Member postings for John McNamara

Hi Alan

A touch of Frost!

Yes its already happened. The third world is getting better at making things. Not sure where the Fourth world will be? Someone has to do the menial work. Japan is a good example of where China is heading. Japan has a population of 127 Million. China 1.3 Billion, we are being run over by a Juggernaut.

Will China maintain Dollar Yuan exchange rate at the currently artificially low ratio? or will it follow post war Japan allowing their exchange rate to rise? right now this is unlikely, business is depressed, they plan five years ahead anyway, they can wait; but for how Long? Not that long I suspect.

Free (Sic) trade has decimated Manufacturing. It would be Ironic if in the end we have to pay the piper. Will our cheap goods stay cheap?

Oh I forgot! We now have to concentrate on Services and High Tech. RIP Manufacturing. Well that's what the Politicians tell us......

Regards
John

Hi NB

If you lived in Australia I would try the following link

He has Rack and pinions too.....

**LINK**

Pretty inexpensive. He stocks in Australia. No connection but have had good service.

Regards
John

Older Clarkson chucks can be quite worn

I have a 2mt version I purchased new and it is accurate. well within about .001"

Also have int40 chucks that came with a machine, they are not accurate the closing nose thread which continues onto the aligning surface that aligns with the chuck body bore is worn, this allows the closing nose to move laterally. In my new chuck the joint is tight.

Also have a second hand but better int40 1'' - 1.25" size collet chuck. this bigger chuck runs out about .002"

Clearly condition is important If there is play between the collet closer and the body alignment will be compromised. There is no taper to bring it back into alignment. The threads help a bit, but not so if they are worn.

My ER40 collet chuck also purchased new is more accurate better than .001" radial at the cutter shank. Being taper to taper wear is compensated.

Regards
John

Posted in error

Edited By John McNamara on 19/10/2015 13:27:18

If you buy material when you need it can be expensive, The trick is to acquire it when you don't. I always have my eye out for material. Of course you risk the usual "you are such a magpie" comments from other members of the family! in my family I am usually asked first how big is it? when announce a good find.

Anyway after a bit of digging around my shop more often than not it is "in stock".......

I Keep an eye out for closing down auctions steel offcuts usually sell for less than the current scrap Iron value, dealers wont pay more because there is nothing in it for them.

Regards
John

Hi

I regard R Buckminster Fuller as one of the great innovative minds of the 20Th century. I have a number of his books. For those that may not know much about him the following link will pave the way to an exciting journey.

**LINK**

Regards
John

Edited By John McNamara on 11/10/2015 02:59:19

Hi John Pace
I sent you a Private Message

Regards
John Mac

Hi NB

How about packing the adjustment gap to the correct height and pinning and epoxying both sides of the broken piece to the main casting. Instead of plain pins you could deep drill, tap and counterbore the holes for a number of small cap screws then epoxy or Loctite the screws in place. I would turn up a temporary plug (well waxed) to keep everything aligned while the epoxy and Loctite cured.

Clearly there is no means of adjustment after solid pinning, If you turned up a nice tapered bore flanged bronze bushing and set that in the hole together with your newly made spindle with a taper to match you would have a better setup than original and it would be hidden from view. I would fill the set screw counterbores with body filler and paint over them.

Regards
John

Edited By John McNamara on 02/10/2015 04:39:07

Hi All

This is in response to the quandary Mr Bandersnatch proposed. Is there enough hours left in the glass.

Large projects and time marches on....

Looking at the pictures, the beautifully designed and produced grinder John Pace has made and is continuing to improve there is no doubt of his passion, and investment in time and mental anguish as the inevitable problems that came up were overcome. A huge effort, also countless hours preparing drawings and just thinking.

Given the benefit of the plans and a proven working design I can imagine how It might be produced. I have not seen the plans but by breaking it down into pre cut and steel sections that are welded and or bolted together a lot of time can be saved by laser cutting. Grinders need to be very rigid and massive to damp out vibration some of the plates will need to be quite thick maybe 20mm, no problem... for a modern laser a walk in the park.

Using pre cut material is the next step up from the castings that many model makers purchase at great expense to make their favourite model. I say step up because the accuracy of modern laser cutting is to within a small fraction of a millimetre requiring far less finish machining. Its not unheard of in model making anyway I notice that a lot of train frames and bogies are laser cut. There was also a recent article in MEW on a company that CNC machines and cuts train parts for sale to model makers. It is inevitable that more and more models will be part constructed by modern methods as used by the train model supplier above it saves precious time that many of us don't have.

