Member postings for Andyf

Maybe these people could help, Pat.

Andy

I've used both hole saws and trepanning tools. The saw was easier, though it creates an annular channel which is hard to keep clear of swarf if done in a vertical miller/drill. The trepanning was done on the faceplate, with sacrificial backing, and the trick seemed to be to get almost there, leaving a thin web of material so the central disc could be broken/levered out while the job was still mounted, to preserve concentricity for further operations.

Andy

Unless you have a very slow back gear, James, doing it under power would need quick reactions. And with only 5mm length to go at, there isn't really room for a wide run-out groove.

Either a hand-crank, or if the work is in the chuck, just use the handle of the chuck key as a tommy bar. After all, you only need about 5 turns for each thread.

If the threads end up against internal and external shoulders, a very narrow run-out groove might help get each of them neat and clean at that end.

Andy

I gather that ladies of negotiable virtue feel the same way, John.

Andy

The non-environmentally friendly solution: a butane refill can for cigarette lighters. Insert delivery tube into SHCS or grubscrew, and press down momentarily on base of can. Sfety specs on, or eyes closed.

Andy

You prove the point about budget machinery, Nobby. A minilathe costs around £500 today. Back in 1970, when £1,000 a year was a living wage, £20 or £25 would buy you what costs £500 now. I expect your Myford cost a great deal more than £30 back then.

All goes to show that you have got the standards that you (or a previous owner) paid for back then!

Andy

Hi Gray,

As you probably know, these minilathes are made by one or other of the Chinese firms Sieg and Real Bull (!). There are detail differences between the two versions, but most parts are interchangeable. I believe the current Sieg machine comes with a plastic spacer but your photos show that you are dealing with a Real Bull, so it may have a metal one.

Andy

PS I have never owned either machine. My knowledge of them stems from my being (for reasons which have always eluded me) a moderator of the Yahoo 7x12 minilathe group, so I see a lot of comments about their idiosyncracies (to put it politely). I agree with your earlier comment that basically they are soundly designed little machines. But, being at the budget end of the market, many examples are let down by poor standards of fit and finish, and things like plastic spacers.

Gray, you said:

"This is just a thought, both the lathes I have recently attended to had their headstock bearing adjustment loose, I mean physically loose, (undone), before you go too far have you checked yours recently, or have you done the taper bearing conversion?"

If you mean end float on the spindle, perhaps this happens on mini-lathes because the spacer tube between the "end float nuts" on the outboard end of the spindle and the bearing in that end of the headstock is often made of plastic. Might it slowly deform, allowing a bit of end float to creep in?

Or perhaps you meant that the locknuts were simply loose on the spindle, and not locked together.

Andy

Thanks for showing, Gray. I bet the owner will be as pleased as punch.

Andy

I managed to bodge a contraption to enable me to mill, on the lathe, 1/3 of a turn of a helix into the face of a disc. The end product was a cam to lift something up as the disc was rotated.

Materials: a QCTP boring bar holder, an old spindle from my Perris lathe, an electric drill and a flexible driveshaft for same.

I'm lazy; full story with pics here, on the MadModder forum. No membership needed to view.

Andy

"Perpendicular" usually means the same as vertical, Nobby. But in geometry it means, to quote from my big (20+ volumes) OED, "Of a line or plane: having a direction at right angles to a given line, plane or surface." In my schooldays, when dinosaurs roamed the earth, we were taught how to use compasses to construct one line "perpendicular" to another. Verticality didn't come into it; the paper was flat on the desk.

Thus, I was meaning that the motion of David's cross slide was not perpendicular to his spindle axis, resulting in concave or convex facing cuts.

Andy

No need for the brown trousers, Jason. As I said, I was taking things to the point of absurdity, and perhaps I shouldn't have done.

Making something for a purpose which is entirely unconnected with firearms, but which could by some nefarious person be used as an improvised gun, wouldn't count. There would have to be an intent to make a firearm. I only mentioned the Firearms Act because Bob's model has an obvious connection with firearms, and thus (though a miniature of something much larger) might itself count as a firearm. Ady1 says Bob has that covered, so that's OK.

