Pakpaul's Workbench

[pakpaul]

The bench

When I introduced myself as Another one from Western Australia in January of this year, I did mention that my immediate focus was to reorganise my shed and part of this was to build a workbench in order do do some 1/32nd scale modelling.

At the time I thought this would be about a month as I had already worked out what I thought I needed, made most of the drawers for the two supports for the workbench top, and purchased the timber for the top. A few further thoughts occurred, and were incorporated, and as this was mainly woodwork and creating dust I wanted everything complete before I started modelling.

Now towards the end of May, I'm nearly there, two of the four walls of my shed are almost organised, and if I don't think of anything else, I should be making a start on my Slater's MR covered wagon in the next week or so. The shed is of a reasonable size 7 metres square.

Below is a photo of the workbench currently supporting the components for 5 doors while the varnish dries.



Powerpoints, wall cupboards, pegboard, and the cupboard waiting for doors beyond the bench, are some of the additions to the original plan! The thing in the bottom left hand corner is the end of the bed of my large lathe (the smallest one I could find when I lived in Indonesia; we will look at it later).

I also need to find a chair!

Paul

 

[pakpaul]

Making Model Channel and Other Sections

In PMV Races

I have done the solebars first because I don't like doing them (my first attempt on another kit was a disaster) and finding out that Simon and Roger have had problems didn't fill me with confidence either. I spent an hour last night running a square needle file down each fold line until a witness mark appeared on the rear of the solebar. Sounds a long time and it was, there was four feet of filing to do - time to upgrade to a coarser file I think!

There was then a brief discussion about using an Olfa P cutter or scrawker to deepen etch groves in order that a sharp right angle bends could be made to form a solebar channel, but the comment was made that the angle of the point of this cutter was less than 90 degrees and that it would not work. Looking at the P 450 cutter, it does seem that the angle at the tip of the cutter is less than 90 degrees.

Below is a poor quality photograph of the tip of this cutter which shows it to be closer to 90 degrees than expected.



As its my intention to scratch build some 1/32nd wagons I will need to make solebar channel and other sections and so to fill in the time while varnish was drying I thought a little experimenting would probably make life easier in the future, and in the next few posts I will set out my results.

If we are to get a sharp 90 degree bend then we have to bend slightly more than that in order that the final bend will stay at 90 degrees, so we probably need an angle of 100 to 110 degrees on the cutter. I did try to modify the blade from the P 450 cutter, but it was difficult to hold to regrind with an acceptable result, and so I used a blade from the larger P 800 cutter and got the following result



Its probably closer to 120 degrees, but it did work, but is better run in a groove already started with a standard cutter

The other thing is that the Olfa P blades are quite thin, in both cases they measure 0.021" which means at a 90 degree angle the maximum depth of cut to maintain the profile is half of the thickness and at say 120 degrees is only one quarter of the thickness. in view of this I took a thicker blade at .035" and reground that with the following result.



I now had three cutters to experiment with as below showing them roughly at the angle they would be used.



Next post I will show the results of using these cutters on 9 thou hard nickle silver, 19 thou half hard nickle silver and 15 thou half hard brass (still trying to get acceptable photographs).

Paul

 

[Steph Dale]

Paul,
Apologies if this in the egg sucking department, but are you aware that Stanley do a suitable blade too? They call it a 'laminate cutter' blade; here it is from Amazon (other E-tailers are available). I haven't got any at the mo, but they tend to be my first port of call when I'm using this approach on metals - keeping the real Olfa/Tamiya cutter(s) for styrene.
Steph

 

[pakpaul]

Making Model Channel and Other Sections

Steph,

Definately not in the egg sucking department, that Stanley blade does not appear to be on sale in Australia, I had a look for it this morning, and later on the net and could not find it here. If it is around the same thickness as a normal Stanley blade of just over 20 thou then in terms of depth of cut possible, it will not take us further. (I noticed on the amazon add that 0.6mm was written).

I now have some photos of what I did, they are not that special but do illustrate what was achieved.

Firstly on the left is the 19 thou ns with the one groove from the thicker cutter and on the left the 9 thou ns with two grooves, one from the unmodified P 450 cutter, and one from the modified P 800 cutter there was a witness on the back below the grooves.



