Member postings for Ajohnw

Any more info on the paints used David - do you mean artists oil paints and solvent based varnish such as the exterior grade stuff?

John

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Nitromors is pretty nasty stuff fume wise so I would use a scratch brush on an angle grinder plus a dust mask.

If a machine is painted by a pro they spray on a high build primer which will leave a nice smooth coat and mask any casting mottling etc. When I have done this in the past the priming has let it down so I'd guess some sanding and maybe a couple of coats at least might be needed,

One trick to obtain a very high gloss finish is to use Techaloid and thin it with white spirits but it will take days and days to dry out. I've also polished brush marks out with automotive cutting paste but again more than one coat is likely to be needed - I did that on a morgan type kit car once. It took 3 coats and a lot of elbow grease.

John

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No point asking me I have only used 10in dia ones on rather large machines and have hand fed. Never at home. I have been toying with getting one for my dore westbury but am not keen on the price of re tipping the ones that take a lot of inserts. I'm inclined to try one around 3in dia but wouldn't expect to be able to take much of a cut with it. That takes 2 morse but also has a myford spindle nose so I would have to make something to fit it on that.

I'm pretty sure you will find a demo of face cutters using your machine on youtube and can get and idea of size from that. I'd guess w20 arbours are bound to be available. It's a schaublin design.

John

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Egg on my face. The ones I have are helical - over 1 degree less than 2. Mislead as I have seen info on making straight rack form hobs so assumed that they would be like that, also gear shaping and at first sight they look to be straight cut.

I'm going to have to try using a slitting saw slot to guide them with a freely rotating blank. This does work when taps are used for making worm wheels but the lead angles are usually much greater so I'd guess it wont work with these at all. When worm wheels are made like this people claim they turn out correct without the gashes but I would be inclined to put that down to luck - if it happened at all.

Dammmmmmmmmmmmmmmmmmmm!

I did realise that without rotation they wont produce perfect teeth but think that they would be usable.

It's not difficult to make hobs that are just a rack form eg

**LINK**

I think that there was some one around in the UK once that had a vacuum furnace making then in HSS mainly for clock making. I doubt if I have the link any more.

John

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It's worth adding to that. Usually the words dilute to excess are used with any acid when this sort of thing is mentioned. What that means in practice is into a LOT more water and I do mean a lot compared with the amount of raw acid. This can mean stirring and adding relatively slowly with very strong concentrations. Stirring anyway.

Neutralising needs some checking as well. The reaction can be violent in some cases. Best check an MSDS there will always be suggestions. Interestingly disposal usually involves burying as acids generally break down to harmless substance pretty quickly.

John

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It looks like an aluminium pulley so be careful heating it as it might melt. A hot air gun would be a lot safer.

Most people seem to thing 1/2in / 12mm or bigger all thread is best, BSF of metric coarse and a big spanner or 2.

John

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That's pretty obvious Steve - that's why they are straight cut and not helical which might be used for worm wheels.

People who make worm wheels at home usually gash at the worms lead angle to serve as a guide and then use a tap to finish it off - or just gash to the rack form. Some just use the tap but the tooth count doesn't always come out correctly

John

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I might regret buying them then Rod.

I can't see why that should happen though. I did realise that straight indexed cuts with them will produce gear teeth with an incorrect tooth shape but I doubt if I would ever buy a complete set of the ordinary form cutters so would finish up with incorrect teeth anyway even with the usual part set. In both cases I suspect that a bit of lapping would clean things up if needed.

One thing for sure if diameters and cutting depths were out the wrong way a hob will cause problems.

John

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The whole idea of the switched capacitor start motors John is to provide sufficient torque to get all of the parts on a lathe spinning and up to speed. Then that capacitor is switched out. It's not unusual in a number of areas to find that the torque needed to do that in a reasonable time or even at all is more than the actual running torque.

One of my favourite places to look is ebay new other. All sorts crop up. There appears to be some pure capacitor run motors on there at the moment but going on the one I used they don't arf get hot what ever load is on it.

John

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They use iso 30 or w20 fittings. Min feed 12mm per min - couldn't help looking. That may be with the motor in low speed mode.

Personally I would rather find the right Thiel with it's bits an pieces. No space for one though. It's really unusual for me rate German machinery highly but that one can be really interesting but a pain to set up.

John

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The power you need depends one what speed you are going to run the lathe at. On some lathes that increase the speed to say 5,000rpm I hp wouldn't be that unusual, 1/2 hp more like the norm even up to 10,000 rpm on small lathes such as a Pultra.

