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SteveO
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I've never used 3D PDFs before – brilliant!
Re: Rolling Stock for Banavie Road
- Thread starter JimG
- Start date
SimonT
Western Thunderer
It's one of the good points of Alibre (Or Geomagic as it is now) that it can output pdfs in this way. It's most fun if you pdf something large like a coach and then do out of control mouse in Reader. 30 seconds of silliness.
I am planning on assembling the carrier and wheels into the base and to then thread the spring through using pointed tweezers to ensure entry into the holes. I will then put the captive arm of the spring through the brake hanger and use the tweezers to hold the brake hanger in the slot and to then retain it with a dab of solder. The brake shoes will then go in with .7mm wire running through both shoes (as in Exactoscale) to allow final tweaking. The etch drawing now sports two 10BA clearance holes in the base to allow the w-iron assembly to be bolted to the floor of the vehicle (Mike Osbourne idea). Look forward to seeing the next experiment.
All the best
Simon
I am planning on assembling the carrier and wheels into the base and to then thread the spring through using pointed tweezers to ensure entry into the holes. I will then put the captive arm of the spring through the brake hanger and use the tweezers to hold the brake hanger in the slot and to then retain it with a dab of solder. The brake shoes will then go in with .7mm wire running through both shoes (as in Exactoscale) to allow final tweaking. The etch drawing now sports two 10BA clearance holes in the base to allow the w-iron assembly to be bolted to the floor of the vehicle (Mike Osbourne idea). Look forward to seeing the next experiment.
All the best
Simon
JimG
Western Thunderer
Just a step further on.
I started trying to saw a slot down to the spring wire hole, but then thought that I didn't really need the slot, and just filed out a notch in the corner. I don't really need a slot since the bearing carrier will hold the spring in the correct lateral position.
Again, the tabs are bent to retain the wire and an etch will have notches in the tabs to do the same. 0.0085" wire becomes invisible when it pings off the holders.
I left the "W" unfolded to better show the spring wire seatings. I'll fold it up and try the spring fitting with the wheels/axles/bearers in position.
Jim.
I started trying to saw a slot down to the spring wire hole, but then thought that I didn't really need the slot, and just filed out a notch in the corner. I don't really need a slot since the bearing carrier will hold the spring in the correct lateral position.
Again, the tabs are bent to retain the wire and an etch will have notches in the tabs to do the same. 0.0085" wire becomes invisible when it pings off the holders.
I left the "W" unfolded to better show the spring wire seatings. I'll fold it up and try the spring fitting with the wheels/axles/bearers in position.Jim.
SimonT
Western Thunderer
Jim,
very interesting; I look forward to seeing a completed unit. Unfortunately the design wouldn't work on vacuum braked stock with 8 brake shoes but it looks to ideal for your needs. Just finishing off the etch drawings and I need to give PPD a call to see if there is any chance of etching them this year!
Simon
very interesting; I look forward to seeing a completed unit. Unfortunately the design wouldn't work on vacuum braked stock with 8 brake shoes but it looks to ideal for your needs. Just finishing off the etch drawings and I need to give PPD a call to see if there is any chance of etching them this year!
Simon
JimG
Western Thunderer
I've now been messing around for a bit with trying out the best way of fitting the lot together and I'll post a few pictures later. One thing I am backing away from is wiggling the outer ends of the spring wire to get the spring in the righ position on the bearer. I'm getting very aware that I'm working on a unit out of the wagon underframe and that solebars, etc., might well limit the wiggle room necessary. So I've been having more thoughts while walking the dog and I'll try them out once I've fed her - which has to come first.
The etch I got a fortnight ago took just under a week turnaround from me emailing the file to the etch dropping through the letter box.
Jim.
JimG
Western Thunderer
The situation so far....
I've spent a fair bit of the afternoon messing around with putting the sprung axleguards together and I think I have decided on the following modus operandi which should work when the axleguard units are fitted in an underframe.
First the axle with the two bearing holders is inserted in the slots in the "W" irons with the bearing keepers upwards.