There is no photo of the 15 thou brass as it looks the same as the 19 thou ns.

After cutting out the first 5mm of the lines, the shapes of the grooves on the 9 thou ns were as follows



and the groove in the 19 thou ns



On bending these to get a 90 degree angle, in the case of the 9 thou ns the groove from the unmodified cutter allowed a bend to about 80 degrees, bending more than this caused the metal to break along the groove. The groove from the modified cutter allowed a 90 degree bend as follows



Similarly using the modified cutter the results of the 15 thou brass and 19 thou ns were as follows





All quite acceptable results, but the brass was much easier to work with than the nickle silver, also with the modified cutters it was easier to use them in a groove already made by the unmodified cutter than on the plain metal. Also it was better to remove the first and last 5mm or so of the groove prior to bending. The cutter modifications were done by freehand grinding on a rest, and this may be the reason they did not want to follow a straight line without guidance.

Conclusion from the exercise is that provided we are dealing with material less than 10 thou or .25 mm thick, a modified cutter will enable bends of 90 degrees to be made by using a scrawker, preferably using softer material rather than hard nickle silver. With thicker material we need to make our own cutter, when I need to do this I will post further.

The other thing that I looked at was the actual dimensions of the iron and steel sections which would have been used for wagon construction and in the next post (with 6 images all I can see in typing this is one line of text at a time) I will give some examples as well as details of sites on the net where further information can be obtained.

Paul

 

[pakpaul]

Making Model Channel and Other Sections

Continuing on from the last post, below is a photo of the 19thou nickle silver showing on the left a 90 degree bend made in the plain material, and on the right the bend made after using the modified scrawker. I think it demonstrates that where we want a sharp outside to a bend the use of the modified scrawker is worth the effort.



I did mention in the previous post that I would discuss the full size dimensions and the history of them, and the best resource I found for this on the net was the "Historical Structural Steel Handbook" this is a 5Mb downloadable file, and give a rather technical description of the history of structural steelwork which includes angles, channels, tees, bulb iron and other shapes down to the small sizes used in wagon and other rolling stock construction. The downloaded document does not allow copies to be made of sections from it, so i have made a brief summary. I would liked to have provided a link in this post, but every time I tried to copy the link, I downloaded the document again. If you wish to look at it just google the title and you will be able to download a copy.

Rolled iron and later steel sections became available in the 1870's with iron being gradually replaced by steel such that only steel was available from 1900.

The available shapes were listed in manufacturers handbooks, by the late 1870's a range of shapes and sizes were developed which essentially carried through until the early 1920's, being incorporated in B.S. 4 which was first issued in 1903. (These shapes are shown in Dorman Long's handbook for 1906).

This standard was revised in 1921, which resulted in a slight reduction of the thickness of the sections - sizes are available in Dorman Long's handbook of 1924.

A further revision was made to the standard in 1932 which made more standard sections available, mainly in terms of the thicknesses available. The second world war had no real impact on the sizes of the sections, and the standard was reissued in 1962 - sizes are available in Dorman longs handbook for 1964.

As an example of the changes, below are the drawings for a 9" by 3" channel (as used by the GWR for its wagons) firstly from 1906
The section in 1924


There is no drawing for 1964 ( but note the angle of the inside of the short arms of the channel), just a table of dimensions as follows


Another section used by the GWR for Solebars was bulb iron, this is the section from the 1906 handbook (Dimensions unchanged in 1924)


The handbook does give further details of the size of the bulb which has a maximum thickness of 1.375", if you compare this with the drawings of the bulb iron section in Atkins , Beard and Tourret, this this would scale the dimension to less than 1".


The dimensions of the full range of sections can be found in a series of handbooks originally produced by Dorman Long which are available for download on their website www.dormanlongtechnology.com. Insert "history" in the search field and a list is provided. About 20 Mb per handbook.

The Bench

Progress photo - doors glued up awaiting hinges and handles, "virgin" A1 cutting mat in place. The left hand cupboard top has a granite insert to act as a surface plate.



