Tim V's workbench - broad gauge tomfoolery

User avatar
45609
Posts: 180
Joined: Mon Jul 21, 2008 10:28 am

Re: Tim V's workbench

Postby 45609 » Sun Feb 06, 2011 10:19 pm

Hi Tim,

What is the origin of the collet attachment in your Unimat?

Cheers....Morgan

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Mon Feb 07, 2011 4:57 pm

Standard 8mm WW drawbar, it was sold as an accessory for the Unimat.
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Mon Feb 07, 2011 5:18 pm

Once the wheels were fixed on, I found that there was still a problem with poor running, I re-centred the coupling rods, using ideas from Chris Pendlenton's article in MRJ 200.

It now runs a lot better, there is a bit of roughness from the three pole motor, I might have a look to see if I can tune that out in the chip.
Tim V
Scalefour News Editor

User avatar
HowardGWR
Posts: 212
Joined: Fri Jul 25, 2008 10:42 am

Re: Tim V's workbench

Postby HowardGWR » Mon Feb 07, 2011 8:48 pm

On the copperclad spacers thanks for the reply Tim. I did try this on one attempt. I fixed the spacers on as per pick up type frame and then I soldered the gapped copperclad to the spacers and then cut through the spacers. Heart in mouth stuff but I got away with it. Nothing must come adrift after that though. Regards, Howard

Philip Hall
Posts: 1528
Joined: Mon Aug 10, 2009 7:49 pm

Re: Tim V's workbench

Postby Philip Hall » Tue Feb 08, 2011 5:19 pm

Tim V wrote:
there is a bit of roughness from the three pole motor


I've just looked at my 45XX chassis and it seems the motor is similar to that in the N. For that I have a replacement Mashima so it might be possible to slot one in if you have no luck with the tuning. I gather there may be problems, though, with getting the worm off and/or the motor shaft diameter.

Philip

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Tue Feb 08, 2011 6:19 pm

I'm pleased to say that by fiddling with CV9 - the pulse width modulation, as well as CV50 the motor type (Lenz mini silver), I was able to improve the noise from the motor.

All this work was done on a Sprog.

I don't know how DC people cope without this kind of fine tuning!
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Sat Feb 12, 2011 7:00 pm

I've been making split axles this afternoon.
IMG_0934.JPG
IMG_0934.JPG (114.32 KiB) Viewed 8391 times

The axles have been turned on the lathe, here I'm about to drill the bleed hole for the Araldite to squeeze out of.

The male halves were turned 2mm diameter, with the hole drilled 3/32" or 2.3mm. There is a spacer washer made from plastic.
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Sat Feb 12, 2011 7:53 pm

IMG_0935.JPG
IMG_0935.JPG (109.07 KiB) Viewed 8380 times

The axles have been thoroughly cleaned, including using a clean drill to remove any traces of swarf. A quick dip in an ultrasonic bath pepped them up. Eventually, they were placed in the jig seen here, held together with a 6mm nut and bolt. Plenty of trying them with a multimeter and ensuring they were 22.2mm overall length.

To keep them from sticking to the jig, I used Vaseline on the faces.

The jig was made on the Unimat.
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Sun Feb 13, 2011 4:34 pm

Unlike my last project engine, I'm using Gibson wheels on my current one.

Problems with Gibson wheels are well known, so we can approach them forewarned. The rims falling off is the main one, though recent batches of wheels are better.

First task is to pop the rims off, on these I easily pressed them out by hand. A certain Gordon Ashton used to pop rims off by putting the wheels into hot water, in this case it cracked the rim!

Once the rim is off, clean up any moulding pips off the centre, and any other flash. As I have a lathe, I've put the centres onto a mandrel, and run a tool over the outside, plus the front. Once all this is done, I'll use my favourite 10 minute epoxy to glue the rims back on.

