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Member postings for Ajohnw

Here is a list of all the postings Ajohnw has made in our forums. Click on a thread name to jump to the thread.

Thread: Lathe advice please
21/01/2017 22:01:44
Posted by Michael Gilligan on 21/01/2017 21:50:41:
Posted by Ajohnw on 21/01/2017 20:36:31:

MG might note that the bore aspect was mentioned after I started to post. I went away for a while just after starting it. Not that an unusual thing for me to do.

.

Happy to believe you, John ... but remember:

I can't see when you started to post; only when you posted.

MichaelG.

winkI know Michael but it's something worth bearing in mind. Rather extreme but I have even gone out for a while mid post. Unlike some seem to think at times I don't spend all day sitting at this machine. There are certain times of the day when I have a look around but the time spent on here is extremely variable.

John

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21/01/2017 21:26:55
Posted by JasonB on 21/01/2017 20:42:00:

Just read what I wrote above, twerp

"its the TR toolroom one that is the better spec"

Bit of a waste of time posting that.

Actually I was being a bit tongue in the cheek when I posted that one, thinking new and added the VSL as an after thought.

Really with questions like this size of work, budget and use is needed, Given that there will be a number of machines that would suite including many that wont even get a mention in real terms generally condition and if the accessories that may be needed are likely to be obtainable are the most important aspects. Also the fact that some machines that are available might come with all of them.

In this case imperial based screw cutting might be a good idea as well.

smiley Having shot a number of different types and ages I'm curious about which guns?

John

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Thread: Replacement tailstock, sculpture or fabrication
21/01/2017 20:38:54
Posted by JasonB on 21/01/2017 07:25:09:
Posted by Ajohnw on 20/01/2017 21:40:41:

Black bar contains a lot less stress than bright drawn but would require machining before it's welded.

I don't think I even suggested machining before welding but anyway

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I think you did John.

Good grief Jason - if I did it was for black bar. Which could be welded without but personally I wouldn't.

John

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Thread: Lathe advice please
21/01/2017 20:36:31

I said TS if extreme alignment accuracy is needed Jason. There is a fair difference in price and several different specs of the other as well some of which would probably gobble up some of the differences. As I understand it TS means toolroom spec and the main difference apart from gearbox options that by the look of it can be applied to all of them is high precision bearings. On these models if screw cutting is needed it's best to note that there are options. Some need way more change wheels than others. I haven't seen an imperial version of this machine and that aspect might be important for easier screw cutting.

I think the cam lock VSL would meet the spindle bore needs as well. Lathe co uk should clear that up. The earlier one probably doesn't.

MG might note that the bore aspect was mentioned after I started to post. I went away for a while just after starting it. Not that an unusual thing for me to do.

blushPerhaps I have the TS wrong. I'd need to check.

John

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21/01/2017 19:38:09

I assume the OP means 35mm clear bore too. However ?

If so maybe a modern Boxford with a bed length to suit or even a TS if extreme alignment accuracy is needed.

John

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Edited By Ajohnw on 21/01/2017 19:40:03

Thread: Sealing BSP fittings
21/01/2017 16:49:24
Posted by Michael Gilligan on 21/01/2017 10:04:50:
Posted by Ian Phillips on 21/01/2017 09:53:46:
For the gauge problem, use a 'nut and nipple' or compression type fitting.

.

What a great name for a Pub ... 'The Nut and Nipple'

devil MichaelG.

The catalogue I used called them breakable joints. The half with no external nut has a hex hole through it.

It's also possible to get bsp lock nuts.from 1/8" bsp and up where I looked. They have a very comprehensive range of fittings so probably hard to find.

surpriseIn brass though the start at £0.88 each in 1/8" bsp getting to £1.58 at 1/2" bsp - and £4.75 at 1" bsp. The steel ones are much cheaper.

John

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Thread: After a bigger machine vice
21/01/2017 15:42:27
Posted by Michael Gilligan on 21/01/2017 14:03:38:

Posted by Andrew Johnston on 21/01/2017 13:47:52:

A disadvantage of the commercial ones is that you need a large mill; it only just fitted on the Bridgeport. Another, more serious issue, is that if you overtighten you end up distorting the mill table in bending.

.

Very good points, Andrew

Mine are actually a pair of identical 'book-ends' with a rather nice angled slide arangement ... but yes, the caveats still apply.

I have decided they have 'potential' as the basis for special machines or fixtures, so I'm keeping them.

MichaelG.

