Rebuilt Bulleid West Country 3D CAD designed & mft in 3.5 in

[andyhigham]

Up to a point the "black oxide" helps keep the "red oxide" at bay

[masahiraoka]

Roger, Kerrin and Andy

using heat to help the bending sounds like a good idea - i'll raise it with Andrew and Phil at our monthly project meeting due this week!

Personally I'm in favour of more tab and slot type detail to avoid the necessity of folding as much as possible



ciao Martyn

[Roger]

Jun 1, 2020 3:44:43 GMT masahiraoka said:

Roger, Kerrin and Andy

using heat to help the bending sounds like a good idea - i'll raise it with Andrew and Phil at our monthly project meeting due this week!

Personally I'm in favour of more tab and slot type detail to avoid the necessity of folding as much as possible



ciao Martyn

Hi Martyn,
To be honest, unless the bend is very tight, I don't think you need to heat it up. Just using a former with it cold is almost certainly going to be ok.

[masahiraoka]

Manifold Isolation Valve Cover

• One item which has proved to be particularly troublesome to 3D model is the cover over the steam manifold isolating valve, see the left-hand side of the photo below of West Country, No. 34053 Sir Keith Park. The fact is that the BR dwg no. W11610 does not show the necessary detail to design this cover in 3D CAD.



• After a great deal of work Phil has achieved the near impossible creating a cover that will in due course be 3D printed.

• The 3D CAD screen shot below shows how closely Phil has been able to model this cover and the associated plumbing compared with that of the full size.



• The following two screen shots show the cover highlighted in orange to show clearly how this piece fits onto the boiler cladding

• The final screen shot shows the isolating valve in place underneath this cover

[masahiraoka]

Missing Full Size Works Drawings

• In our work, through checking cross references between drawings, we've found that there are some full size works drawings that are missing from NRM's collection

• We've been able to source several of these from the Bulleid Pacific Locomotive Assoc. but there are still some missing

• If anyone has any of these drawings, we'd very much appreciate it if you could share them with us.

[Cro]

Hi Martyn,

Went through my collection just now but sadly don't have any of the above drawings.

Adam

[masahiraoka]

thanks Adam
you've already been a big help

best regards Martyn

[masahiraoka]

Update on milling, drill and tapping the stainless steel 3D printed stretchers

• There was some discussion a month ago about the joys of milling, drilling and tapping stainless steel.

• So, I thought I'd update everyone with some comments from Andrew in the workshop

    • On the front stretcher I deliberately put in a new cheap Chinese cutter that is popular amongst hobbyists, 6mm diameter and ran it at 1000rpm giving an approximate cutting speed of 20m/min and ran it dry, it took the 0.010" of each side of the front stretcher and also the 0.005" of each side of the other stretcher but started failing on the last cut on the second stretcher, this was done dry.

    • I would recommend cutting speed at around 15-18m/min with either flood coolant on it or concentrated cutting oil and a max depth with a sharp HSS cutter of around 0.005" depending on the rigidity of the mill as the stretchers are quite thin and prone to chatter.

    • To drill I used a new sharp German Guhring jobber drill at only 10m/min cutting speed and it went through very very easy no chatter or squeal again dry.

    • Tapping I started with a somewhat blunt carbon steel tap but was no good, next tried and average half-used HSS Gun tap, this worked fine.

    • For the second hole I used a brand new normal carbon steel tap like most model engineers use and with plenty of tap magic cutting fluid this went through first time no worries.

    • I suspect a new tap will only last about 6-8 holes before it gets too blunt and starts work hardening the stainless.

    • if someone was using carbide milling cutters they would have no troubles at all in working with it with very little precautions in terms of speeds and feeds so long as chatter was prevented

    • All in all, I think it's a very workable material

• The photos show work on the stretcher between the second and third coupled wheels (ie drawing numbers SR W5472 & BR W11632), and the stretcher in front of the leading coupled wheels (ie SR 5530 & BR W11631).

[92220]

Hi Martyn.

You don't mention it and I can't see it in your photos, but do you use lubricant when tapping the stainless? When I worked with a company that worked almost exclusively in stainless, they always used Rocol RTD compound every time they tapped anything. It helps to prolong tap life. Working there taught me to use Rocol EVERY time I have to tap anything, in ANY metal. Doesn't matter whether it is mild steel, stainless, aluminium, brass or bronze. I have found Rocol works wonders.....and a 250mls bottle last many years.


Bob.

[masahiraoka]

Bob
you're right Andrew did these experiments all dry as he wanted to try the worst possible conditions but he recommends using either a flood coolant or a concentrated coolant such as the one you describe.
regards MArtyn

[masahiraoka]

These shots show the folded tab and slot stretchers described earlier, in place in the chassis
ciao Martyn

[masahiraoka]

Sorry folks it's been three weeks since i last posted - that's a function of having caught up on five years work on the project so posts going forward will be every 10 days or so.

today's news is that we've received a big shipment from the 3D metal printing contractor 

the first photo shows the coupling rods. 



this next photo shows a big collection of parts for the brake gear.



and this one the front bogie stretcher, the outside cylinder exhaust pipes to the smoke box, horns and a platform hanger



and finally this one the trailing truck side frames, the cab stretcher, and the outside ash pan hoppers.



