Member postings for Ajohnw

The idea of the dowel is to stop the gib strip sliding back and forth as you move the slide. Fitting one is exacting work and could easily finish up worse than it currently is. You could hold the screw in the 3 jaw and file a rad on the end. Ball end like. It will be a better match to the dimples.

The edges of gib strips are usually angled. If so it is possible to put them in the wrong way round. If radiused, chamfered or of a such a width that the angle isn't needed they can go in either way. The edges need to be slightly clear of the castings. If the edges are angled chances are they will foul if put in the wrong way.

Check the edges as per this

There is no problem associated with using the correct type of linishing machine for this sort of thing. The male half of the slide should also have a narrow flat on it's peak.

If you do use a kitchen abrasive cream with oil to lap the slide a little it will probably be easier to remove the nut rather than the lead screw. It looks like it's fixed in place via a screw under the compound slide which will also be easy to remove. Forget mention of serious lapping. All these abrasives will do is lap minute amounts of metal off helping smooth out machining marks. It probably wont get rid of them. They are more like coarse metal polishes really that will leave a polish. If you were in the uk I would suggest CIF which is a cream mixed with some 3 in 1 which in real terms is a light cycle oil. You may need to spend 10 to 20mins or more to get a smooth even drag when the slide is pushed by hand. Then clean up and oil them while they are apart. The nice aspect about removing the lead screw is that the gib can be adjusted correctly and easily while pushing the slide by hand. It's easy to feel the slight drag that is needed this way. It's easy for people to over tighten when the actual lead screw is used to do this.

I wouldn't advice using coarse abrasives. It can be done but once again it's easy to mess things up and will probably result in a gib strip that needs replacing.

John

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If they had been ground the machined surfaces would be mostly nice and shiny. The bed on your lathe will have been ground. Looking at the photo I'd assume that the male part has been ground and some tool dabbed on it to make it look like it's been scraped. The female part looks like it's just been milled however the Chinese have used a form of linisher in the past, emery cloth belt that is rotating. These linishers are a bit more "technical" that the usual type.

John

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It looks like the screwfix one's have all gone. Odd them not restocking them as lots of rave reviews.

These look to be the same ones

**LINK**

John

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You could try the treatment mentioned on the Oz Taig pages Brian but don't use anything coarser than they suggest as that might make things worse. Why- from the photo's I can't see if the slides have been ground or just machined. In either cases there can be some degree of roughness to the surfaces - this will wear off much more quickly than the bulk area of the slide's surfaces leading to tight spots.

A common problem with earlier chinese machine was sharp edges on the male part of the dovetail and these fouling on the female part. There should be a narrow flat running along the sharp edge of the male half. Reason - it's rather difficult to ensure a dead sharp corner in the female part. The flat only needs to be say 1mm wide.

John

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A tap on the end also works Vic. The thread is turned off for a moderate distance on the end of my draw bar.

I went for them because the min shank size for a typical to 16mm milling chuck had always been 3MT. I have seen those get bent too, I probably wouldn't do that but that sort of size on a 2 morse shank doesn't make much sense to me. These days all sorts can be bought with 2morse holding it.

My miller is a dore westbury and has a myford spindle nose so anything bigger than the bore size of a 2morse collet would best be held via that. The actual quill is pretty substantial.

John

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I'm going through my ticks John. It very much looks like if I want to increase the size range of my work holding collets it will be spring collets and not ER. For tool holding yes ER.

Some of the decision comes from doing a fair amount of collet work but not at home. I don't purchase the wrong thing very often. I have a Bernerd multi size that will match ER40 but has the same problem so it's never been fitted. I bought it because some one who was giving up came along and offered it to me for the same price as Rotagrip offered him. I have also sorted the mounting info for it.

I don't really have any need for bigger work holding collets at the moment but I do need to sort out tool holding. As I have them I'm going to try ER25 with a rather large tool on the end.

