Another Jessie

[uuu]

And here's how far I've got. The blanks have been hacked out of a piece of stainless flat bar (303 grade, hard to find). There was an earlier picture of them in the compltely raw state - what I've now done is mill the ends to 1/4" square and finish the root radius at the shoulder. The longer one is a bit banana, but I can bash it straight.

You may ask why I didn't cut the whole profile in one go, which would resolve the issue I now have with holding the pieces while the hook profile is machined. I need to turn the end of the 1/4" square to round, and thread it. I've not got a four-jaw with a big enough throat to swallow the whole hook and hold onto the square bit. But I can hold the blanks as they now are, with a bit of tailstock support.

So the rounding of the ends and threading is the next job - which I may do at The Pump House, as John's got a gearbox on his lathe - we'll see. Meanwhile I'll make a jig to hold the blanks down for the hook profile.

Then there's a bit of taper mchining to thin down the hook points, and corner rounding.

[uuu]

I managed to get into the workshop for a short session this afternoon. I've turned the square tail on the front hook to round section and have started the thread on it. I'm using a 55-degree turning tool to do most of it, and I'll finish off with a die. Alas I've just chipped the tip on the tool by taking the final cut beyond the previous one.

[jma1009]

hi wilf!

as Mr Grimmett would say, 'hacksaw and file job' re the profiled end! you cant see both ends at once so they dont have to be exactly the same!

very nice work though! i think stainless is a bit too much for drawhooks. they are no less prone to rust than any other unpainted surface - or are you going to do a Jack Austen-Walton and build all the motion out of stainless too? (see Twin-Sisters ME late 1950's)

cheers,
julian

[uuu]

This stainless bar is machining quite nicely. And I have enough for the crank and coupling rods, so I'd like to use it for those.

Wilf

[uuu]

Sept 3, 2013 21:26:09 GMT jma1009 said:

hi wilf!

as Mr Grimmett would say, 'hacksaw and file job' re the profiled end!

Alas that's not the way I work. I say alas, because I often wish I was better at the hand work. It would be quicker than my way, and would almost certainly produce a better result.

I'm producing the profile in the CNC mill. Which would be an appropriate method if I had dozens to do, but is hugely time consuming for just two. There's only one CAD drawing, but it details not only the hook outline and profile, but also the holding jig and clamp. Then there's the CAM process to generate the cutting paths for the tools - there are about twelve cutting routines involved in the job.

With any luck I shall get to cut some metal today, although I may only get the jig and clamp prepared. Even when I get onto the job proper, I'll want to do a test run of each routine on some scrap.

3D printing amuses me. It all sounds so easy - you just feed your drawings into a slot on the front of the machine and a fully formed loco is delivered into the hopper on the back - a bit like photocopying. I look forward to the colour versions, so it's painted already. If the drawing had coal and flames shown, the thing would already be in steam!

[chris vine]

Bad luck on breaking the tip at the end of the thread. I have found that the few minutes it takes to machine a small recess/run-off at the end has saved a few tips!!

The smaller diameter doesn't weaken the component. In fact if it has nice rounded corners, it might make it stronger...

Chris.

[uuu]

Progress, slow as always - but here are the coupling hooks after all the machining.

The picture shows the parent material - the machining jig holding a test piece, and the two hooks.

Wilf

[Shawki Shlemon]

Very nice indeed , you get 10 out of 10 from me .

[ejparrott]

Production!

A friend of mine is building a 9F and machining the majority of components from solid where he can, he'd be interested in seeing that...must remember to show him tomorrow

[vulcanbomber]

Oct 8, 2013 19:18:49 GMT ejparrott said:

Production!

A friend of mine is building a 9F and machining the majority of components from solid where he can, he'd be interested in seeing that...must remember to show him tomorrow

Don't worry, i've already seen it.....

[Roger]

Sept 23, 2013 8:38:50 GMT uuu said:

Progress, slow as always - but here are the coupling hooks after all the machining.

The picture shows the parent material - the machining jig holding a test piece, and the two hooks.

Wilf

I like this very much, and it's possibly the way I'll make the ones for Speedy. I was told by a guy who makes a lot of parts from plate that he never bothers with tooling or 'pips/bridges' but instead clamps down around the job and then leaves the cut about 0.5mm short of cutting right through. The part gets all the support it needs and it takes very little time to cut it from the plate and tidy it up with a file.
I used to have to make some Drawbars from Silver Steel to very high accuracy for High Speed Spindles, and I always used to make the threaded end about three mm longer than the finished length so I could use a tiny half centre to support the thread. It's easy to carefully machine that away once the thread is finished and it supports the end, reducing the chance of disaster and keeping the thread parallel. I've just gone back over your thread and I see that's pretty much what you elected to do too.

