Largechris

Not going too smoothly with the magnetic build plate I brought. 

Now the plate won't home, I realise this is due to the added thickness. The only video I can find is someone putting some new bolts in to lower the optical sensor trigger by 2mm? 

I'm getting confused  

On 25/11/2021 at 11:59, JimFin said:

The big advantage of a magnetic build plate is the ability to remove a completed print as soon as it has completed printing, put a new magnetic plate on and start another print job immediately, rather that have the printer idle while the resin drains off. Great if you are running a production line.

 

If you are not - it simply adds one more layer of complexity to the process by introducing another number of potential issues such as - weight of print exceeding magnetic grip, magnet adhesion to the plate failing, magnetic sheet warping.

 

They are not a magic cure, you still have to get the supports and orientation right regardless. My thought would be to master those issues with the basic plate and add a magnetic one later if you find the need for workflows. 

Ok thanks, I've already clicked on the link to buy a magnetic build plate lol. 

I'm assuming that the idea is to leave the build plate permanently attached and after each print just wipe it off in place to clean it?

Ah yes I can see magnetic build plates would help - in a way I was hoping to avoid buying myriad add ons lol but that would be a handy addition.

Interesting, thanks. This is inside my house so everything at a steady 21 degrees. I can easily try and warm the resin a bit, but over the course of four hours printing (for example) it will cool back down to room temperature anyway?

Looking at the failed print a bit closer, the bit I've highlighted has printed out as a "plane" rather than the 3D cube structure, like it's kind of fallen apart as it was printing maybe?

TBH, I was impressed it worked the first time as the structure is pretty thin and delicate looking. Obviously I will try a few different test projects, so long as I'm not doing anything obviously wrong.

My first impression actually was that there were fewer adjustments (ie nozzle temperature etc.) with resin than filament printing, and hence less to setup wrong. 

Hello, I'm just starting out with 3D printing, on an Anycubic Photon. 

I printed the test file, an open cube shape, successfully, beginners luck, very impressive.

I then recovered the resin through the supplied filters, and the following day tried to do exactly the same print again.... and failed. 

The base worked, was properly attached to the plate, same as before, so I don't think it was a levelling or gapping issue?  I've ended up with a slightly melted cube as per the pictures. 

The only thing I can think of was the timer ran down quicker than I thought so it might have been hanging finished for an hour or two, before I removed the print, would that have caused this?

1 hour ago, spamcan61 said:

IIRC the '12V dc' output from a Duette is just full wave rectified ac so a cheap multimeter is unlikely to provide useful information beyond 'volts / no volts'. A cheap (as in 25 quid) oscilloscope will give a more meaningful display in terms of what voltage is actually being produced. 

That was my guess from what I was reading on my cheapo meter... anyway easy way to resolve this -

Statistically 64% of forum members have a Duette to hand. I'm sure one or two have the requisite tech to get an accurate measurement. Just for interest.

1 hour ago, Chris M said:

I use these relays

https://uk.rs-online.com/web/p/non-latching-relays/1762712/

 

Cheap and small but they come in a tube of 40. These seem to work fine with a 12 volt DC supply to the coil and the CDU power going through the switch part. I must confess I haven't given them a lot of use yet. 

 

I have been using these for over a year to change the polarity of my frogs and rails downstream of my unifrog points. https://uk.rs-online.com/web/p/latching-relays/1762920/  . SO far they have been perfect.

Perfect thanks

7 hours ago, newbryford said:

 

12vDc from a Duette.....

 

More likely 14v or more with lots of background noise with higher peaks than that - hence the 19v from the caps with a 12v supply.

Tried to get a measurement but don’t think my Voltmeter was really upto it if it’s that lumpy, was reading maybe 16V DC and 17.2V AC but would need an oscilloscope or something to prove some numbers.

1 hour ago, Crosland said:

 

That makes no sense  Are you certain its 12V DC input?

What can I say, I have a magic touch with electrics...

Should be 12V DC off the right hand side of a trusty H+M Duette, and 16V AC off the left hand side... I will double check the power supply Voltages tonight....

1 hour ago, RAF96 said:

I have used normal 12v car relays, such as those used for aftermarket spot lights, etc. These were wired so that the output of my DCC accessory decoder fired into the relay coil and the main contacts were used to port the output from my CDU to the solenoids. The pulse from the acc dec was long enough to pull in the relay and fire the CDU.

The problem is you need one relay per solenoid direction, so my 36 relay ‘plank’ was three feet long.

You can get small multi relay modules but you need to research these as not all are suitable for this type of use. E.g. solid state relays (SSRs) normally only operate from AC loads as they need the reverse cycle to reset the internal circuitry. You can get AC-DC SSRs but at greater cost. Mechanical relays handle both but also have their foibles.

