Postman Cometh Part 2

.

Delivery from the postman again of a set of castings from Stuart for their No.4 engine.

Think I will start from the bottom and work up.

That Jason bloke thinks I should have it finished by this coming weekend including the paint drying.

But first I will have a cup of tea.

Nick

Can't you multi task and drink tea while machining? Just don't pick up the cutting fluid by mistake

That's were CNC comes in for the home shop, drink tea while creating the program on your computer and then have another cuppa while watching the CNC bugger up your castings.

Order replacement castings then repeat. (well that's what I did anyway!)

Steve

Wow looks good Nick, look forward to following along...

Garry

that there flywheel casting looks a bit ropey !

Funny you should say that, it does look like most parts have been shell cast and have a very smooth finish, cylinder looks to be sand cast and maybe balast for the flywheel?

.

You are right. In the photographs it does look so.

I will go and have a nosey at it and let you know.

Oh and that cup of tea also turned into a 2 hour snooze, which means I will not sleep tonight now.!

Nick

A moment of empathy for the postman might be appropriate

Is that flywheel oval shaped?

Edited By Ady1 on 19/08/2015 20:17:09

.

Had a look at the flywheel.

It's OK Just thin flashing and the halfs are aligned reasonably well.

Phew.! Nick

.

Well actually it was a courier. But me being an old fashioned sort of guy I remember when the postman delivered everything. Even remember as a kid that it was not unknown for a postman to deliver on Christmas day.!

Oval flywheel.? ............. Bugger off you.!!! (but I suppose it will be to some degree)

Nick

.

So we make a start.

The boxbed had it's worst high spots filed off and was milled with a fly cutter on both sides.

Similar was done with the sole plate on the bottom. However I would have had to make special mounting brackets / plates to do the top surface due to its shape and small size. I could have made several passes on it with moving the mountings but I ideally wanted to make the cuts on it in a single pass.

So it was mounted for the top face cuts in the 4 jaw on the lathe. I had to be careful to tighten it enough so that it would not move under cutting yet not so tight that it introduced a twist in it or even fractured it. However it seemed to go all OK producing a nice flat and good finish.

Nick

Hi Nick

Great to see you've made a start, I'm quite envious of that nice Lathe you have..! Also interested to see what to me anyway looks like a 'button' profiling tool in the milling cutter - I've not seen anything like that before. Looks like it does a nice job..

and look forward to seeing the next update..

Cheers

Garry

Edited By Garry_C on 21/08/2015 12:22:18

.

I found a lazer edge finder very useful for getting some 'sort of' ref points on the sole plate I say 'some sort' because although Stewart have revised the drawing for this part concerning the bearings the 4 studs and nuts that hold it to the boxbed would also not work.

.

Next was the standard. I made a mandrill to make a press fit to the bore of the casting and drilled and tapped M6 threads in it.

.

This was so that I could machine the feet of the standard 'reasonably' true to the bore.

This went all OK with a newly sharpend bit in the tool holder considering the unsupported legs of the standard and I was happy with the finish. I did however change the live centre from the one in the image to a more heavy duty one as I did not want to knock the backside out of my best one on the interrupted cuts.

Again it became apparent that the casting was slightly undersize length in order to clean the faces up. This is an important length.! I will be able to recover this though by making the cylinder bottom slightly thicker to compensate.

Small video here :- **LINK** It sounds like a steam engine already making the interrupted cuts.

.

The standard was reversed and mounted onto the face plate. I was sure this setup would need beefing up for facing and boring.

Since the above image was taken I made a few tentative cuts into the bore with a 16mm solid carbide boring bar that I snaffled on ebay for a sinch. (nobody else bid.) I really am impressed with it. The bore cleaned up after 20 thou. So it seems the mandrill did its job of finding the average of the rough cast bore.

Made a few passes after the bore cleaned up and measured each of the bore ends with a telescopic gauge. To my surprise there was only 1/2 thou difference over the 2 3/4 inch length with a really nice finish. I will bore the rest out today to 1 1/8th and see if I can cock it up.

Another short video clip here :- **LINK**

When I come to make the cross head how much undersize do you think I should aim for relative to the 1 1/8th of the standards bore.?

More later I hope.

Nick

Its not a size I would measure, just feel the fit of the two parts, probably less than a thou if measured. Worth lapping the trunk guide before you make the crosshead.

.

.

Decided to make the cross head tonight.

I used some EN8 bar I had against the piece supplied as it would have been more fiddly to work with the shorter piece.

Drilled and tapped the hole to take the piston rod.

Over to the mill to carve out the shape. I had to do this in a few passes as the correct size one was not sharp.! (I need to spend some coins on some decent ones)

And here we are. ....... Although I do need to drill and ream the 1/4" hole across it to take the conrod gudgeon pin. I may make this a little larger than 1/4" and bush it. Then make the hole in that 1/4"

That's it for tonight. Been a long day with an early start. If I continue I am likely to make a dogs-danglers of it.

Nick

.

Decided to progress with the bearings and the work on the solepate to accept them.

I machined them in the pair so as to keep them as close as possible to each other. The downside to this is that if I dropped a clanger I would have to buy 2 castings not one.

They came out OK as near as dammit identical.

I attacked the soleplate to accept them.

Nice snug fit.

Next I have to mill across the soleplate the correct width and depth so they drop in. (hopefully nice and snug.)

Doing this stage has taken me far, far longer than I thought it would.! But I have had a nice relaxing day machining, brew drinking, bacon buttie chomping and throwing in the occasional 'move' to Smooth FM. Mate also came round on his mint Norton Commando wanting to know could he use my machines soon to make parts for a turbo 1100 Kawasaki he is building.

Nick

.

Pressing on I cross milled the soleplate and fitted the lower bearing halves.

So onto the bearing caps.

After milling the bottoms and dressing on some abrasive I heated them and then tinned them with electronic cored solder.

Back to the blow torch and the were joined together.

Over to the lathe and into a 4 jaw chuck. I used a dial indicator and a laser finder in the tailstock to make the best 'guesstimate' of certre-ish alignment.

It produced this :-

Which I was then able to mount into a collet chuck to do the opposite side and bringing it to size.

Time for the blow torch again to separate them.

Dressed the bottoms to remove the solder film that had been left and had the following.

Nick

.

Question.

I intend to mount the soleplate with it's bearings in situ facing upwards to drill them out close to size on the mill with the last pass being a reamer. (yes I know line boring would be better. But I don't have T slots on my lathe cross slide.)

I will gradually make the holes larger with progressive drills (new nice sharp ones) before stopping slightly short of target for the reamer.

My question is when drilling into the gunmetal bearings that is known for 'snatching' what sort of step between drill sizes should I go for.? Also what sort of speeds for these drills.? I am presuming a slow feed will also help avoid any snatching.

Cheers, Nick

I would probably go 1/4", 3/8" then reaming size slowing the speed down quite a bit after the first drill and as slow as you can get it for the reamer. Make sure you get a good accurate start into the second bearing, a long series 1/4" centre drill is handy for this sort of thing as it can be guided by the 1/4" pilot hole in teh first bearing.

Yes using the mills downfeed will help a lot to stop snatching