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| spuddevans:
So I've got the workshop into a place that I can now start to use it for the intended purpose, and I also have got my 1st project done ( A custom titanium ring for my better half. Bribery if ever I saw it :lol: ) so it is on to making another little engine, and wanting to do something different but not too difficult, I settled on Elmers VR75. This is a slide valve engine which I've not tried to build before, and it has reversing gear which also interests me and looks nice too. Before I start I have to apologise to anyone who has a slow interweb connection, as I am firmly a believer in :worthless: and so will be taking loads of pictures of all stages of the process. This may be really boring for some, but I like seeing others machining setups and how they do things, so hopefully someone may find some of my pics interesting :scratch: So after downloading the plans from John-Tom I set about studying them, and like all other of Elmer's plans they are in fractional inches. Many are very comfortable using imperial measurements, but I am not among them. Added to that I haven't built up much of a stash of metal stock, so I decided to make the conversion easy for myself by scaling the plans 16mm to the inch, ie 1/16th" = 1mm. So now that we've got that epic tome out of the way, on to the build log. I started out by making a crude sketch on the whiteboard (one of the most useful purchases in my workshop) of the Engine base with scaled metric dimensions. Then I found a piece of 10mm thick ali plate and stuck it in the bandsaw to trim it to slightly oversize. However I had not checked the bandsaw and it was not cutting straight, fortunately I caught it in time. Then, because one edge was good, I put the good edge to the bottom of the vice on the mill and clamped it up. I also stuck a 16mm endmill in the chuck. As you can see below, when I put an endmill into the chuck I try to always have a bit of wood or a cloth directly below it, you only have to drop it once to increase your collection of blunt endmills :thumbup: You may also notice that I put the Ali over to one side in the vice, the reason for this is illustrated below It saves taking the workpiece out of the vice to measure it. But I think that if the workpiece does not reach past the centre of the vice, then you need to put a packing piece on the other side that is the same thickness to keep the clamping pressure of the vice even. Then after reaching 44mm, I placed the Ali Base on some parallels in order to square the ends and complete the sizing. I've found that when milling edges like this, especially on aluminium, it is helpful (if you have a free hand) to gently hold a paintbrush against the endmill, it helps clear the chips to stop them clogging the cutter. This pic shows what happens when I don't. The brush was held against the endmill for the 1st little bit, then taken away for the rest. Anyway, after measuring and milling, I ended up with this block 64mm x 44mm x 10mm (I don't know whether to thin it down or not :scratch:) So that was as far as I got before the call of the wild (Food), stay tuned for irregular updates :D Next up will be drilling all the corners out and also drilling some holes before milling out the cut-outs. Tim (glad to be back in the saddle workshop again) |
| dsquire:
Tim Good to see you making the chips fly instead of the sawdust. You sound like your having fun. :D :) :D Cheers :beer: Don |
| spuddevans:
Thanks Don :thumbup: I really am having a lot of fun getting used to using my machines again. Ok, so today's seen a bit more progress on the base. I started off by blacking up the base and then marking out the places for all the holes. Not strictly necessary as I was going to machine it using the DRO's, but it I find it to be reassuring to see that the holes are being installed in the right places. Then I mounted the base on parallels in the vice, and then used an edge finder to zero the DRO's in the bottom left corner. Then I can reference all operations from that point. Then I chucked a centre drill in the chuck and then went to each of the co-ordinates and spotted them. Then I did the same thing again with a 2mm drill bit. Then I worked out the corner points of all the cutouts and centre drilled and then drilled through 4mm. Then I started to mill out the cutouts. I started with a 4mm endmill but found it was taking it forever, as I was only able to take 0.8mm depth of cut per pass. After milling out 2 of the cutouts this way, inspiration struck ( or was it a particularly sneaky attack of wind ? :lol: ) and I remembered I have a 1/4" roughing endmill. Sticking that in the mill I was able to hog out 2mm per pass. I was careful to leave about 0.3mm for a cleanup pass with the previous 4mm endmill, and that worked out great and fairly swift too. Having taken the base out to clean it from all the swarf, and having to use some taller parallels in the vice I re-gripped it in the vice to mill out the little steps at each end. This meant having to use the edge-finder on the bottom edge and the left edge to re-zero the DRO's Then it just took a moment to mill the steps. Then I removed the base and set up my little tapping stand, put some tapping lube in each hole to be tapped, and set about tapping M2.5 taper, 2nd, and bottoming taps. So I ended up with this Next up will be bending up some steel for the upright which supports the crosshead guide and cylinder. Somewhere down the line I will be using my faceplate on the lathe for the 1st time ever!! I'm looking forward to that. Thanks for watching, Tim |
| spuddevans:
I've been thinking about bending the Standard up, and came up with one thought. What if I was to mill shallow V grooves in the inside centre of where the bends should be. (shown by the red arrows in the pic below) I figure no more than 1mm deep, max 1.5mm (the steel I have is 1/8"). This should make the bends more likely to be square and at the right place. Also because the bends are close to 90 degrees it should close up the groove mostly and then I can either fill it with JB weld or soft solder. I figure that because I am doing a smaller scale version, but this Standard is being made out of the original thickness steel, I will have enough material to shape/file/mill/grind a better looking radius on each bend if needed. With only machining a V no more than half way through the bends shouldn't be too sharp. What does the collective wisdom think? I'm open for any and all suggestions. If I can get away without working with red hot steel I will, but if it needs heat to bend it so be it, I'm just concerned about getting the bends in the right positions (I don't know if I can heat it that accurately) Tim |
| dsquire:
Tim Why not try milling the V groove in a piece of scrap and bending it. That should give you a pretty good idea of what it would look like and be easier than making the whole part then finding that it doesn't work. That's how I would go about it. :D :D Cheers :beer: Don |
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