Experimental 3D plug track - up to version 244c

[Phil G]

Hi Martin,
2 mm for the plywood and 2 mm for the further protrusion into the cork is perfect.
I will have a crack at the STL latter today.
cheers
Phil,

 

[Phil G]

Hi Martin,
I was talking about loose jaws to be honest, but solid is fine for this experiment would be good to do both anyway, just to see what the full impaction's are.
cheers

Phil,

 

[Martin Wynne]

I have also picked up on James idea of etching the cork as a further means of ensuring the timbers are all in the right place.

@Phil G @James Walters

Well yes, but...

See this topic for more explanation:

https://85a.uk/templot/club/index.php?threads/tip-of-the-day-trackbed-edges.561/

cheers,

Martin.

 

[Phil O]

@Steve_Cornford

Thanks Steve.

They are not really barbs in the sense of having sharp edges. I'm calling them claws or wings. I'm not sure that your idea will work -- surely the claws will break the plywood as you push them through it? Plywood is not going to flex out of the way and spring back behind the claw as the plastic base does. Or maybe it will?

Would you like an STL with some claws 1.6mm below the chair base to try? What is the width of the sockets you are now using?

p.s. If you are selling metal filing jigs you will need to be quick to get a good price. Within days of releasing 241b the world will be awash with FDM filing jigs.

cheers,

Martin.

Hi Gents,

Is it possible to put a slot in the clip to allow it to flex in a little, to allow the claw, barb, wing etc. flex in a little, to avoid breaking the ply. Similar to that used by the motor industry to fit trim panels.

 

[Martin Wynne]

Hi Gents,

Is it possible to put a slot in the clip to allow it to flex in a little, to allow the claw, barb, wing etc. flex in a little, to avoid breaking the ply. Similar to that used by the motor industry to fit trim panels.

@Phil O

Thanks Phil,

I have been wondering about that. I had pretty much rejected it as impractical below about 7mm scale. But maybe, just maybe ... ...

If it could be got working the whole ease of assembly would be transformed, and it would work equally well on plywood.

It would only be possible at the inside (gauge) end of the chair, because the outer end needs the full plug section to accommodate the slot for the loose pin. But that ought to be enough to retain the plug in the socket.

If I get side-tracked into this, it's going to delay 241b even further -- we can't have two separate design changes even before the leaves have fallen off the trees ...

cheers,

Martin.

 

[Steve_Cornford]

Hi Martin,
Please don't get side tracked on account of me.
I have proved, to myself at least, that the press fit chairs work with ply timbers on top of a socketted track bed even with 10" sleepers (stuck down to track bed with Gorilla wood glue whilst aligned with locator plugs).
A point to note that 10" sleepers are only 3.33mm wide and if using default socket width of 2mm that leaves the web alongside the socket only (3.33-2)/2mm wide, 0.66mm which is very fragile.
However the snap fit chairs with a recessed FDM base does seem a good idea.

I intend to have a go with slotted chairs, which could act as their own "locator" plugs as a further experiment with ply sleepers / timbers.

Phil, what is the minimum distance between laser cuts that you can achieve?
the danger is burn through.
Steve

 

[Martin Wynne]

@Phil O

Hi Phil,

You mean something like this?

Now that I've sketched it, I'm going to have to try printing it.

It looks borderline doable. Until I discover that it isn't. There won't be much length available for it on an L1 chair. Of course, there isn't actually a law saying all chairs must have the same plug design.

I may be gone some time ...

Martin.

 

[Phil G]

Well yes, but...

Hi martin,
I don"t disagree, however having looked at all the ballast at and around Heaton Norris junction there is nothing like that amount of local ballast buildup. Its there between the two sets of up and down lines but nothing like thta depth. I guess if you were modelling a country single line then two layers of cork would be required.
on a different topic had a Mars disaster today somehow the build plate tilted mid build which then cause all the chairs to fail and worse a gouge in the FEP, only good news it did not breakthrough the FEP and did not damage the LCD screen from what I can see.
PS I like the split in the plug Idea suggested by Phil O.
Phil,

 

[Phil G]

Hi Matin,
What about a simple vertical slot in the bottom of the plug, and the current taper in the claw, that way as its push on the socket its the slot that would close and then spring back open once its gone home.?
phil

 

[Phil G]

Sorry about your name tying to fast again, Doh

 

[Martin Wynne]

@Phil G

Hi Phil,

No problem about the name -- you can call me anything you like, and lots of folks do.