Many such modules are designed to work with the hi-lo logic outputs from Arduino or RasPi and can have various voltage relays, so as stated do your homework before ordering up.

Many thanks,

Slightly terrifying... yes in my head I thought one relay per PM coil would sort out the change over problem, but blimey that's so many components to wire up correctly.

(Sometimes I wonder if my blind loyalty to Peco is not helping, and whether using a more complete and engineered turnout solution eg Kato, Rocco etc. , even it costs a lot more,  would save so much faff.....)

5 hours ago, Crosland said:

The effect is dependent upon both the voltage and the capacitance. The difference is that the energy stored in the CDU increases with the square of the voltage whereas it increases linearly with capacitance.

 

Switching from 12V DC to 16V AC (~22V peak when rectified) is almost a doubling of the voltage so almost a squaring of the energy stored in the CDU. The caps should be rated at least 35V to guard against the AC supply being a bit higher when not loaded.

Thanks, tonight I’ve tested on my particular CDU and on 12V DC input I get 19.2V out, and on 16V AC input I get 21.0V out. 
 

I also doubled up the return wire, didn’t make a difference. However after poking around with the meter it seems I have a few shorts on the diode matrix that I need to sort out as I suspect I’m trying to drive more than the intended number of points on each push button switch.

If I do end up with small CDUs for each point I could still do with some recommendations on suitable relays please?

33 minutes ago, NinOz said:

If more capacitance is required why not just wire additional capacitors to your existing CDU.

 

Not an approach I would use to fire 7 with one blow.  I use individual CDUs, one for each solenoid, maybe two at a pinch, via a diode matrix.

I was wondering that, there's a power transistor on the CDU board, so didn't know if other components in the CDU would need uprating.

Individual CDUs sound like an option but you must need relays, which type do you use?

14 minutes ago, Chris M said:

I move up to six point motors via a diode matrix at the same time with absolutely no problem.

Two things I have done:-

1. Arranged the storage sidings into a 3+3 arrangement rather than a ladder of 6. This reduces the number of points that need to be thrown at any one time.

2. I do have two CDUs. I have arranged the wiring so that each CDU only feeds half the points. Both CDUs feed to the cheap push to make switch, this is then split to two diode matrices, one for each half of the points. The feed then goes to the point solenoid and the common return goes to one CDU for half the points and the other CDU for the other half. No problems at all so far.

 

There is another simple solution. Use the diode matrix to activate relays and run the feed from the CDUs through the switch part of the relay. That way it is easy to create two separate circuits.

Yep that makes sense, the bigger CDU is on order anyway so depending on the results of that and using 16V AC, plus the bigger return wire (two minute job), I will price up relays versus another diode matrix, thanks

33 minutes ago, kevinlms said:

A 12 Volt DC input is vastly inferior to 16 Volt AC input for a CDU. 

You can check the voltage at the output of the CDU with your multimeter to confirm the difference. 

 

What voltage rating is the capacitor?

 

The time taken to recharge the CDU is usually not a major issue, but I found that a transistor based one charges up almost instantly, is superior, if you accidentally select the wrong route and want to correct your error.

Ok I will check the CDU output Voltage tonight and see if it varies according to 16V AC input or 12V DC input cheers

11 minutes ago, SamThomas said:

Do you have a common return for the solenoids ?

 

If so & even if your CDU is capable of changing 7 x solenoids at the same time you need to have a common return wire much larger than 0.5mm as it is carrying 7 x times as much current as the individual wires to the point motors.

Yep, a common return, I saw there was already a lively debate on this board about core sizes required for pulsed current with answers varying between size for biggest pulse (21 Amps in my case maybe so at least 2mm wire) and sizing for average current... anyway that's no big deal I will triple the return wire to 3mm.

52 minutes ago, Michael Hodgson said:

Sorry, simple answer is the chances are it won't work. 

 

Your problem isn't inadequacy of the capacitance available to do the job, which is what you are seeking to address by wiring two CDUs in parallel, the problem is that you are trying to move the 7 solenoids wired in parallel.  The trouble with that is that no two solenoids have exactly the same electrical characteristics, so some are drawing more current than others (albeit only briefly).  More importantly, each diode in your matrix is reducing the CDU's output voltage slightly - and you will have more diodes feeding one point in the route than the next one.  So some of the points are given a higher voltage kick than others.  The net result is that some of those solenoids aren't getting enough of a kick, whilst others are getting too much.  

 

I've successfully run both ends of a crossover (ie two points) sometimes three points at once quite happily off a single CDU.  But 7 at the same time is way too many.

 

The recommended approach is one (smaller) CDU per point, and the diode matrix should be triggering those individual CDUs rather than distributing the load of a big single one.

Thanks that's helpful. If I have more smaller CDUs triggered by the diode matrix, then these would be downstream of the matrix, and wouldn't charge up as the route button is a momentary contact?  