Thanks for the thought on holding screw threads for studs John and maybe other thing. Makes me wonder if I can obtain some 3C emergency collets. Rare I suspect so probably stupidly expensive. I'd guess I could do the same with 3 morse blank ends but splitting them would be more work,

I'd beg to differ on 5C and similar types in the UK. Often they are collets designed specifically for the lathe they are on rather than a standard type like 5C but cost has tended to rule them out in the past. It's not so bad now but as I suspected I can buy a 5C collet chuck from the USA that has a sort of spec with it but not in the UK again - other than one seller and the spec was pretty bad. I'm getting pretty cheesed off about that. It's as bad as Ketan's motor power one. CTC is an alternative on ER.

As to the rest I thought it was worth mentioning as the reasons for the difference are real and not some ones imagination. What people choose to do on that score is up to them.

John

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The Crawford catalogue is on line and gives their tolerance - also rather clear about intended use.

The trouble with variable sized collets as against spring types of a specific size is that they need bar in them right up to more or less the full length of the collet. Spring collets will generally work with a shorter length in them. They don't give the sized socket lengths in any info I have though so the comments might be a load of junk. I'd guess that the grip length of a spring collet will be about 1 1/2 to 2 times the diameter it's intended to hold. However - Measuring a 3C it's not far off 2 diameters, a bit less.. So for instance an ER 40 is comparable when it's holding 23mm. ER16 when it's holding 14mm. Spring collets such as 5C type are also reckoned to be happier gripping short than intended lengths. This is why this style of collet is sometimes referred to as work holding and the other bar holding - including Bernerd multi grip. Where I come from that would be called a bar chuck not a collet chuck.

Here endeth lesson on collet technology. It matters to me due to flexibility in use. The 5C type will still hold bar type work.

John

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I use er and morse collets plus draw bar. I think people are inclined to forget morse and that is what is providing the drive to any chuck anyway. Just need the ones to suite cutter sizes. One of the reasons for using morse is that it's a 2 morse spindle and that gives me the best rigidity. I also use an ER16 collet chuck more to be able to see what I am doing easily as the quill has a fairly large dia.

I've recently bought an 100mm facing cutter. That means I need to go bigger on shank size really so will probably add ER32 for up to 20mm in a few sizes, or ER25 which will hold up to 16mm. I'm not sure the extra 4mm on 32 is worth it as I have the ER25's I need anyway.

I've found that if the er collets max size is the same as the cutter they don't drop out. The 16's are by Vertex. Ball bearing closing nut ? Maybe if I find i need it which I feel is rather doubtful.

John

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Just returned from the Midland Model Engineering Exhibition. It was extremely busy in the morning but did slacken off a bit around 1 - 2 pm. Not much signs of show specials. I haven't been for a number of years and didn't think much of that or where they hold it now - bit cramped.

My wife came along and as expected was fascinated by the models on display. Me too and my son. There is some excellent work about.

I took the opportunity to look at a number of rotary tables. Odd that the worm mesh is limited on them so if I need to go bigger than the one that came with my Dore Wesbury I will be completing a larger one that I had started on. Main reason for stopping was the lathe I was making it on plus need. I did see one that might be the same as another one I have. No worm wheel, just angular stops and a handle to turn it round to mill curves. Probably home made like mine and cheap. They are a bit small but I've always thought I could simply fit a larger table if needed.

John

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The Vertex site specifies the run out some distance past the end of the collet. In other words the error at the tip of a tool or piece of work that is sticking out of one is given directly at the length they specify. This is how it should be done. Others say anything from 1 to 15um run out but don't say where and I very much doubt if it is where Vertex specify it. More likely some where actually at the collet which doesn't say anything at all about the run out in use.

Plus of course UK sellers generally don't state anything at all. even ARC.