But there is a problem with your vertical slot -- it would need to be the full length and that massively complicates the slot(s) for the loose pin(s).

Having now sketched Phil's clip-fit idea I'm going to give it a try.

cheers,

Martin.

 

[Phil G]

Hi Martin,
I will bow to your thinking here, one question though if one of the tangs breaks off, will that then not allow to whole chair to come loose?
phil,

 

[Martin Wynne]

Hi Martin,
I will bow to your thinking here, one question though if one of the tangs breaks off, will that then not allow to whole chair to come loose?
phil,

Hi Phil,

Well yes, it would. But it only has to work once, it's not going to spend a lifetime flexing to and fro. And replacement chairs are now ten-a-penny if it breaks when being installed.

I've been very impressed with the toughness of the resin chairs. If you have made some for loose jaws, try flexing the inner jaw on the chair, or the pin on the loose jaw. That's with the Elegoo ABS-Like resin of course.

cheers,

Martin.

 

[Martin Wynne]

.
I've made a start.

But I'm a bit busy for the next few days, so it's not likely to progress very quickly.

cheers,

Martin.

 

[Martin Wynne]

@Phil O

Hi Phil,

This idea has worked out quite well:

The tang is a tiny thing in 4mm/ft scale, but just about enough to work. The empty space behind it is to allow the surplus resin to wash out, leaving room for the tang to flex.

The plug clips into place very easily, with a detectable click. It needs very little force, so no need for a cocktail stick punch or pin hammer -- hand assembly is easy. However, because the tang is offset towards the gauge end of the chair (necessary to clear the slot through the plug for the loose outer jaw), pressure needs to be applied nearer that end to keep the chair level in the socket while pressing it home. The solution is to fix a bit of rail across the end of a suitable handle (or bend the end of some rail), which can then be hooked under the inner jaw and used as a push-stick to press the chair into place.

I'm calling this design clip-fit. The other options are the existing interference press-fit, and snap-fit with a solid tang requiring the FDM socket to flex, rather than the plug. The first two can probably be used with laser-cut plywood sockets, but not snap-fit.

One significant advantage of clip-fit is that it is more tolerant of socket size variations than the other two.

I haven't yet decided which option to make the default. The clip-fit needs some further work on the L1 bridge chairs and the crossing chairs, and a lot more testing.

edit: see later post: https://85a.uk/templot/club/index.php?threads/experimental-plug-track-continued.673/post-7461

cheers,

Martin.

 

[Steve_Cornford]

Hi Martin,
Whilst fiddling with some nickel-silver strip for use as a stretcher bar, I discovered that I had a piece that was the right dimension to insert in a chair slot and use as a pickup & Insertion tool for slotted chairs. I might try soldering a small length of rail across it to make a push in tool. The strip needs to be of smaller dimension than the loose jaw pin so that it doesn't damage the slot.
Or I suppose you could 3d print a holder that a piece of rail slots into to act as the pusher.
Steve

 

[Phil O]

Martin,

Good to know that the idea, has produced a workable solution to the problem.

 

[Martin Wynne]

.
I would welcome some thoughts on how far I should go before releasing the next update 241b. It's now 6 weeks since 241a.

New and working since 241a:

vee rail filing jigs
switch blade back filing jigs
knuckle bend gauge
new options for plug fit in sockets
integration with 3D Builder for mesh fixing
additional brick information on the storage box dialog
start made on redesigning the temporary DXF/STL dialog

Unfinished or unstarted:

switch blade front filing jigs
slab & bracket "A" chairs
rail bending jigs
save custom data
chair indications on printed paper templates/PDF
switch drive (tie-bar/stretcher)

Still somewhere in the distant sunny uplands:

chairing for K-crossings
fishplates and switch anchors
full support for CNC-milled timbering
proper user interface for 3D exports
detailed tutorials and videos

Am I still conducting an experiment? Or have we reached a stage where I can say plug track is now a usable feature of Templot? Already some bits and pieces have appeared in public at the Wells show last week. There is talk of having something on display at Scaleforum next month.

edit: and as I was writing this, Scalefour News 234 dropped through the letterbox with an article about plug track. Also a review by Tony Wilkins of the Finetrax P4 kits.

cheers,

Martin.

