Re: Rolling Stock for Banavie Road
- Thread starter JimG
- Start date
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
I've been fairly successful with removable roofs. I construct an inner ledge just below the top off the sides and that ledge can be quite wide to give stability to the top of the sides. I then make the roof to plug into the recess on the top of the coach. Problems I have had is making a roof which won't warp through time and I might look at milling a wooden core to try and avoid this. I have had a fair amount of success with roofs in the past, but the occasional one goes banana.
I'm still thinking about glazing and I'll have to come to a decision soon since what I do has a major influence on how I build the sides. Certainly I would want the ability to place the glazing after painting.
I'm still using the original MekPak - I got a gallon can in the 1970s to share around fellow modellers and I'm still using the residue - about a litre.
I quite like it because it is slightly slower to set and allows some adjustment before setting. If I want a quicker, stronger action, I use Butanone which I have for my track making. I've still got, and using, my original Slaters brush bought from George himself at the first Glasgow exhibition in the 1960s. 
I have to confess that the ability to churn out another panelled side at the touch of a button (so to speak) has given me the luxury of doing test builds. In the past, the thought of re-doing a panelled side tended to make you put up with results which were not quite as good as you wanted.
Jim.
Steph Dale said:
I've been fairly successful with removable roofs. I construct an inner ledge just below the top off the sides and that ledge can be quite wide to give stability to the top of the sides. I then make the roof to plug into the recess on the top of the coach. Problems I have had is making a roof which won't warp through time and I might look at milling a wooden core to try and avoid this. I have had a fair amount of success with roofs in the past, but the occasional one goes banana.
I'm still thinking about glazing and I'll have to come to a decision soon since what I do has a major influence on how I build the sides. Certainly I would want the ability to place the glazing after painting.
I'm still using the original MekPak - I got a gallon can in the 1970s to share around fellow modellers and I'm still using the residue - about a litre.
I quite like it because it is slightly slower to set and allows some adjustment before setting. If I want a quicker, stronger action, I use Butanone which I have for my track making. I've still got, and using, my original Slaters brush bought from George himself at the first Glasgow exhibition in the 1960s. I have to confess that the ability to churn out another panelled side at the touch of a button (so to speak) has given me the luxury of doing test builds. In the past, the thought of re-doing a panelled side tended to make you put up with results which were not quite as good as you wanted.
Jim.
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
I spent yesterday messing around with my processes. I found that my Contiboard table was not flat. I should have checked it initially but made the mistake of assuming that it might have been made to fine limits. There was a three thou hump in the middle. So I machined the lot flat, then started looking at the Plastikard and found that the thicknesses were nominal at best. Thicknesses varied for my 30 thou stock from 25 thou up to 33 thou, but the really annoying feature is the variations within single sheets - one sheet varied by three thou from one edge to another.
So I might have a look at the Rowmark product to see if the thickness is more accurate. I'm not so worried about overall thickness since I can adjust the program to allow for varying thicknesses of sheet - what is difficult to cope with is variations within a sheet.
My other option is to deal with every styrene sheet as I did with the Contiboard and machine it flat to a stated thickness - say 28 thou - then continue on with the other milling. This would add a fair bit of time to the process. Or I just descend on the Slaters trade stand at an exhibition with a micrometer - David White will love that.
Jim.
28ten said:
I spent yesterday messing around with my processes. I found that my Contiboard table was not flat. I should have checked it initially but made the mistake of assuming that it might have been made to fine limits.
There was a three thou hump in the middle. So I machined the lot flat, then started looking at the Plastikard and found that the thicknesses were nominal at best. Thicknesses varied for my 30 thou stock from 25 thou up to 33 thou, but the really annoying feature is the variations within single sheets - one sheet varied by three thou from one edge to another. So I might have a look at the Rowmark product to see if the thickness is more accurate. I'm not so worried about overall thickness since I can adjust the program to allow for varying thicknesses of sheet - what is difficult to cope with is variations within a sheet.
My other option is to deal with every styrene sheet as I did with the Contiboard and machine it flat to a stated thickness - say 28 thou - then continue on with the other milling. This would add a fair bit of time to the process. Or I just descend on the Slaters trade stand at an exhibition with a micrometer - David White will love that.
Jim.
