Member postings for John McNamara

Pressure washers do a great job cleaning up recycled timber, the dirtier the better.
You will be amazed how the dirt and tool damaging grit is blasted away.

Yes the timber will be soaked on the outer skin at least, but the cleaning is so quick it normally dries fairly quickly.
Any nails left in will be much more visible.

There will be some gouging of the surface if you use maximum pressure, try starting at low pressure and work your way up according to the toughness of the dirt.

Regards
John

Hi

You can get a small device to connect two PC's to one printer

Try googling the following (Assuming your printer is a USB device)

passive usb auto printer share

I used a parrallel port version connecting two networks (Via 2 PC's) to a laser printer for years, no problems

Regards
John

Sheradising is not a wet process.

From my previous link......(Wiki)

Sherardizing is a process of galvanization of ferrous metal surfaces, also called vapour galvanising and dry galvanizing. The process is named after the British metallurgist Sherard Osborn Cowper-Coles (son of naval inventorCowper Phipps Coles) who invented and patented the method ca. 1900.^[1][2][3][4] This process involves heating the steel parts up to ca. 500°C in a closed rotating drum that also contains metallic zinc dust and possibly an inert filler, such as sand.^[5] At temperatures above 300°C, zinc evaporates and diffuses into the steel substrate forming diffusion bonded Zn-Fe-phases.

Google

Bouvet door handles France images

This company manufactures a large range steel and cast iron fittings. The sheradised Zinc plate they use is durable. A good example of the process.

Regards
John

Hi

Mechanical zinc coating is sometimes called sheradising.

Google Sheradising
or try the following link

**LINK**

Regards
John

Hi Roger

Rather than making the bearing from a block of plastic, would it be possible to make the block from Aluminium or stainless then fit a say 2mm plastic sleeve. Companies like IGUS actually sell precision plastic dry sliding bearings with an aluminium body. There is a company in the US that makes them too, I cant remember their name! fairly inexpensive. You can also but ready made plastic Teflon or other bearing bushings from most bearing suppliers, even cheaper.

I suspect a large block of plastic will always be inclined to move a bit rather than a thin metal supported insert.

Regards
John

Hi Raymond

One advantage of the tenons is if you ever do get a bad crash or a cutter jam, the spindle will not be marred by the tool holder rotating and scoring the taper bore. It is hard to imagine how this could happen but it sometimes does.

The first thing I do when looking at a machine is to check all the tapers. It is hard to find a tail stock on a secondhand lathe without a scored bore, most likely caused by a taper shank drill.

Regards
John

Edited By John McNamara on 16/02/2016 06:20:26

Hi AlanW

Wayne R Moore's Foundations of mechanical accuracy analyses various Vway angles.
One of the great classics of machine design engineering.

Try this google search 

foundations of mechanical accuracy pdf

​Regards
John

Edited By John McNamara on 15/02/2016 07:17:26

Hi Robin

Steel ?

It may be bronze or patinated brass.

maybe 6 to 8mm x 2mm flat I don't think it is wire. I wonder if it is rivited?

If I were making it I would first do the harder bend along the thin axis of the bar creating the S shapes then the easier spherical bend.

This is quite a process for a one off.
Lots of jigs. and special parts to make.

Regards
John

The trouble with Scotchbrite pads is the embedded abrasive, it is hard and sharp.

Yes It does scratch glass! I know.......

I was involved in a building renovation a while back and an apprentice was given the job of cleaning windows. He cleaned the glass and presto $2000 dollars worth of window glass to be replaced and repainted. We tried diamond pad polishing them but the scratches were too deep.

From memory it was green from the local supermarket.

I have been scared of the stuff ever since.

Regards
John

Re Cleaning

I just purchased some Browne and Sharp straight edges, one was a bit neglected and there was rust on the nicely scraped face, not really a worry as I planned to re scrape it against a known surface plate anyway if need be but it had to be removed pronto.

Before I go on those of delicate disposition may pass over the following notes.

My normal process for removing rust is to start with strong detergent water and sponges rubbing vigorously, at this point no abrasives have been used. This removes the rust mixed with oil and any other loose matter.

Then I dry the object to see what is left.

In the case of the rusty straight edge it removed maybe 50% of the problem.

for the next step the remaining parts of that needed more vigorous treatment were rubbed over with a sponge and a little Ajax powder (No Scotch Bright which contains very sharp abrasive particles, try a piece on a sheet of glass it will be scratched and ruined) I use a sponge because it does not allow the Ajax to bite in. yes it is abrasive also but a lot milder than Scotch bright.

This left maybe 80 % of the face clean.

There were some stubborn spots left. these were treated individually with Ajax and the fingers gently rubbing the spot. and in a couple of cases fine steel wool. Not the heavy industrial stuff.

The result is the straight edge is now clean of rust and you can still see the original scraping marks. and the rusting has been stopped. I have used this process a number of times on second hand tools and it has worked well.

When finished it is important the part is washed with clean water and dried with a cloth and oiled. Don't wait for it to dry or you may get a brown stain. and use light machine oil not CRC RP7 or any of the other similar canned products they do not last for more than a few days and often leave a stain on metal.

The Hercus is a great machine built by a great Australian company I still have the sales brochure for one, At the time it was beyond my means. The rust visible in the photo does not look that bad, fingers crossed. PM me if you would like a photocopy.

It is amazing to see the original paint in pristine condition. that will have to be masked off and covered together with any exposed metal before any cleaning process is contemplated.

Regards
John

Hi John

I actually have a couple of vibrating feed units, they came from a company that made telephones. There were robotic workstations with pick and place units. The parts were fed from a sorter onto long open tracks that presented them the right way up to the pick and place unit.

