Member postings for Bob Mc

Hi John...

I too had an old Atlas lathe which was in a poor condition and I thought it would be a shame to scrap it, I used some of the parts to re-furbish my own Atlas lathe and decided to make a grinder out of what was left, somewhat along the lines of the Quorn.... I also had a load of bits I collected over the years the main item of interest was part of a height measuring gauge with a nice spiral groove very similar to the Quorn pillar....It had to done!

I cut the lathe bed in half.. which is a considerably sized lump and does need all the safety gear for cutting with an angle grinder as the wheel can easily get stuck and give a nasty kick back, I can't say it is aesthetically pleasing to look at as a Quorn and I am in the process of finding a better motor and drive belt, this I must add is still in an 'experimental' stage and I also need to make a wheel guard as yet ... however trial runs with a much underpowered motor have given good results with mills and drill sharpening, some of the jigs I use are shown on the baseboard...nb... the handle for the cross slide is what you think it is but I had a job explaining why there was a pair of mole grips on the bog handle..!

Anyway a picture explains more than words..

rgds..Bob.

Hi all....

Another 'for what its worth'...

I used a singer sewing machine motor to power a small filing machine I made using a 2 stroke crankcase ... it has enough power to file an 1/2" piece of mild steel but I wouldn't like to try it on anything thicker, after saying that, the poor thing has to move a piston up and down and blow out any air in the cylinder as well..!

Bob Mc.

I had a go at making the Universal Screw Mod Fixture in latest issue of MEW 251.

This is my rendition of John Ashtons design which I desperately needed for reducing diameters & lengths of small screws for an 00 gauge rolling road I am about to make. ... Thanks John for your article; not only is the fixture usefull for small screw holding but I found that it helps when holding bushes which need to be cut to precise lengths.. I hope John doesn't mind my alterations .. I didn't have any hex bar so I just used some round stock and put a knurl on it..

see photo's of screw fitted ready for trimming to size and how I use it to hold a nylon bush also for trimming to size.

Thanks Neil...

Michael.... I suppose a portable head mounted version of the scope would be possible... you would have to make sure you didn't whack the missus on the head with it and a strong neck would be advisable.

John... Mirrors can certainly be made, but they need to have very similar focal lengths or you would have 2 images with different magnifications...and probably a headache to go with it...! The FL's have to be longer than the normal for a Newtonian as the optical path is longer...the FL for the binocs is 43inches.

JA.. I too suffer from a similar problem... I take my time is deciding what project to take on and have a good think about it before committing myself to something far too difficult ... its a bit like deciding to get married..

All..... I have microscope eyepieces as they are purchased in pairs which are x5, x10 & x20 ... although I haven't determined what the FL's of these are perhaps someone might know... the x20's seem to give a magnification of around 100.

Due to the differing eyepiece body diameters I have had to make sleeves for them to fit the holders, I have made the main holders out of plumbing fittings, however the very fine thread needed to fit the holders I made on my Arduino controlled screwcutting lathe.

The plumbing fittings already have an internal thread which has a tpi suitable for focusing, however, the thread is a bit sloppy and I made some friction compound using around 6 parts Vaseline to one part plumbers jointing compound... it doesn't seem to have dried out over a 4 month period...so far.

There is a problem when trying to find objects in the sky, and some sort of angle gauge is helpful here, I use the Stellarium program to find the Az and Alt coordinates and with the lowest mag eyepiece in one holder and a higher mag eyepiece in the other it makes it a little easier to get an overall view of the area before homing in on the object and replacing the x5 with the paired eyepiece for binocular vision.

By the way... if you are interested, some members of the Bolton Group of Astronomers have made really nice looking versions, albeit open frame aluminium on small stands, try Googling it.

nb...have booked my tickets to the London Model Engineering Exhibition...anyone else going..?

I have posted 2 pics as below.... rgds....Bob.

Various eyepieces and sleeves and threads to go with them.

Below

No...! I haven't got one eyeball 1 inch bigger than the other..! this is to show that you can use the x5 for finding and then whilst it is fixed on the object move it out of the holder and go over to the x10 or x20 eyepiece.

Thanks John....

Just in case anyone is thinking of using one of these auto gearbox lifters for mounting a scope.... the rams are not really steady enough for a good telescope and have to be modified; sleeves need to be fitted down the ram/housing interface and these are quite thin... about 1mm thick and wrapped around the ram with a gap of about 3/4inch along the length.... I made mine about 6 inches long out of nylon/delrin.

