Lathes : Weak-Points

[John Stevenson 1Participant @johnstevenson1]

Posted by Ajohnw on 19/02/2016 20:16:01:

Hands up.

Who on here have used say for instance a Lang Toolroom or a Colchester Student that hasn't had many hours of even light work done on it. Say 2 weeks max and by no way continuous and oiled well each week even if it's not been used.

Anything similar would do. Very top end such as the Lang and middling such as the Student. Or anything in between.

John

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That's anyone who has bought a brand new lathe then as it gone from brand new to used, to well used.

So thinking about it I have owned 9 brand new lathes over a period of time but what does that prove ?

[Nigel BennettParticipant @nigelbennett69913]

Chris

The Gibraltar Toolpost was dreamed up by Tom Walshaw (Tubal Cain) in ME quite a few years ago. It replaces the Myford top slide with a big cast iron toolholder, which removes the play inherent in a topslide so as to increase rigidity. I imagine a search in one of the on-line ME indexes would find it.

I described one in ME a year or two back to fit the Myford-Dickson toolholder in a slightly lower position than can be accommodated on the standard Myford topslide-mounted arrangement. It allows the use of 12mm tools, which the toolholders can hold, but you can't get them low enough on the topslide to use them!

Obviously turning short tapers is not practical with a Gibraltar-type toolpost.

[Nigel McBurney 1Participant @nigelmcburney1]

Back in the 1960s I took a toolmakers job, there were two of us in a brand new toolroom,looking after and maintaining special purpose machinery, there were two prime machine tools , Deckel FP3 mill and a CVA toolroom quality lathe, there was even a full leadscrew inspection. chart, Both machines were absolutely first class,the Deckel I really looked working on, The CVA was very accurate and produced accurate work,but I never felt comfortable with it, its like a Bridgeport some like them some hate them. Of course machines of that quality were looked after.and used by apprentice trained personnel. Nowadays that kind of training is rare,so many comments are made on posts by the unskilled. The moan about the Myford cross slide goes tight when bolting a job to it for say milling or boring,well what does one expect its only a small piece of tee slotted cast iron, care must be taken,its not the lathes fault its the operator, the 50 inch table on a big turret mill will also go stiff on its slides if the clamps holding a job are too tight, particularly when long strap clamps are used.

[AjohnwParticipant @ajohnw51620]

I can't see how anyone can rate a lathe unless they have used lathes in this sort of condition and also ones at various states of wear. I have. The Lang and also a DSG with toolroom in the name are probably pretty rare but I have also used a lot of other brands in various states of wear and with what might be called initial states of quality.

Not boasting or anything else like that but when people say they have a wonderful this or that I wonder how they know it's wonderful or even what they mean in practice when they state that sort if thing,

Just curious really because I know there is zero chance of me having a lathe at home that is anything like some I have used. Probably not even a Student as like many wear shows in a surprisingly short time when they are really used.

There are some things that irritate me performance wise about my Boxford but no point in mentioning them really as it's a Boxford. A brand new one might resolve these irritation or more likely some of the new ones might but that state of affairs wouldn't last long. The same is true of many lathes even bigger ones.

John

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[AjohnwParticipant @ajohnw51620]

My training was like that Nigel, but one mistake and no more progression. That's how a place can finish up with something like a Lang Toolroom lathe that's been there for some time yet only had days of light work done on it. I had a bit of 1/2 bar to turn up to something on that one. It took a few hours. Initial work was things for the toolbox. That was used to sort people then odd ball more interesting jobs passed on from the factories.

Officially I didn't get to use the CVA. I had a name for being heavy on machine tools if needed and they were worried I might spoil it. Fat chance within reason. My father loved them. He had a room set up with 1/2 dozen of them in it for production use when needed. Making obsolete car parts. Precise, long lasting and a small footprint. Even these get worn well past anything resembling precision as they all do eventually. I suppose luck might turn things up from time to time but lathes and other machines tend to have the jobs that are done on them changed as they wear.

In real life many things made in toolrooms are hardened and if precision is needed anyway the work finishes up on grinders. So much for my training but it all changed not long after I finished.

Really the slightly worn and worse ones are in some ways they ones that need most skill to get the best out of them. But " slight and worse limits what they can do without further corrections. Super duppa stuff all comes down to how tools are ground and speeds and feeds. That area is why I have no respect at all for the usual tables. Even the lathes themselves vary.

John

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[John Stevenson 1Participant @johnstevenson1]

Well I have had two CVA's, neither new but both well looked after and there is nothing finer.

It's an anomaly why in the UK they never fetch what they are worth, you can buy one easily for 1K yet people will pay 2.5K for a clunker of a Colchester I wouldn't give yard room for ? Perhaps like Bridgeport and Myford, it's the name. ?

[AjohnwParticipant @ajohnw51620]

Must admit I was rather surprised when some one posted a shot of the headstock bearing arrangement Colchester generally seem to use. I expected better a la cva and some other Brit lathes also Schaublin. Plain bearings can be be better but wear is more of a problem. The worst lathe I used in training was a Chipmaster. Spent most of it's time running at 3,000rpm doing small work and not all that much of it really. There is not much scope for taking bigger cuts to get rid of surface finish problems on small work. If lathes need to run that fast they really aught to change the types of bearings used at this sort of spindle size.

My father could probably have obtained a selected CVA for me cheaply. One aspect that worried me was the weight but the main one was the usual bits and pieces. The training one was fully equipped including coillets and a fancy screw cutting indicator that would also cope with metric. Gears for DP and Mod too.

