GWR Steam Railmotor Chassis

[Le Corbusier]

Maybe some kind bod on here with a pillar drill could drill you the required holes in an off-cut and pop it in the post? My Dremel solution is a bit too Heath Robinson for me to be comfortable doing it for someone else

[CornCrake]

Tim, thanks for the encouragement. You managed to give me a nudge in the right direction.
1st attempt, using a piece of steel strip failed when I broke the 0.70mm drill when almost through the second hole, but anyway the holes were not accurately 2.60mm apart.
I then had a brainwave for getting the holes the right distance apart. What did I have that had holes 2.60mm apart?
Or to put in another way a scale 8" apart.
A Bill Bedford handrail jig of course.
So the 2nd attempt into a sheet of Tufnol was better, using an Archimedes hand drill and the BB jig, managed to get the holes accurately spaced, well on one side anyway, but of course that meant holes were not vertical.
Am now halfway though 3rd attempt. This time I have managed to get two 0.70mm pilot holes in a brass etch offcut, using the Archimedes drill, but will now use that as a jig to try on the Tufnol sheet again, but this time with a dremel in a home made stand that I hope will give vertical holes.
Steve

[Armchair Modeller]

Rather than try drilling accurate holes in the wheels, you could make them slightly oversize. Then make a jig to hold the crankpin upright, the correct distance from the axle and use epoxy to fix the crankpin in place. You only need 2 accurate holes then - both in the jig.

[Will L]

The key element here is that the holes are vertical and the resulting jig is a good fit on the axle hole and the drill, the exact distance apart isn't a big issue. The wheels should end up all the same and you'll never detect any minor departure from 2.6mm.

I quite like our sedentary friends idea and the theory behind it, although I'm not sure I can entirely see how the assembly process would work out in practice

[Philip Hall]

If you don’t have a drill press, only a hand drill, a dodge I saw once (I think by Tony East in a very old Model Railway Constructor) used two small mirrors at right angles to one another, on the far side of the drill to the user. Any variation from the vertical can be seen in one mirror or the other and corrected.

Philip

[Le Corbusier]

Hi Tim,
Thanks for your suggestion.
I will give it a try, but without a pillar drill don't hold out much hope in getting the holes vertical/parallel.
I've also found this suggestion:- https://www.scalefour.org/forum/viewtopic.php?f=20&t=2019&start=50#p18358
The required crankpin throw is 8" which equates to 2.6mm, will have to see how accurately I can measure & mark up.
Steve

Steve,

The link you give here and its use of the Gibson crankpin bearing might offer a nice and simple upgrade on my Heath Robinson Approach. A larger and less accurate hole for the crankpin could be drilled in the jig (made slightly over size using a broach) Then the bearing could be soldered in using the lip to ensure it sits square and vertical in the jig. The axle location could be managed in a similar manner using an 1/8th top hat bearing. In theory I think this should remove the issues of not having an accurate pillar drill. .... I am assuming here that the crankpin bearing supplies the necessary fit to guide the drill bit used for drilling the pilot hole in the wheel. I shall definitely try Philip's ruse with the mirrors next time as an extra safe guard.

[Jeremy Suter]

To Get 2.6mm from the Centre of the Axle.

Would not the simple answer be.

Mark the centre line of the crank.
Then put a 1/8th rod through the Axle hole so that it protrudes slightly onto the front.
Put a bearing on it with a notch of the correct depth.
Then put the notch over the centre line and drill in the gap

[Le Corbusier]

To Get 2.6mm from the Centre of the Axle.
Mark the centre line of the crank.
Then put a 1/8th rod through the Axle hole so that it protrudes slightly onto the front.
Put a bearing on it with a notch of the correct depth.
Then put the notch over the centre line and drill in the gap

I can see how that will locate the position to drill. How does it help to ensure that you drill perpendicular in the absence of a pillar drill?

[CornCrake]

I have managed to make a jig in Tufnol with a 1/8" hole for the axle and a 0.70mm hole at the correct spacing for the crankpin, but unfortunately the holes are not vertical, the root cause being the alignment of my mini drill in the cradle of my home made stand.
However it has made me realise that even if I did manage to get the holes vertical there would be a catch 22 as I need to position a peg to hold the wheel in the correct radial position over the jig's crank pin hole, so I need a wheel with the crank pin hole already drilled...
The solution suggested by Jeremy with the notch in a bearing rather than a hole in my jig would allow me to see the correct alignment, once I have mastered the vertical drilling, which I think means acquiring a proper mini-drill press.
I have my eyes on this Katsu 100080 one https://www.aimtools.co.uk/collections/power-tools/products/20-4 which appears to have a chuck capable of accepting 0.60mm to 6.5mm drills.
Thanks for all the suggestions so far.

[Le Corbusier]

I would also be very interested to peoples thoughts on pillar drills. I would have thought the degree of play in the chuck is pretty critical given the tolerances we work to? Also .... presumably a milling machine would allow accurate drilling plus milling ... so might not that be the more cost effective purchase. I suppose the question is at what point does paying less become counter productive?

