Member postings for pgk pgk

My only difference was not usng a telephone diectory.. just printer paper. I'd seen and heard of it being done and assume i just got unlucky. At least it lept towards me and not the window. The window wouldn't have ducked.

Don't be totally put off by the above. Setup your lathe at it's slowest speed without stock or tool - for a finer pitch thread - say m4 fine pitch 0.5mm. At 160 rpm you'ld be cutting 8cm a minute.

Now a minute is a long time. 10 seconds is quite long when on the ball - only 1 and a bit cm. Get used to how fast the carriage travels etc starting well away from the chuck.

For actually having the satsfaction of cutting a thread for real choose a long bar, fine cuts, tail stock support if needed or a large diameter bar and ignore pitch theory for the diameter you chose. Give yourself a good length to drop your thread end into too. In other words set everything up to be favourable.

For a newbie like me there is satisfaction just in cutting a thread.. even if the piece I cut is of no use for any project - just a practice piece. Reflexes and muscle memory apply. As your body gets used to following the rhythm of that carriage moving towards the bar and starting cutting it will get in tune and you can cut a short length of thread. Don't be afraid to stop short of the end of the thread and do the last few turns by hand.

My one try at using the glue and paper method on wood turning ended up with the lump coming adrift and needing a fast hop sideways. that was wth PVA.

The brown foamy glue is supposed to hold metal to stone even but I can;t say i fancy trying that on any decent chunk on a metal lathe.

At the moment it's necessary stuff in greenhouses and seed sowing so shop time will be limited to bad weather.

I've seen videos of that sort of idea.. an ally pallet gripped in 3 or 4 jaw on some bigger machines where swapping chucks is a pain/overhead crane for a quickie job. (or indeed a small check gripped in a large one for tiny work).

Ian,

I'm obviously good at confusng folk with my questions <s>. Yes i could have made up the first part using your technique with adequate sacrifical material. As you say the centralising would be tricky (boring the holes while backplate is on lathe etc).

It would also be possible to make the second part in a similar fashion using oversized material with countersunk bolts to allow for facing off some 6mm to leave the raised portion - something i hadn't thought about until your pic triggered the idea. Although my essential mean-ness hates the idea of creating waste.

As it happens i was planning on making some artistic slots to pretty up the part and reduce weight so such could be used to attach it to a faceplate and then modify them up afterwards....hmmm...

If the concept I'm playing with works but isn't neat enough and i remake it then that could well be second approach.

It happened. There are 4 bolts from the front of the chuck through to the back-plate (which in turn has the camlocks). In the morning when I found the wobble then one (or more) of those 4 bolts was very loose such that the chuck was tilting from it's backplate.

Obviously i dismounted it, took it apart, cleaned and reassembled and cranked those bolts up tight. When I bought lathe the 4-jaw came in a box to be attached to it's backplate and self-evidently i didn't dog those bolts down enough. Threadlock will be considered if it does it again.

Let me try and answer these new questions:

Lathe i a chester crusader delux and 4 mths old.

For the second job, yes a raised boss bored out centrally but not central on the plate - indeed the boss centered by adjusting the jaws.

Bumping referred to the fat that with 2 jasws reversed and 2 normal on the 4-jaw chuck the workpiece was held proud of any support from behind on 2 jaws than meant the palte didnt naturally sit squre to the chuck and took some tapping (or bumping) to get it absolutey level before really dogging down on the jaws. My take on the eliptical hole is that one of my 'digs' twisted the plate or the loosened 4-jaw on it's backplate caused a 'sag'.

There is no question that the 4-jaw had loosened overnight. the amount of wobble when I starte the lathe up was dramatic (handy E switch) and now way would that have passed me by while machining.

I guess if the chuck had slightly loosened and sagged in one plane then it could lead to an ellipse and then sitting there sagging overnight had loosened further/or sagged off the locating boss.

The confusion I caused is probably because i was combining he job i had done with a second phase to be done.

You're correct that i could ave held the first job to a board on faceplate..or even directly on the faceplate since the central through-hole could have been bored through the faceplate central hole. using the 4-jaw did make aligning my marked out centre-pop to lateh centre easier than on a faceplate.

However if wanting to skim the whole surface of the plate on lathe rather than mill: (and for the second part I plan I'm leaving a raised circle of metal to fit in the groove of the first part).. the need is to attach to faceplate (or 4-jaw) such that I can skim off nearly 6mm of the surface to leave the raised circle. That means hold-downs, screws etc cannot be proud of the job.

I've had more time to consider this and i thik my easiest solution is to rough out with endmill (in the mill vice) down to the depth required and leave the raised area and a safety zone then transfer to lathe and tidy up.

That way hold-downs on the edges can be above the surface.

Or indeed the job could be completed in the mill with the boring tower working both inwards for the outer raised circle and boring it out from the middle to leave the raised part.

Like a lot of these things it comes down to a combo of budget and personal circumstances - where you live from the viewppint of haze and light pollution, how fit and eager you are if it's heavier kit and then primary interest..deep sky/planets/moon and indeed photos or not.