Then I start rotating the bearing carrier around and lightly spring it out to avoid the spring, which is already in place. The nearest carrier is still sticking up and the farther one has almost been rotated fully. I've left off the farther wheel so that you can see everything.
The bearing carrier is rotated until it clips into its final position between the guides on the "W" iron. The spring is caught between the bearing carrier and the inner side of the "W" iron, and has to be got round the other side of the bearing carrier to sit under the lug.
The bearing carrier is "lifted" until it hits the stops on the "W" iron. The easiest way to do this is to pull on the top of the wheel opposite, as I'm doing here.
The next action is to push the spring wire down and move it under the bearing carrier to rest on the lug in the inner side of the carrier. The temporary tool to do this is a watchmaker's screwdriver which I could get to do the job with a push and a small twist. I couldn't show this action properly because it actually needs two hands and I also had to hold the camera.
...and we finish up with the spring on the lug and the bearing holder fully sprung and operational.
I've also had a good few goes at this operation with a 3' 8" wheel on the axle and it works quite well with the screwdriver but I think I will make a tool to do the job better. I could actually do it by filing the screwdriver blade but I'd rather keep the screwdriver functional, and make something out of a bit of brass or steel rod.
For smaller 3' 2" wagon wheels, the spring can placed as above, or there is room to get a cocktail stick on to the spring from the inside and persuade it round onto the tab on the bearer.
The tool will probably be a 1.25mm rod filed to screwdriver blade shape. but with a short, sharp projection at one end. The sharp projection will be pushed down against the back of the "W" iron to get behind the spring and push it down, then if the tool is rotated, the spring will be moved out under the end of the bearer to locate onto the lug. With the tool being 1.25mm wide, the spring can't be moved too far to jump over the end of the lug which projects approximately 1.7mm from the back of the "W" iron.
To remove the axle and bearings it's almost exactly the reverse, with the tool used to push down the wire and rotate to get it behind the bearer, then persuade the bearers out over the lugs on the "W" irons and pull the axle up and out of the "W" irons. You can also just release and withdraw the springs instead of using the tool.
I have found that I now don't need the slot or cutout for the spring at the clamping end so will just leave it as a hole as original.
I think that I've now got a setup which can be worked on with the "W" irons fixed in the underframe, and the projections outside the frame of the "W" iron assembly are not too long - the lengths of the spring holding tabs on one side, and whatever length of spring projects on the other side.
Must get back to editing the Gazette.
Jim.
I've spent a fair bit of the afternoon messing around with putting the sprung axleguards together and I think I have decided on the following modus operandi which should work when the axleguard units are fitted in an underframe.
First the axle with the two bearing holders is inserted in the slots in the "W" irons with the bearing keepers upwards.
Then I start rotating the bearing carrier around and lightly spring it out to avoid the spring, which is already in place. The nearest carrier is still sticking up and the farther one has almost been rotated fully. I've left off the farther wheel so that you can see everything.
The bearing carrier is rotated until it clips into its final position between the guides on the "W" iron. The spring is caught between the bearing carrier and the inner side of the "W" iron, and has to be got round the other side of the bearing carrier to sit under the lug.
The bearing carrier is "lifted" until it hits the stops on the "W" iron. The easiest way to do this is to pull on the top of the wheel opposite, as I'm doing here.
The next action is to push the spring wire down and move it under the bearing carrier to rest on the lug in the inner side of the carrier. The temporary tool to do this is a watchmaker's screwdriver which I could get to do the job with a push and a small twist. I couldn't show this action properly because it actually needs two hands and I also had to hold the camera.
...and we finish up with the spring on the lug and the bearing holder fully sprung and operational.
I've also had a good few goes at this operation with a 3' 8" wheel on the axle and it works quite well with the screwdriver but I think I will make a tool to do the job better. I could actually do it by filing the screwdriver blade but I'd rather keep the screwdriver functional, and make something out of a bit of brass or steel rod.
For smaller 3' 2" wagon wheels, the spring can placed as above, or there is room to get a cocktail stick on to the spring from the inside and persuade it round onto the tab on the bearer.