Why all this fuss? Square round wheels are essential to good running.
IMG_0937.JPG
IMG_0937.JPG (119.13 KiB) Viewed 8332 times
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Tue Feb 22, 2011 5:19 pm

Starting on the crankpins now. First job, measure up what I want. No scale diagrams here, a sketch will do.
IMG_0948.JPG
IMG_0948.JPG (157.48 KiB) Viewed 8251 times
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Wed Feb 23, 2011 5:12 pm

Here I'm parting off the crankpin. These blighter's have a habit of falling off, never to be found.
IMG_0949.JPG
IMG_0949.JPG (85.78 KiB) Viewed 8194 times

I just poke a piece of wire into the hole, to keep hold of the turning before it falls off.
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Wed Feb 23, 2011 5:15 pm

Here, I've turned the crankpin round, to hold it on its running surface. I'm using a pin chuck. I've turned the outer face in this case, and that is a 14BA tap ready to thread the hole. This will NOT be under power of course.
IMG_0973.JPG
IMG_0973.JPG (84.43 KiB) Viewed 8196 times
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Wed Feb 23, 2011 7:35 pm

Those are the easy crankpins, what about the recessed ones I hear you say :?:
Well, they are made with a cone to match a small countersink, like this.
IMG_0976.JPG
IMG_0976.JPG (88.92 KiB) Viewed 8179 times

They have a slot filed across, so they can be tightened up. Here is one held in an ordinary pin vice.
IMG_0974.JPG
IMG_0974.JPG (69.58 KiB) Viewed 8179 times

The slot is made using this kind of file, this one came from Shesto's many years ago.
IMG_0975.JPG
IMG_0975.JPG (73.56 KiB) Viewed 8179 times
Tim V
Scalefour News Editor

User avatar
John Bateson
Posts: 706
Joined: Wed Jul 02, 2008 6:39 pm

Re: Tim V's workbench

Postby John Bateson » Fri Feb 25, 2011 2:07 pm

Tim - are your crankpins made from solid rod or are you using tubing.
John
Slaving away still on GCR stuff ...
Avoiding the soaps ...
https://www.greatcentralmodels.co.uk

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Fri Feb 25, 2011 4:05 pm

I use 1/8" solid rod, I couldn't guarantee the concentricity of the tube.

I make my own crankpins because it does guarantee that they are concentric, and they can be tightened up properly. My experience of bought in crankpins is that the hole is often oversized, leading to inconsistent throws.
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench wiper pickups

Postby Tim V » Fri Mar 04, 2011 9:45 pm

I don't get on with wiper pickups, I have very few locos with them.

This is a pannier chassis from the early 90s, from a standard Perseverance kit. It was failed at Southampton with dodgy pickups, something my split axle locos do not suffer from.
The starting point.
IMG_0985.JPG
IMG_0985.JPG (100.41 KiB) Viewed 7997 times

Out of interest, here is the top.
IMG_0986.JPG
IMG_0986.JPG (110.2 KiB) Viewed 7997 times

I have put new pickups on the front, but oh dear disaster strikes, the rear board has detached. I'd glued it on!
IMG_0987.JPG
IMG_0987.JPG (100.04 KiB) Viewed 7997 times

Here I have put a new board on, held on with a screw.
IMG_0988.JPG
IMG_0988.JPG (106.65 KiB) Viewed 7997 times
Tim V
Scalefour News Editor

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Fri Mar 04, 2011 9:50 pm

If I had my way, I'd scrap this chassis and put a proper split axle one on it.
Tim V
Scalefour News Editor

martin goodall
Posts: 1110
Joined: Fri Oct 02, 2009 6:20 pm

Re: Tim V's workbench

Postby martin goodall » Sat Mar 05, 2011 3:33 pm

Tim V wrote:If I had my way, I'd scrap this chassis and put a proper split axle one on it.


Every demonstration I have seen of locos with split frame/split axles has convinced me that this is an infinitely superior method of current collection.

The only reason I have never adopted it is that it clearly requires more time and effort to build that type of chassis, particularly when most kit chassis make no provision for a split frame, so that you would have to adapt it yourself (= more work). And then, of course, there is the bother of 'shorting out' plastic centred wheels so as to get the current from the tyre to the axle.

But my main reason for taking Tim up on this is the question of practicality in relation to gearboxes, suspension systems, etc. Just fitting a gearbox in between the wheel bearings can be a struggle sometimes. How do you also fit in the necessary insulation gap without the risk of something bridging that gap and shorting the whole thing out? (There is also the question of how you insulate a centrally mounted compensating beam, although that is probably easier to solve in practice.)

If someone can come up with an easy way round these problems, I would be a happy convert to split-frame current collection. Meanwhile, I remain a somewhat reluctant user of wiper pick-ups.