 

[Steve_Cornford]

Hi Martin,
still experimental? Probably.
Usable? Most definitely yes.

How much work to add the switch blade front filing jig to accompany the rear one?

Steve

 

[Martin Wynne]

How much work to add the switch blade front filing jig to accompany the rear one?

@Steve_Cornford

Hi Steve,

Difficult to say -- I'm still tinkering with ideas. It needs separate jigs for left and right hand blades, but I'm hoping to combine them in a single jig.

I agree that it would be a bit daft to release an update which did only half of the job, but I can sense folks eager to get their hands on the vee jigs at least.

cheers,

Martin.

 

[Steve_Cornford]

I am also looking forward to giving the clip-fit and snap-fit options a go.
Steve

 

[Paul Boyd]

.
I would welcome some thoughts on how far I should go before releasing the next update 241b. It's now 6 weeks since 241a.

New and working since 241a:

vee rail filing jigs
switch blade back filing jigs
knuckle bend gauge
new options for plug fit in sockets
integration with 3D Builder for mesh fixing
additional brick information on the storage box dialog
start made on redesigning the temporary DXF/STL dialog

Unfinished or unstarted:

switch blade front filing jigs
slab & bracket "A" chairs
rail bending jigs
save custom data
chair indications on printed paper templates/PDF
switch drive (tie-bar/stretcher)

Still somewhere in the distant sunny uplands:

chairing for K-crossings
fishplates and switch anchors
full support for CNC-milled timbering
proper user interface for 3D exports
detailed tutorials and videos

Am I still conducting an experiment? Or have we reached a stage where I can say plug track is now a usable feature of Templot? Already some bits and pieces have appeared in public at the Wells show last week. There is talk of having something on display at Scaleforum next month.

edit: and as I was writing this, Scalefour News 234 dropped through the letterbox with an article about plug track. Also a review by Tony Wilkins of the Finetrax P4 kits.

cheers,

Martin.

Hi Martin,

Whilst tinkering with something entirely unrelated, my mind was wandering! You say this new clip-fit design is more tolerant of socket size - I wonder if, for those of us for whom domestic constraints mean we can’t have a resin printer, we could now use a commercial 3D printing service such as Shapeways for the chairs, and tinker with FDM timbers so that those chairs fit? I have no idea whether Shapeways or any other commercial service could actually print the required level of detail accurately though, in particular clearing slots thoroughly.

Cheers,
Paul

 

[Phil G]

I would welcome some thoughts on how far I should go before releasing the next update 241b. It's now 6 weeks since 241a.

Hi Martin,
I think Steve is about right, front switch blade jigs and slab and bracket AA chairs do make sense to be in 241b.

I can also see what your saying about the clip fit plug concept, however they may or may not work.(I hope it does) So I don't think that is directly connected to 241b. On the clip fit idea I fully understand why you want to pursue this Idea. However if you think about it, there is currently no system on the market commercial or not, that does not need some sort of glue to assemble.

I think from an experimental perspective, your very close to calling plug track a working feature of Templot. All be it maybe a Beta release. with more to follow.
There is an argument for people to get the best out of Plug track, some form of access to at the very least, a resin printer and another means of making the timbers is required. Therefore I would have though, if more people were aware of what it can do, the more likelihood clubs will look at purchasing resin printers, and FDM or laser/CNC options.
cheers
Phil,

 

[Terry Downes]

.
I would welcome some thoughts on how far I should go before releasing the next update 241b. It's now 6 weeks since 241a.