The tool will probably be a 1.25mm rod filed to screwdriver blade shape. but with a short, sharp projection at one end. The sharp projection will be pushed down against the back of the "W" iron to get behind the spring and push it down, then if the tool is rotated, the spring will be moved out under the end of the bearer to locate onto the lug. With the tool being 1.25mm wide, the spring can't be moved too far to jump over the end of the lug which projects approximately 1.7mm from the back of the "W" iron.
To remove the axle and bearings it's almost exactly the reverse, with the tool used to push down the wire and rotate to get it behind the bearer, then persuade the bearers out over the lugs on the "W" irons and pull the axle up and out of the "W" irons. You can also just release and withdraw the springs instead of using the tool.
I have found that I now don't need the slot or cutout for the spring at the clamping end so will just leave it as a hole as original.
I think that I've now got a setup which can be worked on with the "W" irons fixed in the underframe, and the projections outside the frame of the "W" iron assembly are not too long - the lengths of the spring holding tabs on one side, and whatever length of spring projects on the other side.
Must get back to editing the Gazette.
Jim.
SimonT
Western Thunderer
Jim,
very impressed by the apparent simplicity of the design. I do like anything that obeys the KISS principle.
My impression about the etchers was that they are so overloaded with work that they take ages. If it is a couple of weeks I will try to make a similar photo sequence of my design of W-iron but rather than hijack your thread I will place on a work thread of my own.
Thanks Jim.
Simon
very impressed by the apparent simplicity of the design. I do like anything that obeys the KISS principle.
My impression about the etchers was that they are so overloaded with work that they take ages. If it is a couple of weeks I will try to make a similar photo sequence of my design of W-iron but rather than hijack your thread I will place on a work thread of my own.
Thanks Jim.
Simon
JimG
Western Thunderer
Simon,
I'll probably get my artwork finished next week once I've got other more pressing matters out of the way. It's about 50% there at the moment and only needs the holding tabs included and the outrigger removed. I'm thinking of just doing a smaller test etch to check out some other ideas, the main one being providing a metal underfloor with sets of peg holes to match peg holes on the "W" iron etches to allow placement for the various different wheelbases of Scottish wagons. The metal underframe will fit inside the solebars and buffer beams and on the underside of the floor of a wagon and will provide a base to locate the wheelbase accurately and to solder brake gear to as well as other things like AJ couplers, etc. The only consideration I have at the moment is with the length of the underfloor since there are quite a few permutations of overall length to wheelbase. The simplest way is to allow for the longest length then mark and cut it for shorter prototypes. I think that trying to provide half etched breaking lines at the ends for all possibilities might not be feasible. Since other users of these "W" irons will be S scale modellers who have to be scratchbuilders, trimming a floor to length should not be a problem.
But I might do some more investigation into the variation in wagon lengths to work out what the permutations are. I do have Mike Williams excellent book on Caledonian wagons which will make research easy and I'll see if Scott Willis (ScottW of this parish) has information about North British wagons. John Holden of the S scale society has a lot of information about Highland Railway wagons so I can possibly tap that source for more information. The underfloor idea came from Scott in an email exchange.
Many thanks for the spring location idea.
Jim.
I'll probably get my artwork finished next week once I've got other more pressing matters out of the way. It's about 50% there at the moment and only needs the holding tabs included and the outrigger removed. I'm thinking of just doing a smaller test etch to check out some other ideas, the main one being providing a metal underfloor with sets of peg holes to match peg holes on the "W" iron etches to allow placement for the various different wheelbases of Scottish wagons. The metal underframe will fit inside the solebars and buffer beams and on the underside of the floor of a wagon and will provide a base to locate the wheelbase accurately and to solder brake gear to as well as other things like AJ couplers, etc. The only consideration I have at the moment is with the length of the underfloor since there are quite a few permutations of overall length to wheelbase. The simplest way is to allow for the longest length then mark and cut it for shorter prototypes. I think that trying to provide half etched breaking lines at the ends for all possibilities might not be feasible.