(The diode matrix is the DCC concepts one which is setup to have the CDU on the input side)

6 hours ago, kevinlms said:

What is your input voltage and is it AC or DC? What length and what gauge wiring are you using? Those answer are far more relevant.

12V DC or 16V AC input Voltages, I'm not worried about charging time, I get a light telling me the capacitors are charged whichever I use.

Wire lengths are short, less than 0.5m to each turnout as I'm keeping the controls local to the fiddle yard board. 0.5mm wire for each point motor coil connection (there's only 0.5mm coming out of each Peco surface mount motor anyway so that's fixed) and 1mm for the return. 

I’ve been working on a fiddle yard and I’m using a diode matrix for route selection, due to various track layout limitations ideally I’d like to power 7 turnouts (n gauge surface mount motors) at one time. My 4700uF CDU isn’t coping, so I have a 8800uF one on order.

If the 8800 still won’t work can I wire both CDUs in parallel (ie in parallel off the power supply then both feeding into the diode matrix board) or is that going to cause problems? (LED warning lights are in place to alert to the CDU being charged).

Drove past there last summer, be really interesting to see it all restored onto your layout.

On 06/01/2021 at 11:55, kevinlms said:

Email your supplier, see what they recommend?

Usual sort of problem that it was a Christmas present so I don’t want to make trouble over a fairly small niggle if it’s something I can fix myself.

I’ve narrowed it down - the dc model comes with a 6 pin board (not a dcc chip) that is just for the light function (so a bit like jumpers, the only component is a small resistor).

An alternative 6 pin board comes in the box which is for use when, on dc, you want to turn the lighting off for running two sets nose to nose. I’ve installed that and the loco now works properly - although no headlights. 
 

(I wiggled the pins etc it’s not a duff socket connection).

I can’t really see it, but must be a dry joint or degraded resistor on the original board. 
 

I’m 90% happy that It’s back running just debating whether I want to wave a soldering iron over the removed original board, seeing as the set is brand new.

Santa brought me a lovely Kato N gauge duplex TGV (10-1529) which I think is one of the slightly older model designs probably same era as the Eurostar.

It ran perfectly for a couple of days, now it conks out as more power is applied. The lights still work so power is reaching the loco. It will crawl but when I try to accelerate it comes to a stop. It doesn’t reset itself, if I take the power off completely and wait a couple of seconds it will restart, but still won’t accelerate.

It’s not temperature dependent (garage can be cold but it behaves the same warm or cold), and it’s not controller dependent (does exactly the same with an old Duette and  GM walkabout). 
 

My Eurostar isn’t DCC ready so there’s hardly any components inside, just a capacitor, I’m wondering if this TGV Duplex is more complicated, it seems like something in the loco is “tripping out”. There’s no smell of burning or anything like that. I’m reluctant to poke around inside a brand new model, it came from PlazaJapan so returning is going to be a pain, any ideas please?

Santa brought me another French interloper, be rude not to let it stretch it’s legs

A concept that my brother put together for Bedford West station starts to take shape, this is just a rough basic design to test out sight lines and scale. 
There’s a small pedestrian plaza behind leading to what will be a small road with some industrial units.

As mentioned at the start of this topic, I’ve been mainly using the superb Kato stock with a view to eventually utilising the chassis for some UK outline EMUs. When I started using my brand new Graham Farish DMU, I was getting occasional derailments on plain track which I never had with Kato. 
Took a bit of investigation, it can be awfully fiddly working out what’s going wrong in N gauge. Turns out the Graham Farish chassis, although it’s better than my older UK stock, is not as compliant as the Kato chassis, and on the transition curves (leading into reverse curves) the super elevation which I had stretched out over 24 inches (from inner rail high to outer rail high) was too sudden to get all the wheels seated, and the front set was literally running over the top of the rail. Grrrrrrr. 
 

The transition effect I was going for was based on this classic bit of film of the APT, starting at 8’48. The APT prototype takes about 7 seconds to go from fully one way to fully the other, which is a fair bit quicker than a TGV would normally do. 7 seconds at 120mph in N gauge would take 8 or 9 feet on the layout, which isn’t practical, hence the compression:
 

I’ve bitten the bullet and relaid the transition areas, extending the whole S shape to about 36 inches (bear in mind as the curves are 12 foot radius it’s not very obvious in this picture). Around the curve inflexion point I’ve made a longer flat area to give the loco more chance to “settle” and then the actual super elevation is graduated using increasing thicknesses of plasticard up to a prototypical scale 6 inches (1mm) under the outside rail.

Fingers crossed this is sufficient to get all the stock working in the same way, if not then I shall draw a line and stick with the stock that I know works on the mainlines, and everything else will be relegated to the branch.