Brimsdown-The last grand project.

Tell us about your layout, where you put it, how you built it, how you operate it.
Philip Hall
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Re: Brimsdown-The last grand project.

Postby Philip Hall » Thu Aug 27, 2020 10:32 pm

Terry, I am a bit nervous about the dust (glad the machine has got a nozzle to connect a vacuum cleaner!), but I know what PCB can do to saw blades. The blade that came with the machine is now completely smooth after not much use, but I did know that it wasn’t a specially hardened blade. I just didn’t expect the original to be blunted quite so quickly.

Philip

Terry Bendall
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Re: Brimsdown-The last grand project.

Postby Terry Bendall » Fri Aug 28, 2020 7:09 am

As well as some sort of extraction a face mask is a good idea. At the moment of course there are difficult to get. There are different grades of face mask and what is needed for this sort of application is a FFP2 grade. In normal times these could be found in places like B&Q, Wicks, Screwfix, Tool Station, Axminster Power Tools, etc. Some of these places may now have some in stock.

Suppliers are required by law to provide product information sheets on their products and any hazards that may be present, probably on request. A supplier such as RS Components that Tony uses would certainly do this but others that we might use may not. I found some helpful information on PCBs at http://www.acculam.com/MSDS-Epoxyglas.pdf

In reality the dust hazard is probably no worse than cutting MDF which has been debated on here before. Hazardous materials have an assigned Workplace Exposure Limit (WEL) which will state the length of time that you should be exposed to the hazard before PPE is required.

Terry Bendall

davebradwell
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Re: Brimsdown-The last grand project.

Postby davebradwell » Fri Aug 28, 2020 8:53 am

I believe it's the particle size that causes concern as it's the same as asbestos. Key sentence in document is that it's not known to be carcinogenic but high levels of dust inhalation can cause lung cancer. I think this is unlikely with occasional modelling but worth bearing in mind. My scant second-hand knowledge of this subject comes from the late '70s when a pcb plant was being set up at work.

Glass fibre pcb certainly wrecks cutting tools and the pcb people soon had to get their own guillotine as they were rapidly wrecking the good one in the workshop. Suggest cutting long strips and chopping up rather than wrecking small part of blade with many short cuts - or keep moving the fence as the total length of cut is the same no matter how you organise it. Surely any guillotine will curl narrow strips although better condition will give less. Solid carbide cutters are standard for the stuff. Is there none of the cheapo pcb available these days? Fire regs will have discouraged alternatives.

DaveB

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Martin Wynne
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Re: Brimsdown-The last grand project.

Postby Martin Wynne » Fri Aug 28, 2020 9:03 am

davebradwell wrote:Is there none of the cheapo pcb available these days?

Plenty of SRBP copper-clad still available:

https://www.rapidonline.com/rvfm-low-co ... oard-32634

and cheaper on ebay.

10 times easier to cut and work than fibreglass, but not suitable for outdoor use. Thousands of layouts built using it back in the day.

Martin.
40+ years developing Templot. And counting ...

Philip Hall
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Re: Brimsdown-The last grand project.

Postby Philip Hall » Fri Aug 28, 2020 10:38 am

This has all been very interesting, and I’m grateful for Terry’s reasonable take on the risk of sawing the stuff. I’m not spending days cutting industrial quantities, just a hundred sleepers from time to time to make a few yards of track and some strips for pointwork. As this is mostly track for the ‘hidden’ storage yards I am economising on sleepers which will help.

I also didn’t realise (thank you, Martin) that the older PCB was still available, although thickness from Rapid doesn’t seem to be consistent, only within a range. For me, I already have the PCB in small sheets and obviously want to use that up, but I don’t actually know what kind it is. I suspect it’s fibreglass because of what it did to the first saw blade I had. It also seems that it can have a detrimental effect on guillotine blades!

Philip

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Martin Wynne
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Re: Brimsdown-The last grand project.

Postby Martin Wynne » Fri Aug 28, 2020 11:11 am

Philip Hall wrote:but I don’t actually know what kind it is

Hi Philip,

Fibreglass is often double-sided copper-clad. SRBP is usually singe-sided copper-clad.

Fibreglass tends to be white-ish, and translucent if you remove an area of copper and hold it to the light. SRBP is a yellow/brownish colour.

cheers,

Martin.
40+ years developing Templot. And counting ...

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Fri Aug 28, 2020 11:28 am

Philip Hall wrote:I also didn’t realise (thank you, Martin) that the older PCB was still available, although thickness from Rapid doesn’t seem to be consistent, only within a range. For me, I already have the PCB in small sheets and obviously want to use that up, but I don’t actually know what kind it is. I suspect it’s fiberglass because of what it did to the first saw blade I had. It also seems that it can have a detrimental effect on guillotine blades!