Paul

 

[pakpaul]

Threading Rivets

In his Workbench thread

Here's the early coal wagon again but now fitted out with hinges et al. The next picture, when it comes, will show a completed wagon once again painted in the 'lavender grey' of the London and Brighton. Well, my version of lavender grey. The nuts, if you can see them, are all 16BA opened out to take a 1/32" rivet. The ones holding the W irons are still 16 BA but opened out and taped 14BA, a very good tip from a fellow modeller.

Jon

Some years ago (can't remember how many) I had a need to put a thread on a 1/32" rivet (also can't remember why but it was nothing to do with gauge 3 models) and devised a simple tool in order to do this. It so happens that the 1/32" or 0.8 mm rivet is very close to the outside diameter of a 16 BA thread, also imperial size rivets can be threaded 12 BA (3/64"), and 1/16" rivets can be threaded 10BA. I could not find any reference to threading rivets and so the tool design is 100% mine. The tool also can be used to thread the end of wire to make for example frame stays on wooden underframes.

In my varnish drying moments as well as looking at steel sections, I managed to dig out some examples of threaded rivets, as well as a home made coach bolt using a 14 BA thread, and these are illustrated below



The scale is the mm divisions of a rule, and left to right we have a 1/32" rivet threaded 16BA , 1 mm coach bolt with 14 BA thread, 3/64 rivet with 12 BA thread and finally 1/16" rivet with 10 BA thread, all with their respective nuts.

It is also possible to put a 14BA thread on a 3/64" rivet and this is shown below together with one threaded 12BA



The head of the rivet is not the correct shape for a coach bolt head, and so in another varnish drying moment a small mild steel punch was made, as well as a holder for a 1/32nd rivet, and several rivets (3 brass one copper) were treated to the application of a hammer to the punch (punch just placed on top of the rivet in the holder with no lining up or polishing of the punch) with the following result



I think the head shape looks much more like a coach bolt, the head being quite close to scale proportions, I have not shown a photo of the top of the head, as the punch is very much in need of polishing.

The tool to thread the rivet is a simple piece of lathe work to make a holder for the die and a corresponding one for the rivet, is there any interest in me giving a description. and/or refining the means of changing the shape of the rivet head.

Paul

 

[JimG]

Threading Rivets

The tool to thread the rivet is a simple piece of lathe work to make a holder for the die and a corresponding one for the rivet, is there any interest in me giving a description. and/or refining the means of changing the shape of the rivet head.

Paul,

By all means. I might not want to thread small rivets, but your methods might be useful for other things.

Jim.

 

[jamiepage]

Yes please, and thanks.

 

[Jon Nazareth]

Yes, please. I'd be very interested to see how you managed it.

Jon

 

[pakpaul]

Threading Rivets

I have remembered when and why I needed to thread a rivet, it was around 1995, and I had made a 1/8 scale model of a wheelbarrow from John Thompson drawings which needed 4 coach bolts, and rather than try and buy them from the UK, I decided to make them from 3/64 rivets and 12 BA nuts. It was made with hand tools apart from the wheel, starting off with a block of teak. Photos below.





My small Sherline lathe has a 5/8" diameter tailstock barrel, and I made a series of die holders from 1" diameter free machining aluminium to cover the small BA sizes for threading in the lathe, the die holders are all 1" long with the exception of the 16BA one and are shown below.



For threading a rivet, the die is reversed in the holder as below



The following 3 photos show a threaded rivet in its holder, and the components of the holder, this one is for a 3/64" rivet







The 12 on the holder just identifies the size of the hole as 1.2 mm which is as near as 3/64" as makes no difference.

Below is a photograph of a sketch of the cross section of the of the two components of the rivet holder. Clearly the only two dimensions which need to be adhered to are the diameter for the die, and for the rivet.

 

[pakpaul]

Threading Rivets

Sorry pressed the wrong button! Sketch below

In making the die holder, the central hole and the recess for the die should be made at the same setting to ensure concentricity.