A DW has a much shorter table length and in my case a bit over 40mm of cast iron running down the side of the table. It isn't the usual DW table. 2 T slots one along each side. Good for some things but vice mounting may need a plate.

The one I linked to is the cheap and cheerful version. Msc did stock another that was way more expensive. They mention that it grips well. Maybe it does. Only 16mm of movement but could be mounted on something else ideally with the screw holes directly over the T slots.

As my self imposed tool bonus hasn't been spent for some time due to workshop problems I've just ordered one. smiley I allow a certain amount each month. I suspect one end will more or less remain clamped to the table.

I noticed that msc also do a 200mm version of the other vice mentioned.

John

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21/01/2017 13:32:59

I've done lots of bits and pieces using a record drill vice. The small one that was popular for use on Myford vertical slides. They really need attention to the alignment of the jaws especially the fixed one but hold well enough.

It was permanently fastened to the table most of the time. While nosing around on ebay I saw one of these used and at a decent price.

**LINK**

Crazy design, just look how thick the fixed jaw is compared with the cast iron behind it but I think it will be fine for light milling and more flexible use wise than the record one. Guess they did it like this due to the strength of the base. It wouldn't be suitable for hefty cuts but is well made.

I also have a conventional 4" milling vice. It would probably be perfectly happy on a 5hp geared milling machine. That in my view limits it's opening capacity.

The worst type I have ever seen but it could be a bad example is the small ones that tilt with a metal strap on the side to hold it at a set angle. It came with my dore westbury and if the person who sold that use a decent vice on it and didn't end mill with a blunt slot drill he may have been a lot happier with the machine.

If I needed to do bigger stuff I would probably add one of the 2 piece ones to my kit hoping it has removable jaws. as that's not a bad idea on any machine vice.

John

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21/01/2017 11:50:39

This is an example of the other type I mentioned

**LINK**

Mscdirect aren't always more expensive. That is pretty variable on all sorts at times.

John

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Thread: Online suppliers of M42 square HSS blanks please?
21/01/2017 11:16:19

I'm pretty sure Crobolt is another stellite type as per Tantung. I think that drillservices uk did or do stock some stellite. Sources for this sort of thing in the uk seem to be scarce.

John

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Thread: After a bigger machine vice
21/01/2017 10:53:36

It's possible to buy ones that come in 2 halves that are fastened down in the T slots on the table. I've been tempted several times but good ones are usually rather expensive.

It's possible to use the arc one shown in the photo without the rotary base - more headroom if needed. The jaw faces can also be repositioned. As they can be removed soft ones could be made to machine as needed. Also given that we generally have lower power machines larger ones to fit on the opposite sides of the jaws.

cheekyArc won't let me post a direct link to the image that shows what I mean to stop others pinching it. It's image 4 on this page

**LINK**

They may be available at larger sizes some where. MscDirect did have them as well.

I have mixed feelings about the downwards force aspect.

John

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Thread: Sealing BSP fittings
21/01/2017 10:15:42

Yes the gas spec one is thicker and seems to be usually supplied on a yellow reel. Just 1 1/2 laps should be applied in a left had screw fashion if it's on a right hand thread. Also may be marked high density.

Having used it I think it's an "improvement" we can do without and it still shreds anyway and behaves almost like it's been pre stretched.

surpriseYou might gather that I have used it and wasn't impressed. I've used the other stuff a number of times and when undone no signs of shredding but different type of joint.

Eihell had used it on the euro coupler supplied loose with the compressor. Their answer was to use the right width and a bit more of it. Result - wont actually go into the female half and finishes up as a sort of ptfe O ring. Not much more either. It might be ok on bigger fittings over 1/4 " bsp. I have seen it used on a cooker hose but it didn't stretch into the threads like usual stuff does.

Parweld use a liquid ptfe. It looks like the screw things in until the taper nearly meets and apply a tiny drop of it. Having undone one I think people would be rather surprised how much effort that took. Maybe the loctite one is better but it's too late to find out once it has been done up.

John

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Edited By Ajohnw on 21/01/2017 10:16:49

20/01/2017 22:47:06
Posted by John Stevenson on 20/01/2017 22:38:50:
Posted by Ajohnw on 20/01/2017 22:28:48:

. I'll stick with tape but cut it to 1/4" wide as that should help

John

Do like real engineers do and just fold it double as you wind round.

Simples but if it was harder you would need a new thread, keyboard and armchair.

Tried John it makes it more difficult otherwise I would have done it that way.

John

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Thread: Replacement tailstock, sculpture or fabrication
20/01/2017 22:44:35

The other way with some other tailstock would be to get one even with a lower centre height but with the right size of quill, machine of the base and make a new base for it.