Since other users of these "W" irons will be S scale modellers who have to be scratchbuilders, trimming a floor to length should not be a problem. But I might do some more investigation into the variation in wagon lengths to work out what the permutations are. I do have Mike Williams excellent book on Caledonian wagons which will make research easy and I'll see if Scott Willis (ScottW of this parish) has information about North British wagons. John Holden of the S scale society has a lot of information about Highland Railway wagons so I can possibly tap that source for more information. The underfloor idea came from Scott in an email exchange.
Many thanks for the spring location idea.
Jim.
JimG
Western Thunderer
After getting all the other tasks out of the way, I got a chance to get back to the "W" irons and I've spent the last two days finalising a test etch to send to PPD.
This is the "W" iron module showing the red upper side and (in places) the blue lower side. the "W" iron assewmbleis are meant to sit on a 15thou metal sub floor in a wagon but in case a sub floor isn't required or wanted, the rectangles which house the bearing supports on the right can be used as pads when the supports are removed to get the "W" irons at the correct height.
This is the full test sheet I will be sending to PPD with three "W" iron modules and two test floors on the right. It hasn't come out well on this image but there are tabs in the floors which will locate in the rectangular holes in the "W" iron bases and there is a selection of wheelbases, from 8' 0" to 12' 0" in 6" increments. This was a suggestion by Scott (ScottW). This will cover the majority of NB and Caledonian wagons. I've also etched a longitudinal and latitudinal centre line on the floors to help in setting up. In use, the floors will be cut to length to match the distance between the inside of the solebars of the wagon being modelled. I am thinking about the possibility of etching various cutting lines on the floors to ease adjusting the length of the floors, but that will require a lot more research to find out all the possible lengths required. My gut feel is that there will be too many options to make etching all of them practical - possibly leaving the ends of the floors looking like corrugated iron.
I'll email the file to PPD tomorrow and, with a bit of luck, might have the etch back by the end of next week. So I'll dust off the milling machine and get that goign again. It's had a fair rest for the last few weeks.
Jim.
This is the "W" iron module showing the red upper side and (in places) the blue lower side. the "W" iron assewmbleis are meant to sit on a 15thou metal sub floor in a wagon but in case a sub floor isn't required or wanted, the rectangles which house the bearing supports on the right can be used as pads when the supports are removed to get the "W" irons at the correct height.
This is the full test sheet I will be sending to PPD with three "W" iron modules and two test floors on the right. It hasn't come out well on this image but there are tabs in the floors which will locate in the rectangular holes in the "W" iron bases and there is a selection of wheelbases, from 8' 0" to 12' 0" in 6" increments. This was a suggestion by Scott (ScottW). This will cover the majority of NB and Caledonian wagons. I've also etched a longitudinal and latitudinal centre line on the floors to help in setting up. In use, the floors will be cut to length to match the distance between the inside of the solebars of the wagon being modelled. I am thinking about the possibility of etching various cutting lines on the floors to ease adjusting the length of the floors, but that will require a lot more research to find out all the possible lengths required. My gut feel is that there will be too many options to make etching all of them practical - possibly leaving the ends of the floors looking like corrugated iron.
I'll email the file to PPD tomorrow and, with a bit of luck, might have the etch back by the end of next week. So I'll dust off the milling machine and get that goign again. It's had a fair rest for the last few weeks.
Jim.
JimG
Western Thunderer
looking good Jim.
I have just acquired some test etches for a couple of NBR brake vans (details of which may appear at a later date) . The etches don't come with any W irons so I'd certainly be interested in acquiring some from you.
Scott,
I was aiming to send one of the "W" iron sets and one of the floors to you to see what you thought - that's if they work.
Jim.
JimG
Western Thunderer
I got the test sheet back from PPD this afternoon and it looks OK - no obvious mistakes on the part of the draughtsman have been found so far.
There are the three "W" iron etch groups and two floors.
A closer shot of one of the "W" iron groups. The "W" irons are designed to sit on a 15 thou nickel silver sub floor which fits on the underside of the wagon floor. If the floor is not used then the rectangular areas surrounding the bearing carriers (at the top) can be used to pad the "W" irons to the correct height.
The first assembly of the "W" irons and it went together quite well.
... and a closer shot of the method of locking the spring wire which works well.