Phill Dyson
Western Thunderer
Plastikard Coaches for Banavie Road
I don't know if you are buying Slater's A4 sheets Jim?, but I buy sheets of plasticard from Eileen's which are approximately 69cm square for around £5 per sheet depending on thickness. I don't suppose the thickness is any more accurate than Slater's sheets though :scratch:
Phill :wave:
I don't know if you are buying Slater's A4 sheets Jim?, but I buy sheets of plasticard from Eileen's which are approximately 69cm square for around £5 per sheet depending on thickness. I don't suppose the thickness is any more accurate than Slater's sheets though :scratch:
Phill :wave:
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
Phil,
I'm not sure where my accumulated pile of styrene has come from. Certainly I used to buy the Slater's A4 sheets only, but then started buying larger sheets from other sources. And I picked up a pile of 30 thou from the workshop of the late Norman Pattenden and I'm not sure where Norman got his. I miught look at doing the overall truing cut to a specific thickness as I mentioned earlier, then I will know for certain what depth I'm dealing with. And I'll have a look at the Rowmark product that Cynric has mentioned which might be a more precise product dimensionally.
Jim.
Phill Dyson said:
Phil,
I'm not sure where my accumulated pile of styrene has come from. Certainly I used to buy the Slater's A4 sheets only, but then started buying larger sheets from other sources. And I picked up a pile of 30 thou from the workshop of the late Norman Pattenden and I'm not sure where Norman got his. I miught look at doing the overall truing cut to a specific thickness as I mentioned earlier, then I will know for certain what depth I'm dealing with. And I'll have a look at the Rowmark product that Cynric has mentioned which might be a more precise product dimensionally.
Jim.
28ten
Guv'nor
Plastikard Coaches for Banavie Road
Variation in material thickness is a problem, not just for milling but for the laser cutter as well.
I have just dug out MRJ 140 with the Gordon Gravett article. Having skimmed it he recommends ABS fixed with cyano and perspex or cast acrylic glazing, both of which I can laser :scratch:
Well worth reading for anyone contemplating and sort of DMU scratchbuild, I am sure Simon could supply a copy of the magazine for those interested
Variation in material thickness is a problem, not just for milling but for the laser cutter as well.
I have just dug out MRJ 140 with the Gordon Gravett article. Having skimmed it he recommends ABS fixed with cyano and perspex or cast acrylic glazing, both of which I can laser :scratch:
Well worth reading for anyone contemplating and sort of DMU scratchbuild, I am sure Simon could supply a copy of the magazine for those interested
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
A week passes and what have I got to show - well a few more sides and some ends.
At the top are four sides for the four compartment first coaches. The Caledonian normally ran these coaches in rakes of five with an all first in the middle which was sandwiched between two all thirds then there was a brake third at each end. I want to make two rakes, so I've got my full complement of all first sides.
Below is one side of a brake third. I'm still experimenting with this coach to work out how I will build it to incorporate the large birdcage style end to the brake.
Below that are two all third sides with the matching lower panelled sides. I will use these to build the first trial coach since the all third sides are the weakest with a large amount of hole space in them. If I can get the coach constructed to hold these sides flat and square, then the other coaches should be OK. These all third sides have been flattened. When I release the sides from the double sided tape, they take up a curl as a result of the peeling action I have to use. I have had a trial at flattening them and it has worked very well. I clamp the sides between two bits of flat alloy strip (from B&Q) using spring clothes pegs, and pop the lot in the oven at 100C for about ten to fifteen minutes, and they come out nice and flat. I could use boiling water which would probably be a fair bit quicker but the oven is easy.
At the bottom is one brake end and a couple of ordinary coach ends. The other part next to the brake end is a former to help construct the brake end with its duckets. On reflection, I should have cut the two forward facing ducket windows on this former.
It doesn't seem a lot for quite a busy time working on them. But I'm finding out about CNC as i go and I've hit a few mini brick walls on the way. And I also have sympathy with etched kit designers, with having to work out how things fit together.
Jim.
A week passes and what have I got to show - well a few more sides and some ends.
At the top are four sides for the four compartment first coaches. The Caledonian normally ran these coaches in rakes of five with an all first in the middle which was sandwiched between two all thirds then there was a brake third at each end. I want to make two rakes, so I've got my full complement of all first sides.
Below is one side of a brake third. I'm still experimenting with this coach to work out how I will build it to incorporate the large birdcage style end to the brake.
