Elmers VR75 build log

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Stilldrillin:
That's shaping up nicely Tim! :thumbup:

I like how you formed the standard's corners....... :clap: :clap:

David D

spuddevans:
Thanks Guys :thumbup: :thumbup:

So I got started today on the flange, chucked the bit-o-brass into the lathe and had at it

I turned it to 22mm and bored out where it sits on the crosshead guide. I then set up my little hearth to silver solder it all together.

I used Bog's trick of just cutting a ring of solder and placing it in the flux, then all you have to do is heat it.

It's been a while since I've silver soldered, and I had forgotten just how hot you have to get the parts, but I got there eventually, and once I saw the solder flow I was able to push down on the whole assembly to make sure all the parts were firmly mated before removing the heat.

Then I dumped the whole assembly into a small tupperware container that I use for pickling, filled with citric acid. And there it will stay for a few hours ( probably until tomorrow )

I then thought about the next piece to make, and decided on the cylinder.

I didn't have any brass of the right size ( some much bigger, but it seems a shame to waste so much ) so I found this old Sash weight and thought that would do.

So after waiting for the bandsaw to cut it (and feeling very grateful for having a bandsaw) I faced up one side.

Then turned over and started to face the other, when this happened.

I hit a hard spot, in fact, I hit it going one way, then sharpened the flycutter and hit it again on the way back :doh:

So after thinking a little I remembered Rob Wilson and his carbide flycutter and then noticed that my carbide lathe tools are the same size as the flycutter HSS.

So...

That got it smoothed over. It does a really good job. I just love the silky smooth feeling of fresh flycut metal.

Then as I had a fare bit of material to remove I switched to a 3/8" roughing mill, and was quite surprised to see that my mill was able to take a full width cut 2mm deep

Then once I had it down to dimension, I moved on to the edges.

And then I ran out of time. Next up will be finishing off the other side. Then once all the sides are to dimension I can start turning it into a cylinder. Isn't it funny how often preparing and sizing the stock takes longer than then making the part.

Tim

spuddevans:
So before I got re-started on the cylinder I dug the standard out of the citric pickle, gave it a rub over with an old rag, the joints looked ok, waddya think? I will be facing off the protruding bit at the top.

After hacking off the excess of the cylinder blank, I roughed it to size and finally finished it to size with the flycutter

Then after using the edgefinder to zero the DRO's and then spotted for the top cover

Then drilled it

Then did the same for the the lower end,

Then it was the turn of the valve porting side, spotted

Then drilled,

Before finally joining up the holes in the top and bottom ports with a 2mm endmill.

That sounds all very simple, but it took me all afternoon. I think it was because I was converting from imperial to metric while scaling down and all the while not screwing it up.

Hopefully I have succeeded.

Next will be drilling the angled holes through to each end of the cylinder from the ports. Then it will be over to the lathe to bore out the bore and turn the flange ends.

Thanks for watching.
Tim

spuddevans:
So I started off today by drilling the exhaust hole in the side of the cylinder, it's drilled 2.5mm and will be tapped M3

Then it was time to drill the angled holes to connect the valve to each end of the cylinder. The plans call for them to be drilled at 25 degrees, and not having a tilting vice or a sine-bar setup, I used the next best thing that I did have, a set of angled parallels ( I don't know why they are called parallels as there is only one of each angle )

However the biggest angle is only 10 degrees, so here was my (not-very-pretty) solution, use 3 angled parallels stacked (10, 9 and 6 degrees) (A sine bar setup or tilting vice is definitely on the to-do list)

However crude it looks, it worked. I guess in Elmers engines there is a lot of "wiggle room" on the absolute accuracy of work.

My next great idea was to spot the face with an endmill before drilling, so as to give a level (relative to the drillbit) surface for the bit. However, because of my scaling down the dimensions, I needed to use a 1.5mm or smaller endmill. Not having a 1.5mm endmill I changed chucks and used a 1mm carbide endmill. I know that normally you shouldn't use a drill chuck to grip endmills, but my ER32 chuck wont grip a 1mm shaft.