The bottom ram housing is of course filled with hydraulic fluid and you need to wear gloves for this stuff...

The ram bushings are easy enough to remove but the large nut on the bottom housing requires a large spanner ... I made one... see pic..

...Bob..

Below......Large nut

Below.. Large home made spanner..

Below... A look down one of the tubes.

Hi JA.....thanks fizzy.

There are a number of benefits from having a binocular telescope as opposed to a single reflector, the main one being that we are naturally accustomed to using both eyes and it makes observation easier than having to close one eye... in effect I would say it is more comfortable, just try using one eye to read this ... it's not as good is it..?

I find I can see more detail, whether this is because it is more comfortable is debatable or whether it is because of a stereoscopic effect I don't know, there also seems to be an increase in light gathering and the consensus of opinion seems to be that this 2x6inch binocular scope has a similar aperture to an 8inch single reflector.

Other binocular fans have stated that there is an increase in field of view, I don't know how true this is but I must say that those who have a scope of this type are certainly impressed with them.

There are binoscope eyepieces that split the image of a single scope so that there is a way to use both eyes, however I understand that there is a significant loss of light using one of these devices and they ain't cheap!

All in all I would say that for planetary observation and especially lunar observation the binoculars do have an advantage, it seems as if you are actually hovering over the surface ... but whether all the work in manufacturing the thing is worth it is justified.... probably not.... in my case I was given the parts to put together, I would certainly not have entertained making all the optics as well.

There is a problem in that pointing the thing without any instrumentation does pose a problem, and when the desired object is found I find that a slow motion drive is a help, however this must be on a slipping clutch so that the body of the thing can be grabbed at will and manually positioned; I made a simple clutch using magnets.. on the Altitude bearing ....see pic below

Interpupil distance adjuster.

Right hand collimation adjuster... adjustment can be made whilst observing.

Below.. mirror cells showing collimation adjuster gearing.. also shows how the auto gearbox lifter rams are used for Azimuth bearings...very smooth as well.

Hi All...

I seem to have generated some interest with my larger than normal pair of binoculars.

To give a little bit of history for those who may not have seen the thread containing the description; I was given the parts for the binoculars as the original owner had no means of providing a mount suitable stand for the telescope; it was mounted on a simple steel post which although providing a means of adjustment, made viewing any heavenly body near the horizon practically impossible unless you had been trained in yoga.

The telescope is quite heavy....you can't lift it manually like a normal pair of binocs, it is about 48" long and some 28" wide, and so the original owner could not use it.

For those not familiar with these sorts of telescope, being a Newtonian Reflector you have to look down the scope to look up at the sky, which is ok when looking directly down the scope as it is some 4ft off the ground .... but when the heavenly body is horizontally positioned you have to get down to take advantage of it.. ... and so I made a new stand have a look at the pics...

Right....any questions... rgds...Bob...

Below.....Scope on original stand..

Below... Scope on old stand, you can see it is difficult to get to eyepieces when heavenly body is near horizontal position.

Scope on new stand I designed using automobile gearbox lifter.

Eyepiece arrangement which can be completely remove from the tubes for cleaning etc.

Hope it provides some interest....

As promised some more pics of 2x6 inch reflecting binocular scope..

nb.....Sorry I seem to have taken over this thread .... my apologies...

I forgot to mention that collimation of the two mirrors can be done whilst observing, this is a necessity as I have to trundle the scope across rough ground and it gets a good shake up every time..

The pics... rgds....Bob.

Collimation adjustment knob...right tube.

Mirror Cells collimation adjusters.

Inter pupil distance adjuster.

A look down the eyepiece end.

Slipping magnetic clutch

Hi Neil...

The 2x6 inch scope has turned out to be better than expected, I would say its similar in image quality to an 8 inch reflector but with a more comfortable viewing situation.

I had some problem with the original stand because although it was easy to look down into the eyepieces when the scope was pointed in near vertical positions, but when oriented horizontally I had to crouch down to get to the eyepieces which made any observation uncomfortable. So after much searching and deliberation I bought an auto gearbox lifter and altered it .... I can now adjust it eyepiece level to suit the height of the observer and the altitude of whatever is being observed.

The Azimuth bearing is the actual ram support of the unit and is surprisingly smooth, I fitted a manual slow motion drive to the Alt bearing for fine tuning, this is coupled by a magnetic yoke to the OTA's Alt support so that at any time one can 'grab' hold of the tubes and move it about.