Below that are two all third sides with the matching lower panelled sides. I will use these to build the first trial coach since the all third sides are the weakest with a large amount of hole space in them. If I can get the coach constructed to hold these sides flat and square, then the other coaches should be OK. These all third sides have been flattened. When I release the sides from the double sided tape, they take up a curl as a result of the peeling action I have to use. I have had a trial at flattening them and it has worked very well. I clamp the sides between two bits of flat alloy strip (from B&Q) using spring clothes pegs, and pop the lot in the oven at 100C for about ten to fifteen minutes, and they come out nice and flat. I could use boiling water which would probably be a fair bit quicker but the oven is easy.
At the bottom is one brake end and a couple of ordinary coach ends. The other part next to the brake end is a former to help construct the brake end with its duckets. On reflection, I should have cut the two forward facing ducket windows on this former.
It doesn't seem a lot for quite a busy time working on them. But I'm finding out about CNC as i go and I've hit a few mini brick walls on the way.
And I also have sympathy with etched kit designers, with having to work out how things fit together. Jim.
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
Just an update since I've been doing a fair bit of experimenting over the past month or so. The picture below shows some of the work.
At the top are some North british four wheeled coach sides for another member of the S Scale Society. This coach is very similar to my Caledonian ones - maybe both being designed by Drummond might be a clue. Below them are a pair of two compartment testers from Caledonian 45 foot bogie coach drawings. This experiment is my first attempt at producing bolections on the quarter light window frames and I have had limited success so far. I have to do a bit more experimenting with tool feed rates to get the contours I want, It needs a lot of hand coding in Gcode to do this with the software I've got at the moment, so experimenting takes a fair bit of time.
At the bottom are two 3mm scale sides for the Caledonian first coach. I thought I might see how things look in the smaller scales and I had cutters which were small enough in diameter to allow me to go down to 3mm scale. I might try 2mm scale but the only problem is that the cost of the cutters goes up exponentially as the size gets very small.
I'll be on the S scale stand at Railex tomorrow, Sunday, supposedly demonstrating, and I'll have all my bits and pieces with me, so pop by if you want to see the sides "in the flesh".
Jim.
Just an update since I've been doing a fair bit of experimenting over the past month or so. The picture below shows some of the work.
At the top are some North british four wheeled coach sides for another member of the S Scale Society. This coach is very similar to my Caledonian ones - maybe both being designed by Drummond might be a clue.
Below them are a pair of two compartment testers from Caledonian 45 foot bogie coach drawings. This experiment is my first attempt at producing bolections on the quarter light window frames and I have had limited success so far. I have to do a bit more experimenting with tool feed rates to get the contours I want, It needs a lot of hand coding in Gcode to do this with the software I've got at the moment, so experimenting takes a fair bit of time.At the bottom are two 3mm scale sides for the Caledonian first coach. I thought I might see how things look in the smaller scales and I had cutters which were small enough in diameter to allow me to go down to 3mm scale. I might try 2mm scale but the only problem is that the cost of the cutters goes up exponentially as the size gets very small.
I'll be on the S scale stand at Railex tomorrow, Sunday, supposedly demonstrating,
and I'll have all my bits and pieces with me, so pop by if you want to see the sides "in the flesh".Jim.
40126
Western Thunderer
Plastikard Coaches for Banavie Road
JimG said:Just an update since I've been doing a fair bit of experimenting over the past month or so. The picture below shows some of the work.
[attachimg=1]
At the top are some North british four wheeled coach sides for another member of the S Scale Society. This coach is very similar to my Caledonian ones - maybe both being designed by Drummond might be a clue.
At the bottom are two 3mm scale sides for the Caledonian first coach. I thought I might see how things look in the smaller scales and I had cutters which were small enough in diameter to allow me to go down to 3mm scale. I might try 2mm scale but the only problem is that the cost of the cutters goes up exponentially as the size gets very small.
I'll be on the S scale stand at Railex tomorrow, Sunday, supposedly demonstrating,
Jim.
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
As you might have seen in the previous message, I had started trying to reproduce bolections which was quite a noticeable feature of many panelled coaches. David Jenkinson had a method which looked fairly easy but which I didn't find easy when I tried it. I had several attempts trying to develop other methods to produce a good result - like heat moulding thin plastic rod to go round the window to be the bolection protrusion and trying to emulate the sloping inner side of the bolection by having a slightly smaller frame in the window opening and filling between the plastic rod and the backing with intentionally thick paint to form a sloping shape. It did work after a fashion, but it took forever to do. So I was determined that I would form bolections with the CNC machine.