Each track had a vibrating unit underneath it, The units are quite simple although fairly heavy
Basically just a solenoid made from "E" lamination's and a straight bar of "I" lamination's spaced a few mm away
The Base has the E side of the circuit attached and the vibrating member the I They are joined by flat spring steel flexures. in a parallel motion There is also a simple controller to control the amplitude of the stroke.

The motion imparted to the parts was quite strong. Imagine a Z linkage and imagine the the solenoid applied a force in line with the upper horizontal line while the lower line was fixed to the base The height of the z would change and the line would move slightly forward causing an object on top of it to lift and due to friction between it and the line to move forward. repeated many times a second the parts move quite well. there being little friction in the opposite stroke direction as the line travels down and away from the part (which also has some remaining inertia) there is less force on it.

I guess you would not make one yourself anyway there are many suppliers.

The Pair i Have are destined for a shaker table to cast epoxy composite parts on. They are quite massive and must have been made for large objects.

**LINK**

Regards
John

Hi John

I doubt if polishing will be the answer as the action of the parts sliding will scratch the surface.

Trying to think outside the square??

You mention a spring is it steel? can it be attracted to an electromagnet attached to an air cylinder powered arm that could be programmed to pick the part and then drop it across the gap?

Assuming the pressed together parts are locked together and do not easily come apart could a vacuum system be used to simply suck them up?

Could the part be blown across the gap with compressed air into a wide funnel ?

Regards
John

Yup... Nice find.

If were near my patch I would already be driving.
Cheers
John +2

Hi Merlin

If you can't find one as a spare part?

Elesa have a large range (I have no connection with them)
**LINK**

I would buy one with a larger bore then make the dog clutch with the same mill bored for 16mm inside to fit on the mill the outside being the bore of the handwheel say 22 to 25mm.

Regards

John

Hi John

The green part is behaving in a similar way to the wedging cams in a Sprag clutch. A little friction and the very powerful wedging action takes over.

**LINK**

I can see this problem happening not only with one part but 1.5 parts or more as well. They can press against each other and you have a jam.

Have you considered a spring loaded roller blind type base for your conveyor with guides each side to stop the parts falling off? Ideally the guides should taper wider in the direction of travel to inhibit any wedging action.

It would help if you defined the problem in a little more detail.

Regards
John
 

Edited By John McNamara on 11/02/2016 07:30:30

Hello John Munroe

One possible solution is to straight Knurl the shaft, However for a 6mm shaft maybe that will be difficult as the shaft may bend if a single knurl is used. the clamp type knurling tool with two knurls one pressing form each side may work reducing the side load.

**LINK**

There are many different sizes of knurling wheel. available individually fairly cheaply you can make your own holder simply if you do not have one..

**LINK**

An alternative if you have an indexing head would be to cut the teeth into the shaft, however there will be no increase in shaft diameter you will need to allow and turn down the rest of the shaft. or make a smaller bore in your gear.

Using a knurling tool the teeth are formed no metal is removed this will increase the diameter of the shaft. enabling a press fit. Many of the plastic gears and other bits in laser printers are attached with this method.

The many teeth hold very well giving a very strong grip.
The method also works very well with Aluminium or brass gears.

Regards
John

Edited By John McNamara on 01/02/2016 12:23:13

Gee these bring back memories, I spent the first 50 years of my life in the Furnishings industry.

They are fabric or wallpaper hand blocks, they appear to be Asian, However the Victorians loved Asian design if you purchased them in the UK it is possible they are English.

The V&A may be able to help you determine their origin if you send them a photo or make an appointment to bring them in.

**LINK**

I have a nice copper and wood English one myself I got it from a printer (Warner) in the UK.

**LINK**

Morris and Co....

**LINK**

Oh.... They are usable. Many of the hand block prints done to this day are done with 100 year old blocks, they can be easily repaired if there is a piece damaged or missing. If you have a complete set you are indeed fortunate.
I would happily give them a new home.

Regards
John

Edited By John McNamara on 26/01/2016 02:04:54

Hi Iain

For screw that is going to get a lot of use Cast iron is not the ideal material, it wears away quickly. particularly with a fine thread. I would be inclined to take a different approach and make an insert.

Starting with an M10 or M12 machine screw (or Whitworth thread, if that is all you have to hand) Just axially drill and tap the machine screw for your M6 fine thread, then drill and tap the cast iron to match your chosen bolt.

A high tensile steel bolt would be even better as long as you have a good quality tap to make the M6 fine thread.

The insert can be epoxied or Loctited in place.

You have the option of leaving the rather large hex head or cutting it off leaving a sleeve like the one below, This one has screw slots, although they are not necessary, just use a bolt and nut set the sleeve in place.

The image below was found at a site in China, however making one is trivial and much more satisfying. I would use steel in preference to brass. It will last for a long time.

Regards
John

**LINK**

Power Feed?

Sure if you are doing a batch and can test: for one offs I prefer to hand feed, this enables me to pull back if the sound changes to the growl that often accompanies a dig in.

Regards
John

Hi Dan

Sometimes the workpiece material is tough and maybe sticky creating little streaks as the parting tool rubs against the side of the work, particularly if the groove is deep. This can cause the tool to dig in.

One workaround is to cut in double steps. of say 5mm deep by cutting a second time slightly offset to widen the groove at each step.

My first lathe was a little less rigid than ideal and this method made parting off easier. there is less drag on the side of the parting blade.

In the photo above the work is supported between centres, needed with a long shaft, I prefer leave the last bit for the hacksaw, or just wiggle the piece to break it off (It may leave a small blemish) normally I reface the end anyway so no problem. Cutting right through can cause the work to wedge in when using the tail stock.

Lots of cutting oil will help.

Regards
John