I've been here before with ER25 and finished up buying from the USA where they do generally state something even on ebay. I asked for some clarification in the correct terms and was told that a number had been checked and found to be much better than the standard tolerance so decided to trust him. These were spec'd as better than 0.0005". The seller had complaints from his customers in the past. Not with this batch.

I'm slowly coming to the same conclusion as John K. They aren't really suitable for lathe work, more bar work especially as the size goes up. My Boxford lathe collets are a bit limited on size so I keep wondering about obtaining larger sizes some how.

John

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One mod I intended to make but haven't is to angle the tool bit holder, say about 15 degrees. Only problem is that if some one happens to have a drill pad for the tail stock it's more difficult to get the bit hole for the bit on centre in the holder.

The holder could be set up in the tool post and drilled. Say in a qctp boring bar holder.

The one I use now has a rod end as one bearing. Home made. May as well buy one less the usual spherical bearing no time to think if using a spherical one would cause problem. I'm off out.

John

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I had a problem like that. Screwfix fixed it. They aren't restocked any more but many branches have them. I was rather surprised by the quality and price. They should be big enough and they come as a complete set.

John

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I broke a tooth of a Raglan doing it Jason. It can happen. Mild steel and cutting a key in one of the variable speed pulleys. When I bought the lathe I found one of them was cracked. Lathe still worked ok so made another.

John

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Edited By John W1 on 15/10/2015 09:27:36

That method needs a warning - a great way of breaking a tooth or two off the rack feed wheel. tt's probably ok with light cuts and narrow keys on soft materials.

I made something like this years ago and have even used it to gash silver steel. Not needed all that often but very useful when it is. The one I made went with a myford but the boxford came with one at the correct shaft height.

**LINK**

It was based on a casting but not this one just similar with simpler lighter linkages and a flat lever.

**LINK**

Too late to post a photo.

The hole for the slotting head is drilled and reamed with the casting or block of metal etc fixed to the cross slide so that is always on centre. Some one on here made one that fitted onto the toolpost recently to produce some straight knurled knobs.

Your right to wonder about setting the slotting tool height. If it's going on a commercially made spindle the key on that will be dead central. If you cut one on a pulley and go for a precise fit and it's off centre they wont fit together and out comes a file to correct it.

The best bet is to turn up a bush, slot that and check that it fits on the spindle then do the pulley when your sure it's ok. That's probably what he did.

Oh - it's also possible to slot a shaft but care has to be taken to make sure it doesn't get bent.

John

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Edited By John W1 on 14/10/2015 23:38:54

Edited By John W1 on 14/10/2015 23:41:24

A rather large range of pitches have been used on metric thread Rod. If I remember correctly a site by MarylandMetrics or something like that list lots of them.

I suspect a lot of knowledge has been lost concerning lathe gearboxes and conversion gears. I started on the basis that the person who originally bought the lathe along with other bits and pieces may well have been aware of what to buy for what he might need as he may well have been around long enough. I don't think there is a better arrangement than the one I posted using the gears he bought. Haven't tried DP or MOD yet. Another example is just why boxford chose to use on specific value of gear for packing which they appear to have done - it allows some moderately accurate metric threads to be cut.

It's pretty natural that a USA designed gearbox and the gear range that was provided with it will be capable of cutting a number of things that aren't "USA" and companies seem to favour very close approximations rather than exact conversion gears. Even Colchester for some time. CVA did offer a 127 based conversion gear but as far as I know in that period few did.

My wabeco is metric. I decided to go for a true metric 2nd lathe for fun. Unfortunately due to a "continental oddity" I will have to make a screw cutting indicator. No thought needed at all if it had a 3mm lead screw. They have used 5mm - I think from a quick measurement when I bought it. Maybe they don't over there as it gets rather cumbersome to cut some this way as the indicator takes a long time to come round. The boxford one will cut a fair number of the usual ones.

The Pultra is an indulgence. I've wanted one since I finished my apprenticeship.

John

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Here is one of the few examples of the way that collets should be spec'd that is also meaningful.