Philip


Hi Philip.
Generally SRBP has a brownish appearance and sometimes the paper layers can be seen. It generates a particular smell when sawn. Fiberglass has a translucent grey appearance although other colours are available. One reason for buying a PCB shear rather than a guillotine is that I hope the blade is designed to stand up to such use rather longer.
Many years ago when designing and etching one off PCBs the biggest ordeal was drilling the component holes. Even HSS drills didn't last long. Tungsten Carbide drills are offered as an alternative but HAD to be used in a pillar drill as the least side force caused them to snap.
I have previously sawn up PCB into sleeper strip using the reciprocating saw table attachment on by Unimat using short lengths of junior hacksaw blade but the teeth didn't last long and I dread to think what the fiberglass did to the bearing of the saw despite being a sealed ball race.

PS.
One of the most useful features of the RS website is that by scrolling down the screen on an item, additional product information can be found along with downloadable data sheets.
Regards
Tony.

Philip Hall
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Re: Brimsdown-The last grand project.

Postby Philip Hall » Fri Aug 28, 2020 1:21 pm

Have just checked and almost all mine seems to be fibreglass, so I’ll be careful. Thanks for all the advice.

Philip

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Fri Aug 28, 2020 2:56 pm

The proof of the pudding as they: so time to put it to the test.
This the business side of the shear.
DSCF1086.jpg

It has an interesting reverse action compared with a traditional guillotine.
The safety catch is visible to the right and the blade has quite a large radius to the cutting edge.
DSCF1087.jpg

One sheet of PCB laminate. It isn't exactly flat to begin with.
DSCF1084.jpg

Calculation showed that if I made the first cuts across the 300mm width of the sheet, I should get 522 sleepers per sheet against 520 if I cut across the 200mm width. Not that much difference.
So a 34mm strip was marked and carefully lined up with the blade edge before cutting.
The resulting piece was actually flatter than the parent sheet.
DSCF1085.jpg

As an experiment I then marked a 3.3mm piece and cut it.
DSCF1088.jpg

This does exhibit a slight twist, more apparent in the photo than in reality. But this was easily removed by gently untwisting between the fingers.
Having got the bit between my teeth!
DSCF1090.jpg

The squarish piece to the right is the resulting remnant. i.e waste. It will come in useful for something I'm sure.
Most of the tools used are shown in the above picture with the exception of an engineers square used to mark up the smaller pieces in the remnant strip.
I used the scalpel to scribe the copper side of the PCB as this produces a very fine line and one can feel this with the tip of the blade and use it as a register for the small rule I used for measuring. The long rule was used as a straight edge with the scalpel blade for the 300mm cuts.
The shear produces a very clean cut with little physical effort and produces a satisfying sound as it cuts the PCB.
Incidentally it is made by Inox of Germany.
It does not have a built in depth stop, so I shall have to fabricate something to enable me to consistently cut sleepers to width. I already have a couple of ideas.
Hope this helps.
Regards
Tony.
Last edited by Tony Wilkins on Fri Aug 28, 2020 3:33 pm, edited 3 times in total.

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Martin Wynne
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Re: Brimsdown-The last grand project.

Postby Martin Wynne » Fri Aug 28, 2020 3:08 pm

+1
40+ years developing Templot. And counting ...

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Mon Aug 31, 2020 3:43 pm

I realise this is outside many peoples comfort zone, but further progress on the electrical front.
To go with the picture I posted of the first indicator display board, I have now build and tested, as best I can, the relay control card that partners it.
DSCF1091.jpg

The reverse side.
DSCF1092.jpg


The correct operation of my storage yard requires only one road to be selected at any one time. Using traditional toggle switches relies on the operator returning the switches to off after each move. Not a given. So I decided a system that did this automatically was required.
The plan is to have a push button switch (non latching) for each road in the storage fan. Pressing the switch energises the appropriate relay for that road, 1 to 10, which then latches through one of its own contacts. This will throw the point motor for that road. When a different road is selected, the 555 IC circuit in the bottom right corner, generates a reset pulse for relay 11, which breaks the return circuit for any of the relays 1 to 10 and restores their respective point motors to the default setting.
Regards
Tony.

Terry Bendall
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Re: Brimsdown-The last grand project.

Postby Terry Bendall » Wed Sep 02, 2020 7:41 am

Tony Wilkins wrote:I realise this is outside many peoples comfort zone,


Yes it probably is Tony although my limited, and these days rather out of date, electrical knowledge means I can understand what the circuit will achieve. What it is thought is a neat solution to a particular problem although not many of us will need that sort of capability.

