Member postings for Roger Hart

A month or two back I bought a used C3 type lathe as a cheapish way to get back into some lathe work. This machine had SIEG DRCD readouts on both slides - but not working.

Changed the press buttons, clean up and new batteries and seemed to work OK.

But they seem hard to read and one has gone a bit twitchy. Inside there is a 14 way ribbon cable between the sealed up sensor and the LCD electronics. Does anyone know what the interface is and is it practical to bring this out to an external processor and brighter readout for my poor old eyes.

TBH probably not worth the bother, perhaps a reversion to dials kit from ARC is the way to go for this occasional user. But nice to know if possible to interface to the sensor.

Thanks for comments. I tried my battery electric hedgecutter under the apple trees.. Not enough guts in it to be really usable. I do have a Stihl petrol hedgecutter and that would do the job but I would have to kneel do swing it left and right. You need a bit of overkill for this job.

My strimmer is a cheap unbranded job with a 9.5mm spindle. I could make an adaptor for a circular blade and could fix it so it cannot come off. Still a bit windy of whirling blades.

I do have the bits of a high power YAG laser but the 4 kilowatt lamp and cooling water add to the aggravation factor to say nothing of the fire and blinding risk. Next door farmer won't mind if I do a bit of hoof and horn pruning....

Overall I feel I will be getting out the kneeling pad and Stihl hedge cutter. The tale of a chap cutting his rib cage did come from a two-man team. So harsh words probably. Locally a tree surgeon managed to embed a chainsaw in his chest - but lived to tell the tale. Me, I do use a chainsaw but don't climb trees with it.

Thanks everyone. I will go with the hedgecutter idea, I already have something suitable with an adjustable head and a long handle.

I tend to come up with complicated ideas for simple problems.....

I am a bit windy of a rotary blade on the strimmer - read of some chap who managed to cut through his ribcage with something like that - not fatal but a bit painful I guess.

Fed up swinging a billhook and having the lines break on my weed eater. Contemplating building a robot to tear out brambles under old orchard trees. Think 15cm ruts, 40cm clay ant hills, 1.5cm brambles as well as docks, fences and netting round trees etc.

A full on agricultural mower does the main rows OK but under the trees is a PIA.

Looked at a few designs and they seem like toys but some have the germ of an idea. The choice seems between brute force & ignorance or not quite so much force and a bit of intelligence. Thinking so far some kind of cart with a rotary blade strimmer head on a hydraulic arm with OpenCV on a RPi to tell the difference between my leg and a tree stump.

Has anyone seen or done something similar.

Not exactly a beginner, sold my ML10 a few years ago, now regret it and looking around the market.

My question is can you manually screwcut on a Seig SC3 lathe or are you forced to use the motor drive?

My previous technique was to insert a mandrel handle into the spindle, unhook the motor belt, set the change wheels and start winding. This was crude but very effective and easily controlled. I never really enjoyed the 'drop the handle and hope to pull it up in time' technique.

So, can you do similar on a SC3?

The CV143 tubes were common on the surplus market back in the late 60s. I got one for about 5 bob and hooked it up to an old 9" TV eht power supply. These had a big mains transformer for the eht and a big capacitor to smooth the supply a bit. Handily it had a string of big resistors between eht and ground so easy to tap off about 3 to 4Kv for the tube with a croc clip. But a bit dangerous - that eht supply could kill you as soon as look at you.

The CV143 worked OK but hard to see it as a really useful see-in-the-dark device but it worked well on very dim torch bulbs etc. Very interesting to look up how CV143 tubes were made - very ingenious - they must have been v expensive.

Much later I got hold (cheaply) of an ex military cascade tube. These show up for about £150 to £200 and work off about 4.5 volts to an internal inverter that drives 3 image converter tubes in cascade coupled allegedly by fibre optics. This worked much better with a camera lens at front and a short focus eyepiece at the back. What I found really interesting was to look at the night sky. Not only to see many more stars but also many more small satellites and even meteors. Lent it to someone and never got it back - must have been interesting.