I speak not as someone opposed to firearms (in the right hands, of course). I own a couple of legal ones myself, though the populace may rest assured that my single shot .22 target rifles weighing 15lbs each are not the weapons of choice for a bank robber or mass murderer.

Andy

Nobby, if the out of perpendicular cross-slide is a manufacturing fault, David can't true up a faceplate. Sort of chicken and egg situation.

Gray, if the owner of the mini-lathe you mention is who I think it is, he emailed me about it before saying that he was lucky enough to have put it in your capable hands. It would be good to see details of how you sorted it out.

Andy

Edited By Andyf on 12/05/2013 20:50:00

Machine Mart seem to do the same range. Though a bit dearer, they might save on shipping if a nearby branch has them in stock.

(another) Andy

David,

Not sure if "my cross slide moves at an angle away from the work" means that facing cuts tend to leave the surface concave or convex (the terms are used loosely, because the shapes involved are really conical) but I had a similar problem and measured the amount of dishing as shown here .

After making the test facing cut, a dial indicator mounted in the toolpost should show no deflection as it is run from the near side of the work to the centre, because it is following the same path as the tool took. But (assuming the facing cut has a bit of concavity/convexity) when the DI is run from the centre to the far side, its reading over that radius of the workpiece will represent double the amount by which its centre is up or down in relation to its circumference.

Dead flat would be perfect, but it is better to be cautious and aim for a bit of concavity rather than convexity. The latter would mean that a faced item would rock when placed on a flat surface, whereas a slighlty concave item wouldn't.

I didn't find this an easy fix....

Andy

It looks like it's going to be a super model.

One slight worry: in the Firearms Act 1968 (as amended) "...the expression “firearm” means a lethal barrelled weapon of any description from which any shot, bullet or other missile can be discharged..."

That's very wide; taking it to the point of absurdity, it might cover a tube which happened to have one end closed off and a small hole through the side, because if you were so minded, you could stuff powder and ball down it and detonate the powder via the hole. The Act doesn't say "commercially available shot, bullet or other missile".

If the model is realistic to the extent that it is not de-activated in any way, maybe you should have a firearms certificate for it. I appreciate that you will have no live ammunition, and no ammo will be commercially available, but the Act says you commit an offence if you manufacture or possess a firearm, whether or not you have ammo to go with it. Indeed, it would not be too difficult to make up miniature shells from items readily available like the contents of fireworks, starting pistol blanks, lead and brass (though doing so would constitute a separate offence).

Andy.

I've been to a few Harrogate shows, and there's no "bring and buy" stall. As I recall, there are only one or two traders selling second-hand gear.

I agree that it would be a popular feature, but (unlike most radio shows) the exhibition is run by a commercial organisation rather than a club or society. So there would be difficulties over manning a bring and buy stall, and paying "The Management" for it..

Andy

As a temporary measure, and if you have a socket set with 12-cornered sockets (or some ring spanners likewise), see if any of them is a close fit. Not ideal, because the angles in the sockets/spanners are obtuse, so really heaving on them will round over the corners of the square bolt heads.

As an aside, I have a "four way" toolpost with square headed bolts which I use occasionally instead of my QCTP. I found that a plumber's four-armed spanner thingy with a different socket on the end of each arm has a square socket which is a perfect fit.

Andy

Interesting how often Radio 4 has cropped up in the preceding responses. I wonder if the BBC knows that there may be a correlation between the R4 demographic and men in their workshops.

Bound to catch her out, John Kennedy 1. But her paramour's a heel, so it will be no good her running to him for solace.

I'm enjoying Samuel Pepys's diaries this week: 15 minute doses at the end of Women's Hour, repeated at 10.45pm. He really was a bit of a Jack the Lad.

Andy

I think it likely that more MEW than ME readers tend to post here. Someone with the experience and tooling to undertake many of the projects offered in ME is less likely to ask for advice. I'm not trying to categorise all MEW readers as beginners or inexperienced, but I imagine that a good proportion of them are nearer the foot than the top of the learning curve. That is certainly true of me.

Andy