**LINK**

They will also assume engagement along the full length of the collet's socket. Bit of a difference isn't there even with best precision.

Sorry Neil that answer is no good to me - I suppose I could lap them as I use them. Or do what ever that article suggests.

John

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I've been thinking about buying larger er collets ER40 in particular. I am aware that they need a certain length inside them that will be longer than a conventional type in order to meet their spec.

The spec is proving to be the problem or lack of it. DIN blah blah is often mentioned great they all have the same shape. Looking at the lower cost options a run out spec is given in many countries but seldom in the UK unless they are being sold from the far east. Some even say well what you get might not look like the photo. It's even possible to pay hundreds of quid for a set that doesn't mention any spec. The Vertex spec's on their site look worse than some but the do appear to be measuring them some distance from the end of the collet as they should. That makes me wonder if some are just measuring the run out of the start of the bore.

Anyone found an answer to the problem?

John

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TUV did get involved in fishing line some years ago. A commercial nightmare for both manufacturers and retailers. They actually published real figures. The hype in this area relates do line diameter and knotted and unknotted breaking strain even wet and dry. Very similar to your problem. In this case I would guess that eventually the manufacturers thought better to not head in that direction and just continue as usual. One particular make of line became weaker. They may still do this sort of thing on any product.

There are supposed to be advertising standards. I feel they are a bit of a joke in some areas. As a designer I have often been asked to rate a problem on the basis of who will notice it, expert, some one with limited knowledge of what ever it is or joe blogs etc. Then come conditions, likely hood, severity etc.That's life these days in many areas. Marketing is probably similar. I know sales are.

One thing that might not have struck you is companies might over state the motor power and not even allow the motor to run at that level. It's no worse than using input power as far as use of the machine is concerned. How on earth would a typical newbie to lathes know. They are probably completely un aware of the torque characteristics of electronic variable speed drive as well. That aspect in it self should make people wonder.

John

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It's similar to Ketan's post Brian. I'm sure I have seen older sewing machine motors that give input current and output power. I spent some time looking around to find something suitable - then suddenly remember a couple of sheep shearer motors I bought some years ago. I only mentioned them as sheep are sheared all over the place so people might get lucky. I'd guess that they are a bit expensive if bought for repairing one.

I bought a much larger one recently off ebay. Didn't know it at the time but when I asked the person selling it some questions they said for sheep shearers and they had been on the shelf for ages so he wanted to get rid of them. Too big and heavy for toolposts but I am not entirely happy about the drive on my Pultra. The other option would have been a treadmill motor - it looks to be cheaper to buy and entire broken treadmill locally than a used motor off ebay. These are over rated in terms of the power they will give. Some put current, volts and power on the plates or labels.

John

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Edited By John W1 on 14/10/2015 17:06:22

I very much doubt if that style of meter off anybody can measure true rms correctly unless it's a pure sine wave draw. I must admit from the the frequency range spec of the 317 it's better than I would expect but it could still not be good good enough to give accurate readings when the draw is pulses / lop sided etc.

I thought the brake related to the link - silly me.

There is another silly aspect to the test the link shows. The power of a lathe motor isn't when it cuts out. It's when it can do several hours of work with very short breaks without cutting out. The problem with motors is that work heats them up quickly and they loose it more slowly. That needs including as well really. It's a common issue with diy tools.

One answer to Ketan's problem might be to involve these people

**LINK**

I've no idea what the costs would be but it could be an answer that would stop the sort of things that are going on. The lathes probably already go through some approvals so it would be a case of establishing realistic physical factors should they offer to do some form of approval procedures on things like motor power and other aspects. They could do this sort of thing in the past and have done. Not sure currently. I've only submitted things to them to prove that an adequate approach has taken to produce a reliable product that should work without problems. Mostly technical talk and a walk round. Safety critical stuff in other words that they could not realistically check themselves.

John

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