I started of with a small sampler of two compartments. These were based on the McIntosh 45ft bogie stock and had the later, simpler style of panelling to the Drummond four wheeled stock. When I do the basic panelling on the coaches, I use 2D methods and software. The additional information added is the depth of a cut or an area to the 2D information. This machine code from this method machines quite quickly, especially if I change cutters to get the optimum size and feed rate during the job. To do a 3D object like a bolection moulding requires that I use 3D software. Technically I could do the whole coach side in 3D but that could take many hours to do and I decided to mix 2D and 3D to get the shortest time for the process.
The first job was to cut the basic panelling and window openings using the 2D software. At the end of the process, the side looked like this....
The waste material in the openings has been left in, held in place by a very thin layer of Plastikard. I could cut right through but that could mean the cutter damaging the face of my very expensive holding mat and as a Scot, I can't allow that. So I aim to leave about one thou at the bottom of openings to act as a safety barrier. I also make sure that the 30 thou Plastikard is there or thereabouts in thickness. Try measuring the thickness of styrene sheets with a vernier or a micrometer - you can find a wide variation in thickness - sometimes on one sheet. 
Around the quarter light I have machined a rectangular section with the 2D software which will be the base material for the bolection. I then start cutting that section with the 3D code and produce the bolection moulding around each window. Here is an oblique close up of one of the compartments - also showing the droplight frame cut in place - as another experiment.
And now a broadside shot of the complete side.
Apologies for not cleaning the part up completely. You don't see all these small rags and hairs until you blow the pictures up to much more than life size But I'm happy with the result. The first attempt last week did not look all that good - the bolection hardly protruded at all from the panelled surface. But I had a session with the machine at the start of this week and found out about backlash which had been flattening the section. I found out that I am able to apply backlash compensation, which I did, and the result is what I had hoped for. In fact I might look at reducing the protrusion since it might be a bit too much. It scales to 3/8" in S scale.
The next move is to write some software that might speed up the 3D work in the way that the section is cut. I'll let the commercial software do all the hard work with the co-ordinate geometry, then I'll take the results and modify the machining paths. Good fun
Jim.
As you might have seen in the previous message, I had started trying to reproduce bolections which was quite a noticeable feature of many panelled coaches. David Jenkinson had a method which looked fairly easy but which I didn't find easy when I tried it. I had several attempts trying to develop other methods to produce a good result - like heat moulding thin plastic rod to go round the window to be the bolection protrusion and trying to emulate the sloping inner side of the bolection by having a slightly smaller frame in the window opening and filling between the plastic rod and the backing with intentionally thick paint to form a sloping shape. It did work after a fashion, but it took forever to do. So I was determined that I would form bolections with the CNC machine.
I started of with a small sampler of two compartments. These were based on the McIntosh 45ft bogie stock and had the later, simpler style of panelling to the Drummond four wheeled stock. When I do the basic panelling on the coaches, I use 2D methods and software. The additional information added is the depth of a cut or an area to the 2D information. This machine code from this method machines quite quickly, especially if I change cutters to get the optimum size and feed rate during the job. To do a 3D object like a bolection moulding requires that I use 3D software. Technically I could do the whole coach side in 3D but that could take many hours to do and I decided to mix 2D and 3D to get the shortest time for the process.
The first job was to cut the basic panelling and window openings using the 2D software. At the end of the process, the side looked like this....
The waste material in the openings has been left in, held in place by a very thin layer of Plastikard. I could cut right through but that could mean the cutter damaging the face of my very expensive holding mat and as a Scot, I can't allow that.
So I aim to leave about one thou at the bottom of openings to act as a safety barrier. I also make sure that the 30 thou Plastikard is there or thereabouts in thickness. Try measuring the thickness of styrene sheets with a vernier or a micrometer - you can find a wide variation in thickness - sometimes on one sheet. Around the quarter light I have machined a rectangular section with the 2D software which will be the base material for the bolection. I then start cutting that section with the 3D code and produce the bolection moulding around each window. Here is an oblique close up of one of the compartments - also showing the droplight frame cut in place - as another experiment.