Back then a mate went for a job at Mullard/Philips who made microchannel plate image intensifier tubes for the military etc. Handed a very expensive sample plate to look at he dropped it - and didn't get the job. These tubes could be used as a fast shutter to photograph shells in flight and I was told Mullard had a shed somewhere where shells got shot in one side and out the other for handy snaps.

This reminded me of a Sci Am article - Vol 232 no 4 April 1975 in their Amateur Scientist section. Described a grating ruling engine built by Brian Manning for ruling interferometer gratings.

The screw pitch problem was addressed by a fine pitch screw of sane tpi driven by a small motor/gearbox with a feedback system controlled by a small interferometer looking at the exact number of wavelengths moved at each step. Used a photomultiplier and a homebrew discharge lamp.

All mounted in a big cast iron box to control temperature etc. This chap even evaporation coated in aluminium his own glass plates and made the diamond cutting tool to make the grooves.

Way back on a trip to Vietnam I saw a hand cranked machine with a coarse pitch for putting the rifling in gun barrels. Used what looked like a hand made Archimedean screw rather than the usual gears/leadscrew setup.

I have geared up a lathe leadscrew for a coarse pitch for an optical focuser - hand cranked - otherwise much too lively.

Way way back a local publican got me to oil and meddle with these things. Nasty horrible things to work on.

I do remember the mechanical ones had some little screw-in clamps that blocked particular wheels from settling. So the machine could be fixed not to pay out much. The general strategy was to make the machine generous on say a Thursday night and stingy on Friday etc etc. The electric machines had a rotary switch to do the same job. A lesson in life.

Thanks everyone. Essentially the PC or laptop or Pi than runs the MAME software continually sends the vector buffer to keep the screen refreshed. The data rate is said to be about 1.5 million vectors/second, X and Y each being 12 bit numbers. There appears to be some attempt to sort the vectors into some sort of order to economise on movement time.

I did consider GBRL and G Code but thought that would be too slow and anyway MAME allegedly does the job. An Arduino 'loop' seems ideal. Going straight from LibreCAD to a file > Python > USB seems pretty simple.

At the moment I am at the WD40 stage on getting the front panel and knobs off this old 'scope as well as painting, mowing grass etc etc.

My special thanks to Grindstone Cowboy - I think we should (have) all misspent our youth....

rgrds

BTW, the fpga version does bresenham in hardware but messing with fpga devices is another time consuming exercise.

Thanks all. I downloaded LibreCAD, drew a rectangle, exported as SVG file. Then copied SVG into an editor and it contains the co-ords in a reasonably accessible form. Not tried a dxf file yet but I guess that will do much the same and the Python code will help.

Always been a bit worried by CAD - looks complicated. So thanks all, was easier than expected.

When I finish the painting and all the other jobs I will go back to the display project - unless another project gets in the way.....

rgrds

Thanks everyone for the info so far. The idea for all this came from a couple of websites: trmm.net/MAME/ and trmm.net/V.st/

These are put up by someone called Trammel Hudson who has a long list of interesting projects. The V.st shows the digital to analogue hardware. Essentially USB data in and volts X and Y out. A file of co ordinates is cycled through and sent out to USB to keep the picture refreshed. There is also an fpga version but not sure if that is complete.

Being lazy I have not yet gone into the MAME software. This appears to reproduce old arcade games on modern kit - CRT and LCD displays but has been 'got at' aka patched to output vector sequences. Originally some of these old games ran on real vector displays - so full circle. Essentially atari roms in and vectors out the USB port. There is also a joystick interface that 'looks' like a keyboard.

What I was after was an easy way to generate a file of X and Y coordinates from some sort of CAD system and then roll it through a home brew routine to output the vectors to USB and sit back and admire the view.

All a bit of a waste of time, but what else are hobbies for.

