16mm IDRIS

IDRIS DRAWING ERROR ... in part 4 of the series, at the bottom of page 872 is figure 16 ... there are 3 references to 7 BA threads ... these should read 6 BA ... the text alongside the drawing correctly reads 6 BA ... cannot blame the gremlins for this one ... my fault.

martin

Hi Martin. I had already worked that one out. I have 6 BA screws and they all fit as expected.
I will comment that this makes the crank pin bushes very thin. I may go up a bit on the ID of the bushes.

I'm wondering where the text went that was with the photo....

4 wheels started.

Boss is 16mm dia X 11mm long. may well reduce this later. It's 16mm cos I have a 16mm Collet.

I turned the boss taking ~ 2mm cuts down to 17mm dia then cleaned it all up. The myford was quite happy with this.
Parted them off at 7mm with a 2mm wide tool. It really didn't like that much.
The tool dug in several times during each cut. The clutch I fitted has proven most valuable.
Tried everything including regrinding the tool.

I'll put the boss into the Collet chuck to drill the hole and turn the tread. That should keep it all concentric.
What sort of angles do I need on the flange and tread ?

Morning Alex ... welcome back ... wow ! a 2 mm cut in steel is very impressive, I am pretty sure my small lathe would be struggling ... how far away from the chuck were you cutting when doing the parting-off ?

As regards the angles on the wheels ... I am not the worlds best expert on railway practices ... what I have found out varies with who I ask ... the angle between the tread and the flange is a bit bigger than 90 degrees ... the tread is not parallel, it is slightly coned by about 3 - 6 degrees ... the flange is not vertical, it is tipped inwards towards the middle of the track by 6 - 14 degrees, typically 10 degrees ... where the tread meets the flange is sometimes a sharp corner and sometimes a very small radius, about 0. 5 to 1mm ... the flange depth for 32 mm seems to be about 2 - 3 mm.

If all else fails, try and measure the commercial wheels you have bought ... hope this is some use.

martin

Hi Martin.

I cut off 100 mm of bar. That gave me enough for 4 wheels + the option of a 5th.
For the first 2 I used a steady + the centre. The 2nd pair I ditched the centre.

Cleaned the lathe tonight. The parting issues were probably caused by the lash in the cross slide getting sucked in.
I'll add in a bit of friction on the slide locks next time....

John. Will wonder over to that site and have a look.

Thanks

Alex ... just a P.S. to my words above ... some of the commercial wheels I bought a few years ago only had a small flange ... I did not realise at the time ... the depth was less than 1. 5 mm ( actually 0. 055 inches ) ... the wagon with those wheels would occasionally leap skywards passing over a point ... problem ceased when I managed to re-cut the flange a bit deeper ...maybe 2 mm is a decent minimum depth ?

I have just been given a long list of jobs from SWMBO, so I will be busy for a few days ... have to turn the lathe off for a while !!! horror !!! back soon.

martin

Wheels complete. Just need to drill and tap for the grub screws.

You may have to forgive me this one.
Fig 17, Page 873.
The drawing for the eccentric says:
Throw 0.236
Center offset half of this = 0.118
That's fine.
I get a bit of round bar Offset it by 0.118.

What size round bar do I start with ? ( or what size is the lobe )

0.625" - 5/8"

There is a clue written just under the big bold "Eccentric" print

DOH!
Thankyou Jason

Morning Alex ... like the look of the 4 wheels ... I do not know if this is any use to you ... the commercial wheels I bought had a thickness of approx. 0. 474 inches ( 12. 03 mm ? ) ... they were not all exactly the same ... I varied the size of the bearing bushes to match the individual wheels ... you may have to do something similar ... I positioned the wheels at the correct distance apart and worked backwards to get the width of the final drive gear ( fig 5 page 590, fig 17 and 18 page 873 

martin

Spoke to the Boiler man today. CSME had a members open day.
He is happy with the general construction and soldering. As expected commented that the 2 top bushes were not up to standard.
I need to re flux them and get the solder that is on them to flow. At that point the boiler should be fine.
Spoke in detail and it's obvious to me that my Hearth is not good enough. I should have enough heat with the tools I have but the heat is escaping.

The frame also got favourable comments. Picked up some tips on the motion bars. I need to make them on a jig.

Some great Models on display and running. Guy had his first run in a polly. The grin went full circle.

I now have smooth motion.
Centre Popped a Jig through the frame rails. Ground up a bit of 1/4" silver steel to a point.
Soft soldered the rods (to the jig as well most of the time). Took a few goes to get them right.
Making Bushes to go over 6BA screws (2.6mm ID / 1/8" OD) was not going to be easy. I also think the crush factor as we do up the screws may be rather high.
Drilled the motion rods 4mm and made some shouldered screws.
8mm OD Head. 4 mm shank for the bushes to run in 6BA Thread for the crank arms.

Motion was a tad sticky so drilled the bushes to 4.2mm and all is good.

Wheels all line up but I don't have a suitable track or place to put the track.
The CSME (Chelmsford society of Model engineers) Track will allow me to run between gauges if I shorten the axle bushes.

Alex ... a question about your letter above ... does this mean you are using the rails for 2 1/2 and 3 1/2 inch tracks or does it mean you are using the rails for 3 1/2 and 5 inch tracks please ?? if you eventually get your own 32 mm track does it mean the bushes will need to be remade a different length ??

Does it mean you may need some new spacers to hold everything in place along the 2 axles ??

martin

Hi Martin.
The Chelmsford Track has 3 1/2", 5" and 7 1/4" Tracks.
None of these gauges are suitable - they are to wide.

My Thoughts are, with narrower Axle spacers I can move the wheels apart and run on the track between the 5" and 7 1/4" gauges.
I'm aware that running on these rails would be totally unsupported but briefly spoke to a member who has done just that.
I did intend to measure the actual gaps last weekend. I forgot to take a suitable measuring stick.

Maybe my ideas are crazy at times............

I need to go measure. Until I do that nothing is final....