It would need some nice fitting to get the centre height smack on. I think I would be looking for way to drill and ream it from the head providing that is ok and pointing dead straight down the bed.

wink I have an old 4 or 5" tailstock of a well know german plain lathe that I scrapped off. Kept in case I ever needed to make a larger dividing head. Not an ideal candidate but could be done fairly reasonably.

John

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Thread: Sealing BSP fittings
20/01/2017 22:28:48

I tried the slick tight on one joint. It's an amazing lubricant. The female part went on so far I was concerned about something stripping but it still tightened solid eventually.

The brush built into the lid would be more suitable for much larger fittings - say 1" od pipe or more.

The regulator on the compressor is diecast so don't think I will be using it there. I'll stick with tape but cut it to 1/4" wide as that should help and any bits over 20um get trapped by the filter from there anyway.

Don't think I will ever buy any titanium coated drills again. As my metal work gear is rather packed away I used my woodwork ones. Not cheap. To refit the filter in the pipe tail on the welder I had to drill the hole out as the serrated part has been cut off. Brass and even extreme pressure wouldn't cause the drill to cut. The hole was a bit too shallow really and as I had the fitting off I managed to get my hands to my metal work ones - woosh I nearly drilled too far. The drill even grabbed in the brass. I had wondered if it was some sort of bizarre material.

John

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Thread: Replacement tailstock, sculpture or fabrication
20/01/2017 21:40:41
Posted by Nicholas Farr on 20/01/2017 20:36:26:
Posted by Ajohnw on 20/01/2017 18:53:29:

I've never heard of stress being a problem when things are produced like this. Effectively the casting is fabricated and then machined much like the casting would be.

Black bar contains a lot less stress than bright drawn but would require machining before it's welded. As far as I am aware and I have seen a number of example all were done in bright drawn.

John

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Hi John, stress relieving is not uncommon for welded fabrications, but is not always needed. However, fabrications made with black bar or plate and sheet steel and also bright steels and stainless steels are virtually always machined after being welded and any stress relieving needed. As welding will always cause distortion, whatever you do to try and prevent it, any machining will be pulled out of shape after welding.

Regards Nick.

I don't think I even suggested machining before welding but anyway I made a posting a little while ago pointing out the problems with producing stress free castings.

surpriseIt's vanished into the aether. Hope it wasn't because I gave a clue about where that rotary table casting came from and pointed out 2 suppliers that for me have been ok but it can take years to find out if they are really ok.

Also mentioned the time Rolls Royce left engine blocks lying about - lathe manufacturer's castings too. Plus some of the problems of stress relieving things via heat.

John

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Thread: Online suppliers of M42 square HSS blanks please?
20/01/2017 21:13:10

Tantung G can be bought directly from the suppliers but I don't know what the prices are like. Interesting fact. Hardness wise if like some grades of stellite it might be a touch less than HSS even M2 yet wears better and can cut at higher speeds.

John

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20/01/2017 19:18:30

You might like to look at this Jon. I looked because I had a vague memory that there isn't that much difference in hardness.

**LINK**

I have forked out for M42 and as far as need for sharpening I really don't think there is any significant difference. Last time I bought some it came from the USA.

John

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20/01/2017 18:57:08

You might find M42 is available from Cromwell Jon but their toolbit section is a pain to look through. When I have bought from them it's usually from the clearance section. There are usually a number of tool bits types in it.

John

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Thread: Replacement tailstock, sculpture or fabrication
20/01/2017 18:53:29

In the past when castings were being churned out for tooling described in the latest model engineer mag etc some people wouldn't buy them and fabricated instead. Castings need to be cooler rather slowly and left lying around for a long time to remove stress. It can be a big problem on tooling. I have a home made rotary table that came with my miller. The casting had distorted enough to prevent it working correctly. I took a strap off it and the casting cracked. Curiously the top and bottom is still flat so it still works. All I had to do was relieve it in parts to provide sufficient clearance.

The usual method of fabricating was mild steel and arc welding usually using automotive body filler to form the blend between parts and then painting. Arc welding is likely to be the best option as it's relatively easy to get high levels of penetration and a strong joint. The added material also tends to be applied in several runs which will result in a fillet like shape that might also require a bit of machining.

I've never heard of stress being a problem when things are produced like this. Effectively the casting is fabricated and then machined much like the casting would be.

Black bar contains a lot less stress than bright drawn but would require machining before it's welded. As far as I am aware and I have seen a number of example all were done in bright drawn.

John

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