New and working since 241a:

vee rail filing jigs
switch blade back filing jigs
knuckle bend gauge
new options for plug fit in sockets
integration with 3D Builder for mesh fixing
additional brick information on the storage box dialog
start made on redesigning the temporary DXF/STL dialog

Unfinished or unstarted:

switch blade front filing jigs
slab & bracket "A" chairs
rail bending jigs
save custom data
chair indications on printed paper templates/PDF
switch drive (tie-bar/stretcher)

Still somewhere in the distant sunny uplands:

chairing for K-crossings
fishplates and switch anchors
full support for CNC-milled timbering
proper user interface for 3D exports
detailed tutorials and videos

Am I still conducting an experiment? Or have we reached a stage where I can say plug track is now a usable feature of Templot? Already some bits and pieces have appeared in public at the Wells show last week. There is talk of having something on display at Scaleforum next month.

edit: and as I was writing this, Scalefour News 234 dropped through the letterbox with an article about plug track. Also a review by Tony Wilkins of the Finetrax P4 kits.

cheers,

Martin.

Hi Martin, I would suggest releasing now. Why not? The hand full of power users understand that everything is likely to change and enjoy contributing to the development.
Regarding onward priorities, I believe a full suite of chair designs is key to Plug or 3d printed trackwork to truly take off. So, for me chairing for K-crossings is top of the list.

 

[Terry Downes]

Hi Martin,

Whilst tinkering with something entirely unrelated, my mind was wandering! You say this new clip-fit design is more tolerant of socket size - I wonder if, for those of us for whom domestic constraints mean we can’t have a resin printer, we could now use a commercial 3D printing service such as Shapeways for the chairs, and tinker with FDM timbers so that those chairs fit? I have no idea whether Shapeways or any other commercial service could actually print the required level of detail accurately though, in particular clearing slots thoroughly.

Cheers,
Paul

Hi Paul, I'm a semi-retired freelance CAD Design consultant with a Form3 resin printer and a Kobra plus FDM printer. I find that chair/plug/rail fits can vary from one week to the next with exactly the same settings etc. So, small test prints are essential for small accurate/precision components. I have designed many components for customers which I have 3D printed as prototypes and then sent for volume printing via print houses but, the results are always underwhelming and inconsistent. I don't think printing houses will provide a consistent or accurate supply of 3D trackwork. I believe the long term solution will be a network of resin/fdm printer owners/users like myself who will be able to provide a personal service at a reasonable cost specifically for Templot generated stl files etc. I'm willing to provide print items at material + postage costs if you wish.
Regarding your comment about clearing slots yes, I agree, this is a very important process and I was wondering whether Martin would consider changing the square peg of the loose jaw to a round pin? This would enable the holes to be run through with a small drill bit to clear any resin etc. Just a thought...

 

[Steve_Cornford]

Hi Terry,
Having the pins rectangular aids holding them with tweezers in the correct orientation for insertion into the slots.
So far I have not had a problem with blocked slots, but then I do follow Martin's guidance and perform a couple of vigorous dunks in the 1st IPA bath before a 6 minute wash in 2nd tub, and a further 6 minute wash in clean IPA, then a blow through and dry using hair dryer on cold setting before curing.

Steve

 

[Winander]

I prefer wood because it is not plastic. Thin Baltic ply is probably more expensive because most of the thinner sections are made in Russia, at least that's what the internet told me

 

[Steve_Cornford]

Hi Winander,
Martin has provided a clip-fit option to provide for ply timbers, see:-

@Phil O

Hi Phil,

This idea has worked out quite well:

View attachment 6602

View attachment 6601

View attachment 6600

The tang is a tiny thing in 4mm/ft scale, but just about enough to work. The empty space behind it is to allow the surplus resin to wash out, leaving room for the tang to flex.

There are pros and cons, as always.

The plug clips into place very easily, with a detectable click. It needs very little force, so no need for a cocktail stick punch or pin hammer -- hand assembly is easy. However, because the tang is offset towards the gauge end of the chair (necessary to clear the slot through the plug for the loose outer jaw), pressure needs to be applied nearer that end to keep the chair level in the socket while pressing it home. The solution is to fix a bit of rail across the end of a suitable handle (or bend the end of some rail), which can then be hooked under the inner jaw and used as a push-stick to press the chair into place.