Myford popularity is easy. A budget lathe and many years of mags showing all sorts of things that can be made on them – sometimes suffering as a result. I'm thinking of things like the College Engineering rotary table kit. Originally designed to be made on a Boxford or larger. Slimmed down to get in the myford gap. For me a Raglan is a much better machine with that style of bed and cheaper used too. I think all of those have hardened bed guides but may be wrong. The make died when Myford bought them out. They even have variable speed without messing with inverters. They can be reconditioned as well but the unworn part of the rails which are fastened to the bed needs clocking up extremely precisely and it would probably pay to have the underside of the saddle licked over as well. The cross slide on mine was fine. The actual bed wear it had wouldn't bother most people but I don't have a cylindrical grinder. The attitude comes from using certain lathes in the past. I can't get rid of it.

Most milling during training was horizontal, things like V blocks, rather large twist drills, gears and other bits and pieces. I did use a 12" face cutter on a very hefty turret miller and a few jobs like that but better results would have been obtainable horizontally on the right machine. It was 2 long heavy V rails for a machine. They went on to be ground anyway.

I have used a Bridgeport in my own time at work. My impression was a bit light weight for the table size but capable. I suspect fame came from various gizmo's. This one was fitted with optical scales, viewed not digital so people could use it as a down market jig borer / set very precisely. In a small workshop along with various welding set ups a decent pillar drill and a Harrison like lathe. None of it used that much. I can't remember the makes of some of the lathes that I have used but this one had the essentials, bed guides nice and long and could pass either side of the headstock and tailstock. Nice long head – good for alignment, whisper quiet gear head and a sensible range of feeds. Wear wise it was at point where a certain depth of cut and feed rate combination was needed for best finish so would probably be turning a bit of a taper. Some one made a snooker cue on it by offsetting the tailstock. Afterwards it was low by about 1/32 or so. I'd guess the some one lost some shims but he reckoned not, It was smack on before that as far as I could tell.

I wish I had space to set my small shaper up – a very under rated type of machine when people aren't in a rush. The equivalent of a lathe in some ways but for flat work. It can be extremely flat too.

John

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[MWParticipant @mw27036]

Posted by Chris Evans 6 on 19/02/2016 20:41:58:

Michael, can you please give me more info on the Gibralta toolpost. Chris.

Hi Chris,

Like Nigel Bennet said, it's a cast iron tool post, quite big and as tall as the centre height of the lathe with a hefty cutaway for a large turning tool, could go up to a 1" tool. You would remove the top slide from your T slot base and replace with the gibraltar tool post which could give you a large amount of overhang towards the headstock, meaning that you dont have to move the table as far in order to reach it, which would be handy when it comes to those pesky facing/boring to long depth jobs, the fact that its a solid piece of cast iron means it gives you maximum rigidity without any worry of vibration/deflection at the cutting face., that you might otherwise get from the top slide.

Hemingway kits do one for the series 7, **LINK** but, if it were me, i'd see no reason why you couldnt adapt this idea and make some patterns for a casting that would match you own machine, or even modify the existing kit using barstock.

Michael W

[Neil WyattModerator @neilwyatt]

Posted by Nigel Bennett on 19/02/2016 21:57:19:

The Gibraltar Toolpost was dreamed up by Tom Walshaw (Tubal Cain) in ME quite a few years ago. It replaces the Myford top slide with a big cast iron toolholder, which removes the play inherent in a topslide so as to increase rigidity. I imagine a search in one of the on-line ME indexes would find it.

Gibraltar-style toolpost for mini-lathe that replaces the top-slide but retains the 4-way toolpost or allows use of a QCTP:

[AjohnwParticipant @ajohnw51620]

Pultra 1750, 1770. Adding to Michaels post a little. Not exactly problems just factors.

The headstock bearings look like they are easily adjustable via nuts on each end. In practice these close the bearing down hard onto a laminated shim.

Makes adjustment interesting as there will be some wear on the spindle so I suspect it was a case of remove the lot, remove a shim, clamp it all up and adjust hole size to suit the spindle, Take apart again and re assemble.

There are variations.

Some have a thrust race to take up spindle end float. Others have a sleeve instead and the spindle has to be adjusted so that this runs up against the ends of one of the bearings. I suspect this type is the one that was cleared for 10,000 rpm use.

Some may have conventional gib strips on the slides rather than the taper adjusted type.

Some 1770's use a 1750 head fitted onto a suitable riser block. Going on the ones I have seen these will have the thrust race and the taper gib strips. Suspect both are down to S&B.

It's possible to move the cross slide well out from the bed for large swings and fit the normal riser blocks to both models which pushes the centre height well up – I'd guess this is how things get broken. I don't think that the lathe is suitable for anything other than extremely light work when it's use like this.

They used to make attachments for these machines on request. I suspect that if some one asked for something along the line of screw cutting, chasers or via gears they would mount it on the nicely machined flange under the end cover. That might explain why there are so many tapped holes in it. Might make a nice project for some one with one.

John

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[AjohnwParticipant @ajohnw51620]

Posted by Neil Wyatt on 20/02/2016 18:26:30:

Posted by Nigel Bennett on 19/02/2016 21:57:19:

The Gibraltar Toolpost was dreamed up by Tom Walshaw (Tubal Cain) in ME quite a few years ago. It replaces the Myford top slide with a big cast iron toolholder, which removes the play inherent in a topslide so as to increase rigidity. I imagine a search in one of the on-line ME indexes would find it.

Gibraltar-style toolpost for mini-lathe that replaces the top-slide but retains the 4-way toolpost or allows use of a QCTP:

I didn't know those came with a T slotted cross slide Neil. Surely you didn't make it on it via a Taig vertical slide.

John

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[Chris Evans 6Participant @chrisevans6]

Gibraltar tool post. Thanks all for the information on them. I have just had a casting made to enable me to replace my weak cross slide. I will look into making a tool post and try to use it on the fixings for a radius / ball turning attachment I have also had cast.

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