[uuu]

What the photo doesn't show is that the jig can also hold the work flipped over, to do the 3D work on the other side. The hook gets thinner in a swoop towards the tip, and the edges are rounded off. Since I've only got 2D software, I had to program all the Z moves by hand.

[Roger]

That's very enterprising, I think I would just have done the 2D machining and finished the third with a file. Still, the pleasure in often in the process so why not go the whole hog. It certainly produced a great result.
I haven't really done much with the 3D machining on mine as yet, it's something I need to play with a bit more. The 3D CAM take a bit of getting used to in order to make it do what you want. I guess that something like the hook would be a good way to properly get under the skin of it.

[uuu]

At last I've had the roof repaired, so it's away with the buckets and waterproof covers over the machines and I can get on with a few bits. Not that progress will be quick!

Here's the buffer beams, now with bits rivetted on, ready to make the square/oblong holes for the coupling hooks.



And here are the brake shaft bearings. I took a leaf out of Roger's book and made these all in one go in the mill. In fact both parts were made back-to-back at the same time.



Wilf

[Deleted]

very nice Wilf... good to see your back in the workshop where we all belong... just don't tell SWMBO..

Pete

[Roger]

Very tidy, it's interesting to see the different ways there are of going about things like that. The key decision on that part is the radius to the flange. I'm curious to know if you used a ball nose cutter for the flat part too, it's hard to see from the photo but the surface seems to have an awful lot of cuts. I generally use as bit a cutter as possible to save time on those areas and only use small ones where there's no alternative. Do you produce the whole program as a 3D machining operation?

[uuu]

Yes, the flange root used a ball-nose cutter. I used a small cutter (not ball nose) for the primary clearance for two reasons: I have small carbide ones, but my larger cutters are HSS, I had cut the parent material slab a bit small, so the clamping wasn't as secure as I'd have liked.

I've not got 3D software, so it's all Solid Edge and CamBam.

Wilf

[Roger]

Apr 5, 2014 7:11:29 GMT uuu said:

Yes, the flange root used a ball-nose cutter. I used a small cutter (not ball nose) for the primary clearance for two reasons: I have small carbide ones, but my larger cutters are HSS, I had cut the parent material slab a bit small, so the clamping wasn't as secure as I'd have liked.

I've not got 3D software, so it's all Solid Edge and CamBam.

Wilf

That makes perfect sense to me. I'd probably have machined the flange in the lathe if I only had small cutters, but at least you could make a cup of tea doing it your way. Do you finish them with a file? I don't like to see machining marks on the model, I prefer to draw file the surfaces. doubtless they wouldn't show when it's painted though.
I've only used 3D software on a couple of occasions, most of the stuff I do can be done in 2-1/2D and I can control the tool paths much better. There's a real art to using 3D CAM in my opinion else you spend half the time cutting fresh air.

[uuu]

I shall file or sand off the marks, although they're not really there at all. The camera seems to have picked them out.

I wondered about doing the flange in the lathe - it was the obvious way. But it was your "component on a stick" approach that led me to experiment with milling them. I'm also fan of helically milling holes.

[Roger]

It's odd how the camera plays tricks like that, I've posted some photos where the opposite is true and I feel like a fake. I think a lot of it is to do with the lighting.
I'm a huge fan of the 'part on a stick' method, I use that more than any other technique because it saves to much time.
I use the pocketing CAM feature that works for holes and any other shape. You automatically get the helical approach and I've not bothered with the dedicated one for holes. My mill uses rotary encoders on the leadscrew at the moment so I wouldn't do anything super accurate that way. I'd drill and ream to make sure they were perfectly round. It's good enough as it is for most things though.
My other favoured method for thin components is to machine only part way through and finish off by hand. That saves an awful lot of time too. If you clamp down to a metal surface you can get within 0.2mm and that's easy to break out the components when they're done.
I'm just about to machine 8 curved dummy balance weights from 1/16" sheet and I'm going to experiment with using my fine pitch magnetic chuck to do the same thing for those on the mill. I've written a little program that lets me step up an array of parts from the CAM output so I'll do a 2x2 array to speed that up. I'll probably use a 6mm cutter and not go too fast just in case it slips. Watch this space.