The bad news is that the fairly larger Teensy 4.1 modules are unavailable until 2023 due to the chip shortage.

rgrds

Thinking of turning an old oscilloscope into a vector display - think Space Invaders etc. The electronics are no problem (so far). But I would like to try with a test image or two.

The electronics will take a serial data stream of X and Y and Z (beam on/beam off) data and I could roll my own test data and send it to the electronics.

But it would be nice to have an (easy?) way of producing 2D wireframe images from some free download software - is such software available. I don't really want to spend ages learning how to do a proper tech drawing. Just a squares and a few triangles would do to start with.

The WEB seems full of stuff that seems massively too good for what I want. My starting point is CAD circa 1965.

rgrds

Recently had car instrument panel trouble - random alarms and dial failures. Common problem on older cars of this model. Followed Google and YouTube and re soldered connector pins. Cracked joints on CAN bus pins - very small very hard-to-see cracks.

Now the question is why? vibration maybe, these pins are at the opposite end from the cable clamp - maybe the the cable waggles a bit. The other pins looked OK and Google/YouTube suggest problem is usually these end pins. The bigger question is how to build long term reliable kit, something that could last 2 to 300 years maybe. Looks to be a very difficult problem, most of us are satisfied if the wretched thing works at all let alone lasts over a lifetime.

Not a model but... Kitchen mixer cold tap is ceramic type and drips - but only if water pressure is low due to washing machine or garden hose. Sometimes happens anyway in early morning.

Have fitted new module (brass+ceramic+plastic stuff) but after about 2 months it starts again. Have other ceramic taps in house with no/few problems. Have tried silicone grease - works for about 2 weeks. Ceramic elements do seem slightly scored but there seems some variation in new elements types from you know where - so easier to buy new unit.

Any ideas short of a new mixer (PIA getting old one out).

Top man, respect. Sorry about the finger...

From what I remember from the ATM books, a small amount of warm balsam was applied, the lens put together with no bubbles etc and then put into a brass ring to keep them centred. A small weight applied and left to cool/set. Usually the lens are same size, just a bit of tube - not too tight - is needed.

The tricky bit with a UV setting adhesive is making sure the assembly does not get stuck permanently in the line-up cell, that any smears can be removed and that UV light can get to it so it goes off. A few experiments and a deep ponder.... Thousands of these must be made every day, so it can't be that difficult if only we knew how it was done.

A quick trawl of the web found suitable glues but the stuff on removing/cleanup was a bit iffy - maybe others know more.

Difficult. Just push it out.

A look at some YouTubes - replacing a watch jewel - may help. Essentially the idea is precisely controlled and evenly distributed force - a thou at a time. If I were to try this I think a hard plastic cup with spigot held in lathe chuck and a shaped brass pusher with paper washer in the tailstock. Warm the cell up to expand the brass and soften any cement and apply some force and rotate the cell whilst under force to distribute the push evenly.

I would aim to put most of the force on the outer part of the lens. That looks the tricky bit. Other people may have better ideas. The watchmakers have some fancy expanding tube tools to re-open the burnished cell once you get the lens out.

Experience is directly proportional to the amount of expensive equipment ruined.

I fear you may be right MichaelG. Certainly looks as if front lens is either swaged in or up against a thin collar.

I have had a look at my own small selection and they look as if they come apart from the back - not swaged. But I am not about to test this....

A lot hangs on whether the inside thread and cone is a single piece or two - does the internal threading extend down to or beyond the internal cone. How was it made - one piece or two? William said it does not look to unscrew so will a soak in solvent and a bit of pressure from the front reveal anything other than a cracked lens...?

Otherwise I would be looking for a substitute until the rest of the kit is back in order.

Mmm, wasn't expecting a microscope objective. This article may encourage you.

http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artapr05/dwobjective.html

A human put it together, I am not convinced the lens are swaged in, it is a fairly low power objective and the front lens looks set back in the cell. So should come apart. Otherwise a close enough substitute will only alter the focus a little bit.