I confess to not having seen these in the flesh yet but Phil assures me that they look excellent - the photos do not do them justice.

i can't wait for these to be sent to Andrew for him to start assembling them onto the chassis.

more detailed close photos will follow shortly

ciao Martyn

[David]

Very interesting project!

I really look forward to 3D metal printing to be affordable.

Having said affordable, I've had loco frames and hornguides waterjet cut in the not too distant past the and it was not cheap, and some little dummy clack valves I'm getting cast in bronze from 3D models are quite expensive too for the size of them I guess due to the complexity of the part.

There's a lot of things in this hobby that aren't cheap and the prices you indicate already put 3D metal printing it near my 'I'd rather pay money than time on it' limit, although I guess 5" gauge parts would be at least 50% more expensive again.

QUESTION: when you say things like 'cutting speed of nM/min, is that the speed the cutting edges are moving, rather than the feed speed? So for a drill or endmill it would be something like the rpm*diameter of cutter? I get very confused by this.

[masahiraoka]

These two photos show the spring hanger brackets fastened to the frame stretchers.

These proved to be quite fiddly to machine, bend and drill to the required dimensions.

So knowing what we know now about the machinability and strength of the stainless steel 3D printed material we took a decision to modify the designs of the frame stretchers for future builds to incorporate the spring hangers as per the full size practice, see the portion of SR drawing E31693 below.

[masahiraoka]

David
in relation to your question about calculating cutting speed the answer is relatively simple and Andrew replies as follows:


"When selecting RPM for a cutter, the thing that counts is how fast the cutting edge moves over the surface of the material so in effect this is the linear velocity at the cutting edge. But to achieve a particular linear velocity at the cutting edge a cutter will need to achieve certain Angular velocity (RPM Revolutions per minute). so there is a simple formula which, if we stick with the metric system is easy to use to find the cutting speed for any diameter cutter or drill or for that matter work piece in the lathe. and that is:

Angular velocity of the cutter or work piece (RPM) = [cutting speed (m/min) x 300] /cutter or work piece diameter in mm

Example:

using a 1/2" (12.7mm) cutter on Stainless steel with a target cutting speed of 12m/min

so: RPM = [15 x300] /12.7

= 4500/12.7

= 354 RPM

This is the approximation I was taught in my first week on lathes at trade school as an 18 y/o lad ( they were good British Edgewick lathes too Ex. Govt defence!)

getting the cutting speed correct on materials is critical to tool life and finish. and at the cutting speed I am suggesting with suitable lubrication from cutting fluid one cutter should do the whole job of the stretchers.

I hope this has mate it just a little clearer."

[92220]

Hi Martyn.

I follow your thread with great interest. It's great to find someone else who is making every detail to works drawings. That simple rpm formula will probably help a lot of model engineers too! I've not heard that one before.

Bob.

[masahiraoka]

thanks Bob

the design process has taken us longer than we thought but the outcome using the CAD/CAM technology has exceeded our expectations. We had worried about 3D printing in stainless steel but we've proved that this is not a problem

ciao Martyn

[cplmickey]

Jul 27, 2020 12:40:58 GMT masahiraoka said:

Example:

using a 1/2" (12.7mm) cutter on Stainless steel with a target cutting speed of 12m/min

so: RPM = [15 x300] /12.7

Presumably if aiming for a cutting speed of 12m/min this should actually read RPM = [12 x 300] / 12.7 giving 4000 / 12.7 or 315rpm

[suctionhose]

While were talking estimating cutter speeds, my method is to compare different sizes and materials to 1" dia Mild Steel.

For a HSS cutter: speed for 1" dia is 300 rpm. double the size - half the speed and visa versa. 1/2" is 600 (lower end of the range but easy numbers to work with)
I then modify the answer according to material: Aluminium x 2 or 3, stainless x .5, CI x .5, EN24 x .66, etc often available speeds fall either side of that number so pick one and see how it goes. For Carbides, the base figure is 2000 rpm / dia in inches.

We learnt to calculate circumference and m/min cutting speed as an apprentice but I quickly saw the above shortcut. That's my system and when you have a casting 8" dia in the chuck I know before the jaws are tightened what speed I'm going to start off at. Of course the feel and sound tells you how to tweak from there (Chatter? decrease speed, increase feed etc)

Feed rate are similar - knowing the sort of finish or rate of removal for a given mm/rev on a lathe or per tooth when milling. Rate should decrease as dia comes down because the helix angle is increasing, increasing the approach angle and reducing the tool clearance....

[masahiraoka]

Here are the most recent screen shots from Phil. It's beginning to look like a complete engine!


Final work required on the engine includes the smaller details such as the buffers, coupling, outside steam pipe covers, hand rails, lubricators, sandbox plumbing, name plate, dummy whistle, boiler clacks & plumbing, other plumbing, cab equipment and details, cab windows, lamp irons, cylinder drain cocks & plumbing, my controversial cab side modification, and no doubt lots of other stuff, there is always more than you think!


Then Phil will split his time supporting Andrew's work on building the loco and designing the tender.