[Jeremy Suter]

Hi Tim
Although I do have all the machine tools to drill the holes in wheels for crankpins etc. I tend to do all small drilling by hand. I do have a watchmakers stake set which keeps the drill perpendicular.

The stake is fitted with a .75mm drill with a spot of super glue to hold it in.

Lots of other drills, I don't tend to change the drill bits I just sharpen them up again when they snap on a carborundum stone. The one with long rod is set with a .3mm drill I tend to use it horizontally with the other end under my arm.

This drill is .45mm sharpened into a lance and is still used to drill up to 1mm thick nickel silver sheet, now the twist has gone its actually a bit stronger it is set in a heavy pin chuck with a ball race handle generally used for drilling the rivet holes when pattern making.

Looking round the rest of the workshop I have a Cobra Vertical Milling machine fitted with a rotary table. A cheep metal workers pillar drill which I rarely use, I find there is too much rattle for what we are doing.

Looking at the corner there is a Pantograph milling machine. This machine was the best investment I ever made it has machined all the 51L wagon kits I designed and some of David Geens . Over 50 locos , lost count haw many loco frames and other parts. There is a unknown make watchmakers lathe, I usually use this only for making Buffers or Re-profileing Wheels.

The large lathe is a Hobbymat and the little one is a Boley watchmakers. I use both these two for making Loco fittings. Chimneys Domes etc, mostly.They are also used as milling machines, as sometimes its difficult to hold things in the big milling machine.

After all that. I am very tempted with the small pillar drill for smaller jobs.

[JackBlack]

Looking on eBay I think it's cheaper to buy a brand new lathe than an original watchmakers staking set!

[Horsetan]

Looking on eBay I think it's cheaper to buy a brand new lathe than an original watchmakers staking set!

Two-and-a-half grand

[Philip Hall]

The Katsu looks a nice little machine. I went for the small Proxxon many years ago because the Rohm chuck that was supplied as an accessory took drills down to 0.3mm. It rattles a bit (more than a bit if you leave it going too long) but doesn’t seem to have any play in the bearings and the survival rate of such small drills is good.

Philip

[Le Corbusier]

https://www.ebay.co.uk/itm/Hobbymat-Universal-BFE65-Lathe-And-Milling-Machine/362426348299?_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D52543%26meid%3D37fc36c7bbdc416185e3b3d882669d98%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D263927001400%26itm%3D362426348299&_trksid=p2047675.c100009.m1982

[Guy Rixon]

Comparing the prices for those two lathes, you have to ask yourself what accessories are included in the two packages. All the new lathes I've seen for sale come in two packages, with "a lathe" being massively cheaper than "a lathe with enough bits that you can actually use it". Not that I personally know what accessories would be needed, mind.

[Jeremy Suter]

I am now making up another 15 chassis kits to take to Scaleforum.


The Underframe etch production tool has been made and one sheet run off it.

All I need to complete the Underframe kit are some Buffer heads to fit my shanks. I will make the heads and have them lost wax cast after scaleforum.

Then I will do the online instructions.

[Horsetan]

....The Underframe etch production tool has been made and one sheet run off it.

All I need to complete the Underframe kit are some Buffer heads to fit my shanks. I will make the heads and have them lost wax cast after scaleforum.

Then I will do the online instructions.
IMG_4523.JPG

Is this for the 57ft or 70ft

[Jeremy Suter]

Is this for the 57ft or 70ft

Hi Ivan
I am doing the Gloucester built 59' diagram Q and Q1 to start with. I will move onto a longer ones later.

[Horsetan]

Is this for the 57ft or 70ft

Hi Ivan
I am doing the Gloucester built 59' diagram Q and Q1 to start with. I will move onto a longer ones later.

Aha. Good to know.

[GWSGMember]

Looking forward to getting these to complete the underworks of my Railmotors.

Where will you be at Sclaeforum - on the Stores counter?
Would love to chat about this project.

Picking up some wheels from Alan Gibson at the show.

Ken

[CornCrake]

Hi Jeremy, thanks for a glimpse of the railmotor birthplace, a fascinating insight into the range of tools available to you...
Steve

[CornCrake]

Jeremy, Thanks for the time you spent chatting at Scaleforum. It was good to see your video of the railmotor circulating on the test track.
I can report that I have made four steps forward:-
The Katsu mini pillar drill arrived last week and appears to be good value for the money.
1) I can now drill vertical holes.
2) I have managed to drill the crankpin holes
3) Countersunk the crankpin hole on the back of the wheel
4) Managed to screw in a crankpin
One step back:-
-1) Attempted test fit of wheel into my GW Models quartering jig, only to find that it seems the jig cannot cater for such a short crankpin throw.

I have found an instruction leaflet for a Hamblngs quartering jig so now just have to search all my boxes for the actual jig & hope that it can cater for 8" crankpin throw.

However I am pleased to have achieved orthogonal crankpins at last!
Steve

[Jeremy Suter]

I test ran the Railmotor Chassis and under frame at Scaleforum and can be seen at

https://youtu.be/u0RNgk_JB5o

[Horsetan]

I teat ran the Railmotor Chassis and under frame at Scaleforum and can be seen at

https://youtu.be/u0RNgk_JB5o