With the low assembly force, inevitably the retention force is not so great. It's not difficult to push the chair out from below, or prise it up from above using the blue cutters. But it is plenty firm enough to permit construction, so if it is desired to seal it in place for long-term stability, it can be done using a slow-setting adhesive or sealant, possibly at a later date. My tinlet of old Humbrol paint is the solution, as always.

I'm calling this design clip-fit. The other options are the existing interference press-fit, and snap-fit with a solid tang requiring the FDM socket to flex, rather than the plug. The first two can probably be used with laser-cut plywood sockets, but not snap-fit.

One significant advantage of clip-fit is that it is more tolerant of socket size variations than the other two.

I haven't yet decided which option to make the default. The clip-fit needs some further work on the L1 bridge chairs and the crossing chairs, and a lot more testing.

cheers,

Martin.

Steve

 

[Martin Wynne]

.
Many thanks for the comments and ideas.

I have been tweaking a few settings for the clip-fit plugs:

I beefed up the tangs, and cleared the space behind them to a full through hole right through the plug. This allows proper washing of surplus resin from behind the tangs.

I feared this might weaken the plug too much, but it seems to have had little such effect. The wall between this hole and the loose pin slot is only 0.3mm thick (12 thou) in 4mm scale, but again that doesn't seem to have caused any problems for the loose jaw fitting.

Then I adjusted the dimensions for the undercut in the socket wall to receive these. I found that the tangs were not fully opening, despite there being plenty of clearance in the dimensions. I increased the clearance to make sure.

These changes have made a big difference. These plugs now clip into position quite easily, but are then almost impossible to remove. As I originally hoped and intended. Pushing them out from below now requires very considerable force. Or they can be prised out from above using the blue snips, but the chair is wrecked in the process. Fortunately they cost only ten-a-penny to discard and replace.

So I think I have decided to make this option the default, but the other options remain available if preferred -- for example if a less resilient type of resin is used.

As expected once we get going, lots of hints and tips come to light:

1. I have discovered that a sharp cocktail stick can be pushed firmly into the pin slot while the chair is still on the raft. And then becomes a convenient handle to hold the chair while it is snipped from the raft and placed in its socket. The chair clips into place, and the cocktail stick is then pulled free, without leaving any apparent damage to the pin slot. If it is desired to use some glue on the plug, the cocktail stick would provide the perfect means of holding it while the glue is applied. But I'm happy now that no glue is needed.

2. In the event that a chair needs a little more pressure to seat it home, I found the perfect push stick in the form of a miniature screwdriver which came originally from a christmas cracker.

So a pleasing result after a lot of tinkering with the 3D printers. I think I've earned a boiled egg.

I'm now going to return to the filing jigs. If I can't get the switch blade front jig done within the next few days I shall release 241b without it. But I'm hoping not to have to do that.

Thanks again for your thoughts, especially to Phil for nudging me towards trying flexible tangs.

cheers,

Martin.

 

[Phil G]

So I think I have decided to make this option the default, but the other options remain available if preferred

Hi Martin,
Are you suggesting 241b will have the clip fit option on all chairs on its release? If so well done, that's great progress,
I look forward to getting some clip fit chairs printed, once I get my Mars back up and running, as my FEP is now no good.
Phil,

 

[Martin Wynne]

Are you suggesting 241b will have the clip fit option on all chairs on its release?

@Phil G

Hi Phil,

Sure. But it may not necessarily be the best option on all chairs -- some long plugs may have only a short tang to fit between the loose jaw slots, and might need some glue to create a stable fit. Some chairs might do better with a second tang, but that won't be in 241b, otherwise it never will get released.

However, there won't be an option to mix plug types in the same file. That may come later. If you want to use different types for different chairs it will be necessary to put them in a separate file. Which also has implications for the corresponding timbering files. Snap-fit plugs can fit the same sockets as clip-fit plugs if told to do so with the pin hammer. But not the other way round. As always there are a lot of ifs and buts to sort out before we are done.