Terry Bendall

DavidM
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Re: Brimsdown-The last grand project.

Postby DavidM » Wed Sep 02, 2020 7:09 pm

Do you have a circuit diagram for your relay card Tony?

David Murrell

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grovenor-2685
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Re: Brimsdown-The last grand project.

Postby grovenor-2685 » Wed Sep 02, 2020 8:25 pm

Regards
Keith
Grovenor Sidings

DavidM
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Re: Brimsdown-The last grand project.

Postby DavidM » Wed Sep 02, 2020 10:25 pm

Thanks Keith, that does seem extremely good value.
I was interested in the implementation of the 555 timer circuit and reset function via relay 11.

Regards,
David

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Thu Sep 03, 2020 12:26 pm

Thanks for posting that Keith. They are ridiculously cheap, way less than the value of the components. They would certainly do the switching but would still need some control circuitry.

As requested David here is the circuit diagram.
Relay card Din.PNG

If you click on the picture once or twice you should be able to enlarge it. It should also be possible to down load it should you wish. Right click the mouse.
Relays 1-10 along the top use one contact to hold or latch the relay and feed into a common rail to ground via the normally closed contact of relay 11.
The second contacts shown below control the points via their local relays.
Each relay is controlled by one pole of a Double Pole Double Throw push button momentary action switch.
The second poles are linked to trigger the 555 timer circuit, which is wired as a bog standard reset timer or mono stable circuit.
The output pulse generated pulses relay 11, which momentarily opens the contact thus breaking any latching contact circuit and resets any relays other than that currently held in by the selected push button. The length of the reset pulse needs to be shorter than the time the push button is held down and is determined by the ratio of R14 and C4. The right most switch D0in resets everything back to the normal road.
I started with this relay card because believe it or not it is actually the simplest of the four as any road is selected by changing only one point motor at a time. The other three require multiple points to be switched together for some roads and that all adds to the complexity.
You did ask.
Regards
Tony.

DavidM
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Re: Brimsdown-The last grand project.

Postby DavidM » Thu Sep 03, 2020 3:59 pm

Thanks very much Tony, much appreciated. As usual for this thread, an elegant solution!
I didn’t realise you were using a DPDT momentary to initiate the 555 reset but all now makes sense. Having the component values for the control circuit is very helpful.

Regards,
David

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Wed Sep 09, 2020 9:37 pm

Although not strictly railway modelling, electrics are part and parcel of the hobby. Having build the first relay card I decided to concentrate on building the remainder of the four relay cards needed for the storage yard control panel. There are four separate fans of turnouts altogether, two for each half of the yard. Down in, Down out, Up in and Up out. however, just to add to the fun, although they are very similar, they are all different due to the layout of the turnouts in each fan. That meant individual drawings needed to be prepared for each circuit board as I needed to make sure I had the design sorted before attempting to wire anything. The beauty of designing things on screen is the ability to modify an existing drawing rather than starting from scratch. Yesterday afternoon I took this picture to post having successfully tested the third one.
DSCF1094.jpg

Today I completed the fourth.
DSCF1095.jpg

Did they all work first go?
What do you think? One of the problems with strip board is the many links needed and particularly cutting all the track breaks required. Some work can be saved by careful design but despite working methodically with much checking invariably one misses something or more likely several somethings. However, they now all function as intended, but I do wonder what won't work when I finally connect everything together.
There remain three more display cards to make, but that may have to wait a while as I need to make the physical panel first and test out a few things.
Regards
Tony.

Terry Bendall
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Re: Brimsdown-The last grand project.

Postby Terry Bendall » Thu Sep 10, 2020 8:36 am

Tony Wilkins wrote:Post by Tony Wilkins » Wed Sep 09, 2020 10:37 pm

Although not strictly railway modelling, electrics are part and parcel of the hobby


I would agree, although things like radio control mean that there are now alternatives at least for loco control. It is a bit less common these days but there was a time when comments such as "the layout was wired up by a good friend since I don't understand wiring" were often seen in layout descriptions. All good until something goes wrong and the expert is not available - and it will go wrong sometimes.

Tony Wilkins wrote:working methodically with much checking invariably one misses something


Very true. My first introduction to using stripboard was about 36 years ago and I can remember a circuit that did not work in spite of checking so I put it to one side. Next day the person I was working with picked it up and spotted a small whisker of copper where there should have been a complete break in the copper strip and which had been left by the cutter. Complete the break and it worked!

Terry Bendall

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Thu Sep 10, 2020 9:57 pm

Tony Wilkins wrote:I need to make the physical panel first and test out a few things.
Tony.