You don't say where you are but there are a couple of multi listings on ebay in the uk. One goes down to 120w the other 180w ( 1/4 hp ). Failing that you should be able to get what you want from a motor supplier. If it's capacitor run in my experience they tend to run rather hot what ever the load. Capacitor start and run helps with that but I used a capacitor run once for some time and other than initial worry it didn't cause any problems at all. They can have problems spinning up heavy loads but in practice I would say that's unlikely on very small lathes.

It's worth mentioning that belts slip so tighten them until they will take the size of cut etc that you need and then a bit more.

John

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Curious - has anybody got something against hobs ? One cutter does all.

Actually there is some on in the Ukraine on ebay selling a 0.8M hob for around £32. I bought another size off him some months ago. No problems but I haven't used it yet. It's brand new razor sharp and came in a very neat plastic case. Russian. Tungsten loaded HSS too - and covered with bear fat. That's what they seem to use for protecting microscopes - doubt if it is but it's hard to get off.

I bought another one of ARC for if I need to cut a change wheel for my lathe - they are now on clearance which suggests no one is buying them - I hope - rather than being rubbish.

John

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This pdf might be of interest to people. It was produced by Boxford years and years ago originally but lathes are lathes so it could help some.

**LINK**

The section on tools might be of interest. Pretty ancient wisdom. It even includes some info on the mysterious dark art of fine turning - tool above centre. Ideally this needs a lathe in pretty good order but the results can come as a shock on many materials. It's more of a finishing technique really and can be used more extremely than shown. This area also explains why there are these strange tool bit holders about that hold the tool bit at an angle, also lantern type tool posts with a boat that rocks at the bottom.

The only thing really missing is what the various tool bit angles do. The main one in that area is the side rake into the cut. This tends to hold the tool away from the work and prevent it from pulling in all by itself. If lots of material needs removing on low powered machines it can be increased dramatically to reduce the cutting forces. Best done in steps as it may pull in at some point. Top rake away from the cut can also be increased.

They generally show a toolmakers universal tool bit - V shaped end. Used because it can face, turn, machine shoulders and also cut in the wrong direction even though the rake will be negative.

Periodically I look at my qctp and shake my head. I could use this older method and keep a large array of cutting shapes in a tobacco tin and just use the qctp when it's needed. When - parting off but I might not have enough height available for the tool bit holders I can find.

John

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There are some much cheaper hobs about now. It might be worth looking around. ARC do a few but not this one.

Most of the cheap new ones are MOD. I managed to buy a Russian one very cheaply recently but most are from China. I asked them via ebay if they did any for timing belt pulleys - no was the answer but they may be able to obtain DP. It might be worth asking.

John

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The should be an option to drop out on all mail shots. I just use that. It even worked on ebay once I found out how to do it.

I rely on filtering emails to various folders. One filter I use is if the from is in my address book. If it is it goes to my inbox. That won't suite many people as it means restricting what goes in it. Actually nothing else gets into my inbox. Ebay emails are filtered into an ebay folder. Paypal another. I tend to keep the paypal ones for a long time. Periodically I clean out the ebay ones, some I block select and delete as soon as they arrive without even reading them. Anything else goes into a folder that I call MayBeTrash. It's easy to scan those for who they are from and react accordingly. Sometime an email arrives that I want to keep for some reason, say account details, forums, shops etc. I manually move these to a separate folder. Works for me. If I'm away for a week I might come back to 150 plus unread emails. It just takes a couple of mins to deal with them.

I use separate email addresses for different things all via my ISP. Near 100% one that is an easy target for spammers. That's not too bad these days because they block spammers pretty quickly. In fact it's rare to get one on it now probably because most use something more complicated these days. Another trick some people use to filter out things they probably wont want to read is to play with the name field in the email address. Add an initial etc. I sometimes add my surname, mostly I don't.

One thing I have noticed a number of times is when I communicate with a private individual for the first time. It's not that unusual to start receiving spam. I usually tell them but it generally drops off quickly. I used to bounce ones that came with a virus from these sources. One guy sent me a message telling me not to send him my viruses - it came from him.

I also have my email set up for plain text. Actually I never send html. The reason I also receive set to plain text is that it then takes 2 clocks to fully decode html. The 1st one decodes it so that it can be read. The 2nd one allows it to load external references - that's the one that allows senders to see that it's been read. Ok in some cases and not a good idea in others.

John

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Sounds like your cross slide is way too loose to me. This might be due to uneven wear. If so it will be difficult to do anything about it.

John

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I'm not sure what arrangement you have but on a boxford the tumbler reverse runs onto a gear on the stud. The 1st screw cutting gear fits on the same stud. These will have been set so that the gears mesh on their PCD so can give an idea of how much rotational play there should be. On the boxford I don't think that the spindle gear to tumbler is a reliable gauge. It's machined into the spindle. It might be on others. The tumblers are tufnol anyway so tend to be quiet.

