Class 22 Diesel (next project)

Back to the buffers I went with setting up in the 4 jaw to get the basic shape (Daves idea, thanks Dave) and it worked well. I did start out using the parting tool which would probably have been ok but I chickened out worrying about a grab which would wreck the buffer. I went with a standard tool and 10 thou cuts, didnt take long as it is only a thin face to machine. The secret was cutting one face and then turning the buffer through 180 and getting it pretty much spot on otherwise you would end up with a weird shape. Just some hand shaping now on the ends which is not too much.

No visual just sound, I am giving a budget priced sound system a try for the loco. Its a third of the price of the top end systems which can cover a particular class of loco. It comes complete with a speaker and is ready to go, no setting up other than the volume which is adjustable. The two tone horn is not correct for a class 22 but I can live with that, I rather like the engine start up and the run down, sounds quite good I think.

It sounds better than it does through the camera and I have also found that the sound quality improves if the speaker is housed and not free standing in the open.

You may need to adjust your volume up or down.

Edited By Ron Laden on 14/11/2019 14:09:49

Edited By Ron Laden on 14/11/2019 14:13:11

Sound system as mentioned above

Still working away on the chassis so I thought I had better get the buffers finished. I was going to make them one piece but went for a separate base plate in the end. The fixing bolts are dummies (5BA) and not even threaded, I drilled a close fitting hole and fixed them with 638, the buffer assy is fitted to the chassis with a single M6 cap head.

I started a bit of light weathering on one of them and will do more when I weather the buffer plate. I am quite pleased with them though they are not perfect but the best I can make of them.

Boring a clearance hole in the two chassis top plates (3mm steel) to allow a 17mm socket access for adjusting the bogie pivot bolt, the plates only just fitted mounted diagonally across the table which allowed a clamp on each corner.

The picture also shows the bogie plates and the pivot bolt, I just kept it simple and shortened a M10 bolt leaving enough plain shoulder to run through both the bogie and chassis plate, the chassis plate is a copy of the bogie plate. I have also produced a 2mm thick x 35mm dia thrust washer but I am going to remake those increasing to 55mm diameter. I have also gone simple by using a nyloc nut to hold the pivot in place, once adjusted and at the moment I am thinking 0.50mm end float the nyloc should hold that position and not work loose.

On one of the plates you may be able to make out a pair of M5 hex heads either side of the M10 head, these are to prevent the bolt from rotating when adjusting the nyloc. When the motors are assembled into the bogie frame there is no access to the bolt head with a spanner or socket as the head is almost hidden. I did think about having the head tack welded or thread the plate and fix with 638 but that would mean losing the plain shoulder and having to make a sleeve/bush. So again I went simple and fitted the M5 Hex heads, when the bogie is assembled I can just get a thin screwdriver between the motors to push the bolt head up between the M5,s until the nyloc pulls it up to the plate.

Not too far away from having a rolling chassis.

Edited By Ron Laden on 28/11/2019 10:09:04

At long last I have a rolling chassis, more detail to add to the sides and ends but that can come later as I want to make a start on the body.

Still thinking about the best approach for the build of the body, I have considered carving a blue foam plug and laying up a glass shell with laminating epoxy. I have used the method a few times in the past on R/C aircraft but in a small workshop the thought of being knee deep in foam shavings doesnt appeal much.

I built the shunter body from a mix of 6mm MDF, 1mm, 2mm and 3mm ply, ABS and alu sheet and it worked quite well so that is an option but the class 22 body is twice the length so it would mean more in the way of framing.

Anyway pleased the main chassis and bogies are complete.

I have the loco body, well not really but I have my original sketch which I offered up for an idea of sizes and how it looks, the sketch is short lengthways by 35mm so needs to grow a tad.

I have decided to go with the MDF, PLY, ABS etc as I did with the 0-4-0 shunter, I,m quite happy working with those materials, the loco length is 48 inches buffer to buffer.

The body main side panels will be 6mm MDF and you can see from the sketch there are a good number of doors and vent panels. I dont fancy cutting all those out and weakening the panels so I am thinking of facing the MDF with 1.5 mm Birch ply and cutting the apertures out of the ply, it will cut well with a good Stanley blade and a steel rule. I can then make and fit the doors/vents into the recesses and only cut through the MDF for the windows. Also a bonus with the Birch ply is that it is easier to achieve a good surface finish plus its a tougher skin and doesnt suffer dings as easily as MDF.

