP steel flanged nuts on Ebay (serrated or plain).

Nigel B

I had one of these Senator Brand M3-M12 sets purchased from Zoro at work. A size down on your spec. (assuming you don't want M14 as well as M16) but they worked well & completed several large projects without wearing out or breaking any of the contents - even survived Production borrowing them for use in machines on occasion. Senator are one of Cromwell / Zoros brands.

Nigel B.

Noticed this listing on Ebay for an NOS unused Perfecto lathe while mooching around.

Shows some "patina" from storage, but may be of interest to someone ?

Nigel B

I shall clarify.

We shall have to agree to disagree on that point, Martin.

Regards,

Nigel B.

Looks like the base / table from a co-ordinate measuring machine (CMM)

The two rows of close pitch smaller holes on the LHS look like where a gantry guide rail would be attached. & the wider spaced pattern would be used to clamp the component to be measured - either directly with clamps or to attach fixtures.

In the picture above of a similar CMM to the model we had at my last employment, the guide rail on the LHS is covered, but the pattern of component clamping threaded holes can just be made out.

Nigel B.

Sorry a bit confused, are you saying I need to check the Y-Z first?

Check both X-Z and Y-Z. Only doing half the job of checking how your column lies relative to the table otherwise.

Alignments are one of those things that, to be done right, have to be done completely and in the correct order - "pick'n'mix" choosing of which bits of the alignment suite you want to check / rectify risks making other areas worse. The Schelsinger & MTB checks for machines are not just a number of checks of particluar alignments, they also specify the order in which the checks are completed. - a former colleague summed it up as "build 'em right from the base upwards".

Taken to extremes - if you use an edge finder directly mounted in a collet to set a datum on the corner of a job (head close to the table) then raise the head to get a 13mm jobber drill mounted in a keyless chuck in the spindle (say, raise the head 180mm ) would you want the tip of the drill to still be relevant to your set datum ? Your measured 0.33 / 250mm would mean that it would not be, to the tune of around 0.25mm in one plane alone - you don't know what the error is in the other plane without measuring it. Might just as well have one of the much-derided (in some quarters) un-key round column mill drills if the head alignment isn't maintained along the column traverse.

Square accuracy could be confimed by turning the square 180 degrees & re-doing the measurement - result stays the same = square OK, otherwise split the difference ? A square out by 0.33 / 250mm isn't really much of a "square" ?

The Spindle should be true to the column.

But only after the column is perpendicular to the table which, in turn, is parallel to the base.

Nigel B.

Should I rectify or is it within tolerance?

Not OK. Tolerance for a manual machine is usually better than 0.025 / 300mm (thou per foot in old money).

Did you only check in one plane - you only mention "leaning in" ? My former fitting colleagues called this check "front square" (i.e. Y-Z squareness) - there is also the "side square" check (X-Z squareness).. Both these need to be in spec. if you expect the tool point to stay true to your workpiece datum when the head is raised or lowered.

The spindle alignment check refered to by Martin is a seperate check carried out after getting the column square to the table in both planes that requires different solutions to rectify should it prove to be in error.

Pretty pointless IMO messing up your column to table squareness to fix a spindle alignment issue at, say, the head swivel interface. The notion of shimming the column to sort spindle alignment seems to have its roots in the round column mill drills, where it is not that important to have the head raise & lower truly square to the table, as alignment is inevitably lost due to the lack of an alignment key. On a guided column (keyed round colum or dovetailed), column to table squareness is just as (may be more) important than the "tramell" check with the spindle as described above.

Nigel B.