Will post some pics ..

rgds....Bob.

Thanks Cloggs...

It is true that I do have more time on my hands nowadays but after 50 or so years of working I need a break!!

Thanks for noticing the workshop is reasonably clean, but if you have ever suffered from the 'gremlins' which hide tools and bits as other members of the model engineering fraternity have mentioned, then the only option is to tidy up and in the process SOME of the stuff will be found!!

By the way there is no future article about the machine, there was however the original article about using Arduino processors for the screwcutting and leadscrew control of the lathe....see MEW issue 235.

I try to keep busy as best I can and on those cold rainy days I could sit in front of the telly and watch Parkinsons adverts for funeral insurance .... you get a free pen you know...just what everyone is in dire need of..!

I have been busy re-making a binocular reflecting telescope as well as fixing up the lathe and doing other things...will post some pics...

all the best rgds Bob.

Thanks Cymro, Michael G...

... I have now fitted a DC treadmill motor to the lathe, so its features are ... forward/reverse spindle, variable spindle speed, screwcutting any thread...and slow to fast leadscrew motion; all these functions available without changing gear wheels or having to listen to metal gear clanking noises.

will post some pics...

rgds...Bob. underneath... lathe now with homemade pulley cover.... the black box on top is for rpm readout...not got round to that yet..!

Fitted to lathe.. a 20tpi inside thread mandrel nut I made using the screwcutting feature.

In response to Cymro..

I don't know if this post should be in 'Screwcutting clutch for Myford's' ... my apologies to Neil Lickfold.

There was a forum discussion about some aspects of using Arduino's for controlling the leadscrew ... see 'Syncing up Arduino's'... the article was in MEW issue 240... this was my own design and was really an overview of what I did to my 70 year old lathe in order to get round the problem of providing a screwcutting facility and motion control of the leadscrew since the back gearing on this lathe did not exist and the original leadscrew was worn out.

In the space and time I had available for the article some of the features were not really covered, such as the fact that there is no encoder as such and the design is probably the most cost effective way of solving the problem when faced with the choice of buying a new lathe or having a go at re-modelling an old lathe.

Since I made the controller quite a few years ago there have been improvements and a re-thinking of the original design as I understand that only one processor is now needed to provide the signals for the leadscrew and headstock motors so that connecting (syncing) the two Arduino's is not needed.

I am not pursuing this re-design as I am very happy with the control unit I have, it works a treat and I have made quite a few threaded items, the only problem I have had is that the headstock stepper driver motor is underpowered somewhat and care needs to be taken to ensure that the cuts are not too heavy and the threading tool is sharp.

The 'different contributor' you mention was probably Chris Gabel who wrote a great article about using the Electronic Leadscrew Groups device (see iss 235 MEW), and I have no doubt that this is a much better system than the one I designed, and as he mentions there is plenty of backup from its vast member base, however this is not a cheap option and I would argue that the cost of applying the system to an old lathe needing refurbishment should be considered against the cost of purchasing a new lathe.

Well I'm happy to answer any questions you may have...

rgds...Bob.

I had worked as a tv engineer for many years and dealt with changing the old black & white and CRT colour tubes, one thing you may not be aware of is that the high voltage used for colour tubes around 25kV charges up the glass dielectric just like a capacitor, and the charged glass slowly releases its charge over quite a long period of time into the 'plates' producing a very high voltage.

The same goes for the black & white tubes but with only about 16kV.

So...when handling the tube, don't put your finger in the little connector hole!!! even if it was months ago that the tv set was used and even if you short the thing out with a couple of screwdrivers from the hole connector to the outer coating of the tube..! it can re-charge itself and give you a nasty reminder that the electric stresses in the glass are still there.

I don't advise smashing the tubes and there is not much inside to use, the colour tubes do have a 'shadow mask' which is like a very fine sieve .... please also be aware that on being smashed a kind of dust seems to be emitted which may be the phosphor from the screen.

..Bob..

Best wishes and hope you get well soon...

Bob..

The binocular telescope was originally made by a member of the Manchester Astronomical Society, it has lain neglected in a garage for some years and the mirrors were in dire need of re-silvering, the inter pupil distance mechanism was also badly made and I re-made it all using perspex. I am told by the company who have done the mirrors that their tests showed that they are identical in focal length and accurate to 1/8th wave...I have been told that the views of the moon are particularly good and seems like you are hovering over the surface...

