Sandy's Workbench 7mm Scale

[N15class]

A lot of work on a little chassis but well worth the effort. Hope it does not put anyone off getteing the lovely little loco. Is the time spent anywhere close to the time need to scratch build a new one?

 

It always amazes me the number of time I hear someone cannot do a kit as they do not have or can't afford the jigs for setting the axles. Then look at you if you have two heads when you say they are not needed, they just make it easier, and there are ways to do it without them. I think I must be getting to the point now where at least half of my locos have been done with my JPL jig.

Edited February 17, 2013 by N15class

[Sandy Harper]

Hi Peter

The 'adjustments' to the chassis would take very little time to complete if you were retaining the fixed chassis, but of course I have to make it more difficult than it really needs to be! But that is just me!!

 

This is a very easy kit to put together and you end up with a 'loco', without the detailing, in a very short space of time. I have probably spent more time photographing and writing this than I have actually building!

 

I have probably used these lengths of 3/16th brass bar more than my chassis jig, as they are very useful for all sorts of things in the bending department!

 

Regards

Sandy

[Rob Pulham]

Hi Sandy, were you at the Bolton show earlier today? I ask as I thought I saw you by the guild stand but I was just on my way out the door and couldn't be certain it was you.

Edited February 17, 2013 by Rob Pulham

[Sandy Harper]

Well spotted Rob, sorry I did not see you. Got there about 11.45 and didn't stop talking until I left about 2.30. Even managed to spend a spell on a demo table to give Nigel Smith and his son a lunch break. Succumbed to a battery powered diesel outline loco in 16mm scale. Roll on the summer!!

 

Excellent show with some super layouts that I had never seen before. Oh, and the pie was good too!!

 

Sandy

[Sandy Harper]

Next little job was to put the Branchlines gearbox together. It pays to spend a little time with some sharp needle files to remove all the cusp edges and get the whole box to fit perfectly together. Again, getting it square, and keeping it square, is the secret to a sweet running gearbox.

 

Reaming out the bearing holes with a tapered reamer, slowly and carefully!

 

 

 

Here the 3/16th brass bar comes in useful again  to ensure the bearings are fitted square. Note that one bearing is fitted with the 'top hat rim' on the outside and the other on the inside of the box.

 

 

The gear box being trial fitted on the front axle. This may not be the final location as I will need to see how much clearance there is once the bonnet is fitted.

 

 

Regards

Sandy

Edited February 17, 2013 by Sandy Harper

[Sandy Harper]

As I stated earlier, I will be using split axle pickup on this loco. The first job is to fit the Perspex spacers to the underneath of the present brass spacers. I first used Araldite to glue the Perspex to the brass. I will then drill and tap through the brass and the perspex and screw them with countersunk screws. The final job will be to cut the brass spacer to separate the two chassis sides electrically.

 

This photo shows the spacers in position and clamped, awaiting the glue to dry

 

 

In the mean time I started on the footplate

 

This is the footplate and two buffer beams being built. Again making sure all is square.

 

 

6BA nuts added to the top of the footplate to fix the chassis

 

 

Chassis bolted to the footplate

 

 

 

The next job is to fit the dummy side frames to the footplate. There is a half etched line to assist you with the alignment but the etches are too long and need to be trimmed. I marked the length needed and then carefully removed the excess in small amounts with the tin-mans shears before finishing off with a file to get a neat fit.

 

 

The footplate valance does not have an etched line to help with location but it is a straightforward job to clamp them in position with spring clamps and solder. They are also way too long and will need trimming.

 

 

Regards

Sandy

[Sandy Harper]

Having got most of the undercarriage out of the way I have started on the superstructure.

 

The 'bonnet' is a very nice resin casting.

 

 

However, here is the first problem! The surrounds of the etch windows on the cab front are either etched too low or, the casting is too high!. There should be space between the bottom of the window surround and the top of the bonnet.

 

 

The cab front and sides are a single etch and need to be folded 90 degrees so that there is a 1.5mm gap between the side sheets and the edge of the footplate. There is very little to give the builder a clue as to where the radius bend should locate so I suggest a lot of measuring and marking out to try and locate the position before finally attempting the bend.