Right now I am almost finished the design of a 2400 x 1200 x 200 CNC router/mill although it can be made smaller, Currently there are about 150 3D CAD drawings; at a guess triple that for 2d Plan and elevation drawings. I hate to think of how many design hours over two years that have gone into it however there is a reward at the end, most of the machine will be laser cut panels that fit together. When I send the files to the laser cutter the job will be cut in less than a day and most of that will be setting up time. There will still be a fair amount of fettling the assembly Alignment(Big job), other machining work and electrics. I have set a time budget of three months to finish it. There is not a lot of machining to do. It will cost a bit but no more than plans, castings and components for a steam replica engine and boiler. Although being an MEW long term subscriber I am more interested in tools and machinery.

Should works of this magnitude be published as a series in a magazine, Yes if published in their entirety, and there lies the problem they are a bit big.

I have decided to go the self publish route, keeping the work in one volume. if someone wants to build one they can get going straight away divided into segments it would take years. How to protect the computer CNC files that form part of the design is one question I find quite difficult to answer. This will probably apply to many large projects.

The big question is how large works of this kind can be incorporated into and supported by a magazine? I hope they can because it increases the breadth of readership, hopefully and very importantly attracting younger readers, also the small backyard start up businesses that are trying to set up a small workshop that are cash poor but have a vision.

One thing is certain I cant wait to purchase a copy of the John Pace Grinder Plans

Regards
John Mac

Looking at the photos It will be a rather long article. and there lies the problem for the publisher. The readership is so diverse, some readers build models, some build machines, not counting clocks, motor bikes and vehicles, and dozens of other specific interests.

I am also guessing that this machine is not the only Large project that has placed the publishers between a rock and a hard place.

I wonder if it would be better published separately. It is now possible to order short run editions of books published and bound digitally. High quality colour printing too with a decent cover not just a rough photocopy. Books like this could be ordered off the web or via an order form in the magazine and posted out (A Magazine subscribers discount would be nice).

As a one off maybe not worth the effort but if it could be the start of a regular offer of other quality works. I for one would be happy to add a copy to my library.

In the digital age many authors are now "self publishing" using short run printing. There are many services set up to do it.

Regards
John

That is a really Nice Grinder John Pace. A lot of work went into it. Did you design it in CAD?

I can see the column Appears to be thick wall RHS. I cant quite make out how the slides are configured did you use Profile rail? A few more photos would be appreciated.

The base looks very sturdy is it a weldment?

I admire the workmanship.

Regards
John McNamara

A nice clock!

Gee.... I know I am going to get trampled in here suggesting this but a perfect job for the modern Gas Axe... Also called a laser cutter.

The gears almost all of it frame and all. Simple? No. a large amount of drawing and design work on paper or CAD.

After cutting the nice flattened and rolled features can be done after on the anvil, hot metal is fun. still plenty of lathe work.

For the modest level of accuracy required for a large clock like this high quality 1:1 drawings on paper can be scanned into CAD software and then tidied up. Or just pay a draftsman to enter the completed drawings into a cad program to be sent to the laser cutter. As long as the person is only transcribing and not designing it should not take long.

Scale? My guess is the frame is made from 2 x 1/2 or 2 x 3/8 inch black bar. The only issue I can see is if you want to retain an "Old" look the crisp edges of the laser cut bars would have to be rounded off by linishing or grinding. There are various ways to distress the finish. Or better in my view celebrate the present and leave them crisp and new.

Anyway I guess that is enough heresy for one day.

Regards
John

The link below is a laser cut tower clock I Posted here in 2013

**LINK**

Hi Al

Its been a busy week for me.... Not enough time for design. However I have been thinking about a CNC, or pedal power if you insist, small lathe. How it is driven is up to the builder. the basic design is what matters.

This came to mind, I have a great book "Precision Machine design" written Professor Alexander Slocum who also wrote this free course at MIT where he works. A good foundation (No not lightweight) machine design course that is easy to understand with a minimum of maths.

As bearings are being discussed chapter 10 is on Bearings.

**LINK**

Regards
John

Hi All

Struck gold here...... We are not alone, some impressive work being done.

**LINK**

Also here for mineral cast machines. Something we can do in the home shop.

https://www.google.com.au/search?q=diy+cnc+lathe&biw=1231&bih=695&tbm=isch&tbo=u&source=univ&sa=X&ved=0CCYQ7AlqFQoTCNGqp5_K_8cCFYcYpgodMQcEoQ&dpr=1.25#tbm=isch&q=diy+cnc+lathe+granite

Regards
John

Edited By John McNamara on 18/09/2015 04:04:36

Hi
I have always thought that CNC would be the way to go if building a Lathe from scratch. it eliminates change gears, they are not needed with a CNC lathe, CNC allows you to cut any thread metric or imperial.

The lathe in the following link is a superb example.