And now a broadside shot of the complete side.
Apologies for not cleaning the part up completely. You don't see all these small rags and hairs until you blow the pictures up to much more than life size
But I'm happy with the result. The first attempt last week did not look all that good - the bolection hardly protruded at all from the panelled surface. But I had a session with the machine at the start of this week and found out about backlash which had been flattening the section. I found out that I am able to apply backlash compensation, which I did, and the result is what I had hoped for. In fact I might look at reducing the protrusion since it might be a bit too much. It scales to 3/8" in S scale.The next move is to write some software that might speed up the 3D work in the way that the section is cut. I'll let the commercial software do all the hard work with the co-ordinate geometry, then I'll take the results and modify the machining paths. Good fun
Jim.
Dog Star
Western Thunderer
Plastikard Coaches for Banavie Road
Thank you for sharing the trials and tribulations of this method.... the results look very, very, nice. Now, how long to machine one side of a GWR 70' toplight break third?
The photographs suggest that you have conquered the production of a panelled coach where the side is "of a level"... to push the frontier, how would you approach the GWR coaches which have recessed doors? (for example: the Dreadnoughts and Concertinas)
regards, Graham
Thank you for sharing the trials and tribulations of this method.... the results look very, very, nice. Now, how long to machine one side of a GWR 70' toplight break third?
The photographs suggest that you have conquered the production of a panelled coach where the side is "of a level"... to push the frontier, how would you approach the GWR coaches which have recessed doors? (for example: the Dreadnoughts and Concertinas)
regards, Graham
Steph Dale
Western Thunderer
Plastikard Coaches for Banavie Road
Jim,
I'd be interested to know the answers to something like that too! The panelling of the coach you've done is, on first impressions, close to that of LSWR stock of the type I'm interested in modelling. I'm perfectly happy using Jenks techniques, but I'd be interested to find a way of comparing processing time for your method with his...
I'm still not sure I'd necessarily go the CNC route anyway, I find hand-building plasticard coaches a rewarding passtime of it's own accord.
I'm also currently assuming that the methods of turning these sides into coaches wouldn't be too different from those promoted by Jenkinson? Or do you have ideas in that regard too?
Steph
Dog Star said:
Jim,
I'd be interested to know the answers to something like that too! The panelling of the coach you've done is, on first impressions, close to that of LSWR stock of the type I'm interested in modelling. I'm perfectly happy using Jenks techniques, but I'd be interested to find a way of comparing processing time for your method with his...
I'm still not sure I'd necessarily go the CNC route anyway, I find hand-building plasticard coaches a rewarding passtime of it's own accord.
I'm also currently assuming that the methods of turning these sides into coaches wouldn't be too different from those promoted by Jenkinson? Or do you have ideas in that regard too?
Steph
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
Graham, Steph,
It took about 105 minutes to machine the two compartment side on show - 32 minutes to do the basic panelling and 73 minutes to do the 3D cutting of the four bolection frames. You can see the large time requirement for relatively small amounts of product for full 3D milling. However I am working on speeding a lot of it up and the times I am getting now are very much shorter than when I started out. The easiest way to speed things up is to increase the speed of feed of the cutters and I can do that until I find my fastest speed empirically by breaking a tool under load.
On the 3D bolection cutting, I have speeded that up by splitting a complete bolection frame into four parts so that I only cut the actual frames. If I take the bolection frame as a whole, then the tool spends a huge amount of time cutting air in the window space. That's with the software I've got now which cost £200. I believe that I can get software that will allow me to machine selected areas but the price starts at £1100 and I think I prefer to do a bit of code hacking. However I can speed the 3D cutting up by increasing the increment between tool passes. At the moment I have gone for very high finish quality with very fine increments, but if I double the increment, I would half the time taken. However I'm looking at using the commercial software to generate data which I can use to generate code which will give a faster cutting operation. I would write my own software to do this, but use the commercial software to generate the co-ordinate data to use. I'm getting a bit long in the tooth to start coding for full blown 3D geometric calculating
For the difficult coaches with recessed doors, etc., I would follow David Jankinson's methods. What I am doing in CNC is produce the sides and cut out the panelling, windows. Then the coaches will be built using DJ's methods. I have actually produced the sides for the inner box with CNC to cut out all the openings to match the window cutouts. I could also cut out all the inner partitions and floors as well - probably with more accuracy than if I did it by hand Basically I'm automating the panelling and window cutting parts of DJ's method, otherwise everything else is to his words and music.