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Mon Mar 07, 2011 7:08 pm

Good point Martin.

The Highlevel site gives the width of their gearboxes, I've used the 54:1 usually. Some of the gearboxes are wider, I avoid those.
Left to right are
1. The wiper loco previously referred to, this has a Highlevel 54:1, plenty of room to put split axles,
2. A Highlevel 54:1 on split axles,
3. A Branchlines 50:1 (I think) on split axles, and finally
4. A Highlevel 54:1 on split axles. This is the project Comet prairie chassis from the workbench. Note that the split axle locos look a lot tidier :!:
IMG_0993.JPG
IMG_0993.JPG (144.16 KiB) Viewed 7887 times

A close up on one chassis, you can just make out the split in the axle, I've used green plastic as a spacer. Gearbox width 8mm, space between my favourite Brassmasters hornblocks, 13mm, so plenty of room. There is a way of making bearings so that wider boxes can be used, but that would need a sketch.
IMG_0994.JPG
IMG_0994.JPG (131.02 KiB) Viewed 7887 times


Following the success of recentreing the rods on the small prairie, I've looked at one of the Bachman panniers, turns out although the rods alignment very well, the rivet joining front and back was loose, so I'm making a new pivot to hold the rods together. I'm using standard 1/8" alignment jigs, held lightly on with clamps.
IMG_0992.JPG
IMG_0992.JPG (90.58 KiB) Viewed 7887 times
Tim V
Scalefour News Editor

User avatar
David Thorpe
Posts: 939
Joined: Tue Oct 21, 2008 11:13 pm

Re: Tim V's workbench

Postby David Thorpe » Mon Mar 07, 2011 8:17 pm

Am I right in thinking that you make your own split axles?

DT

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Mon Mar 07, 2011 9:52 pm

Yes, shown further up the page.
Tim V
Scalefour News Editor

User avatar
David Thorpe
Posts: 939
Joined: Tue Oct 21, 2008 11:13 pm

Re: Tim V's workbench

Postby David Thorpe » Tue Mar 08, 2011 3:21 pm

Tim V wrote:Yes, shown further up the page.

Sorry, missed that - I was away and when i came back i must have overlooked it.

I'd love to use split axles, but am put off by the unavailability of suitable axles for people who for whatever reason are unable to make their own. I know that Branchlines do them, and the EMGS sells completed split axles, but all are gapped in one place only while if you're going to use them with a gearbox, or indeed any kind of drive, they need to be gapped in two places, and you really need to be able to choose exactly where these places are. Bill bedford produced some good ones, but has discontinued them. Don't suppose you'd like to produce some commercially so that we split axle wannabes can give it a go? :?: :?:

DT

User avatar
Tim V
Posts: 2436
Joined: Tue Jul 29, 2008 4:40 pm

Re: Tim V's workbench

Postby Tim V » Tue Mar 08, 2011 5:47 pm

That is a good point, but I'm sure there is someone local who could knock them up, I'm not set up to produce large numbers of split axles.

I actually only split mine on one side, even on the gearbox axle, I haven't looked at the commercial ones. Perhaps you need to lobby the manufacturers?

By the way the lathe was the best investment I made in the hobby - other than joining the Scalefour Society! And I think my 30 years membership equates to the cost of a lathe.....
Tim V
Scalefour News Editor

User avatar
steamraiser
Posts: 460
Joined: Thu Dec 31, 2009 4:49 pm

Re: Tim V's workbench

Postby steamraiser » Tue Mar 08, 2011 5:53 pm

Scalefour Stores also carry split axles. These give you the option of a three part axle that gives an isolated middle section.

Gordon A
Bristol

martin goodall
Posts: 1110
Joined: Fri Oct 02, 2009 6:20 pm

Re: Tim V's workbench

Postby martin goodall » Tue Mar 08, 2011 6:29 pm

While on the subject of split axles, my favourite driving wheels (in fact the only wheels I like to use) are Ultrascale. But they have a fairly substantial plastic boss on the back of the wheel. Has anyone used these wheels on a split-frame loco? If so, did you cut off the boss behind the wheel to fit the 'shorting' strip/wire? If not, how would you propoose that these wheels should be treated if/when adapting them for split-frame operation?


Return to “Tim V”

Who is online

Users browsing this forum: No registered users and 1 guest