Postman Cometh Part 2

Hi Nick

I found that a lot of heat is generated very quickly with gunmetal and it helped to try and keep things as cool as possible as the snatching seemed to 'especially want' to happen when hot, I took my time and let things cool between each drill bit - still managed to burn my finger last time though as I remember. It was something Jason said to watch out for at the time - as usual it was very good advice..

Hope it goes well..

Cheers

Garry

Edited By Garry_C on 01/09/2015 17:18:44

Having negligble experience of these steamy devices ... A question if I may:

Would it be wise [and/or common practice] to insert a thin shim between the halves before boring?

MichaelG. [happy to be ridiculed or educated]

I've never shimmed model bearings, Its done quite often on the full size hit & miss engines though with either bronze or white metal bearings. My thoughts are that we are not going to be running them lots and if they should wear then the mating "flat" areas are small enough to be rubbed on a sheet of Emery to remove a little metal if you needed to close up the hole.

I usually solder mine together before boring so you will get a slight gap once they are melted apart and the solder cleaned off.

As Nick's No 4 does not use a separate top half of the bearing and bearing cap the only way to close up any gap would be to pack up the lower bearing. I prefer to have separate caps that are clear of the bearing housing when the bearing is in place so they can close up any gap in the bearing in future.

J

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Cheers for the replies guy's

Michael. - I understand your logic regarding the shims and I it's a fair point.

Jason and Garry. - Thanks for the information.

My plan is (please tell me if its a good one or not) is to mount the soleplate with just the bearing bottoms fitted. Then with a piece of precision ground 12mm stock in the collet holder adjust the mill bed until I can just feel contact on both bearing bottoms with a feeler guage.

Remove the 12mm stock and using the DRO I have fitted to the mill subtract the width of the feeler guage. Then subtract an additional 6mm to hopefully bring the center of the mill over the line of the bearing split. Pop on the caps and then sally forth.

Good plan or a disaster in the making.?

Cheers again, Nick

Sounds like you need to get yourself an edge finder or a centre finder/sticky pin to pick up the joint

J

PS have you sorted out your DRO problem yet?

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My thoughts are that if I use the 12mm PGB that I could also check the vertical alignment of both bearings is good. I don't think my edge finders are long enough to do that with the lower mounted one. Suppose I could use the laser one.

Yes, DRO problem sorted. That was down to the idiot that installed it not doing a finished job. - Now I wonder who that was. i.e. the sensor to magnetic scale was not tightened. Ooooops.!

Nick

Edited By Nick_G on 01/09/2015 19:34:24

If you don't have a decent angle plate to mount the casting to then thats probably your best bet of getting the two bearings vertical.

J

Nice work Nick, I'll look forward to following this thread

Peter.

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Thank you Peter.

Work on the bearings has had to take a break for a couple of days. This is due to me being a numptie and not being in possession of a 4BA tap to hold the caps down. So I hope Messers Chronos dispatch the ordered one pronto.

Nick

M3.5 / M4 would've been the nearest equivalent taps if you were stuck... ?

George.

Probably best to stick with 4BA then you can use the supplied nuts & studs, Nice chart, where have I seen that before

Hmmm let me think ... ... gadzooks sir twer it not yours...

.

Cheers mechman,

But as Jason says I have the studs and I have ordered the HSS taps now.

I also really need to replace the existing BA taps I have with HSS ones also. I was very lucky I did not snap the cheep carbon steel ones I bought when building the James Coombes off in castings a couple of times.

Nick

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I have been waiting for some tools to be delivered. (still not arrived today )

So I spent a bit of time over the weekend making a few tools that I will need. I need at some point to drill and face off the standard. This is quite close to other parts of the casting so I would not be able to do it with standard bits of kit. I therefore turned some scrap drilled and reamed the ends to accept such. These were locktited in as they will not be required to be a long lasting service item.

The milling bit and drill were held in the tailstock to ensure they went in reasonably straight.

This is what they are needed for. :-

Also made some T nuts to take some M8 fixings that will be required later. (the ones I already have take M10)

The fly wheel is 5in dia (or hopefully will be ) In order to mount it on the faceplate I would have to drill extra tapped holes into the hub of the D1-3 section. It's not the best of quality faceplates anyway and I am aware that before too long and many projects it would end up looking like the backstop wall after a Mafia firing squad had been active. So on the recommendation of another member I purchased a 20mm thick piece of aluminium. This I will drill and tap onto the plate. (and hopefully stiffen it up a bit) I can then drill and tap fixing holes when ever and where ever I want in the best position for many years to come. Well I hope for many years anyway the price of the damn stuff.

Nick

You may find that milling cutter gets a bit lively when you try to use it that far out of the chuck, what you really need to make is a reverse spot facer, easily filed up from a bit of Silver steel, hardened and then clamped onto your drill bit.

Can you not use the 4-jaw to hold the flywheel by the inside of the rim? You can usually fit a six spoke in OK

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Hi Jason,

That is an inovative way of doing it by reversing the casting. I would never have thought of that. I have though done it before I posted that image and your response.

I was mindful of possible chatter but I just had to spot face not cut into a fillet of the casting as you have done. It went OK, but if I had material at an angle to remove I would I think have had problems. Your method is going into filing cabinet in my bonce for future use though.

I did consider the 4 jaw for the fly wheel as you suggest, but I think I will be more confident with the faceplate method.

Thanks, Nick

Same cutter can be used the right way round fixed to an extended drill or bit of rod so you have a spigot that locates in the hole much like an off the shelf counterbore.

I'd also slip a bit of MDF or ply between your ali plate and the flywheel, that way you can machine right across the rim without scoring that nice shiny new plate

Edited By JasonB on 08/09/2015 07:47:41

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Hello again folks.

It's been a while since I did any work on the No.4. Hopefully I can now get back into the swing of it after my little interlude of making some parts for my mates motorbike turbo conversion. Work has also got in the way of things amongst other distractions.

I don't know how others drop straight back into a project. But I find it takes me a few sessions to remember where I was and my plan of attack.

Anyway. Decided to finish the main bearings. So they were mounted onto the milling table and drilled out in stages.

I did ream to final size but forgot to photograph.

Then onto machining the flywheel. I decided to use the faceplate method.

I drilled and tapped some holes to fix the flywheel and mounted it with some ali spacers behind.

There was an inconsiderate blow hole that reared it's ugly head while facing one of the sides. So I had to machine a bit more off than I would have liked. There is still a little bit visible though Grrrrrrr.! But I suppose I can live with that.

Resharpened the tool for the final cuts and while it was in the lathe gave it a polish that if had been witnesses by the safety Nazi's would have caused outrage.

Flipped it over and skimmed and polished the other side face.

In the morning I will decide what part I shall puzzle with next.

Cheerio, Nick

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Con rod time I think.

I have made a sort of split collet out of aluminium so that I can 'hopefully' hold the rod for the rest of the machining jobs. Any other ways of doing such would of course be welcome.

Nick

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The bearing was sliced with a slitting saw and then faced each side.

It was then fastened back together with solder and machined into thus :-

Another blast of heat to separate the halves again.

Which just leaves a tad of final dressing and a polish.

Nick