For the time taken for a 70 footer - technically nil, since my milling machine table can only deal with up to about 54ft in S scale. I am thinkiung of experimenting with some way of joining two or more parts to make a complete side of longer length, but that's in the future at the moment. But taking my times for the two compartment tester, it is about a fifth of the length of your 70 footer, so I would multiply by five for one side, and double it up for two sides - say between twelve and thirteen hours for two sides, and a major part of that would be cutting bolections if they were present (sorry, I don't know GWR coaching stock very well - more into Caledonian and Midland. ) If there were no bolections, then the time would come down to four to five hours.
I'll still try and get times down, but I am learning that CNC work can take a long time. I really started doing this because I found that I was having trouble cutting out panelling to an acceptable standard - a job I used to be able to do quite well - and if I wanted to model Edwardian Caledonian, then I had to find some way of building panelled coaches.. If it takes several hours to produce a pair of sides then that will probably be quicker than I would spend doing the job by hand, and now would be a damned sight more accurate. And you don't need to sit over the mill when it's working - I cooked my evening meal while the bolections were being cut.
Jim.
Graham, Steph,
It took about 105 minutes to machine the two compartment side on show - 32 minutes to do the basic panelling and 73 minutes to do the 3D cutting of the four bolection frames. You can see the large time requirement for relatively small amounts of product for full 3D milling. However I am working on speeding a lot of it up and the times I am getting now are very much shorter than when I started out. The easiest way to speed things up is to increase the speed of feed of the cutters and I can do that until I find my fastest speed empirically by breaking a tool under load.
On the 3D bolection cutting, I have speeded that up by splitting a complete bolection frame into four parts so that I only cut the actual frames. If I take the bolection frame as a whole, then the tool spends a huge amount of time cutting air in the window space. That's with the software I've got now which cost £200. I believe that I can get software that will allow me to machine selected areas but the price starts at £1100 and I think I prefer to do a bit of code hacking.
However I can speed the 3D cutting up by increasing the increment between tool passes. At the moment I have gone for very high finish quality with very fine increments, but if I double the increment, I would half the time taken. However I'm looking at using the commercial software to generate data which I can use to generate code which will give a faster cutting operation. I would write my own software to do this, but use the commercial software to generate the co-ordinate data to use. I'm getting a bit long in the tooth to start coding for full blown 3D geometric calculating For the difficult coaches with recessed doors, etc., I would follow David Jankinson's methods. What I am doing in CNC is produce the sides and cut out the panelling, windows. Then the coaches will be built using DJ's methods. I have actually produced the sides for the inner box with CNC to cut out all the openings to match the window cutouts. I could also cut out all the inner partitions and floors as well - probably with more accuracy than if I did it by hand
Basically I'm automating the panelling and window cutting parts of DJ's method, otherwise everything else is to his words and music.For the time taken for a 70 footer - technically nil, since my milling machine table can only deal with up to about 54ft in S scale.
I am thinkiung of experimenting with some way of joining two or more parts to make a complete side of longer length, but that's in the future at the moment. But taking my times for the two compartment tester, it is about a fifth of the length of your 70 footer, so I would multiply by five for one side, and double it up for two sides - say between twelve and thirteen hours for two sides, and a major part of that would be cutting bolections if they were present (sorry, I don't know GWR coaching stock very well - more into Caledonian and Midland. ) If there were no bolections, then the time would come down to four to five hours.I'll still try and get times down, but I am learning that CNC work can take a long time. I really started doing this because I found that I was having trouble cutting out panelling to an acceptable standard - a job I used to be able to do quite well - and if I wanted to model Edwardian Caledonian, then I had to find some way of building panelled coaches.. If it takes several hours to produce a pair of sides then that will probably be quicker than I would spend doing the job by hand, and now would be a damned sight more accurate.
And you don't need to sit over the mill when it's working - I cooked my evening meal while the bolections were being cut. Jim.
S
Simon Dunkley
Guest
Plastikard Coaches for Banavie Road
Forgive me if this is egg-sucking, or indeed a display of my ignorance in these matters (more likely!) but is it possible to get a large z-axis increment to remove the "meat" of the unwanted plasticard, and to then do a final cut which has less depth to it, to produce a good final finish?