 

 

Having successfully made the cab sheet bends I then had to do the same for the rear of the cab. Again take your time to get them both the same.

 

 

 

The etched 'grills' leave a bit to be desired but should look OK under a layer of paint and grime!!

 

 

And finally for this session I added the cab cutout beading.

 

 

Regards

Sandy

[asa]

Looking good Sandy,I now have a decision to make,one of these or the C15 I originaly fancied.

[jazz]

Hi Sandy. Just had a read through the Sentinal build and I too, rarely use my axle jigs. Making quick and efficient use of a few 3/16" bars. The only time I use the axle jigs is on some manufacturers split coupling rods to check against the chassis bearings.

 

One thing I don't do is use tapered reamers on the axle bearings. I prefer 3/16" parallel reamers.

 

Nice build. Regards Ken 

[Barnaby]

Hello Jazz

Would it not be ok to use tapers in thin sheet as the taper would be minimal of course if used with sheet thicknesses of say 1mm up it might become relevant.

 

My main and limited use with tapers is they are variable so I can creep up on widening a hole.  They allow me to tackle a lot of different sized holes not requiring me to have several fixed sized Parallel reamers.

I'm sure I seen some where a variable or is it expandable parallel reamer but I'd probably stick with my tapered one.

 

Cheers

[Sandy Harper]

Thanks Ken

I totally agree with you about the reamers. The photo of me using the tapered reamer was on the thin  N/s of the gear box hole where the brass bearing fits into, and not the bearing itself. For that I use a parallel reamer.

 

Nice Duchess by the way.

 

Best regards

Sandy

[jazz]

Thanks Sandy, I thought it was the bushes you were talking about reaming with a taper.

 

 

Barnaby, Perfectly fine using a taper reamer on thin materials, I do that all the time. As I just said to Sandy, (reading the thread a bit quick, I thought it was the bush being reamed not the hole for the bush.) I'll have to slow down a bit before putting the jaws into gear.

[Sandy Harper]

Don't worry about it, I do the same my self. Too much to read and not enough time to read it!!!!

 

Sandy

[georgeT]

Hi Sandy,   Look's to be going together very nicely, alway's fancied one of these..

 

George..

[N15class]

Hi Sandy. Just had a read through the Sentinal build and I too, rarely use my axle jigs. Making quick and efficient use of a few 3/16" bars. The only time I use the axle jigs is on some manufacturers split coupling rods to check against the chassis bearings.

 

One thing I don't do is use tapered reamers on the axle bearings. I prefer 3/16" parallel reamers.

 

Nice build. Regards Ken 

I only use the parrallel reamers. for bearing I have a 190 thou one which is ideal on the odd over size axles

[Sandy Harper]

I only use the parallel reamers. for bearing I have a 190 thou one which is ideal on the odd over size axles

Hi Peter

I often find that a 3/16 parallel reamer won't open up an axle hole in a brass bearing enough to take a Slaters axle. I think this is due to Slaters using different batches of stock steel bar for their axles.. The Guild TIO, Bob Alderman, recommends using a 4.8mm reamer as that will give a running clearance. They are a bit hard to get hold of and not cheap!!! Alternatively I spin the axle up in the lathe and use fine wet & dry to take off a few microns to make it fit!!

 

Thanks George for your kind comments. I hope I can do it justice!

 

Regards

Sandy

Edited February 22, 2013 by Sandy Harper

[ozzyo]

Hello Sandy,

 

I use a 4.8mm reamer for the axle bearings as well, have a look on ebay you can normally get them for about £6.00. For the hight of the body I think that I'd remove it from the resin casting. To do this all I'd do is to stick some wet'n'dry to a length of flat wood and rub the body along it until you get it to the right hight. Doing it this way you have a better chance of keeping the base flat.

 

Nice looking little beast.

 

OzzyO.