However, I have some adjustments to make. I had played it a bit too safe in allowing for undercut in the bearing holes and slots for the 2mm bearings and the fit is a bit sloppy and I will make a small adjustment to compensate for the final etches. In my earlier etches, I had made the fit a bit too tight and filing and reaming were required to open them out to get things to fit. I also made the lugs that locate the top end of the bearing carriers not project as much to make fitting the carriers a bit easier, but I've gone a bit too far. When fitting the carriers, the spring wire is initially trapped between the carrier and the "W" iron and the carrier still has to locate between the lugs at this point. But with my new size, the carriers barely locate at this point making the placing of the spring a bit more of a fiddle than it should be. So I'll make the lugs a bit bigger. But overall I'm pleased with the outcome and the springing arrangement is a lot better than my original design - thanks to SimonT for his suggestion.
BTW, while waiting for the etches over the Christmas period, I ventured into loco wheel making again - this time a Caledonian 4' 6" wheel for a future Class 782 0-6-0T (the Caley "Jinty") and a future small Class 104 0-4-4T. You can see the first attempts at the top left of the first picture.
Jim.
There are the three "W" iron etch groups and two floors.
A closer shot of one of the "W" iron groups. The "W" irons are designed to sit on a 15 thou nickel silver sub floor which fits on the underside of the wagon floor. If the floor is not used then the rectangular areas surrounding the bearing carriers (at the top) can be used to pad the "W" irons to the correct height.
The first assembly of the "W" irons and it went together quite well.
... and a closer shot of the method of locking the spring wire which works well.
However, I have some adjustments to make. I had played it a bit too safe in allowing for undercut in the bearing holes and slots for the 2mm bearings and the fit is a bit sloppy and I will make a small adjustment to compensate for the final etches. In my earlier etches, I had made the fit a bit too tight and filing and reaming were required to open them out to get things to fit. I also made the lugs that locate the top end of the bearing carriers not project as much to make fitting the carriers a bit easier, but I've gone a bit too far. When fitting the carriers, the spring wire is initially trapped between the carrier and the "W" iron and the carrier still has to locate between the lugs at this point. But with my new size, the carriers barely locate at this point making the placing of the spring a bit more of a fiddle than it should be. So I'll make the lugs a bit bigger. But overall I'm pleased with the outcome and the springing arrangement is a lot better than my original design - thanks to SimonT for his suggestion.
BTW, while waiting for the etches over the Christmas period, I ventured into loco wheel making again - this time a Caledonian 4' 6" wheel for a future Class 782 0-6-0T (the Caley "Jinty") and a future small Class 104 0-4-4T. You can see the first attempts at the top left of the first picture.
Jim.
SimonT
Western Thunderer
Jim,
they look very good. Just to get a feel on spring performance, what diameter spring are you using, how long is it, what deflection do you get and what is the target weight of the wagons? Would it be useful if we pooled this info? If so I'll try to get the same info together on my ones.
Simon
they look very good. Just to get a feel on spring performance, what diameter spring are you using, how long is it, what deflection do you get and what is the target weight of the wagons? Would it be useful if we pooled this info? If so I'll try to get the same info together on my ones.
Simon
ScottW
Western Thunderer
Looking very good indeed Mr G. Your perseverance with the design of the W irons seems to be paying off.
Going off topic a bit, but as you mentioned wheels, I'd be very interested to see the results of the 4' 6" wheel. Is it specifically a Caledonian Railway wheel design? A number of NBR locomotives carried 4' 6" wheels and I'm looking for a number of them. The society does do a casting for a 4' 6" wheel but unfortunately they have been out of stock for sometime now-not that I'm in any rush.
Scott
P.S. Have you taken over as shopkeeper for the society?
Going off topic a bit, but as you mentioned wheels, I'd be very interested to see the results of the 4' 6" wheel. Is it specifically a Caledonian Railway wheel design? A number of NBR locomotives carried 4' 6" wheels and I'm looking for a number of them. The society does do a casting for a 4' 6" wheel but unfortunately they have been out of stock for sometime now-not that I'm in any rush.