Simon
Hi Jim,JimG said:
Forgive me if this is egg-sucking, or indeed a display of my ignorance in these matters (more likely!) but is it possible to get a large z-axis increment to remove the "meat" of the unwanted plasticard, and to then do a final cut which has less depth to it, to produce a good final finish?
Simon
JimG
Western Thunderer
Plastikard Coaches for Banavie Road
At the moment, everything seems possible. I'm feeling my way on how much cut I can apply before I run into problems with breaking cutters or, possibly, bad surface finish. By accident I found out that a 1mm carbide cutter will go through 30 thou Plastikard and the covering on Contiboard with no breakage - finger trouble on my part by not setting the Z axis up properly and the cutter ploughed through the work piece, the double sided tape and the Contiboard.
In a way I'm doing what you suggest just now with the coach sides I've done. I use a large diameter cutter to take down large areas of the workpiece and it will do it quite quickly. For example, to do the bolections, I cut down all the material round them so that they project by six thou. The same happens on the four wheel coaches where I take down the rest of the side round the lower panels - again done with a large diameter cutter moving quite quickly.
I really was pleasantly surprised with the quality of the machined surfaces. I was expecting some sort of tool marks that you expect when using an end mill on metal, and I was prepared to smooth them down to get an acceptable finish. I will now try upping all the feed speeds to the cutters to see if I can reduce time of machining and maintain a good finish. I can also adjust the depth of cut as well. I started off with very conservative depths since I was afraid of tool breakage. At the moment I have set the depths such that a tools has to take at least three cuts round a window opening in 30thou sheet. I think I can up the depth of cut so that the cutting out of a window would just take two trips round the periphery.
Jim
PS OT Robin is now taking over the form tool enquiry and has already made contact with the company.
Simon Dunkley said:
At the moment, everything seems possible.
I'm feeling my way on how much cut I can apply before I run into problems with breaking cutters or, possibly, bad surface finish. By accident I found out that a 1mm carbide cutter will go through 30 thou Plastikard and the covering on Contiboard with no breakage - finger trouble on my part by not setting the Z axis up properly and the cutter ploughed through the work piece, the double sided tape and the Contiboard. In a way I'm doing what you suggest just now with the coach sides I've done. I use a large diameter cutter to take down large areas of the workpiece and it will do it quite quickly. For example, to do the bolections, I cut down all the material round them so that they project by six thou. The same happens on the four wheel coaches where I take down the rest of the side round the lower panels - again done with a large diameter cutter moving quite quickly.
I really was pleasantly surprised with the quality of the machined surfaces. I was expecting some sort of tool marks that you expect when using an end mill on metal, and I was prepared to smooth them down to get an acceptable finish. I will now try upping all the feed speeds to the cutters to see if I can reduce time of machining and maintain a good finish. I can also adjust the depth of cut as well. I started off with very conservative depths since I was afraid of tool breakage. At the moment I have set the depths such that a tools has to take at least three cuts round a window opening in 30thou sheet. I think I can up the depth of cut so that the cutting out of a window would just take two trips round the periphery.
Jim
PS OT Robin is now taking over the form tool enquiry and has already made contact with the company.
28ten
Guv'nor
Plastikard Coaches for Banavie Road
Just catching up on this, those sides really do look very good. As they are non commercial I wouldnt worry about the time they take to complete, anyway its only a fraction of the time it takes to draw and program the cuts. It takes me longer to draw up the parts and program the laser path than it would to cut parts by hand, the payoff is, as you say, the accuracy that cant be achieved by convention means (at least not by me!)
Just catching up on this, those sides really do look very good. As they are non commercial I wouldnt worry about the time they take to complete, anyway its only a fraction of the time it takes to draw and program the cuts. It takes me longer to draw up the parts and program the laser path than it would to cut parts by hand, the payoff is, as you say, the accuracy that cant be achieved by convention means (at least not by me!)
S
Simon Dunkley
Guest
Plastikard Coaches for Banavie Road
Having seen and handled some finished parts at Railex last weekend, I have to say that the quality of the finished product was quite remarkable and a testament to Jim's care and determination to succeed at this.
Having seen and handled some finished parts at Railex last weekend, I have to say that the quality of the finished product was quite remarkable and a testament to Jim's care and determination to succeed at this.