Well here's a start.
DSCF1097.jpg

The printout is one I made some months ago when I was trying out different designs using a combination of Templot, Photoshop and Paint.
This does give an impression of how the control panel will eventually look.
It is quite big, some 48" by 15", but then it needs to be as Block instruments will be housed either side of the panel.
Regards
Tony.
Last edited by Tony Wilkins on Wed Sep 23, 2020 4:45 pm, edited 1 time in total.

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Mon Sep 14, 2020 9:14 pm

The other reason it needs to be this large is to house all the electrical gubbins I wanted to put in it.
Here is a rough layout.
DSCF1099.jpg

As I don't have all the circuit boards done yet, some have had to have stand ins.
DSCF1100.jpg

I next cut holes in the rear panel for the multi-way connectors.
I also cut out a dummy fascia panel from some spare white faced hardboard so I could position the mounting pillars.
DSCF1101.jpg

This allowed me to decide where I was going to mount the row of tag strips and then wire them up to the connectors.
DSCF1102.jpg

DSCF1103.jpg


Regards
Tony.

Philip Hall
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Re: Brimsdown-The last grand project.

Postby Philip Hall » Wed Sep 23, 2020 12:43 am

A little while ago Tony gave us some details of his PCB shear, and I have now had a chance to try out my Proxxon table saw on the stuff, which I think is fibreglass because it's double sided. I replaced the standard blade, by now heavily blunted and of no use, with the 'special steel' blade which the good folk at Axminster Tools had suggested would be the one for the job. And so it has proved. On the initial cuts, it went through the 1mm sheet almost like thin ply or plastic sheet, with a very clean cut. After about thirty passes though, the cutting was a little more difficult, and I found that the very sharp edges to the blade had been blunted, although interestingly the blade still cut very well, just a bit slower and with more curling of the copper surface. This I removed with a medium six inch file, having found that a scraper was no quicker. It's a messy job but a few at a time and I had a pile of sleeper strips after an hour or two.

I think I shall continue with the slightly worn blade until it really won't cut much anymore. I should add that I had the workshop door (right by the bench) open, had the vacuum cleaner tightly connected to the saw table and was wearing a dust mask. I found that there was very little dust spread around after a session so I think it's been safe. After deburring the strips and a long session though you do tend to smell of PCB! It actually reminds me of the smell you got with the old Paxolin PCB, which is odd because it's fibreglass.

I've put some photographs below to show some of the results:

IMG_9761.JPG

After about 20 cuts.


IMG_9762.JPG

Bottom - initial few cuts, middle - after about 10 cuts, top - after deburring.


IMG_9764.JPG

individual sleepers after about 30 cuts: left - the underside, middle - the top, right - after deburring.


IMG_9766.JPG

The machine and the pile of sleepers I have to clean up.


Although time consuming, I had the PCB in stock and it's saved an awful lot of money. And I can cut just what I need, and at the end of it all I have a useful little table saw!

Philip

Terry Bendall
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Re: Brimsdown-The last grand project.

Postby Terry Bendall » Wed Sep 23, 2020 7:33 am

Philp's last picture shows the saw with the guard in place and even with a small machine like this it is always sensible to use the guard since the blade could make a nasty cut in the fingers. Another safety tip is to use a piece of scrap wood to push through the board being cut, with the end of the wood resting on the strip being cut. This avoids the risk of the cut piece flying about the room if it get trapped between the say blade and the fence. Not surprisingly the aid to cutting is known as a Push Stick

Again not a great problem with this size of work but it is on a large machine.

End of safety lecture.

Terry Bendall

Philip Hall
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Re: Brimsdown-The last grand project.

Postby Philip Hall » Wed Sep 23, 2020 3:41 pm

Terry, the guard on this machine has a little lens in it (possibly slightly magnifying) which shows the point of cutting, so this is in itself an encouragement to leave it in place. The only problem is that it doesn’t go all the way to the table bed when cutting such a thin strip, as the fence gets in the way. I use thick coffee stirrers to push the PCB though and against the fence as well as to hold down it down as the bits get smaller.

Philip

Tony Wilkins
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Re: Brimsdown-The last grand project.

Postby Tony Wilkins » Wed Sep 23, 2020 4:40 pm

Hi Phillip.
That seems to do the job adequately. I guess if blades are not too expensive one could keep a spare or two handy.
The smell will be created by the resin that bonds the glass fibers together, which is generally epoxy based with fiber glass boards.
Not sure what they use for SRBP other than it stands for Synthetic Resin Bonded Paper.
Incidentally, I have discovered that my shear does not work so well on SRBP as it tends to split near the edges, so it is back to the piercing saw for that.
Regards
Tony.


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