I think there's a lot to commend the go-to mounts particularly if trying to view of partial cloud nights when you can get frustrated tracking and losing the object.

When I was playing the only cheap eyepiece cameras were a poor 640x480 res but Id guess were well to cheap over-HD stuff now and the software for stacking and false colouring will be way beter. A long enough cable and you can set things up outside and sit in the warm with a PC and a cuppa .

I must admit that the joys of freezing my buns off at 2am mid winter in a london suburb or driving out to biggin hill to reduce light pollution did detract from the pleasure. And if you're out on beachy head with the kit the suicide patrol still checks on you......

Sorry this is a bit long

Referring back to my question about cutting a groove.. that was a 12mm thick hot rolled plate 115mm x 75mm with the circle centre 30mm from long edge and central with the groove width 8.5mm.

To hold it I used the 4-jaw and reversed two jaws, sat it on the highest jaw flat and ten centred and bumped it until a DTI showed it lying right.

My original idea was to cut the groove then bore a central concentric hole but this wally hadn;t realsied that the one reversed jaw obscured the hole centre from the viewpoint of getting a boring bar right through

I moved it to the mill and swept the groove with a dti to centralise and discovered that the groove is sl elliptical.

Now it turns out that I did have a couple fo digs during the grooving .. so it may have shifted the ite. but it also turns out that whie it ddnlt appear to be a problem at the time - somehow overnight the 4-jaw had loosened on it;s backplate - an obvious vibe i couldn't have missed unless it was way less at the time.

It;s out of round reading 0.05mm less each side of one axis sweep compared to the other.

The questions:

I didn't have any parallels that were a useful 'fit' on the chuck for levelling and i'd have run out of hands trying to centralise the part.. any tricks beyond the setting and bumping I did?

If I put a part like that on a mandrel would the imbalance be too great and if so how to balance it without clamps etc above the working face?

If I used the faceplate should it be skimmed first or just check with a dti?

It using the face plate how best to hold such an item without any holds being above the 12mm thickness?

Now I have two ideas for that.. one would be based on low blocks bolted to the faceplate and then 6 or 8mm grubscrews clamping to the edges or indeed making the plate larger with sacrificial 5/6mm rim that low clamps could hold down onto.

Lastly it occured to me that one could cut the groove on the mill either by making a new tool for the boring tower or a modified flycutter type tool with a vertical cutter specifcially for the radius wanted.to clear the heel of a boring tower tool?

I bought a 150mm refractor years ago .. got it cheaper 'cos one of the focussing trunions had snapped off in transport but I had no problem just focussing with the other. The stand and couter weights for that must be way more than neil's weight.. a heavy devil to shift. And it did detract from the interest by the time it was lugged out, allowed to cool etc. Back then i lived in London and it was the better choice for plaent spotting in poor lighting conditions.

Out here in rural Wales there's zero light pollution but I'm surrounded by 600 foot ridges so my sky sector is more limited - or i have to lug the beast even further away from barns and trees.

I did take soem quite successful pics just with a simple camera set to infinity and lens against lens. But if one wants a whole series of fancy pics to play with with enhancing software then really one needs to consider a motorised tripod and either a high res camera insert or an attachement for a decent camera.

Somewhere in the move i lost the finder scope too and the extra hassles means i havent set it up for a couple of years. I suppose it ought to go on the auction site.

I've had no need to add extra lighting (yet) there's penty of ceiling flouros in my shed and we keep led battery lights about the place in case of rural cut-outs so I can find the genny - could always hang one of those somewhere.

But if soemone wants a potentially neat way of adding lighting .. how about a length or two of angleable coolant nozzle with an led stuck on the end. You can get them all the way up to secuirty floodlight strength these days. I've even got a solar panel powered floodlight on the lower barn which could easiy be modded for the panel on shed roof and the led inside......

It;s done. Took ages.

the smallest HSS tool I had was 3/16 but one problem was the overhang. The QHTP holders.. well when i make some more then I'll make some wider ones than standard cos I'd had to reverse two jaws on the 4-jaw and leave 2 as they were to get my groove centralised. that also meant a lot of time getting it dead centre and parallel to the chuck face and it meant that needed more overhang than i wanted to clear one jaw.

To reduce chatter it was run at 100rpm and painfully slow feeds and plenty oil. Well over an hour (perhaps 2 - I lost track) just cutting after getting it set up and I did get one dig that broke the tool and then caught it again later in the first dig and broke it again - how it goes.

Final nuisance was my last test fit when the bearing slipped from my hold and fell into the groove...I can't get it out. Even with tiny dental picks... too close a fit. And can't take it out of chuck and lose my concentricity. It's only a couple of squid so if necessary I'll destroy it to remove but I finally tapped it right in and now have to figure some protective covering for it while the (many) further operations get done on this plate - jam some rope in?

Edit: Thinking further - once the concentric operation is done this side I'll have a go at putting a couple of holes through from the back which could be useful for bearing replacement and see if i can push it out - assuming i don't wreck it with the drill. I had given the groove a clean out with some scotchbright but not really polished it.