Sorry to hear about your FEP damage. Did you get a spare one included with the Mars? I had a similar build plate move when I started with the Mars, fortunately it didn't do any damage. Caused by not realising how tight those levelling screws need to be to resist the print suction forces. Most printers seem to be moving towards the 4 slotted screws design instead of ball and socket. Also some are including strain gauges to measure the suction force and adjust exposure and retraction speed accordingly.

cheers,

Martin.

 

[Martin Wynne]

@Phil G

Hi Phil,

This is what happens for example on the switch heel chairs 3P..11P:

The tang needs to fit between two loose jaw pin slots. Consequently it can only cover a short length of the chair.

In my tests this is adequate to hold the chair flat on the timber. If there is a worry about that, some glue could be put on the ends of the plug before fitting.

In theory it might be possible to fit a second short tang at the far end, but that's a lot of extra coding I'd rather not get involved with for the present.

This is the L1 bridge chair:

The tang is even shorter. But the chair is short and dumpy, so this tang is sufficient. But adding glue or sealant is always possible if felt necessary. Just don't get any in the pin slot.

cheers,

Martin.

 

[Phil G]

Hi Martin,
Thanks for the explanation it makes more sense now.
Cheers
Phil,

 

[Steve_Cornford]

Hi Martin,
Out of interest, what will be the order of filing the switch blades?
Will there be any bending of rail between or after filing ooerations?
Steve

 

[Martin Wynne]

'
This is the worst clip-fit case, the EF chair on the vee exit:

Because of the dual pin slots in the middle, the only place for the clip-fit tangs is at the end. It is crying out for a second set of tangs at the other end. But having two sets will mean a significant rewrite of the data structure, and I just can't do it if I'm ever going to get another update out. It will have to stay like this for now. There are 3 solutions:

1. put a bit of glue on the far end, or

2. use a snap-fit plug instead of clip-fit for this chair. It will have to go in a separate STL file with any other snap-fit chairs. (The loose jaws can be in either file.), or

3. use solid jaws for this chair and modify the assembly sequence accordingly.

In contrast the CD/ED chair has no slots, and its single set of tangs can therefore be the full length. (In Templot for 00/EM etc. the rails are located in this chair by means of the separate locking spacer block. The prototype has inside keys.)

cheers,

Martin.

 

[Martin Wynne]

Hi Martin,
Out of interest, what will be the order of filing the switch blades?
Will there be any bending of rail between or after filing ooerations?
Steve

@Steve_Cornford

Hi Steve,

Same as making blades by hand:

1. file back of blade.

2. put filed blade in front filing jig and file front of blade. It won't fit if the back hasn't been filed.

3. put a slight set in the blade where the planing runs out to return the gauge-face into line.

cheers,

Martin.

 

[Steve_Cornford]

Hi Martin,
For the EF chair could you put the tangs on the ends of the plug rather than the sides?
Orthognal Steve!

 

[Steve_Cornford]

Blade filing
Does that mean that the planning on the back has been compensated to allow for the set?
Intrigued Steve

 

[Martin Wynne]

Hi Martin,
For the EF chair could you put the tanfs on the ends of the plug rather than the sides?
Orthognal Steve!

Hi Steve,

Definitely not. That's two sets of tangs, a modified socket and the ends are critical for setting the track gauge.

I am wondering about running the pin slots straight through the tangs, and seeing what 3D Builder makes of it!

I expect in the end I shall set to and do the work for more than one set of tangs. Almost certainly it will come up again in the K-crossings and slips.

cheers,

Martin.

 

[Martin Wynne]

Blade filing
Does that mean that the planning on the back has been compensated to allow for the set?
Intrigued Steve

@Steve_Cornford

Hi Steve,

See:

https://85a.uk/templot/club/index.php?threads/experimental-plug-track-continued.673/post-7327

1:88 planing on the back of a 1:32 B-blade (multiply by 2.75):

Worked fine when I tried it -- planing length spot-on at 29.3mm. I can't show a photo because this jig is now somewhere between Wells and Ludlow.

cheers,

Martin.