It all ended up being irrelevent anyway as I was unable to down-feed slowly enough and the endmill just snapped off. So I then did what I should've done 1st, and used a centre drill to spot the face.

and then drilled through with a 1.3mm bit

After repeating on the other end (without the snapping of a 1mm endmill) then it was over to the lathe, and the 4jaw.

Using a wobbler-pin-thingy in the centre drilled centre hole I had drilled in the mill, I centred the bore (or where the bore should be)

I'd been waiting for this for a while and it happened today, things went a little wrong.

If you noted on the above Pic, I used some scrap ali pieces to protect the jaws from marking the cylinder, however I had not paid attention to them and I didn't realise that they were so rough and a little tapered. This had the effect of pulling the cylinder out of square with the jaws.

I didn't realise this until I had drilled the bore 10mm (eventually to be 12mm) and then faced the end off. That's what gave me the clue that something wasn't right, instead of taking 0.1-0.2mm off, I took off nearly 0.5mm.

I should have stopped before taking off so much, but my zeal ate me up.

I then realised that if I was to carry on then everything would be well off, so I took the ali shims off and reclamped without them, and re-centred the drilled bore, re-faced the end, and then set about opening up the bore with a boring bar.

I opened it up to 11.8mm and then used a reamer to bring to final size 12mm.

Hopefully the cylinder is not too short now.

At this point it was feeding time at this zoo so I finished there. Next up will be turning the flanges on both ends, then it will be back onto the mill to shape the outside of the bits between the flanges.

A little off topic, but as I was about to leave the workshop I thought I'd show a little habit I've got into in the workshop

This highly advanced, and may I say, Patent applied for, device is a hanging impliment for my workshop overalls. After reading many horror stories about wearing jewellery around machines I have been determined to form the habit of exchanging my wedding ring for my overalls as soon as I enter the workshop. It's now a habit, a good habit I think.

(thus endith today's lesson)

Tim

spuddevans:
Today I started off by turning the flanges, and it was while I was turning them down to size I found that with my previous mistake with initially gripping and turning off-true has also caused the bore to be off-centre by about 0.3-0.4mm. It's not too bad but it will mean some extra work to try and cover it up as you will see later.

Then it was back onto the mill to mill the little steam/air passage from the previously drilled angle ports so that they meet up with the bore.

Then it was onto shaping the outside of the cylinder, as there was about 3mm depth to come off I used my 3/8" roughing mill to get to within 0.2mm of depth and width,

before switching to a 10mm carbide (no real reason for using carbide, it was just the only 10mm endmill I had, which saved changing the collet in the mill) to bring to final size.

Then, according to the plans (which I am trying to follow as closely as I can, but I think there would be a few things I'd do differently another time, more about that in a bit) I needed to mill 2 45degree sections before (optionally) rounding over. I have already decided not to round it over but to leave it semi-hexi so that solves that, but how was I to hold the cylinder at 45 degrees without a tilting vice or sinebar (or enough room to use many many angled parallels) ??

I had a cunning plan ("was it as cunning as a cunning fox who went to oxford university, majoring in cunning?" "Yes Baldrick") I dug out 2 M2 grub screws and inserted them thus,

Before placing into the vice and holding firmly against the moving jaw until tightened.

This setup is not the most secure, so I took somewhat lighter cuts until I had this,

After doing the other side and then spending a few mins with some 400grit emery to clean up the "whiskers" I had this

That was the angle that makes it look better than it actually is. I said earlier that my mistake led to a slightly off-centre bore, well that meant that the previously drilled and tapped holes on the flanges were also off-centre.

and

So what to do??? They are off by about 0.3-0.5mm. I suppose I could fill with some threaded rod, solder it up and re-face and then re-drill and tap. I could live with it and try and disguise it in the cylinder end caps (I guess only the top will be readily visible)

What I should have done is not drilled or tapped any of the flange mounting holes until after the cylinder was bored out, it would be far easier to find the centre of the bore and then drill the flange mounting holes. But that's what you get for blindly following the instructions poorly.

At least I didn't drill the mounting holes on the top of the standard assembly yet, so I can use some of those M2 grub screws sharpened to a point and inserted into the cylinder to copy the off-centre mounting holes.

Whatever I do it is going to take a bit of thinking and no doubt extra work in machining to get round this.

Thanks for watching,

Tim

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