[Sandy Harper]

Hello Sandy,

 

I use a 4.8mm reamer for the axle bearings as well, have a look on ebay you can normally get them for about £6.00. For the hight of the body I think that I'd remove it from the resin casting. To do this all I'd do is to stick some wet'n'dry to a length of flat wood and rub the body along it until you get it to the right hight. Doing it this way you have a better chance of keeping the base flat.

 

Nice looking little beast.

 

OzzyO.

Yep, that was my plan.

Sandy

[Barnaby]

While I've been thinking about wiring up the motor in my refurbished 22 you've nearly finished another model and I'm still only at the thinking stage.

 

I think I need to take a little piece of a page out of your book.

Incredible work Sandy.

 

Cheers

Edited February 22, 2013 by Barnaby

[Sandy Harper]

The buffer beams are large lumps of cast white metal, great for additional weight! Because they are so thick the buffer tails are completly encased within the beam and once they are attached to the loco you cannot get at the rear of the buffer.Make sure you use loctite or similar to prevent the nut coming loose at some time in the future.

 

 

The rear beam is not quite as thick but if you want the buffers to spring, then you need to drill a couple of clearance holes in the rear of the footplate. Still need to secure the nuts though.

 

 

 

 

Next I had a go at the roof. Not easy this. Take your time and bend a little at a time checking as you go with the cab profile. I still have some work to do yet. THe cabs of these locos must hae become very hot and uncomfortable for them to need such large roof vents!

 

 

 

The discrepancy between the 'Bonnet' and cab front has been resolved by taking down the height of the resin bonnett on a peice of wet and dry on a flat suface.

 

[asa]

Looking great Sandy.

[Mike Boucher]

Hello Jazz

Would it not be ok to use tapers in thin sheet as the taper would be minimal of course if used with sheet thicknesses of say 1mm up it might become relevant.

 

My main and limited use with tapers is they are variable so I can creep up on widening a hole.  They allow me to tackle a lot of different sized holes not requiring me to have several fixed sized Parallel reamers.

I'm sure I seen some where a variable or is it expandable parallel reamer but I'd probably stick with my tapered one.

 

Cheers

 

There are expandable parallel reamers, my father has a drawer full of them in his shop.  There's a small nut at the end, that when you turn it, it expands the flutes.  With care, you can adjust the diameter in some very fine increments.

 

Two problems

 

1) the smallest size I can find is 9/32, which is too big for our purpose.

2) They're also significantly more expensive than the 4.8mm reamers.

 

If you want to see the 9/32, look at

 

http://www1.mscdirect.com/cgi/NNSRIT2?PMAKA=72510183&PMPXNO=2053394&cm_re=ItemDetail-_-ResultListing-_-SearchResults

 

Be sitting down before you look at the price!

[John K]

Hi Sandy,

I apologise if I missed it, but how did you solve the window etch vs. bonnet height problem?

Did you take a mill or two off the bottom of the casting?

Best,

John

[Sandy Harper]

Hi John,

 

Yes, the resin is quite soft and it was an easy job to stroke it gently accross a peice of wet and dry (about 120, I think) to remove the unwanted resin. If you use a finer grade it clogs up too easily. Take your time and keep checking the fit. The rough surface that you end up with on the bottom of the casting also helps with getting a good grip for the glue.

 

See you on Saturday.

Regards

Sandy

[Sandy Harper]

Back to a bit more detailing now.

 

The springs, spring hangers and axle boxes all come as seperate brass castings and need to be soldered together. (There is also another small item that fits between the axle box and the left hand spring hanger which I have no idea what its for!)

 

Looking at a photograph, sorry not that clear as it came of the internet, the above mentioned item always appears be to be attached to the spring hanger to the left of the axle box.

 

 

However, the instructions state the opposite!!

 

 

 

I went with the photograph, and here are the four spring/axlebox units ready to be installed. To put them together you need three, no four hands, so a jig was made up from scrap timber and some pannel pins. By the time I got enough heat into the castings, to get them to solder together, the scrap wood burst into flame on a number of occassions, so I only had the charred remains left at the end of the exercise. Sorry, no photo!

 

 

The units now soldered to the outer chassis frame

 

 

Regards

Sandy