Edited By pgk pgk on 29/03/2015 23:51:20

Nice idea!

It's a groove outside the central hole diameter so opening up to diameter with a boring bar can't be done.

Jason has it right that it is a partial trepanning and his link to three concentric grooves is the right sort of concept with the tool grind he shows being the sort of approach I planned except that I've been avoiding back rake on the tool top after watching vids suggesting it's not that essential on gentle cuts and allows much more resharpening of the tool without having to chop the end off to totally reshape as one wears back on the tip.

I recognised little need for a side rake on the inner groove edge of the tool since the circular face clears but assumed that it could be beneficial when moving inwards to that edge of the groove. a 1/4 tool gives me just under a mm each side for tidying, and I've got one. the reason for thinking 1/4 in was for the increased rigidity of tool and tip for the sideways trimming. perhaps i'll try it and if it causes problems then grind it narrower?

At least i note that everyone dismisses the idea of using the plate as it's own rotary table.

I did trephine an ally plate..3mm thck only and I did that simply by using a 60 threading tool i had and plunging that in and then squaring the edge on the circle I was keeping .. but that;s way softer stuff. I do plan on using the 4-jaw.since it's a rectangular plate. I need a 19mm diameter recess on the other side of the plate aroudn the central hole and plan on boring that width..

This is to seat a thrust bearing in a 12mm hot rolled plate. bearing OD is 47mm ID 30mm and i want to seat it 7mm deep. There will be a central 10mm through hole.

Now the obvious easy way would be a rotary table on the mill but i donlt have one. the two options i see with available gear is to grind a form tool out of 1/4 HSS and plunge cut it gently in the face on lathe then cut sideways. I take it such a tool would be square ended with a nice 10-12deg relief on end and both sides?. The biggest obstacle i see there is the tool corners dulling and a regrind before finishing the base?

the other thought I had was to drill the centre hole then attach to the mill table with a t-nut, washers each side, double nut with enough slack to be able to rotate the plate and mill the groove. I'd have to find some way of clamping scrap each side of the t-nut under the t-nut groove to stop that moving.

Opinions re the best option (or a third) and which is likely to avoid chatter most, please.

Ah, the nostalgic stories..

Now when i was a wee lad working int' factory making black powder for Lord Nelson we used to have 't' wait for London barge to come up estuary with load of barrels from toff's London Privvies. Stinking rich meant sommat back then!

As you lad t'was my job to skim crystals off the barrels rotting urine being good source ammonium nitrate. But since gov'nr 'ere won't let me give't full recipe lets just say that the final mix needed grinding fine.

Safety shoess didnt exist back then but then w couldnt afford clogs either. Factory was by t'river so powered waterwheel. Clever folks built them of threes tone sides with timber river front. that way if a disaster happened then only lads ont' shift and front of factory got blowed to mist. We used to keep a spare factry front round ack so could get going again fast.

When we made our own hooch - it being legal if landowner didn't find still and want his wedge we used to dilute and mix with black powder and fire a sample. 100 proff was when sample burnt clean, didn't go out or blow..

The finer grind gave a faster burn but a lot of lads lost hands doing specials for t' toffs.

I'd wonder how much sanding would be needed to shift the burn marks.. almost worth using them as accent features perhaps with a dark stain? Other options might include iron-on veneers, just paint, being clever enough to paint woodgrain - a bit of a dark art using combs and rag-in any knotting or tile/brickwork all flat surfaces while sanding/staining in the edges to be varnished beading....

Age has shrunk me from just under 6ft8 to 6ft7 and kitchen worktops I find a comfortable height.. but then my arms reach down fine A bit of baking and chopping veggies isn't an issue

I try to avoid bending thesed days.. 'cos straightening back up can be problematic and it's undignified having to crawl to a wall to pull myself back up.

Now my DIY work benches.. yeah.. way higher than most folk could work at. Make it a good height for handsawing and it needs a high stool for sitting at. And then again for most close work I'm used to eyeballing vertically down.

there's far bigger issues.. like the limited choice in cost effective clothes and boots and finding a car that's halfway comfy - why I've had mine for 20years.

But I must admit i don't have a problem with my chester lathe or mill - theres not many times I have to stick my face close to it and i can reach down to the handles standing up and the DRO means I don't have to focus on marks

They're playing at making a profit by whatever means they can get away with.. sadly a model most businesses follow now and multinationals can hide under foreign legislation and finanacial rules and tangle things up in courts.

About the only way to resolve that would be all purchases going through a government portal and being taxed/protected with a need for vendor to try and make a reclaim... but then gov would cock-up and lose millions on another faulty database project and be too scared of upsetting/losing business...

Most dramatic is how cheap postage can be from china to here.. but how expensive it is in reverse. Especially when international agreements mean postal services have to deliver in the country of destination at no further charge or a cut of the original fee. It's why any direct sales from china can beat any outgoing sales from the UK.