In the case of the rivet holder the outside part need to be turned to a diameter that is a smooth running fit in the die holder, and the hole for the rivet should be drilled at the same setting. The item is then reversed in the chuck the 1/4" diameter hole is drilled, followed by the tapping drill for the thread and the clearance for the thread. A 1/4" slot drill is then used to create a flat bottom to the hole so that the central part will be able to get a grip on the rivet head to prevent it from turning when it is being threaded, but not to the degree that the rivet head is marked, The reason for the 1/4' diameter is to allow a pair of long nosed pliers to be used to turn the rivet should it get stuck in the die and the grip in the holder is not strong enough (it has happened to me once, it also makes it easier to insert the rivet). The centre part of the holder is plain turning, and the thread only needs to engage for about 5 or 6 turns to clamp the rivet properly.

The reason for the flange on the rivet holder is to get a better grip for hand tightening, similarly the use of a hexagon section for the central part. This is important where say a 3/64" rivet is threaded 14BA.

If you need to thread the end of a piece of wire then if it is held tightly in a pin vice the outside of the rivet holder can be placed in the die holder, and used to guide the wire into the die. It's easier and quicker than setting the die up in the lathe.

In the case of the rivet holder for 1/32nd rivets, the forces are very small and the setup in the photos below is sufficient





I hope the above makes sense, please let me know if any further clarification or detail is needed.

Paul

 

[adrian]

I hope the above makes sense, please let me know if any further clarification or detail is needed.

It does - a neat solution. Just so that I'm clear on my understanding, the brass plug just clamps the rivet in the rivet holder. The die holder with the die reversed then slides over the rivet holder to align the rivet with the centre of the die.

 

[pakpaul]

Adrian

Absolutely correct.

Paul

 

[JimG]

Paul,

Any thoughts on doing square nuts to go on the rivets.

Jim.

 

[Jon Nazareth]

.........and is there an easy way to make square nuts and bolts, real or dummy?

Jon

 

[JimG]

Jon,

A topic currently in Martin Wynne's Templot forum is discussing using Vero pins for track building. Martin measured ones that he had and the diameter of the pin head was 1.8mm and the diameter of the pin body was 1mm.

http://uk.rs-online.com/web/p/produ...KHM2kTfHfQ3yoEEdp4pol2tINiS4cgnTtoaAivR8P8HAQ

Many years ago the late Colin Binnie demonstrated to me a method he used to make very small hex heads for S scale models whereby he softened a piece of brass bar of the appropriate diameter then held it in a pin vice with a hexagonal barrel and used the hexagon to gauge the correct position as he squeezed the rod in a vice, rotating the rod/pin vice by 60 degrees and squeezing until he got a nice representation of a hex head. If you did something similar with the vero pins, but rotating 90 degrees, you might get a suitable outcome for square headed bolts. Note that the diameter of the body of the pin is 1mm, so just the right size for tapping to 14BA using Paul's methods.

Jim.

 

[Jon Nazareth]

Thanks, Jim, I'll keep that in mind. I did look up the site and they aren't that expensive.

Where is Martin Wynne's Templot forum?

Jon

 

[JimG]

Where is Martin Wynne's Templot forum?

Jon,

http://85a.co.uk/forum/

Jim.

 

[pakpaul]

Paul,

Any thoughts on doing square nuts to go on the rivets.

Jim.

.........and is there an easy way to make square nuts and bolts, real or dummy?

Jon

Sorry for not replying earlier, it has been a long weekend in Western Australia, and as it had been organised for me, only managed to get into my shed this afternoon, as I wanted to quickly try a couple of things before replying.

The result of this is as follows:



Not a flattering photograph! It does look better than this when its not magnified. The scale is millimetres and the thread is 14 BA. From this quick effort I think I have learned enough to make some sensible suggestions as to how to make these items. Will go into more detail tomorrow.

Paul

 

[pakpaul]

Square nuts and bolts

I seem to have lost a day thanks to work, just too tired yesterday evening to make a sensible post.

I did manage to revisit the square headed bolt with a better result



The first attempt used a carbide insert tool to reduce the diameter, this time a very sharp high speed steel cutter was used, also the original 1/8" diameter was reduced to .039" in one pass (the rod being held in a collet rather than the 3 jaw chuck), the tool being set marginally below centre height. after this the thread was made with a tailstock die holder. The rod was then placed in a square holder (top left in the photo below), and a square for the head made by placing the holder in the milling vice and rotating it 90 degrees after each cut.