Scott
P.S. Have you taken over as shopkeeper for the society?
JimG
Western Thunderer
I've done this to try and reproduce the very deep boss on the Caledonian locomotives - I think we discussed this some time ago when talking about your Caledonian tank loco. It could be that the Caledonian wheels are the same as the NB ones if Drummond brought his NB wheel designs across to the Caledonian.
This is the cross section taken from the official GA of the 782 class and the cross section on the 104 class GA I have looks the same.
This is the work so far - with the first attempt on the left and the second on the right. The profile on the first one was wrong - down to the programmer's fault
- and the spokes were too thin at the rim end. This was corrected on V2 and some some more shaping of the spokes has been carried out by hand with scrapers. But I've re-written the spoke profile code to minimise the ridging that you can see on the first attempt - basically halving the step distance of the round nosed cutter. It's not just 3D printing that can give you ridging/layering problems.I'm also re-jigging the way I'm making the wheels to overcome some of the problems I had with the Pug wheels. I'm now using the front of the rim of the spoke spider as the reference level, and the thickness of the rim will be cut in the lathe on a collet holder so that all rims are the same depth. This operation will also cut through the back of the spokes to release the waste showing on the left hand part - much the same as machining the backs of cast wheels to open up the spokes. There are a couple of reasons for this - to avoid a piece of waste in a spoke aperture coming loose and jamming and breaking a cutter if the spoke profile is cut fully through the material, and also to allow the use of a very small diameter cutter at the inner end of the spoke shaping which doesn't have the length to cut completely through the material.
Funnily enough Richard (Dikitriki) and I were discussing whether I should get these parts cast and I wasn't really convinced it would be worth the hassle since I only want ten at the moment and I would probably have to make at least four or six to make up a worthwhile master for lost wax casting. But if more were needed we could look at casting.
Not until the AGM when I will get all the trays of stock from Dave Provan. This might be a dangerous move since I heard that one of the largest user of parts was John Holden when he was Parts Officer.
Jim.
JimG
Western Thunderer
At the moment I am using 0.0085 guitar string and the length between support points is nominally 14mm. I haven't arrived at a wagon weight at the moment. I do remember the work done by Scale7 modellers some years ago on the best way of using Bernard Weller's Exactoscale spring axleguards and the general feeling seemed to be that the heavier the wagon, the better the springing system worked. I do have a Slaters wagon in my workshop with a lot of lead packed into its underframe.
So I'm working at developing a wagon underframe which will have a fair amount of weight - basically using brass section for solebars and buffer beams and fitting lead strip into the "U" section of the "W" iron etches. I will then caclutae the optimum wire to suit whatever I come up with.For calculations, I use Russ Elliot's formulae and data on the CLAG site :-
http://www.clag.org.uk/beam.html
I did produce an article for the S Scale Gazette a couple of years ago where I took Russ' formulae and drew up graphs for sizes and weight appropriate to S scale.
I used the 14mm graph to calculate the springs from my four wheel coach underframe and it worked out pretty well spot on. I design the "W" irons to have 1.0mm total travel with the rest position at the half way point so that there is +/- 0.5mm travel available. I think that if I need more travel than that, that I should re-visit my track building methods.
Jim.
SimonT
Western Thunderer
Jim,
very interesting. I am using .013 spring wire. The prototype wagon, which spent an hour being run about on the layout this afternoon, weighs 155gm; so approx 39 gm per wheel. The length between pivots is 23.5mm so I am off the scale of the graphs. So time for rusty mathematics! The W-iron allows up to 1mm movement from the null position. As I could see some axle movement I suspect that I am getting at least .5mm of flex from the spring.
Best of all, it didn't fall off.
Simon
very interesting. I am using .013 spring wire. The prototype wagon, which spent an hour being run about on the layout this afternoon, weighs 155gm; so approx 39 gm per wheel. The length between pivots is 23.5mm so I am off the scale of the graphs. So time for rusty mathematics! The W-iron allows up to 1mm movement from the null position. As I could see some axle movement I suspect that I am getting at least .5mm of flex from the spring.
Best of all, it didn't fall off
.Simon