Member postings for ChrisLH

I have a budget clamp type knurling tool for use with my Myford S7. It's pretty hopeless due to the excessive clearances in the joints although I have occasionally made a satisactory job. Sorting it out by remaking the joints is one of the many jobs I haven't yet got round to.

Edited By ChrisLH on 10/03/2023 19:56:35

Looks like there are two Corstons. One in Wilts on the A429 near Malmesbury and SOD's one in Somerset.

Andrew,

An incident in my own workshop which may have some relevance to your bent spindle.

I was getting set up to hob some gears using a bought in hob. The hob spindle was very carefully turned between centres and checked for runout. However when the hob was mounted and nutted up, it had a very distinct wobble.Once the hob was removed, the spindle again checked out true. Conclusion, the relevant face of the hob was not perpendicular to its bore. Fortunately, in my case this error was not big enough to bend the shaft permanently and a pair of interposed washers with mating 45 degree faces cured the problem by acting as a crude spherical, self aligning mounting.

I sometimes use a large bore drinking straw (for blowing !).

Can't imagine what it might be but is there a practical application of the Klein bottle ?

I hesitate to ask this as the measuring of the earth and the establishment of the metre was done by people a lot brighter than me. My question is this: does it matter that the standard metre is some proportion of a measurement of the earth ? In my mind, as long as we have a stable standard length that can be accessed for comparison the job is done.

Mine's a rather early S7, SK2142, and it has the lock pin.

We had a series of downlighters fixed in the ceiling and they were prone to turning off in warm weather as the thermostat fitted transformers got a bit too hot. The cheap cure was to shift some of the insulation (single story).

After selling the house, the purchasers tried to take us to court for several £k to have the place rewired because the lighting circuits were only 2 wire instead of the current 3 wire. We pointed out (via a solicitor) that 2 wire was the standard at the time the house was built and that building regs. are not retrospective (can't be can they otherwise every house older than a month or two would be non-compliant). Fortunately buyers shut up after that.

Re installation of LEDs, I can't see how the electrician could complain about that other than to perhaps insist that holders which won't accept Halogen bulbs are fitted.

Apologies, just read the last line. I'm not a professional at least in building regs. so it would be good if others more qualified confirmed (hopefully) the above.

You also need to know Pressure Angle, 14.5 or 20 degrees, to get a satisfactory match.

Are most of you as confused as I am about batteries ?

There are several sorts of non-rechargable batteries but all claim to be longer lasting and higher power so it's hard to tell which to choose. For example, what sort would I need for an alarm clock or a room thermostat. Would it be "Alkaline power, 50% longer lasting" (even short circuited !) or "plus, 100% extra life". And perhaps, judging by the size, for something a little heavier duty, "Pro power, advanced, long lasting energy". Because most of us, unfairly, apply common sense we need to know whether it's long life at low power or short life at high power and it's difficult to tell which from the labelling.

Rechargeable batteries are a much larger minefield. IIRC there are 7 types of rechargeable battey commonly available at the last viewing each with its own energy storage, discharge and recharging characteristics. Although I conscientiously read through the paperwork on purchase of a new device (drill, lawn mower, hedge trimmer, vacuum cleaner, etc.) I'm usually not clear about how I should react to the information. In any case, it would be wonderfull if I could remember it all when it comes to the next recharge. Some need to be totally discharged before recharge for maximum life, others are damaged if allowed to discharge below 50% charge (how do I tell ?), yet others are ruined if left on charge beyond the full charge point, etc.. I'm not into electronics but would it be beyond the current state of technology to provide batteries and chargers with inbuilt provisions for correctly charging these products ?

I'm not expecting solutions but would be interested in comments, particularly from those with the knowledge to deal with my last point.

ega I used Delrin for the pads because I had some. The choice is unlikely to be critical for occasional use. The ali I used is only about 0.090 thick again because I had some and I wasn't planning mamoth cuts. In any case loads are largely up in which direction quite a lot of material is in direct tension leading to small deflections if used gently.

As you say, doesn't have to be a work of art ! I usually get the plastic faced bearings a nice running fit on the job before finally tightening the large clearance bolts at the bottom. Fits my Super 7.

If you are able to identify the hard spot what about cutting it away with an abrasive disc on a Dremel type drill. Never tried it myself though.

I was lucky that some kind soul at an exhibition alerted me to the fact that there were variations. Just having looked at my stock of holders purchased at least 20 years ago they are all marked with a "W" and fit perfectly. But I agree with Martin C., a vee and a flat has always been the way to go with lathe ways so why not with tool holders ? I can't agree with Bazyle, as to my mind, fitting on the inners or the outers of the vees creates part of a near cylindrical surface where positioning would be dependant on mating and angularity of very narrow flats. Quite easy to clamp down in a variety of positions. I await the protests!

I was lucky that some kind soul at an exhibition alerted me to the fact that there were variations. Just having looked at my stock of holders purchased at least 20 years ago they are all marked with a "W" and fit perfectly. But I agree with Martin C., a vee and a flat has always been the way to go with lathe ways so why not with tool holders ? I can't agree with Bazyle, as to my mind, fitting on the inners or the outers of the vees creates part of a near cylindrical surface where positioning would be dependant on mating and angularity of very narrow flats. Quite easy to clamp down in a variety of positions. I await the protests!

A light brake on the shaft ? An easy trial to see if it's worth pursuing would be to use your fingers on a suitable section of exposed shaft. All the usual disclaimers.

Gerry, you have a PM.

Floor insulation board (e.g. Cellotex) is available which is more robust than wall and ceiling board (our builders thought they didn't need to bother which they used for what until I pointed out the imprints of their boot soles in the wall board on the floor). In my workshop I used 50 mm thick insulating board covered with 18 mm flooring chipboard covered with cheap foam backed "lino" (couldn't find it without the foam). The "lino" guarantees a soft landing for dropped items and the latter tend not to roll too far. It has stood up OK except where the wheels of my 5 leg castor chair have made a hole; easily covered with a semi rigid-plastic matt made to protect carpets, etc. from such attacks.

Thanks Michael for the link to the BCA jig borer. Very nice neat machine and because of its small dimensions very rigid I should think. A very limited size of workpiece goes with it of course, probabaly too small for most hobby engineers.

Looking at the larger of my milling machines I often have to resist the temptation (in order to get other things done) to do something about the collumn. It's a channel section casting open at the back but closed by a thin plate held in place by some small screws tapped into the casting. The holes in the plate are clearance. From courses attended many years ago I know (without having done the sums) that the torsional rigity of the collumn about its vertical axis would be increased many times if the casting had been a box section (a la BCA). This obviously would in turn have a major impact on tool/workpiece stiffness in the X direction. So I ask myself does the thin plate have a measurable stiffening effect and would it be worthwhile cooking up something more robust to replace it ?

My feeling re. relative stiffnesses of joint and collumn has been the opposite of Jason's but it would take a lot of work to get at the truth of the matter. This question will undoubtedly have been addressed by makers of professional machines but less likely for our sizes and even less likely to have been published. But I am happy to be proved wrong.

Hello Stuart,

Just to add to my twopen'orth to Oldiron's advice, insulating the the floor as well is not a bad idea if you like warm feet.