There are two other square holders for 3/32" and 1/16" round bar, and also a hexagonal holder for 1/16" round bar is shown (the hexagonal holder was used to machine the sections shown in my thread on fastener sizes and scale equivalents). The square holders were machined in a 4 jaw self centering chuck, and were accurate to .001" which is sufficient I think. After the square is machined, the 1/8" rod is returned to the lathe and the bolt parted off.

This is the only realistic way of making threaded bolts, obviously if square material of the right size is available then the milling operation could be omitted. 0.069" square bar (in the case 0f 14BA) would have to be machined, or could in theory be drawn from round bar. Below is a picture of what I have collected for experiment later.



The wire is nickle silver, 2mm and 1.2 mm, and some tests have been made which were successful, but the major issue is that of straightening, and in the case of the square section removing any twist. I think for nuts and bolts nickle silver wire would not be the ideal raw material as it does not machine well, and it would be advisable to use leaded brass, which can be drawn but which would need more frequent annealing. This is high on the lists of things I want to experiment with, I think the main issue will be in annealing the leaded brass, I will report on it later but I don't think it will be very soon!

To return to scale threaded bolts, I think the only way to make then with a square head is to use the lathe and if necessary a mill to get the square head. If its in the lathe we might as well put the thread on using the lathe, but equally it could be put on using the rivet threading tool.

Also if we are looking at modelling wagons, particularly wooden bodied with wooden underarms, there will be few locations visible where anything other than coach bolt heads are visible,and so using a lathe for making bolts, although relatively time consuming may be acceptable.

To turn to cosmetic nuts, which could be either square or hexagonal, I think the bet approach is by CNC milling or engraving of styrene or other plastic such as ABS or acrylic.

Below is a photo of 1/32nd scale 7/8" whitworth bolts in styrene.



The size is roughly 1.5" by 2.5", and the spacing is determined by the diameter of the parallel engraving cutter used. In the case of the above sample the central hole dot was made with an engraving cutter, and this has resulted in the .55 mm drill used to cut oversize, or as can be seen to jump out of the dot. Future production will use a centre drill to mark the hole position which should avoid oversized or misplaced holes.

The styrene is held to the table of the machine by double sided tape, and there has to be a small thickness of material left (.001" - .002") to prevent the cutter from touching the double sided tape. The holes are drilled in a drill press as a separate operation, although possible to mount a drill in my engraver it is not worth the trouble involved in making a holder for the drill to fit in a 1/8" collet. After drilling the holes the individual nuts can be cut out. I did have trouble with this using a craft knife blade or a scalpel, but have had success recently using a very sharp wood chisel. It is possible to make the nuts down to scale 5/8" in 1/32nd scale. If the nut has a washer this can also be incorporated, and the resulting nut and washer cut out with a circular cutter as in the thread on fastener sizes and scale equivalents.

It terms of making threaded nuts then the only description I have ever seen of this was in the Model Engineer magazine and related to making 10BA square nuts for model horse drawn carriages. The approach was to drill the tapping hole size in appropriate thickness brass, and use this as a register for a home made punch tool to make the square nut blank, this blank was then put in a fixture and tapped. I have tried to find the article in the index, but have not been successful so far.

Another alternative is to use the lathe, but the number of nuts on a single wagon would make this impractical, and I think the most appropriate way to make then would be to use the CNC mill or engraver, as in the case with the cosmetic nuts, but using engraving brass of the appropriate thickness, superglued or soldered to a thin backing sheet. After milling or engraving to the full depth of the nut the tapping drill could be used and the nuts tapped. they could then be removed from the backing by heating.

For tapping very small threads, I made the following fixture



It is shown with a 14BA tap. the chuck is one that is sold for dremel drills, and cannot be tightened too much, apart from the brass adaptor for the chuck the rest is aluminium, and so the whole of the holder and guide for the tap is light. The tap is turned by holding and rotating the chuck. the idea seems to work.

Paul