The curved roof will be a skin of 1 mm Birch ply built on a framework, at the moment I plan on having the roof lift off for access.

Anyway thats the plan so will see how I get on with it.

The 6mm MDF body side panels will need some 3mm deep recesses and slots and for what I need to do it would be much easier if I can cut them on the mill. I know you can get away with cutting wood and the like with metal working cutters but I have not tried MDF and wonder what type of cutter I should be looking at bearing in mind that I only have 2500 rpm top speed.

I was thinking of trying a 2 or 3mm 2 flute uncoated HSS Al cutter which I would have to get in but before I do wondered if any of you guys have any thoughts on it.

I appreciate that wood cutting bits would be the way to go but they run at much higher speeds than I have available.

Thanks

Ron

Almost anything will cut MDF! I suggest either what you mention of perhaps better a wood router bit as big as will do the job. If the loco is going to run outside (I assume it will) then take great care to seal the MDF afterwards. At the moment I'm doing quite a lot of work with Valchromat which is like a very high spec MDF, harder/stronger/less toxic/a "solid surface". Also less wear on cutters. It can be used outdoors when properly sealed. I mill pockets etc in it using a 1/4" router cutter at 5000 rpm quite happily. Recommended if you can get some.

Ron you would be best with carbide as MDF is quite abrasive and will quickly wear the cutter. Either a 2-flute carbide milling cutter or router bit both run at top speed.

If you have not bought the MDF yet then get MR MDF (Moisture resistant) not so much for that property but it is almost twice the density of "standard" MDF so does not have such a fluffy edge when cut.

If you use MDF whether it is the standard or the MR stuff one thing you may find that any cut or routed edges will suck up paint like mad

I made a rocker motorbike and found that the best thing was to apply a coat of PVA glue on any edges this sealed them and made painting a lot easier.

If you need to produce small lines on the surface like I have done on this piece (see the door and bonnet detail) I used a 1.2mm router bit as used in a dolls house router set by Trend. If interested I will post a link to them

Edited By Derek Lane on 12/12/2019 16:16:05

Derek's suggestion of PVA is good - can apply over the whole surface to seal after milling. Thin down a bit first.

Another suggestion is a product sold by Ronseal for rotten wood. It's a resin dissolved in a volatile liquid that you splash on liberally with a brush and gets soaked up like water in the desert After a couple of hours it has set hard, gluing all the fibres together. May need a couple of applications with MDF, but should help waterproof it as well.

Thanks guys thats helpful.

Valchromat and the Ronseal looks interesting also the small router bits thanks for the links.

I would never have thought of MDF as abrasive just goes to show. I will get a 3mm 2 flute carbide from ARC, s premium range and give it a go. For convenience I buy 4ft x 2ft cut sheet I will see if I can find some MR MDF in cut sizes.

Must admit that I never bother to seal the edges of MDF just go straight on with Dulux Trade quick dry Primer/Undercoat, just off to get some more after lunch as I have 850kg of MR MDF to get painted for the current job.

If speed is important would it be helpful to use a cutter double the diameter then the cutting edge is running at twice the peripheral speed? Does it help to apply some sealer / binder to the cut line before cutting to help hold the edge together for a cleaner line?

850 kgs..? hells bells Jason watch your back.

I expect he's making a full-size version of Derek's half-track!

Don't worry Ron, I won't try and lift it all at once and with my brother having had a hernia op on Monday it's not my back I will be thinking of!

No not a half track, just making shelving to keep all of his engines on!!

I used to use an Evostik water based contact adhesive it came in a flat furniture polish sized tin, it came with a red plastic spreader which had a 50mm round of foam which made it very good for covering large areas at an even thickness.

I dont know if anyone is familiar with it but I suspect it has been discontinued as I cant find it anywhere, I used to buy it at the DIY stores but none of them seem to carry it any more. I would be interested if anyone knows of an equivalent product that comes in smaller sized tins, I know that there is trade size tins of water based contact but that is way more than I would ever need or use.

Ron