I will let you know...!

pic of inter pupil mechanism.

Hi Neil & all.....

am at present re-building a 6 inch reflecting binocular telescope... awaiting mirrors coming back from re-silvering.. hope you like pics...

Thanks John A Stewart for sharing your cnc groups ideas which seem very comprehensive, I can't help asking if you know if the Atlas/Craftsman lathes were made in Michigan ...?

Also thanks to Martin for clearing up a question I had about Mach3 for a lathe, and Mr Q for his words of encouragement .

I would agree with Mr Q, that it would be better to see what other designs are in the pipeline before committing yourself to any particular design, at least these days there is something to use as a model, I hope our Editor Neil would give us a hint in the magazines or in the forum as to what sort of solutions others are going to be submitting for publication, and using his editorial skills I have no doubt he could do this without spilling all the beans..!

nb...were you employed in the communications/radio industry..? I can't help but have a smile when I greet you with..... Hi Q..! (refers to inductor quality).

Thanks also to Mr S.O. Duffer for taking the trouble to have a look how Arduino clocking varies, and his program for providing two tones... I have to agree with Mr S.O. Duffer that using Arduino based systems for CNC is probably not the best way to go, however others have produced something which is very impressive, unfortunately the one I looked at on Utube was all in Russian and there were no details of how it was achieved.

rgds...Bob..

Hi all again....

with reference to John Haine's and Martin Connelly's posts, I had a quick look at the Mach3 cnc system and it is very impressive and to be honest is probably the way to go if you have the equipment..... and therein lies the problem..., from what I can ascertain, and I may be completely wrong, but is it not the case that you need a proper cnc lathe with digital encoders and ballscrew drives for Mach3 to be of any use?

Please don't think I am being discourteous to your posts or finding fault, I have been on the receiving end of this sort of response in other forums and it can be very dis-heartening.

Unfortunately my old lathe which is about to have its 70th birthday soon does not have the benefit of these new fangled devices and it would not be economical to try and fit them at this stage in its life, the idea behind using the Arduino system that I have outlined is that it does not require any encoders and will operate with whatever type of leadscrew is installed.

Please correct me if I am wrong, and again I thank you for the interest shown in my article on using the system I described.

rgds..Bob.

Andy...

you are my hero..!! ha ha ha.... lawnmower...!! that's great...

thanks...bob..

Thanks to all for your interest, in defence of my design which was started some 7 or 8 years ago there were not many designs aimed at the particular problem of providing an electronic gearbox to replace change wheels on a lathe at that time.

I have to tell you that in no way was I expecting to publish an article on this, and it was something that I required for my own use exclusively. My knowledge of programming Arduino's at the time was zero, I specifically had to learn about it for this project.

I certainly did not want a full CNC system which the Electronic Leadscrew Group were producing, I needed a simple effective and cheap as possible solution to the problem otherwise it would have been much easier to purchase a lathe with everything ready and working.

I can understand why the idea of syncing two boards seems to be like 'cutting the lawn with scissors!' however at the time the main concerns I had about using 2 separate boards were that, yes, they might drift...especially as they had resonators fitted and were of Chinese origin, to be honest I was not over confident about their quality.

I decided to to do a few simple experiments to ascertain how much they did actually drift, however with no proper measuring equipment the only recourse of action was to program each board with the Blink program set to 500ms periods and see if they stayed in sychronisation, it confirmed my suspicions, after perhaps a minute or so I definitely detected a change in the blinking phase.

I was also concerned as to whether variations in supply voltage and temperature variations would affect these things, and I was also aware that there would be a difference in frequency of the two oscillators and that perhaps as one increased in frequency the other might be going down.

After much deliberation and not wanting the onerous task of wiring up for one resonator I had to make a decision, would I take the risk of perhaps ruining a piece of turned work I had spent much time and effort on for the sake of a few minutes of re-wiring? or just get on with it and at least be sure that if there were any more unknown gremlins lurking in the shadows then this would lay them to rest.

One member has suggested using a computer to derive the signals for the drivers, which is ok but then you need a monitor and a keyboard as well next to your lathe, yes you could use a laptop, which nowadays are much cheaper than when I started, in fact many things have changed over the time since I started building it and I would have perhaps designed differently in light of hindsight.

I hope this explains some the reasons for the design, and I hope it shows that an old lathe can be given a new life with a little bit of effort which has become easier since the introduction of new boards and a better understanding of using the Arduino's

All the best for Christmas..... Bob.