**LINK**

I like the way the bed is comprised of granite pieces assembled and glued together also the EBay sourced second hand air bearings.
as Michael Gilligan mentioned ball bearing linear slides would also make a good bed. However not the circular type, you need the rectangular type with preload.

**LINK**

If size could be kept down the cost of making on would not be prohibitive. around 100 USD per axis (Motor and driver), even less if you buy bare board kits. Add in the ballscrews and guides surprisingly cheap these days.

**LINK**

&tbm=shop">https://www.google.com.au/search?q=small+cnc+kit&biw=940&bih=550&tbm=shop&source=lnms&sa=X&ved=0CAcQ_AUoAmoVChMIk7zhxLX-xwIVot2mCh2qrQta&dpr=1.55#q=cnc+drive+kit&tbs=vw:l,p_ord&tbm=shop

What centre distance, centre height above the bed and saddle would be ideal? for most model making needs ?

The smaller the better for high precision parts. I think precision is the key. It makes the machine worth building.

Regards
John

Hi John

A true story it starts off topic but I will get to the point ....

When I was in my late teens I helped my uncle restore his 57 Chevrolet, it was his pride and joy having purchased it new.He lived in the country and did a lot of miles in it, it finally needed a full engine recondition and rebore of the big 6 cylinder engine. Being in the country has its advantages.... just down the road was a Alex a first class mechanic of the old school. His workshop was amazing! a couple of lathes included. The engine was removed to be rebored on site. naturally he would do it there on the spot, he had a bolt on boring rig similar to this one: **LINK** I spent a week working on it, it was fun and I learnt a lot. Now getting back to the point as each cylinder was carefully bored and then measured using an inside stick micrometer

It was then I learnt a lesson I have never forgotten. Alex carefully set micrometer in the bore just holding by its own weight. I guess it was set parallel to the crankshaft, He then pressed against the sides of the block and the micrometer dropped out. With hand pressure alone he was able to distort the heavy block enough to release the micrometer.

All materials deflect when subjected to a load.

Regards
John

Hi Mike

There are a couple of subtle differences between the headstock on your lathe and the model I had.

On mine the thrust bearing was visible when you removed the cover. I notice the leaver for tumbler reverse? (or is it to engage the back gear) the setup is different to mine.

It would be interesting to see a photo of the one that has turned up in Wang.

Regards
John

Hi Mike

The thrust bearing on mine was located between the main bearings against the right side of the left spindle bearing. The thrust bearing itself was a large ball thrust bearing from memory about 20mm thick. the main bearings were bronze bushes. you have to keep them well oiled or they will seize.

To remove any play the thrust bearing is tightened against the spindle by a large threaded ring at the left hand end of the spindle that also retained the drive train gear and a collar. you will need a pin spanner. you should find the bearing under the small cover to the left as seen in your photo.

The back gear on mine was under the spindle within the headstock.

It was made from cast Iron as was the bull gear. The gears were badly damaged when I got the lathe. I had to repair teeth on the large back gear and replace the small pinion altogether. I also had to make up a new bull gear from one scrounged from a dealer not easy to find. It was a big job.

If yours are intact without missing teeth you are lucky. Clearly they do not like to be overloaded.

You will probably find there is only a single half nut that engages the leadscrew for screw cutting this is moved down onto the leadscrew by a lever. It too is cast Iron, it is guided by a 3/4 inch (from memory) cast iron spigot. I managed to break that one day while cutting a heavy thread. The fix for that was to bore a slightly smaller hole in the nut body and Loctite in a stepped 3/4 inch mild steel pin to replace the cast iron pin... I still have the pin! saw it the other day in a box....
For Colchester not a good design. It was bound to break one day. Mild steel is better.

The gears on the back of the apron are open. there is no sealed gearbox I would dismantle the apron and clear out the detritus that has accumulated there before greasing everything and reassembling.

One nice feature of the lathe is how easy it is to adjust the headstock alignment. Just loosen (firm not too loose) the 4 bolts that clamp it down (Look up under the headstock between the ways) You can then adjust the spindle axis until it is perfectly parallel to the bed via small jack screws under each end of the headstock.

Regards
john

Edited By John McNamara on 13/09/2015 14:32:10

Hi All

"316 comes off as very fine wire" above.... Yep razor sharp wire. sometimes it will wrap itself around the work. Don't even think of going near it while the lathe is turning. Even when stationary I always use pliers to remove it. It is not brittle quite strong in fact. I got bitten a while back by a wisp of it (and yes the machine was stopped), it caught and dragged on my finger.... Ouch!

Regards
John

Hi All

It you are interested in how Moore tables were made look for Foundations of Mechanical accuracy here:

**LINK**

Worth a browse for other old text's too I found one I have been after for a while.

Regards
John