The usual problem I have is meshing the gear on the banjo with the one on the stud.

John

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It's not easy to get change wheels to run quietly and I suspect this is your problem. Can't pass any comment on a paper test - what thickness paper etc. What I do myself is adjust for a little angular play. They mustn't be too tight or too loose. There has to be some clearance.

John

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The easiest source for dilute HCL is cement cleaner. If the item is greasy a pre treatment with an alkaline even washing soda followed by a wash and dry would probably help. HCL removes rust and leaves metals grey. It rusts pretty quickly then. I tried it on a reamer once. No change in size I could measure and it was still sharp.

yes - "modern" things in the directions outlined are a bit strange. People are inclined to want specific instructions on all sorts of things. This seems to discourage thought and lead to an inability to think for themselves and maybe a lack of confidence as well in some areas.

John

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If Brian must have a small light lathe and this one wont work out who ever uses it I would be inclined to point him at Taig or Sherline. I can't comment on Sherline as I have never owned one. I have owned a Taig. I found 2 problems with it. Swarf on the rack feed. They seem to have provided a guard to get round that problem which can be rather irritating. The head bent spoiling the alignment. I should elaborate on that. I needed to repair a pulley so due to access problems had to machine a face of the V in one go with the riser block on. Something like a 3/4" cut with a very very fine hand feed. Later I needed to make a precise 7/8" dia mandrel around 5in long. When I mic'd it up there was 0.003" taper along the length. I didn't have any problem machining it in steps along the length to get to better than + 0 -0.0005". I have heard comments off several people that the initial accuracy of these lathes is spectacular but does drift out with use. The ER16 head may be better but I doubt if it will be as well aligned as the ordinary head. The tailstock is a bit naff but does it's job. The riser block is really made to allow a certain scale of loco wheel to be turned - not for use all of the time on longer work unless people don't mind the problem I had sooner than need be. I bought the basic lathe bits, 3 jaw, 4 jaw, face plate, fixed steady, tool grinding wheel, compound slide and the collets. As I machined the 3 jaw as described on the web I never used the collets. In my case Peatol told me what to do when I asked about holding 3/8 end mills. Looking at the Oz pages on these they now come with a variable speed motor, maybe the Sherline unit. Pass on what that will do. The original 1/4 hp motor and simple mount was more than adequate for the lathe. This is still shown on the UK pages and might still be available. The instructions on what to do with the lathe to set it up initially are on the Oz site. Seems they lap it with VIM and oil, I use a liquid version, CIF and oil. It doesn't take long to do and is only really slightly lapping what is already a good fit.

The simple tool set they do is also ok. The vertical slide can be used to mill down the thickness of carbide cutters if needed - the rather crude way that holds things is a lot better than some vices. Shim is needed to set the tool height. I'd wonder if the QCTP they do will work out with the compound slide fitted.

There was another problem - so much swarf at times that it was hard to see the lathe.

I mounted mine on a wooden bread bin and kept the bits and pieces in it.

Beginners - as the general aspects of the lathe are "OK" I can't really see why any should have any problems at all providing they don't exceed sensible cutting speeds.

I'd guess due to the motor that the Sherline's and the new Taig's aren't as powerful as the earlier Taig. That's either good or bad depending on how it's looked at. Personally I would prefer the power and simplicity of the earlier arrangement. Overload that motor and people will notice a smell. Turn off and let it cool and all is likely to be perfectly ok. I never managed to do that. Screw cutting might make the variable speed option preferable and the Taig still has a number of steps on the pulleys but there are probably designs about on the web for solving the speed problem on the earlier arrangement. Actually I'm not sure if screw cutting is available. Last time I talked to Peatol they were looking at adding it. That's some time ago now and I believe there was some diy designs on the web.

What a mad suggestion - buy a different lathe with a different problem. Why - well it should help people to learn to turn without some stupid problems that I have heard mention of before - more than once. It is pretty easy to hand feed on a Taig as well even though the wheel is rather small. In turning rather than maintaining alignment terms it's a very stable solid machine.

I'm totally disregarding what people might wish to make on it. They need to think through that themselves but actually I suspect that aspect isn't all that different to using any 12in centres lathe. It's just a bit smaller. I wish I hadn't sold mine and am looking at replacing it. That is turning out to be a tough task as I'd rather it was something that retained it's alignment and had screw cutting complete with an indicator.

Maybe there is a sherline owner about who can comment honestly on them. A longer bed is available with them also screw cutting. Variable speed though which would cause me to wonder about low speed torque if motor speed is the only way of achieving it.

John

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