Author Topic: 31/2" Tich  (Read 1077 times)

Offline kvom

  • Full Member
  • ****
  • Posts: 2294
Re: 31/2" Tich
« Reply #15 on: April 19, 2020, 06:02:54 PM »
Interesting to see a milling attachment used on the lathe, likely the way LSBC did it.  I know that the Westbury paddle engine I built was done that way in the 50s.

Offline GWRdriver

  • Full Member
  • ****
  • Posts: 139
  • Tennessee USA
Re: 31/2" Tich
« Reply #16 on: April 19, 2020, 06:10:28 PM »
I built a 71/4 inch gauge version of TICH many years ago, [snip] Perhaps others have a view on this. - Trevorc
I will eventually get to my point and in the meantime my apologies for semi-hijacking samc88's thread, which I'm also following with interest.

I have a 2X (7.5"ga) TICH under construction but I changed a number of frame dimensions to accommodate larger drivers so the original valve gear drawing (adapted from LBSC's 3.5"ga by Harry or Chas Kennion) won't apply to my chassis.  I have to do my gear from scratch, and it's giving me fits, but in all fairness to the gear I've yet to sit down with a saucer of biscuits and a full pot a' and wrestle it into submission.

I've also learned that valve gears are a particular source of errors, innocently made perhaps, but never corrected despite being widely found.  My first mentor, a meticulous builder, embarked upon an LBSC MABEL only to find a major error in the rocking linkage location which required remaking most of the valve train.  He was not pleased, and I've come to view valve gear designs through very squinty eyes.   :Lol:

Quote
It would therefore be wise to make your own check on valve gear dimensions.
If you're not already familiar with them, the Dockstader valve gear programs are excellent for just that.  Dockstader is not a "design" program per se, although it can certainly be a valuable tool in helping develop your own gear design or adapting one, rather it's intended to be a testing tool, which will give you an animated picture and report of the events of a given gear design.

Running the basic TICH gear through Dockstader won't necessarily expose "errors", but it will show how the gear as-designed behaves and will tell you where improvements in events can be made, if you want to make them.
Cheers,
Harry

Offline samc88

  • Full Member
  • ****
  • Posts: 60
Re: 31/2" Tich
« Reply #17 on: April 19, 2020, 09:06:20 PM »
Thanks for the information on the valve gear. Shall definitely bear that in mind when I come round to it, I think I'll be doing the Walschearts mechanism as to me it looks better than the slip eccentric. Don't consider it hijacking the thread, it's all good to know!

Kvom, yes the vertical slide is handy but when I move to my new place a small mill is definitely on the cards

Sent from my G3121 using Tapatalk


Offline samc88

  • Full Member
  • ****
  • Posts: 60
Re: 31/2" Tich
« Reply #18 on: April 19, 2020, 09:12:55 PM »
After playing around with the land rovers this morning pulling my brothers 90 forward in the garage with my 88 I set about on this for a bit more work

First off I drilled the brackets for 7BA bolts and did another assembly. I'm using hex heads rather than cheese head bolts as they just look better to me (also I already have some to hand)

Next I machined the axle box rebate to use as a gauge for opening out the hornblocks. This was an interesting thing to work out but got there in the end once I took the splash guard off, not the most rigid set up but with light cuts it worked well, just have to finish the corners by hand as I don't have a cutter long enough. Axle box is a snug fit so with some final fettling by hand it should all run smoothly.


Sent from my G3121 using Tapatalk


Offline samc88

  • Full Member
  • ****
  • Posts: 60
Re: 31/2" Tich
« Reply #19 on: April 20, 2020, 02:33:47 PM »
Finished off the hornblocks and bolted up the frames. Also machined the pump stay at both ends to be a nice fit between the frames

Sent from my G3121 using Tapatalk


Offline crueby

  • Full Member
  • *****
  • Posts: 10569
  • Rochester NY
Re: 31/2" Tich
« Reply #20 on: April 20, 2020, 04:22:45 PM »
Rolling right along!   :popcorn: :popcorn: :popcorn:

Offline samc88

  • Full Member
  • ****
  • Posts: 60
Re: 31/2" Tich
« Reply #21 on: April 23, 2020, 09:31:40 PM »
Not a great deal to report, been busy with other things but got the time today to square up the second pair of axle boxes ready for final machining to size and tidied up the workbench and toolbox

Sent from my G3121 using Tapatalk


Offline samc88

  • Full Member
  • ****
  • Posts: 60
Re: 31/2" Tich
« Reply #22 on: April 24, 2020, 07:33:22 PM »
Bit more axlebox progress, machined the sides of the second pair so they're a snug fit which is what I wanted, means I can finish them both to a nice fit now, only needs a couple of thou coming off the side to go up and down freely I think. Once that's done I'll machine the other faces. The frames are black as I had a bit left after I was painting my garden roller so just put a thin coat on to protect it a bit

Also shown is my milling set up and how I can accurately set my Z axis which is now going along the lathe bad rather than up and down on a conventional machine. I took a gear out of the change gear train at the headstock end so the leadscrew is free to rotate, I then lock the half nuts and wind the lead screw with a 10mm spanner which moves the carriage left and right (into or away from the cutter). Eventually I'll actually make a proper hand wheel for the lead screw

Sent from my G3121 using Tapatalk

Offline MJM460

  • Full Member
  • ****
  • Posts: 1103
  • Melbourne, Australia
Re: 31/2" Tich
« Reply #23 on: April 24, 2020, 11:53:31 PM »
Hi Sam, you are making great progress.

That is a very nice vertical slide for your lathe, I can see why it works so well.  I have not seen one like that before, perhaps I was not looking very hard.  Good idea on the lead screw too.  The one I bought had provision to rotate the slide and around an axis parallel to the lathe axis, which, while it might have had some extra functionality, made the support very flexible, so it did not work so well.  Nothing like the rigid mounting yours has.  Probably why I never found it very satisfactory.

MJM460


The more I learn, the more I find that I still have to learn!